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HomeMy WebLinkAboutMisc 1 of 2Vantage Point Apartments Technical Information Report February 7, 2014 Consulting Engineers FEB 2 I 20:: CIT ,, . '• i :.··-., I"',,,',., ... i!'I PLA.1\J;\J/:·~c U!Vi:..:!ON Technical Information Report January 27, 2014 Prepared for: Tonkin Architecture 204 First Avenue South Seattle, WA 98104 Prepared by: KPFF Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, WA 98101 (206) 622-5822 Vantage Point Apartments Technical Information Report i Table of Contents 1. 2. 3. 4. 5. 6. 7. Vantage Point Apartments Technical Information Report Project Overview ............................................................................................................. 1 Condition and Requirements Summary ............................................................................ 1 Core Requirement No. 1: Discharge at the Natural Location ........................... 1 Core Requirement No. 2: Off-Site Analysis...................................... 2 Core Requirement No. 3: Flow Control ...................................................................................... 2 Core Requirement No. 4: Conveyance System ........................................................................... 2 Core Requirement No. 5: Erosion and Sediment Control ................................................ 2 Core requirement No. 6: Maintenance and Operations ........................................... 2 Core Requirement No. 7: Water Quality...................................................... . .................. 2 Off-Site Analysis ............................................................................................................. 2 Task 1: Study Area Definition and Maps .................................................................................... 2 Task 2: Resource Review .. . ...................................................... 3 task 3: Field Inspection ....................................................... 3 Task 4: Drainage System Description and Problem Description .............................................. 3 Task 5: Mitigation of Existing or Potential Problems ................................................................. 3 Flow Control and Water Quality Facility and Design .......................................................... 4 Existing Site Hydrology (Part A)..................................... .. ........................................ 4 Developed Site Hydrology-Flow Control (Part B) .................. .. .................................. 4 Developed Site Hydrology-Water Quality ................................................................................ 5 Performance Standards (Part C) ................................................................................................. s Conveyance System Analysis and Design .......................................................................... 5 Special Reports and Studies ............................................................................................. 6 Other Permits ................................................................................................................. 6 ii .k ff 8. Construction Stormwater Pollution Prevention Plan Analysis and Design ............................. 6 Erosion Sediment Control Plan Analysis and Design (Part A) ..................................................... 6 Stormwater Pollution Prevention and Spill Plan ......................................................................... 6 9. Bond Quantities, Facility Summaries, and Declarations of Covenant .................................... 7 Bond Quantities Worksheet ...................................................................................................... 7 Flow Control and Water Quality Facility Summary Sheet and Sketch ......................................... 7 Declaration of Covenant for Privately Maintained Flow Control and Water Quality Facilities ...... 7 10 • Operations and Maintenance Manual ............................................................................... 7 Appendices Appendix A-Maps and Worksheets • TIR worksheet • Site Location Map • Existing Conditions Map • Drainage Basin Map • Soil Map • Offsite Analysis Map, Table, and confirmation record • Upstream Analysis Appendix B -Drainage Facility Documentation and Design • Detention Pond Documentation and Design • Rain Garden Documentation and Design • Backwater and Conveyance Analysis Appendix (-Special Reports and Studies • Flood Zone Map • Geotechnical Recommendations Appendix D-Construction Stormwater Pollution Prevention Plan • SWPPP Report and Calculations Appendix E -City of Renton Documents Vantage Point Apartments Technical Information Report iii k ff • Bond Quantity Worksheet • Declarations of Covenant Appendix F -Operations and Maintenance Manual Vantage Point Apartments Technical Information Report iv k ff Vantage Point Apartments Technical Information Report y 1. Project Overview The project site is located at 17901105th Place Southeast, Renton, Washington 98055. The existing site topography is the result of historical legal mining operations as noted in the Geotechnical Report in Appendix C. The site is a relatively level grass covered bench, projecting approximately 200 feet southward and westward from Southeast 108th Street and 105th Place Southeast, respectively. Grades on the bench vary from 5 percent to 25 percent sloping toward the roadway. Outward of the bench is a steep slope at upwards of 50 percent down to the Vantage Glen Mobile Park on Southeast 181st Street. The project proposes to shave down the bench, extending the top of steep slope to the west and south. The project does not propose clearing on the steep slope to remain. Stormwater sheets off of the existing site toward the City of Renton (City)-owned collection system in Southeast 108th Street and 105th Place Southeast. Runoff generated from the steep slope flows to the collection system at the toe of slope. The site area of disturbance is 4.01 acres. The proposed development includes an apartment building with two four story wings connected by a central common space. The north wing has one level of underground parking and the partially underground first floor of the south wing is mostly parking. There are two surface parking lots, one associated with the north building and the other with the south. Stormwater runoff from the proposed development will be collected in a series of catch basins and swales. Target pollution generating surfaces will be treated by on-site rain gardens to receive Enhanced Basic Water Quality Treatment. The treated runoff is then routed to a Level Two detention pond to protect downstream fish bearing streams. The detention pond outlets to the City-owned storm drain in 105th Place Southeast. There is no change to the existing site discharge point. All runoff from property within City right-of-way (ROW) that is within the limit of disturbance is considered bypass flow. The detention facility is designed with a downstream point of compliance that accounts for this bypass flow. 2. Condition and Requirements Summary The project is subject to all requirements in the City amendments to the 2009 King County Surface Water Design Manual. The Core Requirements are listed below. No special requirements are applicable to the site. CORE REQUIREMENT NO. 1: DISCHARGE AT THE NATURAL LOCATION The project discharges to the two natural locations, the City-owned collection system in Southeast 108th Street and 105th Place Southeast, and the collection system at the toe of the steep slope in the Vantage Glen Mobile Park area. Vantage Point Apartments Technical Information Report 1 k ff CORE REQUIREMENT NO. 2: OFF-SITE ANALYSIS An off-site analysis was performed on December 91 2013. See Section 3 for details. CORE REQUIREMENT NO. 3: FLOW CONTROL The onsite Level 2 detention pond provides flow control to meet the Flow Control Duration Standard (Forested Conditions). The offsite basin does not exceed the threshold for detention, none is provided. See Section 4 for details. CORE REQUIREMENT NO. 4: CONVEYANCE SYSTEM All pipes and swales convey the 25-year event with 6 inches of available freeboard, with the exception of the trench drains. The shallow nature of these systems does not allow for the 6" free board. The pipes and swales convey the 100-year event without overtopping. See Section 5 for details. CORE REQUIREMENT NO. 5: EROSION AND SEDIMENT CONTROL The project will comply with the National Pollution Discharge Elimination System (NPDES) permit. See Section 8 for details. CORE REQUIREMENT NO. 6: MAINTENANCE AND OPERATIONS The project will maintain the stormwater facilities. See Section 10 for details. CORE REQUIREMENT NO. 7: WATER QUALITY The project will provide enhanced basic water quality for all target pollution generating surfaces. See Section 4 for details. 3. Off-Site Analysis A Level 1 off-site analysis was performed on December 9, 2013. City GIS data was used to assess the drainage network in the area and determine the flow path downstream. TASK 1: STUDY AREA DEFINITION AND MAPS The study area for the site extends 1 mile downstream of the project. Discharge from the site enters the City conveyance system in 105th Place Southeast and Southeast 18o'h Street and flows north to the 60- inch crossing at 105th Place Southeast and Southeast Carr Road. Runoff then enters a tributary of Panther Creek. Runoff is carried in Panther Creek the remainder of the mile. There is one piped road crossing at Al bot Road South, 3/4 mile downstream of the site. See Appendix A for off-site analysis figure. Vantage Point Apartments Technical Information Report 2 k ff TASK 2: RESOURCE REVIEW Available flood plain maps 1 soil surveys, and sensitive area maps were reviewed to assess potential flooding or erosion associated with the development. City engineering staff was contacted for any known flooding problems in the area as well. The information available shows that there is no drainage problem that would be aggravated by the development. The proposed detention pond will reduce flows entering the City system compared to the currently grassed field. See Appendix A for correspondence with City staff and soils map, and Appendix C for Flood Insurance Rate Map. TASK 3: FIELD INSPECTION The field inspection was performed December 9, 2013. The weather was sunny and approximately 30 degrees Fahrenheit. There had been no rain for the past week. The field inspection started at the proposed connection to the system in 105th Place Southeast. Surface conditions at structures did not indicate any overtopping or street flooding. The City system outfalls to a Panther Creek tributary just at the end of the 1/4 mile. The outfall is a 60-inch corrugate metal pipe (CMP). The creek bed is made up of large cobbles that appear to be stable. The side walls ofthe creek and surrounding trees show no evidence of landslides or instability. Scouring was not observed at the outfall or immediately downstream. TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTION The drainage system downstream of the site consists of (MP pipe ranging from 12 inches to 60 inches. There were no signs of flooding or erosion along the system within 1/4 mile of the site. See Appendix A for Off-Site Analysis Figure and Off-Site Analysis Drainage System Table. TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS The drainage system shows no sign of flooding or erosion downstream of the site; no additional mitigation is proposed. Vantage Point Apartments Technical Information Report 3 .k ff 4. Flow Control and Water Quality Facility and Design EXISTING SITE HYDROLOGY (PART A) The existing site has no defined storm water conveyance features or constructed improvements. The site slopes from 5 percent to 25 percent toward Southeast 108th Street and 10sth Place Southeast and upwards of 50 percent to the south and west. The ridgeline ofthe steep slope splits the site into two Target Discharge Areas (TDAs). Runoff from the onsite area is collected in the roadway gutter and piped north and west to a Panther Creek tributary. Runoff from the offsite area sheet flows down the steep slope and is collected in a series of catch basins at the toe. These outlet to a different leg of Panther Creek. The two basins join in Panther Creek greater than one quarter mile downstream. Soils on the site are classified asAlderwood gravelly sandy loam by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). Borings on site show glacially consolidated soil beneath unengineered fill. King County RunoffTime Series (KCRTS) till soil classification is appropriate for this site. The site is located in an area defined by the City as "Flow Control Duration Standard (Forested Conditions)." The pre-developed condition is modeled as Till Forest using the existing onsite basin area accordingly. See Appendix A for Existing Condition Map. DEVELOPED SITE HYDROLOGY -FLOW CONTROL (PART B) The developed site will be a combination of hardscape, landscape, and flow control Best Management Practices (BMPs). Grasscrete, permeable paving, and a detention pond all serve to control runoff from the site. The alternative paving systems allow for the respective areas to be modeled as either a combination of grass and impervious or completely grass according to Table 1.2.3.C in the City amendments to the 2009 King County Surface Water Design Manual. The detention pond is designed using KCRTS to meet the Flow Control Duration Standard (Forested Conditions) of the existing onsite basin. The pond is unlined and is allowed to infiltrate into the native soils. The design infiltration rate for the detention pond is 0.40 inches per hour (150 minutes per inch). See the geotechnical report in Appendix C forsupporting test data. All proposed cover types are modeled as impervious or grass till soil. The offsite basin does not meet the area thresholds for detention. The proposed site geometry prohibits leaving the existing basin divide line intact. The proposed grading diverts all runoff south and west of the outer access road to the offsite basin in order to preserve the existing area as much as possible without causing erosion from concentrated piped flows or excessive impervious area. The proposed basin divide line diverts only 0.12 Acres to the Onsite Basin. This diversion is compensated for by using the existing onsite area in the pre-developed condition. See Appendix A for Basin Map and Soils Map, and Appendix B for KCRTS program input and output files. Vantage Point Apartments Technical Information Report 4 k ff Table 1-Area and Peak Flow Summary Pre-Developed Developed On-Site - Area 3,20 Acres 3.32 Acres 2-Year Peak Flow o.089CFS 0.075 CFS* ---- 10-Year Peak Flow 0.155 CFS i 0.147 CFS* 25-Year Peak Flow 0.202 CFS o.161CFS* Off-Site Area o.81Acres o.69Acres *Release rate at the downstream Point of Compliance DEVELOPED SITE HYDROLOGY -WATER QUALITY The site is considered a multifamily development. According to Section 1.2.8.1.A, enhanced basic water quality treatment is required. Pollution generating site areas are piped to two rain gardens. The rain gardens are designed according to Appendix C.2.5 of the 2009 King County Surface Water Design Manual and City amendments with 18 inches of bioretention soil and an underdrain to filter at least 91 percent of the runoff volume through the underdrain. Infiltration is not used in the raingarden design because underdrains are used. See Appendix B for supporting documentation. PERFORMANCE STANDARDS (PART C) The site falls within the Flow Control Duration Standard (Forested Conditions) as depicted on the Flow Control Application Map in the City Amendments to the 2009 King County Surface Water Design Manual. 5. Conveyance System Analysis and Design The conveyance system consists of swales, pipes, and catch basins. All pipes and swales are sized to convey the 25-year event with 6 inches of freeboard and the 100-year event without overtopping. Due to the shallow nature of the trench drains the 6 inches of free board is not attainable along the entire grate. The trenches have a 0.5 percent sloped bottom that can convey the 25 year event at the shallowest trench section with the largest contributing area (Trench Drain -107). See Appendix B for Trench Drain - 107 calculations. The longest and flattest trunk line, Trunk 100, has been analyzed for backwater effects. The system in 105th Place SE is modified to accept the invert of the pipe from the detention pond. Vantage Point Apartments Technical Information Report 5 k ff Upstream ofthe connection the pipe has been steepened and downstream it has been flattened to 1.0 percent. Backwater calculations have been provided upstream of the connection point to ensure the new pipe profile meets the conveyance standards. All other pipes have been sized using Manning's equation and engineering judgment considering contributing area and pipe slope. Backwater calculations are based on the 2009 KCSWDM. See Appendix B for conveyance calculations. 6. Special Reports and Studies See Appendix C for Flood Zone Map and Geotechnical Recommendations. 7. Other Permits The project will require an NPDES Stormwater Permit. 8. Construction Stormwater Pollution Prevention Plan Analysis and Design EROSION SEDIMENT CONTROL PLAN ANALYSIS AND DESIGN (PART A) The only stormwater pollutant anticipated during construction is silt laden runoff. Treatment BMPs should ensure silt laden runoff does not enter the City conveyance systems or natural channels. Check dams, catch basin inserts, and one large sediment pond will provide treatment prior to discharge. Stabilized construction entrances and sweeping should keep the City streets free from debris. See Appendix D for sediment pond sizing calculations. The sediment pond will be located within the footprint of the proposed detention pond. The sediment pond bottom will be set above the proposed detention pond bottom to ensure the native infiltration rates are restored to the pond prior to final grading. The required surface area for the Sediment Pond is 1,973 square feet. At a three to one length to width ratio, three to one side slopes, and a 3.50 foot depth, this area corresponds to a volume of 3,523 cubic feet. See Appendix D for BMP layouts, details, and calculations. STORMWATER POLLUTION PREVENTION AND SPILL PLAN The contractor may elect to install other BMPs to suit the current site condition as opposed to BMPs shown on the construction plans. These options are outlined in the Stormwater Pollution Prevention Plan report. The contractor will update the plan and report as site conditions change and add spill prevention Vantage Point Apartments Technical Information Report 6 BMPs when specific pollutants are stored or used onsite. See Appendix D for Stormwater Pollution Prevention Plan. 9. Bond Quantities, Facility Summaries, and Declarations of Covenant BOND QUANTITIES WORKSHEET See Appendix E for bond quantity worksheet. FLOW CONTROL AND WATER QUALITY FACILITY SUMMARY SHEET AND SKETCH See Appendix B for summary sheets and sketches of the rain gardens and detention pond. DECLARATION OF COVENANT FOR PRIVATELY MAINTAINED FLOW CONTROL AND WATER QUALITY FACILITIES See Appendix E for Declaration of Covenant for Inspection and Maintenance of Stormwater Facilities. See Appendix E for Declaration of Covenant for Maintenance and Inspection of Flow Control BMPs for the detention pond. 10. Operations and Maintenance Manual See Appendix F for Operations and Maintenance Manual. Vantage Point Apartments Technical Information Report 7 Appendix A Maps and Worksheets Vantage Point Apartments Technical Information Report Appendix A KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT {TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner King County Housing Auth. Phone (206)574-1237 Address 600 Andover Park West. Tukwila, WA Project Engineer Christopher Borzio, PE Company KPFF Consulting Engineers Phone (206) 622-5822 Part 3 TYPE OF PERMIT APPLICATION D Landuse Services Subdivison / Short Subd. / UPD ll!J Building Services M/F / Commerical / SFR IXl Clearing and Grading IX) Right-of-Way Use D Other Part5 PLAN AND REPORT INFORMATION Technical Information Report Type of Drainage Review ~ I Targeted (circle): rge Site Date (include revision dates): Date of Final: Part 6 ADJUSTMENT APPROVALS I Part 2 PROJECT LOCATION AND DESCRIPTION Project Name Vantage Point Apartments DDES Permit# ---------- Location Township ~T-23=N~---- Range ~R=5E~----- Section 5..,3,,_,2=------ Site Address 17901105th Place SE Renton, Washington 98055 Part 4 OTHER REVIEWS AND PERMITS D DFWHPA 0 COE404 D DOE Dam Safety D FEMA Floodplain D COE Wetlands D Other __ _ D Shoreline Management ll!J Structural RockeryNault/ __ D ESA Section 7 Site Improvement Plan (Engr. Plans) Type ( circle one): ~ I Modified / all Site Date (include revision dates): Date of Final: Type (circle one): Standard / Complex / Preapplication / Experimental/ Blanket Description: (include conditions in TIR Section 2) Date of Annroval: 2009 Surface Water Design Manual 1/9/2009 1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yest[§] Describe: Start Date: Completion Date: Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: _T_a_lb_o_t __________ _ Special District Ove~ays: ----------------------- Drainage Basin: Panther Creek Stonnwater Requ"""'i-re_m_e-nt,...s-: """F,,...lw----,,C.,..tr-,-1 "'D-u r"""'S""t-,d""'(""Fo-r-e"""'st,...e"""'d""'C~o nd itions ), Enhanced Ba sic WQ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS D River/Stream --------- 0 Lake !XI Wetlands __________ _ D Closed Depression _______ _ D Floodplain _________ _ D Other ___________ _ Part 10 SOILS ~ Steep Slope --------- 0 Erosion Hazard -------- 0 Landslide Hazard------- 0 Coal Mine Hazard------- 0 Seismic Hazard -------- 0 Habitat Protection------- 0 __________ _ Soil Type Slopes Erosion Potential AgC +-50% max High on stee(,! slo(,!es D High Groundwater Table (within 5 feet) 0 Sole Source Aquifer D Other D Seeps/Springs D Additional Sheets Attached 2009 Surface Water Design Manual 2 1/9/2009 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION/ SITE CONSTRAINT D Core 2 -Offsite Anal:tsis D Sensitive/Critical Areas D SEPA D Other !!I MAINTAIN NATURAL DISCHARGE SITE HAS TWO EXISTING TDAs D Additional Sheets Attached Part 12 TIR SUMMARY SHEET lnrovide one TIR Summa~· Sheet oerThreshold Dlscha= Areal Threshold Discharge Area: Developed Site (name or description) Core Requirements (all 8 apply) Dischame at Natural Location Number of Natural Discharoe Locations: 1 Offsite Analysis Level: [I]/2/3 dated: Flow Control Level: 1 ill.]/ 3 or Exemption Number (incl. facility summarv sheet\ Small Site BMPs Conveyance System Spill containment located at: Erosion and Sediment Control ESC Site Supervisor: Contact Phone: TBD After Hours Phone: Maintenance and Operation Responsibility: 1 Private I/ Public If Private, Maintenance Loa Reauired: Yes / No Financial Guarantees and Provided: i.Y§ I No Liability Water Quality Type: Basic / Sens. Lake / !Enhanced Basir.ml / Bog (include facility summary sheet) or Exemption No. Landsca= Manaaement Plan: Yes / No Soecial Reauirements las annlicablel Area Specific Drainage Type: CDA / SDO / MDP /BP/ LMP / Shared Fae. n None I Reauirements Name: Floodplain/Floodway Delineation Type: Major / Minor / Exemption / !None I Flood zone X 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: Source Control Describe landuse: (comm./industrial landuse) Describe any structural controls: 2009 Surface Water Design Manual 1/9/2009 3 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Oil Control High-use Site: Yes / lt!!lll Treatment BMP: Maintenance Agreement: Yes / No with whom? Other Drainaae Structures Describe: Detention pond, Raingarden, Swales, Catchbasins, and Drainage pipes. Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION IXI Clearing Limits lKI Stabilize Exposed Surfaces IXI Cover Measures IXI Remove and Restore Temporary ESC Facilities IXI Perimeter Protection IXI Clean and Remove All Silt and Debris, Ensure lXJ Traffic Area Stabilization Operation of Permanent Facilities IXI Sediment Retention 0 Flag Limits of SAO and open space IXI Surface Water Collection preservation areas 0 Other D Dewatering Control IXI Dust Control 0 Flow Control Part 14 STORMWATER FACILITY DESCRIPTIONS {Note: Include Facil;,,, Summarv and Sketch\ Flow Control Tvne/Descriotion Water Qualitv T"ne/Descrintion IXI Detention Unlined pond, IXI Biofiltration Raingardens w/ UD bottom and sides lXJ Infiltration may infiltrate D Wetpool D Regional Facility D Media Filtration D Shared Facility D Oil Control IXI Flow Control Grasscrete, and 0 Spill Control BMPs porous pavements 0 Flow Control BMPs D Other 0 Other 2009 Surface Water Design Manual 1/9/2009 4 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS D Drainage Easement D Cast in Place Vault D Covenant IXJ Retaining Wall D Native Growth Protection Covenant D Rockery> 4' High D Tract IXJ Structural on Steep Slope D Other D Other Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledg the information provided here is a.,:curate. Si ned/Date 2009 Surface Water Design Manual 5 l/9i2009 VANTAGE POINT APARTMENTS The infonnation indudad on lhis map has been compiled by King County staff from a variety of sources and is subject to change without notice. King Col.flty mak88 no representations or warranties, expr8SS or implied, as to accuracy, completeness, timeliness, or rights to Ille use of such infonnation. w This document Is not Intended for use 88 8 survey product. King County shall not be liable for any general, special, ind1ract, incidental, or consequential ". K·ang County damages induding, but not limited to, lost revenues or lost profits resulting from Ille use or m,suse of Ille infonnation contained on 111,s map. /lny sele of this map or information on this map Is prohibited except by written permission of King County. Date: 10/31/2013 Source: King County iMAP -Stormwater (http://www.metrokc.gov/GISIIMAP) CJ" 3: ,:;, vi z 0 i= cS z 0 u 0 z i= V) x w :;:::::: CJ) "' ._ ::::, CJ" G:: a::: F N I N ~ ........ 10 n LL. 0 I ;:::!-8 2x ;g ........ ~(./) ~\C c::::, _J c::::, <( <( z ;:3-<( '2~ "'-_(/") 0 LL. LL. (l.)0 en _£ I §ID > -w co a::: co 3 ;;:; LL 5-........ o= "' 0 N n o.. ~ 0 IE i5 / 00 n LL. ;:: I /c.:> ··> x, Cl n u / I a... a... CD V) .~ <( ._ I ..c c.:> u> X / <;2 w a::: <( / E> 0.. (/") vi N<.!l .. > N X I / v .. ~"' o E N O C -"' 0 = ,.,.., LL. §~ --:, X \ _.., .. \I ... \'1 OFFSITE BASI N I ~I I I I I I I DRAWN BY CB CHECK ED BY AGC I' I 11 I I /1 ,1 ' I I, I '/ /1 DA TE 0 1 /27/2014 ... J OB No.:1 13188 _,,j _, I S C A L E: 1'' = 60' Consulting Engineers 1601 Fifth A venue, Suite 1600 Seattle, Wash ington 98101-3665 (206) 622-5822 Fax (206) 622-8130 ED GRASS . . r. : J BASIN AREA ---il'MI ""'°' " • 1/T ...... --Ollll(;Nr:rrCXM;.WONIICJ,M D09I c..r (n,-,.ftJJ r M)N«)<t,I ltr~ cal II ,. 'I: ,. 00Mt. liDol II CAS IICMIC..7'(11/\1/11} KING COUNTY HOUSING AUTHORITY VANTAGE POINT APARTMENTS EXISTING CONDITIONS ~)8 0 -- // ~ / SHEET O'> 3C t, vi <( w 0::: ~ rn t / :::, :z O'> _J iZ 0...1 0::: ..... E-3 0... N I ~,.,..., lo No ~,.,..., I ~ ::? / 0 "'<..:> /1..,._ rn I :t:::: <..') ..0 > :.C I X Cl w,.,..., -;:;-(.) ~-:::3-(/) ?a (1) r::: <3o 8,~ oU cc..:> Oz >r::: ~(/) 005< OOw 5.,....-, /<..:> QI..,._ lf) I ~§; ~x 1 .,....-, 5o 0 (/) ,.,..., ~<..:> /> .. x x ,,,,-- 0 (/) I §32 I Cl ,.,..., u ~-·.::: ..c ~ 0 I 0... B5 <( I c..::> > X / E B; c.. I 0 c..::> "'> NX I / V V 5 E N 0 ai g~ C <V 0 ... -:, X ~ "'\;-4 >r<~~~ // "' I - // I \ / I I / I \ I \ ~ '\ \ I I I r, l -t-t DRAWN BY CB CHEC KED BY AGC 0 1 ·1\ 11 1: I i! / l~ I ~I .,. I I ~, ~~"" i --=, \ ~~' l I \ I ~,(/) "d J OB No . :1 13188 S C A L E: 1" = 60 ' ~--·---·····--. --~' ·-~~-.. -· ... I I I __ 111 l llt [-0-~U If~ Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, Washington 98101 -3665 {206) 622-5822 Fax (206) 622-8130 [Jill ~ ~ r--1 I __ .J I= I r.:) --~l'UloCMlllll•/'l"~ 01tC11,-,,·(0IC1o11;1t .. C.,,X O(MI C,7' (II/Ml/11; ..... ,.,~ ... ,tr .... J Cl9C, .. ~ 11 ~ c:oc;.. ..,., .. c.oa: / ODIi! a.7 ('lt!'•/12) PERv10U S LANDSCAPE PERMEABLE ASPHALT PAv1NG GRASSCRETE PAv1NG CA TCHMENT AREA ONSITE DETEN TION BYPASS ARE A BASIN AREA KING COUNTY HOUSING AUTHORITY VANTAGE POINT APARTMENTS FIGURE 3. DRAINAGE BASINS 0 / ,-· -3a--__ _ I -~•tr"f;"'~ ,;ct ~'"'" , .. = NC· --~~\ 'S8 30 / 60 / • I 3 / SHEET 47' 26' 36" 47° 26' 23" ~ J, ~ g "' J, ~ I. 'Tl !11'5 C ::a 111; • V, 0 -r- V, N A 560.100 560.160 560100 560160 560220 Map Scale . 1:2,800 if printed o n A size (8 .5 " x 11") sheet C usto m Soi l R es o urce Report Soil Map 560280 560340 560400 -----====::::11---------=========Meters 0 35 70 0 150 300 140 600 21 0 Feet 900 4 7' 26' 36" 47' 26' 23" 560460 560520 560580 0, ;,: -0 (./) vi >- _J <t z <t w >- vi LL LL 0 lf) w 0::: =:) <..'.) C: ;::::::: (/) ~ :::, er> ;_:;:: 0::: F C'-.J I C'-.J I n 0 N ___...... ~ ,Q ..c >< w ___...... 0 0 <( u ___...... C: <D <3 <D 0, 2 C: g -CXJ ~------n '= -CD /:c ox lf) w N n CD -f- l <..'.) -> Ox 0 '.'.::___...... -o ___...... c.n x§:2 CD X ___...... 0.. c.n <..'.) > X ·~ ........... ..c -u :r: 0.. 0.. c.n <t ~ DRAWN BY _:: CB [ i:;; CHECKED BY r,; I "'.: §:2 AGC C'-.J X DESIGNED BY CB APPROVED BY MAV I ___...- -st-•. -<D o E C'-.J 0 DATE 01/27/2014 C: -<D 0 = t0 LL C: <ii 0 ~ -:, X J O B No . :113188 --- S C A L E: 1" = 100' DOWNSTREAM FLOWP A TH ABOVE GROUND STRUCTURE Consulting Engineers 1601 Afth Avenue, Suite 1600 Seattle, Washington 98101-3665 (206) 622-5822 Fax (206) 622-8130 a; I!; MODIFIED PIPES IN ROW .... KING COUNTY HOUSING AUTHORITY VANTAGE POINT APARTMENTS FIGURE 5. OFFSITE ANALYSIS ;ffi 0 50 100 SHEET Basin: GREEN RIVER Symbol Drainage Component Type, Name. and Size see map Type: sheet flow, swale. stream, channel, pipe, pond; Size: dlamater, surface area VARIES VARIES OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2 Subbasin Name: PANTHER CREEK Subbasin Number: Drainage Slope Distance Existing Potential Observations of field Component from site Problems Problems inspector, resource Descriotion dischame reviewer. or resident drainage basin, vegetation, % % ml= 1,320 ft. constrictions, under capeclty, ponding, bibutary area, likelihood of problem, covar, depth, type al sensitive overtopping, flooding, habitat or organism overflow pathways, potential impacts area, volume destruction, scouring, bank sloughing, sedimentation, incision other erosion CITY CONV SYSTEM VARIES 0-1210' NONE NONE NO EVIDENCE OF FLOODING TRIB TO PANTER CREEK VARIES 1210'-1320' NONE NONE NO EVIDENCE OF EROSION 1/9/2009 Chris Borzio From: Sent: To: Gary Fink [GFink@Rentonwa.gov] Wednesday, December 11, 2013 6:57 AM Chris Borzio Subject: RE: Down Stream Drainage History -17901 105th Pl SE, Renton Thanks Chris, I'm familiar with the crossing at lOS'h. We have no reported drainage issues along this path within the X mile range. Best Regards, Gary Fink City of Renton Utility Systems Division -Surface Water Utility Phone:(425) 430-7392 I Fax:(425) 430-7241 GFink@RentonWa.gov --------1t~J1tu11 (~) From: Chris Borzio (mailto:Chris.Borzio@kpff.com] Sent: Tuesday, December 10, 2013 5:02 PM To: Gary Fink Cc: Alberto Cisneros Subject: RE: Down Stream Drainage History -17901 105th Pl SE, Renton Gary, That culvert you mentioned is actually on a different leg of the creek than the flowpath from my site. My site's flow path crosses Carr just west of lOS'h Pl SE. The outfall structure was a large square precast vault with a 36" CMP pipe outfall to the creek. Thank you, Christopher Borzio, PE, LEED Green Associate Civil Engineer KPFF Consull1nr;, Engineers O (286) 622-5822 C (206) 926-0418 1(JQ1 F1~th Avenue 1 Suite 1600 F: (706) 622-8130 Seattle Washington 98101 chris.borzlo@kpff.com www.kpff.com ~ Please consider the environment before printing this message From: Chris Borzio Sent: Tuesday, December 10, 2013 2:04 PM To: 'Gary Fink' Cc: Alberto Cisneros Subject: RE: Down Stream Drainage History -17901105th Pl SE, Renton Gary, The Carr Road crossing is actually just at the end of my X mile review. Is it safe to say that the 2008 work has taken care of the flooding problem? I hiked down the embankment to the outlet of that culvert, see attached photo, it seemed to be in good shape. The creek bottom was cobbles without side soughing as far as I could tell. 1 Thank you, Christopher Borzio, PE, LEED Green Associate Civil Engineer KPFF Consulting fngineers 0: (206) 622-5822 D:(206) 926-0418 1601 Fifth Avenue, Suite 1600 F: {206) 622-8130 Seattle Washington 98101 chris.borzio@kpff.com www.kpff.com ~ P!ease consider the environment before printing this message. From: Gary Fink [mailto:GFink@Rentonwa.gov] Sent: Tuesday, December 10, 2013 1:51 PM To: Chris Borzio Subject: Down Stream Drainage History -17901 105th Pl SE, Renton Good Afternoon Chris, Sorry to run a bit late on this information. Review of downstream drainage for the property located at 17901105th Pl SE did not identify any significant drainage issues. Just beyond the Y.-mile review area, we had localized flooding at the Panther creek crossing of Carr Rd. The culvert at this location was replaced in late 2008. Let me know if you need further information. Best Regards, Gary Fink City of Renton Utility Systems Division -Surface Water Utlllty Phone:(425) 430-7392 I Fax:(425) 430-7241 GFink@RentonWa.gov r J Cttyof. ~ -------1~~.tlrDlJ ~1 2 en a. TI vi ~ .a! :,: :::, <( w f"c U) o_ => "' w "' => '-' 5- ~ i" ~ en i..:: "' E, N I N I n 0 N ,,- ~ ,e = X ';;!- 0 0 <( < C "' [5 "' en .:0 C ~ "" "" ;;c; / 0 "' N n ' s,,- oo n uo -0 ,,-> xx ,,- '-' ~ I ~ ,,- CD U) ~ <( ·.:::: w = "' u <( ,,- B, 5' X ,,- E G; =, c---'-' ~~ I __,- -tj-<l) o E N o ~ g~ C © 0 -~ X DRAWN BY CB CHECKED BY AGC MM DESIGNED BY CB APPROVED BY MAV JOB No. :113188 ,, ,~ , CB -1200 :l:lt; r PA 0.000 AC 1 ~ IA 0.000 AC . ,~ , START BACl<WA 1ER ANAL YS1S "tl-¥Jtli'it. )! ,, '2/J.s. .. <(., Jc ii-. ' CB -1201 PA 0.000 AC 1 • IA 0.000 AC I ~I SllE DISOlARGE POINT I L CB f81)57 1 ' -· PA 0.053 AC .,,1·,. · .. ;.· IA 0.2~ AC iii :·1·' "J :•,' : ' 1• r, · ~ ...... 1, 2H: 1'1< , 1! 111 i 1 1 . 1.t' !I: 11 ·11 ! . 1 , .• ,,'. __ ... ;J-J .. ' ,,-,,, '' ,W~1> 111 .l, -', ,1 """}, i !11 \, ' ·-I lj , : ' : !' ; ! ! 1111,.' ,1,1~; ,, 1 '. ··: ~ , ,~11! -.0"-<>'"' "':.'..~""" ' ' ' l -, . .,_ / :' I 'I ' ----':;';. •• ,,,,,,,, ASIN i, , 1 , -1 ~--,!i.'c~.". SUBB t·. ~\., ',, « ,,! -1 ,-::;·,, ;,;,.,, CB f/059 -~--~ ~-_ ~-=-~-- . , \ '' ·'"""" -= ' ?IC·' -SI ' \'\,\' --:: . • •• C • • .... " • C ., · ' ~ ..... ;,,;- ' ·~:.:-~~:.:.:~~-~ ,,_ --~ S C A L E: 1" = 60' _---_i 1-l '"'·'",:-;,w .. --~---:::::-,.,,a:3...~...,.,.------.s:~.aa·::aa-. 8E *1'Tll ir: ·,.:..:,~.·· Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, Washington 98101-3665 (206) 622-5822 Fax {206) 622-8130 F<i _I PER"10US f,RfA SUBBASIN f,RfA ri-,,,.. ce (12:!IJ -==·=·- \~ t ;;i i CB f/376 ~j? t-•r-···· , --I .• \ -----< .• ~._'. PA. 0.020 ~. ;-·; .L'.c° ~---.. , . . . . .. . .·. ~ IA ~ A£. ··'.-zt: _J -\'\'f. c,C, • , ~w;.;._·=· ,'· . ' ·. -___ ..... ~r4 1!ili0.t,:'>,t;~·:/-;~, ~-·;,c~,c·:-·~· ,r1:.;;;;z"',:,-.:s!o~. . , /: ~.· .... , ... -,,~,....,.-. _,' ·"o .. , '"' "• ··:···· ... ,, ./ ' ?,~ NORTH EB 0 30 60 KING COUNTY HOUSING AUTHORITY SHEET VANTAGE POINT APARTMENTS FIGURE 6. UPSTREAM ANALYSIS Appendix B Drainage Facility Documentation and Design Vantage Point Apartments Technical Information Report Appendix B KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL STORMWATER FACILITY SUMMARY SHEET Number TBD -------- DDES Permit (provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Overview: Project Name _:_V:...:AN:.:.T.:.:.A.:..:G=-=E:...:P--=O:..clN-'-T'--'A...::P_:._A.:.:.:R:..:.T:..:.M::E'--'NT.:..:S:...._ ___________ Date 12/12/2013 Downstream Drainage Basins Major Basin Name _G_R_E_E_N_R_IV_ER _______ _ Immediate Basin Name PANTHER CREEK Flow Control: Flow Control Facility Name/Number _,D:..:E:..:T.=Ec:..:Nc:.T,.,10:..:N.:....:...PO"-'-'N-=D ______ _ Facility Location 17901105th Place SE, Renton, Washington 98055 If none, Flow control provided in regional/shared facility (give location) ______________ _ No flow control required Exemption number General Facility Information: Type/Number of detention facilities: Type/Number of infiltration facilities: 1 ponds ponds vaults tanks --- tanks trenches --- Control Structure Location Type of Control Structure FLOW RESTRICTING ORIFICE TEE 2 Size of Orifice/Restriction: No.2 No.3 No. I 1-1/2" No. 4 ______ _ 1-1/16" Number of Orifices/Restrictions Flow Control Performance Stapdard LEVEL 2 (FORESTED CONDITION) 2009 Surface Water Design Manual 1/9/2009 1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Live Storage Volume __ 2_5'---,0_5_4_C_F ___ Depth 4 FT Volume Factor of Safety 1.0 Number of Acres Served 3.32 AC --------- Number of Lots __ eel ______ _ Dam Safety Regulations (Washington State Department of Ecology) Reservoir Volume above natural grade 0, POND CUT INTO EX GRADE Depth of Reservoir above natural grade _0'---------- Facility Summary Sheet Sketch All detention, infiltration and water quality facilities must include a detailed sketch. (11 "xl 7" reduced size plan sheets may be used) 2009 Surface Water Design Manual 2 1/9/2009 • • • • j ,; f J i • a I j J ! • • ; ..,_CB Dff 2 48""-~" OIU ,,dM STA 21+l5.26, 55.41' RT. Rllil 38251 6" & 8" 1E 376.39 (E) tH STORM DRAINAGE NOTES: ~ ---=-~~.~~ ~-.ff.L_----____ ~--_ ---~--------. -=-~~--~-IE 3:~_:~::~ D'PE 1 CB -BP2 RAIN GAROEN .: 1 '\ ;~/ ... , 6' PERf P,Ve/~PE ~ ~j. RAIN GARD91 -I . "-J i HORIZOOTAL CONTROL FOR SlRUCTURES ADJACENT TO CURB IS PRO'YlDED BY STATIOO ctU. CONTRACTOO SHALl LAY OUT CURB UNE TO DETERMINE EXACT om;u NECESSARY FOR OOTSIDE OF FRAME TO AUGN 'MTH FACE OF CURB. HORIZONTAL CONTROL FOR STRUCTURES NOT ADJACENT TO CURB REFERS TO CENlER OF STRUCTURE. 'f' ~, 1~ @ OVERFLOW STRUCTURE Rllil 3n.OO ; •I. :. ,: \ -, \~ I ,) ) I'/ I I '"'-'. I 105TH PLACE SE ----------- ' ' ~ " '{,, -·--....o-u.. J.L~'-m"" I LPPER WSEL 37'!Mi9 BOTTOt.i ELEV 378.M RWJIR£D BOTIOM AR~ 67 SF --+------ 20+00 0 0.411 'ElCB-106 STA 41+68.59 RIM .384.07 B" IE :513267 (E) IN 12" IE 382.34 (S} OUT -, 6" POC FOR MECH SUMP AND PUMP IE 3n.O 11.i_ u· fl!_ UPPER WSEL 381 • .0- -~filV 380.40 !Ml£ REQUIRED BOTIOO AREA 1,141 SF ;>t, STA 4J+-2o.65 RIM ;m.86 12" IE 381.71 Tl!ENCH DRAIN Rlt.i ELEVA TIOOS SHOv.t,1 REFER TO CENTER Cl'" TRENCH DRAIN CATCH BASIN. REFER TO GRAOJNG PLAN AND AUGNt.iENT PROFlLES FOR REMAINING TRENCH GRAlE EllVATICt.lS. ·3a --- TYPE 1 ~~ STA 44+BB.42 RIW 385.37 •8 8" IE 381.33 {SE) IN ~ ·1 --1r1E"JB1.oo / , , / , , / / , , I I I I _L 1 ~ ---~ ------, --~--________ :.,_c...-----,,----------------_/, ----~-------------- L-----~ " " s: i ~ §, t2 ~ ~ ~~---- 0-. -.!. :g ~ ~~~ ii ~ 0) ti 1 8 g]: i!~ ~" ' @: i"" l;: ... ~ a:::~ ~&~ en ts t-f-< z ~ >-~ UJ -f-~ iJj 12~ t-~ ~ ~ C \_Signatur~sf O~-ili!~ <( f-(!) f-z z (J) w -w ., t-Cl:'. ~ ~ Zw O><: -CJ) :c: a:::: 0 w ~ '8: a_ ~ z Cl:'. UJ -'l ::::,w Cl.. 0 > ('.) :,: O 0 <( f-(!) Cl ~ ::g ::z z ~ -< z ""C, <( ~ C, C, <O >~ ~ --DESIGN DEV. 11/CWl3 COO!UllNATION 01115114 ~ ~I - (\J 00 ~ -·---· oj DRAINAGE PLAN (/) I-z w= AS NOTED ~ PLOTl:ltl.TE 01/28/14 --MAV :::) "'" -AGC §:: TAO I-C6.0 :i: a: w NOTFOR 1nch•201eet a. CONSTRUCTION Of1B-ll9 (90l) XDd ll{lq-ll9 (9Dl) i99f-i0IB6 uo+6u11.1srw. 'amcws 0091 .111ns '<mufJJ\1" 1m1:1 /09J SJ@@Uf6UJ Ou,runsUO:J mg r ~~~ ! (~I I ...... 1 .. 1 I -TJ"TJ r -'1 t ~ ! (~II "" . 'I 'c~-!1 ! ! i ,1 • ,! ,, ! Oil Of ' J ~ I >Ii -k ,11 ~ ''l ~~! l> I> " ,, 'vM \fllM)ln:j: '1S3M )ll:l'vd l:131\00N'v 009 A.lll:IOHl(JJ 8N1SnOH A.lNnoo clNl)I I NOlclNIHS'vM 'ffil1N3l:I '3S 30\fld H190 ~ (06H 0 S1N3VJ1~V lNIOd 38VlNV/\ • h !' al I i I ' "' ' l ~II '! lli • '1 1!; ~1 8 I ~ " ~ " ~ ~ I 7;~ ·1 ( ). ,' ;,; !ii\\,/,.~ jl ~'~! i ! t:. ·~ I •• '::! I ~ i~ 'I'. • Ii I ! /~ /b_1 u l <t~YI i t !i I etTJ ( ' i ll '~\; ) l -•, J •'j;; ! Yi i 11 i ' fl Ii lj Jl •! !Ji }i! it ::. 0 ~ (/} ::::, (.) ~ !GD i ' ~ ~ e • (/} 0 ;e -' <( ~~ ~ Lu •• Cl ~E (/} S• ::::, " ~; 8z ~; :z K• ::5 -' i Lu (.) ~-(/} •• ::. ~~ ~~ © ( i II I ! I I i ! ! ! I ! ' i l ' !~~ r',-,-------j_---, -. ! I ' ' •! ~~ I !11 i I I I • hi I l 11! J ' •I I 'j'•iil• I 'IT 1:1 r 1 I !•!1:I} -~ I Cl... 0 Ii I • • • • • ~-~~ ~o: ~~ @) "" u... "" Lu "" "" <( CD !a (/} o" CD Lu Cl :z "" (/) Lu Cl !a :z 0 ~ u <( Cl... ::. 0 u Cover Type 8 ITill Grass ~ Total ~ C 0.742 AC 2.969 AC BMP 1s Pervious Pavmt (50% imp 50% grass) Grasscrete (All Grass) WSEL ~~ ~ m o~ ,: :S ~o -c ;;: ~ ~ )> ,; a: 2 )> ~,: ,; ~ C ~ 0 0.136 AC 0.172 AC 0.209 AC -~ ~ ,: 0~ ,: )> ~ ~ =i ~ m~ ~ ,: ~~ ~~ C ~ m 0 POSTDEV=DET Time Series Till Grass Impervious Total 0.982 AC 1.778 AC 2.760 AC C---< g:: s:: om -~ zm ~"' nm ~~ ---< ~ WSEL Time Series Impervious X:\113001-113250\113188 (Vantage Glen)\PROJECT DOCUMENTS\Storm Drainage\Detention & Conveyance Calculatrons\KCRTS\Cover Types.xis 0.209 AC INPUTS. exc KCRTS Program ... File Directory: C:\KC_SWDM\KCRTS\ [C] CREATE a new Time Series ST 3.20 0.00 0.000000 Ti 11 Forest 0.00 0.00 0.000000 Ti 11 Pasture 0.00 0.00 0.000000 Till Grass 0.00 0.00 0.000000 outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 outwash Grass 0.00 0.00 0.000000 Wetland 0.00 0.00 PREDEV.tsf 0.000000 Impervious T 1.00000 T [CJ CREATE a new Time Seri es ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 3 .20 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 wetland 0.00 0.00 0.000000 Impervious EXISTING_GRASS.tsf T 1. 00000 T [C] CREATE a new Time Series ST 0.00 0.00 0.000000 Ti 11 Forest 0.00 0.00 0.000000 Ti 11 Pasture 0.98 0.00 0.000000 Ti 11 Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 1. 78 0.00 0.000000 Impervious POSTDEV_DET.tsf T 1. 00000 ·T [CJ CREATE a new Time Seri es ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Ti 11 Pasture 0.00 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 outwash Pasture 0.00 0.00 0.000000 outwash Grass 0.00 0.00 0.000000 wetland 0.21 0.00 0.000000 Impervious POND_WSEL.tsf T 1.00000 T [CJ CREATE a new Time series ST 0.00 o.oo 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.21 0.00 0.000000 Till Grass Page 1 0.00 o.oo 0.00 0.00 0.15 POSTDEV_BYP. tsf T 0.00 0.00 0.00 0.00 0.00 INPUTS.ex( 0.000000 outwash Forest 0.000000 Outwash Pasture 0.000000 outwash Grass 0.000000 Wetland 0.000000 Impervious 1.00000 T [C] CREATE a new Time Seri es ST o.oo 0.00 0.000000 0.00 0.00 0.000000 0.98 0.00 0.000000 0.00 0.00 0.000000 o.oo 0.00 0.000000 0.00 0.00 0.000000 0.00 0.00 0.000000 1. 78 0.00 0.000000 POSTDEV_DET_l5MIN.tsf T 1.00000 F [C] CREATE a new Time Series ST 0.00 0.00 0.000000 0.00 0.00 0.000000 o.oo 0.00 0.000000 0.00 0.00 0.000000 0.00 0.00 0.000000 0.00 0.00 0.000000 0.00 0.00 0.000000 0.21 0.00 0.000000 POND_WSEL_l5MIN.tsf T 1. 00000 F [T] Enter the Analysis TOOLS Module [P] compute PEAKS and Flow Frequencies PREDEV.tsf PREDEV.pks [P] Compute PEAKS and Flow Frequencies EXISTING_GRASS.tsf EXISTING_GRASS.pks [Pl compute PEAKS and Flow Frequencies POSTDEV_DET_l5MIN.tsf PD5TDEV_DET_l5MIN.pks [R] RETURN to Previous Menu [A] ADD Time series POND INFLOW. tsf 2 POND_WSEL.tsf 1.00000 0.00000 POSTDEV_DET.tsf 1.00000 0.00000 [A] ADD Time Series POND INFLOW_l5MIN.tsf 2 POND_WSEL_l5MIN.tsf 1.00000 0.00000 POSTDEV_DET_l5MIN.tsf 1.00000 0.00000 [A] ADD Time Series Ti 11 Forest Til 1 Pas tu re Ti 11 Grass outwash Forest Outwash Pasture outwash Grass Wetland Impervious Ti 11 Forest Till Pasture Till Grass outwash Forest Outwash Pasture outwash Grass Wetland Impervious Page 2 INPUTS. exc CONSTRUCTION.tsf 2 PONO INFLOW.tsf 1.00000 0.00000 POSTDEV_BYP.tsf 1.00000 0.00000 [Tl Enter the Analysis TOOLS Module [Pl compute PEAKS and Flow Frequencies POND INFLOW.tsf POND IN FLOW. pks [Pl compute PEAKS and Flow Frequencies POND INFLOW_l5MIN.tsf POND INFLDW_l5MIN.pks [Pl compute PEAKS and Flow Frequencies CONSTRUCTION.tsf CONSTRUCTION.pks [R] RETURN to Previous Menu [S] Route through a SINGLE (1) outlet Reservoir CHECK POND.RSl pond inflow.tsf CHECK POND OUT.tsf [A] ADD Time Series CHECK POC.tsf 2 CHECK POND OUT.tsf 1.00000 0.00000 POSTDEV_BYP.tsf 1.00000 0.00000 [T] Enter the Analysis TOOLS Module [P] compute PEAKS and Flow Frequencies CHECK POC.tsf CHECK POC.pks [Pl compute PEAKS and Flow Frequencies CHECK POND OUT.tsf CHECK POND OUT.pks [CJ COMPARE Flow Durations predev.tsf check poc.tsf DURATION.PRN F 0.445000E-01 0.202 14 [R] RETURN to Previous Menu Page 3 Flow Frequency Analysis Time series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.202 2 2/09/01 18:00 0.055 7 1/06/02 3:00 0.150 4 2/28/03 3:00 0.005 8 3/24/04 20:00 0.089 6 1/05/05 8:00 0.155 3 1/18/06 21:00 0.131 5 11/24/06 4:00 0.258 1 1/09/08 9:00 Computed Peaks PREDEV. pks -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0.258 1 100.00 0.990 0.202 2 25.00 0.960 0.155 3 10.00 0.900 0.150 4 5.00 0.800 0.131 5 3.00 0.667 0.089 6 2.00 0. 500 0.055 7 1. 30 0.231 0.005 8 1.10 0.091 0. 239 50.00 0.980 Page 1 Flow Frequency Analysis Time Series File:pond inflow.tsf Project Location:sea-Tac ---Annua 1 Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0. 571 6 2/09/01 2:00 0.470 8 1/05/02 16:00 0.684 3 2/27/03 7:00 0. 514 7 8/26/04 2:00 0.618 4 10/28/04 16:00 0.606 5 1/18/06 16:00 0.748 2 10/26/06 0:00 1.15 1 1/09/08 6:00 computed Peaks POND IN FLOW. pks -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 1.15 1 100. 00 0.990 0.748 2 25.00 0.960 0.684 3 10.00 0.900 0.618 4 5.00 0.800 0. 606 5 3.00 0.667 0. 571 6 2.00 o. 500 o. 514 7 1. 30 0. 231 0.470 8 1.10 0.091 1.01 50.00 0.980 Page 1 Retention/Detention Facility Type of Facility: Side Slope: Pond Bottom Length: Pond Bottom Width: Pond Bottom Area: Top Area at 1 ft. FB: Effective Storage Depth: Stage O Elevation: Storage Volume: Vertical Permeability: Infiltration Pon=d'--~~~~ 3.00 H:lV 106.50 ft 40.00 ft 4260. sq. ft 9555. sq. ft 0.219 acres 4.00 ft 0.00 ft 24840. cu. ft 0.570 ac-ft 240.00 min/in Permeable Surfaces: Bottom & Sides Riser Head: 4.00 ft Riser Diameter: Number of orifices: 12.00 inches 2 -u ~ C z ot:!vi "'T1G'lz2Q -rn Cl Gl ~ 0 :,:, 0 0 ;,:, s: V, )> 1-1'2::o ::j~"'Tl~"'C a::oo· ::o 2-<::0V')m ::o l> l> rn C )> z n rn s: -I c:, -I n -m cIZ )> rn )> ,-n ::o "' -< Orifice# Height (ft) 0.00 2.55 Diameter (in) 1. 06 1.50 Full Head Discharge (CFS) 0.061 0.073 Pipe Diameter (in) 1 2 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage (ft) (ft) (cu. ft) (ac-ft) 10.001 0.00 0. 0.000 0.01 0.01 43. 0.001 0.02 0.02 85. 0.002 0.03 0.03 128. 0.003 0.04 0.04 171. 0.004 0.06 0.06 257. 0.006 0.07 0.07 300. 0.007 4.0 Discharge Percolation (cfs) (cfs) 10. ooo I 0.00 0.003 0.02 0.005 0.02 0.006 0.02 0.006 0.02 0.007 0.02 0.008 0.03 -c, 0 V, n zl>--1 0 -I ~ ~ ~ z I ;,:, "Tl -ti') C rn G) (./') 1--1. (./') )> cOd06 ;,:, ;,:, - )> :;; ;,:, z Cl :::!n~ni:n 0 m , I G'l Z -rnl> n n ::o :!:; "' Gl rn rn Surf Area (sq. ft) 4260. 4269. 4278. 4286. 4295. 4313. 4322. 0.08 0.08 344. 0.008 0.009 0.03 4331. 0.09 0.09 387. 0.009 0.009 0.03 4339. 0.19 0.19 825. 0.019 0.013 0.03 4428. 0.29 0.29 1273. 0.029 0.016 0.03 4518. 0.39 0.39 1729. 0.040 0.019 0.03 4608. 0.49 0.49 2194. 0.050 0.021 0.03 4699. 0.59 0.59 2669. 0.061 0.024 0.03 4 791. 0.69 0.69 3153. 0. 072 0.025 0.03 4884. 0.79 0.79 3646. 0.084 0.027 0.03 4977. 0.89 0.89 4148. 0.095 0.029 0.03 5071. Io. 99 I 0.99 4660. 0.107 10. 030 I 0.03 5165. 1. 09 1. 09 5181. 0 .119 0.032 0.03 5261. 1.19 1.19 5712. 0.131 0.033 0.03 5357. 1. 29 1. 29 6253. 0.144 0.035 0.03 5454. 1. 39 1. 39 6803. 0.156 0.036 0.03 5551. 1. 49 1. 49 7363. 0.169 0.037 0.03 5650. 1. 59 1. 59 7933. 0.182 0.039 0.03 5749. 1. 69 1. 69 8513. 0.195 0.040 0.03 5848. 1. 79 1. 79 9102. 0.209 0.041 0.03 5949. 1. 89 1. 89 9702. 0.223 0.042 0.04 6050. 11. 99 I 1. 99 10312. 0.237 10. 043 I 0.04 6152. 2.09 2.09 10933. 0.251 0.044 0.04 6254. 2.19 2.19 11563. 0.265 0.045 0.04 6358. 2.29 2.29 12204. 0.280 0.046 0.04 6462. 2.39 2.39 12856. 0.295 0.047 0.04 6566. 2.49 2.49 13518. 0.310 0.048 0.04 6672. 2.55 2.55 13920. 0.320 0.049 0.04 6736. 2.57 2.57 14055. 0.323 0.050 0.04 6757. 2.58 2.58 14122. 0.324 0.051 0.04 6767. 2.60 2.60 14258. 0.327 0.054 0.04 6789. 2.61 2.61 14326. 0.329 0.057 0.04 6799. 2.63 2.63 14462. 0.332 0.061 0.04 6821. 2.64 2.64 14530. 0.334 0.066 0.04 6831. 2.66 2.66 14667. 0.337 0.070 0.04 6853. 2.68 2.68 14804. 0.340 0. 072 0.04 6874. 2.78 2.78 15497. 0.356 0.080 0.04 6982. 2.87 2.87 16130. 0.370 0.087 0.04 7079. 12.971 2.97 16843. 0.387 lo. 093 I 0.04 7188. 3.07 3.07 17568. 0.403 0.098 0.04 7298. 3.17 3.17 18303. 0.420 0.103 0.04 7408. 3.27 3.27 19049. 0. 43 7 0.107 0.04 7519. 3.37 3.37 19807. 0.455 0 .112 0.04 7631. 3.47 3.47 20576. 0. 472 0 .116 0.04 7744. 3.57 3.57 21356. 0.490 0.120 0.05 7857. 3.67 3.67 2214 7. 0.508 0.123 0.05 7971. 3. 77 3. 77 22950. 0.527 0 .127 0.05 8085. 3.87 3.87 23764. 0.546 0 .131 0.05 8201. 3.97 3.97 24590. 0.565 0 .134 0.05 8317. 14. oo I 4.00 24840. 0.570 lo .135 I 0.05 8352. 4.10 4.10 25681. 0.590 0.446 0.05 8469. 4.20 4.20 26534. 0.609 1. 010 0.05 8587. 4.30 4.30 27398. 0.629 1.740 0.05 8705. 4.40 4.40 28275. 0.649 2.540 0.05 8825. 4.50 4.50 29163. 0.669 2.820 0.05 8945. 4.60 4.60 30064. 0.690 3.080 0.05 9065. 4.70 4.70 30976. 0. 711 3.320 0.05 9187. 4.80 4.80 31901. 0.732 3.540 0.05 9309. 4.90 4.90 32838. 0.754 3.750 0.05 9431. 5.00 5.00 33788. 0. 776 3.950 0.06 9555. 5.10 5.10 34749. 0.798 4 .130 0.06 9679. 5.20 5.20 35723. 0.820 4.310 0.06 9804. 5.30 5.30 36710. 0.843 4.480 0.06 9930. 5.40 5.40 37709. 0.866 4.650 0.06 10056. 5.50 5.50 38721. 0.889 4.810 0.06 10184. 5.60 5.60 39746. 0.912 4. 960 0.06 10311. 5. 70 5.70 40784. 0.936 5 .110 0.06 10440. 5.80 5.80 41834. 0. 960 5.260 0.06 10569. 5.90 5.90 42898. 0.985 5.400 0.06 10699. 6.00 6.00 43974. 1.010 5.540 0.06 10830. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft I 1 1.15 0.58 4.12 4.12 25891. 0.594 2 0.68 0 .11 3.25 3.25 18863. 0.433 3 0. 75 0.05 2.56 2.56 13979. 0.321 4 0.61 0 .11 3.34 3.34 19545. 0.449 5 0.57 0.19 4.02 4.02 6 0.62 0.04 1. 66 1. 66 7 0.51 0.04 1. 3 7 1. 37 8 0.47 0.04 1. 77 1. 77 Hyd R/D Facility Tributary Reservoir Outflow Inflow Inflow 1 0.58 0.12 ******** 2 0 .11 0.07 ******** 3 0.05 0.06 ******** 4 0 .11 0.06 ******** 5 0.19 0.06 ******** 6 0.04 0.05 ******** 7 0.04 0.04 ******** 8 0.04 0.04 ******** Route Time Series through Facility Inflow Time Series File:pond inflow.ts£ Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 1.15 CFS Peak Outflow Discharge: 0.584 CFS Peak Reservoir Stage: 4. 12 Ft Peak Reservoir Elev: 4.12 Ft 24997. 8324. 6683. 9004. POC Outflow Target Cale ******* 0.63 ******* 0.14 ******* 0.09 ******* 0.14 ******* 0.21 ******* 0.08 ******* 0.07 ******* 0.07 at 6:00 on Jan at 10:00 on Jan Peak Reservoir Storage: 25891. Cu-Ft 0.594 Ac-Ft Add Time Series:postdev_byp.tsf 0.574 0.191 0.153 0.207 9 in Year 8 9 in Year 8 Peak Summed Discharge: 0.625 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 50540 82.420 82.420 17.580 0.176E+OO 0.008 2254 3.676 86. 096 13. 904 0.139E+OO 0.014 2432 3. 966 90.062 9.938 0.994E-01 0.019 1852 3.020 93.082 6.918 0. 692E-01 0.024 1407 2.295 95. 3 77 4.623 0.462E-01 0.030 1174 1. 915 97.291 2.709 0.271E-01 0.035 610 0.995 98.286 1. 714 0 .1 71E-01 0.041 473 0.771 99.057 0.943 0.943E-02 0.046 278 0.453 99.511 0.489 0.489E-02 0.051 132 0.215 99. 726 0.274 0.274E-02 0.057 5 0.008 99.734 0.266 0.266E-02 0.062 7 0. 011 99.746 0.254 0.254E-02 0.068 3 0.005 99.750 0.250 0.250E-02 0.073 8 0.013 99.764 0.236 0.236E-02 0.078 13 0.021 99.785 0. 215 0.215E-02 0.084 10 0.016 99.801 0.199 0.199E-02 0.089 13 0.021 99.822 0.178 0.178E-02 0.095 16 0.026 99.848 0.152 0.152E-02 0.100 22 0.036 99.884 0 .116 0 .116E-02 0.105 16 0.026 99.910 0.090 0.897E-03 0 .111 20 0.033 99.943 0.057 0. 571E-03 0 .116 9 0.015 99.958 0.042 0.424E-03 0.122 11 0.018 99.976 0.024 0.245E-03 0.127 4 0.007 99.982 0.018 0.179E-03 0.132 5 0.008 99.990 0.010 0.978E-04 0.138 4 0.007 99.997 0.003 0.326E-04 0.143 0 0.000 99.997 0.003 0.326E-04 0.149 0 0.000 99.997 0.003 0.326E-04 0.154 0 0.000 99.997 0.003 0.326E-04 0.159 0 0.000 99.997 0.003 0.326E-04 0.165 1 0.002 99.998 0.002 0.163E-04 0.170 0 0.000 99.998 0.002 0.163E-04 0.176 0 0.000 99.998 0.002 0.163E-04 0.181 0 0.000 99.998 0.002 0.163E-04 0.186 0 0.000 99.998 0.002 0.163E-04 0 .192 0 0.000 99.998 0.002 0.163E-04 CHECK POND.RS! one outlet Reservoir Routing File Sta5e Dischar 5e stora5e Perm-Area (Ft (CFS (Cu-Ft (Sq-Ft) STAGE AND DISCHARGE 0.00 0.000 0. 4371. 1.00 0.030 5100. 5100. FROM POND DISCHARGE 2.00 0.043 10955. 5855. TABLE 3.00 0.094 17596. 6641. 4.00 0.135 25054. 7458. 0.00 Ft : Base Reservoir Elevation 150. 0 Minutes/Inch: Average Perm-Rate = 0.40 IN/HR Page 1 CHECK POND OUT.pks Flow Frequency Analysis Time Series File:check pond out.tsf Project Location:sea-Tac ---Annual Peak Flow Rates--- Rank Time of Peak -----Flow Frequency Analysis------- Flow Rate (CFS) 0.125 0.035 0.090 0.032 0.051 0.099 0.109 0.134 Computed Peaks 2 7 5 8 6 4 3 1 2/09/01 20:00 12/28/01 17:00 2/28/03 7:00 8/24/04 0:00 1/05/05 15:00 1/18/06 22: 00 11/24/06 7:00 1/09/08 12:00 --Peaks --Rank Return Prob (CFS) (ft) Period 0.134 3.99 1 100.00 0.125 3.77 2 25.00 0.109 3.37 3 10.00 0.099 3.13 4 5.00 0.090 2.92 5 3.00 0.051 2.16 6 2.00 0.035 1.37 7 1.30 0.032 1.14 8 1.10 0.131 3.91 50.00 Page 1 0.990 0.960 0.900 0.800 0.667 0. 500 0.231 0.091 0.980 Flow Frequency Analysis Time series File:check poc.tsf Project Location:sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.161 2 2/09/0118:00 0.064 7 1/05/02 16:00 0.121 5 2/28/03 3:00 0.058 8 8/26/04 2:00 0.075 6 1/05/05 8:00 0.131 4 1/18/06 20:00 0.147 3 11/24/06 4:00 0.208 1 1/09/08 9:00 computed Peaks CH ECK POC. pks -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 0.208 1 100.00 0.990 0.161 2 25. 00 0.960 0.147 3 10.00 0.900 0.131 4 5.00 0.800 0.121 5 3.00 0.667 0.075 6 2.00 0. 500 0.064 7 1. 30 0.231 0.058 8 1.10 0.091 0.192 50.00 0.980 Page 1 PONO INFLOW_l5MIN.pks Flow Frequency Analysis Time Series File:pond inflow_l5min.tsf Project Location:sea-Tac ---Annual Flow Rate (CFS) 0.947 0.666 2.01 0.763 1.12 1.13 1. 32 2.85 Peak Flow Rates--- Rank Time of Peak 6 8 2 7 5 4 3 1 8/27/01 18:00 1/05/02 15:00 12/08/02 17:15 8/23/04 14:30 11/17 /04 5: 00 10/27/05 10:45 10/25/06 22:45 1/09/08 6: 30 Computed Peaks -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 2.85 1 100.00 2.01 2 25.00 1.32 3 10.00 1.13 4 5.00 1.12 5 3.00 0.947~ 6 2.00 o. 763 \ 7 1.30 0. 666 ;' 8 1. 10 2.57 . 50.00 ,, 0.990 0.960 0.900 0.800 0.667 0. 500 0.231 0.091 0.980 \. VS6D rN StD1W1eA./1 PoNP 512,w& Page 1 CONSTRUCTION.pks Flow Frequency Analysis Time Series File:construction.tsf Project Location:sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.626 6 2/09/01 2:00 o. 512 8 1/05/02 16:00 0.751 3 2/27/03 7:00 0.556 7 8/26/04 2 :00 0.668 4 10/28/04 16:00 0.664 5 1/18/06 16:00 0.808 2 10/26/06 0:00 1. 26 1 1/09/08 6:00 computed Peaks -----Flow Frequency Analysis------- --Peaks Rank Return Prob (CFS) Period 1. 26 1 100.00 0.990 · 0.808 2 25.00 0.960 0.751 3 10.00 0.900 0.668 4 5.00 0.800 0.664 5 3.00 0.667 0.626 6 2.00 0. 500 0. 556 7 1. 30 0.231 o. 512 8 1.10 0.091 1.11 50.00 0.980 Page 1 POSTDEV_DET_l5MIN.pks Flow Frequency Analysis Time series File:postdev_det_lSmin.tsf Project Location:sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.848 6 8/27/01 18:00 2.60 1 100.00 0.990 0.601 8 1/05/02 15: 00 1. 82 2 25.00 0.960 1. 82 2 12/08/02 17:15 1.18 3 10.00 0.900 0.683 7 8/23/04 14:30 1.03 4 5.00 0.800 1. 03 4 11/17/04 5:00 1.01 5 3.00 0.667 1.01 5 10/27/05 10:45 0.848 6 2.00 0. 500 1.18 3 10/25/06 22:45 0.683 7 1. 30 0.231 2.60 1 1/09/08 6:30 0.601 8 1.10 0.091 computed Peaks 2.34 50.00 0.980 Page 1 EXISTING_GRASS. pks Flow Frequency Analysis Time Series File:existing_grass.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Fl ow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period o. 286 4 2/09/01 2:00 0.676 1 100.00 0.990 0.146 7 1/05/02 16:00 0.363 2 25 .00 0.960 0. 363 2 2/27 /03 7:00 0.293 3 10.00 0.900 0.060 8 8/26/04 2:00 0.286 4 5.00 0.800 0.158 6 1/05/05 8:00 0.263 5 3.00 0.667 0.293 3 1/18/06 16 00 0.158 6 2.00 0.500 0.263 5 11/24/06 3 00 0.146 7 1. 30 0.231 0.676 1 1/09/08 6 00 0.060 8 1.10 0.091 computed Peaks 0. 572 50.00 0.980 Page 1 DURATION.PRN Duration Comparison Anaylsis Base File: predev.tsf New File: check poc.tsf Cutoff Units: Discharge in CFS 30-Jan-2014 09:25 Nr mm ~(/\ oV> ~ I > z -----Fraction of Time----- Cutoff Base New %Change 0.044 0.95E-02 0.88E-02 -7.7 ---------Check of Tolerance-------) Probability Base New %Change ~~- 0.95E-02 0.044 0.043 -2.6 0.63E-02 0.056 0.050 -10.7 0.49E-02 0.069 0.057 -16.7 0.37E-02 0.081 0.064 -20.1 0.28E-02 0.093 0.072 -21.9 0.22E-02 0.105 0.081 -22.7 0.15E-02 0.117 0.096 -17.9 O.lOE-02 0.129 0.107 -17.0 0.62E-03 0.141 0.118 -16.6 0.34E-03 0.153 0.130 -15.3 0.21E-03 0.165 0.139 -16.2 0.16E-03 0.178 0.140 -21.1 0.98E-04 0.190 0.148 -22.2 0.056 0.63E-02 0.50E-02 -20.9 0.069 0.49E-02 0.31E-02 -36.2 0.081 0.37E-02 0.22E-02 -40.1 0.093 0.28E-02 0.16E-02 -42.5 0.105 0.22E-02 O.llE-02 -49.3 0.117 0.15E-02 0.62E-03 -57.8 0.129 O.lOE-02 0.34E-03 -66.1 0.141 0.62E-03 0.15E-03 -76.3 0.153 0.34E-03 0.49E-04 -85.7 0.165 0.21E-03 O.OOE+OO -100.0 0.178 0.16E-03 O.OOE+OO -100.0 0.190 0.98E-04 O.OOE+OO -100.0 There is no positive excursion~ Maximum negative excursion= 0.024 cfs (-24.0%) occurring at 0.101 cfs on the Base Data:predev.tsf and at 0.077 cfs on the New Data:check poc.tsf "" r om ,c (/\ "' V\ :i > z Page 1(1) ~ r m <> >~ co mz v, m A I 0> r " 0 " KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Water Quality: RAIN GARDEN -1 Type/Number of water quality facilities/BMPs: biofiltration swale large) above --- (regular/wet/ or continuous inflow) large) --- --- combined detention/wetpond (wetpond portion basic or large) combined detention/wetvault ___ filter strip ___ flow dispersion ___ farm management plan ___ landscape management plan ___ oil/water separator (baffie or coalescing plate) Liner? --------- catch basin inserts: --- Manufacturer ___ sand fi1 ter (basic or large) ___ sand filter, linear (basic or ___ sand filter vault (basic or sand bed depth'----(inches) stormwater wetland --- ___ storm filter ___ wetpond (basic or large) wetvault --- ___ Is facility Lined? If so, what marker is used X RAIN GARDEN -------------------- ___ pre-settling pond ___ pre-settling structure: Manufacturer ------------------- ___ high flow bypass structure (e.g., flow-splitter catch basin) source controls --- Design Information Water Quality design flow ------------- Water Quality treated volume (RAIN GARDEN) 238. 726 AC-FT Water Quality storage volume (wetpool) -------- Facility Summary Sheet Sketch 2009 Surface Water Design Manual 3 1/9/2009 I ,l • 1 ' I i I § I t ' ~ ! jl • • ... 8:. U'JJ -4B" STORM DRAINAGE NOTES: 'l i ~ .s ~"l g,g~<o ~·;/''\ -----,-/PERF P\CfiPE~.~~ RA!H -GARDEN -I ~,r i ~ ------.-·--_._··· -;-,c,C"'~-'c'--,'-c--'-~4~-L---------,_ ---.:....--~·=·..::::--_--.;;;. -~--------r-----. RAIN GARCBl 1.)· - HOOIZ~TAI.. C()llRQ FOR STRUClURES ADJACENT TO CURB IS PROVIDED BY STATI0'4 MY. CONlRACTOO SHALL LAY OUT CURB LINE TO DETERMINE EXACT QFFS[T NECESSARY FOR CUTSIDE Of FRAME TO ALIGN WITH FACE Of a.JRB. HORIZONTAL CONTRct FOR SlRUCTIJRES NOT ADJACENT TO CURB REFERS TO CTNTER Cf" SlRUClURE. '-;! ~J.~ :§ ~~~ ~~~~ 18 ~!~ .r~~ ~ :i~ '/ -~. ~, ___ ~--H r ---+-,--- @O,{RF\_OW STRUClURE RIM 377.00 105TH PLACE SE -. . ~'le ----/~ ----------------------,---------- -I -1 1 , : l I -\, ~: ) ) l~' Ii ,J f_ ' I ~-------. --------, ---, ,,_. ·j ,' . I I ' _·1_ I - P ,, ,.,__.. ------,------,,. ~ L--------;, . ,J ~ ---- UPPER W5EL 38!.~ · ·-"MTTOI· Elli' 3Bcuo REWREO BOTic»J AREA t,141 SF UPPER 'lf.E... 3~9 BOTICJ.1 ElEV 378.69 REQUIRED BOTIOM AR~ 67 Sf ,, 2. TRENCH DRAIN RIM EL£VAT10NS SHO'ftl REFER TO CENTER Cf" TRENCH DRAIN CATCH BASIN. REm TO l;: .,-<o -"'i :§~~ GllAaNG PLAN AND ALIGNMENT PROFllfS FCR REMAINING TRENCH GllA"lt ELEVATIONS :6..J.U"' 0 0.41% n'PE 1 CB -106 STA 41+68.59 RIM 384.07 co 1' IE 376.0 6' POC FOR MEa-1 SUMP 00 PUMP IE 377.0 TRENCH DRAIN -107 Rll,4 384.47 8' IE 382.99 (W) OUT 8' DOIIINSPOOT COillCTOR (DSP) 0 1.IJ% MIN. .fl" !E 382.67 (E) IN 12" IE 382.34 (S} OUT 384 · ·J'es - TYP[1 CB~ STA 4-4+88.42 RIM 385.37 8' JE 38UJ (SE) IN 12' IE 381.00 ;/ / , ;/ ' ' ' '' ,· / -----·-~ ----~ ---.----. --: -----_._·_. --------. ------_/ , , / , Cl) ~ t-I-< z ~ >-;;:: w -1--:!i: ili ii: ::5 t-~ ~ ~ C \_Signatur~sf o~-Gl~ <(!z ~ti w -w / I ~ 10 20 40 1ilch•20fe.t 'SI" -0 C\I CX) t-crc ~;;:: zw-o,:,:: -(/) :ra::: 0 w t~ c..~ zcxc W -'l :::, w 0.. 0 > (.') :c <..:> 0 <( I-Cl 0 I-~ ~ ~ Z ....-~o <( ~ 0 0 "' >~ ~ ct:SIGN DEV. 11/0&'13 COORDINATKW 01/1&14 ~ C\I I I-·---· ol DRAINAGE C/J PLAN I-z = UJ AS NOTED ::!! PLOTc.llTE 01128/14 ::::, -" w.v (,) --AGC 0 "'""' TAO Cl -· I-C6.0 ::!! a: UJ NOT FOR 0.. CONSTRUCTION I WWHM2012 PROJECT REPORT Project Name: R::Lri Gorden Site Name: Site Address: City Report Date: 1/27 /2C:,:; Gage Sea tac Data Start : ~9,8/18/01 Data End 2C09/D9/3C Precip Scale: 1 . C,O Version : 2813/C8123 Low Flow Threshold for POC 1 50 Percen~ of Lhe 2 Year High Flow Threshold for POC l: 50 year PREDEVELOPED LAND USE Name : Basl,1 1 Bypass: No GroundWa ter: 1'" c Pervious Land Use C, Lawn, Flat Pervious Total Impervious Land Use ROADS FLAT Impervious Total Basin Total Element Flows To: Surface Acres . 962 0.962 Acres 1.283 1.283 2.245 Interflow -------------- MITIGATED LAND USE Name : ""'\INGI\RO:':N Bypass: No GroundWater: No Groundwater Pervious Land Use C, Lawnr Flat Pervious Total Impervious Land Use ROADS FLAT Impervious Total Basin Total Element Flows To: Acres .473 0.473 Acres 1.321 1.321 1.794 Surface Interflow Surface INGARDEN -1 Surface INGARDEN -1 Name : RAINGARDEN -1 Bottom Length: 33.79 ft. Bottom Width: 33.79 ft. Material thickness of first layer: 1.5 Material type for first layer: SMMWW Material thickness of second layer: 0 Material type for second layer: Sand Material thickness of third layer: 0 Material type for third layer: GRA'.1EL Underdrain used Underdrain Diameter (ft): 0.5 Orifice Diameter (in): 6 Offset (in): 0 Flow Through Underdrain (ac-ft): 238.726 Total Outflow (ac-ft): 244.167 Percent Through Underdrain: 97. 77 / ") 1 '.?; Discharge Structure Riser Height: 1 ft. Riser Diameter: 24 in. Orifice 1 Diameter: 24 in. Elevation: 1 ft. Element Flows To: Outlet l Outlet 2 RAINGARDEN -l Hydraulic Table Groundwater Stage (ft) Area(ac) Vol\lllle(ac-ft) Discharge(cfs! Infilt~cfs) C.0000 0.0342 0.0000 0.0000 0.0000 0.0275 o. o 341 0.0006 0.0000 0.0000 0.0549 0.0339 0.0011 0.0001 0.0000 0.0824 0.0338 0.0017 0.0001 0.0000 0.1099 0.0336 0.0023 0.0003 0.0000 0.1374 0.0335 0.0029 0.0005 0.0000 r;. : 6 4 8 8. os~.33 0. 8834 O.CJC7 c.oooc 0. :.923 0.8332 0.0040 0.001C C.0000 0. 2198 0.0330 0.0046 0. OOH C.0000 0 . 2 4 ·7 3 0.0329 0.0052 0.0018 C.0000 0. 2747 c,.c321 0.0058 0.0024 o.ccoo C .3022 0.0326 C.0064 Ct.JOJO o.ocoo 0. 3797 C.0324 0.0070 0.0037 0 .11000 0.3571 C.03)3 0.0076 O.DC45 0.0000 0.3846 0.0322 0.0082 C.0051 0.0000 0.C21 0.0320 0.0088 C.CC64 C.0000 0.4396 0. :J31 Y 0.0094 0.0075 0.0000 0.4670 0.0317 0.0101 0.0087 C.0000 0.494.S 0.0316 0.0107 0.0101 0.CJOO 0.5220 0.0314 0.0113 0.0115 O.COOJ 0. 54 9'.J C.0313 O.C'.19 0.0131 J.GCOO 0.'.:,769 C. 03 :._ :._ o.c:26 0.0:47 J. :JCCO 0.6044 0.03:0 0.0;37 0.0:65 J. '.JCCO 0. 63 i9 0.0308 0.0138 0. 018.S o.cc~c 0.6593 0.0307 C.Jl4S C.C205 0.0000 U.6868 0.0305 0. OEl 0. 0227 C.0000 CJ. 71 LJ 3 0.0304 c.::ns7 0. J2',0 C.0000 0. 7418 0.0302 o.,:164 0.·8275 0.0000 0.7692 0.030] Q.C170 0.0301 o.cooo 0. "I 96 7 0.0300 :) . C: ·17 0. 0378 '.J. ocoo 0.3242 0.0298 0.0184 0.03.57 J.0000 0. El 6 0.0297 0.0190 0 0388 0.00CO J. 87 9 j_ o.,J29s (_) . 01 ?-"! C.0420 0.0000 ,J. 9066 0.0294 C.0203 0.0453 0.0000 0.9341 C. o: 92 C.0210 o.orns 0.0000 0.9615 C.0291 0. 021 i O.ClS24 0.0000 C. 98 90 0.0289 0.0224 0.0563 :J . 0000 .016::J 0.8288 o.cno 0.0602 0 . ocoo l.0-~4C 0.0286 0.0237 C.0644 0 . 0000 ~.c7:4 c,. ·:2ss 0.0244 C.0657 0.0080 1.0989 C.C?84 0.:)251 0.0731 C.0000 l. :2 64 0. 028: C. 02 SB O.J778 C.0000 1 . : ::, 3 8 O.C281 ,1. 07 65 0. :JS 26 11.0000 ~. :s ::_3 0. C?7 9 0.C272 0. 08 7 6 o.cuoo l.2C88 C. 0?78 O.C279 0.0927 0. OIJCO 1.2363 C. 027 6 0.0286 0. 0 981 0.0000 : . 2637 C.0275 0. J293 0.1036 0.0000 1.2912 C. 027 4 C.0300 0.1093 0.0000 1.3187 0.02)? C.0307 O.ll52 C.0000 34 62 0. 027' 0.0314 G.1212 0. COC)J ::_. 37 3 6 0.8269 0. 0322 0.:275 0. 02 '.J J 1 . ,: 011 0.0268 Cl. 83/ 9 C.1339 o. oc;:; o 1.i:;2::6 0.0266 0.0336 C.1406 C.J'.Hl-J l.456C: 0.0265 o. 030 0.14/4 C. ODOC ~. 4 8 3:J 0. C2 64 0.0351 c.1s,14 o.oooc :.scco 0. 0 2 62 0.0355 0.1586 o.cooo Surface INGARDEN -1 Hydraulic Table Stag:e (ft) Area(ac) Volwne (ac-ft) Discharge {cfa) To Amended(cfs) Wetted Surface 1.5000 C.0342 0.0355 o.cooo 0.1615 0.0066 1.5275 0.0343 C.0365 0.0000 0.1615 C.0066 l. 5 54 9 0.03,5 0.0374 0.0000 0. :644 0.006b 1. 5824 0.0346 O.C383 0.0080 0. 1673 0.0066 1.6099 0.0348 0.0393 IJ. 0000 1.6374 0.0349 '.J. 04 C 3 O.OGCC l. 664 8 0.035: 2.C4'.l 0.0000 ~. 6923 0.0352 0.0,22 O.OJJ8 1. 7198 0. 0354 0 _ J4 32 0.0000 1.7473 0. 035:J 0.0441 o.cooo 1.'747 0.0357 C. 04 ~ :,_ O.CJOOO l. 8022 0.0358 C. 0461 0.00:JO l. 8 2 97 0.0360 0.0471 0.0000 1.8571 0.0361 0.0481 0.0000 1.8846 0.0363 0.0491 0.0000 l. 9121 C.0364 C.0501 0.0000 1. 9396 C.0366 0.0511 0.0000 l. %70 0.0367 0.0521 c.cooc 1.9945 C.0369 0 .053: o.ooco 2.0220 0.C370 C . cs,; ·1 0.0000 2. 04 95 C.0372 0. 0551 0.0000 2.0769 0.'0?73 o. 0561 o.cocc 2.1044 J.C37'.:; C .057) 0.0000 2.1319 8. (;37'? 0. 0582 o.cooo 2.1593 0.C378 0. 0592 0.0000 2. 18 68 0.03BC 0.0603 c.cocc 2. 214 3 0.0381 0.0613 C.0000 2.2418 0.0383 0.0624 0.0000 2.2692 C.0384 0. 0 634 0.0000 2.2967 0.0386 0.0615 c.ccoo 2.3242 0.0387 0.0655 c.oocc 2.3516 J.0389 0.0666 0.0000 2.3791 0.0390 C.0677 J.COOO 2.4066 C. 0392 0.0688 o.ocoo 2.4341 0.0393 0.0698 c.ccco 2.4615 0. 0395 0.0709 C. C)C,QO 2.4890 0. 0397 C . 0720 O.JJCO 2.5000 0. 0397 C.0"124 1.9235 Name ' Surface IN~_;...RJE::; Element Flows To: Outlet 1 Outlet 2 RAI t'1:;P1.RJSN 1 ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.962 Total Impervious Area:1.283 0.1707 0.0066 0.1731 0.00f6 CJ. J 7 E 0 ~.C066 0.1789 C.C066 0.1818 :::·. C066 0.18-17 Q_·J066 0.1876 ~LJ066 0.19CS 0.0066 0.1934 0.0066 0. 1963 0.0066 0.1992 0.0066 0.2021 0.0066 C.2050 0.0066 0.2080 0.0066 0.2109 0.0066 0.2138 0.C066 C.216"7 0.0066 C,.2196 0.0066 J.2225 0.0066 0.2254 C.0066 0. ?283 0.0066 0.2312 0.0066 0.2341 0.0066 0.237C C.0066 0.2399 0.0066 0.2,26 O.OOG6 0.2457 0.0066 0.2486 0.0066 0.2515 C.OOGG 0.2'J44 0.0066 0.2573 O.OC66 0.?.602 0. 0066 0.2631 C . Oll66 C. 260 C .OOCO Mitigated Landuse Totals for POC #1 Total Pervious Area:0.473 Total Impervious Area:l.321 Flow Frequency Return Return Period Periods for Flow(cfs) 0.318262 0.412232 0.47"/324 0.56305 0.629543 0.698366 Predeveloped. POC #1 2 year 5 year 10 year 25 year 50 year 100 year Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.320013 5 year 10 year 25 year 50 year 100 year U. 565547 0.756757 l.C27439 1.24855 1.485217 Stream Annual Year Protection Duration : 94 9 1950 : 0 '.): ::. 9S2 1953 19S~ 1.955 19:;E J 95 7 1958 195 9 1960 : 96 '. 1962 1?63 ·. 964 ~-9 6 :") 1966 1967 1968 1969 197 8 1972 1973 197 4 1975 1976 1971 197 8 Peaks for Predevelopad and Mitigated. Predeveloped Mitigated 0.07 0.379 O.H9 0.483 0.272 0. 4 64 0.2]5 0.122 :j. 2 33 0. 210 '.J. ;:· 59 0.:20 C.288 0.424 C.285 0. 377 0.339 0.582 D. 25-7 C. 30 6 0.248 C. 222 C.282 0. 182 0.285 0.180 0.233 0.121 C.276 0.121 C .257 0.195 C. :353 a. 22E 0 . 222 0.121 0 .39: 0. 64 8 0. 441 0.250 0.321 0.387 0. 297 0.288 0. 3So J. 241 0.399 0.619 C.204 0.232 0.332 0.12] 0.342 0.582 0.257 0.167 0.250 0 .121 0. 314 C.557 POC #1 : 97 9 1980 1981 1982 1983 1984 : 985 1986 '987 \988 l98Cj ;990 1991 1992 1993 1994 ~ 99~. 1996 i 997 1998 1999 200C ,oo: 2002 2003 2004 2CCS 2006 2C '.":7 2:88 0 -I,/. I} 0. 4 5 3 0.329 0.481 C.36o 0.240 0.330 0. 276 0.421 0.248 0. 310 0 _ 6' l 0.510 0.238 o.:99 0.207 0.289 0.336 0.319 0. 29'7 0.660 0.318 0.326 0. 431 C.335 C. 612 0.281 J. 2 51J C1. ::J99 0. sco 0.380 Stream Protection Duration 0 .123 0. 197 0.338 0.829 0.5:6 0.178 0.308 0.473 o.so: 0 .121 0.121 1. 106 0.852 C.378 0.120 C.120 0.370 C.504 (). 192 J.280 J. 8 9 .j J.434 8. 121 0.723 0. 1 21 l.J55 0. 479 0.345 0. 995 0. 82 9 0. 564 Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.67C7 1.1062 2 C.6602 1.0547 3 L 6 7 8 9 :o : 1 ·c2 :3 1 4 15 16 17 18 19 20 21 C.6118 0.5994 0.5098 0.500'1 0.4809 0. 4 533 0.4Ll 0.4367 0.4305 0.1242 0.4210 C.4190 0.3992 0.3910 0.3796 0.3654 0.3551 0.3535 0.3424 C.995C 0.8937 0. 852./, 0.829S 0.8294 0. 7276 0.6478 0.6192 0.5818 0. :)818 0.5641 0.5521 C. 516'± C. 0044 C.5010 C. 4 965 0.4832 0.4820 0.4789 22 c. 3392 J. 4 7 32 23 C . 33 6:) 0.4639 24 0. ::'! 3,; "/ 0.1335 25 C. 3321 0.4235 26 0. 33CO 0.3920 2 l 0.3288 U. :JB/3 7e 0.3)56 0.3787 29 0. 32L 0.3778 30 0.3]88 0.3765 31 0.3183 0.3701 32 0.3137 0.3445 33 0.3099 C.3384 34 0.2974 C.3076 3o 0.2971 C.3059 36 0.2891 C.2879 37 0.288] 0.2801 38 C.2851 0.2499 39 C.7RSJ 0.2413 40 0.28:8 0.2325 41 C.28:1 0.2255 4? 0.2761 0.2224 13 0.2756 0.2097 44 0.2716 0.:.. 91, 6 45 0.2594 0.1800 ~6 0. 2 '.! '/ 4 0 .178:l ,~ 7 C.2572 0. 167 3 48 0. 2 ~) f.7 0.1230 49 0.2537 0.1218 :;C 2.2498 C.1215 51 : . 2 4 t3 3 C. ~?J4 52 ::.2478 C.'21.3 53 C.2101 0. :212 54 '.:. 2 3 7 9 0. 1-2 :2 5~ C. 232 I 0.1210 56 :.2325 0.1207 57 ~.22:6 '.J. l2C 7 '."18 : . 2 ::_51 Cl.12CS 59 D.2C67 0. 12C2 60 0.203.S 0.1202 6: 0.1986 0.1200 Stream. Protection Duration POC #1 ciu:c::atior. st.andard for l+ flous. Flow(cfs) O.l59:".. 0. 163 3 0. 163 6 0.: "34 0.1781 0.1829 0.187E 0.1924 0.1971 Predev :G79 1S38 :369 1218 1095 10l3 934 832 748 Mit Percentage Pass/Fail 1536 91 ?ass 1496 97 ?ass 1124 l04 -.'c,; I 1388 ::3 ~acl 1318 ::.20 t•,-,j l 1280 i76 ,.,, 1219 1180 lHC 130 Ul 152 :·-·_ l F·~, ---- 0. 2:i; 9 7 C) 4 ll08 157 ",-, I 0. 2066 6SQ 10 61 163 ~·a' l 0. 2114 588 1_018 173 ,. ,c)__:_ l 0. 2162 54/ 98 6 :so F.: 0.2209 5;4 94~ :_53 0.225·7 -J 68 90 6 193 0.2304 426 8 63 207 .-_ -~-.l C. 2352 395 8 34 2:1 ,. •' • 1 0.2399 372 805 2:6 2. -~ 0.2447 356 775 2;7 fc,~: 0.2494 327 743 227 /"' .J 0.2542 30~ 7ll 236 -~~- 0.2589 283 682 240 . ·-• l :.2631 263 657 249 C·.2684 20 622 255 f D.2732 224 598 266 0.2779 209 S74 274 :J. 2827 197 546 277 ~, _;_ -'- 0.2874 185 ~27 284 -•.• j 0. 2922 171 495 289 f _ _._ ~ 0.2969 161 430 2 98 f ' 0.301'/ 152 4 61 303 0. 3C 64 141 437 3J9 0.3L2 ;:L 11 7 318 n " . 3J. '.J9 125 4C9 10n -' , 0. '.)2C) ;;4 382 335 C. 32 5.j :os 3 6:', 337 . '--- 0. 3302 102 3:;.2 345 0.3349 99 344 34 7 ~ .J ~ _j 0.3397 92 ro L, 357 ' ., --· 0. 34 4 ~ 84 317 377 Q. 3492 g 1 2 97 366 0. 3539 79 286 362 f . ' C.1527 "E / 'J ~ ::s 6 C. 363:-i 76 2 62 34 'i C.3687 ·; C 216 3Sl 0.373:: 66 238 ::360 C ~ o. 31 n 63 229 363 0.3825 60 220 .3 6 6 0.3872 57 209 366 f"::. -- 0.392J 55 201 365 C.3967 51 193 ~'J 8 -', 0. 4C1S 48 18 E ~'.'. 7 0. 4C 62 4S :SJ 4 ::)2 0. 4,;o {3 :76 1J J 9 " v. 41 ~' 7 39 : 69 13] 0. 420S 37 ; 64 4 4 3 C . 4 252 32 ; 62 50 6 0. 4300 31 ·1 fiO 516 0. 4347 30 153 ', 1 J 7 ·, 0. 4395 27 14 8 548 ., Cl 0. 4442 25 IH 576 : ,j 1 0. 4 4 90 23 1.39 604 r c 0. 4 537 22 137 622 0.458S 21 129 6>'; 0.4632 20 126 630 /::;.· C.4680 19 122 642 :-0.:_1 0. S 727 0. i; i 5 0. i; 8 22 0. i; 6 7 J C. i; (): ~' C. 4 960 0. SC J. 2 C .. S06.J 0. :. :.c 2 C. 5: '.:: 5. c.:2c3 c.:2so o.~2ss ~.S.~4S J.S393 :•.S44C :1.5488 :.1. '.)53:J CJ. 5583 C•.5630 0.'.)E78 0. '.) 7)5 C.5773 C.'i820 0.5868 C.59:5 C .c%3 C.60:0 C.6058 o. 61 c::; 0.6153 0.6:100 0.6248 :).629'.) 17 1 i 13 13 12 12 lO 9 8 8 8 8 8 8 7 7 7 7 7 7 6 5 5 ~ 1, 4 3 2 2 2 2 ::s ::s :os ; 04 ,O? 101 96 9:-._ 88 86 84 83 BC 79 77 73 7 1 68 67 67 6 ', 63 61 ::,8 S7 53 53 52 ~) ] Sl 48 ES4 076 830 800 8SO e41 960 1 J 11 liOO 1.':J75 1J50 l:; 37 : JC: 0 9.37 : :;_ C) 0 '04 2 1014 9'/ 1 957 957 928 900 87" 966 1140 J l 00 j 1 co J 3 7 .S 1325 J 7(,6 26CC 2 '.)50 2 ~.so 240C r ,.J ; ;_:i_ .:-':; _ • .-_ _. ..!. t·:- Fa 1';,.2_j_ h": !·?.. l The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or mare than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Water Quality BMP Flow and Volume for POC #1 On-line facility volume: C acre-feet On-line facility target flow: C cfs. Adjusted for 15 min: 8 cfs. Off-line facility target flow: 0 cfs. AdJusted for 15 min: 0 cfs. Ferlnd and Implnd Changes No c~a~~cs have bee~ m~de. This program and accon-.pan~·ing dccumentation are pro•.-ided 'as-is' without \1at:"rant:: of an:,· kind. ':'he entire risi-:. regarding ~!le ;:ierforrnance and results c: this program ::_s assumed b;· End User. Clear Creek Solutions Inc. and the go·:ernrr.ental licensee or sub:icensees disclaim all 11ar.rantics, eit!"lcr expressed or ir'.'.µl i ed, :nclud:;_c1g bt.:t not l ir.,.:ted to i::ir.L.1ed ··at:"rant.1es o: prog:::arr. and ac.cc:n~ar.yi11g docurr.er.tatio:1. Iri n.--i e··e:-it sha.:..l Clear Cree:-· Soll;tions l:ic. be l1able for an:,· damages ·,botsoe.,er {inclt.:d.'..ng 1,1ithout .:.. i1~.: ta, . .10'."l to damages for l::s~ of LJusj_r.ess prcfits, loss of business inf·:Hmaticn, busir:ess i:-1tcrrupt1or;, a;1d the .:..1;.;e: aris::.ng out of the use ot, or inabi:..i:..~· to use t'::s program even if C~ear C:::eek Solutions Inc:. or '.:heir authorized representat::_··es ha·:e beer: dd.,·isec!. of the possib.11::..ty of sue:, damages. Software Cop1:::1ght Oby Clear Creek S0lut:o:1s, Tn(":. 2C05-20l3; All Rights Reserved. KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL Water Quality: RAIN GARDEN -2 Type/Number of water quality facilities/BMPs: biofiltration swale large) --- (regular/wet/ or continuous inflow) large) ___ combined detention/wetpond ___ sand filter (basic or large) ___ sand filter, linear (basic or ___ sand filter vault (basic or (wetpond portion basic or large) combined detention/wetvault sand bed depth ___ (inches) above --- ___ filter strip ___ flow dispersion ---farm management plan ___ landscape management plan ___ oil/water separator (baffie or coalescing plate) Liner? --------- catch basin inserts: --- Manufacturer stormwater wetland --- storm filter --- ___ wetpond (basic or large) wetvault --- ___ Is facility Lined? If so, what marker is used X RAIN GARDEN -------------------- ___ pre-settling pond ___ pre-settling structure: Manufacturer ------------------- ___ high flow bypass structure (e.g., flow-splitter catch basin) source controls --- Design Information Water Quality design flow ------------- Water Quality treated volume (RAIN GARDEN) 15.151 AC-FT Water Quality storage volume (wetpool) _______ _ Facility Summary Sheet Sketch 2009 Surface Water Design Manual 3 1/9/2009 • • • ~ ; § f I i ~ i i Si ~ ! • ' • ",q; IJ!1 ? -4§ '. STA 21+36.26, ·!6.+7' RT. RIM 382.~1 6" & a· 1E 376.39 (E} IN --.. ---------p)'----_ , ' ·12" IE 3~39--·- ... ,.-.... <."_.--.1 .• :·. "'.,: •. ·,_ -•• '. ' ----------· --~-~---~-·-~--~~--·~ @ O\£RFI.OW SlRUClURE Rll,I 377.00 ,J, l 105TH PLACE SE .. IrFf I C8 802 . RAIN GA.ROEN ~ _2- ~-. 41-~· . .iir' \ UPPER WSEL 37'!r.6g 20-+00 lRENCH DRAIN -10C() RIM JB0.56 8' IE 378.98 BOTTCH ELEV J78.69 REQJIRED BOTT()! ARE}, 67 SF -----------( -------- I I '. ·\ // I I 'l ' ,. '1 r ') I "fl I' ,.I I .·-- i-i -~ "' --------- ~ <:-.- 0 0.41% T'l'PE 1 CB -106 STA 41+68.59 RIM J84.07 CO TG IE 376.0 6" POC FOR WECH SUMP AND PUMP IE 377.0 lREtlCH DRAIN -107 Rlt.l 384.47 s· 1E 382.99 (wJ cm B" DO'llt!SPOUT Cll.LECTOR (DSP) 0 1.0,: MIN. 8" IE 382.67 (E) IN 12" IE J82.34 (S} OOT ·/'~ ,,,,,.: /)' -----,-. -. -,s· PERI' P~ t·1P£ ~ ~_j, RAIN i>ARDEN -1 "k/ ~ UPPfR WSEl 381.40 . -'BOTTI::M EIIV ~-40 RECIUIRED BOTTct.l AREA 1.141 9'" ;._,, Qfil_ STORM DRAINAGE NOTES: HOOIZllHAL C(),ITRQ F~ STRUCTIJRES ADJACENT TO CURB IS PROVIDED BY STATICtJ ONLY CCtflRACTOR SHALL LAY cm CURB LINE TO DE1ERMNE EXACT OfFSET NECESSARY FOR DU151DE Cf FRAME TO AU<ll 'MTH FACE OF aJRB. HORIZONTAL C()flROL FOR S1RUCTIJRES NOT ADJACENT TO CURB REFERS TO CENTER Cf STRUCl\JRE. TRENCH DRAIN RIM ELIVA110NS SH~ REFER TO CENTER Cf TRENCH DRAIN CATCH BASIN. REFER TO GRADING Pl.AN AND ALIGNMENT PROFllfS FOR REMAINING TRENCH GRATE ELIVATIONS. ·yas · TW[1~~ STA 4-4+88.42 RIW 385.37 JB 8" IE 361.33 (SE) lN ---4 -----im1.oo / / I / , I / I / I I I ,, ,I ~· . . . ~ ----.:.--~ ~ .,.--·--~--'------__ ·_._ ----------------_ __/~ I __ L -~.----! ' ---~ --~ -.... { ~ J------t""-~ ,0 20 ~ . ~ t ~ .s; "'"" g,g~<o 'IJ <c, I <ti' .,.,-._,:;::, ..% ~~~ ] ~~& Iii~!~ ~]~ ~j~ c.:::~~ ~~i -V)~ U) z 1--~ C: \_Signatur m ~ ~~ ::::1: vi i:2 ::s 1--< o- ~:,: I~ sct'O~-Gl~ ., ~I (\J cb (\J <( >-C) >-' z z en 1--UJ ci5 UJ a:: ::, :,: Z w 0"" -(/'J ::i:::O::: 0 UJ >-<( c.. u ._a. w ::s §§ ffi C, a. 0 > <( f': ug I-~ ~ z z --<( <( -""0 O 0 > ~ (Cl --DESIGN DEV. 11/0al13 COORDINATIOO 0111!>114 ~ i; I DRAINAGE PLAN (/) I-m SCAJ.1: ASNOTED ~ P,.l)Tl)lfE 01/28114 ::::, ~ tMV (.) PRCJ.MGA.. AGC Q 1,W'TER: __ ___ _ TAO Cl I-C6.0 ::iE a: UJ NOT FOR 1flch•20feel 0.. CONSTRUCTION WWHM2012 PROJECT REPORT ProJ ect Name: S!v'.A:..,:_, ?C: Site Name: Site Address: City Report Date: 1/27120·: 4 Gage Sea tac Data Start , 1948/:01:: Data End: 2009/J9/JO Precip Scale: ~ . .J :J Version 2C13/02/23 Low Flow Threshold for POC 1 : 50 Fercent ot the 2 Yea.:- High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basi:1 :;_ Bypass: No GroundWater: Ne, Pervious Land Use C, Lawn, Flat Pervious Total Impervious Land Use ROADS FLAT Impervious Total Basin Total Element Flows To: Acres .962 0.962 Acres 1.283 1.283 2.245 Surface Interflow MITIGATED LAND USE Name : RA.:~GA~DEN 3ASTNr Bypass: No GroundWater: Ko Groundwater Pervious Land Use C, Lawn, Flat Pervious Total Impervious Land Use ROADS FLAT Impervious Total Basin Total Element Flows To: Acres .079 0.079 Acres 0.058 0.058 0.13? Surface Interflow Surface SMALL RG Groundwater Surface SMALL RG Name : SHALL RG Bottom Length: 8.23 ft. Bottom Width: 8.23 ft. Material thickness of first layer: 1.5 Material type for first layer: SMMWW Material thickness of second layer: 0 Material type for second layer: Sand Material thickness of third layer: 0 Material type for third layer: GRAVEL Underdrain used Underdrain Diameter (ft): 0.5 Orifice Diameter (in): 6 Offset (in) : 0 Flow Through Underdrain (ac-ft): 15.151 Total Outflow (ac-ft): 15.244 Percent Through Underdrain: 99. 39 7 "ti'% ,,.- Discharge Structure Riser Height: 1 ft. Riser Diameter: 24 i~. Orifice 1 Diameter: 24 in. Elevation: 1 ft. Element Flows To: Outlet 1 Outlet 2 SMALL RG Hydraulic Table Stage (ft) Area (ac) VolUille(ac-ft) Discharge(cfsl Infilt(cfs) 0.0000 0.0037 0.0000 0.0000 0.0000 0. 027 5 0.0036 0.0000 0.0000 0.0000 0.0549 0.0036 0.0001 0.0000 0.0000 0.0824 0.0035 0.0001 0.0000 0.0000 0.1099 0.0035 0.0001 0.0000 0.0000 0.1374 0.0035 0.0002 0.0000 0.0000 ,.) . : (4 t: J.1S?3 =:1 .2198 J. 2.:; ·., 3 0 . /. 7 t, i 0.3022 0. 32 97 0.3571 0.3846 C. 41-2 l C.4396 0.467C 0.494) 8. 52?.U 0.5495 0.5769 0.6844 0.6]:9 J.6593 8. 68 68 0.7l43 iJ. 7 418 C.!692 0.7967 C. 824/. C. 851E C. 2 7 9:.. C.9066 0. 934: 0.96:S C. 98 90 : . o:;. 6s " . 0 4 4 0 . 8959 1.:26, . '.. 538 :.:s:J . ;'r,88 . )] 6.'< ; . 2637 1.29:2 l. ]1 ~· '/ J . 34 6:'2 :.3736 :.,:_: 1.4286 1. 4 :l 6C 1.1~L~.S l. 5000 C.CC34 0.0034 C.0033 C.0033 0.0033 C.0032 0.0032 0.003: 0.003: 0.0C3C 0.0030 0.0030 0.0029 0.0079 0. 002 9 C.0028 0.00)8 O.C027 0.0027 D.CJ0/.7 0.0026 0.0026 O.OO?S 0.002~ 0.0025 O.J·J24 C.JJ24 '.). C 0/ ~ '.).CD23 J.CC23 O.CC22 0.0C22 u. :;o;,i~ C.0021 C.0021 C.OC?l C.0020 0.C02J 0.0019 O.OC19 C.0Cl9 0.0018 0.D0~8 C.0018 C.0017 0. GOl "I '.J. JO :--i o. :rn-i 6 o.oc:6 0.00;.6 0.0002 C.OOJJ C.0003 0.0003 0.0004 0.0004 o.coos 0.0005 0.0005 Cl. O:JC)6 0. Cl:J'.J6 O.OOC7 0.000"! 0.0008 C. OJ'.JS : . 800 9 (;. ::,00 9 0.GOlO ·~.CClC o.cc:1 o.cc:1 0. oc :.2 0.0012 0.0013 C.0014 C.0014 c.u.~ns 0.0015 0.0016 8.0017 O.C017 0.0018 o.oc·a 0.0J:9 0.0020 C.0021 . .., . 002.2 8.0022 0. 0023 0.0024 0.0025 0.0825 0. JCJ2 6 0. O'.J27 C. 0077 U.0028 0.0029 0.C030 0.0030 C,. O'JOJ o.oo:n C:. 0001 C.0001 0.0001 0.0002 0.0002 0.0003 C.C003 0.00C4 O.OOC4 0.0000 0.0006 0.0007 0.0008 0.0009 0.0010 0.0011 0. 00::.2 C.CC'.,.3 0. oc:o 0. 801. 6 0.0018 0. DO J. 9 8.0021 0.0023 C.0075 0. 0()27 0.002'9 0. OJ:?, 1 C. J;::3.3 O.CC36 O.OC38 O.JC41 0. :J0 113 O.C:849 0.0052 O.CCJSS C.C058 C:. C061 C.C065 C.0068 0.0012 C.007E C.0079 0.0083 0.0087 0.0092 0.0094 Surface SMALL RG Hydraulic Table C. 0'.)8C 0.0800 o.oooc o.oooc o.oooc C.OOOD C. 00,JJ O.OOJO Cl. CJ~)O :J' ::c :::,o J.CCCO ~.::coo o.ccco O.OCCO O.JCCC o.cooc o.oooc C. O:!JC C.0000 C.0000 0.0000 0.0000 0.0000 o.ccoo o.cooo G.OOCO o.ooco 0.0000 0.080C 0.0000 C.0000 0.0000 0.0000 0.0000 O.COGO 0. coco 0. ooco 0.0JCO 0.0000 C.OJOC 0.0000 0.0000 0.0000 o.coco C.OC~<J 0. :JO~; '.J 0. :J~Jl}'.":· 0. JOO'.; C. OJJC 0.0000 Stage(ft} Area(ac) Volwne(ac-ft) Discharge(cfs) To Amended(cfs) Wetted Surface l.SCOO 0.0037 U.JJ30 0.0000 O.C096 0.0004 1.5275 1.5519 1.5824 0.0037 O.JC37 0.003C C.JJ31 U. ']032 0.0033 0.0000 0.0000 0.0000 O.OC?6 0.0098 C.2099 C.0004 0.0004 0.0004 : . 6C99 :.637e 1. 664 e 1. 6923 :.7198 l. 1473 J . 774-. 7 l. 8022 1.8297 1. 8571 1.8846 l. 9121 1.9396 1. 9 67 0 1. 994 5 7.0220 7.0495 2.0769 2. 10;, .; 2.1319 2. 1593 2.1868 ?.2143 ? _ 2,:; 18 2.2692 2.2967 2.3242 2.3516 2.3791 2.4066 2.4341 2.4E15 2.4890 2.:cco 0.0036 0.0Cl39 0.0039 C.OC39 C.0040 0.0040 0. O:J4: 0.004: 0.0042 C.0042 0.0043 0.0043 C.0043 C.0044 0.0044 C.0045 C,.004~ Ci. 0846 0.0046 O.C047 O.CC47 1.co4·; J.·JJ48 J.JJ48 O.J0~9 O.CC,49 0.0058 0.0050 O.OO~il 0.0051 0.0052 C.0052 0.00',3 O.OD53 ·:.C034 '.}. CJ3:-J O.C036 0.0038 0.0039 0.0:40 D.JC41 0.0C42 0.CJ43 0.0044 0.0045 0. 004 "/ 0.0048 O.CC49 0.0050 0.0051 0.0053 0.0051 0.0055 0.0056 0.·'.)058 0.0059 0.0060 0.0062 0.0063 0.0064 0. 0066 0.0067 O.OC68 0.0070 C. OOF:,. O.OJ"l3 0.0074 o.oc-1:; Name : Su.r:'ace Sll.l;_L:_, RG Element Flows To: Outlet 1 SMALL RG Outlet 2 ~l. 800C c.cccc O.OOQO O.OOJJ :J. O:JOO :.) . oooc 0.CUOO 0.0000 0.0000 0.0000 0.0000 c.occc 0.0000 0.0000 O.OJOO 0.0000 c.cccc 0.0000 0.0000 0.0000 o.ooco C.OCOO C.0000 C.0000 C.0000 G. OOCO c.occc Ci.DODO 0.0000 0.0000 0.0000 8.CUCO 0.CCDO . 9S 3:) ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.962 Total Impervious Area:1.283 c.0:01 0.0103 0 0104 U.0106 o.c:os 0. 0 :._10 0. o:.::.::.. 0.0::3 O.OllS o.o::6 0.0:18 0.0120 0.0122 0.0123 0.0125 C. D :._77 0.0129 ·J.0130 J.Cl32 C. C 13/J 0.0135 O.Jl37 O.Jl39 0. 0 J 4' 0. Cl42 C. C-144 o .. Jl46 0.Jl47 0.0149 8. 0 ls:.. 0.0153 0.0154 0.0156 0.0157 . GOO 1.i .C004 . 8004 :J. r~CCLJ :J.D0C4 0. '.)GC4 0.0004 0.00C4 C.0004 0.0:)04 0.00J4 0.0004 0.0004 C.0004 0.0004 0.0004 0.00C4 C.0004 0.0004 0.0004 0.0004 0.COC4 0.000~ 0. 0001, 0.0004 0.00~.j 0.0004 0.CCC4 IJ.0004 0.0004 0.0004 0.0COe o.cooo Mitigated Landuse Totals for POC #1 Total Pervious Area:0.079 Total Impervious Area:0.058 Flow Frequency Return Return Period Periods for Flow (cfs) 0.318262 0. L2232 0.17 7 324 0. 5630'.J 0.629::;.;_;3 0.698366 Predeveloped. POC #1 2 year 5 year 10 year 25 year 50 year 100 year Flow Frequency Return Return Period Periods for Mitigated. Flow (cfs) 2 year C.010175 5 year C.017991 10 year C.025318 25 year 0.037'723 50 year D.C49i61 100 year 0.064637 Stream Annual Year 194 9 1 Q !:. ~, 19: ~ J. 9'.;2 1 ~ '.:.: 6 1?57 J SS8 1959 ::_ 960 J 9 G; l 962 :_953 l 96, ~ 96~ ~ 966 ~ 967 1968 ~969 : 970 1 '}"/ l :97.'.::'. : 37 3 1 g-,, l, 197 5 197 6 1977 1978 Protection Duration Peaks for Predeveloped and Mitigated. Predeveloped Mitigated o.,37 a.COB O.c:9 O.COS 0.272 0.019 C.2_S 0. 233 ::i -;75 9 0.288 c:. 2 3c 0.339 U. ';' ~ 7 0.282 C.785 C.233 C. 276 C.257 0. 3'.:d 8.2/2 0. 39: 0.441 0.321 0.)97 0.355 0.399 0.?.84 0.332 0.342 0.257 0.250 0.314 0.008 0.008 0.088 C. C' 4 C.008 C.008 0.008 0.008 0.029 '.!. 008 O.CC7 0.008 O.CC8 O.U08 0.008 0.008 0.008 0.008 0.008 C.008 C.01/ C. OJ2 0.008 O.OCB 0.008 0.008 0.COB POC #1 POC #1 .c 9; 9 ~980 J 9 81 1982 1983 1984 1985 198 6 : 98'/ 1988 1959 1990 1991 1992 1993 1994 :. 995 1996 1997 J_ ·~98 1S99 2COO 2C01 2C02 2'.::03 2DO~ 20:}S 2 JJ6 2001 20~)8 ;::c:o 9 o. 42 1} 0. 4S3 0. 329 0 .48' C .365 0.240 0.330 0.276 0. 4 21 0.248 o.:no 0. 67: 0.510 0.238 0.199 0. 287 0.289 ,J.336 J.319 C. '2 97 C.660 C.3:8 Ci.326 0. 4 31 0.335 Cl.612 0.281 G.?:: 4 C. 'i 'l9 C. SO·:= C.32J Stream Protection Duration 0.008 :) . 088 0.008 C.048 0.008 C.008 C.008 0.027 0.025 C.008 C.008 C.047 C. 03t,; C.008 J.CJB 0. COE o. :cs 0. 836 0 :,? .3 C. J'.::8 0.0:9 0. Q,]8 0. 085 0. 023 0.008 O.CSl C.008 0.008 0.037 0. 053 0.817 Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.6707 0.05)8 2 O.E6C2 0.05:3 3 0.6il8 0.04"9 ,1 5 6 7 8 9 :o 12 13 14 15 16 l7 18 i9 20 21 0. 5994 0. 5098 C .5004 C.4809 0.4533 0.4411 0.4367 D. 4305 0.4242 8 .4210 0. 4 1 9 CJ 0. 3 992 C. 3910 C. 37 96 0.365fJ C.3551 C·. 3535 0.3424 0. 046S 0. 0366 0.0357 0.0337 O.C287 C . enc 0. 0253 C. 02 35 o. 0726 0. 0194 C.0192 C.0168 C.0167 8.0142 0. OCP o.ccn O.CC77 0. 0077 «:L C.3392 U. 33(:~ 24 C.3341 ?5 C. 3321 ?6 C. 330J 27 C.3223 28 0.3256 29 0. 32 :Cl 30 0.318E 3l 0.3183 32 J.~137 33 '.). 3099 31) 'J.2974 35 C.2971 36 G.2891 37 G.7881 38 C.2851 39 C.28Sl 4G C. 2318 41 C.2811 4 .'2 0.276:i I, 3 J.2756 'J{ 8.27:.6 1,.:;. 0.7591, 46 0.2574 4 0.2572 48 0.2567 i:; g 0.25J7 50 C. 2 lj 98 '-) ! 0 . 2,:; 8 3 '.)2 0. 2 4 ·7 8 q a~ :J. )!, 0 J S4 0.2379 ::: .) 0.2327 '.:6 0.2325 57 0. 22l 6 :8 11.2151 59 C.2067 EO n. ~ c-,---,' -.,J • '. ~· .) :J Gl 0 : ~s 6 ,.1. Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. 0. 00 1·· 0.00/7 o. oo:-.i 0. OCT/ C.0077 0.0011 0.00,7 O.CC77 o.ccn 0.0077 0.0077 CJ. 0877 0.'J'J77 0.0077 Cl. 0'.11 fi 0.0076 C.0076 C. 0 07 6 c.c,015 :.C076 C.C076 J. C C'i 6 C.C076 C.OC76 0.0076 O.OC76 0.0076 O.OO"i6 0.0076 0.0016 u. oo·.i 6 C.0006 o.oo,G 0.0016 0.0076 0.0076 0.0076 0.0076 0. 0071, 0.0063 Flow (cfs) Predev Mit Percentage Pass/Fail 0. : c 9 ·. : fi ·; g 0 0 Pass o.:639 1538 0 0 Pass C.1686 1369 0 0 ?ass 0.1734 12:8 0 0 Pass 0.: i 81 1095 0 0 Pass 0.1829 1c:3 0 0 Pass 0.1576 931 0 0 Pass 0. 192 4 832 C 0 Fass 0. 197 i 748 C 0 Pass 0.7019 704 C 0 Fass 0.2066 65C 0 0 Pass C .211~ 588 0 C Pass 0. 2:62 50 '.) ?ass 0. 2209 S 1. 4 C ) Pass 0. 22S7 4 68 0 ) hiss 0.230~ 426 0 " Pass v 0.2352 395 0 ,. Pass C.2399 372 0 0 Pass 0.244"/ 35 6 0 0 ?ass 0.2494 327 0 0 Pass 0.2542 301 C 0 iass 0.2589 283 0 0 Fass o. 20r 2 '""::! C-0 0 Fass 0.2684 24J 0 C ?ass 0.2732 224 0 0 Pass 0. 2'7'79 209 0 0 Pass 0. 2827 197 0 0 Pass 0.2874 185 0 0 Pass 0.2927 171 0 0 Pass 0. 2 969 16: 0 0 ?ass C.3C:7 "Cc ~"" 0 0 Pass C.3064 10 I) 0 Pass C.3112 131 C 0 Pass 0.3159 12'.) C 0 Pass J.32J7 ll~ 0 0 Pa::::s 0 .3254 lCB 0 0 Pass 0.13C2 :.02 0 0 Pass C.3319 'J9 0 0 Pa.':3S C.3397 92 C I) Pas.s C. 3-l ~ 4 54 0 C Pass (J.3~92 8'. 0 0 Pass 0.3539 79 71 0 c'ass 0.3587 75 0 0 Pass 0.3635 76 0 0 Pass C.3682 70 0 J Pass 0.3'J::lQ 66 C C Pass V 0 _ 3 7F7 63 0 n Pa.ss V C.3825 60 0 C Pass 0.3872 r..:,--; 0 0 Pass 0. 392C ss 0 C Pass 0.3967 ~: 0 '" Pa::;s C. l C' c 48 C ., Pass V 0. 4 0 G2 45 0 8 Pass CJ. 411 ~ 43 0 C ?ass J. 41 ~-, 3~ 0 c, ?ass 0.4205 37 n 0 Pass V 0.4252 12 ,J 0 Pass C.430C 3~ 0 0 Pass 0. 4 34 7 30 C 0 Pass 0.~39S 27 C 0 Fass 0 _ 4 -c! ~L 25 0 0 Pass 0. 4 ,] 90 23 0 0 ?ass 0.4537 22 0 0 ?ass 0.4585 21 0 0 ?ass 0.4632 2C 0 0 Pass D.1,6~J 19 0 C ::·ass 0. l I 2'7 l 7 0 C Pass 0.477S j 7 C C :::·ass c.,1~::::2 13 G C :'ass C.42 /:} :3 0 A :?ass v 0.4'LI j 7. 0 II ~· a. s s 0.4065 12 0 0 ~~ass 0. :~ C 12 j_Q 0 J Pass 0. :: C: 60 9 (! :1 Pass C.5'.C8 8 0 0 Pass C. ~: 1:::: 8 0 0 Pass C. c2C:J 8 0 0 Pass C . ::2so 8 II J Puss . '.;298 8 J 0 i=:ass () . :; 3 4 '.J 8 J 0 !?ass 0. :J3 93 C Pass 0. 5/J iJ 0 J V Pass r:,. S48R 7 C 0 Pass Ci. 553~) 7 C 0 Pass 0.5583 0 0 Pass o.~n3n ·; C J Pass C.5678 7 C 0 Pass C.5725 7 C 0 Pass C.'>773 C 0 Pass o. s2 ;:,o 6 C () Pass 0 .. S868 5 0 Pass 0. 5 9:__ 5 5 u 0 Pd.s::; 0. :J963 5 ,, 0 ?ass V 0. 60::. C 4 C 0 ?ass () . o::::A3 ' :; 0 ?ass C. s·cc :i ., () ?ass c. 6:53 / 0 0 Pass C. 62CC 2 0 C Pass C. 6)4 t: 2 0 ,; Pass c. 6:095 0 C Pass -------- Water Quality BMP Flow and Volwne for POC #1 O:i-L:.ne facility volume; 0 acre-feet 0.i-11.ne facility target flow: G cfs. Adjusted for 15 min: C cfs. Off-line facility target flow: J cfs. AdJUSted for 15 min: C cfs. Perlnd and Implnd Changes KJ c:anges have been rr.ade. Tins pr0grc.:n and a::::cor:.pan"inq documentation Jl'.'e p:co·.·1ded 'as 1s' Wlt:°JcL:t 11arrant./ of ar:~· k.:.nd. The entire r.:..s:.: rega.:cing the ps~:orrr.ancc and rcsi.:.lt~ of th.:..s proyro.r:. is assumed b~· :C:nd l..'ser. C~12ar Creek so:..uticns lr.c. ar.ci the go""e.:n~er,tal licer.see or sublicer,sees d::.sclair:i u::.::. v:ar.:a::ities, either cxpres5ed o:-:m9lied 1 .:r.cludir,g Du:: not. ":.i.r:nted ::.o impllGd \··arra.nt.1.'c:s of progrum and a.c::::om?a:1~·ing cioct.:.:r.-.e'1.'::ation. I:1 no e"'ent shall C.lear Creek S0lu::.io1:s Inc. be ~iab.'..e :or an" damages -,r.atsoe··er tinclt.:.d::.ng 11 '..tho'..lt. :ll'.'.ltatio:1 to damo.ges for loss of business profits, loss cf bas1nc.sc; c..nforrr.ation, businE'ss '..nterruption, a~d the l~ke: arising out of the use of, or 1.nabilit~· :c ~se this program c··cn if ClcaL Creek Solutions Inc. or :heir author:ized representati .. es ha•·e been ad·:ised of the pos:;;ibility of sucJ-. dair,ai;es. softi,,are Cop~1right frl b~· Clear creek Solutions, lnC'. 2005-202.3; Al.l. Righ:s Reserved. ------·------·------·-··--------··----- Project Description Friction Method Solve For Input Data Roughness Coefficient Channel Slope Bottom Width Discharge Results Normal Depth Flow Area Wetted Perimeter Hydraulic Radius Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type GVF Input Data Downstream Depth Length Number Of steps GVF Output Data Upstream Depth Piofile Description Profile Headless Downstream Velocity Upstream Velocity Normal Depth Critical Depth Channel Slope Critical Slope 1/28/2014 7:15:26 AM Worksheet for Trench Drain· 107 -------~---------------------------. Manning Formula Normal Depth Subcritical 0.012 0.00500 ft/ft 0.50 ft o.6s ft'ts ......... 2 5 Yf2'.. 0.49 ft- 0.25 ft' 1.48 ft 0.17 ft 0.50 ft 0.37 ft 0.00987 ft/ft 2.64 ft/s 0.11 ft 0.60 ft 0.66 0.00 ft 0.00 ft 0 0.00 ft 0.00 ft Infinity ft/s Infinity ft/s 0.49 ft 0.37 ft 0.00500 ft/ft 0.00987 ft/ft n".ENC ti I"=> o.s· [)6€P MIN ---... / BenUey Systems, Inc. Haestad Methods SolllltmtlfilpfttewMasterVBi (SELECTserles 1) [08.11.01.031 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1 Project Description Friction Method Solve For Input Data Roughness Coefficient Channel Slope Normal Depth Left Side Slope Right Side Slope Results Discharge Flow Area Wetted Perimeter Hydraulic Radius Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type GVF Input Data Downstream Depth Length Number Of Steps GVF Output Data Upstream Depth Profile Description Profile Headless Downstream Velocity Upstream Velocity Normal Depth Critical Depth Channel Slope Critical Slope 1130/2014 12:52:43 PM --------- Worksheet for Swale Manning Formula Discharge Subcritical 0.027 0.00660 ft/ft --o>0.50 ft 2.00 ft/ft (H:V) 2.00 ft/ft (H:V) go U(.;+LT 1/3 or' S ,ra;- FLOWS -n+rz-ovc..~ 'Sk..)A"'-E. z_ 5 YIZ-15 M 1N .:>GAi:: Fu,w llVTO f'oN<=' ~ /,(32 C,f""S. /.62 CFY3 • 0,G, I CFS 0.82 ftS/g ,,. o.a., (].,FS V 0.50 ft' 2.24 fl 0.22 ft 2.00 ft 0.40 ft 0.02103 ft/ft 1.65 ft/s ·0.04 ft 0.54 ft 0.58 0.00 ft 0.00 ft 0 0.00 ft 0.00 ft Infinity ft/s Infinity ft/s 0.50 ft 0.40 ft 0.00660 ft/ft 0.02103 ft/ft 2S ,~ ~vG,uT-L-V I Lt___ FLolu t.;_; 1-n+ mot: E3' TH-14,v (p •. F~€c goA-12-P. BenUey Systems, lnc. Haestad Methods SollHmllCilfllHewMasterVSi (SELECTserles 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 . Page 1 of 1 Project Description Friction Method Solve For Input Data Roughness Coefficient Channel Slope Left Side Slope Right Side Slope Discharge Results Normal Depth Flow Area Wetted Perimeter Hydraulic Radius Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type GVF Input Data Downstream Depth Length Number Of Steps GVF Output Data Upstream Depth Profile Description Profile Headless Downstream Velocity Upstream Velocity Normal Depth Critical Depth Channel Slope Crltical Slope 1/30/20141 :08:45 PM -~~_Worksheet for Swale 1 OOy_r ______ _ Manning Formula Normal Depth Subcritical 0.027 0 00660 ft/ft 2.00 ft/ft (H:V) 2.00 ft/ft (H:V) 0.86 ft1'/s 0.51 ft- 0.52 ft' 2.27 ft 0.23 ft 2.03 ft 0.41 ft 0.02091 ft/ft 1 67 ft/s 0.04 ft 0.55 ft 0.58 0.00 ft 0.00 ft 0 0.00 ft 0.00 ft Infinity ft/s Infinity ft/s 0.51 ft 0.41 ft 0.00660 ft/ft 0.02091 ft/ft 'i:'ov,;ttl., y3, oF ,;.,[6 fLov-1:, r\Hwv,:;.,; "6w,<H£, /0 D i'I!. ,s "''"' ?G'i+"" A.Pw ,,vcc, ?<,/VP o Z-loOMS -z. .e,.o c,.s/g .-o,8(> (J.FS Pr,c tl-Lv/l.'-" No-r- ovs/L-<>~ A• JOO -;'~ t,Vc"-''f": Bentley System!!, Inc. Haestad Methods SoltuDrtl6'elllewMaster V81 (SELECTseries 1) [OB.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1.203-755-1666 Page 1 of 1 VANTAGE POINT· BACKWATER CALCULATIONS· TRUNK 100 ,,, (31 ,,, (51 161 "' 181 191 (10) (11) (12) (18) (19) (20) (21) (24) (26) (28) 1211 (3(1) (35A) (41) (42) Ell (45) 1C11 (47) Ell (50) (51) (55) (56) (57) (70) (71) (72A) .. (75) (76) (77) PIPE DESIGN WALL INC MANNINGS HEAD APPR YEAR PAVEMENT THICKN JUNCT MANNINGS CATCH FULL FLOW CAP VEL CRIT ATCRIT TAIL FRICT ENTR EXIT OUT IN VEL BEND JUNCT HEADW OVERTOP STORM STRUCTURE RIM THICKNESS DIAM E55 INVERT ANGL FLOW FULL FLOWV PVMT GRASS AREA TOTAL TC FLOW CAPACITY CHECK VEL HEAD DEPTH DEPTH WATER LOSS LOSS LOSS CTRL CTRL HEAD LOSS LOSS ATER CHECK Notes ue DOWN ue DOWN u, DOWS u, DOWN u, u, u, u, u, u, DOWN UP DOWN u, u, u, u, u, (YEAR) ® ® (FT) (FT) 1!-"!l 1!-"!l 1!-"!l 1!-"!l (FT) {FTI (DEG) (FTI % (CFS) lFPS} !AC) !AC) lACJ (MIN} (CFS! (CFS) (FPS) {FT) (FTI (FT) (FT) IFT) (FT) (FT) (FT( (FT) Q']l iFTI (~J .I!!! 25 TRENCH-107 CB-106 384A7 384m 0.00 0.00 • 0.00 382.99 382.67 0.00 0.012 78.75 0.41" 0.00 2.39 0.228 0.028 0.256 5.00 0.65 0.83 OI( 1.16 0.05 0.38 0.53 383.31 0.19 0.03 0.05 383.74 383.S6 0.00 0.00 0.00 m:u·: ··oi--, ------·------ " CB-106 CB-105 384.07 ..... 0.00 0.00 12 0.00 !182.'4 !182.23 84.40 0.012 26.17 0.42" o.oo 3.19 0.021 0.00, 0.024 5.00 0.71 , ... OK 0.,0 0.01 0.3S 0.'8 W.24 0.01 0.01 0.01 J83.36 382.H 0.05 0.06 0.00 383.37 OK " CB•l.05 CB•1D4 ,.. .. 38:-11.86 0.00 0.00 12 0.00 382.23 381.n 0.00 0.012 12&21 0.41" 0.00 3.U 0 .... ,...._ .ll.1151_ 5.00 0.84 '-" OK 1.0, O.D2 0.38 0.53 382.13 D.06 0.01 0.02 383.U 382-76 0.01 0.00 0.00 383.24 OK 2S CB· 104 ce.103 383.86 383.77 0.00 0.00 12 0.00 381.n 381.50 0.00 0,)12 52.30 o.-~00 3.11 0 .... 0.011 0.056 5.00 0.,, 2.45 OK 1.2' O.D2 0.41 0.57 382.52 0.03 ~01 O.D2 382.75 3B2.29 0.02 0.00 0.00 382.73 OK " CB· 103 ce-102 383.77 383.43 0.00 0.00 12 0.00 381,50 3S1.34 27.10 0.012 ..... 0.-~00 3.12 0.012 0.000 0.022 5.00 1.00 us OK 1.28 0.03 0.42 o~, 382.37 0.03 0.01 003 382.54 382.09 0.02 0.00 0.00 ,au, o, .. " C8·102 C8·101 383A3 385.37 o.oo ~00 12 0.00 ..... 381.00 22.30 0,)12 82.39 0.41% 0.00 3.16 0.075 0.012 0.087 5.00 1.22 '-" o, 1.55 0.04 0.47 0~5 382.11 0.00 0.02 004 382AO 3S2.01 0.03 0.00 0.00 '82-37 o, --- " CB·lOl CB·100 385.37 384.72 ~00 ~00 12 000 38LOO -81 91.20 0,)12 52.41 0.36% 0.00 2.96 0.123 0.038 0.162 ,_oo 1.59 ,.,, o, 2.02 0.06 0.53 075 381.8& 0.09 0.03 006 382.10 381.79 0_04 0.05 0.00 382.11 o, ' - " CB-100 IWNGARDEN 384.72 380.40 ~00 ~00 12 ~00 380.81 380.40 0.00 0.002 '4.07 0.44" 0.00 U4 0.047 0.005 0.062 5.00 1.72 255 o, 2.19 0.07 0.56 0.78 381.40 0.19 0.0< 007 381.92 381.64 O.o& 0.00 0.00 '81.86 o, -·-----·---.. --·--··--·· -----·---------- ---... 100 TRENOl-107 CB-106 38U7 384.07 0.00 0.00 ' ~00 ..,_., ..,.., 0.00 0.032 78.75 0.41% ~00 2.39 0.228 o.o,e 0."6 S.00 0.82 ,., OK 2-35 0.09 0.43 0.61 383.39 o.31 0.04 0.09 383.82 ...... o.oo o.oo o.oo m.az OI( 200 CB-106 CB-10! 384.07 ...... 0.00 0.00 12 000 382-'4 382-" 84.40 0.032 26-17 0.42% ~00 3.19 0.021 01)03 0.024 ~00 0.,0 , ... OK 1.14 0.02 0.40 0.5' 383.25 0.01 0.01 0.02 383.31 382.90 0.09 0.10 0.00 W.39 OI( 100 CB-105 C&-104 ,.... ...... 0.00 0.00 12 . ., 382-" ,.,_,, 0."1 0.012 1211.28 0.41% 0."1 3.13 0.045 0.006 0.051 5.00 1.06 2.46 OK 1.35 0.03 OA3 0.60 382.74 0.10 0.01 0.03 383.27 382.84 0.02 0.00 0.00 W.25 OK 100 CB· 104 Cl>-103 ...... 38377 0.00 0.00 12 ~., 382-71 ~ 0.00 o.ou 52-30 0 ..... ~00 3.11 0.045 0.011 ~056 5.00 1.ll us o, 1.56 ... .., 0.65 382.53 0.05 0.02 0.0< 382.77 382.38 0.03 I 0.00 0.00 382.74 OK 200 CB· 103 C8·102 383-77 383.43 0.00 0.00 12 0.00 ~ ...... 27.70 o.ou 39 ... 0.-~00 3.12 0.012 0.000 0.012 5.00 1.27 2AS o, 1.61 ... ... 0.66 382.39 0.0< 0.02 0.0< 382-56 382.18 0.04 I 0.01 0.00 382.53 OK 200 CB-102 C8-101 383A3 385.37 0.00 0.00 12 ~00 ...... 382-00 22.30 o.ou 82.39 0.41" ~., 3.16 0.075 o.ou ~087 5.00 .... 2.48 OK 1.96 O.Q6 0.53 0.74 382.20 0.13 0.03 0.06 382'3 382.11 0.0< 0.01 0.00 382.39 OK 200 CB-101 CB-200 385.37 384.72 0.00 0.00 12 0.00 383.QO 380.81 91.20 ~OU ,,_., 0.36% ~., '·" 0.123 .... U62 5.00 SOl 2.32 OK 2.56 0.10 0.60 0.86 381.89 0.1' o.os (1.10 382.18 381.92 0.06 0.08 0.00 382.20 o, I " 200 CB-100 RAINGARDEN 38472 380.40 0.00 0.00 u 0.00 38021 380.40 ~00 0.012 """' o ..... ~., 3.24 0.047 0.000 ~062 5.00 ue 2.55 OK 2.77 0.12 0.63 0.90 381.40 0-~-f-.!~ 0.12 381.99 381.78 0.10 o.oo 0.00 381.89 o, ~ r---·· ··t- ' --__ _;_ ----·--... ' ' _ .. _, __ _ __ ,, ______ --... ·--·'"T"'··--1--· ' --f------+-·-----' --- I------ I --- ' -~ ' ' ' ' ----·""'"'" r-.. ------"--·---... _ -· ,--. i--·-i----· --·--·----. ---· ·--·· -----·----'-----··--------~L---- X:\113001-113250\1131 88 {Vantage Glen)IPROJECT DOCUMENTS\Storm Drainage\Detention & Conveyance Calculabons\Backwater.xlsm 111 DESIGN YEAR STORM (YEAR) 25 2S 25 25 25 25 25 100 100 100 100 100 100 100 • VANTAGE POINT· BACKWATER CALCULATIONS· ROW UPSTREAM ANALYSIS (3) (4) (5) (6) (9) (11) (12) (18) (19) (20) (21) STRUCTURE RIM DIAM INVERT ANGL UP DOWN UP DOWN UP DOWN UP !!! 1!l (FT) (FT) ~ (FT) .LFJ) _ (p_~G_) (FT) % (8#7376 C8#7230 "'8.16 388.lS 12 384.52 383.26 0.00 0.012 34.46 3.66% C8#7230 CB#7076 388.15 383.27 12 383.26 379.69 0.00 0.012 176.13 2.03% C8#7076 CU7ll59 383.27 381.11 l2 379.&2 J71.fi6 0.00 0.012 """" 0.1111% C8#7059 CB#7S7S 381.71 380.36 12 377.61 376.20 0.00 0.012 173.00 0.82% CB#7575 CB#8057 380.36 378.89 12 376.16 374.66 0.00 o.ou 199.36 0.75% CBl8057 CB-1201 378.89 378.88 12 374.66 m.so o.oo O.Oll 18.60 11.61% CB-1201 CB-1200 378.88 377.85 12 372.50 372.01 0.00 0.012 48.92 1.00% C8#7376 C8#7230 388.16 388.15 12 384.52 383.26 0.00 0.012 34.46 3.66% CB#7230 C8#7076 388.15 383.27 12 383.26 379.69 0.00 0.012 176.13 2.03% CB#7076 CB#7059 383.27 381.71 12 379.62 ID.66 0.00 O.OU 221.93 0.88% CB#7059 CB#7S75 381.71 380.36 12 377.61 376.20 0.00 0.012 173.00 0.82% C8#7575 CB#81157 380.36 378.89 12 376.16 374.66 0.00 0.012 199.36 0.75% CBl8057 CB-1201 378.89 378.88 12 374.66 372.50 0.00 0.012 18.60 11.61% CB-1201 CB-1200 378.88 377.85 12 372.50 372.01 0.00 0.012 48.92 1.00% (241 {26) (281 (291 (301 l35AI INC MANNINGS JUNCT FULL FLOW CATCH (41) 1421 El (45) ID 1"1 11111 1,01 (51) (55) (56) (57) MANNINGS HEAD FULL FLOW CAP VEL CRIT AT CRIT TAIL FRICT ENTR EXIT OUT (70) (71) (72A) -(75) (76) APPR IN VEL BEND JUNCT HEADW OVERTOP FLOW UP V PVMT GRASS AREA TOTAL TC FLOW CAPACITY CHECK VEL HEAD DEPTH DEPTH WATER LOSS LOSS LOSS CTRL CTRL HEAD LOSS LOSS ATER CHECK UP UP UP UP DOWN UP DOWN UP UP UP UP UP jCF~! [FPS) (AC) (AC) (AC) [MIN) (CFS) (CFS) J~P~) __ 1_~) _l':_"!") , .. , {F~) , .. , _\~ , .. , (F!l , .. , im ,. -, (Fl) LFT) , .. , (FT) ,--, (FT) , .. , (FT) (FT) , .. , (FT) ,--, 0.00 9.40 0.120 0.0:ZO 0.140 5.00 0.35 , ... OK 0.44 0.00 0.24 0.33 384.27 0.00 o.oo 0.00 385.52 384.83 0.00 0.00 0.00 385.52 OK 0.00 7.00 0.086 0.000 0.086 5.00 0.58 5.50 OK 0.74 0.01 0.32 OA3 380.67 0.04 0.00 0.01 384.27 383.69 0.00 0.00 0.00 384.27 OK 0.00 4.62 0.213 0.06!> 0.282 5.00 1.22 3.63 OK 1.56 0.04 0.47 0.65 378.71 0.22 0.02 0.04 380.68 380.29 0.01 0.00 0.00 380.67 OK 0.00 4.44 0.244 O.OS2 0.296 5.00 1.93 3.48 OK 2.46 0.09 0.59 0.84 3n.35 0.43 0.05 D.09 378.75 378.51 0.04 0.00 0.00 378.71 OK 0.00 4.26 0.278 0.043 0.321 5.00 2.73 3.35 OK 3.48 0.19 0.71 1.04 375.92 1.00 0.09 0.19 377.44 377.31 0.09 0.00 0.00 377.35 OK o.oo 16.75 0.234 O.OS3 0.287 5.00 3.42 13.15 OK 4.35 0.29 0.79 1.20 373.70 0.15 0-15 0.29 376.10 376.03 0.19 D.00 0.00 375.92 OK 0.13 4.92 0.000 0.000 0.000 5.00 3.54 3.86 OK 4.51 0.32 0.80 1.23 372.91 0.41 0.16 0.32 373.97 373.98 0.29 0.01 0.01 373.70 OK 0.00 9.40 0.120 0.020 0.140 5.00 D.44 7.38 OK 0.56 0.00 0.27 0.37 384.28 0.00 0.00 D.00 385.53 384.88 D.00 0.00 D.00 385.53 OK 0.00 7.00 0.086 0.000 0.086 5.00 0.73 5.50 OK 0.94 0.01 0.36 DA9 380.70 0.()fi 0.01 0.01 .384.28 383.75 D.00 0.00 D.00 384.28 OK 0.00 4.62 0.213 0.069 0.282 5.00 1.SS 3.63 OK 1.97 D.06 o.53 0.74 378.96 0.36 0.03 0.06 380.71 380.39 0.01 o.oo D.00 380.70 OK 0.00 4.44 0.244 0.052 0.296 5.00 2.45 3.48 OK 3.12 0.15 0.67 D.97 378.09 0.70 0.08 0.15 379.02 378.67 0.06 0.00 D.00 378.96 OK 0.00 4.26 0.278 0.043 0.321 5.00 3.46 3.35 ...... 4.41 0.30 0.80 1.21 376.19 1.60 0.15 0.30 378.24 3n.60 0.15 0.00 D.00 378.09 OK 0.00 16.75 0.234 0.053 0.287 5.00 4.33 13.15 OK 5.51 0.47 0.87 1.42 374.00 0.23 0.24 0.47 376.37 376.48 0.30 0.01 D.00 376.19 OK 0.13 4.92 0.000 0.000 0.000 5.00 4.46 3.86 -:Ml-5.68 0.50 0.88 1.46 372.95 0.65 0.25 0.50 374.36 374.45 0.47 0.01 0.01 374.00 OK ·---·--·---------·-·----··-----· X:\ 113001-113250\113188 (Van1age Glen)\PROJECT DOCUMENTS\Storm Drainage\Detention & Conveyance Calculalions\Backwater ROW.xlsm (77) Nates ' i . ·-····--- ---------~-----~~--- Appendix C Special Reports and Studies Vantage Point Apartments Technical Information Report Appendix C CORPORATED AREAS 530071 / .T // - ZONE X I I G SOUTHEAST >-~ " w I >-=> 0 ~ w V :l "- I ~, 32 SITE >-~ w I >-=> ~ w => 2 w > " I Ii; ,' 176TH STREET ~ I 5 0 ~ w ::, z w ~ I 13 := • APPROXIMATE SCALE IN FEET 500 0 500 NATIONAL FLOOD INSURANCE PROGRAM FLOOD INSURANCE RATE MAP KING COUNTY, WASHINGTON AND INCORPORATED AREAS PANEL 979 OF 1725 !SEE MAP INDEX FOR PANU~ 'IOI rHINTEDi M~MOCR P/\NEL SUFFIX 5JOO'IO 091S oJOOn co,,9 SJ00011 osm MAP NUMBER 53033C0979 F MAP REVISED: MAY 16, 1995 Federal Emergency Management Agency This is an official copy of a portion of the above referenced flood map It was extracted using F-MIT On-Line. This map doee not reflect changes or amendments which may haYe been made subsequent to the date on the title block. For the latest product information aOOut National Flood Insurance Program flood maps check the FEMA Flood Map Store at WWW mac fema.gov REPORT OF GEOTECHNICAL ENGINEERING SERVICES Vantage Point -Multi-Family Rental Project Vantage Glen Community 17901 l OS" Place SE Renton, Washington For Vantage Point Apartments LLC c/o King County Housing Authority February 18, 2014 GeoDesign Project: KCHA-29-03 DRAFT February 18, 2014 Vantage Point Apartments LLC c/o King County Housing Authority Capital Construction Department 625 Andover Park West, Suite 107 Seattle, WA 98188 Attention: Mr. Tim Locke DRAFT Report of Geotechnical Engineering Services Vantage Point -Multi-Family Rental Project Vantage Glen Community 17901 105"' Place SE Renton, Washington GeoDesign Project: KCHA-29-03 GeoDesign, Inc. is pleased to submit this report that summarizes our geotechnical engineering services to support the development of multi-family housing at the Vantage Glen Community in Renton, Washington. This report has been prepared in accordance with discussions, our proposal dated November 15, 2013, and in conjunction with our report entitled Report of Geotechnical Engineering Services; Vantage Glen -Multi-Family Rental Project; Vantage Glen; 17901 105"' Place SE; Renton, Washington, dated March 21, 2013 . • • • DRAFT We appreciate the opportunity to be of service to you. Please contact us if you have questions regarding this report. Sincerely, GeoDesign, Inc. [DRAFT] Thomas A. Tobin, P.E. Principal Engineer cc: Ms. Pam Derry, Tonkin/Hoyne Architecture & Urban Design (via email only) Mr. Alberto Cisneros, KPFF Consulting Engineers (via email only) Ms. Anna Nelson, Van Ness Feldman LLP (via email only) TAP:TAT:kt Attachments One copy submitted (via email only) Document ID: KCHA·29-03·02 l 8l 4-geor-DRAFT.docx © 2014 GeoDesign, Inc. All rights reserved. 2 KCHA-29-03:021814 TABLE OF CONTENTS 1 .0 INTRODUCTION 2 .0 PURPOSE AND SCOPE OF WORK 3.0 4.0 5.0 6.0 7.0 8.0 SITE CONDITIONS 3.1 General 3.2 3.3 Surface Conditions Subsurface Conditions 3.4 Groundwater INFILTRATION TESTING LABORATORY TESTING DESIGN RECOMMENDATIONS 6.1 General 6.2 Seismic Design Criteria 6.3 Foundation Support -Shallow Spread Footings 6.4 Concrete Slab on Grade 6.5 6.6 Below-Grade Walls and Retaining Walls Stormwater Infiltration Evaluation 6.7 Pavement Design SEWER IN STEEP SLOPE AREA 7. l Slope Topography 7.2 Subsurface Soils 7.3 Sewer Pipeline Recommendations 7.4 Erosion Protection SITE DEVELOPMENT 8.1 8.2 8.3 8.4 8.5 Site Preparation Excavation Fill Materials Geosynthetics Construction Stormwater Considerations 8.6 Wet Weather Considerations 9.0 OBSERVATION OF CONSTRUCTION 10.0 LIMITATIONS REFERENCES FIGURES Vicinity Map Site Plan 1985 Aerial Photograph of Vantage Glen Site Site Area Modified by Previous Legal Grading Existing Steep Slope and Erosion Hazard Areas New Steep Slope and Erosion Hazard Areas rfflDESIGN:' DRAFT PAGE NO. 2 2 2 3 4 4 4 5 5 6 7 9 10 12 13 19 19 20 20 22 23 23 25 25 27 28 28 29 30 31 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 KOiA-29-03:021814 TABLE OF CONTENTS APPENDICES Appendix A Field Explorations Laboratory Testing Exploration Key Soil Classification System Boring Logs Grain-Size Test Results Summary of Laboratory Data Appendix B Prior Exploration Logs Appendix C Analytical Resources, Inc. Laboratory Report ACRONYMS DRAFT PAGE NO. A-1 A-1 Table A-1 Table A-2 Figures A-1 · A-5 Figure A-6 Figure A-7 KCHA-29-03:021814 DRAFT 1.0 INTRODUCTION This report presents the results of GeoDesign's geotechnical engineering services for the development of multi-family housing at the Vantage Glen Community in Renton, Washington. The Vantage Glen Community is located south and west of the intersection of SE l 80"' Street and l OS"' Place SE. The existing Vantage Glen Community consists of single-family manufactured homes and a community center. We understand the proposed development will be multi-family housing. As currently planned, the housing will include the construction of multi-story apartments and associated infrastructure (parking and utilities). We understand that significant site grading is anticipated to include excavations for below-grade parking under the buildings and construction of a stormwater management pond. Our proposal was submitted to KCHA on November l 5, 2013 and subsequently approved by contract number CD1 l 0016S, Task Order Number 18, dated November 25, 2013. Our initial geotechnical report was submitted to KCHA on March 21,2013. This updated report is issued to provide additional recommendations for new and/or revised project considerations that have arisen as the project design evolved. We also updated the Geologic Hazards Report for the project. The original report was issued on February 27, 2013; the updated report was issued on January 16, 2014. For your reference, definitions of all acronyms used herein are defined at the end of this document. 2.0 PURPOSE AND SCOPE OF WORK The purpose of this study was to complete additional subsurface explorations and provide additional geotechnical recommendations for the final design phase. Our scope of work included conducting a site reconnaissance, drilling and sampling five exploratory borings, performing laboratory testing, and completing engineering analyses to develop the geotechnical conclusions and recommendations presented in this report. Specifically, we performed the following: • Collected and reviewed readily available geotechnical and geological data for the project area. • Reviewed our existing report, including historical aerial photographs of the site, to identify areas where historical grading or mining has taken place and to identify slopes created by those activities. • Coordinated and managed the field investigation, including public utility locates and scheduling of contractors and GeoDesign staff. DDESIGN<' KCHA-29-03:021814 DRAFT • Completed the following explorations to evaluate the subsurface conditions at the site: • Five additional borings to depths of up to 61.5 feet BGS o Performed infiltration tests in the augers at the approximate elevation of the base of the pond o Installed a well to a depth of 60 feet BGS to monitor high groundwater levels during the wet season • Completed laboratory analyses on selected disturbed soil samples obtained from the explorations to determine certain index properties of the on-site soil. • Performed engineering analyses and evaluated data derived from the subsurface investigation and laboratory testing program. • Prepared this report summarizing our findings, conclusions, and recommendations related to the following: • Subsurface soil and groundwater conditions and results of laboratory testing • Estimate of preliminary infiltration rates for design of the infiltration pond, including laboratory testing to evaluate water quality treatment capacity of native soils based on CEC and organic matter content testing • Groundwater mounding analysis to determine the effect of the infiltration pond on the surrounding properties • Slope analysis with post-pond groundwater levels • Waterproofing recommendation for the below-grade parking basement walls • Hillside pipeline recommendations • Underslab drainage recommendations • Grasscrete pavement evaluation GeoDesign's scope of work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the soil, surface water, or groundwater at this site. 3.0 SITE CONDITIONS 3.1 GENERAL The Vantage Glen Community is located south and west of the intersection of SE 180'" Street and l 05" Place SE. The proposed multi-family housing project site includes the two adjoining undeveloped parcels to the north and the east of the existing communities (parcel numbers 3223059363 and 3223059362). The two parcels form an "L" shape (approximately 5 acres in size), a portion of which is bordered by l 80" Avenue SE to the north and l 05" Place SE to the east, an apartment complex on the north, and by the KCHA Vantage Glen residential community on the west and south. Surficial conditions were determined from observations during several visits to the site. Subsurface conditions throughout the site were evaluated by completing our explorations. 3.2 SURFACE CONDITIONS The site is located on a slope that ascends gradually upwards from SE 180" Street and 105" Place SE to a ridge that generally defines the western and southern boundary between the two undeveloped parcels. West and south of the ridge, the ground descends steeply down to the DDESIGN2 2 KCHA-29·03:021814 DRAFT backyards of the Vantage Glen Community homes on 1 04• Avenue SE and SE 181" Street. The slope gradients in this area vary from 40 percent to approximately 60 percent, with a change in elevation varying from 30 to 45 feet, and the slope meets the definition for steep slope geologic hazard areas as defined by the King County land use codes. We concluded that the Vantage Glen property and surrounding undeveloped parcels owned by KCHA have been extensively graded during past aggregate mining activities on the property and that the slopes were created as a result of mining activity. 3.3 SUBSURFACE CONDITIONS Subsurface conditions were explored within the proposed development area by drilling four borings during the initial phase of work at the site conducted during February 2013. We also completed 11 test pits during the initial phase. Those borings and test pits were documented in our March 21, 2013 report and are included herein for completeness. The recent explorations included drilling five additional borings (B-5 through 8-9) to depths ranging between 16.5 and 61.5 feet BGS in December 201 3. Borings 8-5 through 8-7 were completed in the area of the proposed infiltration pond. Initially, the borings were drilled to a depth of 12.0 feet BGS where infiltration tests were performed. The borings continued to a depth of 31.5 feet BGS in 8-5 and 8-7 and to 61.5 feet BGS in boring B-6. Borings 8-8 and 8-9 were completed along the slope on the western portion of the site. The exploration locations are shown on Figure 2. Descriptions of the field explorations, exploration logs, and laboratory procedures for the additional explorations are included in Appendix A of this report. Exploration logs for the initial phase of work are presented in Appendix B. Subsurface conditions encountered at the boring locations are generally consistent with the subsurface conditions described in our report dated March 21, 2013. The soils encountered in the bottom of the pond and along the western slope are described below. 3.3.1 Infiltration Pond Unengineered fill was encountered in the borings located in the pond area to a depth of approximately 1 foot BGS. The fill generally consist of silt with varying amounts of sand, gravel, and construction debris and silty sand with minor gravel. Beneath the fill, native soil was encountered. The native soil consists of intermixed sand, silt, and small amounts of gravel that were deposited by glaciers. The sand is medium dense to very dense and the silt is stiff to very stiff or hard. 3.32 Western Slope The soil along the slope on the western side of the site consists of sand with varying amounts of silt and sandy silt with varying amounts of gravel. The sand is dense to very dense and the sandy silt encountered in the upper 8 feet of B-8 is stiff. RDESIGNi 3 KCHA-29-03:021814 DRAFT 3.4 GROUNDWATER Groundwater was encountered in boring B-6 at approximately 45 feet BGS during drilling. A well was installed to a depth of 60.0 feet BGS. The groundwater level datalogger was installed in the well so that water levels can be obtained throughout the wet season to determine the seasonal high groundwater level. 4.0 INFILTRATION TESTING Infiltration testing was performed at the three borings in the pond area. The testing was completed in general accordance with the EPA falling head percolation test procedure provided in the King County 2009 SWDM (King County, 2009). The tests were performed at a depth of approximately 12 feet BGS or the approximate depth of the infiltration facility. Several tests were completed at each location after the saturation period. The test results are presented in Appendix C. 5.0 LABORATORY TESTING Laboratory tests were conducted on specific soil samples selected from the explorations to assist in characterizing certain physical parameters of the soil. Index tests that were performed included the determination of natural water content and grain-size distribution determinations. These tests were performed in GeoDesign's accredited soils laboratory. All tests were conducted in general accordance with appropriate ASTM standards (ASTM, 2011 ). A discussion of laboratory test methodology and test results are presented in Appendix A. Test results are also displayed where appropriate on the exploration logs in Appendix A. CEC and organic matter tests were completed on samples located at or near the anticipated base of the infiltration facility to evaluate soil capacity for water quality treatment. The CEC tests and organic matter tests were performed by Analytical Resources, Inc. A summary of test results is provided in Table 1. The test results are presented in Appendix B. Table 1. Soil Analytical Results Summary 1 Boring Sample Depth CEC' Organic Content (feet BGS) (meq per 100 grams) (percent) B-5 15.0 8.6 0.7 B-6 15.0 7.4 0.6 B-7 15.0 7.7 0.9 1. Suitability for Water Quality Treatment: CEC greater than 5 meq per 100 grams and organic matter content a minimum of 0.5 percent (King County, 2009) •DESIGN: 4 KCHA-29-03:021814 DRAFT 6.0 DESIGN RECOMMENDATIONS 6.1 GENERAL Based on our review of available information; the development history of the site; and the results of our explorations, laboratory testing, and analyses, it is our opinion that the site is suitable for construction of the proposed multi-family housing project and associated improvements. The following are key considerations for this development: • The Puget Sound area is a seismically active region. The dense, glacially consolidated material underlying the site at depths below l 0.0 to 1 5 .0 feet SGS is not conducive to amplifying earthquake ground motions and is not susceptible to liquefaction or lateral spreading. We did not observe evidence of faults on the site in the explorations or on geologic maps of the area and have concluded that the probability of surface rupture is low. We have provided appropriate seismic design recommendations based on the 2012 IBC criteria. • Fill that is unengineered was encountered over much of the site. The fill is less than 5 feet thick over much of the site; however, it ranges to as much as 1 3 feet thick in the area west of the intersection of SE 180" Street and l 05" Place SE. The fill frequently contains some localized demolition rubble and debris. This fill is not suitable for direct support of the structures and must be removed and replaced with compacted structural fill for adequate building support. Alternatively, the fill could be penetrated with an intermediate subsurface ground improvement system (such as rammed aggregate piers or stone columns) to provide adequate support for the building foundations and slabs-on-grade. The fill can remain in place outside ofthe building areas. • Where deeper fill is not present, shallow spread footing foundations bearing on an improved subgrade, prepared as recommended in the "Foundation Support -Shallow Spread Footings" section of this report, will provide adequate support for the proposed buildings. • The building floor slab can be supported on grade, provided the subgrade is prepared as recommended in the "Concrete Slab on Grade" section of this report. • We recommend installing an underslab drainage collection and discharge system below the slabs. The underslab drainage system should consist of at least 12 inches of l .5-inch-minus clean crushed gravel with negligible sand or silt /WSS 9-03. l (4)C, Grading, No. 5 7). The gravel layer should be placed between deepened foundation elements or below the slab/mat foundations, but should not be placed below the deepened foundation elements. • Retaining walls will be required to support the west margin of the Grasscrete access road around the west side of the building and at other locations where grade transitions cannot be sloped. Recommendations are presented for MSE walls and concrete cantilever retaining walls. RDESIGNi 5 KCHA-29·03:021814 • Sufficient separation of more than 5 feet exists between the anticipated bottom of the infiltration pond and the groundwater table and confining layers. The separation is necessary to support infiltration and avoid groundwater mounding. DRAFT • Soil exposed at the anticipated base of the infiltration pond will consist of sandy silt interbedded with silty sand. We recommend a design long-term infiltration rate of 0.4 inch per hour for design of the infiltration pond. • The soil below the base of the infiltration pond meets the soil suitability criteria for stormwater treatment. The King County 2009 SWDM soil suitability criteria requires a CEC of at least 5 meq per 100 grams and an organic content of at least 0.5 percent. • Both traditional HMA and pervious HMA pavements are planned for this project. Recommendations are presented for the following pavement sections. • Traditional HMA pavement will be used to construct the access driveways and the drive aisles in the parking areas. • Pervious HMA will be used in the parking stall areas. • A perimeter emergency access road around the west and south sides of the main building will be surfaced with Grasscrete. • A perimeter emergency access road around the west and south sides of the main building will be surfaced with Grasscrete. A summary of our evaluation of the Grasscrete pavement is included in this report. • Recommendations for the construction of the sewer in the steep slope are presented. Recommendations include site preparation, pipe construction, erosion control, and securing and bedding recommendations. We are currently finalizing our evaluation of groundwater mounding at the stormwater infiltration pond site. The results of the mounding analysis will be included in our final report. Our specific recommendations for design and guidelines for development of the site are presented in the following sections of this report. These should be incorporated into design and implemented during construction of the proposed development. 6.2 SEISMIC DESIGN CRITERIA Moderate to high levels of earthquake shaking should be anticipated during the design life of the building, and it should be designed to resist earthquake loading in accordance with the methodology described in the 2012 IBC. The recommended seismic design parameters for the proposed residential buildings, based on the 2012 IBC, are presented in Table 2. RDESIGN, 6 KCHA-29-03:021814 DRAFT Table 2. IBC Seismic Design Parameters Seismic Design Parameter Short Period I ·Second Period MCE Spectral Acceleration S = 1.393 g ' s, =0.519g Site Class C Site Coefficient F = I F = 1.364 • • Adjusted Spectral Acceleration s., = 1.393 g s., = 0.675 g Design Spectral Response Acceleration Parameters sos= 0.929 \, = 0.450 g 6.3 FOUNDATION SUPPORT -SHALLOW SPREAD FOOTINGS 6.3.1 General Conventional shallow spread footings will provide adequate support for the anticipated building loads. Loose to medium dense and/or soft to very stiff fill was typically encountered to depths ranging between 1 .0 and 1 3.0 feet BGS. Laboratory tests indicate that the moisture content of the fill is significantly above the optimum moisture content. Subgrade improvement measures that consist of over-excavation and replacement of a portion of the unengineered fill below foundation elements will be necessary to provide adequate foundation support. We recommend fully over-excavating the existing fill and re-compacting the material as structural fill. Any rubble or debris should be removed from the fill material prior to replacing it as structural fill. The structural fill should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 6.32 Dimensions and Capacities Continuous and isolated spread footings should be at least 18 and 24 inches wide, respectively. The bottom of exterior footings should be at least 18 inches below the adjacent exterior grade for frost heave protection. Interior footings should be founded a minimum of 12 inches below the lowest adjacent soil grade. Foundations supported on the properly prepared subgrade may be designed for an allowable bearing pressure of 3,500 psf. This is a net bearing pressure; the weight of the footing and overlying backfill can be ignored in calculating footing sizes. The recommended allowable bearing pressure applies to the total of dead plus long-term live loads and may be increased by one-third to account for short-term live loads such as induced by wind or seismic forces. 6.3.3 Resistance to Sliding Wind, earthquakes, and unbalanced earth loads will subject the proposed buildings to lateral forces. Lateral loads on footings can be resisted by passive earth pressure on the sides of the buried portions of the foundations and by friction on the base of the footings. An allowable passive resistance may be calculated as a triangular equivalent fluid pressure distribution using 7 KCHA-29·03:021814 DRAFT an equivalent fluid density of 350 pcf, provided the footings are surrounded with properly placed and compacted structural fill and the footing is above the groundwater table. Adjacent floor slabs, pavements, or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive resistance. For footings in contact with structural backfill, a coefficient of friction equal to 0.40 may be used. A safety factor of 1 .5 has been applied to the recommended sliding friction and passive pressure. 6.3A Settlement We estimate that total post-construction static (consolidation-induced) settlement for conventional and semi-rigid foundation systems should be less than 1 inch, with differential settlement of up to J.S inch measured along 25 feet of continuous wall footings or between similarly loaded adjacent footings. We expect that settlement for these conditions will tend to occur rapidly after the loads are applied. Immediately prior to placing concrete, all debris and soil slough that accumulated in the footings during forming and steel placement must be removed. Debris or loose soil not removed from the footing excavations will result in increased settlement. 6.3.5 Footing Drains We recommend that footings and basement walls around the buildings be provided with drainage to help manage potential perched groundwater in the upper fill and native soil. Footing drains can consist of free-draining material or prefabricated drainage panel products, with perforated pipes to discharge the collected water. Drainage behind basement walls is described in the "Below-Grade Walls and Retaining Walls" section of this report. The free-draining material should consist of drain rock as specified in the "Fill Materials" section of this report. Alternatively, the free-draining material can consist of clean gravel; however, the gravel should be fully encapsulated within a suitable geotextile filter fabric, such as Mirafi 140N (or similar material). The drainage material should be at least 1 foot wide and extend from the base level of the footing to within 1 foot of the ground surface. The free-draining material should be capped with less permeable material, such as the on-site soil. Prefabricated drainage panel products, such as Mirafi Miradrain 6000 (or similar material), consist of a geotextile filter fabric bonded to a molded plastic drainage element. The drainage panel is placed directly against the footing and stem wall and should extend from the base level of the footing to approximately 1 foot from finished grade. The panel should also be covered with 1 foot of less permeable material, such as the on-site soil. Footing drains should include a 4-inch-diameter, perforated solid pipe or rigid corrugated polyethylene pipe (ADS N-12 or equal) near the base level of the footing. Where free-draining material is used, the pipe should be installed with approximately 3 inches of drainage material below the pipe. With drainage panels, the geotextile filter fabric should extend from the panel to wrap around the pipe. The pipes should be laid with minimum slopes of Y.; percent and discharge into a sump or a water collection system to convey the water away from the building. 8 KCHA-29-03:021814 DRAFT The pipe installations should include cleanout risers located at the upper end of each pipe run. We recommend that the cleanouts be covered and placed in flush-mounted utility boxes. We recommend that roof downspouts not discharge into the footing drain perforated pipes. 6.4 CONCRETE SLAB ON GRADE 6.4.1 General Conventional slabs may be supported on grade, provided the subgrade soil is prepared as recommended in "Fill Materials" section of this report. We recommend that the slab be founded on structural fill. For slabs designed as a beam on an elastic foundation, a modulus of subgrade reaction of 1 50 pci may be used for subgrade soil prepared as recommended. We recommend that exterior slabs, such as those for walkways, be structurally independent from the structure foundations. This will allow minor movement of the slabs to occur as a result of vehicular loading, tree root growth, seasonal soil shifting, and other factors, while reducing the potential for slab cracking around the perimeter. Interior slabs may be tied to the structure's foundation system. 6.42 Underslab Drainage Water seepage and accumulation beneath the basement floor slabs could result in a wet floor condition and/or uplift pressures on the floor slabs. To help prevent this, we recommend installing an underslab drainage collection and discharge system below the slabs. The underslab drainage system should consist of at least 12 inches of 1.5-inch-minus clean crushed gravel with negligible sand or silt (WSS 9-03.1 (4)C, Grading, No. 57}. The gravel layer should be placed between deepened foundation elements or below the slab/mat foundations, but should not be placed below the deepened foundation elements. A network of minimum 4-inch-diameter perforated collector pipes should be placed at the base of the gravel and should be spaced 20 feet on center. The drainage collector pipe should be either machine slotted or perforated. The underslab drainage system pipes should be routed to discharge into a sump to pump the collected water to the site drainage facilities. We recommend using either heavy-wall solid pipe (SDR-35 PVC) or rigid corrugated polyethylene pipe (ADS N-12, or equal) for the collector pipes. We recommend against using flexible tubing for collector pipes. A geotextile filter fabric should be placed between the 12-inch-thick gravel layer and the native soil subgrade to maintain separation and reduce piping of the fine-grained soil up into the gravel. The geotextile should be non-woven and conform to the specifications for Class A, underground drainage material provided in WSS 9-33.2(1) -Geotextile Properties, Table 2 Geotextile for Underground Drainage. The geotextile should be installed in conformance with the specifications provided in WSS 2-12 -Construction Geosynthetic. The amount of groundwater flow entering the underslab drainage system in each basement area is not expected to be significant. We estimate that the flow from a passive drainage system under each basement slab area will typically be in the range of 1 to 2 gpm, depending on the depth of the final structure configuration. If the basement wall backdrains are routed to the (fflDESIGN2 9 KCHA-29-03:021814 DRAFT same sumps, the flow combined amounts should be increased to approximately 2 to 4 gpm. However, we recommend that the sumps be sized to accommodate larger pumps if larger flows are experienced. To help prevent basement slab and wall wetness, we recommend that the slabs and walls be waterproofed. The waterproofing should be designed by a waterproofing expert. 6.5 BELOW-GRADE WALLS AND RETAINING WALLS 6.5.1 General The following recommendations should be used for the design of below-grade walls that are intended to act as retaining walls and for other retaining structures that are used to achieve grade changes. 6.52 Design Parameters Lateral earth pressures for design of below-grade walls and retaining structures should be evaluated using an equivalent fluid density of 35 pcf, provided that the walls will not be restrained against rotation when backfill is placed. If the walls will be restrained from rotation (i.e., basement walls internally braced by the floor slabs), we recommend using an equivalent fluid density of 55 pcf. Walls are assumed to be restrained if top movement during backfilling is less than H/1,000, where H is the wall height. These lateral soil pressures assume that the ground surface behind the wall is horizontal. For unrestrained walls with backfill sloping up at 2H: 1 V, the design lateral earth pressure should be increased to 55 pcf, while restrained walls with a 2H:1V sloping backfill should be designed using an equivalent fluid density of 75 pcf. These lateral soil pressures do not include the effects of surcharges such as floor loads, traffic loads, or other surface loading. Below-grade walls for the buildings should also include seismic earth pressures. Seismic earth pressures should be determined using a rectangular distribution of 7H psf, where H is the wall height. If vehicles can approach the tops of exterior walls to within one-half the height of the wall, a traffic surcharge should be added to the wall pressure. For car parking areas, the traffic surcharge can be approximated by the equivalent weight of an additional 1 foot of soil backfill (12 5 psf) behind the wall. For truck parking areas and access driveway areas, the traffic surcharge can be approximated by the equivalent weight of an additional 2 feet (2 SO psf} of soil backfill behind the wall. The fire-fighting apparatus may impose higher surcharge loads than conventional trucks. We should review these loads to evaluate the wall surcharges during final design of the walls. Other surcharge loads, such as from foundations, construction equipment, or construction staging areas, should be considered on a case-by-case basis. These recommendations are based on the assumption that adequate backdrainage will be provided behind below-grade walls and retaining structures as discussed below. The values for soil bearing, frictional resistance, and passive resistance presented above for foundation design are applicable to retaining wall design. Walls located in level ground areas should be founded at a depth of 1 8 inches below the adjacent grade. An exception to this is for walls sited in close proximity to descending ground. If the ground descends at a slope of 2H:1 V below a wall, a RDESIGNC 10 KOIA-29·03:021814 DRAFT minimum embedment depth of 4 feet will be required. The allowable passive resistance of the soil on the toes of these walls is also reduced for conditions where the ground descends below the wall. For a 2H:1 V descending slope, no passive resistance can be allowed for the upper-most 2 feet of embedment and a reduced allowable passive resistance of 1 50 psf can be used on the lower 2 feet of embedment. 6.5.3 Backdrainage To reduce the potential for hydrostatic water pressure buildup behind the retaining walls, we recommend that the walls be provided with backdrainage. Backdrainage can be achieved by using free-draining material with perforated pipes to discharge the collected water. Positive drainage should be provided behind below-grade walls and retaining walls by placing a minimum 2-foot-wide zone of free-draining backfill directly behind the wall. The free-draining backfill should meet the criteria for WSS 9-03.12(2) -Gravel Backfill for Walls. The free-draining backfill zone should extend from the base of the wall to within 2 feet of the finished ground surface. The top 2 feet of fill should consist of relatively impermeable soil to prevent infiltration of surface water into the wall drainage zone. A 4-inch-diameter perforated drainpipe should be installed within the free-draining material at the base of each wall. We recommend against using flexible tubing for the wall drainpipe. The footing drain recommended above can be incorporated into the bottom of the drainage zone and be used for this purpose. The pipes should be laid with minimum slopes of 0.5 percent and discharge into a sump or the stormwater collection system to convey the water off site. The pipe installations should include a cleanout riser with cover located at the upper end of each pipe run. The cleanouts could be placed in flush-mounted access boxes. We recommend against discharging roof downspouts into the perforated pipe providing wall backdrainage. Collected downspout water should be routed to appropriate discharge points in separate pipe systems. For exterior walls where seepage at the face of a wall is not objectionable, the walls can be provided with weep holes to discharge water from the free-draining wall backfill material. The weep holes should be 3 inches in diameter and spaced approximately every 8 feet center-to- center along the base of the walls. The weep holes should be backed with galvanized heavy wire mesh to help prevent loss of the backfill material. 6.5.4 Construction Considerations Exterior retaining walls used to achieve grade transitions or for landscaping can be constructed using traditional structural systems such as reinforced concrete, concrete masonry unit blocks, or rockeries. Alternatively, these walls can consist of reinforced soil and block-facing structures typically referred to as MSE walls. In recent years, the latter structural system has proven to be an economically reasonable alternative to more traditional retaining wall systems. Because there are many proprietary MSE structure types available, it is typical for the wall provider to complete the design analysis for the wall that will be installed. The parameters given above for earth pressures and sliding resistance can also be used for design of MSE walls. These (m0ESIGNi II KCHA-29-03:021814 DRAFT walls typically have reinforcement embedment lengths of approximately 80 percent of the height of the wall. Minimum embedment depth for MSE walls is 2 feet. We can provide additional design considerations for rockeries, if requested. Care should be taken by the contractor during backfilling of retaining walls to avoid overstressing the walls. Backfill placed within approximately S feet of the walls should be compacted with hand-operated or small self-propelled equipment. Heavy compactors or other heavy construction equipment should not be used within approximately S feet of the walls. 6.6 STORMWATER INFILTRATION EVALUATION We anticipate that the bottom of the infiltration pond will be approximately 12 feet BGS. Soil conditions at the base are expected to be sandy silt interbedded with silty sand. Infiltration characteristics of the soil within the project area were evaluated through grain-size distribution tests and in situ testing using the falling head test procedure. The locations of the infiltration tests were selected to correspond with the proposed location of the infiltration pond. All ofthe tests were conducted in general accordance with the EPA falling head percolation test procedure. The tests were conducted at a depth of approximately 1 2 feet BGS near the anticipated base of the pond. The infiltration rate determined using falling head test methodology is a short-term infiltration rate. A correction factor is necessary to account for the small scale of the test and other factors in order to estimate the long-term design infiltration rate from the test. Additional corrections to the measured infiltration rate are necessary to account for testing uncertainties, depth to the water table or nearest impervious layer, geometry of the infiltration receptor, and long-term reduction in permeability due to biological activity and accumulation of fines. The recommended correction factors to be applied to the "short-term" rate measured in the tests are summarized as follows: • Correction factor F accounts for uncertainties in testing methods. A correction factor of ,mmg 0.3 is required by the King County 2009 SWDM for the EPA falling head percolation test. • Correction factor F accounts for the influence of the facility geometry and depth to the -water table or impervious strata on the actual infiltration rate. A shallow water table or impervious layer will reduce the infiltration rate and will not be reflected in a small-scale test like the EPA falling head test. The correction factor is determined by the width of the proposed infiltration facility and the depth from the bottom of the proposed facility to the highest water table level or the nearest impervious layer, whichever is less. We recommend a correction factor F..,,..,, of 0.55. • Correction factor F accounts for reduction in infiltration rates over the long term due to ~ ...... the plugging of soil. The correction facto( varies between 0.7 for loams and sandy loams to 1 .0 for coarse sand or cobbles. The site is underlain by fine-grained material that would be classified as loams or sandy loams, and a correction factor of 0. 7 is recommended. 12 KCHA-29-03:021814 DRAFT The "long-term design infiltration rate" is determined by multiplying the measured rate by the recommended correction factors, which are equivalent to a combined correction factor of 0.12. Table 3 summarizes the infiltration test results along with the correction factor. Table 3. Soil Infiltration Rate Analysis' Infiltration Measured Long-Term Design Point Infiltration Rate Infiltration Rate' (inches per hour) (inches per hour) B-5 4.6 0.55 B-6 5.2 0.62 B-7 2.2 0.26 l. For selected soil samples and test locations 2. Based on the recommended combined correction factor of 0.18 In accordance with King County 2009 SWDM Stormwater infiltration will vary across the site due to the variability of the fine-grained alluvium underlying the surficial fill material. We recommend an overall long-term design infiltration rate of 0.4 inch per hour for design of the infiltration pond. 6.6.1 Soil Suitability for Treatment The soil below the planned base of the infiltration pond meets the King County 2009 SWDM for water quality treatment outside of groundwater protection areas. Infiltration will be controlled by the fine-grained layers composed of sandy silt and silt. A CEC of at least 5 meq per 100 grams and a minimum organic content of 0.5 percent are required for water quality treatment (King County SWDM, 2009). Test results indicate that the CEC ranges between 7.4 and 8.6 meq per 1 00 grams for the samples collected within 2 or 3 feet of the base of the pond, approximately 15 feet BGS, which meets the minimum criteria for treatment. Organic matter content of the soil ranges between 0.6 and 0.9 percent in tested samples, which is greater than 0.5 percent minimum requirement per the design manual. 6.7 PAVEMENT DESIGN 6.7.1 General We understand that both traditional HMA and pervious HMA pavements are planned for this project. Traditional HMA pavement will be used to construct the access driveways and the drive aisles in the parking areas. Pervious HMA will be used in the parking stall areas. In addition, a perimeter emergency access road around the west and south sides of the main building will be surfaced with Grasscrete. Parking areas will be subject to light automobile traffic. Access driveways will be subject to moderate traffic loading from light delivery trucks and moderately heavy garbage trucks. The Grasscrete road will be subject to light loads from maintenance vehicles and moderately heavy fire-fighting apparatus if needed. We understand that the concrete sidewalk area adjacent to the Grasscrete road will also be designed for moderately heavy fire-fighting apparatus loads. DDESIGN2 13 KCHA-29-03:021814 DRAFT 6.7.2 Traditional HMA Pavement The traditional HMA should be HMA Class Y,-inch PG 64-22, with aggregate, gradation, and asphalt requirements in accordance with WSS Section 9-03.8(6) -HMA Proportions of Materials. This HMA should be compacted to 91 percent of the maximum specific gravity of the mix, as determined by ASTM D 2041. Minimum lift thickness for Y,-inch HMA is l .5 inches. Asphalt binder should be performance graded and conform to PG 64-22. The aggregate base material should meet the specifications for aggregate base rock provided in the "Structural Fill" section of this report. The subgrade should be compacted to at least 95 percent ofthe maximum dry density, as determined by ASTM D l 557. 6-7.Z.1 Access Roadway We recommend a pavement section consisting of 3 inches of HMA over 6 inches of l 14-inch- minus crushed rock in accordance with WSS 9-03.9(3) -Crushed Surfacing Base Course. Alternatively, an applicable pavement section using ATB would consist of 4 inches of ATB and 4 inches of base course. 6. 7.Z.Z Parking Area Drive Aisles For the drive aisles in areas limited to automobile traffic only, we recommend a pavement section consisting of 2.5 inches of HMA over 4 inches of 114-inch-minus crushed rock in accordance with WSS 9-03.9(3) -Crushed Surfacing Base Course. Alternatively, an applicable section using ATB would consist of 3 inches of ATB and 2.5 inches of base course. 6.7.3 Pervious HMA Pervious pavement is constructed of different materials and layer thicknesses than traditional HMA pavement. To promote infiltration through the HMA layer, more open-graded aggregate is used in the HMA mix and a different binder grade may be used. To provide water storage the crushed base material below the HMA is thicker and also more open-graded than the base course recommended by WSS. To help reduce penetration of the HMA into the open-graded water storage material, a thin choker layer is placed between the water storage material and the HMA. Similarly, a geotextile fabric is placed on the native subgrade soil to help prevent penetration of the subgrade soil into the water storage layer. HMA used for pervious asphalt pavement should be designed as a Y,-inch nominal, open-graded HMA. Selection of the preferred aggregate size should be based on the desired surface texture and the required layer thickness limitations. A recommended aggregate gradation for pervious asphalt is provided in Table 4. DDESIGN2 14 KCHA-29-03:021814 DRAFT Table 4. Pervious HMA Gradation (Y.z inch) Sieve Size Yz Inch Percent Passing 1-inch %-inch 99 -100 1 /2-inch 90-98 3/8-inch #4 18 -32 #8 3 -15 #200 0-3 Recommended Layer Thickness 3 (inches) Asphalt binders to construct pervious asphalt pavement include PG 64-22 and PG 70-22. The preferred and recommended asphalt binder is PG 70-22ER (polymer modified); however, its availability can be limited because some of the local asphalt suppliers limit their on-hand binder to PG 64-22. PG 70-22ER is available but is typically stocked by asphalt suppliers for a specific project, which requires pre-ordering it so that it is available when needed. Suppliers prefer a project size of approximately 600 tons of asphalt in order to utilize a complete tanker volume of the binder. The availability and use of PG 70-22ER is further restricted to the warm months of the year because of its stiffness, so it is not readily available between October and May. Projects specifying PG 70-22ER should be scheduled accordingly and specifications should address supplier availability. The binder should be between 5.5 and 6 percent of the pavement section by weight. Compaction of the pervious HMA should consist of approximately two to four complete passes by an 8-ton, dual, steel roller compactor working in static mode only. 6. 7.3. 1 Pervious Pavement Subgrade Preparation The subgrade for pervious pavements should be relatively flat (less than 3 percent slope) to prevent uneven ponding of water within the storage aggregate. The exposed subgrade should be proofrolled with a fully loaded dump truck or similar heavy, rubber-tire construction equipment to identify soft, loose, or unsuitable areas. If areas of excessive yielding are identified, the material should be excavated and replaced with water storage aggregate. The subgrade should be compacted to a maximum of 92 percent of the maximum dry density, as determined by ASTM D 1557. 15 KOIA-29·03:021814 DRAFT Exposed subgrades will be moisture sensitive and will deteriorate under construction traffic loading under wet conditions. If earthwork construction is expected to extend into the wet season, we recommend limiting the size of the work area and stabilizing the exposed surface by placing the water storage aggregate to protect the subgrade. Construction traffic should be kept off of the pervious pavement subgrade. 6.7.3.2 Subgrade Geotextile A layer of geotextile fabric should be placed as a barrier between the native soil subgrade and the water storage aggregate. The geotextile should be non-woven and conform to the specifications for Class A, underground drainage material provided in WSS 9-33.2(1) -Geotextile Properties, Table 2 Geotextile for Underground Drainage. The geotextile should be installed in conformance with the specifications provided in WSS 2-1 2 -Construction Geosynthetic. 6. 7.3.3 Pervious Pavement Water Storage Aggregate We recommend that the water storage aggregate layer be 1 2 inches thick. Imported granular material used as water storage aggregate beneath pervious pavements should be clean crushed rock or crushed gravel and sand that meets the criteria ofWSS 9-03.9(2) -Permeable Ballast. Recommended gradations for acceptable storage aggregate are provided in Table 5. Table 5. Pervious Pavement Water Storage Aggregate wss Sieve Size Permeable Ballast Percent Passing 2Y, inches 90 -100 2 inches 65 -100 1 Y, inches l inch 40 -80 % inch Y, inch No.4 0·5 No. 100 0-2 Percent Fracture 75 The storage aggregate should be placed in one lift and be compacted to a firm condition. Over compaction and construction traffic should be avoided. 6.7.3.4 Pervious Pavement Choker Aggregate Imported granular material used as choker aggregate beneath pervious pavements should be clean crushed rock that meets the criteria ofWSS 9-03.9(3) -Crushed Surfacing Top Course. 6.7.3.5 Pervious Pavement Considerations We recommend the following considerations for installation of pervious pavement: 16 KCHA-29·03:021814 DRAFT • The long-term performance of pervious pavements is reliant upon proper design, installation, and long-term maintenance. Although design life of pervious asphalt pavement installations in parking areas is commonly indicated to be greater than 20 years, we recommend an assumed pavement design life of between 15 to 20 years. • Consideration should be given to limiting the use of pervious pavement to the parking strip and sidewalk areas, while still constructing a water storage aggregate layer beneath the entire roadway. Run-off from the entire roadway can be infiltrated through the parking strip area and into the storage aggregate while reducing construction and long-term maintenance costs. Contributory non-pervious areas to pervious areas should not be more than two times the size of the pervious area. • Consideration should also be given to limiting the thickness of single layer pervious asphalt pavement to a maximum thickness of 4 inches. Sections thicker than 4 inches should be constructed using a layer of asphalt-treated pervious base below the pervious asphalt. • Sediment, organic debris, and bio-mass growth will reduce the permeability of pervious pavement. Regular periodic maintenance is required to maintain the hydrologic performance of the pavement. Maintenance should consist of periodic cleaning by regentative air sweeping and/or vacuum sweeping and flushing with high volume water at low pressure. Based on available information, vacuum sweeping should be performed two to four times per year and flushing at least once per year. • Sanding for snow and ice removal should be avoided on pervious pavement. • Public awareness plans should be developed to educate residents on activities that should be avoided on or adjacent to pervious pavement. • During and after construction, stockpiles of landscaping materials (e.g., topsoil, bark dust, etc.) and construction materials (e.g., sand, gravel, etc.) should not be placed on the pervious pavements. Extreme care should be taken to prevent trafficking of muddy construction equipment over pervious pavements. • Landscaping areas that are adjacent to pervious pavements should be sloped or bermed to prevent run-off from washing debris onto the pavement and designed such that leaf debris does not accumulate on the pavement. These recommendations are based on general assumptions regarding anticipated traffic and assume adequate subgrade and drainage conditions. Pavement materials and placement should conform to WSS. 6.7.4 Grasscrete Pavement Grasscrete pavement is proposed for use to surface an access roadway that will be located around the rear of the future multi-family building complex. The pavement will provide emergency access to the rear of the building complex as well as for building and site maintenance equipment. t11i'lDESIGN2 17 KOiA-29-03:021814 DRAFT Grasscrete consists of reinforced concrete that is cast within a plastic cellular "former." The formers are available in several configurations and thicknesses to accommodate different vehicle loads. The concrete is underlain by coarse, open-graded gravel for support and load distribution as in traditional pavement sections. Once the concrete is cured, the exposed former surface is melted away and the internal open spaces are filled with topsoil that is subsequently seeded. The Grasscrete pavement is to be designed to support fire-fighting apparatus. Information from the City of Renton Fire Department indicates that the design fire-fighting apparatus weighs 72 kips (20-kip front and 52-kip rear axles) and utilizes outriggers that impose loads of up to 50.7 kips on pads that measure 26 inches by 26 inches. Grasscrete is a proprietary product manufactured by Grass Concrete Limited of the United Kingdom. We were provided product information for Grasscrete that included an installation brochure titled "Grasscrete, Cast lnsitu Paving System" as well as a link to a web site that contained design information for the Grasscrete product (http://www.grasscrete.com/pdfs/GrasscreteBrochure.pdfl. We also reviewed other design information linked to the product site at www.grasscrete.com. Based on our review of the available Grasscrete produce information, the Grasscrete pavement appears to be capable of supporting the design fire-fighting apparatus loads. The information is given in the metric 51 system. The equivalent fire apparatus weight is 33 tonnes (1 metric tonne equals 2,205 pounds). For this vehicle weight, the following Grasscrete pavement section is recommended: • CG2 or CG2sc formers measuring 1 50 millimeters thick (5.9 inches) should be used. The concrete reinforcement should consist of A393 welded-wire mesh. To promote infiltration through the Grasscrete surface, it is underlain by open-graded water storage aggregate that is covered by a thin choker layer and underlain by a geotextile fabric placed on the prepared native subgrade. We recommend that the aggregate layer be 12 inches thick and consist of clean crushed rock or crushed gravel and sand that meets the criteria of WSS 9-03.9(2) - Permeable Ballast. The choker layer should be 1 inch thick and meet the criteria of WSS 9-03.9(3) -Crushed Surfacing Top Course. The subgrade geotextile should be non- woven and conform to the specifications for Class A, underground drainage material provided in WSS 9-33.2(1) -Geotextile Properties, Table 2 Geotextile for Underground Drainage. The aggregate layer should be placed in one lift and compacted to a firm condition. Over compaction and construction traffic should be avoided. Expansion joints within the pavement surface, edging details, concrete placement protocol, and other installation products and details should be consistent with the recommendations of the Grasscrete product manufacturer. We recommend that the contractor who installs the Grasscrete pavement have experience with this product and installation protocol. We also recommend that the Grasscrete manufacturer's representative review and approve this application and the selected installation contractor. 18 KCHA-29-03:021814 DRAFT The Grasscrete product relies on a soil subgrade with a bearing capacity of 45 kN/m'(900 psf). In our opinion, the subgrade bearing capacity will exceed this requirement provided that it is properly prepared. The subgrade should be relatively flat (less than 3 percent slope) to prevent uneven ponding of water within the storage aggregate. The exposed subgrade should be proofrolled with a fully loaded dump truck or similar heavy, rubber-tire construction equipment to identify soft, loose, or unsuitable areas. If areas of excessive yielding are identified, the material should be excavated and replaced with water storage aggregate. The subgrade should be compacted to a maximum of 92 percent of the maximum dry density, as determined by ASTM D 1557. Exposed subgrades will be moisture sensitive and will deteriorate under construction traffic loading under wet conditions. If earthwork construction is expected to extend into the wet season, we recommend limiting the size ofthe work area and stabilizing the exposed surface by placing the water storage aggregate to protect the subgrade. Construction traffic should be kept off of the Grasscrete subgrade. We understand that the 5-foot-wide sidewalk that is immediately adjacent to the Grasscrete access road is also considered to be part of the fire access road and needs to support the loads of the fire equipment. To accomplish this, we recommend upgrading the sidewalk section thicknesses to be essentially equal to the Grasscrete section thicknesses. We recommend the sidewalk section consist of a 6-inch-thick concrete surface, over a 1-inch- thick choker layer of Crushed Surfacing Top Course [WSS 9-03.9(3)], over a 12-inch-thick aggregate layer of Permeable Ballast [WSS 9-03.9(2)], with a geotextile between the ballast and the prepared subgrade. The geotextile should be Class A, underground drainage material provided in WSS 9-33.2(1) -Geotextile Properties, Table 2 Geotextile for Underground Drainage. The same subgrade and material placement recommendations that were presented above for the Grasscrete area should be used for the sidewalk area. Because the sidewalk is immediately adjacent to the Grasscrete, using the same material thicknesses will facilitate construction of both pavement areas. Sidewalks that are outside the 20-foot-wide fire access area can be conventional section thicknesses. 7.0 SEWER IN STEEP SLOPE AREA 7.1 SLOPE TOPOGRAPHY The vertical height of the slope that the sewer will descend is approximately 3 5 feet along the trend of the pipe alignment. The slope is inclined at 2H:l V. However, the sewer will descend the slope on a slight skew; therefore, the slope inclination along the sewer alignment is slightly less than 2H:1V. The slope was constructed as a fill and the face of the slope is relatively uniform. The slope is vegetated with grass, brush, and trees. Surface water or groundwater seepage was not observed along the pipe alignment or elsewhere on the slope at the time of our visit. 19 KCHA-29·03:021814 DRAFT 7.2 SUBSURFACE SOILS The soils encountered in the boring nearest to the sewer alignment (B-3) encountered stiff silt fill and loose, silty sand to a depth of 4.5 feet BGS. The loose sand is underlain by dense sand to 40.5 feet, the maximum depth of the boring. No groundwater was noted in this boring. Based on our observations and experience, it is our opinion that the surficial soils are generally stable and retained by the vegetation on the face of the slope. However, surficial soils on a steep slope are susceptible to downslope movement via raveling and soil creep. Raveling is caused by surface water sheet wash and rilling. Soil creep is generally shallow downslope movement of the upper weathered soil layer (colluvium). The movement generally extends a few feet below the ground surface and often occurs without a well-developed failure surface. Soil creep is often evidenced by bowed tree trunks and leaning or downed trees. The rate of soil creep may be increased by erosion undercutting of the slope or by man-made excavations that over-steepen the slope. Soil creep can also be aggravated by water accumulation. 7.3 SEWER PIPELINE RECOMMENDATIONS We recommend that the sewer pipeline down the slope be completed in a trench to protect the pipeline and to place the pipe below the surficial soils on the face of the slope. The surficial soils are subject to downslope creep due to weathering and erosion and are, therefore, not suitable to support the pipeline. Recommendations for the pipeline construction in the slope area are presented in the following sections of this report. 7.3.1 Site Preparation We recommend that disturbance to the slope surface be minimized. Removal of vegetation and surficial root zone soil should be limited to the immediate vicinity of the trench. The soils on the slope are susceptible to disturbance from equipment and foot traffic. We recommend that construction be performed during periods of extended dry weather to reduce the impacts of stormwater runoff. 7.32 Pipe Construction We understand that the sewer will consist of ductile iron pipe with restrained joints. We recommend that the pipeline be anchored to the manhole at the upper end of the pipeline to provide additional restraint. All temporary cut slopes and shoring must comply with the provisions of Title 296 WAC, Part N, "Excavation, Trenching and Shoring." The contractor performing the work must have the primary responsibility for protection of workmen and adjacent improvements, deciding whether or not to use shoring, and for establishing the safe inclination for open-cut slopes. Temporary unsupported cut slopes more than 4 feet high may be inclined at l l1.H: l V maximum steepness. Flatter slopes may be necessary if seepage is present on the cut face. Some sloughing and raveling of the cut slopes should be expected. Temporary covering with heavy plastic sheeting should be used to protect these slopes during periods of wet weather. [iffll0ES1GN1 20 KCHA-29-03:021814 DRAFT Excavations could encounter seepage, especially in the areas where silty materials are present in the slope. We expect that seepage in excavations can be handled by using sump pumps. The pump discharge hoses should be extended to the bottom of the slope so that water is not discharged onto the slope. 7.3.3 Pipe Burial Depth We recommend that a minimum pipe burial depth of 4 feet be used over the crown of the pipe. This minimum burial depth should be measured from the existing slope surface. The purpose of the minimum cover depth is to position the pipe below the zone of potential surficial instability on the slope. 7.3A Pipe Bedding We recommend that bedding consist of sand and smooth, rounded gravel such as specified in WSS 9-031 5 -Native Material for Trench Backfill. The bedding material should extend to 1 foot above the pipe. 7.3.5 Anchor Blocks We recommend that the pipe be restrained with anchor blocks spaced every 50 feet along the pipeline through the steep segment of the sewer. The anchors should consist of blocks of concrete that completely surround the sewer pipe and that are keyed into the native material at least 12 inches on the sides and bottom of the trench. The concrete should also extend at least 12 inches above the pipe. The anchor blocks should be a minimum of 18 inches wide. The sewer pipe should be sleeved through the anchor blocks with an oversized pipe segment to prevent abrasion of the sewer pipe from contact with the concrete. As discussed below, we recommend that the pipe anchors be penetrated with a perforated pipe to facilitate drainage of the beddiog material where silty soils are present along the sewer trench. We understand that this sewer pipeline facility will become the property of Soos Creek Water and Sewer District. Typical details for pipe anchor blocks are presented in the Soos Creek Water and Sewer District Standard Plans. We recommend that the Soos Creek Water and Sewer District Standard Plan anchor blocks be modified to conform to the recommendations presented above. 7.3.6 Thrust Blocks Thrust blocks used to resist lateral pipe loads may be designed using an allowable passive lateral resistance corresponding to an equivalent fluid density of 300 pcf, measured from the ground surface. An allowable frictional resistance of 0.35 between the concrete and dense native soil may be used in conjunction with passive resistance. Where the pipe alignment results in a downward thrust load on the soil, an allowable bearing value of 2,000 psf may be used for design ofthrust blocks supported on dense native soil. 7.3.7 Trench Drains Because the majority of the native soils in the slope are relatively free-draining, water accumulation within the trench backfill should not be a concern along most of the steep hill area. RDESIGNi 21 KCHA-29-03:021814 DRAFT However, water could accumulate within the trench backfill in the areas where silty soils are present. The pipe bedding will tend to convey seepage along the trench in these areas. Where silty soils are present along the sewer trench, we recommend that the pipe anchors be penetrated through with minimum 4-inch-diameter perforated pipe, installed near the bottom of the pipe bedding horizon. The perforated pipes will allow any accumulated seepage in the sewer pipe bedding to pass through the pipe anchors. We recommend not penetrating the pipe anchors with perforated pipe in areas where relatively free-draining material is present along the sewer pipe. We recommend that the perforated pipe be smooth-wall rigid pipe (SDR-35) or ADS N-12 corrugated pipe. The pipe should have two rows of perforations, and the perforations should be installed pointing downward. The perforated pipes should extend to the base of the slope and be discharged to the ground surface at an appropriate location. The end of the pipe at the discharge location should be covered with heavy galvanized wire mesh to prevent rodents from entering the pipe. 7.3.8 Backfill Backfill placed above the pipe bedding material should consist of the native soil excavated from the trench or structural fill imported to the site. Structural fill material should be free of debris, organic contaminants, or rock fragments larger than 3 inches. We recommend that imported structural fill material have no more than approximately 5 percent fines. Trench backfill on the slope should be compacted to a minimum of 90 percent of the maximum dry density, in accordance with the ASTM D 1557 test procedure. 7.4 EROSION PROTECTION Temporary erosion protection should be placed and maintained during construction to protect the slope surface. We recommend use of straw, jute matting, or equal as temporary erosion protection. Following completion of the pipeline construction, the slope surface should be restored and protected from erosion, and the vegetation should be re-established. The slope surface should be mounded up slightly over the sewer pipe trench so that surface runoff does not become channeled and flow along the sewer alignment. We recommend that organic soil or surface strippings be spread over the prepared slope surface approximately 3 inches thick to promote re-vegetation. The surface soil should be tamped in place with lightweight, hand-operated compaction equipment or track-walked with a small dozer operating up and down the slope to achieve a moderate degree of compaction and a texture appropriate for seeding. The disturbed slope area should be covered with an erosion mat to protect the surface until the vegetation is established. Erosion mats are available with jute, straw, excelsior, and coconut fibers; any of these can be used. The mat should be placed and stapled as recommended by the manufacturer. •DESIGN:' 22 KOiA-29·03:021814 DRAFT Application of the re-vegetation seeding may precede or follow placement of the erosion mat, as recommended by the manufacturer. We suggest that the re-vegetation seed mix be selected by an experienced landscape professional. The seed mix must consider the time of year for application, the steepness and direction of the slope, the available light, and soil conditions. No irrigation should be planned. Maintenance and reseeding as necessary must be anticipated until the vegetation is well established. 8.0 SITE DEVELOPMENT 8. 1 SITE PREPARATION The proposed building locations and associated hardscape areas are within an open field with a slope grading upward towards the west and south that is landscaped with grass. Site preparation will generally include stripping and subgrade preparation to prepare the site for grading or fill placement in order to establish the required ground surface elevations. These activities will include removal of vegetation and undesirable material, including stripping of topsoil, subgrade preparation, and site grading. Recommendations for these activities are discussed below. 8.1.1 Stripping and Grubbing Stripping and grubbing should include the removal of vegetation, organic material, and man- made debris. Based on the explorations, the organic material (roots and wood debris) generally extends to a depth of 6 inches. The actual stripping depth should be evaluated based on observations made during construction. Stripped material should be transported off site for disposal or used as fill in landscaping areas, provided it meets the requirements for common fill. 8.12 Subgrade Preparation After demolition and removal of surficial organic matter, site grading should be completed to the required elevations. Based on the results of our explorations, we anticipate that unengineered fill consisting of silty sand and sandy silt will be exposed at subgrade elevations over most of the site. Over-excavation and replacement of the unengineered fill will be required beneath foundation elements as described in the "Foundation Support -Shallow Spread Footings" of this report. Beneath floor slab and hardscaped areas, over-excavation and subgrade preparation should be consistent with that described in the "Concrete Slab on Grade" section of this report. The exposed subgrade outside of the building area in hardscape areas should be scarified to a depth of 12 inches, moisture conditioned, and compacted to a dense and unyielding condition. Soil moisture should be maintained within 2 percent of the optimum moisture content to achieve the required compaction. Following compaction of the subgrade, the exposed surface should be proofrolled with a fully loaded dump truck or similar heavy, rubber-tire construction equipment in the floor slab and 23 KCHA-29-03:021814 DRAFT paved areas to identify soft, loose, or unsuitable areas. If soft or loose zones are identified, these areas should be excavated to the extent indicated by the engineer or technician and replaced with structural fill or stabilization material. It should be recognized that the exposed subgrade will consist of silty sand and sandy silt with a high fines content. The subgrade will be moisture sensitive and will deteriorate under construction traffic loading during wet weather. If earthwork construction is expected to extend into the wet season, we recommend stabilizing the improved areas by either over-excavating the area and constructing a 12-inch-thick gravel pad or stabilizing with cement-amended soil overlain by 4 inches of crushed rock. 8.1.3 Site Grading Fill required to raise site grades in improved areas should consist of structural fill as described in the "Fill Materials" section of this report. The use of on-site excavation spoils as structural fill will be dependent on the material composition and weather conditions. We anticipate that some of the on-site material will be suitable for use but will be limited to use during the dry season, provided deleterious material (such as wood debris, organics, and man-made material) is removed. It will be prudent to provide an 18-inch-thick cap of imported structural fill over areas where on-site soil is used as fill to protect it against deterioration during wet weather. Fill required to backfill over-excavations beneath foundation elements and floor slabs should consist of imported stabilization material placed and compacted as recommended in the "Fill Materials" section of this report. Fill in unimproved areas, with slopes less than 3H:1V, may consist of common fill or on-site excavation spoils, provided deleterious material (such as man-made material and large, woody debris) is removed. Common fill placed in landscape of unimproved areas should be placed in lifts with a maximum uncompacted thickness of 8 to 12 inches and compacted to not less than 90 percent of the maximum dry density, as determined by ASTM D 1557. 8.1.4 Temporary and Permanent Slopes We recommend that temporary slopes for construction of underground utilities and basement excavations be inclined no steeper than 1 YzH: 1 V. Steeper utility or basement excavations will need to be supported by shoring. Permanent slopes should be inclined no steeper than 2H: 1 V. 8.1.5 Subgrade Evaluation Exposed subgrades should be observed by a representative from GeoDesign to evaluate whether the conditions are as anticipated and will provide the required support. Where pavement or hardscaped areas will be constructed, the exposed subgrade should be evaluated by proofrolling. Beneath foundations and during wet weather, subgrade evaluation should be performed by probing with a hand probe. 8.1.6 Surface Drainage All ground surfaces, pavements, and sidewalks should be sloped away from the structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or RDESIGN1 24 KCHA-29-03:021 814 DRAFT catch basins and conveyed to appropriate discharge points. Roof drains from structures should be tightlined to discharge into the stormwater collection system. Surface water should not be discharged into subdrains or wall backdrains. 8.2 EXCAVATION 8.2.1 Shallow Excavation The soil at the site can be excavated with conventional earthwork equipment. Excavations should stand vertical to a depth of approximately 4 feet, provided groundwater seepage is not observed in the trench walls. Open excavation techniques may be used to excavate utility trenches with depths greater than 4 feet, provided the walls of the excavation are cut at appropriate cut slopes determined by the contractor. Approved temporary shoring is recommended where sloping is not possible. If a conventional shield is used, the contractor should limit the length of open trench. If shoring is used, we recommend that the type and design of the shoring system be the responsibility of the contractor, who is in the best position to choose a system that fits the overall plan of operation and the subsurface conditions. All excavations should be made in accordance with applicable OSHA, local, and state regulations. Open excavation techniques may be used for temporary excavations for basements, provided that there is space to slope the walls. We recommend a slope of 1 l1zH:1V where space is allowed; if space does not permit, approved temporary shoring is recommended. 8.22 Excavation Dewatering We do not anticipate significant groundwater will be encountered in excavations. We recommend that the contractor be responsible for selecting the appropriate temporary dewatering systems. 8.3 FILL MATERIALS We anticipate fill material will be required for site grading, backfilling over-excavations, pavement support, installation of utilities, and drainage. The recommended fill materials are discussed below. 8.3.1 On-Site Soi I Fill was encountered to depths of approximately 13 feet BGS in the southwest section of the site and to 1 foot in the northwest section of the site. The fill is characterized by a high fines content, is sensitive to changes in moisture content, and will deteriorate when exposed to wet weather. We recommend against prospective bidders assuming that all of the on-site excavation spoils can be used as structural fill. We anticipate that some of the excavation spoils can be used as structural fill, provided construction is completed during the dry season, moisture conditioning is performed, and deleterious material (such as wood, organics, and man-made materials) are removed. The use of on-site soil as fill should be subject to review and approval by GeoDesign. RDESIGN:! 25 KCHA-29-03:021814 DRAFT The on-site material free of man-made materials and/or large, woody debris may be used in non- structural areas, such as planter areas or unimproved areas. Laboratory testing indicates the moisture content of on-site soil ranges between 5 and 7 percent. Based on our experience with similar soil, the optimum moisture content is approximately 8 to l 2 percent. Moderate moisture conditioning efforts of the on-site soil will be required in order to achieve proper compaction. 8.32 Off-Site Recycled Fill Material Off-site generated recycled material should not be used on site without approval from the geotechnical engineer and acceptance by KCHA. The use of recycled material will be subject to performance criteria, gradation requirements, and hazardous material testing in conformance with WSS 9-03.21 (l) -General Requirements. Recycled material is not recommended for use beneath building foundations or floor slabs. Provided performance, gradation, and hazardous material testing results are acceptable, recycled material consisting of recycled concrete may be suitable for use beneath hardscape areas outside of the building footprint. 8.33 Structural Fill Structural fill placed for general site grading in improved areas should consist of clean, free-draining granular soil (sand and gravel) that is free from organic matter or other deleterious and man-made material, with a maximum particle size of approximately 3 inches and a maximum fines content of 5 percent by dry weight. The use of granular free-draining material will increase the workability of the material during the wet season and the likelihood that the material can be placed and adequately compacted. Imported granular material used for structural fill should be naturally occurring pit-or quarry-run rock, crushed rock, or crushed gravel and sand and should meet the specifications provided in WSS 9-03.14(1) -Gravel Borrow, with the exception that the percentage passing the U.S. Standard No. 200 Sieve does not exceed 5 percent by dry weight. Structural fill should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 8.3.4 Common Fill Fill placed in areas of the site where structural support is not required (such as planters, landscaped areas, and detention ponds) is defined as "common fill." Common fill may contain a higher concentration of fines and organic matter than structural fill but should be free of man-made material. Imported common fill should meet the specifications provided in WSS 9-03.14(3) -Common Borrow. On-site material used for common fill should have an organic matter content less than 20 percent. Fill placed in non-structural areas should be compacted to a minimum of90 percent of the maximum dry density, as determined by ASTM D 1557. 8.3.5 Hardscape and Pavement Base Course Imported granular material used as aggregate base for pavements and beneath hardscape areas should consist of l Yz-inch-minus material meeting the specifications provided in WSS 9-03.9(3) - Crushed Surfacing Base Course, with the exception that the aggregate should have less than 5 percent by dry weight passing the U.S. Standard No. 200 Sieve and at least two mechanically BDESIGNr 26 KCHA-29·03:021814 fractured faces. The imported granular material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 8.3.6 Trench Backfill DRAFT Trench backfill for utility trenches should consist of and be compacted in accordance with the specifications for structural fill in improved areas and for common fill in non-structural areas. Trenches within the right-of-way should be bedded and backfilled with 5/8-inch-minus crushed rock meeting the specifications provided in WSS 9-03.9(3) -Crushed Surfacing Top Course. 8.3.7 Stabilization Material Stabilization material to backfill excavations beneath foundations or soft subgrade areas should consist of permeable ballast and should meet the specifications provided in WSS 9-03.9(2) - Permeable Ballast. Stabilization material used to fill over-excavations should be placed in 12-inch-thick lifts and compacted to a dense, unyielding condition. 8.3.8 Free-Draining Material Free draining material used in footing drains and in wall backdrains should consist of granular material that meets the specifications provided in WSS 9-03.12(2) -Gravel Backfill for Walls. 8.3-9 Underslab Drainage Gravel The underslab drainage gravel should consist of l ¥..-inch-minus clean crushed gravel with negligible sand or silt (WS~ 9-03.1 (4)C-Grading, No. 57). The imported granular material should be placed in one lift and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. 8.3.1 0 Water Storage Aggregate Material used for water storage aggregate in pervious HMA pavement and in the Grasscrete pavement should consist of permeable ballast meeting the specifications provided in WSS 9-03.9(2) -Permeable Ballast. 8.4 GEOSYNTHETICS If any geotextiles are used on this project, the geotextiles should be installed in conformance with the specifications provided in WSS 2-12 -Construction Geosynthetic. 8.4.1 Stabilization Geotextile If construction extends into the wet season, stabilization fabric should also be placed in paved areas between the exposed subgrade and granular fill or base course. The geotextile should conform to the specifications for woven soil stabilization material provided in WSS 9-33.2(1) - Geotextile Properties, Table 3 Geotextile for Separation or Soil Stabilization. 8.4.2 Separation and Drainage Geotextile We recommend using a non-woven geotextile material below the slab-on-grade gravel base layer and the water storage aggregate in the pervious HMA pavement and the Grasscrete pavement. The geotextile should conform to the specifications for non-woven separation material 27 KCHA-29-03:021814 DRAFT conforming to the specifications for Class A, underground drainage material provided in WSS 9- 33.2(1) -Geotextile Properties, Table 2 Geotextile for Underground Drainage. 8.5 CONSTRUCTION STORMWATER CONSIDERATIONS The site is located at the top of a ravine, and surrounding areas on the south and east drain towards the site. Grading during construction should be completed to convey surface water away from construction areas. The soil encountered on site is high in silt, which will be difficult to remove from stormwater using passive systems, such as sediment traps and ponds. 8.6 WET WEATHER CONSIDERATIONS This section describes additional recommendations with potential budget and schedule impacts that may affect the owner and site contractor if earthwork occurs during the wet season. These recommendations are based on the site conditions and our experience on previous construction projects completed in the area. • The fill encountered in the explorations is typically silty sand and sandy silt. The fines content of this material is high, and the soil will be susceptible to deterioration during wet weather. Material below the fill is lower in fines content and will be less susceptible to deterioration during wet weather. If construction is completed or extends into the wet season, we recommend stabilizing the areas of the site where construction traffic is anticipated using either a gravel working pad or cement-treated soil overlain with a 4-inch layer of crushed rock. Additional Best Management Practices will be necessary in cement- treated areas and to monitor/manage the pH levels in stormwater discharge. • Site soil will not be suitable for use as structural fill during wet weather and imported fill will be required. Imported fill will need to consist of non-moisture sensitive material composed of sand and gravel or crushed rock material. • Earthwork should be accomplished in small sections to minimize exposure to wet weather. • Excavation or the removal of unsuitable soil should be followed promptly by the placement and compaction of clean structural fill. • The size of construction equipment and access to the area should be limited to prevent soil disturbance. • The ground surface in the construction area should be sloped and sealed with a smooth-drum roller to promote rapid runoff of precipitation, to prevent surface water from flowing into excavations, and to prevent puddles from forming. • The building pads should be surfaced with a 12-inch-thick gravel pad consisting of stabilization material as described in the "Fill Materials" section of this report. This layer will help protect the pad from deterioration under construction traffic during wet weather. The DDESIGN;i 28 KOiA-29·03:021814 DRAFT protected area should also extend outwards from the building pad a sufficient distance to provide stabilized access for construction equipment around the perimeter of the building. • Additional excavation below planned foundation subgrades should be anticipated in order to construct a 2-inch-thick lean mix concrete rat slab or to install a 6-inch-thick layer of crushed surfacing base course to protect the foundation subgrade from deterioration. • Installation of sumps within excavations may be necessary to remove accumulated stormwater. The sumps should be located outside of the footing footprint and installed to a depth sufficient to lower the water to below the excavated subgrade elevation. • Construction of stabilized access roads using non-moisture sensitive material and geotextile fabric to provide separation from underlying soil should be expected. • Increased handling, excavation, and disposal of wet, disturbed surface material should be expected. • Protection of exposed soil subgrades and stockpiles will be required. • Heavy rainfall can occur during winter months and can compromise earthwork schedules in this region. • In general, snowfall is not dramatically high; however, frozen ground should not be proofrolled or compacted and fill should not be placed over frozen ground. 9.0 OBSERVATION OF CONSTRUCTION Recommendations provided in this report assume that GeoDesign will be retained to provide geotechnical consultation and observation services during construction. Satisfactory earthwork and foundation performance depends to a large degree on the quality of construction. Subsurface conditions observed during construction should be compared with those encountered during the subsurface explorations. Recognition of changed conditions often requires experience; therefore, GeoDesign personnel should visit the site with sufficient frequency to detect whether subsurface conditions change significantly from those anticipated and to verify that the work is completed in accordance with the construction drawings and specifications. Observation and laboratory testing of the proposed fill materials should be completed to verify that proposed fill materials are in conformance with our recommendations. Observation of the placement and compaction of the fill should be performed to verify it meets the required compaction and will be capable of providing the structural support for the proposed infrastructure and buildings. A sufficient number of in-place density tests should be performed as the fill is placed to verify the required relative compaction is being achieved. DDESIGN1' 29 KCHA-29-03:021814 DRAFT I 0.0 LIMITATIONS We have prepared this report for use by Vantage Point Apartments LLC, King County Housing Authority, and its consultants in design of this project. The data and report can be used for bidding or estimating purposes, but our report, conclusions, and interpretations should not be construed as warranty of the subsurface conditions and are not applicable to other nearby building sites. Exploration observations indicate soil conditions only at specific locations and only to the depths penetrated. They do not necessarily reflect soil strata or water level variations that may exist between exploration locations. If subsurface conditions differing from those described are noted during the course of excavation and construction, re-evaluation will be necessary. The site development plans and design details were preliminary at the time this report was prepared. If design changes are made, we request that we be retained to review our conclusions and recommendations and to provide a written modification or verification. The scope of our services does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor's methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No warranty, express or implied, should be understood . • • • We appreciate the opportunity to be of continued service to you. Please call if you have questions concerning this report or if we can provide additional services. Sincerely, GeoDesign, Inc. DRAFT DDESIGN, 30 KCHA-29·03:021814 DRAFT REFERENCES American Society for Testing and Materials, 2011. Annual Book of ASTM Standards, Vol. 4.08, Soil and Rock(l): D420-D4914, Philadelphia: ASTM. Booth, Derek B., Kathy A. Troost, and Aaron P. Wisher (2007), Geologic Map of King County, Compiled March 2007, GeoMapNW, scale 1:100,000. International Building Code, 2012. Johnson, S.Y., S.V. Dadisman,j.R. Childs, and W.D. Stanley, 1999, Active Tectonics of the Seattle Fault and Central Puget Sound, Washington: Implications for earthquake hazards,: GSA Bulletin, v. 111 , no. 7, p. 1042-1053. King County, 2009. Surface Water Design Manual, January 9, 2009. Nelson, A.R., S.Y. Johnson, S.K. Pezzopane, R.E. Wells, H.M. Kelsey, B.L. Sherrod, R.D. Koehler, R.C. Buckman, W.T. Laprade,J.W. Cox, and C.F. Narwolds, 2000. Postglacial and Late Holocene earthquakes on the Toe Jam Strand of the Seattle Fault, Bainbridge Island, Washington. Poster, GSA Cordilleran Seaion Meeting, Vancouver, Canada. Sherrod, B.L., T.M. Bracher, C.S. Weaver, R.C. Bucknam, RJ. Blakely, H.M. Kelsey, A.R. Nelson, and R. Haugerud, 2004, Holocene fault scarps near Tacoma, Washington, Geology, 32, p. 9-12. Washington State Department of Transportation, 2012. Standard Specifications for Road, Bridge and Municipal Construction. M 41-1 0. 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KCHA-29-03 EXISTING STEEP SLOPE AND EROSION HAZARD AREAS [llli0ES1GN~ 10700 Meridian "~nu, North· Suite 210 Suttl~WA98133 Off 206.838.9900 Fu 206.838.9901 FEBRUARY 2014 VANTAGE POINT APARTMENTS RENTON, WA FIGURE 5 Printed By: mmiller I Print Date: 2/17/2014 5:01 :14 PM FIie Name:J:\E-L\KCHA\KCHA-29\KCHA-29-03\Flgures\CAD\KCHA-29-03-SP02.dwg I Layout: FIGURE 6 >< V, ..,, =i ::1 m n..,, 0 !j; zz V, f= ~ :::lm z Cl C'1 0 ~z C'1 Cl z~ l:l :;; ;;o - V, z ~ C'1 >..,, z ;;o cO > :5 ;;o Cl -< m "' Cl ~~ 0 .. ~ vl Q r m z .,, m 3 0 . e· N 0 0 ----+- I II 'I I I •• ffl ,) 11, ~!j; /11''1 !I ' oml I, I I D So---.i ~ ~ENUESE -~ I: : ~:} -- ~_l Pl i!, ;,~ .. , i T I ~ ~ ~-1--'~~- z ~ ' I ... ~ I "' I I C'I !':' "' m I I z z I !=;I :::j ;;o m V, =i z d ---l m ~ 0 0 in ..,, .;, ..,, > V, 0 0 0 z --l .,, 0 .,, m V, --l V, m m --l "' --l ~ ..,, V, m C m m .,, "' V, r ..,, .,, ..,, 5 0 V, m V, ..,, ;;o z m 5 r 0 :c :c ..,, -., > > m m N N :c :c > > ~ > ;;o ;;o ~ Cl Cl > > ;;o ;;o ;;o ;;o Cl Cl ~ ~ > > ;;o ;;o .,, ~ ~ 0 r ~ ~ ~ z C'1 r r ;;o '1' z C'1 0 ~ "' C Cl .,, z .,, m C'1 ;;o ;;o m p C ;; m Cl t:, ~ .., .... •DESIGN~ KCHA-29-03 NEW STEEP SLOPE AND EROSION HAZARD AREAS 10700 Merid+.11'\ AVi!nue Nonh -Suite 210 Seattl~ WA 98133 Off 206.838.9900 fax 206,838.9901 FEBRUARY 2014 VANTAGE POINT APARTMENTS RENTON, WA FIGURE 6 APPENDIX A DRAFT APPENDIX A FIELD EXPLORATIONS GENERAL Subsurface conditions at the site were explored by completing five additional borings (B-5 through B-9) to depths ranging between 16.5 and 61.5 feet BGS. The borings were completed on December 19, 2013 by Geologic Drilling, Inc. of Spokane, Washington, using a trailer rig and hollow-stem auger drilling techniques. A well was installed to a depth of 60.0 feet BGS in boring B-6. The exploration logs from the recent explorations are included in this appendix. The locations of the explorations were determined in the field by using hand-held CPS equipment. This information should be considered accurate to the degree implied by the methods used. A member of our geotechnical staff observed the explorations. We obtained representative samples of the various soil encountered in the explorations for geotechnical laboratory testing. Samples were obtained using an SPT sampler at 2.5-and 5-foot intervals. SOIL CLASS/FICA T/ON The soil samples were classified in accordance with the "Exploration Key" (Table A-1) and "Soil Classification System" (Table A-2), which are included in this appendix. The exploration logs indicate the depths at which the soil or its characteristics change, although the change could be gradual. A horizontal line between soil types indicates an observed change. If the change was gradual the change is indicated using a dashed line. Classifications and sampling intervals are presented on the exploration logs included in this appendix. LABORATORY TESTING CLASS/FICA TION The soil samples were classified in the laboratory to confirm field classifications. The laboratory classifications are presented on the exploration logs if those classifications differed from the field classifications. CRAIN-SIZE ANALYSIS We completed grain-size testing in order to determine the distribution of soil particle sizes. The testing was completed in general accordance with ASTM D 422, ASTM C 136, ASTM C 11 7, and ASTM D 1140. The results of the testing are presented in this appendix. MOISTURE CONTENT We tested the moisture content in general accordance with ASTM D 2216. The moisture content is a ratio of the weight of the water to soil in a test sample and is expressed as a percentage. The overall moisture contents range from 20 to 24 percent. The results of the testing are presented in this appendix. A·l KCHA-29-03:021814 SYMBOL SAMPLING DESCRIPTION ~ Location of sample obtained in general accordance with ASTM D 1 586 Standard Penetration Test with recovery I Location of sample obtained using thin-wall Shelby tube or Geoprobe® sampler in general accordance with ASTM D 1587 with recovery I Location of sample obtained using Dames & Moore sampler and 300-pound hammer or pushed with recovery I Location of sample obtained using Dames & Moore and 140-pound hammer or pushed with recovery I Location of sample obtained using 3-inch-O.D. California split-spoon sampler and 140-pound hammer ~ Location of grab sample Graphic Log of Soil and Rock Types t 1··:·. .:~ •. -t ·~ / Observed contact between soil or I Rock coring interval ~,~; .. : rock units (at depth indicated) .~ .. ~ ... • I' 2 Water level during drilling / Inferred contact between soil or rock units (at approximate depths indicated) y Water level taken on date shown :-.--·. ' --- t.i::·.-· ~".: ,;-~ -· •., .... -t· ••• . . . GEOTECHNICAL TESTING EXPLANATIONS ATT Atterberg Limits pp Pocket Penetrometer CBR California Bearing Ratio P200 Percent Passing U.S. Standard No. 200 CON Consolidation Sieve DD Dry Density RES Resilient Modulus DS Direct Shear SIEV Sieve Gradation HYD Hydrometer Gradation TOR Torvane MC Moisture Content UC Unconfined Compressive Strength MD Moisture-Density Relationship vs Vane Shear oc Organic Content kPa Kilopascal p Pushed Sample ENVIRONMENTAL TESTING EXPLANATIONS CA Sample Submitted for Chemical Analysis ND Not Detected p Pushed Sample NS No Visible Sheen PID Photoionization Detector Headspace ss Slight Sheen Analysis MS Moderate Sheen ppm Parts per Million HS Heavy Sheen (i1D0ES1GN~ EXPLORATION KEY TABLE A-1 10100 MerldlanMnue North-suite 210 Semle WA 98133 Off 206.83&.9900 fax 206.838.990\ RELATIVE DENSITY -COARSE-GRAINED SOILS Relative Density Standard Penetration Dames & Moore Sampler Dames & Moore Sampler Resistance (140-pound hammer) (300-pound hammer) Very Loose 0-4 0 -11 0-4 Loose 4-10 11 -26 4 -10 Medium Dense 10 -30 26 -74 10-30 Dense 30 -50 74 -120 30 -47 Very Dense More than 50 More than l 20 More than 47 CONSISTENCY -FINE-GRAINED SOILS Consistency Standard Penetration Dames & Moore Sampler Dames & Moore Sampler Unconfined Compressive Resistance (l 4o-pound hammer) (300-pound hammer) Strength (tsf) Very Soft Less than 2 Less than 3 Less than 2 Less than 0.25 Soft 2-4 3-6 2-5 0.25 -0.50 Medium Stiff 4-8 6 -12 5-9 0.50 -1.0 Stiff 8 -15 12 -25 9 • 19 1.0 -2.0 Very Stiff 15 • 30 25 -65 19 -31 2.0 -4.0 Hard More than 30 More than 65 More than 31 More than 4.0 PRIMARY SOIL DIVISIONS GROUP SYMBOL GROUP NAME CLEAN GRAVELS ON or GP GRAVEL GRAVEL (< 5% fines) GRAVEL WITH FINES ON-GM or GP-GM GRAVEL with silt (more than 50% of (;,: 5% and s 12% fines) QN-GC or GP-GC GRAVEL with clay coarse fraaion COARSE-GRAINED retained on GM silty GRAVEL No. 4 sieve) GRAVELS WITH FINES GC clayey GRAVEL SOILS (> 12% fines) GC-GM silty' clayey GRAVEL (more than 50% CLEAN SANDS retained on SAND (<5% fines) SW or SP SAND No. 200 sieve) SW-SM or SP-SM SAND with silt SANDS WITT-I FINES (50% or more of (;e 5% and s l 2% fines) SW-SC or SP-SC SAND with clay coarse fraaion passing SM silty SAND No. 4 sieve) SANDS WITT-I FINES SC clayey SAND (> 12% fines) SC-SM silty, clayey SAND ML SILT FINE-GRAINED Liquid limit less than 50 CL CLAY SOILS CL-ML silty CLAY (50% or more SILT AND CLAY OL ORGANIC SILT or ORGANIC CLAY MH SILT passing Liquid limit 50 or No. 200 sieve) greater CH CLAY OH ORGANIC SILT or ORGANIC CLAY HIGHLY ORGANIC SOILS PT PEAT MOISTURE ADDITIONAL CONSTITUENTS CLASSIFICATION Secondary granular components or other materials Term Field Test such as oraanics, man-made debris, etc. Silt and Clay In: Sand and Gravel In: very low moisture, Percent Fine-Grained Coarse-Percent Fine-Grained Coarse- dry dry to touch Soils Grained Soils Solls Grained Soils moist damp, without <5 trace trace <5 trace trace visible moisture 5 -12 minor with 5 -15 minor minor visible free water, >12 some silty/clayey 15 -30 with with wet usually saturated > 30 sandy/gravelly Indicate% lw1111DESIGN~ SOIL CLASSIFICATION SYSTEM TABLE A-2 10700 t.terldlanAllentle North-Sult!! 210 Seimll! WA 98133 Off 206.838.9900 fax 206.836.9901 DRAFT· z Cl Q:,:: INSTALLATION AND 0 I.J w .& BLOW COUNT ~ !;;: Ii: z ...J COMMENTS DEPTH u MATERIAL DESCRIPTION f'C "-e MOISTURE CONTENT% FEET :i: >W ::; .. w Cl Vl ;,; llilJ RQO% c.7] CORE REC% :! ...J w w I- Cl 0 50 100 Medium dense, light brown SAND (SP), ' ' ' trace silt; dry to moist, fine. 5- ' ~ 26 Thin layer of gravel at top of •• sample. :.: ,,· .... · ' 10-dense; interbedded with dense light u • 30 '. brown with interbedded orange layered, • silty SAND (SM); moist, fine at 1 0.0 feet ' .... u 25 :A: . ' ' 15-., u : 2l -51EV ••• i ~-r---------------------: ·r ' Stiff, light brown with orange layered 17.0 -SILT with sand (ML); moist, sand is fine. u 15 .A: - ' ' 20-hard at 20.0 feet u ' :31 · sandy at 20.5 feet •• 25-' ' very stiff at 25.0 feet u 17 • gray at 25.5 feet : ..... . 30-' ' -u ·21 . •• Exploration completed at a depth of 31.5 Surface elevation was not measured at the time of 31.5 feet. exploration. 35- 40 ' 0 so 100 DRILLED BY: Geologic Drillng, Inc. LOGGED BY: TAP COMPLETED: 12f19113 80RINC METHOD: holloW-atem auger (see report text) BORING BIT OIAM£TER: 6-inch ttii•lDESI G N~ KCHA-29-03 BORING B-5 10700 Meridian Awnue North· Suite 210 VANTAGE POINT APARTMENTS I Seattle WA 98133 FEBRUARY 2014 FIGURE A·l Off 206,838.9900 Fax 206,838.9901 RENTON.WA DRAFT '-' It 0 Cl w .A. BLOW COUNT ~ z _J INSTALLATION AND DEPTH u f'= Cl. e MOISTURE CONTENT% 'i' MATERIAL DESCRIPTION w :; COMMENTS FEET ~ C V1 <( TIT] RQD% f77l CORE REC% ;:! _J w w I-V1 '-' 0 50 100 Dense, light brown SAND (SP), trace silt; . @ V l> Flush-mount dry to moist, fine, interbedded with monument with 2 dense light brown, silty SAND (SM); dry . '( feet of concrete to moist, fine. backfill Native backfill 5--· u 40 • • 2-lnch, Schedule 40 ... PVC well casing . . • • 10-u • 45 . :.1.: -Dense, light brown, silty SAND (SM); dry 12.5 u 28 to moist, fine. " 15-very dense; moist at 15.0 feet u • 114 SIEV -Ve_ry_stiff,Tight brown SILT with sand--17.0 (ML); moist, sand is fine. u 13 " Cuttings are wet at 18.0 feet . • . • 20-gray at 20.0 feet u 17 .... -Hard, gra,j; sandy SILT with gravel (ML); 23.0 moist to wet, sand is fine to medium, 25-gravel is fine to coarse. u • 31 " Cobble at 24.5 feet. Bentonite chips -Dense, gray, silty SAND (SM), minor 29.5 • • 30-u • gravel; wet, fine to medium, gravel is 38 Cuttings are very wet fine to coarse. ... at 30.0 feet. -Hard, gray SILT with sand (ML), minor 33.0 gravel; moist, sand is fine to medium, . gravel is fine. . ·.· 35-u . 54 interbed of hard CLAY (CH); dry at 35.5 .... feet ' " •, ii;.; : .) • :; 40 0 50 100 ' DRILLED BY: Geoio!Pc Drilling, Inc. LOGGED BY: TAP COMPLETED: 12/19113 BORING METHOD: holloW-Btem auger (see report text) BORING BIT DIAM£TER: 8-lnch tMi,jDESIG N:g KCHA-29-03 BORING B-6 10700 Meridian A~nue North· Suite 210 VANTAGE POINT APARTMElllTS SeattleWA.98133 FEBRUARY 2014 FIGURE A-2 Off 206.838.9900 Fax 206.838.9901 RENTON, WA DRAFT z (.J SE 9 .., UJ .& BLOW COUNT INSTALLATION AND DEPTH z ---' s! MATERIAL DESCRIPTION ~ UJ f'= "-e MOISTURE CONTENT% COMMENTS FEET a: UJCl V, ::; DIT RQD% 17'.7'.1 CORE REC% ;:; ---' UJ < UJ I-V, '--4 (.J 0 so 100 (continued from previous page) ~ : 42 ~ • ~ ;a ,;: '' ~ < C ~ ti ~ - ., j: Driller • ~ ., 45-~--' ,\':L ~~~;~~~:I from ~ 2 Dense, gray-brown SAND (SP), trace silt; 45.0 u :41 45.0 to 48.0 v wet, fine to medium. ... feet . .. · . 10 feet of water In ' hole at 45.0 feet. ~ ---------------------- Dense, gray SAND with silt (SP-SM), 4B.0 trace silt; moist to wet, fine to medium, I 0/20 flit er pack 50-gravel is fine. u ---'-----~ sand i.o . - -. = ' 2-lnch, slotted c-Schedule 40 PVC, ; = 0.01 0-lnch slot width -:·. ' -. . = ---. . 55-' - very dense at SS.O feet u 60 '. - -... E · .. • -.. ·· --. I ~ 60-~ rn 45 -:• ----- Exploration completed at a depth of 61.S Surface elevation was 61.5 feet. not measured at the time of exploration. 65- - • 70- • ' - ' 75--· -· - - - - 80 . 0 50 100 DRILLED BY: Geologic Drilling, Inc. LOGGED BY: TAP COMPLETED: 1211&'13 BORING METHOD: hollow-slam auger (see report text) BORING BIT DIAMETER: &h:h ttii110ES1GN\l1 BORING B-6 KCHA-29-03 (continued) 10700 Meridian Avenue North· Suite 210 VANTAGE POINT APARTMENTS Seattle WA 98133 FEBRUARY 2014 FIGURE A-2 Off 206.838.9900 Fax 206.838.9901 RENTON, WA b " z ~ 8 " ., " "' ' '-' DRAFT 0 ~ DEPTH u MATERIAL DESCRIPTION FEET ,: 0. ;;:; -'-' -Medium dense, brown SAND (SP), trace ' silt; dry to moist, fine. . s-' - -~ Very stiff, brown SILT with sand (ML); · - -moist, sand is fine. 10- dense; interbedded with dense, brown, silty SAND (SM); moist, fine at 12.S feet 15-~ Medium dense, gray SAND with silt (SP- SM); moist, fine. r------------------- Hard, gray, sandy SILT (ML); moist, sand Is fine. 20-very stiff at 20.0 feet I ' ' I 25- --... ----------------Very dense, gray, silty SAND with gravel 30-. (SM); moist, fine to medium, gravel is fine to coarse. - Exploration completed at a depth of 31.5 feet. - 35- 40 DRILLED BY: Geologic Drlllng, Inc. BORING METHOD: hollow-stem auger (see report text) [ij111iDESI G N:g KCHA-29-03 10700 Meridian Avenue North -Suite 210 Seattle WA 98133 Off 206.838.9900 Fax 206.838.9901 FEBRUARY 2014 I" INSTALLATION AND ,., UJ .. BLOW COUNT ~Ii: z ...J COMMENTS i= "-e MOISTURE CONTENT% >UJ ::; C V> [ill RQD% [7Z CORE REC% UJ <( ...J UJ t-V> 0 50 100 . . ~ · l-7 8.0 ~ -- 25 " ~ •• 40 SIEV " 14.S •• [ . 17 . " 17.0 ~ :31 . " ~ 28 " • • ~ 29 : " 29.0 Driller Comment: gravel at 29.0 feet. ~ 80 : " 31.S Surface elevatlon was not measured at the time of exploratlon. • . i i • I 0 50 100 LOGGED BY: TAP COMPLETED: 12/181'13 BORING BIT DIAMETER: 6-lnch BORING B-7 VANTAGE POINT APARTMENTS I FIGURE A-3 RENTON, WA DRAFT .., It <.:) .._ BLOW COUNT INSTALLATION AND 0 UJ ~ z ..J COMMENTS DEPTH u ~ ,,._ e MOISTURE CONTENT% FEET 'i' MATERIAL DESCRIPTION > UJ ::; TIIJ RQD% l2Z] CORE REC% ~ wCl w < ;:; ..J UJ f-V, ' .., 0 50 100 -Stiff, orange-brown, sandy SILT (ML), -trace gravel; moist, sand is fine to medium, gravel is fine. ~ 10: • s- :~--------------------- rn . 14 • 8.0 Dense, gray-brown SAND (SP), trace silt; Ori lier Comment: sand at dry to moist, fine to medium. B.o feet. . • 10-·_. ~ • 38 • . • ": .. · . .. . 15-very dense at 1 S.0 feet ~ Sl -·. Ji. • -Exploration completed at a depth of 16.S Surface elevation was not measured at the time of 16.5 feet. exploration. - • • • 20- • - 25- - - 30-~ - 35- 8 z ! . ~ • 40 ' 0 50 100 DRIU.ED BY: Geologic Driling, Inc. LOGGED BY: TAP COMPLETED: 12119/13 .., ~ BORING METHOD: holow-stemauger(see reportleJd) BORING BIT DIAMETER: 6-inch ~ iii•IDESIG N:g KCHA-29-03 BORING B-8 ~ z I ~ 10700 Meridian Avenue North · Suite 210 VANTAGE POINT APARTMENTS 0 Se.ittleWA98133 FEBRUARY 2014 FIGURE A-4 m Off 206.838.9900 Fax 206..838.9901 RENTON.WA DRAFT Cl 1~ INSTALLATION AND 0 l) "' .& BLOW COUNT ~ z _, COMMENTS DEPTH u ~ Q. e MOISTURE CONTENT% :i: MATERIAL DESCRIPTION "' ::. FEET ~ Cl "' ~ ]IT RQD% CZ] CORE REC% ~ _, "' t- -Cl 0 so 100 . Very dense, gray-brown SAND (SP), trace • - -silt; dry to moist, fine to medium. - - -• 5- • • • 10-~------~- interbedded with very dense, gray- -brown, silty SAND (SM); dry to moist, fine at 10.0 feet I 15-dense at 1 5.0 feet Exploration completed at a depth of 16.S Surface elevation was not measured at the time of 16.5 feet. exploration. - • • •• 20- - 25- • • 30--- 35-- 40 ' 0 50 100 DRILLED BY: Geologic Driling, Inc. LOGGED BY: TAP COMPLETED: 12/19/13 BORING METHOD: hollow-stem auger {see raport text) BORING BIT D1AM£TER: 6-incll ttiiejDESI G N~ KCHA-29-03 BORING B-9 10700 Meridian Avenue North· Suite 210 VANTAGE POINT APARTMENTS I Seattle WA 98133 FEBRUARY 2014 FIGURE A-5 Off 206.838.9900 Fax 206.83&.9901 RENTON, WA GRAIN SIZE NO P200 KCHA-29-03-85_9.GPJ GEODESIGN.GDT PRINT DATE: 2/12/14:KT U.S. STANDARD SIEVE NUMBERS DRAFT 3" l 1/2" 3/4" 3/8" 1 10 210 410 610 100 200 l_ -l J '1 ,, I I 100 -----r-~ ---~ ' I I ['»,, 90 . ' ' i ' 1 80 ----- !i: : '' !:J 70 ---- ! ·--·-· ~ ---· - I 3: ' : t 60 i "' .. - z 50 .: I-z 40 ---.. --u "' .. ... 30 ' - ' ' 20 L ____ - ' - 10 -~-. - 0 1,000 100 10 l 0.1 0,01 0.001 GRAIN SIZE IN MILLIMETERS I ;O~LDERS I ~ GRAVEL I COARSE]" SAND FINES CLAY I COBBLES : COARSE I FINE I I MEDIUM FINE SILT KEY EXPLORATION SAMPLE DEPTH MOISTURE CONTENT ---I GRAVEL SAND SILT , I CLAY : NUMBER (FEET) (PERCENn D60 D50 J D30 DlO D5 (PERCENn (PERCENn (PERCENn (PERCENn • --- :~ • B-5 15.0 24 0 17 IZI B-6 15.0 20 0 14 --- " B-7 12.5 24 ! 0 6 94 tMi•JDESIGN[g KCHA-29-03 GRAIN-SIZE TEST RESULTS 10700 Meridian Avenue North -SUlt<i 210 VANTAGE POINT APARTMENTS I FIGURE A-6 S..•t1ieW,_9&133 FEBRUARY 2014 Off 206.638.9900 filX 206,838.9901 RENTON,WA DRAFT SAMPLE INFORMATION SIEVE ATIERBERG LIMITS MOISTURE ORY EXPLORATION SAMPLE ELEVATION CONTENT DENSITY GRAVEL SANO P200 LIQUID PLASTIC PLASTICITY NUMBER DEPTH (FEEl) (PERCENT) (PCF) (PERCENT) (PERCENT) (PERCENT) LIMIT LIMIT INDEX (FEEl) (PERCENT) (PERCENT) (PERCENT) ' B-S 15.0 24 0 17 83 ---- B-6 15.0 20 0 14 86 B-7 12.5 24 0 6 94 --- ' LMi•iDESIGN~ KCHA-29-03 SUMMARY OF LABORATORY DATA 10700 Mi!rldl.an A11enufc North. Suitt 21 0 VANTAGE POINT APARTMENTS I SeanleWA98133 FEBRUARY 2014 FIGURE A-7 Off 206.838.9900 Fax 206.838.9901 RENTON, WA APPENDIX B § z 12 ~ '-' ' ' C> 0 ~ DEPTH u MATERIAL DESCRIPTION FEET :i: ~ :l . C> -. Soft, dark brown SILT with organics ~1 --\(roots); moist (topsoil). I I Stiff, brown SILT with concrete debris, cobbles, and boulders (ML), trace sand; moist, low plasticity, sand is fine -FILL. light brown, sandy at 3.75 feet 5- Dense, light brown with orange mottled SAND (SP); dry, fine. without mottles at 7.5 feet 10- . very dense at 10.0 feet I - 15-. trace silt at 16.0 feet - Very dense, light brown SAND with silt (SP-SM); dry, fine. 20-· with orange mottles at 20.5 feet . Very -,tiff, gray SILT (ML), trace sand; I dry, medium to high dry strength, low I plasticity, sand is fine. 25- I -i Very dense, gray, silty SAND (SM); dry, fine. 30- Hard, gray SILT (ML), trace sand; dry, medium to high dry strength, low 35-plasticity, sand is fine. 40 DRILLED BY: Holt s«vices, Inc. BORING METHOD: hollow-stem auger (see report text) tM1111DESIG N~ KCHA-29-01-02 10700 Meridian Avenue North· Sui~ 210 Seatt~ WA 98133 MARCH 2013 Off 206.838.9900 F.ax 206.838.9901 z QI INSTALLATION AND <., UJ _. BLOW COUNT ~t z .... COMMENTS f'C Q. e MOISTIJRE CONTENT% >"' ::;; u,Q if] <( o_I[ RQD% ;::=:] CORE REC% .... UJ f-V, 0 50 100 0.5 • • • u .11: " • Felt cobbles or rocks; hard I : 12· I drilling at 4.0 feet. • Debris encountered at 4.0 feet. Moving approximately 7.0 • 3 feet south. u '. 43 "' . --I 2~1'*5', • .--~ :61 " 18.0 [ ----· i.' • 22.5 u 2l .6.: - 28.0 -I lOBoutslde of sampler was wet at 30.0 feet. Perched water at approximately 30.0 feet. 33.0 ... --=---~------:--u 37 • " 0 50 100 LOGGED BY: TAP COMPLETED: 02/25113 BORING BIT DlAMITTR: 8-lnch . BORING B-1 VANTAGE GLEN -MULTI·FAMILY RENTAL PROJECT I FIGURE A-1 RENTON,WA ,., 0 ~ DEPTH u MATERIAL DESCRIPTION 'i' FEET ~ ;:; ,., -4 11 (continued from previous page) "' " ' ", ~ 0 ~ i ~ 9 " z "' al -Exploration completed at a depth of 41.5 feet. - 45- 50- 55- 60- - - 6S- 70- 75- . 80 DRIU.ED BY: Helt Services, Inc. BORING METHOD: 11o117.¥-stam sugar (see report text) twi1111DESIG N~ KCHA-29-01 ·02 10700 Meridian Avenue North -Suite 210 Seattle WA 98133 MARCH 2013 Off 206,838.9900 Fax 206.838.9901 z Q:c INSTALLATION AND I.J w .6. BLOW COUNT ~t z ..., COMMENTS i== C>. e MOISTURE CONTENT% >W :. wCl V1 LlilJ RQO% [2ZJ CORE REC% w <( ..., w f--V1 0 50 100 ~ • 37 •• 41.S Surface elevation was not measured at the time of exploration. • • • i -'- 0 50 100 LOGGED BY: TAP COMPLETED: 02/25113 BORING BIT DIAMITTR: 8-lnch BORING B·l (continued) I VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT FIGURE A-I RENTON,WA b " z " i:i Q s " " " ' ' C, g DEPTH u MATERIAL DESCRIPTION FEET :< ~ ~ C, Soft, brown SILT with sand (ML), trace gravel; moist, low dry strength, low plasticity, sand is fine, gravel is fine - FILL. . 5- Very stiff, light brown, sandy SILT (ML); dry, low dry strength, low plasticity, sand is fine -FILL. I 10-gray, with sand; medium dry strength at 10.0 feet Very stiff, gray, SILT (ML), trace sand; ' moist, sand is fine, medium dry 15-strength, low plasticity. I ' - 20-hard at 20.0 feet I I 25-becomes with sand, trace gravel; high dry strength, sand is fine to medium, gravel is fine at 25.0 feet Very dense, brown with orange mottled SAND with silt (SP-SM), minor gravel; 30-dry, fine to medium, gravel is fine. Very dense, brown SAND with gravel (SP); dry, fine to medium, gravel is fine. 35- 40 DRILLED BY: Holt Services, Inc. BORING METHOD: holl!Jw.stemaugar(saa report text) Mi110ES1G N~ KCHA-29-01-02 10700 Meridian A~nue North· Suite 210 Seanle WA 98133 MARCH 2013 Off 206.838.9900 Fax 206.838.9901 z QI INSTALLATION AND '-' w .& BLOW COUNT !.: I;:: z _, COMMENTS i= "-e MOISTURE CONTENT% >W ::. ~t' "' <( [CJ RQD% E::; CORE REC% w f-"' 0 50 100 ~ l • • I 7 ... 7.0 u 17 .... . I : 34 :.A_. 13.0 • [ • 27 • .... ~ : 32 . ... • u • - 60: .... 28.0 . I - ~91~1~··~ 33.0 . IJ ~8-5f.)/5• ! 0 50 100 LOGGED BY: TAP COMPLETED: 02/25/13 BORING BIT DIAMITTR: 8-lr,c:h BORING 8-2 VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-2 RENTON, WA " g DEPTH u MATERIAL DESCRIPTION FEET i :l -4: " interbeds of trace silt at 40.0 feet § z " ~ " ., " ' ' Exploration completed at a depth of . 41.25 feet. 45- - - so- 55- 60- 65- - - 70- - 7S- 80 DRILLED BY: Holt Servlcee, Inc. BORING METHOD: holow-st8m auger (see report text) lwl1111DES I G N:g KCHA-29-01-02 10700 Meridian Allf!nue North -Suite 210 Seattle WA 98133 MARCH 2013 Off 206.838.9900 Fax 206.838.9901 z Q :i: INSTALLATION AND '-' w .A. BLOW COUNT I;;: Ii: z ...J COMMENTS ~ "-e MOISTURE CONTENT% G'.i~ ::. ...J t:l < [ID RQD% z:J CORE REC% w f-V, 0 50 100 LI • I ·24-$9-5(),'J" .. 41.3 Surface elevatlon was not measured at the time of exploration. I i • . I • • - . • • -----~ • • 0 50 100 LOGGED BY: TAP COMPLITTD: 02/25/13 BORING BIT DIAMETER: 8-lnch BORING B-2 tcontlnuedl VANTAGE GLEN· MULTI-FAMILY RENTAL PROJECT I FIGURE A-2 RENTON,WA Zl '-' Oi:::r: <..:l .& BLOW COUNT INSTALLATION AND 0 f'.'.\: u.J ~ z ...J COMMENTS DEPTH ,, MATERIAL DESCRIPTION ~ru.J f'= "-e MOISTURE CONTENT% FEET I u.J (l "' ::;; [['.] RQD% E7'.J CORE REC% ~ ...J u.J <( ;;l u.J f-"' " '-' 0 50 100 Stiff, brown SILT (ML), trace sand; -moist, low dry strength, low plasticity, sand is fine -FILL. u 9 " ~Loos-e, light brown, silty SAND with 3.8 r Gray felt at approximately s-n\ gravel (SM); dry, fine to medium, gravel 4.5 4.0 feet. ' I - \is fine. / ia-78-100/5' Very dense,-brown with orange mottled SAND with gravel (SP), trace silt; dry, fine to medium, gravel is fine to coarse. u 76 •• - -10-- without mottles at 10.0 feet I i ia-1e-11XJ14• I • • 15-brown at 1 S.O feet I] --. -. .._ i Very dense, brown, silty SAND with 18.0 gravel (SM); dry, fine to medium, gravel 20--is fine to coarse. ---. - I I] i6--5ot5• SPT left in boring overnight. Large, smooth obstruction at approximately 21.0 feet. i Drilling refusal met at 21.0 feet; hole terminated. -Blew hydraulic hose at 21.0 Very dense, brown SAND with gravel 23.0 feet. (SW); dry, fine to coarse, gravel is fine •• Coarse gravel at approximately 22.0 feet 25-to coarse. -I] Moved boring approximately 42"'50/6" .. 1 O feet northwest of original ' boring down to 25.0 feet. - i 30-- ' I] ~7-50/5" 35-I i • 34-100/5" ' ' 40 0 50 100 DRILLED BY: Hott services, Inc. LOGGED BY: TAP COMPLETED: 02/26113 BORING METHOD: hobHtem auger (see raport taxi) BORING BIT DIAMETER: 8-lnch lMi•iDESIG N~ KCHA-29-01-02 BORING B-3 10700 Meridian Avenue North· Suite 210 VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I Seattle WA 98133 MARCH 2013 FIGURE A-3 Off 206.838.9900 Fax 206.838.!1901 RENTON, WA ., " ' ' <.) 0 ~ DEPTH u MATERIAL DESCRIPTION FEET r ~ ;:i <.) -·----Jcontinued from previous page) . Exploration completed at a depth of 40.5 feet. 45- - - - 50- ss- - 60- 65- - - 70- 75- - - 80 DRIUED BY: Holt Servita, Inc. BORING METHOD: hollow-stem auger (see report text) tfi11.1j0ESIGN~ KCHA-29-01-02 10700 Meridian Avenue North -Suite 210 Seattle WA 981 H MARCH 2013 Off 206,838.9900 Fax 206.838.9901 z Q:c <.:) ..t. BLOW COUNT INSTALLATION AND UJ ~t z .... COMMENTS ~ 0.. e MOISTURE CONTENT% > UJ ::. [III RQD% W CORE REC% UJCl UJ < .... UJ f-V, o so 100 II • : ':""'ii' 40.5 Surface elevation was not measured at the time of exploratlon. ' . • • • • --- • • o so 100 LOGGED BY: TAP COMPLETED: 02/26113 BORING BIT DIAMITTR: 8-lnch BORING B-3 (continued) VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-3 RENTON, WA § z ! " ., " ' ' " 0 ~ DEPTH u MATERIAL DESCRIPTION FEET 'i' .. :l -" . I Stiff, brown SILT with sand and gravel (ML); moist, low dry strength, low plasticity, sand is fine, gravel is fine - . FILL. I Very dense, light brown SAND (SP); dry, 5-fine to medium. ' - .. gray; moist, interbeds of very dense, gray, silty SAND (SM); moist, fine at 7.0 feet 10-. Hard, gray SILT with sand (ML); dry, high dry strength, low plasticity, sand is fine. Very dense, gray SAND (SP), minor 15- gravel, trace silt; dry, fine to medium, gravel is fine. ' ! Very dense, gray, silty SAND (SM); dry, ' fine, interbeds of very dense, gray 20-I SAND (SP); dry, fine. i - Hard, gray Sil T with sand (ML); dry, high dry strength, low plasticity, sand is fine. 25 - 30- - minor gravel at 31.0 feet . -I -I 35- ' interbeds of very dense, gray SAND (SP), -minor gravel; dry, fine to medium, · ' I gravel is fine at 35.0 feet Very dense, gray SAND (SP); dry, fine. 40 ·. DRILLED BY: Holt Services, Inc. BORING METHOD: hollcJW-6temauger(see report text) l•11i,1DEs1cN~ KCHA-29-01-02 10700 Meridian Aw,nue North· Suite 210 Seattle WA 98133 Off 206.838.9900 fax 206,838.9901 MARCH 2013 z QI INSTALLATION AND <..:J w .& BLOW COUNT !;;J: z _, COMMENTS i'C Q. e MOISTURE CONTENT% >w ::. w<:l :fl < ]IlJ RQD% D CORE REC% _, w f-V, a 50 100 . [ 9 " 4.0 Hard grinding at I ~ approximately 4.0 feet. 111 • u 57 " . I • 158 11.0 13.S [ · 84 :a.: 18.0 • •• . -~ u . 62: " . 23.0 u -· 58 : " --[ 66 " . • u • s2: " . I 38.0 Hard grinding at 38.0 feet. i • a 50 100 LOGGED BY: TAP COMPLETED: 02/28113 BORING BIT DIAM£TER: 8-lnch BORING B-4 VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-4 RENTON, WA z C, Q:,: L'l ... BLOW COUNT INSTALLATION AND 0 w ~ !;;:t z ...J COMMENTS DEPTH \,/ MATERIAL DESCRIPTION fC Q. e MOISTURE CONTENT% >"' ::;; FEET :,: wCl V\ OJI RQD% [ZJ CORE REC% ~ w <( ;:; ...J w ... V\ C, 0 50 100 ' 4v (continued from previous page) I 3~-1~· . . Exploration completed at a depth of 41.0 Surface elevation was not measured at the ti me of 41.0 feet. exploration. 45-_ _:_ ------.--:-----:-- - - 50 - 55-. . 60-. . 65- . 70 • • - - - 75 - - ;: ' - ' 80 0 50 100 DRILLED BY: Hott Se,vicas, Inc. LOGGED BY: TAP COMPlETED: 02/26113 BORING METHOD: hollow-stem auger (see report text) BORING BIT DIAMETER: 6-lnch tfi11110ES1 G N~ BORING B-4 KCHA-29-01-02 (continued) l 0700 Meridian Avenue North • Suite 210 VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I Seattle WA 98133 MARCH 2013 FIGURE A-4 Off 206.838.9900 Fax 206.838.9901 RENTON.WA 5 " z ~ " s " " " ' ' " 0 ~ DEPTH u 'i: MATERIAL DESCRIPTION FEET 0. ;;I " TP-1 0.0 ~ -_ TOPSOIL (6 inches). m / , Soft, brown SILT with sand (ML); moist, \ low dry strength, low plasticity, sand is : : : \fine -FILL. : : 2.5-Medium dense, light brown SAND (SP), - . trace gravel; moist, fine to medium, . gravel is fine . . dense at 3.5 feet 5.0- . . Very dense, light brown, silty SAND . (SM); dry, fine . 7.5- . . . . 10.0-· Exploration completed at a depth of 10.5 feet. . 12.5- TP-2 0.0 -Y-~ _TOPSOIL (6 inches). / I Soft, brown SILT with sand and gravel (ML); moist, low dry strength, low -I plasticity, sand is fine, gravel is fine to 2.5-i coarse -Fl LL. -J__ - Dense, light brown with orange mottled -SAND (SP), trace silt; dry, sand is fine. - 5.0- :, horizontal orange streaks at 5 .5 feet -very dense, without horizontal streaks -at 6.0 feet 7.5- - - - - 10.0- - - Exploration completed at a depth of -- 12.5- 12.0 feet. - - EXCAVATED BY: eor.ineotal Oirt Construction EXCAVATION METHOD: trackhoe {see report text) (ij1111DESIG N:g KCHA-29-01-02 10700 Meridian Avenue North -Suite 210 Seattle WA 98133 MARCH 2013 Off 206.838.9900 Fax 206.838.9901 ;~ " UJ z ...J eMOISTURE COMMENTS i= 0.. CONTENT >UJ :; UJ Cl "' UJ < (%) UJ f-"' 0 so 100 i • 0.5 '.;<] 1.0 '.;<] 6-inch orange streak at 2.0 feet. pp : PP= 2.35 tsf Nuclear density: 118.l pcf, moisture 1 8.6 percent at 4.0 feet. 6.0 ISl PP= >4.5 tsf 10.5 pp I><'. No groundwater seepage observed to the depth explored. No caving observed to the depth explored. Surface elevation was not measured at the time of • exploration . . 0 so 100 0 so 100 0.5 pp PP= l.O tsf ,., Nuclear density: 112.6 pcf, pp lz<I moiswre 13.5 percent at 3.5 feet. pp= 2.65 tsf ISl No groundwater seepage observed to the depth explored. No caving observed to the depth explored. 12.0 !ZJ Surface elevation was not measured at the ti me of exploration. ••• 0 50 100 LOGGED BY: TAP COMPLETED: 02/27/13 TEST PIT VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-5 RENTON, WA :: ' ~ ~ ' .; N 0 0 m N C, 0 ~ DEPTH u MATERIAL DESCRIPTION FEET 'i: ~ ~ C, TP-3 o.o """' TOPSOIL (6 inches). --~~ -Stiff, brown SILT with sand and -cobbles (ML), minor gravel; moist, low -dry strength, low plasticity, sand is 2.5-fine, gravel is fine to coarse -FILL. - - - - 5.0 Loose, gray, silty SAND wTth gravel and - • debris (SM); wet, fine to medium, .' gravel is fine to coarse, debris includes . . logs, copper pipe, and concrete brick - 7.5-FILL. . . i . . . . 10.0- Very dense, gray, silty SAND (SM); dry, \fine. I 12.S-Exploration completed at a depth of 11.5 feet. TP-4 0.0 TOPSOIL (6 inches). ' Soft to medium stiff, brown SILT (ML), -minor sand and gravel; moist, low dry -strength, low plasticity, sand is fine to 2.5-medium -FILL. 5.0- . Loose to medium dense, gray, silty . SAND to SAND with slit (SM/SP-SM), 7.5-minor gravel and debris (concrete, " wood, and pipe); wet -FILL. ' 10.0- Exploration completed at a depth of --- 12.5-11.5 feet. EXCAVATED BY: Continental Dirt.Construction EXCAVATION METHOD: trackhoe (seeraport lext) Lwii•IDESIGN~ KCHA-29·01-02 10700 Meridian Avenue North . Suite 21 O SeattleWA98133 MARCH 2013 Off 206.838.9900 Fax 206.838.9901 II c:, w f-1;: z ___, eMOISTURE ;;\ w f'= "-COMMENTS ::. CONTENT C VI w <( (%) f-VI 0 so 100 ' 0.5 pp ['xJ Nuclear density: 123.7 pcf, moisture 18.2 percent at 1.75 feet. pp= 2.5 tsf s.o ['xJ Moderate to severe caving observed at 6.0 feet. 11.0 PP ['xJ pp= >4.5 tsf 11.S No groundwater seepage observed to the depth explored. Surface elevation was not measured at the time of exploration . . ' 0 so 100 0 so 100 0.5 pp ['xJ Nuclear density: 123.2 pcf, moisture 16.5 percent at 2.0 feet. pp= 1.6 tsf Moderate caving observed at 5.0 feet. 6.0 [xJ No groundwater seepage observed ['xJ to the depth explored. 11.5 Surface elevation was not measured at the time of exploration. 0 so 100 LOGGED BY: TN> COMPLETED: 02127/13 TEST PIT VANTAGE GLEN. MULTI-FAMILY RENTAL PROJECT I RENTON. WA FIGUREA-6 " '-' ' ' Cl 0 ~ DEPTH u MATERIAL DESCRIPTION FEET 'i' .. ;;! Cl TP-5 0.0 .'¥ ... TOPSOIL (6 inches). - . ' Medium stiff, brown SILT with gravel . (ML), minor sand; moist, low dry 2.5- strength, low plasticity, sand is fine to medium -FILL. 5.0-Dense, light brown with orange mottled SAND with silt (SP-SM); moist, fine to medium. Very dense, brown SAND with gravel 7.5-(SW); moist, fine to coarse, . approximately 40% fine to coarse -,.9ravel. . I ' Exploration completed at a depth of 10.0-8.2 5 feet. 12.5- TP-6 0.0 '-''-'' • TOPSOIL (6 inches). Medium stiff, brown SILT with sand and cobbles (ML), minor gravel; moist, 2.5- low dry strength, low plasticity, sand is fine to medium, gravel is fine -FILL 5.0 Hard, gray, sandy SILT (ML); dry, high Ii dry strength, medium plasticity, sand is fine. j I 7.5 Exploration completed at a depth of 7 .5 feet. 10.0- 12.5- EXCAVATED BY: c.ontnental Dirt Construction EXCAVATION METHOD: trllC::khoa (see report text) ttii•lDESIGN~ KCHA-29-01-02 10700 Meridian Avenue North -Suite 210 Seattle WA 98133 MARCH 2013 Off 206.838.9900 Fax 206.838.9901 z J ' Q :i: '-' ~t z ---' eMOISTURE i:: 11 COMMENTS >"' CONTENT we V, (%) ---' UJ UJ f- 0 so 100 . 0.5 pp l2l PP=2.l tsf Nuclear density: 122.9 pd, 4.S pp I;?] moisture 20.7 percent at 4.5 feet. PP= 3.5 tsf 6.S No groundwater seepage observed l><I to the depth explored. No caving observed to the depth explored. 8.3 Surface elevation was not measured at the time of exploration. 0 so 100 0 so 100 o.s pp pp= 0.3 tsf pp l2l PP = 1.0 tsf Nuclear density: 118.5 pcf, moisture 1 9.8 percent at 4.0 feet. 5.0 pp l2l PP= >4.5 tsf Difficult to continue excavating. 7.5 No groundwater seepage observed to the depth explored. No caving observed to the depth explored. Surface elevation was not measured at the time of exploration. 0 so 100 LOGGED BY: TAP COMPLETED: 02/27/13 TEST PIT VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-7 RENTON, WA = ~ ~ ' ;;; N 0 0 m N g DEPTH u FEET :E ;;! Cl MATERIAL DESCRIPTION eMOJSTURE CONTENT (%) COMMENTS TP-7 0.0 ,'""'"r'rrCna"'"';c,.==:.-----------,----,-,--Or--:;50:.._. _ __.:;10;::0---------------J TOPSOIL (6 Inches). PP= 4.5 tsf 2.5- Stiff to very stiff, brown SILT with sand, gravel, and cobbles (ML), minor debris; moist, low dry strength, low plasticity, sand is fine to medium, gravel is fine to coarse -FILL. 0.5 5.0-l++++--------------,~=~=--l Very stiff to hard, gray, sandy SILT (ML); 5.0 dry, low dry strength, low plasticity, sand is fine. 7.5-I +'-+Yf--------- 10.0- 12.5- - - - . 1·., Very dense, light browri'SAND with silt, 8.o _:Jj gravel, and cobbles (SP-SM), moist, fine \ d / 90 1to me ium, gravel is fi_n_~ to coarse. 1 · Exploration completed at a depth of 9.0 feet. pp pp 181 pp 181 • I • Minor caving observed at 3.0 feet. PP= 2.0 tsf PP= >4.5 tsf Laminated pieces of light brown with orange streaked, fine, silty sand from 8.0 to 9.0 feet. No groundwater seepage observed to the depth explored. Surface elevation was not measured at the time of exploration. TP-8 o so 100 o.o,,-,,.'""f""T"O;,.;;;PS°'O""l"L'(;,6'1·n:cc::.h::e::s')---------,-.---r-r 0 ---' 5 ~ 0 --.'.':;: 00'.._-------------I -rn-i-t"''-'..::C...: • I 2.5- 5.0- Stiff, brown SILT with sand, gravel, and cobbles (ML); moist, low dry strength, low plasticity, sand is fine to medium, gravel is fine to coarse -FILL. 0.5 f-. ---- Very dense, gray, silty SAND (SM); dry, ,.o 7.5-~ fine. , I \orange layer at 8.0 feet ( 8 · 0 -I i Hard, light brown with orange mottled -SILT (MH), trace clay and sand; dry, 10·0 . I medium to high dry strength, medium r 10.0 . 12.S- '\to high plasticity, sand is fine, / laminated layers. I Exploration completed at a depth~ 10.0 feet. PP pp 181 pp pp= 2.2 tsf PP= 1.4 tsf PP• 3.5 tsf No groundwater seepage observed to the depth explored. No caving observed to the depth explored. Surface elevation was not measured at the time of exploration. ~,----'----'-------------......1.--'--'-+-'--'--'-k-'--'--'-',,l~---------< ~ O so 100 ~ f EXCAVATED BY: Cortlneotal Dirt Conatn.ictial LOGGED BY: TAP COMPLETED: 02/27/13 ~t-----------------------------___j ~ EXCAVATION METHOD: trackhoe (see 111portte:d) Nt------------,-----------,-----------------------------" ~ :.: tMi110ES1GN~ ~ 10700 Merldi;m Avenue North· Suite 210 .--Seattle WA 98133 Off 206.838.9900 Fax 206.838.~I KCHA-29-01-02 MARCH 2013 TEST PIT VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT I FIGURE A-8 RENTON, WA z " Q:,: 0 <.:J UJ ~ f-1;: z ...J eMOISTURE DEPTH ',! MATERIAL DESCRIPTION ~UJ f'= C. CONTENT COMMENTS FEET I ::. ~ UJC lfl ~1 (%) ::i ...J UJ f- Cl TP-9 0 50 100 0.0 'r'-"'• • TOPSOIL (6 inches). .-pp PP= 3.5 tsf ·stiff to very stiff, brown, gravelly SILT 0.5 with sand (ML); moist, low dry I strength, low plasticity, gravel is fine 2.5-to coarse, sand is fine to medium · FILL. pp k8l pp• 4.0 tsf -Nuclear density: 123.6 pcf, -Hard, dark brown, sandy SILT with ,.o moisture 18.5 percent at 3.5 feet. 5.0-! gravel (ML); dry, high dry strength, low -plasticity, sand is fine to medium, k8l I I gravel is fine to coarse, intermittent layers of clean gray fine to medium ! sand. 7.5- . : Hard, gray, sandy SILT with cobbles and 9.0 I No groundwater seepage observed . 10.0-boulders (ML), minor gravel; dry, high to the depth explored. dry strength, low plasticity, sand is fine, No caving observed to the depth -. gravel is fine. / explored. 11.0 Exploration completed at a depth of Surface elevation was not 12.S-11.0 feet. measured at the time of exploration . • TP-10 0 50 100 0 50 100 0.0 -. TOPSOIL (6 inches). Medium stiff, brown SILT with sand 0.5 and cobbles (ML), minor gravel; moist, 2.5- low dry strength, low plasticity, sand is fine to medium, gravel is fine to Moderate to severe caving coarse -FILL. observed from 3.0 to 7.0 feet. light gray layer at 4.0 feet 5.0-with large pieces of wood and debris at . 5.0 feet . . 7.5-boulder (3-foot diameter) at 7.0 feet . . . . 10.0-wood and concrete pieces at 10.0 feet [>". Slow groundwater seepage observed at l 0.0 feet. Surface elevation was not ' Exploration terminated due to severe 11.0 measured at the time of caving at a depth of 11 .0 feet. exploration. ' 12.S- : : . 0 50 100 EXCAVATED BY: Continental On Construction LOGGED BY; TAP COMPLETED: 02/27/13 EXCAVATION METHOD: trackhoe (SMI raport.lext) tfii1j0ESIGN~ KCHA-29-01-02 TEST PIT 10700 Meridian Avenue North· Suite 210 VANTAGE GLEN· MULTI-FAMILY RENTAL PROJECT Seattle WA 96133 MARCH 2013 FIGURE A-9 Off 206.838.9900 Fax 206.838.9901 RENTON, WA b " z I " ., " :: ' ' N " 0 ~ DEPTH ',! MATERIAL DESCRIPTION FEET :,: ~ ;:! " TP-11 0.0 ~TOPSOIL (6 inches). Medium dense, light brown, silty SAND (SM); moist, fine, laminated pieces. 2.5-dense to very dense; layers of orange at 2.5 feet 5.0---Exploration completed at a depth of 5.0 feet. 7.5- - - - - 10.0- 12.5- EXCAVATED BY: Continental Dirt.Construction EXCAVATION METHOD: trackhoe (see raportlext) r ... 1,iDEs1GN~ KCHA-29-01-02 10700 Meridian Avenue North -Suite 210 Seattle WA 98133 MARCH 2013 Off 206.838.9900 Fall 206..838.9901 1~ ._., UJ z _, eMOISTURE UJ j::: "-CONTENT COMMENTS ::; Q VI ~ (%) UJ UJ f- 0 so 100 ! : 0.5 l3l No groundwater seepage observed to the depth explored. No caving observed to the depth explored. 5.0 l3l Surface elevation was not measured at the time of exploration. • • 0 so 100 LOGGED BY; TAP COMPLITTD: 02/Z7/13 TEST PIT VANTAGE GLEN -MULTI-FAMILY RENTAL PROJECT 1 FIGUREA-10 RENTON,WA 9 Analytkal Re,oum,,, lnco,po,ated Analytical Chemists and Consultants 13 January 2014 Tyler Pierce GeoDesign, Inc. 10700 Meridian Avenue North, Suite 210 Seattle, WA98133 RE: Project: Samples Received 12130113 ARI Job No.: XS97 Dear Tyler: l<P&~lg,-D( kl-1+4 ·l.,Cf-0 l Please find enclosed the original Chain-of-Custody record (COC) and the final results for the samples from the project referenced above. Analytical Resources, Inc. (ARI) accepted four soil samples on December 30, 2013. The samples were analyzed for CEC and organic matter as requested. These analyses proceeded without incident of note. An electronic copy of this report and all supporting raw data will remain on file with ARI. Should you have any questions regarding these results, please feel free to contact me at your convenience. Respectfully, ANALYTICAL RESOURCES, INC. l no1.0'7a:i-. MarR D. Harris /".-- Project Manager 206/695-6210 markh@arilabs.com www.arilabs.com eFile: XS97 Enclosures MDH/mdh Page 1 of __ 1_ 1 _CfJ_ 4611 South 134th Place, Suite 100 • Tukwila WA 98168 • 206-695-6200 • 206-695-6201 fax J1:'lffllitel'~J<W"\C!'"o::T:!;'' •"·l'.':'."!i·>'L'.".·',.~,;;_q\•.:.9?'-;;_·-c.:~~:-, , .<1"\'<i'.:'.".7'',,0•,N'.'r>SCoi71fl.',c',XJ'. . ''•;•,>"'\";_/ ,,,, .. , ·,-::;:r, "C'.'i(/' ,-•• ,,~'1'fJ!';,;;-·:."h'WW'ft'Ff}.:,'.(::,x1-,w::.1:.-.'.<',f':'.!~!-:~;,-~1:t:: :-~>O"o"-·t :i:" 1:-·~ ~-·,7,ts'· .'~Y\t , .. ,, ;);,,-,_. ·1·::,,F'c"'/'.>. Chain of Custody Record & Laboratory Analysis Request ARI Assigned Number: A~ 1 I Turn-around Requested: Page: of • Analytical Resources, lncorporMed Analytical Chemists and Consultants ARl Client Company: G J. · I.,c Phone: (ZoG,) f 4 7--1 l/{h Date: Tice 4611 South 134th Place, Suite 100 "-c . e..S,71'\ Present? I\ \ Tukwila, WA 98168 . 206·695-6200 206-695-6201 (fax) Client Contact: T v1,,_( I:;\,,_, ce... No.of ([) Cooler '+ C www.arilabs.com Coolers: Temps: \ -6 Client Project Name: Analysis Requested Notes/Comments Client Project #: Samplers: J ;;i '-) Sample ID iJ \U Date Time Matrix No. Con1ainers t:"l '-.) () k.Pb l\5"·ll /3-l )-'-{ rz./ 3a lz<''' 3 ·. I\ sol I i X. ',( l(CH-4 2'f-c, s-, ,.3 --; 2 / ·~-v:,f ?..:a; 3 3, : { \ <;, '-\ l \ "><. X k.lHA 2'j-0-5 f3·z ~-:S ,2/3:,/z,..~ s 'I I s~.,1 I I-)<. JC-LHA Z'i-03 is-( S-~ 1i:/,c/,.,3 5·.11 s~J \ x' )l ~-. Comments/Special Instructions A~/inquished byu . .....j/' / p ___....-Received by:~ / Relinquished by: Received by: {Stgr1atun;-) ·.{,('G· I\ -J--_:,,. (Signature) / _.,.. ----__ . (Signature) (Signature) Printed Name: -,J Printed~m\ Printed Name: Printed Name: Ale,, L:ft•"-,u' /.:i. 1c.Ac,·1, rf,c-,r,n Company: . ., Gompafly: ' j Company: Company: G C.c, cl €..SL ,;YI.. .I r\.L ,· µ)(2_\ , Date & Time: -Date\;.:~r: "1 l Date & Time: Dale& Time: 12/~o-i&-,"', 3: r 2 I ,.._ ',( I -2, (SC' k....-:,,,4, ) \ ~[ Limits of Liability: ARI will perform afl requested services in accordance with appropriate methodology following ARI Standard Operating Procedures and the ARI Quality Assurance Program. This program ~ meets standards for the industry. The total liability of ARI, its officers, agents, employees, or successors, arising out of or in connection with the requested services, shall not exceed the Invoiced amount tor fi·\\li said services. The acceptance by the dient of a proposal tor services by ARI release ARI from any liability in excess thereof, not withstanding any provision to the contrary in any contract, purchase order or co- signed agreement between ARI and the Client. Sample Retention Policy: Atl samples submitted to ARI will be appropriately discarded no sooner than 90 days after receipt or 60 days after submission of hardcopy data, whichever is longer, unless alternate retention schedules have been established by work-order or contract. Anaitytk.Jl! Resrn...1rces, !nc:Jrporafred Anal-ytical Chemists and Consultants ARI Client _ _,(_,--1.] ,.,O;__(.cL"']"- 1 "'Y--''0..i.. ,cl(~; J"y_;lc_ __ COC No(s) -------------'Ci'JA Assigned ARI Job No· __ !\{_,,(~C...l~-)--'---- Project Name: ________ _,, ________ _ Delivered by: Fed-Ex UPS Courier ?a: De·l~·ered Other: __ _ ~---.......-/ Tracking No· _________________ _.(-NA, Preliminary Examination Phase: Were intact, properly signed and dated custody seals attached to the outside of to cooler? Were custody papers included with the cooler? . Were custody papers properly 1illed out (ink:, signed, etc) . Te. mperature qt_(;oo. ler(s) (°C) (recommended 2 0-6.0 °C for chemistry) YES ~) @ (§ NO NO Tome: J:2\? ill', __ If cooler temperature is out of compliance fill out form 00070F -T-e-mp G-u-n-lD-#:Cj(ff) :7·-2t)S;:.>. Cooler Accepted by: ____ ...,"c..~.cV.oc_ __________ Date· _rec.c:.>;,,k~ ... ·-)'J/.Lr _~.,· __ Time: i C:) te-;l Complete custody forms and attach all shipping documents log-In Phase: Was a temperature blank included in the cooler? ... YES {Ng / What kind of packing material was used? . Bubble Wrap Wei Ice Gel Packs 6$!~s Foam Block Paper Other:. _____ _ Was sufficient ice used (if appropriate)? . Were a!I bottles sealed in individual plastic bags? . Did all bottles arrive in good condition (unbroken)?. Were all bottle labels complete and legible? . Did the number of containers listed on COC match with the number of containers received?. Did all bottle labels and tags agree with custody papers? Were al! bottles used correct for the requested analyses? . Do any of the analyses (bottles} require preservation? (attach preservation sheet, excluding VOCs) .. Were all VOC vials free of air bubbles? Was sufficient amount of sample sent 1n each bottle?. Date voe Trip Blank was made at ARI ... NA f~) (0.~/ Was Sample Split by ARI : ~ YES Date/Time .. ·.------Equipment. _______ _ YES f? (('!: 'Nd f~. @ NO if~S' NO '!:is NO (@.s NO YES NO YES NO t©l NO Split by: 1 220-il; 1621 Samples Logged by. _____ _,[_;L. _____ _,.,ate; __ ., --=~-_aa,.,l-i.;;~-~.Jiwimnae:.,· =~~~~====--------- 'ti, Notify Project Manager of discrepancies or concerns ** Sample ID on Bottle Sample II?~~" CDC Sclrr\Oie ID on Bottle Additional Notes, Discrepancies, & Resolutions: B•: 1 $ma.II· Alr Bt:'1Jl;JleE1 • 0016F 312/10 -·?.mill 0 ' • Date: Peraoobbtei..' :2:1 -4 mm ®. ®• • -~~ .. I.Ar«o~ Mllub-Small -,, "sm" (<2mm) >4mm Peabubb)es ~ "pb,, ( 2 to< 4 mm) • • • Large, "lg" (4 to <6 mm) ·--·· ··-Headspac.e ~ "Its" ( >6 mm) ... Cooler Receipt Form Sample ID on COC . Revision 014 Sample ID l. KPG 18-01 B-2 S-4 2. KCHA 29-03 8-3 S-3 3. KCHA 29-03 B-2 S-3 4. KCHA 29-03 8-1 S-3 Sample ID Cross Reference Report ARI Job No: XS97 Client: GeoDesign Inc Project Event: N/A Project Name: N/A ARI ARI ANALYTICAL & AESOUACES9 INCORPORATED Lab ID LIM$ ID Matrix Sample Date/Time VTSR XS97A 13-28262 Soil 12/30/13 15: 11 12/30/13 XS97B 13-28263 Soil 12/30/13 15:11 12/30/13 XS97C 13-28/64 Soil 12/30/13 15: 11 12/30/13 XS97D 13-28265 Soil 12/30/13 15: 11 12/30/13 Printed 12/31/13 Page l of 1 15:12 15:12 15:12 15:12 · · 9 Analytkal Resoum,s, lnco,po,ated Analytical Chemists and Consultants I Client: GeoDesign, Inc. Case Narrative ARI Job No.: XS97 1. Four samples were submitted for analysis on December 31, 2013. 2. The samples were submitted for loss on ignition determination according to ASTM 02974, Method A and C. 3. The data is reported in percent, and is provided in summary tables. 4. There were no noted anomalies in the samples or methods on this project. Released by: §i~\,iQ.L- L Technician Reviewed by: ,Ja;(l.i +G {j;t.>z14c Geotechnical Laoratory Manager 4611 South 134th Place, Suite 100 • Tukwila WA 98168 • 206-695-620(1,•:'2Q.(r.;6'}5'~ft1,~..; ' •• ~ ••• ~,.. •• ·,;,c_ ·a,, •.• tl' -~-'--- • Analytical Resources, Incorporated Analytical Chemists and Consultants Data Reporting Qualifiers Effective 2/14/2011 Inorganic Data U Indicates that the target analyte was not detected at the reported concentration • B N NA H L Duplicate RPD is not within established control limits Reported value is less than the CRDL but ;;, the Reporting Limit Matrix Spike recovery not within established control limits Not Applicable, analyte not spiked The natural concentration of the spiked element is so much greater than the concentration spiked that an accurate determination of spike recovery is not possible Analyte concentration is S5 times the Reporting Limit and the replicate control limit defaults to ±1 RL instead of the normal 20% RPD Organic Data u • B J D E Q Indicates that the target analyte was not detected at the reported concentration Flagged value is not within established control limits Analyte detected in an associated Method Blank at a concentration greater than one-half of ARl's Reporting Limit or 5% of the regulatory limit or 5% of the analyte concentration in the sample. Estimated concentration when the value is less than ARl's established reporting limits The spiked compound was not detected due to sample extract dilution Estimated concentration calculated for an analyte response above the valid instrument calibration range. A dilution is required to obtain an accurate quantification of the analyte. Indicates a detected analyte with an initial or continuing calibration that does not meet established acceptance criteria ( <20%RSD, <20%Drift or minimum RRF). Page 1 of 3 9 s NA NR NS M M2 N y EMPC C p X Analytical Resources, Incorporated Analytical Chemists and Consultants Indicates an analyte response that has saturated the detector. The calculated concentration is not valid; a dilution is required to obtain valid quantification of the analyte The flagged analyte was not analyzed for Spiked compound recovery is not reported due to chromatographic interference The flagged analyte was not spiked into the sample Estimated value for an analyte detected and confirmed by an analyst but with low spectral match parameters. This flag is used only for GC-MS analyses The sample contains PCB congeners that do not match any standard Aroclor pattern. The PCBs are identified and quantified as the Aroclor whose pattern most closely matches that of the sample. The reported value is an estimate. The analysis indicates the presence of an analyte for which there is presumptive evidence to make a "tentative identification" The analyte is not detected at or above the reported concentration. The reporting limit is raised due to chromatographic interference. The Y flag is equivalent to the U flag with a raised reporting limit. Estimated Maximum Possible Concentration (EMPC) defined in EPA Statement of Work DLM02.2 as a value "calculated for 2,3,7,8-substituted isomers for which the quantitation and /or confirmation ion(s) has signal to noise in excess of 2.5, but does not meet identification criteria" (Dioxin/Furan analysis only) The analyte was positively identified on only one of two chromatographic columns. Chromatographic interference prevented a positive identification on the second column The analyte was detected on both chromatographic columns but the quantified values differ by 2'40% RPO with no obvious chromatographic interference Analyte signal includes interference from polychlorinated diphenyl ethers. (Dloxin/Furan analysis only) Z Analyte signal includes interference from the sample matrix or perfluorokerosene ions. (Dioxin/Furan analysis only} Page 2 of3 SAMPLE RESULTS-CONVENTIONALS XS97-GeoDesign Inc Matrix: Soil f Oata Release Authorized: Reported: 01/13/14 \, ' ' Project: Event: Date Sampled: Date Received: Analyta Total Solids Client ARI ID: KPG 18-01 B-2 S-4 ID: 13-28262 XS97A Data Method Units 01/03/14 SM2540G Percent 010314#1 Cation Exchange Capacity 01/08/14 9080 meq/100 g 010814#1 RL Analytical reporting limit D Dndetected at reported detection limit Soil Sample Report-XS97 NA NA 12/30/13 12/30/13 RL 0.01 0.01 ANALYTICAL IA RESOURCES\9' INCORPORATED Sampla 79. 97 0.88 SAMPLE RESULTS-CONVENTIONALS XS97-GeoDesign Inc Project: NA Event: NA Matrix: Soil ~ Data Release Authorized .) Reported: 01/13/14 \ J Date Sampled: 12/30/13 Date Received: 12/30/13 Client ID: KCHA 29-03 B-3 S-3 ARI ID: 13-28263 XS97B l\nalyte Date Method Units Total Solids 01/03/14 SM2540G Percent 010314#1 Cation Exchange Capacity 01/08/14 9080 meq/100 010814#1 RL Analytical reporting limit U Undetected at reported detection limit Soil Sample Report-XS97 RL 0.01 g 0.01 ANALYTICAL !ft\ RESOURCES'U' INCORPORATED Sample 79.96 8. 63 SAMPLE RESULTS-CONVENTIONAL$ XS97-GeoDesign Inc / Matrix: Soil I Data Release Authorized: Project: NA Event: NA Reported: 01/13/14 Date Sampled: 12/30/13 Date Received: 12/30/13 Analyta Total Solids Client ID: KCHA 29-03 B-2 S-3 ARI ID: 13-28264 XS97C Date Method Units 01/03/14 SM2540G Percent 010314#1 Cation Exchange Capacity 01/08/14 9080 meq/100 010814#1 RL Analytical reporting limit u Undetected at reported detection limit Soil Sample Report-XS97 RL 0.01 g 0.01 ANALYTICAL J& RESOURCES\9 INCORPORATED Salllpla 81. 41 7.35 Matrix: Soil Data Release Authorize Reported: 01/13/14 Analyte Total Solids \ Cation Exchange Capacity SAMPLE RESULTS-CONVENTIONALS XS97-GeoDesign Inc Project: Event: Date Sampled: Date Received: Client ID: KCIIA 29-03 B-1 S-3 ARI ID: 13-28265 XS97D Date Method Units 01/03/14 SM2540G Percent 010314#1 01/08/14 9080 meq/100 g 0108101 RL Analytical reporting limit U Undetected at reported detection limit Soil Sample Report-XS97 NA NA 12/30/13 12/30/13 ANALYTICAL. RESOURCES \9 INCORPORATED Sample 0.01 80.92 0.01 7.68 METHOD BLANK RESULTS-CONVENTIONALS XS97-GeoDesign Inc Matrix: Soil ~ Data Release Authorize: Reported: 01/13/14 · } Project: NA Event: NA Date Sampled: NA Date Received: NA Analyta Data Units Blank Total Solids 01/03/14 Percent < 0.01 Cation Exchange Capacity 01/08/14 meq/100 g 0.02 Soil Method Blank Report-XS97 u ANALYTICAL IA RESOURCES '9' INCORPORATED QC ID ICB PREP GEOTECHNICAL ANALYSIS DATA SHEET Organic Matter by Method ASTM D2974 Data Release Authorized:'Jl Reported: 01/08/14 f Date Received: 12/30/13 Page 1 of 1 QC Report No: XS97-GeoDesign Inc Project: Client/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 B-3 S-3 XS97B 13-28263 KCHA 29-03 B-2 S-3 XS97C 13-28264 KCHA 29-03 B-1 S-3 XS97D 13-28265 Date Sampled 12/30/13 12/30/13 12/30/13 12/30/13 Analysis Matrix Date Soil 01/06/14 10:45 Soil 01/06/14 10:45 Soil 01/06/14 10:45 Soil 01/06/14 10: 4 5 Organic/Ash Content Burn Temperature 440 C Fer ASTM D2974 Report for XS97 Result 45. 38 47.31 42.17 41. 87 ANALYTICAL/& RESOURCES\9 INCORPORATED GEOTECHNICAL ANALYSIS DATA SHEET Ash Content by Method ASTM D2974 Data Release Authorized:# Reported: 01/08/14 Date Received: 12/30/13 Page 1 of 1 Client/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 B-3 S-3 XS97B 13-28263 KCHA 29-03 B-2 S-3 XS97C 13-28264 KCHA 29-03 B-1 S-3 XS97D 13-28265 Date Sampled 12/30/13 12/30/13 12/30/13 12/30/13 QC Report No: XS97-GeoDesign Inc Project: Analysis Matrix Date Result Soil 01/06/14 10:45 54.62 Soil 01/06/14 10: 45 52.69 Soil 01/06/14 10:45 57.83 Soil 01/06/14 10: 45 58 .13 Organic/Ash Content Burn Temperature 440 C Per ASTM D2974 Report for XS97 ANALYTICAL & RESOURCES. INCORPORATED GEOTECHNICAL ANALYSIS DATA SHEET Total Solids by Method ASTM D2974 Data Release I\uthorized:'J'!,· Reported: 01/08/14 I Date Received: 12/30/13 Page 1 of 1 Client/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 B-3 S-3 XS97B 13-28263 KCHA 29-03 B-2 S-3 XS97C 13-28264 KCHA 29-03 B-1 S-3 XS97D 13-28265 Date Sampled 12/30/13 12/30/13 12/30/13 12/30/13 QC Report No: XS97-GeoDesign Inc Project: Analysis Matrix Date Result Soil 01/06/14 10:45 79.64 Soil 01/06/14 10: 45 79.42 Soil 01/06/14 10: 45 Bl. 30 Soil 01/06/14 10: 45 80.93 Report for XS97 ANALYTICAL a RESOURCES .. INCORPORATED 9 Analytkal Re,oum,s, lnco,po.ated Sa Analytical Chemists and Consu_ltants 17 January 2014 Tyler Pierce GeoDesign, Inc. 10700 Meridian Avenue North, Suite 21 O Seattle, WA 98133 RE: Project: Samples Received 12/30/13 ARI Job No.: XS97 Dear Tyler: Please find enclosed corrected reports for the samples from the project referenced above. As discussed, the original results for Organic Matter and Ash Content were incorrect due to an error in recording tare weights. The samples have been dried and re-weighed. An electronic copy of these reports will remain on file with ARI. Should you have any further questions, please feel free to contact me at your convenience. Respectfully, ANALYTICAL RESOURCES, INC. 71 o{ o(!Jaf!__ Ma'rk D. Harris Project Manager 206/695-6210 markh@arilabs.com www.arilabs.com eFile: XS97 Enclosures MDH/mdh Page 1 of r) ' 4611 South 134th Place, Suite 100 • Tukwila WA 98168 • 206-695-6200 • 206-695-6201 fax GEOTECHNICAL ANALYSIS DATA SHEET Organic Matter by Method ASTM D2974 Data Release Authorized:/l Reported: 01/17/14 . Date Received: 1,/30/13 Page 1 of 1 Client/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 8-3 S-3 XS97B 13-28263 KCHA 29-03 8-2 S-3 XS97C 13-28264 KCHA 29-03 8-1 S-3 XS97D 13-28265 Date Sampled 12/30/13 12/30/13 12/30/13 12/30/13 QC Report No: XS97-GeoDesign Inc Project: Analysis Matrix Date Result Soil 01/06/14 10:45 0.40 Soil 01/06/14 10:45 0.90 Soil 01/06/14 10:45 0.62 Soil 01/06/14 10:45 0.67 Reported in % Organic/Ash Content Burn Temperature 440 c Per ASTM D2974 Report for XS97 ANALYTICAL J& RESOURCES '9' INCORPORATED GEOTECHNICAL ANALYSIS DATA SHEET Ash Content by Method ASTM 02974 Data Release Authorized:CV,. Reported: 01/17/14 / Date Received: 12/30/13 Page 1 of 1 Cl.ient/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 8-3 S-3 XS978 13-28263 KCHA 29-03 B-2 S-3 XS97C 13-28264 KCHA 29-03 B-1 S-3 XS97D 13-28265 Date Sampled 12/30/13 12/30/13 12/30/13 12/30/13 QC Report No: XS97-GeoDesign Inc Project: Analysis Matrix Date Result Soil 01/06/14 10: 4 5 99.60 Soil 01/06/14 10:45 99.10 Soil 01/06/14 10: 45 99.38 Soil 01/06/14 10: 4 5 99.33 Reported in% Organic/Ash Content Burn Temperature 440 C Per ASTM D2974 Report for XS97 ANALYTICAL liill\ RESOURCES\9' INCORPORATED GEOTECHNICAL ANALYSIS DATA SHEET Total Solids by Method ASTM D2974 Dat._a Release Authorized:r Reported: 01/17/11 Date Received: 12/30/13' Page 1 of 1 Client/ ARI ID KPG 18-01 B-2 S-4 XS97A 13-28262 KCHA 29-03 B-3 S-3 XS97B 13-28263 KCHA 29-03 B-2 S-3 XS97C 13-28264 KCHA 29-03 8-1 S-3 XS97D 13-28265 QC Report No: XS97-GeoDesign Inc Project: Date Analysis Sampled Matrix Date Result 12/30/13 Soil 01/06/14 10: 45 79.64 12/30/13 Soil 01/06/14 10:45 79.42 12/30/ 13 Soil 01/06/14 10:45 81. 30 12/30/13 Soil 01/06/14 10:45 80.93 Reported in % Report for XS97 ANALYTICAL .a RESOURCES. INCORPORATED ACRONYMS ACRONYMS ADS ASTM ATB BGS CEC EPA g gpm GPS HMA H:V IBC KCHA kN/m' MCE MSE OSHA pcf pci psf PVC SPT SWDM wss advanced drainage system American Society for Testing and Materials asphalt-treated base below ground surface cation exchange capacity U.S. Environmental Protection Agency gravitational acceleration (32.2 feet/second') gallons per minute global positioning system hot mix asphalt horizontal to vertical International Building Code King County Housing Authority kilonewtons per square meter maximum considered earthquake mechanically stabilized earth Occupational Safety and Health Administration pounds per cubic foot pounds per cubic inch pounds per square foot polyvinyl chloride standard penetration test Surface Water Design Manual DRAFT Washington Standard Specifications for Road, Bridge, and Municipal Construction (201 2) KCHA-29-03:021814 AppendixD Construction Stormwater Polution Prevention Plan Vantage Point Apartments Technical Information Report Appendix D Stormwater Pollution Prevention Plan Owner King County Housing Authority For Vantage Point Apartments Prepared For Northwest Regional Office 3190 160th A venue Southeast Bellevue, WA 98008-5452 425-649-7000 Developer Project Site Location Operator/Contractor TBD 17901 105th Place Southeast, Renton WA, 98055 Certified Erosion and Sediment Control Lead TBD SWPPP Prepared By Christopher Borzio, PE KPFF Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle WA, 98101 SWPPP Preparation Date 12/09/2013 Approximate Project Construction Dates Start: TBD Finish: TBD n n Contents 1.0 Introduction ............................................................................................................................... ! 2.0 Site Description ....................................................................................................................... .3 2.1 Existing Conditions .......................................................................................................... .3 2.2 Proposed Construction Activities ..................................................................................... .3 3.0 Construction Stormwater BMPs ............................................................................................... 5 3.1 The 12 BMP Elements ....................................................................................................... 5 3.1.1 Element No. I -Mark Clearing Limits .............................................................. 5 3.1.2 Element No. 2 -Establish Construction Access ................................................ 5 3.1.3 Element No. 3 -Control Flow Rates .................................................................. 6 3.1.4 Element No. 4-Install Sediment Controls ........................................................ 6 3.1.5 Element No. 5 -Stabilize Soils .......................................................................... 7 3.1.6 Element No. 6 -Protect Slopes .......................................................................... 8 3.1.7 Element No. 7 -Protect Drain Inlets .................................................................. 8 3.1.8 Element No. 8 -Stabilize Channels and Outlets ................................................ 9 3.1.9 Element No. 9 -Control Pollutants .................................................................... 9 3.1.10 Element No. IO -Control Dewatering .............................................................. 9 3.1.11 Element No. 11 -Maintain BMPs .................................................................... 9 3.1.12 Element No. 12-Manage the Project ............................................................. 10 4.0 Construction Phasing and BMP Implementation ................................................................... 13 5.0 Pollution Prevention Team ...................................................................................................... 15 5.1 Roles and Responsibilities ............................................................................................... 15 5.2 Team Members ................................................................................................................ 15 6.0 Site Inspections and Monitoring ............................................................................................. 17 6.1 Site Inspection ................................................................................................................. 17 6.1.1 Site Inspection Frequency ................................................................................ 17 6.1.2 Site Inspection Documentation ......................................................................... 17 6.2 Stormwater Quality Monitoring ...................................................................................... 18 6.2.1 Turbidity ........................................................................................................... 18 6.2.2 pH ..................................................................................................................... 18 7.0 Reporting and Recordkeeping ................................................................................................ 21 7. I Recordkeeping ................................................................................................................. 21 7.1.1 Site Log Book ................................................................................................... 21 7.1.2 Records Retention ............................................................................................. 21 7 .1.3 Access to Plans and Records ............................................................................ 21 7.1.4 Updating the SWPPP ........................................................................................ 21 7 .2 Reporting ......................................................................................................................... 22 7 .2.1 Discharge Monitoring Reports ......................................................................... 22 7.2.2 Notification of Noncompliance ........................................................................ 22 ii n Appendix A -Site Plans ......................................................................................................... 22 Appendix B -Construction BMPs ......................................................................................... 23 Appendix C -Alternative BMPs ............................................................................................ 25 Appendix D -General Permit ................................................................................................ 27 Appendix E -Site Inspection Forms (and Site Log) .............................................................. 29 Appendix F -Engineering Calculations ................................................................................ .37 Appendix A Site plans • Vicinity map (with all discharge points) • Site plan with TESC measures Appendix B Construction BMPs • Possibly reference in BMPs, but likely it will be a consolidated list so that the applicant can photocopy from the list from the SWMM. Appendix C Alternative Construction BMP list • List of BMPs not selected, but can be referenced if needed in each of the 12 elements Appendix D General Permit Appendix E Site Log and Inspection Forms Appendix F Engineering Calculations (if necessary) • Flows, ponds, etc ... iii Stormwater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater pennit requirements for the Vantage Point Apartments construction project in Renton, Washington. The site is located at 17901 105th Place Southeast, Renton, Washington 98055 at the intersection of Southeast I 08th Street and 105th Place Southeast. The existing site is a 5.2-acre grassed lot with no surface improvements. The proposed development consists of two apartment buildings connected by a central common space, a rain garden, a detention pond, and landscaping. The north building is five levels and the south building is four levels, each including one level of underground parking. There are two surface parking lots, one associated with the north building and the other with the south. Construction activities will include excavation, grading, installation of on-site services/utilities, and construction of a four-and five-story apartment building. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: I. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate, or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts, including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Washington State Department of Ecology (Ecology) SWPPP Template downloaded from the Ecology website on December 9, 2013. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2005). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: • • Section I -INTRODUCTION. This section provides a summary description of the project and the organization of the SWPPP document. Section 2 -SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated storm water flow rates for existing conditions and post-construction conditions. • • • • • Stormwater Pollution Prevention Plan Section 3 -CONSTRUCTION BMPS. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP (SWMMWW 2005). Section 4-CONSTRUCTION PHASING AND BMP IMPIEMENTATION . This section provides a description of the timing of the BMP implementation in relation to the project schedule. Section 5 -POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the on-site temporary erosion and sedimentation control inspector Section 6-INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements, such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. Section 7 -RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A -Site plans Appendix B -Construction BMPs Appendix C -Alternative Construction BMP list Appendix D -General Permit Appendix E -Site Log and Inspection Forms 2 Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The project site is located at 17901 105th Place Southeast, Renton, Washington 98055. The existing site topography is the result of historical legal mining operations. The site is a relatively level grass covered bench projecting approximately 200 feet southward and westward from Southeast I 08th Street and I 05th Place Southeast. Grades on the bench vary from 5 percent to 25 percent sloping toward the roadway. Outward of the bench is a steep slope at upwards of 50 percent down to a neighboring community on Southeast 181 st Street. The project does not propose any clearing on the steep slope. Storm water sheets off of the existing site toward the City of Renton (City) owned collection system in Southeast 108th Street and 105th Place Southeast. Runoff generated from the steep slope flows to the collection system at the toe of slope. 2.2 Proposed Construction Activities The site area including the steep slope is 5.243 acres, and the limit of disturbance area for the project is 3.689 acres. The proposed development includes two apartment buildings connected by a central common space. The north building is five levels and the south building is four levels, each including one level of underground parking. There are two surface parking lots, one associated with the north building and the other with the south. Stormwater runoff from the proposed development will be collected in a series of catch basins and swales. Target pollution generating surfaces will be treated by an on-site rain garden to receive Enhanced Basic Water Quality Treatment. The treated runoff is then routed to a Level Two detention pond to protect downstream fish bearing streams. The detention pond outlets to the City owned storm drain in 105th Place Southeast. There is no change to the existing site discharge point. All runoff from property within city ROW that is within the limit of disturbance is considered bypass flow. The detention facility is designed with a downstream point of compliance that accounts for this bypass flow. The schedule and phasing of BMPs during construction is provided in Section 4.0. Stormwater runoff volumes were calculated using the King County Runoff Time Series (KCRTS). The temporary sedimentation pond that will be used during construction was designed using the 2-year storm event since construction will not occur over a long time-frame (approximately one year). The detention pond was designed using KCRTS. The live storage detention volume was designed by matching pre-and post-construction flows and durations for 50 percent of the 2-year flow and the SO-year flow. The pre construction flows are modeled as forested. The following summarizes details regarding site areas: • Total site area: 4.1 acres 3 Stormwater Pollution Prevention Plan • Percent impervious area before construction: 0 % • Percent impervious area after construction: 64 % • Disturbed area during construction: 4.0 I acres • Disturbed area that is characterized as impervious (i.e., access roads, staging, parking): 0 acres • 2-year stormwater runoff peak flow prior to construction (existing): 0.16 cfs • I 0-year stormwater runoff peak flow prior to construction (existing): 0.29 cfs • 2-year stormwater runoff peak flow during construction: 0.63 cfs • IO-year stormwater runoff peak flow during construction: 0.75 cfs • 2-year stormwater runoff peak flow after construction: 0.08 cfs • 10-year storm water runoff peak flow after construction: 0.15 cfs All stormwater flow calculations are provided in TIR. 4 Stormwater Pollution Prevention Plan 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element No. 1 -Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: BMP Cl O l: Preserving Natural Vegetation BMP Cl03: High Visibility Plastic or Metal Fence Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Storm water permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element No. 2 -Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized; yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: BMP C 105: Stabilized Construction Entrance Alternate construction access BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 5 Stormwater Pollution Prevention Plan 3.1.3 Element No. 3-Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: BMP C241: Temporary Sediment Pond Alternate flow control BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element No. 4 -Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: BMP C233: Silt Fence BMP C24 l: Temporary Sediment Pond Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirement5 set forth in the General NPDES Penni! (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater pennit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into on-site, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). 6 Stormwater Pollution Prevention Plan In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent storm water BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. The following BMPs will be implemented as end-of-pipe sediment controls as required to meet pennitted turbidity limits in the site discharge(s). Prior to the implementation of these technologies, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sedimentation controls. BMP C250: Construction Stormwater Chemical Treatment (implemented only with prior written approval from Ecology). BMP C25 l: Construction Stormwater Filtration 3.1.5 Element No. 5 -Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: BMP Cl 20: Temporary and Permanent Seeding BMP C 122: Nets and Blankets BMP C123: Plastic Covering BMP Cl 25: Topsoiling BMP C140: Dust Control Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater pennit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 7 Stormwater Pollution Prevention Plan 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shallbe stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and, where possible, be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element No. 6 -Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner that minimizes erosion. The following specific BMPs will be used to protect slopes for this project: BMP C200: Interceptor Dike and Swale BMP C201: Grass-Lined Channels BMP C204: Pipe Slope Drains BMP C208: Triangular Silt Dike (Geotextile-Encased Check Dam) Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the on- site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element No. 7 -Protect Drain Inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: BMP C220: Storm Drain Inlet Protection If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment 8 Stormwater Pollution Prevention Plan Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element No. 8 -Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: BMP C202: Channel Lining BMP C209: Outlet Protection Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the on-site inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.9 Element No. 9 -Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. BMP Cl51: Concrete Handling BMP C 152: Sawcutting and Surfacing Pollution Prevention This section of the report shall be expanded by the contractor after workplan and construction methods are established. 3.1.10 Element No. 10-Control Dewatering Foundation, vault, and trench de-watering water, which have similar characteristics to stormwater runoff at the site, shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Channels must be stabilized, as specified in Element No. 8. 3.1.11 Element No. 11 -Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair 9 Stormwater Pollution Prevention Plan shall be conducted in accordance with each particular BMP specification (attached). Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-storm water discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMP are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element No. 12 -Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: • • • • • • • Design the project to fit the existing topography, soils, and drainage patterns . Emphasize erosion control rather than sediment control. Minimize the extent and duration of the area exposed . Keep runoff velocities low . Retain sediment on site . Thoroughly monitor site and maintain all ESC measures . Schedule major earthwork during the dry season . In addition, project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction • • The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). 10 Stormwater Pollution Prevention Plan Seasonal Work Limitations • From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: • • o Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; D Limitations on activities and the extent of disturbed areas; and D Proposed erosion and sediment control measures. Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations: D Routine maintenance and necessary repair of erosion and sediment control BMPs; o Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and D Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions • Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. Inspection and Monitoring • All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: 11 Stormwater Pollution Prevention Plan o Assess the site conditions and construction activities that could impact the quality of stormwater, and D Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. • A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. • Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP • • • This SWPPP shall be retained on-site or within reasonable access to the site . The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. 12 • stabilization products: • Install ESC measures: • Install stabilized construction entrance: • Begin clearing and grubbing: 13 Stormwater Pollution Prevention Plan TBD TBD TBD TBD Stormwater Pollution Prevention Plan 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: • • • • • • Certified Erosion and Sediment Control Lead (CESCL) -primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. Resident Engineer -For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative. Emergency Ecology Contact -individual to be contacted at Ecology in case of emergency. Emergency Owner Contact -individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. Non-Emergency Ecology Contact -individual that is the site owner or representative of the site owner than can be contacted if required. Monitoring Personnel -personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD - Resident Engineer -- Emergency Ecology Contact -- Emergency Owner Contact -- Non-Emergency Ecology Contact -- Monitoring Personnel -TBD 15 Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: • • A record of the implementation of the SWPPP and other permit requirements; Site inspections; and • Stormwater quality monitoring . For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL) per BMP C 160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month. 6.1.2 Site Inspection Documentation The site inspector will record each site in_spection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but 17 Stormwater Pollution Prevention Plan will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.2 Stormwater Quality Monitoring 6.2.1 Turbidity Turbidity sampling and monitoring will be conducted during the entire construction phase of the project. Samples will be collected daily at Catch Basin (CB) No. 8056 (as shown on site survey) at the sediment pond point of connection to 105th Place Southeast. If there is no flow in this catch basin, the attempt to sample will be recorded in the site log book and reported to Ecology in the monthly Discharge Monitoring Report (DMR) as "No Discharge". Samples will be analyzed for turbidity using the EPA 180.1 analytical method. The key benchmark turbidity value is 25 nephelometric turbidity units (NTU) for the downstream receiving water body. If the 25 NTU benchmark is exceeded in any sample collected from CB No. 8056, the following steps will be conducted: 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document modified BMPs in the SWPPP as necessary. 3. Sample discharge daily until the discharge is 25 NTU or lower. If the turbidity exceeds 250 NTU at any time, the following steps will be conducted: I. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue sampling daily until the discharge is 25 NTU or lower Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours, and implement those additional treatment BMPs as soon as possible, but within a minimum of 7 days. 3. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling and monitoring for pH will occur during the phase of construction when concrete pouring will be conducted until fully cured (3 weeks from last pour) and discharges are documented to be below pH 8.5. Samples will be collected weekly at the sedimentation pond prior to 18 Stormwater Pollution Prevention Plan discharge to surface water. Samples will be analyzed for pH using a calibrated pH meter and recorded in the site log book. The key benchmark pH value for stormwater is a maximum of 8.5. If a pH greater than 8.5 is measured in the sedimentation trap/pond(s) that has the potential to discharge to surface water, the following steps will be conducted: I. Prevent (detain) all discharges from leaving the site and entering surface waters or storm drains if the pH is greater than 8.5 2. Implement CO2 sparging or dry ice treatment in accordance with Ecology BMPC252. 3. Describe inspection results and remedial actions that are taken in the site log book and in monthly discharge monitoring reports as described in Section 7 .0 of this SWPPP. 19 Stormwater Pollution Prevention Plan 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements; • • Site inspections; and Stormwater quality monitoring . For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. 7 .1.2 Records Retention Records of all monitoring information (site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimwn of 3 years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s) that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. 21 Stormwater Pollution Prevention Plan 7 .2 Reporting 7.2.1 Discharge Monitoring Reports If cumulative soil disturbance is smaller than 5 acres: Discharge Monitoring Report (DMR) forms will not be submitted to Ecology because water quality sampling is not being conducted at the site. If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period, the Permittee shall submit the form as required, with the words "No discharge" entered in the place of monitoring results. The DMR due date is 15 days following the end of each month. 7 .2.2 Notification of Noncompliance If any of the terms and conditions of the permit is not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: 1. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within 5 days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within 5 days, unless requested earlier by Ecology. In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit. 22 Stormwater Pollution Prevention Plan Appendix B -Construction BMPs The following includes a list of the BMPs to be implemented on the site. BMP CIOI: Preserving Natural Vegetation BMP Cl 03: High Visibility Plastic or Metal Fence BMP CI 05: Stabilized Construction Entrance BMP C24 l: Temporary Sediment Pond BMP C233: Silt Fence BMP C24 l: Temporary Sediment Pond BMP CJ20: Temporary and Permanent Seeding BMP C 122: Nets and Blankets BMP CJ23: Plastic Covering BMP CJ25: Topsoiling BMP Cl 40: Dust Control BMP C200: Interceptor Dike and Swale BMP C201: Grass-Lined Channels BMP C204: Pipe Slope Drains BMP C208: Triangular Silt Dike (Geotextile-Encased Check Dam) BMP C220: Storm Drain fulet Protection BMP C202: Channel Lining BMP C209: Outlet Protection BMP Cl 5 l: Concrete Handling BMP C152: Sawcutting and Surfacing Pollution Prevention 23 4.1 Source Control BMPs BMP C101: Preserving Natural Vegetation Pu,pose C 011ditio11s of Use Design a11d Instalfation Specijicatio11s 4-2 The purpose of preserving natural vegetation is to reduce erosion wherever practicable Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the stonn. • Natural vegetation should be preserved on steep slopes, near perennial and intermittent watercourses or swales, and on building sites in wooded areas. • As required by local governments. Natural vegetation can be preserved in natural clumps or as individual trees. shrubs and vines. The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The po111ts to remember when attempting to save individual plants are: • ls the plant worth saving'/ Consider the location. species, size, age. vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. • Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: • Construction Equipment -This injury can be above or below the ground level. Damage results from scarring. cutting of roots, and compacl1011 of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction eqmpment 1111unes • Grade Changes -Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause problems although sensitivity between species does vary and should be checked. Trees can tolerate fill of 6 inches or Jess. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. A tile Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 system protects a tree from a raised grade. The tile system should be laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots arc exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by lea,ing them on an undisturbed, gently sloping mound. To increase the chances for smvival, it is best to limit grade changes and other soil disturbances to areas outside the driphne of the plant. • Excavations -Protect trees and other plants when excavating for drninfields. power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed, Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint. Backfill the trench as soon as possible. Tunnel beneath root systems as close to the center of the main tnmk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are, • Maple, Dogwood. Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. • The windthrow hazard of Pacific silver fir and madronna is high, while that of Western hemlock is moderate. The danger ofwindthrow mcreases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, Volume II -Construction Stormwater Pollution Prevention 4-3 Maintenance Standards 4-4 Pacific dogwood, and Red alder can cause serious disease problems. Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. • Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. • If tree roots have been exposed or injured, "prune" cleanly with an appropriate pruning saw or lopers directly above the damaged roots and recover with native soils. Treatment of sap nowing trees (fir, hemlock, pine, soft maples) is not advised as sap fonns a natural healing barrier. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C103: High Visibility Plastic or Metal Fence Pwpose Conditions of Use Design and /11sta{/ation Specifications Mai11te11a11ce Standards 4-6 Fencing is intended to: (1) restrict clearing to approved limits: (2) prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed: (3) limit construction traffic to designated construction entrances or roads: and, ( 4) protect areas where marking with survey tape may not provide adequate protection. To establish clearing limits, plastic or metal fence may be used: • At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. • As necessary to control vehicle access to and on the site. • High visibility plastic fence shall be composed of a high-density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM 04595 testing method. • Metal fences shall be designed and installed according to the manufacturer's specifications. • Metal fences shall be at least 3 feet high and must be highly visible. • Fences shall not be wired or stapled to trees. , If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C105: Stabilized Construction Entrance Purpose Cm,ditim,s of Use De.rign and Installation Specifications 4-8 Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by vehicles or equipment by constructing a stabilized pad of quarry spalls at entrances to construction sites. Construction entrances shall be stabilized wherever traffic will be leaving a constrnction site and traveling on paved roads or other paved areas within 1,000 feet of the site. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Constrnction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. • See Figure 4.2 for details. Note: the 100' minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100'). • A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The gcotcxtile shall meet the following standards: Grab Tensile Strength (ASTM 04751) 200 psi min Grab Tensile Elongation (ASTM 04632) 30% max. Mullen Burst Strength (ASTM 03786-80a) 400 psi min. AOS (ASTM 04751) 20-45 (U.S. standard sieve size) • Consrder early installation of the first lift of asphalt in areas that will paved: this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for thrs purpose. • Hog fuel (wood-based mulch) may be substituted for or combined with quarry spalls in areas that will not be used for permanent roads. Hog fuel is generally less effective at stabilizing construction entrances and should be used only at sites where the amount of traffic is very limited. Hog fuel is not recommended for entrance stabilization in urban areas. The effectiveness of hog fuel is highly variable and it generally requires more maintenance than quarry spalls. The inspector may at any time require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto pavement or if the hog fuel is being can-ied onto pavement. Hog fuel is prohibited in permanent roadbeds because organics in the subgrade soils cause degradation of the subgrade support over time. • Fencing (see BMPs Cl03 and Cl04) shall be installed as necessa1y to restrict traffic to the constrnction entrance. Volume II -Construction Stormwater Pollution Prevention February 2005 Maintenance Standards February 2005 • Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. • Quany spalls (or hog fuel) shall be added if the pad is no longer in accordance with the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump shall be considered. The sediment would then be washed into the sump where it can be controlled. • Any quany spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMPs CI03 and Cl04) shall be installed to control traffic. • Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be ermanentl stabilized. Driveway shaR mee-1 lhe reQuirements of the permi1ting agency 11 ls recommended that tile entrance be c1own&d so 1hat runo11 drains off \he pad ) Figure 4.2 -Stabilized Construction Entrance Volume II -Construction Stormwater Pollution Prevention 4-9 BMP C241: Temporary Sediment Pond Pwpose Conditions of Use Design and lnstalfation Specijications February 2005 Sediment ponds remove sediment from runoff originatmg from disturbed areas of the site. Sediment ponds are typically designed to remove sediment no smaller than medium silt (0.02 mm). Consequently, they usually reduce turbidity only slightly. Prior to leaving a construction site, storm water runoff must pass through a sediment pond or other appropriate sediment removal best management practice. A sediment pond shall be used where the contributing drainage area is 3 acres or more. Ponds must be used in conjunction with erosion control practices to reduce the amount of sediment flowing into the basin. • Sediment basins must be installed only on sites where failure of the structure would not result in loss of life, damage to homes or buildings, or interruption of use or service of public roads or utilities. Also. sediment traps and ponds are attractive to children and can be very dangerous. Compliance with local ordinances regarding health and safety must be addressed. If fencing of the pond is required, the type of fence and its location shall be shown on the ESC plan. • Structures having a maximum storage capacity at the top of the dam of IO acre-ft (435,600 ft 3) or more are subject to the Washington Dam Safety Regulations (Chapter 173-175 WAC). • See Figure 4.24, Figure 4.25, and Figure 4.26 for details. • lfpennanent runoff control facilities are part of the project, they should be used for sediment retention. The surface area requirements of the sediment basin must be met. This may require enlarging the permanent basin to comply with the surface area requirements. J fa pem1anent control structure is used, it may be advisable to partially restrict the lower orifice with gravel to increase residence time while still allowing dewatering of the basin. • Use of infiltration facilities for sedimentation basins during construction tends to clog the soils and reduce their capacity to infiltrate. If infiltration facilities are to be used, the sides and bottom of the facility must only be rough excavated to a minimum of 2 feet above final grade. Final grading of the infiltration facility shall occur only when all contributing drainage areas are fully stabilized. The infiltration pretreatment facility should be fully constructed and used with the sedimentation basin to help prevent clogging. • Detem1ining Pond Geometry Obtain the discharge from the hydro logic calculations of the peak flow for the 2-year runoff event (Q2). The I 0-year peak flow shall be used if the project size, expected timing and duration of construction, or downstream conditions warrant a higher level of protection. Ifno hydrologic analysis is required, the Rational Method may be used. Volume II -Construction Stormwater Pollution Prevention 4-105 4-106 Detem1ine the required surface area al the top of the riser pipe with the equation: SA ~ l x Qi0.00096 or 2080 square feet per cfs of inflow See BMP C240 for more infom1ation on the derivation of the surface area calculation. The basic geometry of the pond can now be determined using the following design criteria: • Required surface area SA (from Step 2 above) at top ofriser. • Ylinimum 3.5-foot depth from top of riser to bottom of pond. • Maximum 3:J interior side slopes and maximum 2:1 exterior slopes. The interior slopes can be increased to a maximum of2:l if fencing is provided at or above the maximum water surface. • One foot offreeboard between the top of the riser and the crest of the emergency spillway. • Flat bottom. • 'vlmimum !-foot deep spillway. • Length-to-width ratio between 3: 1 and 6: 1. • Sizing of Discharge Mechanisms. The outlet for the basin consists of a combination of principal and emergency spillways. These outlets must pass the peak runoff expected from the contributing drainage area for a l 00-year stonn. If, due to site conditions and basin geometry, a separate emergency spill-way is not feasible, the principal spillway must pass the entire peak runoff expected from the 100-year sto1111. However, an attempt to provide a separate emergency spillway should always be made. The runoff calculations should be based on the site conditions during construction. The !low through the dewatering orifice cannot be utilized when calculating the 100-year storm elevation because of its potential to become clogged; therefore, available spillway storage must begin at the principal spillway riser crest. The principal spillway designed by the procedures contamed in this standard will result m some reduction in the peak rate of runoff However. the riser outlet design will not adequately conn·ol the basin discharge to the predevelopmcnt discharge limitations as stated in Minimum Reqmrement #7 Flow Control. However. if the basin for a pernianent stonmvater detention pond is used for a temporary sedimentation basin, the control structure for the permanent pond can be used to maintain predevelopment discharge limitations, The size of the basin, tbe expected life of the construction project, the anticipated downstream effects and the anticipated weather conditions during construction, should be considered to dete1mine the need of additional discharge coutroL See Figure 4.28 for riser inflow curves. Volume II -Construction Stormwater Pollution Prevention February 2005 The pond length shall be 3 to 6 times the maximum pond width Inflow " Note: Pond may l>e formed by berm or ~-=--~---? by partial Of complete excavation ii Figure 4.24 -Sediment Pond Plan View Riser pipe (principal spillway) Crest of open at top with trash rack emergeni 6' min. Width Dewatering device Dewatenng Concrete base 1--l=ilsm Discharge to stabilized -·_!=!I= Wire·backed silt fence staked haybaJes wrapped wifh ffl:er fabric, or equivalent divider orifice (see riser detail) conveyance outlet or level spreader Figure 4.25 -Sediment Pond Cross Section Polyethylene cap Provide adequate ... /app,ng I Perforated polyethylene - drainage tubing, diame~ -Corrugated min. 2" larger than metal nser dewatering orifice. 3.s· min. Tubing shall comply -Watertight Oewatertng orifice, schedule. with ASTM F667 and - AASHTOM294 = coupl\" i/ckweld , __ L-40 Del stub min. - ::;, I Dia meter as per calculations "{, ,,,111 fl l I ' e· min. r--- 18ft min. L---r--~ I---Alternatively, metal stakes _L Conc,ete base and wire may be used to pre\lent flotation > J--2x riser die. Min. -l Figure 4.26 -Sediment Pond Riser Detail February 2005 Volume II -Construction Stormwater Pollution Prevention 4-107 4-108 I i. ! 0 I a 0.1 1 HEAD IN FEET (meaoured from creat o! rl•••l 10 Q••k:9.739 DH 111 a.,1t1 .. i=3.782 D 2 H 1 n Q 11'1 els, D •nd H In 1eet Slope Change ccc:ura at weir-orifice trensltlon. Figure 4.27 -Riser Inflow Curves Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 Princi1ial Spillway: Detem1ine the required diameter for the principal spillway (riser pipe). The diameter shall be the minimum necessary to pass the pre-developed 10-ycar peak flow (Owl-Use Figure 4.28 to detenmne this diameter ('1 = I-foot). Note: A permanent cvntrol structure may be used instead ofa temporary riser. Emergency Overflow Spillway: Determine the required size and design of the emergency overflow spilJway for the developed I 00-ycar peak flow using the method contained in Volume III. Dewatering Orifice: Determine the size of the dewatering orifice(s) (minimum I-inch diameter) using a modified version of the discharge equation for a vertical orifice and a basic equation for the area of a circular orifice. Determine the required area of the orifice with the following equation: A, (2h)05 A = _ _c__-'-----'--- ' 0.6x3600Tg '" orifice area (square feet) pond surface area (square feet) where A 0 As h T g head of water above orifice (height of riser in feet) dewatering time (24 hours) acceleration of gravity (32.2 fcet/second 2) Convert the required surface area to the required diameter D of the orifice: 1A n~ 24x\/-" = 13 54x..rc . ff The vertical. perforated tubing connected to the dewatering orifice must be at least 2 inches larger in diameter than the orifice to improve flow characteristics. The size and number of perforations in the tubing should be large enough so that the tubing does not restrict flow. The orifice should control the flow rate. • Additional Design Specifications The pond shall be divided into two roughly equal volume cells by a penneable divider that will reduce turbulence while allowing movement of water between cells. The divider shall be at least one- half the height of the riser and a minimum of one foot below the top of the riser. Wire-backed, 2-to 3-foot high, extra strength filter fabric supported by treated 4"x4"s can be used as a divider. Alternatively, staked straw bales wrapped with filter fabric (geotextile) may be used. If the pond is more than 6 feet deep, a different mechanism must be proposed. A riprap embankment is one acceptable method of separation for deeper ponds. Other designs that satisfy the intent of Volume II -Construction Stormwater Pollution Prevention 4-109 Maintenance Standards 4-110 • this provision are allowed as long as the divider is penneable. structurally sound, and designed to prevent erosion under or around the barner. To aid in determining sediment depth, one-foot intervals shall be prominently marked on the riser. If an embankment of more than 6 feet is proposed, the pond must comply with the criteria contained in Volume Ill regarding dam safety for detention BMPs. The most common structural failure of sedimentation basins is caused by piping. Piping refers to two phenomena: ( 1) water seeping through fine-grained soil. eroding the soil grain by grain and fom1ing pipes or tunnels; and, (2) water under pressure Jlowing upward through a granular soil with a head of sufficient magnitude to cause s01l grains to lose contact and capability for support. The most critical construction sequences lo prevent piping will be: l. Tight connections between riser and barrel and other pipe connections. 2. Adequate anchoring of riser. 3. Proper sot! compaction of the embankment and riser footing. 4. Proper construction of anti-seep devices. • Sediment shall be removed from the pond when 11 reaches !-foot in depth. • Any damage to the pond embankments or slopes shall be repaired. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 4. 19 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. Design and Installation Specifications 4-94 • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a silt fence, rather than by a sediment pond, is when the area draining to the fence is one acre or less and flow rates are less than 0.5 cfs. • Silt fences should not be constructed in streams or used in V-shaped ditches. They are not an adequate method of silt control for anything deeper than sheet or overland flow. Joints in filter fabric shall be spliced at posts. Use staples, wire rings or equivalent to anach fabric to posts :/-- 2"x2" by 14 Ga. wire or equivalent, if standard __ ~ -strength fabric used :1-, ~ ' : Filter fabric----: I I '-{. -'T1~il~I =::il31:='I=: I ~-11--,::i-r-'·-~, i' _i"i:::.~,_1_:ic:.1 ' ,. ·-· ·--..... , cc:1,;=1cc--1---;,1- I ~---6' max -- / / Post spacing may be increased to 8' if wire backing is used ---....::-......_ -Minimum 4"x4" trench _ _,,,. .' \. Backfill trench with native soil "' or 3/4"-1.5" washed gravel ', 2"x2" wood posts, sleel fence posts, or equivalent Figure 4.19 -Silt Fence • Drainage area of I acre or less or in combination with sediment basin in a larger site. • Maximum slope steepness (normal (perpendicular) to fence line) I: I. • Maximum sheet or overland flow path length to the fence of 100 feet. • No flows greater than 0.5 cfs. • The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.10): Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 Table 4.10 Geotextile Standards ~~-------- Polymenc I\!esh AOS (ASTM D475 l) 0.60 mm maximum for slit film wovens (#30 sieve). 0.30 1 mm maximum for all other geotextile l)pes (#50 sieve). Water Pcm1itti\·ity I . '. (ASTM D4491) I -------·~-· Grab Tensile Strength (ASTM D4632) ,I Grab Tensile st·rength -- (ASTM D4632) Ultraviolet Resistance · (ASTM D4355) O. lS mm minimum for all fabric types (#100 sieve). · 0.02 sec.-1 minimum -J80·1b~~ Min~~~~1-:;:;-for--extra strength fclbric. : 100 lbs minimum for standard strength fabric 1 36% maximUrn - -I- I 70% minimum • Standard strength fabrics shall be supported with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are avai ]able that have synthetic mesh backing attached. • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construct10n life at a temperature range of0°F. to I 20°F. • 100 percent biodegradable silt fence is available that JS strong. long lasting, and can be left in place aficr the project is completed, if pem1itted by local regulations. • Standard Notes for construction plans and specifications follow. Refer to Figure 4.19 for standard silt fence details. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. The silt fences shall be constructed in the areas of clearing, grading, or drainage prior to starling those act1,it1es. A sill fence shall not be considered temporary if the silt fence must function beyond the life of the contract. The silt fence shall prevent soil carried by runoff water from going beneath, through. or over the top of the silt fence. but shall allow the water to pass through the fence. The minimum height of the top of silt fence shall be 2 feet and the maximum height shall be 2 'h feel above the original ground surface. The geotexlile shall be sewn together at the point of manufacture. or at an approved location as determined by the Engineer, to fonn geotextile lengths as required. All sewn seams shall be located at a support post. Alternatively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. Volume II -Construction Stormwater Pollution Prevention 4-95 4-96 The geotextile shall be attached on the up-slope side of the posts and support system with staples, wire, or in accordance with the manufacturer's recommendations. The gcotcxtilc shall be attached to the posts in a manner that reduces the potential for geotextile tearing at the staples, wire, or other connection device. Silt fence back-up support for the geotextile in the form of a wire or plastic mesh is dependent on the properties of the geotextile selected for use. lfwirc or plastic back-up mesh is used, the mesh shall be fastened securely to the up-slope of the posts with the geotextile being up-slope of the mesh back-up support. The gcotextile at the bottom of the fence shall be buried in a trench to a minimum depth of 4 inches below the ground surface. The trench shall be backfilled and the soil tamped in place over the buried portion of the gcotcxtile, such that no flow can pass beneath the fence and scouring can not occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the trench a minimum of 3 inches. The fence posts shall be placed or driven a minimum of I 8 inches. A minimum depth of 12 inches is allowed if topsoil or other soft subgrade soil is not present and a minimum depth of 1 8 inches cannot be reached. fence post depths shall be increased by 6 inches if the fence is located on slopes of3:1 or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. Silt fences shall be located on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowmg around the end of the fence. l f the fence must cross contours, with the exception of the ends of the fence, gravel check dams placed perpendicular to the back of the fence shall be used to minimize concentrated flow and erosion along the back of the fence. The "'rnvcl check dams shall be approximately I - foot deep at the back of the fence. It shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. The gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. The slope of the fence line where contours must be crossed shall not be steeper than 3: I. Wood, steel or equivalent posts shall be used. Wood posts shall have minimum dimensions of 2 inches by 2 inches by 3 feet minimum length, and shall be free of defects such as knots, splits, or gouges. Volume If -Construction Stormwater Pollution Prevention February 2005 February 2005 Steel posts shall consist of either size No. 6 rebar or larger, ASTM A 120 steel pipe with a minimum diameter of I -inch, U, T. L. or C shape steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts having equivalent strength and bending resistance to the post sizes listed. The spacing of the support posts shall be a maximum of6 feet. Fence back-up support, if used, shall consist of steel wire with a maximum mesh spacing of 2 inches. or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to ultraviolet radiation as the geotextile it supports. • Silt fence installation using the slicing method specification details follow Refer to Figure 4.20 for slicing method details. The base of both end posts must be at least 2 to 4 inches above the top of the silt fence fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet apart in standard applications. Install posts 24 inches deep on the downstream side of the silt fence. and as close as possible to the fabric, enabling posts to support the fabric from upstream water pressure. Install posts with the nipples facing away from the silt fence fabric. Attach the fabric to each post with three ties, all spaced within the top 8 inches of the fabric. Attach each tie diagonally 45 degrees through the fabric. with each puncture at least I inch vertically apart. In addition, each tie should be positioned to hang on a post nipple when tightening to prevent sagging. Wrap approximately 6 inches of fabric around the end posts and secure with 3 ties. No more than 24 inches of a 36-inch fabnc is allowed above ground level. The rope lock system must be used in all ditch check applications. The installation should be checked and corrected for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. Compaction is vitally important for effective results. Compact the soil immediately next to the silt fence fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Volume II -Construction Stormwater Pollution Prevention 4-97 /'1 aintenance Standards 4-98 • Any damage shall be repaired immediately. • If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a sediment pond. • It is important to check the uphill side of the fence for signs of the fence clogging and acting as a ban-ier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. • Sediment deposits shall either be removed when the deposit reaches approximately one-third the height of the silt fence, or a second silt fence shall be installed. • If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, It shall be re laced. Att.ach-lO oop .. t, • .,. ...... ., ..... ~t..ow- llf1n....-9adl.._., ••tr.-z••.._. ~ --e••--. ~ llllp.-.1.-..-~ I ,-..,~ POST SPACING: T iaa1t. ... .,. .. run• ..... __ ... ,..... ...... POliT DEPTH; ... _.. .... -...... • fllillortc ._ •"'"cl .............. _ ............ :"'""" i 1 .. CllagoNII e18cl!ment -- • ~ fabrle. poc,.. I' 1-o.d. -~-a'l-deganal)I, pund:Umg tdm-11caly II "**-1, a/ 1° llpBl'I. • H-v each 119 on e P*-nlppll, m1c1..-, ~- U. ~ 11e& ~ m ta1. wn. Roi of .. Janee SIi Fence --·""' compec1ion Vbatocy plow Is nae acceptable beceuse of horizontal compaction Figure 4.20 -Silt Fence Installation by Slicing Method Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C120: Temporary and Permanent Seeding Pwpose Conditions of Use Design u11d Installatio11 Specijicatio11s February 2005 Seeding is intended to reduce erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducmg erosion. • Seeding may be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. • Channels that will be vegetated should be installed before major earthwork and hydrosceded with a Bonded Fiber Matrix. The vegetation should be well established (i.e., 75 percent cover) before water is allowed to flow in the ditch. With channels that will have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannm be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch over hydromulch and blankets. • Retention/detention ponds should be seeded as required. • Mulch is required al all times because it protects seeds from heat, moisture loss, and transport due to runoff. • All disturbed areas shall be reviewed in late August to early September and all seed mg should be completed by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average protection. • At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and mulched. Final stabilization means the completion of all soil disturbing activities al the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions or geotextiles) which will prevent erosion. • Seedmg should be done during those seasons most conducive to growth and will vary with the climate conditions of the region. Local experience should be used to determine the appropriate seeding periods • The optimum seeding windows for western Washington are April I through June 30 and September I through Octoher 1. Seeding that occurs bct\vcen July 1 and August 30 will require inigat1on until 75 percent grass cover is established. Seeding that occurs between October I and March 30 will require a mulch or plastic cover until 75 percent grass cover ts established. • To prevent seed from being washed away, confirm that all required surface water control measures have been installed. Volume ff -Construction Stormwater Pollution Prevention 4-13 4-14 • The seedbed should be fim1 and rough. All soi I should be roughened no matter what the slope. If compaction is required for engineering purposes. slopes must be track walked before seeding. Backblading or smoothing of slopes greater than 4: I is not allowed if they arc to be seeded. • New and more effective restoration-based landscape practices rely on deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical the subgrade should be initially ripped to improve long-term permeability, infiltration, and water inflow qualities. At a minimum, permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that arc deeper than 8 inches the rototilling process should be done in multiple lifts, or the prepared soil system shall be prepared properly and then placed to achieve the specified depth. • Organic matter is the most appropriate form of ·'fertilizer" because it provides nutrients (including nitrogen, phosphoms, and potassium) in the least water-soluble fonn. A natural system typically releases 2-10 percent of its nutrients annually. Chemical fertilizers have since been formulated to simulate what organic matter does naturally. • In general, I 0-4-6 N-P-K (nitrogen-phosphoms-potassium) fertilizer can be used at a rate of90 pounds per acre. Slow-release fertilizers should always be used because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to detem1ine the exact type and quantity of fertilizer needed. This will prevent the over-application of fertilizer. Fertilizer should not be added to the hydromulch machine and agitated more than 20 minutes before it is to be used. If agitated too much, the slow-release coating is destroyed. • There are numerous products available on the market that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If I 00 percent cottonseed meal is used as the mulch in hydrosced, chemical fertilizer may not be necessary. Cottonseed meal is a good source of long-tem1, slow-release, available nitrogen. • Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. Mulch may be made up of 100 percent: cottonseed meal; fibers made of wood, recycled cellulose, hemp, and kenaf; compost; or blends of these. Tackifier shall be plant- based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 • :vlulch is always required for seeding. Mulch can be applied on top of the seed or simultaneously by hydroseeding. • On steep slopes. Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM) products should be used. BFM/MBFM products are applied at a minimum rate of 3,000 pounds per acre of mulch with approximately 10 percent tackifier. Application is made so that a minimum of 95 percent soil coverage is achieved. Numerous products are available commercially and should be installed per manufacturer's instructions. Most products require 24-36 hours to cure before a rainfall and cannot be installed on wet or saturated soils. Generally, these products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. BFMs and MBFMs have some advantages over blankets: • No surface preparation required: • Can be installed via helicopter in remote areas; • On slopes steeper than 2.5:1, blanket installers may need to be roped and harnessed for safety: • They are at least $1,000 per acre cheaper installed. In most cases, the shear strength of blankets is not a factor when used on slopes, only when used in channels. BFMs and MBFMs are good alternatives to blankets in most situations where vegetat10n establishment is the goal. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. One way to overcome this is to increase seed quantities by up to 50 percent. • Vegetation establishment can also be enhanced by dividing the hydromulch operation into two phases: I. Phase 1-Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift: 2. Phase 2-Install the rest of the mulch and tackifier over the first lift. An alternative is to install the mulch, seed, fertilizer, and tackifier in one lift. Then, spread or blow straw over the top of the hydromulch at a rate of about 800-l 000 pounds per acre. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: I. Irrigation 2. Reapplication of mulch 3. Repair of failed slope surfaces Volume II -Construction Stormwater Pollution Prevention 4-15 4-16 This technique works with standard hydromulch (1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). • Areas to be pe1111anently landscaped shall provide a healthy top soi I that reduces the need for fertilizers. improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. This can be accomplished in a number of ways: Recent research has shown that the best method to improve till soils is to amend these soils with compost. The optimum mixture is approximately two parts soil to one part compost. This equates to 4 inches of compost mixed to a depth of J 2 inches in till soils. Increasing the concentration of compost beyond this level can have negative effects on vegetal health, while decreasing the concentrations can reduce the benefits of amended soils. Please note: The compost should meet specifications for Grade A quality compost in Ecology Publication 94-038. Other soils, such as gravel or cobble outwash soils, may require different approaches. Organics and fines easily migrate through the loose strncture of these soils. Therefore, the importation of at least 6 inches of quality topsoil, underlain by some type of filter fabric to prevent the migration of fines, may be more appropriate for these soils. Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Areas that will be seeded only and not landscaped may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Native topsoil should be re-installed on the disturbed soil surface before application. • Seed that is installed as a temporary measure may be installed by hand if it will be covered by straw, mulch, or topsoil. Seed that is installed as a permanent measure may be installed by hand on small areas (usually less than I acre) that will be covered with mulch, topsoil, or erosion blankets. The seed mixes listed below include recommended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow- release fertilizers are used. Local suppliers or the local conservation district should be consulted for their recommendations because the appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. Volume If -Construction Stormwater Pollution Prevention February 2005 February 2005 Table 4.1 represents the standard mix for those areas where just a temporary vegetative cover is required. ~ Table4.1 Temnorarv Erosion Control Seed Mix % WeiPht % Puritv % Germination Chev,:ings or annual blue grass 40 98 90 Festuca rnbra wtr. commHtata or Poa anna .. ----~ ------------------- ' Perennial rye -50 98 90 -·------- 92 85 _ Lolium paenne ______ _ Redtop or colonial bentgrass 5 ----- 98 90 Agrosris alha or A_grostis ten_ui8 ______ _ White dutch clover 5 Trifolium renens Table 4.2 provides just one recommended possibility for landscaping seed. Table 4.2 Landscapinq Seed Mix % \.Vei!!ht % Pnrih" % Germination Perennial rye blen<l 70 98 90 Lolium pere1111c --------------··· -------------- Chnv1ngs and red fc:;cuc blend 30 98 90 Fcstuca rubrn 1•ar commutata or Festuca rnbra This turf seed mix in Table 4.3 is for dry situations where there is no need for much water. The advantage is that this mix reqmres very linle maintenance. Table 4.3 Low-Growino Turf Seed Mix Dwarf tall fescue ( several varieties) Fesruca ar·1mdinacPa var. Dwarf perennial rye (Barclay) . - 'Yo Wei1!'ht 45 ---·-- 30 %, Purity 98 98 I ____ 0}ji_l!!'.(.P_C!renne W!_: Jl.nn..:Jax __ ------ , Red fcscuc Fest11ca rnbm e----.,.----- Colonial bcntgrass AJ?rostis tenuis - 20 98 -· --- 5 98 % Germination 90 ---- 90 90 -·-- 90 Table 4.4 presents a mix recommended for bioswales and other intcm1ittently wet areas. Table 4.4 Bioswale Seed Mix' '!lo \\1eii:i:ht %, Puritv % Germination Tall or meadow fescue 75-80 98 90 Festuca arn11dinacea or Festuca elatior ----. --------. .. ------- Seaside/Creeping bentgrass I 0-15 92 85 A1rmstis pa_lustris . ______ . ----------·---- Redtop bentgrass 5-10 90 80 Aerostis alba or Ae:rostis gif!antea * Mod(fied Bnargreen. Inc. Hydroseeding Guide Wetlands Seed Mix Volume II -Construction Stormwater Pollution Prevention 4-17 Maintenance Standards 4-18 The seed mix shown in Table 4.5 is a recommended low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Other mixes may be appropriate, depending on the soil type and hydrology of the area. Recent research suggests that bentgrass (agrostis sp.) should be emphasized in wet-area seed mixes. Apply this mixture at a rate of 60 pounds per acre. Table 4.5 Wet Area Seed Mix• % Wei(Jhf % Purit"' % Germination Tall or meadow fescue 60-70 98 90 Festuca anmdinacea or Festuca elatiur . -----··· .. ------------------- Seaside/Creeping bentgrass 10-15 98 85 ~ /}grostis palus!}_·1~~---- !vfcadoVI.' foxtail 10-15 90 80 _ Alep_ocurus_pratensis ____ ------------- Alsike clover 1-6 98 90 --· _ Tri(olium hvbridrrm --------- Redtop bentgrass 1-6 92 85 Af.'rostis alba * ModUied Briargreen. Inc. Hydroset!ding GHide Wetlwuh Seed Mix The meadow seed mix in Table 4.6 is recommended for areas that will be maintained infrequently or not at all and where colonization by native plants is desirable. Likely applications include rural road and utility right- of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. The appropriateness of clover in the mix may need to be considered, as this can be a fairly invasive species. If the soil is amended, the addition of clover may not be necessary. Table 4.6 Meadow Seed Mix % ,vl'iPh{ 0/-0 Purih· %, Germination Redtop or Oregon bentgrass 20 92 85 Agros~i!!_u._{()_Q_ o_!_Jg1!J:~·l_(" w·'!.K_o1!!',1Sijj_ ---- Red fescue 70 98 90 Festuca ruhra -------------. ---------White dutch clover IO 98 90 Tri{olwm reJJen~ • Any seeded areas that fail to establish at least 80 percent cover ( 100 percent cover for areas that receive sheet or concentrated flows) shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding, mulching, or nets/blankets, shall be used_ If winter weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. Volume II -Construction Stormweter Pollution Prevention February 2005 February 2005 • After adequate cover is achieved, any areas that experience erosion shall be reseeded and protected by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area reseeded and protected by mulch. • Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes runoff. Volume II -Construction Stormwater Pollution Prevention 4-19 BMP C122: Nets and Blankets Purpose Conditions of Use 4-22 Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. ln addition. some nets and blankets can be used lo permanently reinforce turf to protect drainage ways during high flows. Nets ( commonly called matting) are strands of material woven into an open, but high-tensile strength net (for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead fonn a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 2H: IV or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales (highly recommended) The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized rnnoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due lo their open, porous strncture. Synthetic nets and blankets can be used to permanently stabilize channels and may provide a cost-effective. environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required; • On slopes steeper than 2.5: 1, blanket installers may need to be roped and harnessed for safety; • They cost at least $4,000-6,000 per acre installed. Advantages of blankets include: • Can be installed without mobilizing special equipment; • Can be installed by anyone with minimal training; • Can be installed in stages or phases as the project progresses; • Seed and fertilizer can be hand-placed by the installers as they progress down the slope; • Can be installed in any weather; • There are numerous types of blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. Volume II -Construction Stormwater Pollution Prevention February 2005 Design a11d lnsta/latio11 Specijicatio11s February 2005 • See Figure 4.4 and Figure 4.5 for typical orientation and installation of blankets used in channels and as slope protection Note: these are typical only; all blankets must be installed per manufacturer's installation instructions. • Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. • Installation of Blankets on Slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. :\JOTE: Staples are metal,"U"-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5 Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintam soil contact. In addition, no one is allowed to walk on the blanket after 11 is m place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, 1t is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engmeer consults the manufacturer's infonnation and that a site visit takes place in order to insure that the product specified is appropriate. Infonnation is also available at the followmg web sites: 1. WSDOT: http://www.wsdot.wa.gov/eesc/environmental/ 2. Texas Transportation Institute: http://www. dot state. tx. us/ insdtdot/ orgch art/ cmd/ erosion/ contents. htm Volume II -Construction Stormwater Pollution Prevention 4-23 Maintenance Standards 4-24 • Jute matting must be used in conjunction with mulch (BMP C 12 l ). Excelsior. woven straw blankets and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. • In general, most nets (e.g.,jute matting) require mulch in order to prevent erosion because they have a fairly open strucnire. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep, unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets. as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. • 100 percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. • Most netting used with blankets is photodegradable, meaning they break down under sunlight (not UV stabilized) However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. • Good contact with the ground must be maintained. and erosion must not occur beneath the net or blanket. • Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled. • If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area protected. Volume II -Construction Stormwater Pollution Prevention February 2005 Longitudinal Anchor Trench Terminal Slope and Channel Anchor Trench "'· • • • • • "' • • "' 'I,< • Initial Channel Anchor Trench 1n1ermi1tent Check Slot NOTES: 1. Check slots to be constructed per manufacturers spccifica.tiuns. 2. Sial::ing or slllp\ing layout per manufactuurs :;pc,cifieations. Figure 4.4 -Channel Installation Slope surface shall be smooth before placement for proper soil contact Stapling pattern as per manufacturer's recommendations Anchor in 6"x6" min_ Trench and staple at 12" intervals. Bring malerial down to a ~vel area, tum Do not stretch bl&nkets/mattings tight· allow the rOlls to mold to any Irregularities. the end under 4• and staple at 12" intervals. For slopes less than 3H: 1V, rolls may be placed in horizontal strips. Lime, fertilize, and seed before instanalion. Planting of shrubs, trees, etc. Should DCCUr after installation. Figure 4.5 -Slope Installation February 2005 Volume II -Construction Stormwater Pollution Prevention 4-25 BMP C123: Plastic Covering Pwpose Co11ditio11s of Use 4-26 Plastic co\'ering provides immediate, short-term erosion protection to slopes and disturbed areas. • Plastic CO\'ering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and till slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-tem1 (greater than six months) applications. • Clear plastic sheeting can be used over newly-seeded areas to create a greenhouse effect and encourage grass growth if the hydroseed was installed too late in the season to establish 75 percent grass cover, or if the wet season started earlier than nonnal. Clear plastic should not be used for this purpose during the summer months because the resulting high temperatures can kill the grass. • Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • . While plastic is inexpensive to purchase, the added cost of installation, maintenance, removal, and disposal make this an expensive material, up to S 1.50-2.00 per square yard. • Whenever plastic is used to protect slopes, water collection measures must be installed at the base of the slope. These measures include plastic-covered benns, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. At no time is clean runoff from a plastic covered slope to be mixed with diny runoff from a project. • Other uses for plastic include: I . Temporary ditch liner; 2. Pond liner in temporary sediment pond; 3. Liner for benned temporary fuel storage area if plastic is not reactive to the type of fuel being stored; 4. Emergency slope protection during heavy rains; and, 5. Temporary drainpipe ("elephant trunk'') used to direct water. Volume II -Construction Stormwater Pollution Prevention February 2005 Design and Installation Specifications l',fai11tena11ce Standards February 2005 • Plastic slope cover must be installed as follows: l. Run plastic up and down slope, not across slope: 2. Plastic may be installed perpendicular to a slope if the slope length is less than l O feet: 3. Minimum of 8-inch overlap at seams; 4. On long or wide slopes, or slopes subject to wind, all seams should be taped: 5. Place plastic into a small ( 12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath; 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and pound a wooden stake through each to hold them in place; 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity nmoff from contacting bare soil which causes extreme erosion; 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. • If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be inst a lied at the toe of the slope in order to reduce the velocity of runoff • Tom sheets must be replaced and open seams repaired. • If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and replaced. • When the plastic is no longer needed, it shall be completely removed. • Dispose of old tJres appropriately. Volume fl -Construction Stormwater Pollution Prevention 4-27 BMP C125: Topsoiling Purpose Conditions of Use Design and Installation Specifications February 2005 To provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling is an integral component of providing pemianent cover in those areas where there is an unsuitable soil surface for plant growth. Native soils and disturbed soils that have been organically amended not only retain much more stonnwater, but they also serve as effective biofilters for urban pollutants and. by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. • Native soils should be lcti undisturbed to the maximum extent practicable. Native soils disturbed during clearing and grading should be restored, to the maximum extent practicable, to a condition where moisture-holding capacity is equal to or better than the original site conditions. This criterion can be met by using on-site native topsoil, incorporating amendments into on-site soil, or importing blended topsoil. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. • Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. If an existing soil system is functioning properly it shall be preserved in its undisturbed and uncompacted condition. • Depending on where the topsoil comes from, or what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Commercially available mycorrhiza products should be used when topsoil is brought in from off-site. If topsoiling is to be done, the following items should be considered: • Maximize the depth of the topsoil wherever possible to provide the maximum possible infiltration capacity and beneficial growth medium. Topsoil depth shall be at least 8 inches with a minimum organic content of IO percent dry weight and pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. This can be accomplished either by returning native topsoil to the site and/or incorporating organic amendments. Organic amendments should be incorporated to a minimum 8-inch depth except where tree roots or other natural Volume II -Construction Stormwater Pollution Prevention 4-29 features limit the depth of incorporation. Subsoils below the 12-inch depth should be scarified at least 2 inches to avoid stratified layers. where feasible. The decision to either layer topsoil over a subgrade or incorporate topsoil into the underlying layer may vary depending on the planting specified. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, recent practices have shown that incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. • Allow sufficient time in scheduling for topsoil to be spread prior to seeding. sodding, or planting. • Care must be taken not to apply to subsoil if the two soils have contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. • If topsoil and subsoil are not properly bonded. water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. • Ripping or rc-structming the subgrade may also provide additional benefits regarding the overall infiltration and intcrflow dynamics of the soil system. • Field exploration of the site shall be made to dctermme if there is surface soil of sufficient quantity and quality to justify stnppmg. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, clay loam). Areas of natural ground water recharge should be avoided. • Stripping shall be confined to the immediate construction area. A 4-to 6-mch stripping depth is common, hut depth may vary depending on the particular soil. All surface runoff control strnctures shall be in place prior to stripping. Stockpiling of topsoil shall occur in the following manner: • Side slopes of the stockpile shall not exceed 2: 1. • An interceptor dike with gravel outlet and silt fence shall surround all topsoil stockpiles between October I and April 30. Between May 1 --------~ ---------------------------- 4-30 Volume II -Construction Stormwater Pollution Prevention February 2005 Jl,faintenance Standards February 2005 and September 30, an interceptor dike with gravel outlet and silt fence shall be installed if the stockpile will remain in place for a longer period of time than active construction grading. • Erosion control seeding or covering with clear plastic or other mulching materials of stockpiles shall be completed within 2 days (October I through April 30) or 7 days (May 1 through September 30) of the fomrntion of the stockpile. Native topsoil stockpiles shall not be covered with plastic. • Topsoil shall not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. , Previously established grades on the areas to be topsoiled shall be maintained according to the approved plan. , When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: I. Topsoil is to be re-installed within 4 to 6 weeks: 2. Topsoil is not to become sanirated with water; 3. Plastic cover is not allowed. , Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. Volume II -Construction Storm water Pollution Prevention 4-31 BMP C140: Dust Control Puipose Conditions of Use De.sign and Installatio11 Specifications 4-40 Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. • In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. • Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching, or paving is impractical, apply gravel or landscaping rock. • Lnnit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition, if stable. Maintain the original ground cover as long as practical. , Constrnct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. • Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to Stabilized Construction Entrance (BMP C105). , Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. , Spray exposed soil areas with a dust palliative, following the manufacturer's instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. , PAM (BMP Cl 26) added to water at a rate of0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to the increased infiltration of water into the soil and reduced evaporation. In addition. small soil particles are bonded together and are not as easily transported by wind. Adding PAM may actually reduce the quantity of waler needed for dust control, especially in eastern Washington. Since the wholesale cost of PAM is about$ 4.00 per pound, this is an extremely cost- effective dust control method. Techniques that can be used for unpaved roads and lots include: , Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. , Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. Volume II -Construction Stormwater Pollution Prevention February 2005 Maintenance Standards February 2005 • Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm) to 10 to 20 percent. • Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstmction. • Encourage the use of alternate, paved routes, if available. • Restrict use by tracked vehicles and heavy trncks to prevent damage to road surface and base. • Apply chemical dust suppressants using the admix method, blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. • Pave unpaved pem1anent roads and other trafficked areas. • Use vacuum street sweepers. • Remove mud and other dirt promptly so it docs not dry and then tum into dust. • Limit dust-causing work on windy days. • Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Respray area as necessary to keep dust to a minimum. Volume II -Construction Stormwater Pollution Prevention 4-41 4.2 Runoff Conveyance and Treatment BMPs BMP C200: Interceptor Dike and Swale Pu1pose Conditio11s of Use Design and Installation Specifications February 2005 Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site. Where the runoff from an exposed site or disturbed slope must be conveyed to an erosion control facility which can safely convey the stormwater. • • • • • • • • • • Locate upslope of a constmction site to prevent runoff from entering disturbed area. When placed horizontally across a disturbed slope, it reduces the amount and velocity of runoff flowing down the slope. Locate downslope to collect runoff from a disturbed area and direct it to a sediment basin. Dike and/or swale and channel must be stabilized with temporary or pennanent vegetation or other channel protection during constmction. Channel requires a positive grade for drainage; steeper grades reqnire channel protection and check dams. Review construction for areas where overtopping may occur. Can be used at top of new fill before vegetation is established . May be used as a pem1anent diversion channel to can-y the runoff Sub-basin tributary area should be one acre or less . Design capacity for the peak flow from a 10-year, 24-hour storm, assuming a Type 1 A rainfall distribution, for temporary facilities. A ltematively, use 1.6 times the 10-year, I -hour flow indicated by an approved continuous runoff model. For facil1t1es that will also serve on a pennanent basis, consult the local government's drainage requirements. Interceptor dikes shall meet the following criteria: Top Width 2 feet minimum. Height 1.5 feet minimum on berm. Side Slope 21 or flatter. Grade Depends on topography, however, dike system minimum is 0.5%, maximum is 1 %. Compaction Minimum of 90 percent ASTM D698 standard proctor. Volume II -Construction Stormwater Pollution Prevention 4-57 4-58 Horizontal Spacing of Interceptor Dikes: Average Slope 201-1: IV or Jess (10 to 20)H:1V (4to10)H:1V (2to4)H:JV Slope Percent 3-5% 5-10% 10-25% 25-50% Stabilization depends on velocity and reach Flowpath Length 300 feel 200 feet I 00 feet 50 feet Slopes <5% Seed and mulch applied within 5 days of dike construction (see BMP CI 21, Mulching). Slopes 5 -40% Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion. , The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall occur at the outlet. Provide energy dissipation measures as necessary. Sediment-laden nmoffmust be released through a sediment trapping facility. , Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. Interceptor swales shall meet the following criteria: Bottom Width 2 feet minimum; the bottom shall be level. Depth I-foot minimum. Side Slope 2: I or flatter. Grade Maximum 5 percent, with positive drainage to a suitable outlet (such as a sediment pond). Stabilizallon Seed as per BMP Cl 20, Te1i1porary and Permanent Seeding, or BMP C202, Channel Lining, 12 inches thick of riprap pressed into the bank and extending at least 8 inches vertical from the bottom. , Inspect diversion dikes and interceptor swales once a week and after every rainfall. Immediately remove sediment from the flow area. , Damage caused by construction traffic or other activity must be repaired before the end of each working day. Check outlets and make timely repairs as needed to avoid gully fonnation. When the area below the temporary diversion dike is pe1manently stabilized, remove the dike and fill and stabilize the channel to blend with the natural surface. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C201: Grass-Lined Channels Purpose Co11ditio11s of Use Design and lllstallatio11 Specifications February 2005 To provide a channel with a vegetative I ining for conveyance of runoff. See Figure 4.7 for typical grass-lined channels. This practice applies to construction sites where concentrated runoff need: to be contained to prevent erosion or flooding. • When a vegetative lining can provide sufficient stability for the channel cross section and at lower velocities of water (norrnaJly dependent on grade). This means that the channel slopes are generaJly Jess than 5 percent and space is available for a relatively large cross section. • Typical uses include roadside ditches, channels at property boundaries, outlets for diversions, and other channels and drainage ditches in low areas. , Channels that will be vegetated should be installed before major earthwork and hydroseeded with a bonded fiber matrix (BFM). The vegetation should be well established (i.e., 75 percent cover) before water is aJlowed to flow in the ditch. With channels that wiJI have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch in lieu of hydromulch and blankets. Locate the channel where it can conform to the topography and other features such as roads. • Locate them to use natural drainage systems to the greatest extent possible. • Avoid sharp changes in alignment or bends and changes in grade. , Do not reshape the landscape to fit the drainage channel. • The maxnnum design velocity shaJI be based on soil conditions. type of vegetation, and method of rcvegetation, but at no !Imes shall velocity exceed 5 fectisecond. The channel shall not be overtopped by the peak runoff from a 10-year, 24-hour stmm, assuming a Type lA rainfall distribution." Alternatively, use 1.6 times the 10-year, ] -hour flow indicated by an approved continuous runoff model to detemirne a flow rate which the channel must contain. • Where the grass-lined channel will also function as a pe1manent storrnwater conveyance facility, consultant the drainage conveyance requirements of the local government with jurisdiction. • An established grass or vegetated lining is required before the channel can be used to convey storrnwater, unless stabilized with nets or blankets. Volume II -Construction Stormwater Pollution Prevention 4-59 Maintenance Standard, 4-60 • If design velocity of' a channel to be vegetated by seeding exceeds 2 ftisec, a temporary channel liner is required. Geotextile or special mulch protection such as fiberglass roving or straw and netting provide stability until the vegetation is fully established. Sec Figure 4.9. • Check dams shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • If vegetation is established by sodding, the pennissible velocity for established vegetation may be used and no temporary liner is needed. , Do not subject grass-lined channel to sedimentation from disturbed areas. Use sediment-trapping BMPs upstream of the channel. • V-shapcd grass channels generally apply where the quantity of water is small, such as in short reaches along roadsides. The V-shaped cross section is least desirable because it is difficult to stabilize the bottom where velocities may be high. , Trapezoidal grass channels are used where nmoff volumes are large and slope is low so that velocities are nonerosive to vegetated linings. (Note: it is difficult to construct small parabolic shaped channels.) • Subsurface drainage, or riprap channel bottoms, may be necessary on sites that are subject to prolonged wet conditions due to long duration flows or a high water table. , Provide outlet protection at culvert ends and at channel intersections. • Grass channels, at a minimum. should carry peak nm off for temporary construction drainage facilities from the 10-year, 24-hour storm without eroding. Where flood hazard exists, increase the capacity according to the potential damage. , Grassed channel side slopes generally arc constructed 3: I or flatter to aid in the establishment of vegetation and for maintenance. , Construct channels a minimum of 0.2 foot larger around the periphery to allow for soil hulking during seedbed preparations and sod buildup. During the establishment period, check grass-lined channels after every rainfall. , After grass is established, periodically check the channel; check it after every heavy rainfall event. Immediately make repairs. • It is particularly important to check the channel ontlet and all road crossings for bank stability and evidence of piping or scour holes. • Remove all significant sediment accumulations to maintain the designed carrying capacity. Keep the grass in a healthy, vigorous condition at all times, since it is the primary erosion protection for the channel. Volume II -Construction Stormwater Pollution Prevention February 2005 Typical V-Shaped Channel Cross-section L____ Grass-Lined Typical Parabolic Channel Cross-Section Typical Trapezoidal Channel Cross-Section Figure 4.8 -Typical Grass-Lined Channels February 2005 Volume II -Construction Stormwater Pollution Prevention 4-61 1 Overlap 6" (150mm) minimum \ \ \ OVERCUT CHANNEL 2· (50mm) TO ALLOW BULKING OUR/NG SEEOBEO PREPARATION Excavate Channel to Design Grade and Cross Section Design Depth ,,; 1\\,/, ,\\J ,V, , I, TYPICAL INSTALLATION WITH EROSION CONTROL BLANKETS OR TURF REINFORCEMENT MATS Intermittent Check Slot Longitudinal Anchor Trench Shingle-lap spliced ends or begin new roll in an intermittent check slot NOTES: 1. Design velocities exceeding 2 ft/sec (0.5rn/sec) require temporary blankets, mats or similar liners to protect seed and soil until vegetation becomes established. 2. Grass-lined channels with design velocities exceeding 6 ft/sec (2mlsec) should include turfreinforcement mats. Figure 4.9 -Temporary Channel Liners 4-62 Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C204: Pipe Slope Drains Puipose To use a pipe to convey stonnwater anytime water needs to be diverted away from or over bare soil to prevent gullies, channel erosion, and saturation of slide-prone soils. Conditions of Use Pipe slope drains should be used when a temporary or permanent stom1water conveyance is needed to move the water down a steep slope to avoid erosion (Figure 4.10). February 2005 On highway projects, they should be used at bridge ends to collect nmoff and pipe it to the base of the fill slopes along bridge approaches These can be designed into a project and included as bid items. Another use on road projects is to collect runoff from pavement and pipe it away from side slopes. These are useful because there is generally a time lag between having the first I ift of asphalt installed and the curbs, gutters, and pemianent drainage installed. Used in conjunction with sand bags, or other temporary diversion devices, these will prevent massive amounts of sediment from leaving a project. Water can be collected, channeled with sand bags, Triangular Silt Dikes, berms, or other material, and piped to temporary sediment ponds. Pipe slope drains can be: • Connected to new catch basins and used temporarily until all pcm1ancnt piping is installed; • Used to drain water collected from aquifers exposed on cut slopes and take it to the base of the slope; • Used to collect clean mnoff from plastic sheeting and direct it away from exposed soil: • Installed in conjunction with silt fence to drain collected water to a controlled area; • Used to divert small seasonal streams away from construction. They have been used successfully on culvert replacement and extension jobs. Large flex pipe can be used on larger streams during culvert removal, repair, or replacement; and, • Connected to existing down spouts and roof drains and used to divert water away from work areas during building renovation, demolition, and constmction projects. There are now several commercially available collectors that are attached to the pipe inlet and help prevent erosion at the inlet. Volume II -Construction Stormwater Pollution Prevention 4-67 Design and btstal/ation Specifications 4-68 Size the pipe to convey the flow. The capacity for temporary drains shall b, sufficient to handle the peak flow from a I 0-year, 24-hour storm event, assuming a Type l A rainfall distribution. Alternatively, use 1.6 times the l 0-year, I -hour flow indicated by an approved continuous runoff model. Consult local drainage requirements for sizing permanent pipe slope drains. • Use care in clearing vegetated slopes for installation. • Re-establish cover immediately on areas disturbed by installation. • Use temporary drains on new cut or fill slopes. • Use diversion dikes or swales lo collect water at the lop of the slope. • Ensure that the entrance area is stable and large enough to direct flow into the pipe. • Piping of water through the berm at the entrance area is a common failure mode. • The entrance shall consist of a standard flared end section for culverts 12 inches and larger with a minimum 6-inch metal toe plate to prevent runoff from undercutting the pipe inlet. The slope of the entrance shall be at least 3 percent. Sand hags may also be used at pipe entrances as a temporary measure. • The soil around and under the pipe and entrance section shall be thoroughly compacted lo prevent undercutting. • The flared inlet section shall be securely connected to the slope drain and have watertight connecting bands. • Slope drain sections shall he securely fastened together, fused or have gasketed watertight fittings, and shall be securely anchored into the soil. • Thrust blocks should be installed anytime 90 degree bends are utilized. Depending on size of pipe and flow, these can be constructed with sand bags, straw bales staked in place, "t" posts and wire, or ecology blocks. • Pipe needs to be secured along its full length to prevent movement. This can be done with steel "t" posts and wire. A post is installed on each side of the pipe and the pipe is wired to them. This should be done every 10-20 feet of pipe length or so, depending on the size of the pipe and quantity of water to diverted. • Interceptor dikes shall be used to direct nmoff into a slope drain. The height of the dike shall be at least I foot higher at all points than the top of the inlet pipe. • The area below the outlet must be stabilized with a riprap apron (see BMP C209 Outlet Protection, for the appropriate outlet material). Volume II -Construe/ion Stormwater Pollution Prevention February 2005 Maintenance Standards February 2005 • If the pipe slope drain is conveying sediment-laden water, direct all flows into the sediment trapping facility. • Materials specifications for any permanent piped system shall be set by the local government. Check inlet and outlet points regularly, especially after storms. The inlet should be free of undercutting, and no water should be going around the point of entry. If there are problems, the headwall should be reinforced with compacted earth or sand bags. • The outlet point should be free of erosion and installed with appropriate outlet protection. • For permanent installations, inspect pipe periodically for vandalism and physical distress such as slides and wind-throw. • Normally the pipe slope is so steep that clogging is not a problem with smooth wall pipe, however, debris may become lodged in the pipe. CPEP or equivalent pipe Discharge to a stabilized watercourse, sediment retention facility, or stabilized outlet Provide ri_prap pad or equivalent energy dissipation ( Interceptor Dike Standard flared end section tnlet and all sections must be securely fastened together with gasketed watertight fittings Figure 4.10 -Pipe Slope Drain Volume II -Construction Stonnwater Pollution Prevention 4-69 BMP C208: Triangular Silt Dike (Geotextile-Encased Check Dam) Pmpose Conditions of use Design a11d l11stal/ation Specifications Maintenance Standards 4-78 Triangular silt dikes may be used as check dams, for perimeter protection, for temporary soil stockpile protection, for drop inlet protection, or as a temporary interceptor dike. May be used in place of straw bales for temporary check dams in ditches of any dimension. • May be used on soil or pavement with adhesive or staples. • TSDs have been used to build temporary: I . sediment ponds; 2. diversion ditches; 3. concrete wash out facilities; 4. curbing; 5. water bars; 6. level spreaders; and. 7. berms. Made of urethane foam sewn into a woven geosynthetic fabric. It is triangular, 10 inches to 14 inches high in the center, with a 20-inch to 28-inch base. A 2~foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at one end allows attachment of additional sections as needed. • Install with ends curved up to prevent water from flowing around the ends. • The fabric flaps and check dam units are attached to the ground with wire staples. Wire staples should be No. I I gauge wire and should be 200 mm to 300 mm in length. • When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting unit and be stapled. • Check dams should be located and installed as soon as construction will allow. • Check dams should be placed perpendicular to the flow of water. • When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot and staples. • In the case of grass-lined ditches and swales, check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Triangular silt dams shall be monitored for performance and sediment accumulation during and after each runoff producing rainfall. Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 Sediment shall be removed when it reaches one half the height of the dam. • Anticipate submergence and deposition above the triangular silt dam and erosion from high flows around the edges of the dam. Immediately repair any damage or any undercutting of the darn. Volume ff -Construction Stormwater Pollution Prevention 4-79 BMP C220: Storm Drain Inlet Protection Purpose Conditions of Use Type of Inlet Protection To prevent coarse sediment from entering drainage system·s prior to pennanent stabilization of the disturbed area. Where stonn drain inlets are to be made operational before pem1anent stabilization of the disturbed drainage area. Protection should be provided for all stom1 drain inlets downslope and within 500 feet of a disturbed or constrnction area, unless the runoff that enters the catch basin will be conveyed to a sediment pond or trap. lnlet protection may be used anywhere to protect the drainage system. It is likely that the drainage system will still require cleaning. Table 4.9 lists several options for inlet protection. All of the methods for stonn drain inlet protection are prone to plugging and require a high frequency of maintenance. Drainage areas should be limited to 1 acre or less. Emergency overflows may be required where stonnwater ponding would cause a hazard. 1f an emergency overflow is provided, additional end-of-pipe treatment may be required. Table 4.9 Storm Drain Inlet Protetion Applicable for Emergency Paved/ Earthen Overflow Surfaces Conditions of Use Dron Inlet. Protection Excavated drop inlet Yes. protection temporary flooding will occur Block and gravel drop Ye.s inlet protection Gravel and wire drop No inlet protection Catch basin filters Yes Curb Inlet Protection 1 Curb inlet protection Small capacity with a wooden weir overflow 1 Block and grave] curb Yes I. inlet protection Culvert Inlet Protection Culvert inlet sediment t.ra Earthen Applicable for heavy flows. Easy to maintain. Large area Requirement: 30' X 30'/acre Paved or Earthen Applicable for heavy coneentrated flows. Will not pond. Applicable for heavy concentrated flows. Will pond. Can withstand traffic. Paved or Earthen Freouent maintenance renuired. Paved Used for sturdy, more compact installation. Paved Sturdy, but limited filtration. 18 month expected life. 4-82 Volume II -Construction Stormwater Pollution Prevention February 2005 I I Design and Installation Specifications February 2005 Exca\'C/ted Drop Inlet Protection -An excavated impoundment around the storn1 drain. Sediment settles out of the storn1water prior to entering the stonn drain. • Depth 1-2 ft as measured from the crest of the inlet structure. • Side Slopes of excavation no steeper than 2: I. • Minimum volume of excavation 3 5 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing stmcture and stabilizing area. • It may be necessary to build a temporary dike to the down slope side of the stmcrure to prevent bypass flow. Block and Gral'ei Filter -A barrier fanned around the stonn drain inlet with standard concrete blocks and gravel. Sec Figure 4.14. • Height 1 to 2 feet above inlet. • Recess the first row 2 inches into the ground for stability. • Support subsequent courses by placmg a 2x4 through the block opemng. • Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pool. • Place hardware cloth or comparable wire mesh with 1/,-inch openings over all block openmgs. • Place gravel just below the top of blocks on slopes of2:1 or flatter. • An alternative design is a gravel donut. • lnletslopeof3:l. • Outlet slope of 2: 1. • !-foot wide level stone area between the stmcture and the inlet. • Inlet slope stones 3 inches in diameter or larger. • Outlet slope use gravel Y,-to %-inch at a minimum thickness of ]-foot. Volume II -Construction Stormwater Pollution Prevention 4-83 4-84 Notes: Plan View Drain Grate Section A-A -A Drop Inlet Wire Screen or Filter Fabric 1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure. Figure 4.14 -Block and Gravel Filter Gravel and Wire Mesh Filter -A gravel barrier placed over the top of the inlet. This structure does not provide an overflow. • Hardware cloth or comparable wire mesh with Yi-inch openings. • Coarse aggregate. • Height I -foot or more, 18 inches wider than inlet on all sides. • Place wire mesh over the drop inlet so that the wire extends a minimum of I-foot beyond each side of the inlet structure. • If more than one strip of mesh is necessary, overlap the strips. • Place coarse aggregate over the wire mesh. • The depth of the gravel should be at least 12 inches over the entire inlet opening and extend at least 18 inches on all sides. Volume If -Construction Stormwater Pollution Prevention February 2005 February 2005 Cate hbasi11 Filters -Inserts should be designed by the manufacturer for use at construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. The maintenance requirements can be reduced by combining a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of- way. • 5 cubic feet of storage. • Dewatering provisions. • High-flow bypass that will not clog under normal use at a constrnction site. • The catchbasin filter rs inserted in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir -Barrier formed around a curb inlet with a wooden frame and gravel. • • • • • • Wire mesh with 'h-inch openings . Extra strength filter cloth . Construct a frame . Attach the wire and filter fabric to the frame . Pile coarse washed aggregate against wire/fabric . Place weight on frame anchors . Block a11d Grai-e/ Cw·b lnir:t Protection Barrier fonned around an inlet with concrete blocks and gravel. See Figure 4.14. • Wire mesh with 'h-inch openings. • Place two concrete blocks on therr sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pi le coarse aggregate against the wire to the top of the bani er. Curb and Gutter Sediment Barrier --Sandbag or rock berm (riprap and aggregate) 3 feet !ugh and 3 feet wide in a horseshoe shape. Sec Figure 4.16. • Construct a horseshoe shaped berm, faced with coarse aggregate if using 1iprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culver1 inlet. Volume II -Construction Stormwater Pollution Prevention 4-85 Maintenance Standards 4-86 • Catch basin filters should be inspected frequently, especially after stonn events. If the in sett becomes clogged, it should be cleaned or replaced. • For systems using stone filters: If the stone filter becomes clogged with sediment, the stones must be pulled away from the inlet and cleaned or replaced. Since cleaning of gravel at a construction site may be difficult, an alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into stonn drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. Volume II -Construction Stormwater Pollution Prevention February 2005 Plan View C Back of Sidewalk Section A -A NOTES: %" Drain Gravel (20mm) Wire Screen or Filter Fabric 4 Wood Stud (100x50 Tlmber Stud) Catch Basin Concrete Block Concrete Block Curb Inlet l Catch Basin 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Figure 4.15 -Block and Gravel Curb Inlet Protection February 2005 Volume II -Construction Stormwater Pollution Prevention 4-87 Plan View -------c Back of Sidewalk Burlap Sacks to :•r ~rO~•••-Dam RUNOFF RUNOFF NOTES: I. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow sediment to separate from runoff 2. Sandbag.s of either burlap or. woven 'geotextile' fabric, are filled with gravel, layered and packed tightly. 3. Leave a one sandbag gap in the top row to provide a spillway for overflow. 4. Inspect barriers and remove sediment after each storm event. Sediment and gravel mus1 be removed from the traveled way immediately. Fi ure 4.16 -Curb and Gutter Barrier 4-88 Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C202: Channel Lining Purpose Conditions of Use Design and Installation Specifications February 2005 To protect erodible channels by providing a channel liner using either blankets or riprap. When natural soils or vegetated stabilized soils in a channel are not adcquat, to prevent channel erosion. • When a permanent ditch or pipe system is to be installed and a temporary measure is needed. • In almost all cases, synthetic and organic coconut blankets are more effective than riprap for protecting channels from erosion. Blankets can be used with and without vegetation. Blanketed channels can be designed to handle any expected flow and longevity requirement. Some synthetic blankets have a predicted life span of 50 years or more. even in sunlight. • Other reasons why blankets are better than rock include the availability of blankets over rock. In many areas of the state, rock is not easily obtainable or is very expensive to haul to a site. Blankets can be delivered anywhere. Rock requires the use of dump trucks to haul and heavy equipment to place. Blankets usually only require laborers with hand tools, and sometimes a backhoe. • The Federal Highway Administration recommends not using flexible liners whenever the slope exceeds 10 percent or the shear stress exceeds 8 lbs/ft 2 See BMP C 122 for infonnation on blankets. Since riprap is used where erosion potential 1s high, construction must be sequenced so that the riprap is put in place with the minimum possible delay. • Disturbance of areas where riprap is to be placed should be undertaken only when final preparation and placement of the riprap can follow nnmcdiately behind the initial disturhance. Where riprap 1s used for outlet protection, the riprap should be placed before or in conjunction with the construction of the pipe or channel so that it 1s 111 place when the pipe or channel begins to operate. • The designer, after determining the riprap size that will be stable under the flow conditions, shall consider that size to be a minimum size and then, based on nprap gradations actually available in the area, select the size or sizes that equal or exceed the minimum size. The possibility of drainage structure damage by children shall be considered in selecting a riprap size, especially if there is nearby water or a gully in which to toss the stones. • Stone for riprap shall consist of field stone or quarry stone of approximately rectangular shape. The stone shall be hard and angular and of such quality that it will not disintegrate on exposure to water or Volume II -Construction Stormwater Pollution Prevention 4-63 4-64 weathering and it shall be suitable in all respects for the purpose intended. • Rubble concrete may be used provided it has a density of at least 150 pounds per cubic foot, and otherwise meets the requirement of this standard and specification. • A lining of engineering filter fabric (geotextile) shall be placed between the riprap and the underlying soil surface to prevent soil movement into or thrnugh the riprap. The geotextile should be keyed in at the top of the bank. • Filter fabric shall not be used on slopes greater than 1-1/2: I as slippage may occur. It should be used in conjunction with a layer of coarse aggregate (granular filter blanket) when the riprap to be placed is 12 inches and larger. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C209: Outlet Protection Puipose Co11ditions of use Design and Installation Specifications 4-80 Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stonnwater flows. Outlet protection is required at the outlets of all ponds. pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade drainage feature such as a stream, wetland. lake, or ditch. The receiving channel at the outlet of a culvert shall be protected from erosion by rock lining a minimum of 6 feet downstream and extending up the channel sides a minimum of \-foot above the maximum tail water elevation or l -foot above the crown, whichever is higher. For large pipes (more than 18 inches in diameter), the outlet protection lining of the channel is lengthened to four times the diameter of the culvert. • Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through WSDOT Engineering Publicat10ns) • Organic or synthetic erosion blankets, with or without vegetation, are usually more effective than rock, cheaper. and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can choose the correct material for the expected now. • With low flows, vegetation (including sod) can be effective. • The following guidelines shall be used for riprap outlet protection: l. If the discharge velocity at the outlet is less than 5 fps (pipe slope less than I percent), use 2-inch to 8-inch riprap. Minimum thickness is I -foot. 2. For 5 to 10 fps discharge velocity at the outlet (pipe slope less than 3 percent), use 24-inch to 4-foot riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), an engmecrcd energy dissipater shall be used. • Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. • New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be created by constructing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over- widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during Volume II -Construction Stormwater Pollution Prevention February 2005 I Mainte11a11ce Standards February 2005 high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. See Volume V for more information on outfall system design. • Inspect and repair as needed. • Add rock as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. Volume II -Construe/ion Stormwater Pollution Prevention 4-81 BMP C151: Concrete Handling Purpose Co11ditio11s of Use Design a11d lnstal/atio11 Specificatio11s Mai11te11a11ce Standards February 2005 Concrete work can generate process water and sluny that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. This BMP is intended to minimize and eliminate concrete process water and sluny from entering waters of the state, Any time concrete is used, these management practices shall be utilized. Concrete construction projects include, but are not limited to, the followmg • Curbs • Sidewalks • Roads • Bridges • Foundations • Floors • Runways • Concrete truck chutes, pumps, and internals shall be washed out only into fanned areas awaiting installation of concrete or asphalt • Cnused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling, • Hand tools including, but not ltmited to, screeds, shovels. rakes, floats, and trowels shall be washed off only into fanned areas awaiting installation of concrete or asphalt • Equipmem that cannot be easily moved, such as concrete pavcrs, shall only be washed 111 areas that do not directly dram to natural or constructed stormwater conveyances. • Washdown from areas such as concrete aggregate driveways shall not dram directly to natural or constructed storn1water conveyances. • When no fanned areas are available, washwater and leftover product shall be contained 111 a lined container. Contained concrete shall be disposed of in a manner that docs not violate groundwater or surface water quality standards. Containers shall be checked for holes in the liner daily during concrete pours and repaired the same day. Volume fl -Construction Stormwater Pollution Prevention 4-43 I BMP C152: Sawcutting and Surfacing Pollution Prevention Pu1pose Conditions of Use Design and Installation Specifications Maintenance Standards Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting), both of which can violate the water quality standards in the receiving water. This BMP is intended to minimize and eliminate process water and slurry from entering waters of the State. Anytime sawcutting or surfacing operations take place, these management practices shall be utilized. Sawcutting and surfacing operations include. but are not limited to, the following: • Sawing • Coring • Grinding • Roughening • Hydro-demolition • Bridge and road surfacing • Slurry and cuttings shall be vacuumed during cutting and surfacing operations. , SlutTy and cuttings shall not remain on pcnnanent concrete or asphalt pavement overnight. • Slu!Ty and cuttings shall not drain to any natural or constrncted drainage conveyance. , Collected slll!TY and cuttings shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Process water that is generated during hydro-demolition, surface roughening or similar operations shall not drain to any natural or constructed drainage conveyance and shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Cleaning waste material and demolition debris shall be handled and disposed ofin a manner that does not cause contamination of water. If the area is swept with a pick-up sweeper, the material must be hauled out of the area to an appropriate disposal site. Continually monitor operations to detennine whether slu!T)I, cuttings, or process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as benns, barriers, secondary containment, and vacuum trucks. -------------------~ ---~--- 4-44 Volume II -Construction Slormwater Pollution Prevention February 2005 Stormwater Pollution Prevention Plan Appendix C -Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element No. 1 -Mark Clearing Limits BMP C102: Buffer Zones BMP C104: Stake and Wire Fence Element No. 2 -Establish Construction Access BMPCI06: Wheel Wash BMP C 107: Construction Road/Parking Area Stabilization Element No. 3 -Control Flow Rates BMP C240: Sediment Trap Element No. 4 -Install Sediment Controls BMP C230: Straw Bale Barrier BMP C231: Brush Barrier BMP C232: Gravel Filter Berm BMP C234: Vegetated Strip BMP C235: Straw Wattles BMP C240: Sediment Trap Advanced BMPs: BMP C250: Construction Stormwater Chemical Treatment BMP C251: Construction Stormwater Filtration Element No. 5 -Stabilize Soils BMP C121: Mulching BMP C124: Sodding BMP C 126: Polyacrylamide for Soil Erosion Protection BMP Cl 30: Surface Roughening BMP C 131: Gradient Terraces BMP C 180: Small Project Construction Storm water Pollution Prevention Element No. 6 -Protect Slopes BMP C120: Temporary and Permanent Seeding BMP C 130: Surface Roughening BMP C 131 : Gradient Terraces BMP C205: Subsurface Drains BMP C206: Level Spreader BMP C207: Check Dams 25 Stormwater Pollution Prevention Plan Appendix D-General Permit 27 I I I I I I I I I I I I I I I I I I I Stormwater Pollution Prevention Plan Appendix E -Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. C. d. e. f. g. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. locations of BMPs inspected, 11. locations of BMPs that need maintenance, iii. the reason maintenance is needed, 1v. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. A description of any water quality monitoring performed during inspection, and the results of that monitoring. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. 29 h. Stormwater Pollution Prevention Plan A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. 1. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. 30 I I I I I I I I I I I I I I I I I I I Stormwater Pollution Prevention Plan Site Inspection Form General Information Project Name: Inspector Name: Title: CESCL#: Date: Time: Inspection Type: o After a rain event o Weekly o Turbidity/transparency benchmark exceedance o Other Weather Precipitation Since last inspection Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location BMP: Location Inspected Functioning YN IYNNIP Inspected y N Functioning I Y N NIP Element 2: Establish Construction Access BMP: Location BMP: Location Inspected y N Inspected y N Functioning IY N NIP Functioning IYN NIP 31 In last 24 hours Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Element 3: Control Flow Rates BMP: Location BMP: Location Inspected Functioning y N IY N NJP Inspected y N Functioning I Y N NJP Element 4: Install Sediment Controls BMP: Location BMP: Location BMP: Location BMP: Location BMP: Location Inspected Functioning y N IY N NJP Inspected Functioning YN IYNNJP Inspected y N Inspected y N Inspected y N Functioning IYN NJP Functioning I y N NJP Functioning I Y N NJP 32 Stormwater Pollution Prevention Plan Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Element 5: Stabilize Soils BMP: Location BMP: Location BMP: Location BMP: Location Inspected y N Functioning IY N NIP Inspected Functioning YN IYNNIP Inspected Functioning YN IYNNIP Inspected Functioning YN IYNNIP Element 6: Protect Slopes BMP: Location BMP: Location BMP: Location Inspected y N Functioning IY N NIP Inspected Functioning YN IYNNIP Inspected Functioning YN IYNNIP 33 Stormwater Pollution Prevention Plan Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Element 7: Protect Drain Inlets BMP: Location Inspected Functioning Y N IY N NIP BMP: Location Inspected Functioning YN IYNNIP BMP: Location Inspected Functioning YN IYNNIP Element 8: Stabilize Channels and Outlets BMP: Location BMP: Location BMP: Location BMP: Location Inspected y N Inspected y N Inspected y N Inspected y N Functioning IY N NIP Functioning I Y N NIP Functioning IYN NIP Functioning I Y N NIP 34 Stormwater Pollution Prevention Plan Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Element 9: Control Pollutants BMP: Location Inspected Functioning y N IY N NIP BMP: Location Inspected Functioning YN IYNNIP Element 10: Control Dewatering BMP: Location Inspected Functioning Y N IY N NIP BMP: Location Inspected Functioning YN IYNNIP BMP: Location Inspected Functioning YN IYNNIP Stormwater Pollution Prevention Plan Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Problem/Corrective Action Stormwater Discharges From the Site Observed? Problem/Corrective Action Y[Ej Location Turbidity E±j Discoloration Sheen Location Turbidity Discoloration Sheen 35 Stormwater Pollution Prevention Plan Water Oualitv Monitorinl! Was any water quality monitoring conducted? 0 Yes 0 No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? 0 Yes 0 No -If Ecology was notified, indicate the date, time, contact name and phone number below: Date: Time: Contact Name: Phone#: General Comments and Notes Include BMP reoairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? D Yes 0 No If photos taken, describe nhotos below: 36 Stormwater Pollution Prevention Plan Appendix F -Engineering Calculations 37 I I I I I I I I I I I I I I I I I I I sheet no project Consulting Engineers job no 1601 5/hAvenvc, Swte 1600 Seattle, WA 98101 (206) 622-5822 Fax (206) 622-8130 cl,en1 ~13.__------+-------.j ,r~ 1n SA = z ( Q., IS•NIN) O.OC>C>'G 54 = z. ( o.t:t4-7 eFs) c ,,,73 ~F c;. oco,e.. 13L ~ 'it. -2 I gkl = Tw -Z I {ft Yfc..J) ,..1973 1" L/4(1JJ -: 3 !(1W)1. .. ,cr73 . fW=~S.c,,(1.-~ 7~,'I) 8W=~.e,t:,, SL= SS.'I ~: (~s.r;.+11:.r.s) · 7e..., + ss.~ )( ~.s ') ~ '2 Vs~~SZ3 e-r Appendix E City of Renton Documents Vantage Point Apartments Technical Information Report Appendix E Site Improvement Bond Quantity Worksheet Original bond computations prepared by: Name: CHRISTOPHER BORZIO Dalee 1/27/2014 PE Registration Number: WA48787 Tel.#, (206) 926-0418 Firm Name: KPFF CONSUL TING ENGINEERS Address: 1601 FIFTH AVE STE 1600 SEATILE WA 98101 Project No: ___________ _ ROAD IMPROVEMENTS & DRAINAGE FACILITIES FINANCIAL GUARANTEE REQUIREMENTS PERFORMANCE BOND·, .. AMOUNT PUBLIC ROAD & DRAINAGE MAINTENANCE/DEFECT BONO",*" Stabilization/Erosion Sediment Control (ESC) (A) $ 15,896.7 Existing Right·of-Way Improvements (8) $ 68,885.8 Future Public Road Improvements & Drainage Facilities (C) $ Private Improvements (0) $ 579,575.9 Construction Bond'" Amount (A+B+C+D) TOTAL (T) $ 664,358.4 Minimum bond· amount is $1000. (B+C)x Maintenance/Defect Bond* Total 0.20 ~ $ 13,777.2 NAME OF PERSON PREPARING BOND~ REDUCTION: * NOTE: The word "bond" as used in this document means any financial guarantee acceptable to the City of Renton. 0 NOTE: All prices include labor, equipment, materials, overhead and profit. Prices are from RS Means data adjusted for the Seattle area or from local sources if not included in the RS Means database. REQUIRED BOND~ AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY RDSD Page 1 of 7 REF 8-H BOND QUANTITY WORKSHEET.xis Date: Unit prices updated: 2/12/02 Version: 4/22/02 Report Date: 1/31/2014 Site Improvement Bond Quantity Worksheet $ 5.62 CY 0.00 0.00 lGl-2 $ 8.53 CY 69 588.57 0.00 1201 GI -3 $ 0.36 SY 0.00 0.00 GI -4 $ 8,876.16 Acre 0.3 2,662.85 0.00 2.7 Excavation -bulk GI -5 $ 1.50 CY 0.00 0.00 20052 Excavation -Trench GI -6 $ 4.06 CY 69 280.14 0.00 1201 Fencing, cedar, 6' high GI -7 $ 18.55 LF 0.00 0.00 Fencing, chain link, vinyl coated, 6' high Gl-8 $ 13.44 LF 0.00 0.00 572 Fencing, chain link, gate, vinyl coated, 2 GI -9 $ 1,271.81 Each 0.00 0.00 4 Fencing, split rail, 3' high Gl-11 $ 12.12 LF 0.00 0.00 162 Fill & compact -common barrow Gl-1 1 $ 22.57 CY 0.00 0.00 1086 Fill & compact -gravel base GI -1 $ 25.48 CY 0.00 0.00 Fill & compact -screened topsoil Gl-1 $ 37.85 CY 0.00 0.00 Gabion, 12" deep, stone filled mesh Gl-1 $ 54.31 SY 0.00 0.00 Gabion, 18" deep, stone filled mesh Gl-1 $ 74.85 SY 0.00 0.00 IGabion, 36" deep, stone filled mesh Gl-1 $ 132.48 SY 0.00 0.00 1Grading, fine, by hand Gl-1 $ 2.02 SY 0.00 0.00 1460 Grading, fine, with grader GI -1 $ 0.95 SY 0.00 0.00 13149 Monuments, 3' long Gl-1 $ 135.13 Each 0.00 0.00 Sensitive Areas Sign Gl-2 $ 2.88 Each 0.00 0.00 Sodding, 1" deep, sloped ground Gl-21 $ 7.46 SY 0.00 0.00 Surveying, line & grade Gl-2 $ 788.26 Day 1 788.26 0.00 30 Surveying, lot location/lines Gl-2 $ 1,556.64 Acre 0.00 0.00 3 Traffic control crew ( 2 f1aggers ) Gl-2 $ 85.18 HA 120 10,221.60 0.00 Trail, 4" chipped wood Gl-2 $ 7.59 SY 0.00 0.00 Trail, 4" crushed cinder GI -2 $ 8.33 SY 0.00 0.00 Trail. 4" top course Gl-2 $ 8.19 SY 0.00 0.00 Wall, retaining, concrete Gl-2 $ 44.16 SF 0.00 0.00 111, rockery ~--2 • s . SC 0.00 0.00 Page 2 of 7 SUBTOTAL 14,541.42 0.00 REF 8-H BOND QUANTITY WORKSHEET.xis 10,244.53 0.00 23,965.63 30,078.00 4,876.06 0.00 7,687.68 5,087.24 1,963.44 24,511.02 0.00 0.00 0.00 0.00 0.00 2,949.20 12,491.55 0.00 0.00 0.00 23,647.80 4,669.92 0.00 0.00 0.00 0.00 0.00 u.00 152,172.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Uni1 prices updated: 2/12/02 Version: 4/22/02 Report Date: 1/31/2014 Site Improvement Bond Quantity Worksheet AC Grinding, 4' wide machine< 1000sy Rl-1 $ 23.00 SY 0.00 0.00 AC Grinding, 4' wide machine 1000-2000 RI -2 $ 5.75 SY 0.00 0.00 AC Grinding, 4' wide machine> 2000sy Rl-3 $ 1.38 SY 0.00 0.00 AC Removal/Disposal/Repair RI -4 $ 41.14 SY 137 5,636.18 0.00 Barricade, type I RI -5 $ 30.03 LF 0.00 0.00 Barricade, type Ill (Permanent) RI -6 $ 45.05 LF 0.00 0.00 Curb & Gutter, rolled Rl-7 $ 13.27 LF 0.00 0.00 Curb & Gutter, vertical RI -8 $ 9.69 LF 140 1,356.60 0.00 1410 Curb and Gutter, demolition and disposal Rl-9 $ 13.58 LF 140 1,901.20 0.00 Curb, extruded asphalt RI -1 $ 2.44 LF 0.00 0.00 Curb, extruded concrete Rl-11 $ 2.56 LF 0.00 0.00 Sawcut, asphalt, 3" depth Rl-1 $ 1.85 LF 395 730.75 0.00 Sawcut, concrele, per 1" depth Rl-1 $ 1.69 LF 0.00 0.00 Sealant, asphalt Rl-1 $ 0.99 LF 0.00 0.00 Shoulder, AC, ( see AC road unit price ) Rl-1 $ SY 0.00 0.00 Shoulder, gravel, 4" thick Rl-1 $ 7.53 SY 0.00 0.00 Sidewalk, 4" thick RI -1 $ 30.52 SY 587 17,915.24 0.00 2056 Sidewalk, 4" thick, demolition and dispos Al-1 $ 27.73 SY 0.00 0.00 Sidewalk, 5" thick Rl-1 $ 34.94 SY 0.00 0.00 Sidewalk, 5" thick, demolition and dispos RI -2 $ 34.65 SY 0.00 0.00 Sign, handicap Al -21 $ 85.28 Each 0.00 0.00 Striping, per stall RI -2 $ 5.82 Each 0.00 0.00 27 Striping, thermoplastic, ( for crosswalk) Al -2, $ 2.38 SF 0.00 0.00 :tnp1ng, 4ti re,1ectonzea 11ne IMI • 2.1 ~ 0.25 Le 0.00 O.m Page 3 of 7 SUBTOTAL 27,539.97 0.00 REF 8-H BOND QUANTITY WORKSHEET.xis 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13,662.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 62,749.12 0.00 0.00 0.00 0.00 157.14 0.00 0.uc 76,569.16 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 o.o, 0.00 Unit prices updated: 2/12/02 Version: 4/22/02 Report Date: 1/3112014 Site Improvement Bond Quantity Worksheet For KCRS '93, (additiorlal 2.5" base) add RS-1 $ 3.60 SY 0.00 0.00 AC Overlay, 1.5" AC RS -2 $ 7.39 SY 0.00 0.00 AC Overlay, 2" AC RS -3 $ 8.75 SY 0.00 0.00 AC Road, 2", 4" rock, First 2500 SY RS-4 $ 17.24 SY 0.00 0.00 AC Road, 2", 4" rock, Qty. over 2500SY RS-5 $ 13.36 SY 0.00 0.00 AC Road, 3", 4" rock, First 2500 SY RS-6 $ 19.69 SY 137 2,697.53 0.00 2500 AC Road, 3", 4" rock, Qty. over 2500 SY RS-7 $ 15.81 SY 0.00 0.00 303 AC Road, 5", First 2500 SY RS-8 $ 14.57 SY 0.00 0.00 :Ac Road, 5", Qty. Over 2500 SY RS -9 $ 13.94 SY 0.00 0.00 AC Road, 6", First 2500 SY S · 1 $ 16.76 SY 0.00 0.00 AC Road, 6", Qty. Over 2500 SY as -1 $ 16.12 SY 0.00 0.00 Asphalt Treated Base, 4" thick as -1 $ 9.21 SY 0.00 0.00 Gravel Road, 4" rock, First 2500 SY "15 -1 $ 11.41 SY 0.00 0.00 Gravel Road, 4" rock, Qty. over 2500 SY as -1 $ 7.53 SY 0.00 0.00 PCC Road, 5", no base, over 2500 SY as -1 $ 21.51 SY 0.00 0.00 $ 21.87 SY 0.00 0.00 • 6.o, LS O.u, "·"' Page 4 of 7 SUBTOTAL 2,697.53 0.00 REF 8-H BOND QUANTITY WORKSHEET.xis 0.00 0.00 0.00 0.00 49,225.00 4,790.43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 U.u, 54,015.43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 U.uu 0.00 Unit prices updated: 2/12/02 Version: 4/22/02 Report Date: 1/31/2014 Site Improvement Bond Quantity Worksheet :r:-.-:1,~'t:"":'\ ".,. . - Access Road. R/0 0-1 $ 16.74 SY 0.001 I 0.001 I Bollards -fixed 0-2 $ 240.74 Each 0.001 I 0.001 I Bollards -removable 0 · 3 $ 452.34 I Each I 0.001 I 0.001 I .. (CBs include frame and lid) CB Type I 0-4 $ 1,257.64 Each 0.00 0.00 17 CB Type IL 0-5 $ 1,433.59 Each 0.00 0.00 CB Type II, 48" diameter 0-6 $ 2,033.57 Each 2 4,067.14 0.00 2 for additional depth over 4' 0-7 $ 436.52 FT 6 2,619.12 0.00 2 CB Type II, 54" diameter 0-8 $ 2,192.54 Each 0.00 0.00 lor additional depth over 4' 0-9 $ 486.53 FT 0.00 0.00 CB Type II, 60" diameter 0-10 $ 2,351.52 Each 0.00 0.00 for additional depth over 4' 0-11 $ 536.54 FT 0.00 0.00 CB Type II, 72~ diameter 0-12 $ 3,212.64 Each 0.00 0.00 for additional depth over 4' 0-13 $ 692.21 FT 0.00 0.00 Through-curb Inlet Framework {Add) 0-14 $ 366.09 Each 0.00 0.00 Cteanout, PVC, 4" 0-15 $ 130.55 Each 0.00 0.00 Cleanout, PVC, 6" 0-16 $ 174.90 Each 0.00 0.00 9 Cleanout, PVC, 8" D -17 $ 224.19 Each 0.00 0.00 16 Culvert, PVC, 4" 0 -18 $ 8.64 LF 0.00 0.00 Culvert, PVC, 6" 0 -19 $ 12.60 LF 0.00 0.00 353 Culvert, PVC, 8" 0 -20 $ 13.33 LF 0.00 0.00 1390 Culvert, PVC, 12" 0 -21 $ 21.77 LF 70 1,523.90 0.00 739 Culvert, CMP, 8" 0 -22 $ 17.25 LF 0.00 0.00 Culvert, CMP, 12" 0 -23 $ 26.45 LF 0.00 0.00 Culvert, CMP, 15" 0 ~ 24 $ 32.73 LF 0.00 0.00 Culvert, CMP, 1a~ 0-25 $ 37.74 LF 0.00 0.00 Culvert, CMP, 24" 0-26 $ 53.33 LF 0.00 0.00 Culvert, CMP, 30" 0-27 $ 71.45 LF 0.00 0.00 D-28 $ 112.11 LF 0.00 0.00 0-29 $ 140.83 LF 0.00 0.00 $ 235.45 LF 0.00 0.00 • OU<.= c, U.uv U.u, Page 5 of 7 SUBTOTAL 8,210.16 0.00 REF 8-H BOND QUANTITY WORKSHEET.xis 0.001 0.001 O.OOJ. 21,379.88 0.00 4,067.14 873.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1,574.10 3,587.04 0.00 4,447.80 18,528.70 16,088.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 U.u, 70,545.73 "Ocllt -. ::-. 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 U.uv 0.00 Unit prices updated: 2/12/02 Version: 4/22/02 Report Date: 1/31/2014 Site Improvement Bond Quantity Worksheet $ Culvert, Concrete, 15" -D-34 $ 37.34 LF 0 0 Culvert, Concrete, 18" D-35 $ 44.51 LF 0 0 Culvert, Concrete, 24" D -36 $ 61.07 LF 0 0 Culvert, Concrete, 30" D -37 $ 104.18 LF 0 0 Culvert, Concrele, 36" D -38 $ 137.63 LF 0 0 Culvert, Concrele, 42" D -39 $ 158.42 LF 0 0 Culvert, Concrete, 48" D -40 $ 175.94 LF 0 0 Culvert, CPP, 6" D-41 $ 10.70 LF 0 0 Culvert, CPP. 8" D-42 $ 16.10 LF 0 0 Culvert, CPP, 12" D -43 $ 20.70 LF 0 0 Culvert, CPP, 15" D-44 $ 23.00 LF 0 0 Culvert, CPP, 18" D -45 $ 27.60 LF 0 0 Culvert, CPP, 24" D -46 $ 36.80 LF 0 0 Culvert, CPP, 30'' D -47 $ 48.30 LF 0 0 Culvert, CPP, 36" D -48 $ 55.20 LF 0 0 Ditching D -49 $ 8.08 CY 0 0 Flow Dispersal Trench (1,436 base+} D -50 $ 25.99 LF French Drain (3' depth) D-51 $ 22.60 LF 0 0 Geotextile, laid in trench, polypropylene D -52 $ 2.40 SY 0 0 Infiltration pond testing D -53 $ 74.75 HR 0 0 Mid-tank Access Riser, 48" dia, 6' deep D -54 $ 1,605.40 Each 0 0 Pond Overflow Spillway D -55 $ 14.01 SY 0 0 Reslrictor/Oil Separator, 12" D -56 $ 1,045.19 Each 0 0 1 Aestrictor/Oil Separator, 15" D -57 $ 1,095.56 Each 0 0 Restrictor/Oil Separator. 18" D -58 $ 1,146.16 Each 0 0 Riprap, placed D-59 $ 39.08 CY 0 0 Tank End Reducer (36" diameter) D -60 $ 1,000.50 Each 0 0 Trash Rack, 12" 0-61 $ 211.97 Each 0 0 Trash Rack, 15" D -62 $ 237.27 Each 0 0 $ 268.89 Each 0 0 """! .,,,. t:.acn . I Page Sol 7 SUBTOTAL 0 0 REF 8-H BOND QUANTITY WORKSHEET.xis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1045.19 0 0 0 0 0 0 0 ' 1045.19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I 0 Unit prices updated: 2/12/02 Version: 4/22/02 Report Da1e: 1/31/2014 Site Improvement Bond Quantity Worksheet No. 2" AC, 2" top course rock & 4" borrow PL-1 $ 15.84 SY 0 1) ------ 0 2" AC, 1.5" top course & 2.5" base cour PL-2 $ 17.24 SY 0 0 0 4" select borrow PL-3 $ 4.55 SY 0 0 0 1.5" top course rock & 2.5" base course PL-4 $ 11.41 SY 0 0 0 !i&M.bkffhlC:-'W·;;"'-~"·:i. :, .H~.:S-..,·~-,··1 _ ,,,.s}'"1~,_,..}· ' .. ,. -. .,--'l-·_':>.__,,_'-'it ~ .. ;1;:.· .. ,,, (Such as detention/water quality vaults.) I No. Wl-1 0 0.00 0.00 Wl-2 0 0.00 0.00 AREA DRAIN WI -3 $ 500.00 Each 0 0.00 13 6.500.00 TRENCH DRAIN Wl-4 $ 5,000.00 Each 0 0.00 4 20,000.00 GRASSCRETE Wl-5 $ 50.00 SY 0 0.00 839 41.950.00 PERVIOUS PAVEMENT Wl-6 $ 35.00 SY 0 0.00 658 23,030.00 Wl-7 0 0.00 0.00 Wl-8 0 0.00 0.00 Wl-9 0 0.00 0.00 Wl-10 0 0.00 U.uc SUBTOTAL 0.00 0.00 91,480.00 SUBTOTAL (SUM ALL PAGES): 52,989.08 0.00 445,827.58 30% CONTINGENCY & MOBILIZATION: 15,896.72 0.00 133,748.27 GRANDTOTAL: 68.885.80 0.00 579,575.86 COLUMN: B C D Page 7 of 7 REF 8-H BOND QUANTITY WORKSHEET.xis _ lllidllClloll" ~ 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 U.uu 0.00 0.00 0.00 0.00 E Unit prices updated: 2/"12/02 Version: 4/22/02 Report Date: 1/31/2014 RECORDING REQUESTED BY AND WHEN RECORDED MAIL TO: CITY CLERK'S OFFICE CITY OR RENTON 1055 SOUTH GRADY WAY RENTON. WA 98057 DECLARATION OF COVENANT FOR INSPECTION AND MAINTENANCE OF STORMWATER FACILITIES AND BMPS Grantor: _____________ _ Grantee: City or Renton Legal Description: __ _ Additional Lcgal(s) on: Assessor's Tax Parcel ID#: _____________ _ ------------- IN CONSIDERATION of the approved City or Renton permit for application file No. LUA/SWP relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covcnants(covenant) with the City or Renton, a political subdivision of the state of Washington, that he/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 10 below with regard to the Property, and hereby grants(grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agree) as follows: L The Grantor(s) or hislher(their) successors in interest and assigns ("Owners") shall at their own cost, operate, maintain, and keep in good repair, the Property's stormwater facilities and best management practices ("BMPs") identified in the plans and specifications submitted to King County for the review and approval of pennit(s) #: ------------~ Stonnwater facilities include pipes, swales, tanks, vaults, ponds, and other engineered structures designed to manage stormwater on the Property. Stormwater BMPs include dispersion and infiltration devices, native vegetated areas, penneable pavements, vegetated roofs, rainwater harvesting systems, reduced impervious surface coverage, and other measures designed to reduce the amount of stonnwater runoff on the Property. 2. City or Renton shall have the right to ingress and egress over those portions of the Property necessa1y to perform inspections of the storm water facilities and BMPs and conduct other activities specified in this Declaration of Covenant and in accordance with RMS 4-6-030. This right of ingress and egress, right to inspect, and right to perforrn required maintenance or repair as provided for in Section 3 below, stall not extend over those portions of the Property shown in Exhibit "A." 3. lf City of Renton detennines that maintenance or repair work is required to be done to any of the stormwater facilities or BMPs, City of Renton shall give notice of the specific maintenance and/or repair work required pursuant to RMC 4-6-030. The City shall also set a reasonable time in which such work is to be completed by the Owners. If the above required maintenance or repair is not completed within the time set by the City, the City may perform the required maintenance or repair, and hereby is given access to the Property, subject to the exclusion in Paragraph 2 above, for such purposes. Written notice will be sent to the Owners stating the City's intention to perform such work. This work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and maintenance and/or repair work will begin immediately. 4. If at any time the City of Renton reasonably detem1ines that a stonnwater fae1lity or BMP on the Property creates any of the hazardous conditions listed in KCC 9.04.130 or relevant municipal successor's codes as applicable and herein incorporated by reference. The City may take measures specified therein. 5. The Owners shall assume alJ responsibility for the cost of any maintenance or repair work completed by the City as described in Paragraph 3 or any measures taken by the County to address hazardous conditions as described in Paragraph 4. Such responsibility shall include reimbursement lo the County within thirty (30) days of the receipt of the invoice for any such work perfonned. Overdue payments will require payment of interest al the current legal rate as liquidated damages. If legal action ensues, the prevailing party is entitled to costs or fees. 6. The Owners are hereby required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stonnwater facilities (such as swalcs, channels, ditches, ponds, etc.), or perfonning any alterations or modifications to the storm\vatcr facilities and BMPs referenced in this Dec1aration of Covenant. 7. Any notice or consent requ!fed to be given or otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified 1\llail, return receipt requested. 8. With regard to the matters addressed herein, this agreement constitutes the entire agreement between the parties. and supersedes all prior discussions, negotiations, and all agreements whatsoever whether oral or written. 9. This Declaration of Covenant is intended lo protect the value and desirability of the real property described above, and shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest, and assigns. 3 10. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City that is recorded by King County in its real property records TN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Stormwater Facilities and BMPs is executed this day of ________ , 20 __ GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF W ASH!NGTON ) COlJNTY OF KING )ss. On this day personally appeared before me: -------------·--------·tome known to be the indiYidual(s) described in and who executed the withm and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this __ day of _________ , 20 __ Printed name Notary Public in and for the State of Washington, cesiding at My appointment expires RECORDING REQUESTED BY AND WHEN RECORDED MAIL TO: CITY CLERK'S OFFICE CITY OF RENTON 1055 SOUTH GRADY WAY RENTON WA 98057 DECLARATION OF COVENANT FOR MAINTENANCE AND INSPECTION OF FLOW CONTROL Bl\1PS Grantor: _____________ _ Grantee: City of Renton Legal Description: ___________________________ _ Additional Legal(s) on:-------------------------- Assessor's Tax Parcel ID#:------------------------- IN CONSIDERATION of the approved City of Renton( check one of the following) D residential building permit, D commercial building pcnnit, D clearing and grad mg permit, D subdivision pennit, or D short subdivision pennit for Application File No. LUAISWP ________ relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants( covenant) with City or Renton, a political subdivtsion of the state of Washington, that hc/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs I through 8 below with regard to the Property. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agrce) as follows: l. Grantor(s) or his/her(their) successors in interest and assigns ("Owners") shall retain, uphold, and protect the stormwater management devices, features, pathways, limits, and restrictions, known as /1ow control best management practices ("BMPs"), shown on the approved Flow Control BMP Site Plan for the Property attached hereto and incorporated herem as Exhibit A. 2. The Owners shall at their own cost, operate, maintain, and keep in good repair, the Property's BMPs as described in the approved Design and Maintenance Details for each BMP attached hereto and incorporated hercm as Exhibit B. 3. City or Renton shall provide at least 30 days written notice to the Owners that entry on the Property is planned for the inspection of the BMPs. After the 30 days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting the BV!Ps. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state ofWashmgton who has expertise m drainage to inspect the BMPs and provide a written report descnbmg their conditlOn. lf the engineer option 1s chosen, the Owners shall provide written notice to the City of Renton withm fifteen days of recc1vmg the City's notice of inspection. Withm 30 days of gtving this notice, the Owners, or the engineer on behalf of the Owners .. shall provide the engineer's report to the City of Renton. If the report is not provided in a timely mannei as specified above, the County may mspcct the BMPs without further notice. 4. If the City determines from its inspection, or from an engineer's report provided in accordance with Paragraph 3, that maintenance, repair, restoration, and/or mitigatwn work is required for the BMPs. The City shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work) required under RMC 4-6-030. The City shall also set a reasonable deadline for completing the Work or providing an engineer's report that verifies completion of the Work. After the deadline has passed. the Owners shall allow the City access to re-inspect the BMPs unless an engineer's report has been provided verifying completion of the Work. If the work is not completed properly within the time frame set by the City, the City may initiate an enforcement action. Failure to properly maintain the BMPs rs a v10lation ofRMC 4-6-030 and may subject the Owners to enforcement under the RMC 1-3, including fines and penalties. 5. Apart from perfonning routine landscape maintenance, the Owners arc hereby required to obtain written approval from the City or Renton before perfonning any alterations or modifications to the BMPs. 6. Any notice or approval required to be given by one party to the other under the provisions of this Declaration of Covenant shall be effective upon personal delivery to the other party, or after three (3) days from the date that the notice or approval is mailed with delivery eonfinnation to the current address on record with each Party. The parties shall notify each other of any change to their addresses. 7. This Declaration of Covenant is intended to promote the efficient and effective management of surface water drainage on the Property, and it shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors m interest and assigns. 8. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City of Renton that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Maintenance and Inspection of Flow Control BMPs is executed this __ day of _________ , 20 __ GRANTOR, owner of the Property GRANTOR, owner of the Property ST A TE OF W ASHlNGTON COUNTY OF KING )ss. On this day personally appeared before me: ___________________ ,to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this__ day of _______ ,20 Printed name Notary Public in and for the State of Washington, residing at My appointment expires _________ _ RECORDING REQUESTED BY AND WHEN RECORDED MAIL TO: CITY CLERK'S OFFJCE CITY OF RENTON l 055 SOUTH GRADY WAY RENTON, WA 98057 DECLARATION OF COVENANT FOR IMPERVIOUS SURFACE LIMIT Granter: __ _ Grantee: City of Renton Legal Descnption: ________________________ _ Additional Legal(s) on: ________ _ Assessor's Tax Parcel ID#: __________ _ IN CONSIDERATION of the approved City of Renton ____ _ _ ____ permit for application file No. LUA/SWP ________ relating to real property legally described above, the undersigned as Grantor(s), declares(dcclare) that the above described property is hereby established as having a limit to the amount of impervious surface allowed on the property for the purpose of limiting stonnwater flO\VS and is subject to the following restrictions. The Grantor(s) hereby covenants(covenant) and agrees(agree) as follows: no more than ____ square feet of impervious surface coverage is allowed on the property. Impervious surface means a hard surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions before development; or that causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Co1mnon impervious surfaces include, but are not limited to, roof, walkways, patios, driveways, parking lots, or storage areas, areas that are paved, graveled or made of packed or oiled earthen materials, or other surfaces that similarly impede the natural infiltration of surface and stonn water. Clty of Renton or its mumcipal successors shall have a nonexclusive perpetual access easement on the Properly in order to mgress and egress over the Property for the sole purposes of inspecting and monitoring the Property's impervious surface coverage. This casement/restriction is binding upon the Grantor(s), its heirs, successors, and assigns unless or until a new drainage or site plan is reviewed and approved by the Renton Development Services Division or its successor. IN WIT'\'ESS WHEREOF, this Declaration of Covenant is executed this __ day of ,20 GRA\!TOR, owner of the Property GRANTOR, owner of the Property ST ATE OF WASHINGTON COUNTY OF KING )ss. On this day personally appeared before me: --------, to me known to be the indiv1dual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this __ day of _________ , 20 __ Printed name Notary Public in and for the State of Washington, residing at My appointment expires---------~ RECORDING REQUESTED BY A;',;D WHEN RECORDED MAIL TO CITY CLERK'S OFFICE CITY OF RENTON 1055 SOUTJI GRADY WAY RENTON WA 98057 DECLARATION OF COVENANT FOR CLEARING LIMIT Gran tor Grantee: City of Renton Legal Description: ____ .---------------- Additional Lcgal(s) on: ----------------- Assessor's Tax Parcel ID#: IN CONSIDERATION of the appro,·ed City of Renton _____ _ ------ for applicat>on file No. LUA/SWP __________ relating to the real property permit ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby declares (declare) that the Property is established as having a nati\'e growth retention area for the purpose of dispersing and treating stonnwater flows and is subject to restrictions applying to vegetation removal in all designated areas shown in Exhibit A attached hereto, and hereby covenants ( covenant) and agrees (agree) as follows: 1. Any alterations to critical areas, their buffers, and native growth retention areas shall be pursuant to applicable Renton Municipal Code. 2. The property within the native growth protection area (shown in Attachment A) shall be maintained in a forested condition, with the exception of open water and existing non-forested native wetland plant conununities. The following activities are allowed and must be done in a manner that maintains forested hydrologic conditions and soil stability: a. Removal of noxious weeds and non-native vegetation using hand equipment, provided that those areas are replanted with appropriate native vegetation. b. Removal of dangerous and diseased trees. c. Passive recreation and related activities including trails, nature viewing, fishing, camping areas, and other similar activities that do not require permanent structures, provided that cleared areas and areas of compacted soil associated with these areas and facilities do not exceed eight percent of the native growth retention area. d. The native growth retention area may contain utilities and utility easements including flow control BMPs, but not including septic systems. e. Limited trimming and pruning of vegetation for the creation and maintenance of views per applicable Renton Municipal Code. f. T1mbe1 harvest in accordance with the City of Renton Tree Clearing and Land Regulations, the Department of Natural Resources forest practices pennit, and if applicable, the City of Renton Urban Separator Overlay Regulations. 3. City of Renton shall ha\'c a nonexclusive perperual access casement on the Property in order to ingress and egress over the Property for the sole purposes of inspecting and monitoring the Property's native growth retention area. 4. This easement/restriction 1s binding upon the Grantor(s), his/her (their) heirs, successors and assigns unless or until a new drainage or site plan is reviewed and approved by the the Cny of Renton or its successor. IN WITNESS WHEREOF, this Declaration of Covenant is executed this __ day of ___ , 20 STATE OF WASIILNGTON COUNTY OF KING )ss. On this day personally appeared before me: GRANTOR, owner of the Property GRANTOR, owner of the Property ______________ ,to me known to be the individual(,) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this ___ day of ______ ,20 __ Printed name Notary Public in and for the State of Washington, residing at My appointment expires __________ _ Appendix F Operations and Maintenance Manual Vantage Point Apartments Technical Information Report Appendix F APPEKDIX A MA!NTE;JANCE RFQUIRFMENTS FLOW CONTROL COKVEY ANCE, AND WQ FACILITIES -----------~l NO. 1 -DETENTION PONDS M -1: I P ble Cond'tion Wh n Ma· tenance I Needed Result Expected When am enance e ec or ro m I s e m s s Component Maintenance Is Performed ' ' '~ Sile l "'" '""""' Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet (this is about equal to the I amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. I i Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious I vegetation where County personnel or the public might normally be. Contaminants arid Any evidence of contaminants or pollution such I Materials removed and disposed of I pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. ' I Source control BMPs implemented If appropriate No contaminants ' ' ,_,, ~--. ,, ..... j Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height height no greater than 6 inches Top or Side Slopes Rodent holes Any evidence of rodent holes if facility is acting ,-~·-'"'·-·"" I of Dam, Berm or as a dam or berm, or any evidence of water dam or berm repaired Embankment piping through dam or berm via rodent holes. ---- Tree growth Tree growth threatens integrity of slopes, does Trees do not hinder fac11tty not allow maintenance access, or interferes with performance or maintenance ' maintenance activity. If trees are not a threat or act1v1t1es not interfering wllh access or maintenance, they do not need to be removed. ' Erosion Eroded damage over 2 inches deep where cause Slopes stabilized using appropriate of damage is still present or where there is erosion control measures. II erosion potential for continued erosion. Any erosion is occurring on compacted slope, a observed on a compacted slope. licensed civil engineer should be consulted to resolve source of erosion. --~,--, Settlement Any part of a dam, berm or embankment that has Top or side slope restored to design ! I settled 4 inches luwer than the design elevation. dimensions. If settlement is significant, a licensed civil engineer I should be consulted to determine I the cause of the settlement. Storage Area 1 Sediment Accumulated sediment that exceeds 10% of the Sediment cleaned out to designed accumulation designed pond depth. pond shape and depth; pond reseeded if necessary to control erosion _, ' ~--, Liner damaged Liner is visible or pond does not hold water as Liner repaired or replaced. (If Applicable) designed. ----· ~' Inlet/Outlet Pipe. Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. ' accumulation ~ Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes (includes floatab!es and non-floatables) Damaged Cracks wider than %-inch at the joint of the No cracks more than '/..-inch wide at inlet/outlet pipes or any evidence of soi! entering the joint of the inlet/outlet pipe. at the joints of the inleUoutlet pipes. I Eme,gency Tree growth Tree growth impedes flow or threatens stability of Trees removed. Overflow/Spillway ' spillway. l Rock missing Only one layer of rock exists above native soil in Spillway restored to design I area five square feet or larger or any exposure of standards. native soil on the spillway. 1/9,2009 2009 Surface Water Design Manual -Appendix A A-2 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, Al\D WQ FACILITIES NO. 4 -CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Trash and debris Trash or debris of more than ~ cubic foot which No Trash or debris blocking or is located immediately in front of the structure potentially blocking entrance to opening or is blocking capacity of the structure by structure. more than 10%. Trash or debris in the structure that exceeds 1/3 No trash or debris in the structure. the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Deposits of garbage exceeding 1 cubic foot in No condition present which would volume, attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60% of the depth from the Sump of structure contains no bottom of the structure to the Invert of the lowest sediment. pipe into or out of the structure or the bottom or the FROP-T section or is within 6 inches of the invert or the lowest pipe into or out of the structure or the bottom or the FROP-T section. Damage to frame Corner of frame extends more than :Y. inch past Frame is even with curb. and/or top slab curb face into the street (If applicable}. Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than 'X inch. Frame not sitting flush on top stab, i.e., Frame is sitting flush on tap slab. separation of more than l~ inch of the frame from the top slab. Cracks in waifs or Craeks wider than Y.i inch and longer than 3 feet, Structure is sealed and structurally bottom any evidence of soil particles entering structure sound. through cracks, or maintenance person judges that structure is unsound. Cracks wider than X inch and longer than 1 foot No cracks more than 1 /4 inch wide at at the joint of any inleVouilet pipe or any evidence the joint of inleUoutlet pipe of soil particles entering structure through cracks. Settlement{ StnJcture has settled rnore than 1 inch or has Basin replaced or repaired to design misalignment I rotated more than 2 inches out of alignment standards . .. ~ Damaged pipe joints Cracks wider than Y.i-inch at the joint of the No cracks more than 1/.i-inch wide at inlet/outlet pipes or any evidence of sotl entering the joint of inlet/outlet pipes. the structure at the joint of the inlet'outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder 11.Jngs missing Ladder is unsafe due to missing rungs, Ladder meets design standards and or unsafe misalignment, rust, cracks, or sharp edges. allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure T section securely attached to wall wall and outlet pipe structure should support at and outlet pipe. least 1,000 lbs of up or down pressure. Structure is not in upright position (allow up to Structure in correct position. 10% from plumb}. Connections to outlet pipe are not watertight or Connections to outlet pipe are water show signs of deteriorated grout. tight; structure repaired or replaced and works as designed. Any holes-other than designed hates-in the Stn.icture has no holes other than structure. designed holes. Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. 2009 Surface Water Design Manual -Appendix A 1/9/2009 A-7 APPENDIX A MAINTEJ\A'<CE REQLIREME'<TS FLOW CONTROi., CONVEYAJ\CE, AND WQ FACILITIES --------·----------·---- I NO, 4 -CONTROL STRUCTURE/FLOW RESTRICTOR ---~--- Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed ,_____ -- I Cleanout gate is not watertight. i Gate is watertight and works as I designed. ~- ! -- Gate cannot be moved up and down by one Gate moves up and down easily and maintenance person. i 1s watertight Chain/rod leading to gate is missing or damaged. I Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to ! Plate is in place and works as I missing, out of place, or bent orifice plate. 1 designed. --·rP1a1e is tree at a11 obstructions and Obstructions Any trash, debris, sediment, or vegetation blocking the plate. ' works as designed Overflow Pipe ' Obstructions Any trash or debris blocking {or having the Pipe is free of all obstructions and potential of blocking} the overflow pipe. works as designed. ------- Deformed or damaged Lip of overflow pipe is bent or deformed. Overflow pipe does not allow lip overtlow at an elevation lower than design Inlet/Outlet Pipe Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation -- Trash and debris Trash and debris accumulated in inlet/outlet I No trash or debris in pipes pipes {includes floatables and non-floatables). ' Damaged Cracks wider than 'h-inch al the joint of the No cracks more than %-inch wide al inlet/outlet pipes or any evidence of soil entering the Joint of the inlet/outlet pipe at the joints of the inletloutlet pipes. ----- Metal Grates Unsafe grate opening Grate w,th opening wider than 7 /6 inch Grate opening meets design (If Applicable) standards. L:sh and debris Trash and debris that is blocking more than 20% Grate free of trash and debris of grate surtace. footnote to guidelines for d1sposa! Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design I I standards Mar.role Cover/lid ! Cover/lid not in place Cover/lid is missing or only partially in place Cover/lid protects openi!lg to Any open structure requires urgent structure maintenance. ---- Lockir,g mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. ------·--- i Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs. of Ii~. reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual -Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance Is Performed Structure Sediment Sediment exceeds 60% of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of morEI than "Ai cubic foot which No Trash or debris blocking or is. located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capacity of the catch basin catch basin. by more than 10%. Trash or debris in the catch basin that exceeds No trash or debris in the catch basin. 1 /3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within catch basin. gases (e.g., methane), Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Damage to frame Corner of frame extends more than % inch past Frame is even with curb. and/or top slab curb face into the street (If applicable). Top slab has holes larger than 2 square Inches or Top slab is free of holes and cracks. cracks wider than 1..4 inch. Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than o/., inch of the frame from the .top slab. Cracks in walls or Cracks wider than 'h inch and longer than 3 feet, Catch basin is sealed and bottom any evidence of soil particles entering catch structurally sound. basin through cracks, or maintenance person judges that catch basin is unsound. Cracks wider than }S inch and longer than 1 foot No cracks more than 1 /,. inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe. of soil particles entering catch basin through cracks. Settlement/ Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment standards. Damaged pipe joints Cracks wider than 'h-inch at the joint of the No cracks more than '/.-inch wide at inletloutlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the catch basin at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pol!ution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface ail film. Inlet/Outlet Pipe Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes pipes (includes floatables and non-floatables). Damaged Cracks wider than Yz-inch at the joint of the No cracks more than 1/.i-inch wide at inleVoutlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 2009 Surface Water Design Manual -Appendix A 119/2009 A-9 APPENDIX A MAINTEN.~NCE REQCIREYIENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES ,-------~---··--·--------------J NO. 5 -CATCH BASINS AND MANHOLES e--------------------r ' Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When I Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than 'le inch. i Grate opening meets design (Catch Basins) I standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal -~ Damaged or missing Grate missing or broken member(s) of the grate. Grate 1s in place and meets design Any open structure requires urgent standards. maintenance. - Manhole Cover/Lid Cover/lid not in place ! Cover/lid is missing or only partially in p!ace Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools. Bolts I cannot be seated. Self-lockin.g cover/lid does not work. Cover/lid d1ff1cuit to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs. of lift. reinstalled by one maintenance I person. 1'9,2009 2009 Surface Water Design Manual~ Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 -CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment & debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20% of the diameter of the pipe. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged; rust or corrosion Pipe repaired or replaced coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20'% or is determined to have weakened structural integrity of the pipe. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches Sediment Accumulated sediment that exceeds 20% of the Ditch cleaned/flushed of all sediment accumulation design depth. and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the pub1ic might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. , Source control BMPs implemented if appropriate. No contaminants present other lhan a surface oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion absented on a ditch slope. Slopes are not eroding. slopes Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. place or missing (If area 5 square feet or more, any exposed native Applicable) soil. 2009 Surface Water Design Manual -Appendix A 119/2009 A-11 Al'FEN:JJX A M,\INTJ )-IA"CE RE()LJREMcNTS FLOW CO"TROL, CONVEYANCE, AND WQ r ACILITIES -----·----------~ NO. 7 -DEBRIS BARRIERS (E.G., TRASH RACKS) --------· ---- Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed. Site Trash and debris Trash or debris plugging more than 20% of the Barrier clear to receive capacity flow. ' area of the barrier. I -. ! Sediment Sediment accumulat,on of greater them 20% of Barrier clear to receive capacity flow. I accumulation the area of the barrier Structure Cracked broken or Structure which bars attached to is damaged -Structure barrier attached to is i loose pipe is loose or cracked or concrete structure is sound. I cracked, broken of loose. 1 Bars Bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inche spacing. : Damaged or missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more ! bars than Y.. inch ' Bars are missing or entire barrier missing ' Bars in place according to design. Bars are loose and rust is causing 50% Repair or replace barrier to design I : deterioration to any part of barrier. ' standards. ------------·------ J/9/2009 2009 Surface Water Design Manual -Appendix A A-12 APPENDTX A MAINTENANCE REQUIREY!ENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 9 -FENCING Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Erosion or holes Erosion or holes more than 4 inches high and 12-No access under the fence. under fence 18 inches wide permitting access through an opening under a fence. Wood Posts, Boards Missing or damaged Missing or broken boards, post out of plumb by No gaps on fence due to missing or and Cross Members parts more than 6 inches or cross members broken broken boards, post plumb to within 11/, inches, cross members sound. Weakened by rotting Any part showing structural deterioration due to All parts of fence are structurally or insects rotting or insect damage sound Damaged or failed Concrete or metal attachments deteriorated or Post foundation capable of post foundation unable to support posts. supporting posts even in strong wind. Metal Posts. Rails Damaged parts Post out of plumb more than 6 inches. Post plumb to within 1 Y:i inches. and Fabric Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part offence (including post, top rails, and Fence is aligned and meets design fabric) more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or Part or parts that have a rusting or scaling Structurally adequate posts or parts protective coating condition that has affected structural adequacy. with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch Fabric mesh openings within 50% of diameter ball could flt through. grid size 1/9,2009 2009 Surface Water Design Manual -Appendix A A-14 APPFI\DIX A MAINTENAcsCE REQUIREMENTS FOR FLOW CONTROL, CONVEY A'ICE, A'ID WQ FACILI rIES -----------------~-----·----------------- ---- Maintenance Defect or Problem I Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed r:NO. 10 -GA TES/BOLLARDS/ACCESS BARRIERS ~·hain Link Fencing - Damaged or missing Missing gate Gates in place. Gate members I Broken or missing hinges such that gate cannot Hinges intact and lubed Gate is be easily opened and closed by a maintenance working freely. person. -- Gate is out of plumb more than 6 inches and Gate is aligned and vertical. more than 1 foot out of design alignment. ---- Missing stretcher bar, stretcher bands, and ties. ' Stretcher bar. bands, and ties in ! place. ! Locking mechanism Locking device missing, no-functioning or does Locking mechanism prevents I does not lock gate not link to all parts. opening of gate I i Openings in fabric Openings in fabric are such that an 8-inch Fabric mesh openings within 50% of I diameter bal! could fit through grid size Bar Gate j Damaged or missing Cross bar does not swing open or closed, is Cross bar swings fully open and i cross bar missing or is bent to where it does not prevent closed and prevents vehicle access I vehicle access. Locking mechanism Locking device missing, no-functioning or does Lo~ki~~ ~echanism.prevents: does not lock gate not link to all parts. opening of gate ' I Support post does not hold cross bar up. -j Support post Cross bar held .up preventing vehicle I damaged access into facility. i ~· . --1 Bollards Damaged or missing Bollard broken, missing, does not fit into support No access for motonzed vehicles to I ho:e or hinge broken or missing. --.. ---~· -·· get into facility. Does not lock Locking assembly or lock missing or cannot be No access for motorized vehicles to i attached to lock bollard in place. get into facility. ! -- I Boulders Dislodged Boulders not located to prevent motorized vehicle No access for motorized vehicles to ! get into facility. ' access. Circumvented Motorized vehicles going around or between i No access for motorized vehicles to boulders. get into facility. ' ! 2009 Surface Water Design Manual -Appendix A I/9/2009 A-15 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES N0.11 -GROUNDS (LANDSCAPING) Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash or litter Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can}. In general. there should be no visual evidence of dumping. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might nonnaUy be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline. concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Trees and Shrubs Hazard Any tree or limb of a tree idenUfied as having a No hazard trees in facility. potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. Damaged Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of !he total Trees and shrubs with less than 5% of total foliage with split or broken foliage of the tree or shrub. limbs. Trees or shrubs that have been blown down or No blown down vegetation or knocked over. knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately Tree or shrub in place and supported or are leaning over, causing exposure adequately supported; dead ar of the roots. diseased trees removed. l/9,'2009 2009 Surface Water Design Manual -Appendix A A-16 APPE'IDIX A \1Al'ITENAKCE REQUIREMENTS FOR FLOW CONTROL, CONVcYANCE, AND WQ FACILITIES ----- NO. 12-ACCESS ROADS Maintenance Defect or Problem Condition When Maintenance is Needed I Results Expected When Component I Maintenance is Performed Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 ! Roadway drivable by maintenance square fee1 {i.e., trash and debris would fill up I vehicles. one standards size garbage can). Debris which could damage vehicle tires or Roadway drivable by maintenance prol'iibit use of road. vehicles. ! Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film Blocked roadway Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restricting the access to a 10-to At least 12-foot of width on access 12 foot width for a distance of more than 12 feet road or any point restricting access to less than a 10 foot width. - Road Surface Erosion, settlement, Any surface defect which hinders or preven:s Road drivable by maintenance potholes, soft spots. maintenance access. vehicles. ruts ---- I Vegetation on road Trees or other vegetation prevent access to Maintenance vehicles can access surface facility by maintenance vehicles. facility Shoulders and Erasion Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. ·----- Weeds and brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches in hinder maintenance access. height or cleared in such a way as to allow maintenance access. -- Modular Grid Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of Pavement pollution as oil, gasoline. concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. ----·--·--------·----------- Damaged or missing Access surface compacted because of broken on Access road surface restored so i missing modular block. road infiltrates 2009 Surface Water Design Manual -Appendix A 1/912009 A-17 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, A"ID WQ FACILITIES NO. 24 -CATCH BASIN INSERT Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Media Insert Visible Oil Visible oil sheen passing through media Media inset replaced Insert does not fit Flow gets into catch basin without going through All flow goes through media. catch basin properly media. Filter media plugged Filter media plugged Flow through filter media is normal. Oil absorbent media Media oil saturated. Oil absorbent media replaced. saturated Water saturated Catch basin insert is saturated with water, which Insert replaced. no longer has the capacity to absorb. --~--~ Service life exceeded Regular interval replacement due to typical Media replaced at manufacturer's average life of media insert product. typically one recommended interval. month. Seasonal When storms occur and during the wet season. Remove, clean and replace or install maintenance new insert after major storms, monthly during the wet season or at manufacturer's recommended interval. 2009 Surface Water Design Manual -Appendix A 1/9/2009 A-35 C.2.5 RAIN GARDEN C.2.5.3 MAINTENANCE INSTRUCTIONS FOR A RAIN GARDEN Jfthe rain garden flow control BMP is proposed for a project, the following maintenance and operation instructions must be recorded as an attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section C.1.3.3 (p. C-18). The intent of these instructions is to explain to future property owners, the purpose of the BMP and how it must be maintained and operated. These instructions are intended to be a minimum; DDES may require additional instructions based on site- specific conditions. Also, as the County gains more experience with the maintenance and operation of these BMPs, future updates to the instructions will be posted on King County's Surface Water Design Manual website. Cl TEXT OF INSTRUCTIONS Your property contains a stormwater management flow control BMP (best management practice) called a "rain garden," which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impervious or non-native pervious surfaces on your property. Rain gardens, also known as "bioretention," are vegetated closed depressions or ponds that retain and filter stormwater from an area of impervious surface or non-native pervious surface. The soil in the rain garden has been enhanced to encourage and support vigorous plant growth that serves to filter the water and sustain infiltration capacity. Depending on soil conditions, rain gardens may have water in them throughout the wet season and may overflow during major storm events. The size, placement, and design of the rain garden as depicted by the flow control BMP site plan and design details must be maintained and may not be changed without written approval either from the King County Water and Land Resources Division or through a future development permit from King County. Plant materials may be changed to suit tastes, but chemical fertilizers and pesticides must not be used. Mulch may be added and additional compost should be worked into the soil over time. Rain gardens must be inspected annually for physical defects. After major storm events, the system should be checked to see that the overflow system is working properly. If erosion channels or bare spots are evident, they should be stabilized with soil, plant material, mulch, or landscape rock. A supplemental watering program may be needed the first year to ensure the long-term survival of the rain garden's vegetation. Vegetation should be maintained as follows: 1) replace all dead vegetation as soon as possible; 2) remove fallen leaves and debris as needed; 3) remove all noxious vegetation when l, discovered; 4) manually weed without herbicides or pesticides; 5) during drought conditions, use mulch to prevent excess solar damage and water loss. 2009 Surface Water Design Manual -Appendix C 1/912009 C-63 C.2.6 PERMEABLE PAVEMENT some or all of the paved surfaces on your property. Permeable pavements reduce the amount of rainfall that becomes runoff by allowing water to seep through the pavement into a free-draining gravel or sand bed, where it can be infiltrated into the ground. The type(s) of permeable pavement used on your property is: D porous concrete. D porous asphaltic concrete, D permeable pavers, D modular grid pavement. The area covered by permeable pavement as depicted by the flow control BMP site plan and design details must be maintained as permeable pavement and may not be changed without written approval either from the King County Water and Land Resources Division or through a future development permit from King County. Permeable pavements must be inspected after one major storm each year to make sure it is working properly. Prolonged ponding or standing water on the pavement surface is a sign that the system is defective and may need to be replaced. If this occurs, contact the pavement installer or the King County Water and Land Resources Division for further instructions. A typical permeable pavement system has a life expectancy of approximately 25-years. To help extend the useful life of the system, the surface of the permeable pavement should be kept clean and free of leaves, debris, and sediment through regular sweeping or vacuum sweeping. The owner is responsible for the repair of all ruts, deformation, and/or broken paving units. Cl TEXT OF INSTRUCTIONS FOR VEGETATED PERMEABLE PAVEMENT Your property contains a stormwater management flow control BMP (best management practice) called "grassed modular grid pavement," which was installed to minimize the stormwater quantity and quality impacts of some or all of the paved surfaces on your property. Grassed modular grid pavement has the runoff characteristics of a lawn while providing the weight-bearing capacity of concrete pavement. The grassed surface not only minimizes runoff quantity, it helps to filter pollutants generating by vehicular use of the surface. The composition and area of grassed modular grid pavement as depicted by the flow control BMP site plan I and design details must be maintained and may not be changed without written approval either from the King County Water and Land Resources Division or through a future development permit from King I County. l ' Grassed modular grid pavement must be inspected after one major storm each year to make sure it is working properly. Prolonged ponding or standing water on the pavement surface is a sign that the system defective and may need to be replaced. If this occurs. contact the pavement installer or the King County Water and Land Resources Division for further instructions. The grassed surface of the pavement must be regularly mowed and maintained in a good condition. Bare spots must be replanted in the spring or fall. ,._ 2009 Surface Water Design Manual -Appendix C 1/9/2009 C-67 I