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I I /// Ill I I ;/; ill I I I I I I I I I I NE 1/4 SECTION 29, TOH.NSHIP 2J N, RANGE 5 E, BETHANY CORNER ( ' ' ' ~----,,.~· ' • i ' ' ' ' ' ' ,. ' // 5 : /· V-"~' I ; ' ,' : i c,----~--J r------1,r----~1,r---~--1 I I I I I I I I I I I ·.I I I I I I •1 I 4 I I j I I .l I : .... u : : ·-·~ : : ~ ~' : I I I I I I I I I I I I I I .I I I I I l I I I I I I 1 I L------~ L------~ L--··---~ r------·,. i ' r---.---1 ' ' ,--- i ' ' ' ' i i i i ' i ' ' . J: : ,I . 8 I ' ' ' . ' ' ' : ··"''' I .,,,,, " ' ' i ' ' ' ' i ' ' ' , __ l . ., .. ~~ I i ' ' ' i ' ' i ' i ' ' L ______ J : ~!'I:.>: : ' ' ' ' ' ' ' ' ' ' L ______ J c----~-1 ' ' : ~ ' ' i ' ' ' I : /I L ____ ~ I I I I I I W..11. I ' I ' 'r ~~r ' i ! t i i I I I I I I I I I I I I I I I I I I I I ;;-..,,j,• .. · i,;,-·- 1 ~~~:,~ WA TFR.&J!1WY NOTE: a%itHst::= = ~"t,. ci « 3 @ NORTH I I ,li_a11-~'" 6):··:;:;·-.,: ~, 1i i[j' [R K" J co•s/Ji'/;/1,,~ --u 1-A-NNNNNNN i ----'v·-· i lY' ,;;ii -~---,. ~- 0 I III.Ml".ID.Oll..., ·*r,><"''"''-'"·-•·"'·---·--.,,, 1 A ~ o-.-,--~ .., .eVl>ION !lY """' ..,,f'il --:: I •• .. -.. -=. I \=ii I ·-· -'' ·f'I *' CITY OF -, --1111111a11 RENTON I Pbrnono/e..;1a,,..;P"O,;, WoM O.pt . , ,~,~-,.,unF :vm ' . , ! l 1 --·--·---·-·-·------- NNNNNNNVW I I 3S 311. t/H.1 tJ.· t ;----, ' ' ' ' ' ' ' ' ' .. _____________ J ~------'!-<' J I -----, ' ' ' ' ' L _____________ J ~--·==-~. Hi;51;.. 1::13Nl::IOJ AN\fHl38 9 ~z oo §~ t ---------------·-·-·-·-·· Ii l@ ------~·--------'-/~ ----, • ' ' ' ~---------_____ ..,: r-------------, ' ' ' ' ' ' ' • ' ' L--------------' -, ' ' ' ' L __________ I • ----.;.--------- ' ' ' ' ' ' -'_--_--_-_-_-_--_-_-,_. --'"""..+-~~lirl! ! rl 111 ~~ I 11 "! I :! I ' ' n '-,,/Hf;-dj--------- NNNNNNNW'v 1:::13Nl:::IOJ ANVH138 L I ·~ I, oo,; -,, _.J I "" ·-i ~1 ~::: I ' r::::.~, ~ "" I~ I ·-' ~ --~- 1_ 0 "'" ' 0 \ I l D.R. STRONG CONSULTING ENGINEERS TECHNICAL INFORMATION REPORT for BETHANY CORNER SHORT PLAT 16433 & 16451111'" Avenue SE, Renton, Washington DRS Project No. 16062 Renton File No. PRE16-000651 Owner/Applicant Mary Nguyen 9102 SE 41 '1 Street Mercer Island, Washington 98040 Mark Seek 15233 Manion Way NE Duvall, WA 98019 Report Prepared by kit D. R. STRONG Consulting Engineers, Inc. 620 7'" Avenue Kirkland, WA 98033 (425) 827-3063 Report Issue Date December 20, 2016 ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report CITY CJF !:.:u,: ·: ;::: rr:~.:: l\.' !•~ ,-, DEC 2 2 ZOH: Bethany Corner Renton, Washington TECHNICAL INFORMATION REPORT BETHANY CORNER SHORT PLAT TABLE OF CONTENTS SECTION I ...................................................................................................................... 4 Project Overview ......................................................................................................... 4 Predeveloped Site Conditions ..................................................................................... 4 Developed Site Conditions .......................................................................................... 4 King County Area, Washington .................................................................................. 14 AgC-Alderwood gravelly sandy loam, 8 to 15 percent slopes .............................. 14 SECTION II ................................................................................................................... 16 Conditions and Requirements Summary ................................................................... 16 Conditions of Approval. .............................................................................................. 18 SECTION Ill .................................................................................................................. 19 Off-Site Analysis ........................................................................................................ 19 Task 1: Define and Map Study Area ...................................................................... 19 Task 2: Resource Review ...................................................................................... 20 Task 3: Field Inspection ......................................................................................... 29 Task 4: Drainage System Description and Problem Descriptions .......................... 30 Task 5: Mitigation of Existing or Potential Problems .............................................. 31 SECTION IV .................................................................................................................. 37 Flow Control Analysis and Water Quality Design ...................................................... 37 Existing Site Hydrology ......................................................................................... 37 Developed Site Hydrology ...................................................................................... 39 Performance Standards ............................................................................................. 42 Flow Control System .................................................................................................. 43 Water Quality Treatment System ............................................................................... 50 SECTION V ................................................................................................................... 52 Conveyance System Analysis and Design ................................................................ 52 SECTION VI .................................................................................................................. 61 Special Reports and Studies ..................................................................................... 61 SECTION VII ................................................................................................................. 62 Other Permits, Variances and Adjustments ............................................................... 62 SECTION VIII ................................................................................................................ 63 CSWPPP Analysis and Design (Part A) .................................................................... 63 SWPPP Plan Design (Part B) .................................................................................... 63 SECTION IX .................................................................................................................. 65 Bond Quantities, Facility Summaries, and Declaration of Covenant.. ........................ 65 ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Bethany Corner Renton, Washington Stormwater Facility Summary Sheet .......................................................................... 66 SECTION X ................................................................................................................... 68 Operations and Maintenance Manual ........................................................................ 68 APPENDICES ............................................................................................................... 69 Appendix "A" Legal Description ................................................................................. 70 Appendix "B" CSWPPP ............................................................................................. 71 Appendix "C" Bond Quantity Worksheet .................................................................... 72 List of Figures Figure 1 TIR Worksheet .................................................................................................. 6 Figure 2 Vicinity Map ................................................................................................. 11 Figure 3 Drainage Basins, Subbasins, and Site Characteristics ................................... 12 Figure 4 Soils ................................................................................................................ 13 Figure 5 City of Renton Topography Map ..................................................................... 21 Figure 6 City of Renton Coal Mine Hazard Areas Map .................................................. 22 Figure 7 City of Renton Flood Hazards Map ................................................................. 23 Figure 8 City of Renton Streams and Wetlands Map .................................................... 24 Figure 9 City of Renton Landslide Hazards Map ........................................................... 25 Figure 10 City of Renton Seismic Hazard Areas Map ................................................... 26 Figure 11 FEMA Map ................................................................................................... 27 Figure 12 King County iMap Drainage Complaints Map ................................................ 28 Figure 13 OffsiteAnalysis Downstream Map ................................................................ 33 Figure 14 Offsite Analysis Downstream Table .............................................................. 34 Figure 15 Predeveloped Area Map ................................................................................ 38 Figure 16 Developed Area Map .................................................................................... 41 Figure 17 Detention & Water Quality Facility Details ..................................................... 51 Figure 18 Backwater Analysis Map ............................................................................... 56 ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Bethany Corner Renton, Washington SECTION I PROJECT OVERVIEW The Project is the proposed subdivision of two parcels into nine single-family residential lots, per the City of Renton's (City) subdivision process. The Project is located at 16433 & 16451 111 1h Avenue SE, Renton, Washington (Site) also known as Tax Parcel Numbers 008800-0570 & -0560. The Project will meet the drainage requirements of the City of Renton Amendments to the 2009 King County Surface Water Design Manual (CORSWDMA). PREDEVELOPED SITE CONDITIONS The total existing Site area is approximately 79,710 s.f. (1.83 acres). The Site is currently developed with two single family homes, one trailer home, gravel driveways, one detached garage, a shed, a concrete foundation, and landscaping. The Site consists of a shallow grade to the southwest and is contains one Threshold Discharge Area (TOA). Runoff generated by the TOA gradually sheet flows east to southwest towards adjacent parcels to the west or is collected by a culvert in the southwest corner of the Site. Sheet flow over the west property line and culvert flow from the southwest corner of the Site form the two natural discharge locations for the Site. The two Natural Discharge Areas (NDAs) of the Site divide it roughly in half with the northern portion draining to the west and the southern portion draining to the cuvert. Sheet flow from the western property line is captured by Big Soos Creek on the adjacent parcels and is conveyed to the south. Runoff through the culvert in the the southwestern corner of the Site travels for approximately 55 feet in a westerly direction to a convergence point with Big Soos Creek. Flow from both NDAs converges within the Y. mile and therefore the Site can be considered to be within one TOA. The Project frontage currently drains to a series of ditches and culverts along 111 th Ave SE and converges with Big Soos Creek approximately 160 feet downstream. DEVELOPED SITE CONDITIONS The applicant is seeking approval to subdivide 1.83 acres into nine single-family residential lots (Project), with lot sizes ranging from approximately 5,948 s.f. to 7,119 s.f. All existing improvements located on the Site will be demolished or removed during plat construction. The project is required to meet the City's Flow Control Duration Standard -Matching Forested and Basic Water Quality treatment. This standard matches the developed Site flow durations to the flow durations of pre-developed rates for forested (historical) site conditions. These standards will be met through the proposed combination detention and water quality vault. The proposed impervious surface areas are as follows: half street frontage improvements consisting of a 5' sidewalk along 111 1h AVE SE, Road A, the nine new single-family residences and associated driveways, and Tract A, the storm water detention facility, will generate approximately 51,486 s.f. of impervious area (1. 18 acres). The Project will implement the restricted footprint BMP and the allowable impervious of each lot will be reduced by 10%. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page4 Bethany Corner Renton, Washington A section of non-target impervious surface along the north side of 111th AVE SE will be collected by the proposed detention facility. The facility has been designed with this section being proposed as an offsite flow-through area. This area will be modeled as impervious in both the predeveloped and developed scenarios. Proposed Site cover and surfaces are show in Figure 16, Developed Site Conditions. (See Section IV). The Project proposes to combine runoff from both onsite NDAs and the target frontage into one detention system and to discharge to the road-side ditch system just upstream of the confluence with Big Soos Creek. The existing natural discharge locations for the Site are not suitable for concentrated. No drainage easements are available for discharge to Big Soos Creek to the west. Discharge to the road-side ditch connects to a manmade public conveyance system. The proposed discharge location is well within the Y. mile of the natural discharge locations. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 5 Bethany Corner Renton, Washington FIGURE 1 TIR WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner: Mark Seek and Mary Nguyen Phone: (206) 315-8130 Address: 15233 Manion Way NE, Duvall, WA98019 9102 SE 41'' Street, Mercer Island, WA 98040 Project Engineer: Company: Phone: Jonathan S. Murray, P.E. D. R. STRONG Consulting Engineers Inc. (425) 827-3063 Part 3 TYPE OF PERMIT APPLICATION ~ Landuse Services Subdivision/ Short Subdivision / UPD ~ Building Services: M/F / Commercial / SFR ~ Clearing and Grading D Right-of-Way D Other: Part 5 PLAN AND REPORT INFORMATION Technical Information Report Type of Drainage Review !Full! I Targeted / (circle): Large Site Date (include revision dates): December 15 2016 Date of Final: I Part 6 ADJUSTMENT APPROVALS ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Part 2 PROJECT LOCATION AND DESCRIPTION Project Name: Bethany Corner City Permit#: PRE16-000651 Location: Township: 23 North Range: 05 East Section: 29 Site Address: 16433 & 16451 111•h Avenue SE, Renton, WA Part 4 OTHER REVIEWS AND PERMITS D DFWHPA D Shoreline Mngmt D COE404 ~ Structural D DOE Dam Safety RockeryNault D FEMA Floodplain D ESA Section 7 D COE Wetlands D Other: Site Improvement Plan (Engr. Plans) Type (circle one): Date (include revision dates): Date of Final: Page 6 !Full! I Modified / : Small Site Bethany Corner Renton, Washington Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket Description: (include conditions in TIR Section 2) Date of Approval: Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes/ No Describe: Monitor discharge location Start Date: TBD during construction. Completion Date Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: =B=e~ns=o=n~----------------------- Special District Overlays: ~N=/A~---------------------- Drainage Basin: Green/Duwamish River Watershed Stormwater Requirements: Flow Control Duration Standard -Matching Forested and Basic WQ treatment Part 9 ONSITE AND ADJACENT SENSITIVE AREAS ~ River/ Stream: Big Soos Creek D Lake D Wetlands D Closed Depression D Floodplain D Other Part 10 SOILS Soil Type AgC ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis D D D D D D Slopes 8-15% Steep Slope Erosion Hazard Landslide Hazard Coal Mine Hazard Seismic Hazard Habitat Protection Erosion Potential Moderate to Severe Page 7 Bethany Corner Renton, Washington D High Groundwater Table D other D Additional Sheets Attached D Sole Source Aquifer D Seeps/Springs Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION I SITE CONSTRAINT ~ Core Reguirement #2 -Offsite Anall£sis ~ SEPA ~ Sensitive Area Buffer D D Additional Sheet Attached Part 12 TIR SUMMARY SHEET Threshold Discharge Area: Site com~rised of one TOA (name or description) Core Requirements (all 8 apply) Discharge of Natural Location yes Oftsite Analysis Flow Control (incl. facility summary sheet Conveyance System Erosion and Sediment Control Maintenance and Operation Financial Guarantees and Liability Water Quality (include facility summary sheet) Special Requirements (as applicable) Area Specific Drainage Requirements Floodplain/Floodwav Delineation ©2016 D. R STRONG Consulting Engineers Inc. Level One Downstream Analysis Number of Natural Discharge Locations: 1 Level: 1 I 2 / 3 dated: 09/28/2016 Level: 1 I 'l,. I 3 or Exemption Number Small Site BMPS Restricted Footi;irint Spill containment located at: TBD ESC Site Supervisor: T/B/D Contact Phone: T/B/D After Hours Phone: T/8/D Responsibility: Private I Public If Private, Maintenance Log Required: Yes I No Provided: Yes I No Type Basic I Sens Lake/ Enhanced Basic I Bog or exemption No. Landscape Management Plan: Yes/ No Type: CDA / SDO I MOP/ BP I LMP I Shared/ None Name: T""e: Maier I Minor/ Exemption/ None Page 8 Bethany Corner Renton, Washington 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: N/ A Source Control Describe Landuse: (comm. I industrial landuse) Describe any structural controls: Oil Control High-use Site: Yes/ No Treatment BMP: Maintenance Agreement: Yes I No with whom? Other Drainage Structures Describe: Runoff will be collected and conveyed to the wet-vault detention facility located in Tract A. Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION [SJ Clearing Limits [SJ Stabilize Exposed Surfaces [SJ Remove and Restore Temporary ESC [SJ Cover Measures Facilities [SJ Perimeter Protection [SJ Clean and Remove All Silt and [SJ Traffic Area Stabilization Debris, Ensure Operations of Permanent Facilities [SJ Sediment Retention [SJ Flag Limits of SAO and open space [SJ Surface Water Collection Preservation areas D Other D Dewatering Control [SJ Dust control [SJ Flow Control Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch Flow Control ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Water Qualit Page 9 Bethany Corner Renton, Washington ~ Detention Wet-Vault D Infiltration D Regional Facility D Shared Facility ~ Flow Control BMPs Restricted Footprint D Other Part15 EASEMENTS/TRACTS D Drainage Easement D Covenant D Native Growth Protection Covenant ~ Tract D Other: D Biofiltration ~ Wetpool Wet-Vault D Media Filtration D Oil Control D Spill Control D Flow Control BMPs D Other Part 16 STRUCTURAL ANALYSIS ~ Cast In Place Vault D Retaining Wall D Rockery > 4' High D Structural on Steep Slope 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 knowledge the information provided here is accurate. ©2016 D. R STRONG Consutting Engineers Inc. Level One Downstream Anatysis /2 2tJ 28/~ ned/Date Page 10 Bethany Comer Renton, Washington FIGURE 2 VICINITY MAP ,.. __ .,, _____ .... ___ ..... _., ............ ___ .. ,,_...,. ----... ---.. --.. _ .. _ ··-----··-,, ....... _,-.,,.,._,....., . ...,_ ... _ .......... -.....~--...... -~ ....... -_. ... -..,::. ......... .-__ _,. ... ...,._ .... __ .. .,_""""'-_,.,. __ _ .... _._ __ .,. __ ...... 11o1--.. -.... .,, ........... --~, __ ...,,,,( ... c..n:, o.i.: 10/31/20!& tictlll The information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. King County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. King County shall not be liable for any general, special, indirect, incidental, or consequential damages including, but not limited to, lost revenues or lost profits resulting from the use or misuse of the information contained on this map. Any sale of this map or information on this map is prohibited except by written permission of King County. ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 11 Bethany Corner Renton, Washington FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 12 Bethany Corner Renton, Washington NATURAL DISCHARGE AREA 1 FOR THE SITE IS ACROSS THE WESTERN PROPERTY LINE NATURAL DISCHARGE AREA 2 FOR THE SITE IS PIPE FLOW IN A SOUTHWESTERLY DIRECTION ? SITE 79,710 (1.83 AC) 155 LF FROM FARTHEST UPSTREAM END TO DETENTION VAULT INLET L _____ J ___ _ NOA f" -E ~J__J I I I I r-------r-----:---t-1 NDA2 -E ? CONSTRUCTION AND / DEVELOPED RUNOFF WILL BE STORED IN A DETENTION VAULT ,; ' / / ~ I , I j I I I I ~ ' r ~ ( r-- ·~ ~ ~ :b. s:: n, ~ L @ NORTH GRAPHIC SCALE 0204060 ~ .. i ~ i ~§ ii!.; ! ; i I ! Ci ~ ~ ~ ~ ~ ~ ~ ~ ~ ffi i,;::: (j ~ ~ . ~ ~ I ~ 0 . ~ (j !JJ ~ t:: ~~ Cl) !l:: ~ ~ C':I !(j :s ~ ~ <(~ " 8~ili ~ ~:::~ ~ ~i~- ~ ~--;c: co ~ !(j ~ ~Q: Cl) ... ~ ci, ~ ~ ~ .... ~ DRAFTED BY: CYW OE51GNEO BY: CYW PRQ..£Cr ENGINEER: JSM DATE:: 12.15.16 PRo..ECT 1'10.: 16062 1 INCH = 40 FT. I 3 R: \2076 \0 \ 76062\J\Orowings \Plots \Figures \OJ-JBASINS_ 16062 dwg 7 2/27/2076 71: 37: 27 AM COPYRIGHT© 2016. D.R. STRONG CONSULTING ENGINEERS INC F<GURE, I FIGURE 4 SOILS Seil ~g County An>., Wuhingicn WYnnJ: Sol ~ may not be valid a tHs scale. ...,Sc*;t;(£lf -c,,A-(8S aU'),,..._ 0 ,0 Xl 0 Xl ~ ~ ~ ...,pqo:im: __ °"""-'\M'.l5&4 &tjo,bclJ!kh,ollr<w:;i;&o lbtunl RHOU<CH ConsorvJ11ion s ..... ic. ©2016 D.R. STRONG Consulting Engineers Inc. Lev el One Dow nstream Anal ys is Wtb Soi S<nty NalicnJII eoop.atiw Soll Surwy Page 13 -- ~ ~ ..-,..n':V-. R ~ !l t Q § f : I I ! I I !'I I i ! I I ..,..vv,,. -• b ~ U3131no1a PJ111f l ofl Beth any Corn er Renton , Washi ngton KING COUNTY AREA, WASHINGTON AGC-ALDERWOOD GRAVELLY SANDY LOAM, 8 TO 15 PERCENT SLOPES a) Map Unit Setting • National map unit symbol: 21626 • Elevation: 50 to 800 feet • Mean annual precipitation: 20 to 60 inches • Mean annual air temperature: 46 to 52 degrees F • Frost-free period: 160 to 240 days • Farmland classification: Prime farmland if irrigated b) Map Unit Composition • Alderwood and similar soils: 85 percent • Minor components: 15 percent • Estimates are based on observations, descriptions, and transects of the mapunit. c) Description of Alderwood (1)Setting • Landform: Ridges, hills • Landform position (two-dimensional): Shoulder • Landform position (three-dimensional): Nose slope, talf • Down-slope shape: Linear, convex • Across-slope shape: Convex • Parent material: Glacial drift and/or glacial outwash over dense glaciomarine deposits (2) Typical profile • A -0 to 7 inches: gravelly sandy loam • Bw1 -7 to 21 inches: very gravelly sandy loam • Bw2 -21 to 30 inches: very gravelly sandy loam • Bg -30 to 35 inches: very gravelly sandy loam • 2Cd1 -35 to 43 inches: very gravelly sandy loam • 2Cd2 -43 to 59 inches: very gravelly sandy loam (3) Properties and qualities • Slope: 8 to 15 percent • Depth to restrictive feature: 20 to 39 inches to densic material • Natural drainage class: Moderately well drained • Capacity of the most limiting layer to transmit water (Ksat).· Very low to moderately low (0.00 to 0.06 in/hr) • Depth to water table: About 18 to 37 inches • Frequency of flooding: None • Frequency of ponding: None • Available water storage in profile: Very low (about 2. 7 inches) (4)1nterpretive groups • Land capability classification (irrigated). None specified • Land capability classification (nonirrigated): 4s • Hydrologic Soil Group: B • Other vegetative classification. Limited Depth Soils (G002XN302WA), Limited Depth Soils (G002XS301WA), Limited Depth Soils (G002XF303WA) • Hydric soil rating: No ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 14 Bethany Corner Renton, Washington d) Minor Components (1) Everett • Percent of map unit: 5 percent • Landform: Eskers, kames, moraines • Landform position (two-dimensional): Shoulder, footslope • Landform position (three-dimensional): Crest, base slope • Down-slope shape: Convex • Across-slope shape: Convex • Hydric soil rating: No (2)1ndianola • Percent of map unit: 5 percent • Landform: Eskers, kames, terraces • Landform position (three-dimensional): Tread • Down-slope shape: Linear • Across-slope shape: Linear • Hydric soil rating: No (3)Shalcar • Percent of map unit: 3 percent • Landform: Depressions • Landform position (three-dimensional): Dip • Down-slope shape: Concave • Across-slope shape: Concave • Hydric soil rating. Yes (4)Nonna • Percent of map unit: 2 percent • Landform: Depressions, drainageways • Landform position (three-dimensional): Dip • Down-slope shape: Concave, linear • Across-slope shape: Concave • Hydric soil rating: Yes ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 15 Bethany Corner Renton, Washington SECTION II CONDITIONS AND REQUIREMENTS SUMMARY The Project must comply with the following Core and Special Requirements: • C.R. #1 -Discharge at the Natural Location: Existing drainage discharges the Site at one location, maintaining one TOA. The topography indicates that all stormwater runoff leaves the Site as sheet flow across the west property line. Runoff is collected by Big Soos Creek which is located on an adjacent property to the west. Developed runoff will require discharge to a conveyance system. Discharge from the project will be directed south to the existing conveyance system along 111th Ave SE. This discharge location converges with flow from the NOA within the Y. mile. • C.R. #2 -Offsite Analysis: Analysis is included in Section Ill. The Analysis describes the Site's runoff patterns in detail. • C.R. #3 -Flow Control: The Project is required to adhere to Flow Control Duration Standard -Matching Forested site conditions. One detention/wetvault will provide flow control as required for the new and replaced impervious and pervious surfaces. The Site is required to "match the flow duration of pre-developed rates for forested (historic) site conditions over the range of flows extending from 50% of 2-year up to the full 50-year flow," (City of Renton 2009 Surface Water Design Manual Amendment, Sec. 1.2.3.1 ). A detention vault will accommodate this requirement. • C.R. #4 -Conveyance System: New pipe systems are required to be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a "severe flooding problem" or "severe erosion problem" as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. This analysis is shown in Section V. • C.R. #5 -Erosion and Sediment Control: The Project will provide the seven minimum ESC measures. A temporary erosion and sedimentation control plan is presented as part of the engineering construction plan set. • C.R. #6 -Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and Maintenance Manual will be included in Section X at the time of construction plan preparation. • C.R. #7 -Financial Guarantees: Prior to commencing construction, the Applicant must post a drainage facilities restoration and site stabilization financial guarantee. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 16 Bethany Corner Renton, Washington For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 -Water Quality: The Project is required to provide basic water quality treatment. A combined detention/wetvault will accommodate this requirement. • S.R. #1 -Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 -Flood Hazard Area Delineation: Not applicable for this Project. • S.R. #3 -Flood Protection Facilities: Not applicable for this Project. • S.R. #4 -Source Control: Not applicable for this Project. • S.R. #5 -Oil Control: Not applicable for this Project. • S.R. #6 -Aquifer Protection Area: Site not located within zones 1 and 2, therefore not applicable for this Project. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 17 Bethany Corner Renton, Washington CONDITIONS OF APPROVAL Bethany Corner PRE16-000651 TBD ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 18 Bethany Corner Renton, Washington SECTION Ill OFF-SITE ANALYSIS LEVEL ONE DOWNSTREAM ANALYSIS DISCLAIMER: This report was prepared at the request of Mark Seek and Mary Nguyen for the 1.83 acre parcels known as a portion of the Northeast Quarter of Section 29, Township 23 North, Range 5 East, W.M., in King County, Tax Parcel Numbers 008800-0570, & -0560 (Site). D. R. STRONG Consulting Engineers Inc. (DRS) has prepared this report for the exclusive use of DRS, the owner, and their agents, for specific application to the development project as described herein. Use or reliance on this report, or any of its contents for any revisions of this project, or any other project, or by others not described above, is forbidden without the expressed permission by DRS. TASK 1: DEFINE AND MAP STUDY AREA This Offsite Analysis was prepared in accordance with Core Requirement #2, Section 1.2.2 of the 2009 King County Surface Water Design Manual and City Amendments as adopted by the City of Renton (Manual). The Site is located at 16433 & 16451 111 th Avenue SE, Renton, Washington. The Project is the subdivision of two parcels into nine single-family lots. See Figures 5 through 12 for maps of the study area. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 19 Bethany Corner Renton, Washington TASK 2: RESOURCE REVIEW • Adopted Basin Plans: The City of Renton and King County Department of Permitting and Environmental Review (DPER) and Department of Natural Resources and Parks (DNRP) do not have a specific plan for the East Lake Washington Drainage Basin. • Finalized Drainage Studies: No available applicable drainage studies at this time. • Basin Reconnaissance Summary Reports: None available. • Comprehensive Plans: Renton's Comprehensive Plan, adopted on June 22, 2015, effective July 1, 2015. • Floodplain/Floodway (FEMA) Map: No floodplains exist on site, See Figure 11. • Other Offsite Analysis Reports: None available within adjacent properties. • Sensitive Areas Map Folios, City of Renton GIS: See Figures 6-10. The City's GIS system shows a wetland on Site. A Wetland Assessment dated June 2, 2016 was prepared by Mark Rigos, P.E. This assessment found that there were no areas on the Site which met the definitions of wetlands. • DNRP Drainage Complaints and Studies: Per King County Water and Land Resources Division, there is one complaint within the downstream paths, within approximately one mile from the Site within the last 10 years. See Figure 12. • USDA King County Soils Survey: See Figure 4 • King County Wetlands Inventory: Vol. 2 East (1990) -Wetland 5401 (category 2) identified within one mile of the downstream path. See Figure 8. • Migrating River Studies: The Site is not located near the channel migration zones of Cedar River, Toll River, Raging River, Snoqualmie River, or Green River. • King County Designated Water Quality Problems: Per the Washington State Water Quality Assessment 303(d)/305(b) Integrated Report current as of 2012, there are no water quality problems within 1 mile downstream of the Site. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 20 Bethany Corner Renton, Washington FIGURE 5 CITY OF RENTON TOPOGRAPHY MAP I City of Renton Print map Template . lh SI SE 1641h St SE 1641h St SE 164th SI .uu •....:.. 10921 10927 10935 10945 10955 w <fl me >" "' " £ :: - 16411 t 16433 ," , V, <' 0 Site " Notes NoM C 16473 . 0 126 0 64 128 ~- ~ _ 19&4 _Web_ M«'taior _ Auxiliary_ Sphere CltyofRetuOil('.,} Finance & IT Division 16451 ' 16459 16467 164SJ Legend City and Col.M,ty Boundary c·1 Cilyoff'lenlon Addreues "'""" -· 100' Primary 100' Intermediate -20' Primary 20' Intermediate lnt'oma1lon TIChnoklgy • GIS RentonMapSuppor1GIRenloowa.f111¥ 10/31/2016 16404 16410 16420 11123 0 16438 " " , ~ 0 .J C 16446 16442 16445 164Sl 16466 11116 16474 11130 ... ,.. . ...... . ..., ~C ltltHII f' I . lh,~ map as a-"~' gec.er~,Sd s·at c cd~sl ~cro ar, l~IN'6! map~,~g s-te a•,d es fu, C?fo0 t,nce-Mi\' D~t., 1~,1~,..,, ,~~, app,,n, ,:,n 1h1s "'"" n1ar"' may oot r.: a.:,;u,~I~. c,u,;;i,t 0' uln~,,.,se ,~Laol~ THIS MAP IS NOT TO BE USED FOR NAVIGATION I ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 21 Beth any Corner Renton, Washington FIGURE 6 CITY OF RENTON COAL MINE HAZARD AREAS MAP I City of Renton Print map Template I .o 10952 "/'·1700 1710 1740 10928 112l0 1810 I SE 164lt1 St 2607 SE 16~!h St SE 164!h St = 16402 10831 10911 10945 109'55 16404 1113'!1 16410 t 16410 "' 16418 16417 "' 16420 < 1613 16411 16422 I 16420 11123 > < ·-C 16427 W 16430 1-.-.,, ;; 10744 16432 "' • • 16438 -16439 > > 16511"1 St <( Site <( 16500 16443= 16446 ~ 107:J9 16508 "' 16~1 -16446 16442 1644'!1 0 w 16449 -- "' 16452 < 16514 164'!17 16457 > 16517 <; 16022 16465 "' C 16460 16473 16467 16466 16-46l "' ;; • 0 > -10808 16474 11116 16471 < 10740 10814 11130 C • 16482 16483 s::. ~, 16475 ;; 9th S1 SE 29!h St iOi,ii, , 16603:;:: t64S6 1f218 11222 1709 ,,,. 11214 11226 1717 16606 16606 11210 11242 • "' 11204 SE 10tiH'I Pl ~. "' 16611 ~. • > "' '<; 21,,2 <( a 16618 16625 16627 16620 16621 "' 3001 C ... 'b " ~ (I) 3008 0 .. 16639 -(' 3016 3007 3013 16634 16644 \ 16627 11122 16651 17241730 10940 11124 3100 10912 16650 11212 16655 16653 1m 11126 SE 168!!": SI SE. 168th St SE 16Emi St 11215 16803 16801 16810 10907 10933 11101 11207 10911 1111 ~ 1681h~ 10915 .. ....,. ~ 16813 10917 11129 --.... City .-id County Boundary -..... ~ .,,._ 0 ......... ·-· COU'lline • ... , .. 0 "' 256fMI D -AA~ INGS_ 1$1&4_ Web_Merc.to(_Au,,i11")'_ s~ llftCLASSIFIEO Clty•,Ret1ton~, ~T~-G· T0 ,s ""f· .-s > ~,e 0 ~Mc•:o•~~ .,~,,.· ~ .rro:i'f-,, M l.ol~rn~t marp,n'] ~,!~ aca, RertlorMa~.go'I s !:,, ,~rc·,ac<> "":i [lat,, l:wts IOa, opp~e, o~ h>s "'"I· r· a,y O< 01.>y "cl ~c cc,a!c cc,w~: c·10H,c=><,re',ot,lc Finarice & IT Division 10011201e THIS MAP IS NOT TO l!IE USED FOR NAVIGATION ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 22 Bethany Corner Renton, Washington FIGURE 7 CITY OF RENTON FLOOD HAZARDS MAP I City of Renton Print map Template I Q 10952 1740 10928 U'J1700 1710 1810 11230 2607 SE 1641h St SE 164tr. St SE 164th St = 16402 10831 10'911 10945 10955 16404 11135 t 16410 16410 w 16-418 u; 16417 16420 0 1613 16411 16422 I 16420 11123 > < C w 16427 l.!..! 16430 16433 ;; u; "' -10744 16432 • -• 16438 16439 > Site > 165U1 St <( <( 16500 16443 c. 5 16446 10739 16508 a; 1645 -16446 16442 16445 0 w 16449 -.- "' 16452 Q 16514 164~ 16457 > 16459 16517 .:t 16522 16465 w C 16473 16467 16466 "' ;, 16460 1646-3 Q 0 > -10808 16474 11116 16471 <( 10740 10814 11130 16475 ~ • 16482 16483 n, 9!1'l St SE 29th St Sc iUG(;, , 16603::: 16486 1121811222 1709 1n, 1121,4 11226 11'17 16606 11210 112-42 • 16606 U) 11204 SE 1tltHf\ Pt <!?& \I) 16611 ~-Q > a> 'I, 2932 <( 16620 ,ii 16618 16625 16627 16621 .,, 3001 C ,j'' 0-a; f/l 3008 0 16639 -0 3016 3007 3013 16634 .. 16627 16644 \ 11122 166~ 17241730 10940 11124 3100 10912 16650 11212 1 Ei655 16653 1n1 11126 SE 1681n St SE 166th St SE 168th St 1121.5 16803 16801 16810 10907 10933 11101 11207 10911 11115 16811,~ 1091~ .. ~-~ ~ 16813 10917 11129 NolH Logond -City and County Boundary -~·· City~~ ~ .~ 0 .......... Parcels flil FIOodway • Special Flood Hazard Areas (100 206 0 ,,. 256 FNI yearftood) INGS_ 1984_weti_ Mert:NOl" _ Auxillary _ Sphere r~ Other Flood Areas (Zone X-500 year flood) City of R.eti(Ofl (,~ lnfom,doft Tite"**'IY -GIi Toas n,~e ,sacs~· ~eerated s!~t•c cut;J~t frora 311 l,il~m~I n ~pr,1r11 ~:I~ and RentonMapS\.IIP0f10Rerotonwll.p ,c le< ,~J,•,enoa ""'I' Data la·1~rs t·~t ~prr,J, oe tr» n,ap ~,e~ c< rri.1y CIC1 N"- <k:~u,a·~ cunMI. ~, Llt:,~,v,,se rni,aD!e Finance & IT Division 10f.31f.2016 THIS MAP IS t-DT TO BE USED FOR NAVIGATION ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 23 Bethany Corner Renton, Washington I I FIGURE 8 CITY OF RENTON STREAMS AND WETLANDS MAP City of Renton Print map Template SE 164th St = SE 164th St 11230 ~. . . . 1710 SE 164th S! 1740 1810 10928 109~ 11135 11307 16402 10831 10811 1094510955 16410 w 16408 <ll & 16417 16420 > 16418 16422 16-404 16410 16411 tj 16420 .-----... 11123 <( ~ 16427 w 16430 U) 16433 ~ ;; 16428 16432 16500 16508 164,19 ~ .,: 16443 5 16446 "' _.~!!'-·..,·..,-·Site ~~., ---i - 164-49 0 <Q<if\, 16~0/.~.:'~J 16473 16474 ~) 16514 16457 16522 16465 10808 10814 t 16482 SE 291h St 1709 1720 1717 16606 uJ <ll & > 16446 16452 16459 16467 16466 16483 S:: 16611 11116 • --·· ... 1 lUt'\11 L 16486 16606 16442 16445 16457 11130 11218 11222 11214 11226 11210 11242 11204 SE 1t:HiU'I Pl • 16618 2932 "' 16620 1 "', 16618 1662:5 16627 16630 3001 ~ a; 0 - 3016 3007 3013 17241730 3100 1n1 SE 168th St 16810 16634 10912 SE 1681h St 10907 10933 10911 10940 11101 Cl .. 16644 ; 16650 11115 10915 Notes Nono 0 ~56 0 128 256 FNI ~-1984 _ Web_ Mert:ailor _ ,1,uidllary _ Sphere City of Reif(Qfl '''.') Finance-& IT Division 10917 10945 legond City •nd County Boundary [:] City DI Rffllon ........... Parcels Stre•ms (Clnlified) -TrPeS -Typ,F -TypaNp '"""' .,._1kln Technology•GIS RentonMapSupportGRentonwa.p 10/'31/2016 11122 11124 11126 11212 16639 16U1 16655 16642 16654 SE 166th St 11207 11129 11215 16803 16804 11313 1681h~ 16812 " 168'21 J;. Tn,s ,i,ac ,s a Js<,• ~e-·e•at~J sla:-c cdp~: r,c,, ~" 1,,iemet rra~o,ng M~ a·~ t-\ fo, rtf.,'1lnc-:, o,,ly Pala l~yer> t 0 Jt app,,,,, on Thi'". niap m~t o, rMy 001 t:,\ a;;~wn:e. CuFJent. <lf orn~,-....,,e r~l,abl~ THIS MAP IS t«>T TO IE USED FOR NAVIGATION I ©2016 D. R STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 24 Bethany Corner Renton, Washington FIGURE 9 CITY OF RENTON LANDSLIDE HAZARDS MAP I City of Renton Print map Template 11122 (' 10932 i '1, t .. · )> < 1814 1903010936 11126 0 fll1700 17'10 1740 1810 10928 109~ ldemy 2607 S 27?h St 1523 1613 10724 10744 SE 165th St 1525 10732 "' "' 0 > 16521 16517 c( C 1508 ii 0 - 1509 10740 S 29th St 16611 Q. "', o? 16621 .,, " SE 164111 St 16402 10831 16410 16418 16422 16432 16417 16427 16439 SE 10911 16420 ~ 16430 0 > < 16500 16443 £ 1 6446 16508 16449 16514 16457 16522 16465 10808 10814 SE 29th St 1709 1115 1717 2932 3001 "' 0 - 16460 16474 1 16482 16606 "' <!) 0 > < C of 16620 {I) 3008 0 - 16627 3016 16653 3100 3007 3013 17241730 ugend 16634 1 0912 164\h SI SE 164th St = 10945 10955 16404 16410 16411 I 16420 11123 16433 U-l "' Site 0 16438 > < C 16451 -16446 16442 16445 .- 16452 16457 16459 16473 16467 16466 11116 11130 16483 s:: . --. ...,, tlH•LI! •. 16486 1121811222 11214 11.226 16606 11210 16611 11204 SE 1ti .. 16618 .. 16625 ,J''I, .. ('I 16644 \ 11122 10940 11124 16650 ..... 11212 Notes NoM City and County Boundary 0 '"' 0 128 256f"4 CltyofRe.ttton,~·) Finance & IT Division -[:l Cty ol l'wnlon AddresS&S Parcels Llndllide • ..'UIYHIGH • ""'" E:J """""" UNCLASSIFEO lnfo.-don TKhllek,fy • GtS RentonMap,SupportG:Rentonwa.p 10/31/2016 ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 25 Tm• m2p 1s 2 ·_;•er \;P",A1a!ej s!a:,c m,lp,,t fir.ca "" lnlPrn~t rr ~rp1r11 ~~e g 1d i,; t~r ref"r~nce c.n~· D~la i,,,ers :031 ~~~Mr M 1'".,s n,ap ~'"Ye< m~y .-.cl~~ a-ccura;e. ccifl"e~t ,,,. ~n~cr,,sa rnl,able THIS MAP IS NOT TO BE USED FOR NAVIGATION Bethany Corner Renton, Washington FIGURE 10 CITY OF RENTON SEISMIC HAZARD AREAS MAP City of Renton Print map Template 11122 '6 10932 ~ Q ~ 11126 :,, 1814 1903010936 < • 10952 1740 10928 U::1700 1710 1810 rdemy 2007 SE 16tilh St SE 164th St SE 164th St = 16402 10831 10911 10945 10955 16404 S 27th St 16410 16410 16418 16417 16420 1523 1613 16411 16422 I 16420 11123 16427 ~ 16430 10744 16432 1on4 16439 " > rn5tti St 16500 ,( SE 16443~ 16446 16508 0, 1525 10732 0 w 16«9 - 16433 u..; "' " 16438 Site > <( ic ~ 16446 16442 164' ~ 16445 .- "' " 165,14 16457 > 16521 16517 < 16465 ~ 16522 1508 s 16460 16452 16457 16459 16473 16467 16466 0 -10808 16474 1509 10740 10814 • 16492 S 29th St SE 291h SI 11116 11130 16483 Sc IUC.\i, ('' 16486 11218 11222 1709 1725 11214 11226 1717 16606 U) 16611 <9$ "' "• " > o., 29'2 ,( .,, ~ 16620 16621 3001 0-a i:., 3003 0 - 16606 11210 16611 11204 SE 1ti ., 16618 .. 16625 ,I''\ C, 16644 \ 11122 3016 3007 3013 16634 16627 17241730 10940 11124 16653 3100 10912 16650 ..... 11212 -~nd -City and County Boundary 0 256 0 126 256 l"Nl WGS _ lN.ii_Web_ Mercalof_ Auxlil,ry _ Sphere City of Rettton 'c'J Finance & IT Division -:-·i L, CitJo dRefllon Addresses Parcels -...... ra Seismic Hazard Arns lnflmnadon Tedlnoiogy • GIS ~d<M ti pS :s IORentonwa.p 10/31/2016 ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 26 fo:~ map u; a"''" y~n•r•l~J •l•\.c Wlpa: r,01·1 "" lr1'-~""'I n,opo:n~ •Jlle 0:.,1 ,s ;,,, -~1~,eec~ nnl)' lla:a lay~r, ,oa• aap,.ar ~n 1111s mar m~)' <>: '!"ay not t-..- Jc~u,,1'~. Ullr\O',I. er e>therw,,~ .-,,; J~·e THIS MAP IS NOT TO BE USED FOR NAVIGATION Bethany Corner Renton, Washington NTY OF RENTON 530088 ZONf X s·~ ' ' 29 FIGURE 11 FEMA MAP CITY or RENTON KING COUNfY Site (Approximate) CITY OF RENTON ,, 530088 // / m ARE.-'\.S ~i ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Al'PilO~iMATE ~CO.IE ;N fH I ~ 0 "" Page 27 / 1111 NATIONAL ROOD INSUIIANCE PROG~~ 1 1 . 11FIRM Ii FLOOD INSURANCE RATE MAP KING COUNTY, WASHINGTON AND INCORPORATED AREAS D D MAP NUMBER J 53033Cll979 F i MAP REVISED: MAY 16, 1995 LEGEND WF< 1-,: llOOI) !I\L~~{) ,,~f\~ IM Nl)\111! B> 11•>--\l \~ l"!lllli! ION( .. ZONf -.1 ZONE ,IIH ZONf ,t,t9 l • I~ ,,,,.,,,.,, '""' I",.,. ,,._., la :::~:.i. ,,,~:·::' ,1::~· ,,,.,. "' ''"""'"" ' tom v '"·'·'·' '"' M'• "'"" ZON( VI! ,.,..,_; •,.,1 •·< ,.,. 1,,•,•d ,._.. ""'' ''""'"'' ,,.,., 1!000\\\\ .\Rt\', 1'1 lOM N OTHt~ FlOOll \~l\S -.. " ' --·~·-,, ..... ., ,, Zotll lt ••· ,..,_,, ~•· ,.,,• Bethany Corner Renton, Washington FIGURE 12 KING COUNTY IMAP DRAINAGE COMPLAINTS MAP King County iMap . ,..,..,...,,..,,,._..,.,. ____ .,IQ'tc,a.,,,,....,...,1,...-:ir.....-.... ......,,._ ........ ,...,.!Cf1~--,.--•--•-•-N •» __ ,_...,.._., .... »N-<I'..,,_..,,...-...___ A ___ • ._...., ......... ~~-1 ... N'M"'llr""-'·-N,n::_;.. ' ----"""""-'"' _ _..... .... .---~--... -,, ..... ____ .., ...... ""'1 .......................... ,.,.,... ...... __ ., .._,.......,,,~¢ul;/ Datt: f0'31i201~ Note,: Location Com laint Year Descri tion ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis = Jt2 -• • f---J.1129 -. - Page 28 Legend D • • • • • • • • C Parcels Bonded Commercial-MF Commercial-SF Consruction DOT FMD Regional Rt1identi1I Drainage complaint• Bethany Corner Renton, Washington TASK 3: FIELD INSPECTION UPSTREAM TRIBUTARY AREA Upon evaluation of the upstream area through examining COR topographic map (see Figure 5) and by conducting field reconnaissance on March 21st 2016, the upstream tributary area for the Site is considered negligible. The parcels to the north and south sheet flow to the west, and a swale exists in the right of way of 111 th AVE SE, conveying runoff to the south, away from the site. GENERAL ONSITE AND OFFS/TE DRAINAGE DESCRIPTIONS The Site is contained within one Threshold Discharge Area (TDA). Runoff from the Site sheet flows over the west property line and is collected by Big Soos Creek, which is flowing in a southerly direction. There also exists a Natural Discharge Area (NDA) which consists of a 12 inch reinforced concrete pipe in the southeastern corner of the Site which conveys storm water approximately 55 feet before sheet flowing westerly and converging with Big Soos Creek. The convergence point for the two NDA's is approximately 85 feet downstream from the Site. Big Soos Creek is conveyed through a series of culverts, swales, and as channel flow before discharging into an unnamed wetland approximately Y, mile downstream. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 29 Bethany Corner Renton, Washington TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DRAINAGE SYSTEM DESCRIPTION The downstream analysis is further illustrated and detailed in the Downstream Map Figure 13 and Downstream Table Figure 14. The drainage area is located within the East Lake Washington -Renton Drainage Basin. The drainage area was evaluated by reviewing available resources described in task 2, and by conducting a field reconnaissance on October 28th, 2016 under overcast conditions. DOWNSTREAM PA TH 1 "A 1" is a Natural Discharge Area (N DA) for the Site. It is located along the western property line (±0). From Point "A1" to Point "B1'', runoff continues to flow west as sheet flow over till grass. No concentrated flow was observed (±0'-45'). Point "B1", runoff is collected by Big Soos Creek. (±45'). From Point "B1" to Point "C1", runoff is conveyed in a southerly direction as channel flow via Big Soos Creek. Moderate flow was observed (±45'-502'). Point "C1" is the inlet of a 12" diameter Reinforced Concrete Pipe (RCP). Did not observe. (±502'). From Point "C1" to Point "D1", runoff is conveyed easterly as pipe flow via 12" RCP. Moderate flow observed (±502'-807'). Point "D1" is the outlet of a 12" diameter RCP. Moderate flow observed. (±807'). From Point "D1" to Point "E1", runoff is conveyed southerly as channel flow via a 2' tall and 3' wide swale. Moderate flow observed (±807'-813'). Point "E1" is the inlet of a 12" diameter RCP. Moderate flow observed. (±813'). From Point "E1" to Point "F1 ", runoff is conveyed in a southerly direction as pipe flow via 12" RCP culvert. Moderate flow was observed (±813'-835'). Point "F1" is the outlet of a 12" diameter RCP. Moderate flow observed. (±835'). From Point "F1" to Point "G1", runoff is conveyed in a southerly direction as channel flow via a 2' tall and 4' wide swale. Moderate flow was observed. (±835'-925'). Point "G1" is the inlet of a 12" diameter RCP. Moderate flow observed. (±925'). From Point "G1" to Point "H1", runoff is conveyed in a southerly direction as pipe flow via 12" diameter RCP culvert. Moderate flow was observed (±925'-968'). Point "H1" is the outlet of a 12" diameter RCP. Moderate flow observed. (±968'). From Point "H1" to Point "11 ", runoff is conveyed in a southerly direction as channel flow via a 2' tall and 4' wide swale. Moderate flow was observed (±968'-986'). Point "11" is the inlet of a 12" diameter RCP. Inlet was partially submerged. (±986'). From Point "11" to Point "J1", runoff is conveyed in an easterly direction as pipe flow via 12" diameter RCP culvert. Heavy flow was observed (±986'-1,022'). Point "J1" is the outlet of a 12" RCP. Outlet was fully submerged. (±1,022'). ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 30 Bethany Corner Renton, Washington From Point "J1" to Point "K1", runoff is conveyed in a southerly direction as channel flow via a 2' tall and 4' wide swale. Heavy flow was observed (±1,022'-1,037'). Point "K1" is the inlet of a 24" diameter Corrugated Metal Pipe (CMP) (±1,037'). From Point "K1" to Point "L 1", runoff is conveyed in a southerly direction as pipe flow via 24" CMP. Moderate flow was observed (±1,037'-1, 121'). Point "L 1", is a Type 1 CB with the outlet of a 24" diameter CMP pipe from the north and the inlet of a 12" CMP in a southeasterly direction. Facility ID No 180983. Standing water observed. (±1,121'). From Point "L1" to Point "M1", runoff is conveyed in a southeasterly direction as pipe flow via a 12" diameter CMP. Inlet was observed to be fully submerged. (±1, 121 '- 1, 180'). Point "M1" is the outlet of a 12" diameter CMP. Not observed. (±1, 180'). From Point "M1" to Point "N1", runoff is conveyed in a southeasterly direction as channel flow via Big Soos Creek. Moderate flow was observed. (±1,180'-1,599'). The downstream path crosses the Y. mile point during this stretch. Point "N1" is the inlet of an 18" diameter Corrugated Plastic Pipe (CPP) with a metal debris barrier. Moderate flow observed (±1,599'). From Point "N1" to Point "01", runoff is conveyed in a southerly direction under SE 168th Street via an 18" CPP. Moderate flow was observed (±1,599'-1,675'). Point "01" is the outlet of an 18" CPP discharging into Big Soos Creek. Moderate flow observed (±1,675'). The outlet could not be investigated in the field. This is the end of field investigation. DOWNSTREAM PATH 2 "A2" is a NDL for the Site. It is located in the southeastern corner of the Site. This NDL is the inlet of a 12" diameter reinforced concrete pipe conveying storm water in a southeasterly direction (±0). From Point "A2" to Point "B2", runoff continues in a southwesterly direction as pipe flow. No concentrated flow was observed (±0'-55'). Point "B2" is the outlet of a 12" reinforced concrete. (±55'). From Point "B2" to point "C2," runoff continues in a southwesterly direction as sheet flow. (±55'-85'). Point "C2" is Big Soos Creek which collects runoff and is the convergence point of Downstream Paths 1 and 2. (±85'). TASK 5: MITIGATION OF EXISTING OR POTENTIAL PROBLEMS A review of the King County Water and Land Resources Division -Drainage Services Section Documented Drainage Complaints within one mile of the downstream flow ©2016 D. R STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 31 Bethany Corner Renton, Washington paths revealed one complaint within the last ten years and has since been closed. Several drainage complaints exist within the downstream path but are not within the last ten years and are not applicable for Level One Downstream Analysis. The project should not create any problems as specified in Section 1.2.2.1 of the Manual and therefore is not required to provide Drainage Problem Impact Mitigation subject to the requirements of Section 1.2.2.2. A wetvault will provide flow control and basic water quality requirements for the entire Site. During construction, standard sediment and erosion control methods will be utilized. This will include the use of a stabilized construction entrance, perimeter silt fencing, and other necessary measures to minimize soil erosion during construction. ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 32 Bethany Corner Renton, Washington FIGURE 13 OFFSITE ANALYSIS DOWNSTREAM MAP ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Page 33 Bethany Corner Renton, Washington - - Al~ \ I , - A2_\ v:2- C2~V bi I Cl------....._ ~ "< "' ~ - I I I I I l u ~ u- SE 164TH STREET ~ I ~ ~ ~ ~ ' 1 VPROPOSEO DISCHARGE PA TH V /01-------......._ !:,: ~ ~ El--:;;; "< "' Fl -· -J HI v-JI I ' -/ 11 .____ Kl ~ ~ H- LI------~ Ml------ ~ MILE DOWNSTREAM POINT \ I ~~ \ ' 1 --------- , SE 168TH STREET 01---- NORTH GRAPHIC SCALE 0 100 200 400 1 INCH = 200 FT. _,,\ I I I \ R; \2016\0\16062\J\Drawings\Pfols\Figur~\1J-OOWNSTREMLl6062.dwg 12/15/2016 11:J9;,J.J AM POT COPYRIGH,:_© 2016, D.R. STRONG CONSULTING ENGINEERS INC. I IQ tll ~ ~ i ~; 1~~ I':~ ~ ' : ~ i I • Q<l ~,1 Cl.. ~ ~ i1i ~ I~ ~ ~ ~ 0 ~ ij !'.I) i m 0 ~ Cl 0:: rli !'.I) \g :s: ~ -0:: ,q:; :ii: ~ 8~:ac ..J >-'"" e ~ <:'"" :c: ~~a5 "' i!: ;i 0:: lJJ '"" !.JJ Ill oe !::: ~ ~ ~ ~ .. ('<') ..... LU ~ C!) ~ ORAFTFD SY.: C1W' OCSGNHJ BY: C)W' PRO.ECT ENGtNffR: 111,J DATE": ftu&N PRO.£CT NO.; t«1a FK;URC, 1:J I FIGURE 14 OFFSITE ANALYSIS DOWNSTREAM TABLE DOWNSTREAM PATH 1 Symbol Drainage Drainage Component Component Type, Description Name, and Size Type: sheet flow, swale, See map Stream, channel, pipe, drainage basin, vegetation, cover. Pond: Size: diameter depth, type of sensitive area, volume Surface area A1 Natural discharge area Runoff exits at the NOA along the western oropertv line of the Site. A1-B1 West sheet flow Sheet flow over till grass B1 Stream Big Soos Creek B1-C1 Southerly channel flow Big Soos Creek C1 Pipe inlet 12" diameter Reinforced Concrete Pipe (RCP) C1-D1 Easterly pipe flow 12~ diameter RCP. 01 Pipe outlet 12" diameter RCP D1-E1 Southerly channel flow 2' tall 3' wide swale E1 Pipe inlet 12" diameter RCP E1-F1 Southerly pipe flow 12" diameter RCP F1 Pipe outlet 12" diameter RCP F1-G1 Southerly channel flow 2' tall and 4' wide swale ©2016 D. R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Slope Distance Existing Potential From site Problems Problems Discharoe Constrictions, under capacity, ponding, % 1/4 mile= overtopping, flooding, habitat or 1,320 feet organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion ±0' None Observed None Anticipated None Observed None Anticipated ±45' None Observed None Anticipated None Observed None Anticipated ±502' None Observed None Anticipated ±807' None Observed None Anticipated None Observed None Anticipated ±813' None Observed None Anticipated None Observed None Anticipated ±835' None Observed None Anticipated None Observed None Anticipated Page 34 Observations of field inspector resource reviewer, or resident Tributary area, likelihood of problem, overflow pathways, potential impacts. No concentrated flow observed No concentrated flow observed Moderate flow observed Moderate flow observed Did not observe Moderate flow observed Moderate flow observed Moderate flow observed Moderate flow observed Moderate flow observed Moderate flow observed Moderate flow observed Bethany Corner Renton, Washington G1 G1-H1 H1 H1-11 11 11-J1 J1 J1-K1 K1 K1-L 1 L1 L1-M1 M1 M1-N1 N1 N1-01 01 Pipe inlet 12" diameter RCP Southerly pipe flow 12" diameter RCP Pipe outlet 12" diameter RCP Southerly channel flow 2' tall and 4' wide swale Pipe inlet 12" diameter RCP Easterly pipe flow 12" diameter RCP Pipe outlet 12" diameter RCP Southerly channel flow 2' tall 4' wide swale Pipe inlet 24" diameter Corrugated Metal Pipe /CMPl Southerly pipe flow 24" diameter CMP Type 1 CB Renton Facility No. 180983 Southeasterly pipe 12" diameter CMP Pipe outlet 12" diameter CMP Southeasterly channel Big Soos Creek flow Pipe inlet 18" diameter corrugated plastic pipe ICPP\ under SE 168'" Street Southerly pipe flow 18" diameter CPP Pipe outlet 18" diameterCPP. Discharging into Big Soos Creek ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis ±925' None Observed None Observed ±968' None Observed None Observed ±986' Partially submeraed None Observed ±1,022' Fully submerged None Observed ±1,037' None Observed None Observed ±1,121' None Observed Fully submerged ±1,180' None Observed None Observed ±1,599' None Observed None Observed ±1,675' None Observed Page 35 None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated None Anticipated - Moderate flow observed Moderate flow observed Moderate flow observed Moderate flow observed Heavy flow observed Heavy flow observed Heavy flow observed Heavily vegetated -moderate flow observed Moderate flow observed Moderate flow observed Standing water observed Heavy flow observed Moderate flow observed Moderate flow observed Moderate flow observed. Metal debris barrier coverinn inlet Moderate flow observed Discharge point not observed Bethany Corner Renton, Washington - DOWNSTREAM PATH 2 Symbol Drainage Drainage Component Component Type, Description Name, and Size Type: sheet flow, swale, See map Stream, channel, pipe, drainage basin, vegetation, cover, Pond; Size: diameter depth, type of sensitive area, volume Surface area A2 Natural discharge area -12" diameter RCP. Pioe inlet A2-B2 Southwesterly pipe flow 12" diameter RCP B2 Pipe outlet 12" diameter RCP B2-C2 Southwesterly sheet flow Sheet flow over moderately vegetated areas C2 Stream Big Soos Creek. Convergence point of Downstream Paths 1 and 2 ©2016 D.R. STRONG Consulting Engineers Inc. Level One Downstream Analysis Slope Distance Existing Potential From site Problems Problems Discharae Constrictions, under capacity, ponding, % 1/4 mile= overtopping, flooding, habitat or 1,320 feet organism destruction, scouring, bank sloughing, sedimentation, incision, other erosion ±0' None Observed None Anticipated None Observed None Anticipated ±55' None Observed None Anticipated None Observed None Anticipated ±85' Page 36 Observations of field inspector resource reviewer, or resident Tributary area, likelihood of problem, overflow pathways, potential impacts. No concentrated flow observed No concentrated flow observed No concentrated flow observed Moderate flow observed Did not observe Bethany Corner Renton, Washington SECTION IV FLOW CONTROL ANALYSIS AND WATER QUALITY DESIGN EXISTING SITE HYDROLOGY KCRTS was used to model runoff from the Site. The Site falls within the City's Flow Control Duration Standard -Matching Forested area. The Site was modeled as predeveloped forested condtions for target surfaces and impervious for flow-through surfaces (see Figure 15). Results of the KCRTS analysis are included in this section. Modeling Input for the Pre-developed Site I), Land Use Sumimry IArea----i I 9 I TIii forest! 1. 6 aaesl Tiil l'llsturc:I 0.00 acres 1 TIii Grass! 0.00 acres! Outwash Foresti D.00 acres Outwash Pasture! 0.00 aaes I o-.ahGraoa1 o.oa acres I Welland! 0.00 aaes I 0.05 acres Impervious! ' cTotal--~ [_ 2.00 acres Scale Factor : 1.00 Hourly Reduced Time SeriH: lpredov Compute Time Serles Modify User Input i ·Ale lor computed Time Serles (.TSF) Modeling Results Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac l~-1,~~ 11 1»1 I I . ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak (CFS) 0 .131 2 2/09/01 18:00 0.042 7 1/05/02 16:00 0.103 3 2/28/03 3:00 0.012 8 8/26/04 2:00 0.061 6 1/05/05 8:00 0.103 4 1/18/06 20:00 0.091 5 11/24/06 4:00 0.176 1 1/09/08 9:00 Computed Peaks ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report --Peaks Rank (CFS) 0.176 1 0.131 2 0.103 3 0.103 4 0.091 5 0.061 6 0.042 7 0.012 8 0.161 Page 37 Return Prob Period 100.00 25.00 10.00 5.00 3.00 2.00 1. 30 1.10 50.00 0.990 0. 960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 Bethany Corner Renton, Washington FIGURE 15 PREDEVELOPED AREA MAP ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 38 Bethany Corner Renton, Washington '·" ,,, \ h F (~-'.) ',t :~: \ -, ·c'i' ,; /\\f;; z:.n: I I I I I """ ,, I/ c1e-: :i~ I I I I I I I I I I I l: '·',i ' 1:_; 1;· r ti'· r:c,?1;, r: :?''-:ic ------ -1_:· J )',:--· ~-0_1· :--./,;,, 1-::c~J- '"t,_.'1;1' f I',, i l' t \ :,·· ·cs ....::f I ,, llJ I ::-J j!/;! I ,q; I ~i I-· ..... -, ~--, /. : .,r· ' ·; \ f) ') '' 1 .. /t········,,, " i -·,·, I I /t ,, I ·-·\;·-~ : I' LEGEND: WA ~-----1 ----------------- RS<Sa PROJECT AREA (FORESTED): 85,158 SI. (1.955 ACRES} FLOW-THROUGH AREA (IMPERVIOUS}: 2,036 SI, (0,047 ACRES) UNDISTURBED AREA (TRACT 8): 409 SF (0. 009 ACRES) @ NORTH GRAPHIC SCALE 0 20 40 60 1 INCH= 40 FT R: \2016\0\1606Z\.J\Drawings\Plofa\Figurt,s\1S-3PR[OEV_16062.dwg 12/2/2018 11:45:44 AM POT COPYRIGHT@ 2016, D.R. STRONG CONSULTING ENGINEERS INC. m ~ I ~~ I!' 5 ~g Ci <) ~ 0 ~ ~ [(l ~ ,q;: @ ~ Oj :::;: LIJ @ 8: le) -~ ::5 C!) ti: I! ~ 1 I'; i ~ Iii • ; ~ 0 a ~ ~ !l:: i\j ~$ ~ ,q; :<( 0 :t 3:: (.) ~ ;f :.. ,._ " :.: ,._ i: ~ 1;; ~ i,;; ~ ct llJ ,._ Cll "!I ~ DRAFTED BY: C')'lf' C£SICN£D BY: .J!ill PRO.ECT £NGINffR: 11N DATE: Hl&16 PRO.£CT NO.: IIOIZ """"" 15 I DEVELOPED SITE HYDROLOGY Soil Type The soil types are unchanged from predeveloped conditions. Land Cover KCRTS was used to model the developed peak runoff from the Site. The portions of the Site within the developable area tributary to the proposed detention facility were modeled as "Till Grass", and Impervious as appropriate. Results of the KCRTS analysis are included in this section. Modeling Input for RDIN Site Modeling Results $ land Use Summary r Area------"·--: 1111 Forest\ 0.00 acres] i I TIii Pasturer D.00 acres: 1111 Gras,:: I Outwash fDrest' Outwash Pasture! Outwaah GrHs Wetland 0.68 acres! ! 0.00 acres: ' D.BDaaesi O.DO acres D.80acrea' Impervious 1.17 acres· -·------- cTotol- i 1.15 acres: L ___ ' Scale Factor: 1.0D Hourly Redueed I ,o ·I 1·071 lnrerf Time Serles: r!rd~ln---------~I »I Compute Time Serles I Modify User Input I -Ale ia,-computed Time Serles [.TSF] Flow Frequency Analysis Time Series File:rdin.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.345 6 2/09/01 2:00 0.281 8 1/05/02 16:00 0.414 3 2/27/03 7:00 0.305 7 8/26/04 2:00 0.367 4 10/28/04 16:00 0.366 5 1/18/06 16:00 0.443 2 10/26/06 0:00 0.697 1 1/09/08 6:00 Computed Peaks ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report -----Flow Frequency Analysis------- --Peaks Rank Return Prob Page 39 (CFS) Period 0.697 1 100.00 0.990 0.443 2 25.00 0.960 0.414 3 0.367 4 0.366 5 0.345 6 0.305 7 0.281 8 0.612 10.00 0.900 5.00 0.800 3.00 0.667 2.00 0.500 1. 30 0.231 1.10 0.091 50.00 0.980 Bethany Corner Renton, Washington Modeling Input for the Bypass & Land u,. S..mm1ry TIii ForesrAr:~;;~:::1 TIii Pasture 0.00 1cre1I TIii Grass o.u •cre, 1 Outwash Forest 0.00 acrea 1 Outwash Pasture 0.00 acres! Outwash Grass 0.00 acres: I I Wetland• 0.00 acres; Impervious! 0.01 acres' ---------- cotal--·~ __ 0.15 •_creai Scale Fador: 1.00 Hourly Reduced Time Serlea: lbYPI Compute Time Serles Modify User Input I FIie for computed Time Serles [.TSF) Modeling Results Flow Frequency Analysis Time Series File:byp.tsf Project Location:Sea-Tac I =I·-, !J 1»1 I I ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak (CFS) 0.015 4 2/09/01 2:00 0.009 6 1/05/02 16:00 0.019 2 2/27/03 7:00 0.005 8 8/26/04 2:00 0.009 7 1/05/05 8:00 0.016 3 1/18/06 16:00 0.014 5 11/24/06 3:00 0.035 1 1/09/08 6:00 Computed Peaks ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report --Peaks Rank (CFS) 0.035 1 0.019 2 0.016 3 0.015 4 0.014 5 0.009 6 0.009 7 0.005 8 0.029 Page 40 Return Prob Period 100.00 0.990 25.00 0. 960 10.00 0.900 5.00 0.800 3.00 0.667 2.00 0.500 1. 30 0.231 1.10 0.091 50.00 0.980 Bethany Corner Renton, Washington FIGURE 16 DEVELOPED AREA MAP ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 41 Bethany Corner Renton, Washington "" I I I /1 I I I I I I I I I I I L, 1------------------- -t I~ !\! ::j Jg V''.L--r 1_ ~ AR£A BREAKDOWN -------- Ll ~ ~ ~ LJ ~ Ll D . ~ KCRTS INPUT VAULT BASIN fRmN/; IMPERVIOUS: TILL GRASS: BYPASS BASIN IB:,Pl; IMPERVIOUS: TILL GRASS: 70TAL SITE: AREA: TOTAL PROJECT AREA: 79,710 S.F. (1.BJO AC) 85,158 SF. (1.955 AC) VAULT TRIBUTARY AREAS; LOT AREA: IMPERVIOUS:• TILL GRASS: ROW AREA: IMPERVIOUS: TILL GRASS: TRACT A (SO): IMPERVIOUS: TILL GRASS: FLOW-1HROUGH AREA: IMPERVIOUS: TILL GRASS: 51,842 SF. (1.190 AC) 29,902 S.F. (0.686 AC) 21,940 SF. (0.504 AC) 21,JBJ SF. (0.491 AC) 19,650 SF. (0.451 AC) 1,7J4 SF. (0.040 AC) 7.347 S.F. (0.169 AC) 1,500 S.F. (0.035 AC) 5,847 S.F. (0.1J4 AC) 2,036 S.F. (0.047 AC) 2,036 S.F. (0.047 AC) 0 S.F (0.000 AC) BYPASS AREAS; LOT AREA: IMPERVIOUS: • TILL GRASS: ROW AREA: IMPERVIOUS: TILL GRASS: TRACT A (SO): IMPERVIOUS: TILL GRASS: 5,003 S.F. (O. 115 AC) 0 SF (0.000 AC) 5,003 S.F. (0. 115 AC) 655 S.F. (O. 015 AC) 590 S.F. (0.014 AC) 65 S.F (0.001 AC) 689 S.F. {0.016 AC) 0 SF. (0.000 AC) 689 S.F. (0.016 AC) UNQIS11/RBEQ AREAS; TRACT 8: 409 S.F. (0.009 AC) *ANALYSIS COMPLETED ASSUMING 10:Jr BMP CREDIT FOR ALL LOTS 50,896 S.F. (1.168 AC) 29,953 S.F. (0.688 AC) 590 S.F. (0.014 AC) 5,757 SF. (0.132 AC) @ NORTH GRAPHIC SCALE 0 20 40 60 1 INCH = 40 FT. R: \2016\0\16062\J'.\Dt-awing.s\Plots\Figuri,s\16-JDEY'. 16062.dwg 12/2/2016 11:49:05 AM POT COPYRIGHT @ 2016, D.R. STRONG CONSUL TING ENGINEERS INC. ., ~ ~ ili ~! ., .,~ 0: c:i ~ 0 I I • I ~ 0 I ~ 11 ! ~ ~ 0 ~ ij m ~ ~ I; 0 ~ ~ ~ ~ :"( ~ ~ lli ~ -q; ~ "( ~ @ 8E<: Cl ~::~ 0 ~ 1o Iii ~ ~iect ::s: o:i ~ LU ~ Cl ~ (0 ,._ ..... ~ ::j ~ l( DRAFTHJ BY; en, DESIGNED BY: CW PRO.ECT OIGINffR: Ill,,/ DATE:; rcuaJf' PRO.JCCT NO.: 1fJ1tlZ FTGURE; 16 I I I I I I I I I I I I I I I I I I I I PERFORMANCE STANDARDS The Site is required to adhere to Flow Control Duration Standard -Matching Forested site conditions of the existing site (reference 11-A of COR 2009 Surface Water Design Manual Amendment). A wet-vault will provide flow control and basic water quality treatment. The Project is required to "match the flow duration of pre-developed rates for forested (historic) site conditions over the range of flows extending from 50% of 2-year up to the full 50-year flow." (2009 Surface Water Design Manual Amendment, Sec. 1.2.3.1 ). ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 42 Bethany Corner Renton, Washington I I I I I I I I I I I I I I I I I I I FLOW CONTROL SYSTEM The Project will utilize an detention facility designed to control site runoff. The King County Runoff Time Series (KCRTS) software was used to size the facility. The detention pond design information is included in this section. Retention/Detention Facility Type of Facility: Facility Length: Facility Width: Facility Area: Effective Storage Depth: Stage O Elevation: Storage Volume: Riser Head: Riser Diameter: Number of orifices: Orifice# 1 2 Height (ft) 0.00 3.23 Detention Vault 96.00 ft 46. 00 ft 4416. sq. ft 5. 00 ft 0. 00 ft 22080. cu. ft 5.00 ft 12.00 inches 2 Diameter (in) 0.75 l. 38 Full Head Discharge (CFS) 0.034 0.068 Top Notch Weir: None Outflow Rating Curve: None Pipe Diameter (in) 4.0 Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 0.00 0. 0.000 0.000 0.00 0.01 0.01 44. 0.001 0.001 0.00 0.02 0.02 88. 0.002 0.002 0.00 0.03 0.03 133. 0.003 0.003 0.00 0.04 0.04 177. 0.004 0.003 0.00 0.05 0.05 221. 0.005 0.004 0.00 0.06 0.06 265. 0.006 0.004 0.00 0.16 0.16 707. 0.016 0.006 0.00 0 .26 0.26 1148. 0.026 0.008 0.00 0.36 0.36 1590. 0.036 0.009 0.00 0. 4 6 0.46 2031. 0.047 0.010 0.00 0. 56 0.56 2473. 0.057 0. 011 0.00 0.66 0.66 2 915. 0.067 0.012 0.00 0.76 0.76 3356. 0.077 0.013 0.00 0.86 0.86 3798. 0.087 0.014 0.00 0. 96 0. 96 4239. 0.097 0.015 0.00 l. 06 l. 06 4681. 0.107 0.016 0.00 1.16 1.16 5123. 0 .118 0.016 0.00 l. 26 l. 26 5564. 0.128 0.017 0.00 l. 36 l. 36 6006. 0 .138 0.018 0.00 l. 46 l. 46 6447. 0.148 0.018 0.00 l. 56 l. 56 6889. 0.158 0.019 0.00 ©2016 D.R. STRONG Consulting Engineers Inc. Page 43 Bethany Corner Technical Information Report Renton, Washington I I 1. 66 1. 66 7331. 0.168 0.020 0.00 I 1. 76 1. 76 7772. 0 .178 0.020 0.00 1. 86 1. 86 8214. 0.189 0.021 0.00 1. 96 1. 96 8655. 0.199 0. 021 0.00 2.06 2.06 9097. 0.209 0.022 0.00 I 2.16 2.16 9539. 0.219 0.022 0.00 2.26 2.26 9980. 0.229 0.023 0.00 2.36 2.36 10422. 0.239 0.023 0.00 I 2.46 2.46 10863. 0.249 0.024 0.00 2.56 2.56 11305. 0.260 0.024 0.00 2.66 2.66 11747. 0.270 0.025 0.00 I 2.76 2.76 12188. 0.280 0.025 0.00 2.86 2.86 12630. 0.290 0.026 0.00 2. 96 2. 96 13071. 0.300 0.026 0.00 3.06 3.06 13513. 0.310 0. 027 0.00 I 3.16 3.16 13955. 0.320 0.027 0.00 3.23 3.23 14264. 0.327 0.027 0.00 3.24 3.24 14308. 0.328 0.028 0.00 I 3 .26 3.26 14396. 0.330 0.029 0.00 3.27 3.27 14440. 0.332 0.031 0.00 3.29 3.29 14529. 0.334 0.034 0.00 3.30 3.30 14573. 0.335 0.037 0.00 I 3.32 3.32 14 661. 0.337 0.042 0.00 3.33 3.33 14705. 0.338 0.044 0.00 3.34 3.34 14749. 0.339 0.045 0.00 I 3.44 3.44 15191. 0.349 0.052 0.00 3.54 3.54 15633. 0.359 0.057 0.00 3.64 3.64 16074. 0.369 0.062 0.00 3.74 3.74 16516. 0.379 0.066 0.00 I 3.84 3.84 16957. 0.389 0.070 0.00 3.94 3.94 17399. 0.399 0.074 0.00 4.04 4.04 17841. 0. 410 0. 077 0.00 I 4.14 4.14 18282. 0. 420 0.080 0.00 4.24 4.24 18724. 0.430 0.083 0.00 4.34 4.34 19165. 0.440 0.086 0.00 I 4.44 4.44 19607. 0.450 0.089 0.00 4.54 4.54 20049. 0.460 0.091 0.00 4.64 4.64 20490. 0.470 0.094 0.00 4.74 4.74 20932. 0.481 0. 096 0.00 I 4.84 4.84 21373. 0.491 0.099 0.00 4.94 4.94 21815. 0.501 0 .101 0.00 5.00 5.00 22080. 0.507 0.102 0.00 I 5 .10 5.10 22522. 0.517 0.413 0.00 5.20 5.20 22963. 0.527 0.978 0.00 5.30 5.30 23405. 0.537 1. 710 0.00 5. 4 0 5.40 23846. 0.547 2.500 0.00 I 5.50 5.50 24288. 0.558 2. 790 0.00 5.60 5.60 24730. 0. 568 3.040 0.00 5. 70 5.70 25171. 0.578 3.280 0.00 I 5. 80 5.80 25613. 0.588 3.500 0.00 5.90 5.90 26054. 0.598 3.710 0.00 6.00 6.00 26496. 0.608 3.900 0.00 I 6.10 6.10 26938. 0.618 4.090 0.00 6 .20 6.20 27379. 0.629 4.270 0.00 I ©2016 D. R. STRONG Consulting Engineers Inc. Page 44 Bethany Corner Technical Information Report Renton, Washington I I I I I I I I I I I I I I I I I I I 6.30 6.30 27821. 0.639 4.440 0.00 6.40 6. 40 28262. 0.649 4.600 0.00 6.50 6.50 28704. 0.659 4.760 0.00 6.60 6.60 29146. 0.669 4.920 0.00 6. 70 6.70 29587. 0.679 5.070 0.00 6.80 6. 80 30029. 0.689 5.210 0.00 6.90 6.90 30470. 0.700 5.350 0.00 7.00 7.00 30912. 0.710 5.490 0.00 Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) l 0.70 0.45 5 .11 5 .11 22547. 0.518 2 0.34 0.12 5.01 5.01 22113. 3 0.44 0.09 4.35 4.35 19193. 4 0.41 0.08 4.30 4.30 19003. 5 0.37 0.06 3.60 3.60 15883. 6 0.37 0.03 3.14 3.14 13862. 7 0.28 0.03 2.79 2.79 12313. 8 0.30 0.02 1. 95 1. 95 8624. Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow 1 0.45 0.03 ******** 2 0.12 0.02 ******** 3 0.09 0.01 ******** 4 0.08 0.02 ******** 5 0.06 0.02 ******** 6 0.03 0.01 ******** 7 0.03 0.01 ******** 8 0.02 0.01 ******** ---------------------------------- Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: Peak Outflow Discharge: Peak Reservoir Stage: Peak Reservoir Elev: 0.697 0.445 5 .11 5 .11 CFS CFS Ft Ft Target ******* 0.13 ******* ******* ******* ******* ******* ******* at 6:00 at 10:00 Peak Reservoir Storage: 22547. Cu-Ft 0.518 Ac-Ft Add Time Series:byp.tsf Cale 0. 46 0.14 0.09 0.09 0.07 0.03 0.03 0.02 on Jan on Jan 0.508 0.441 0.436 0.365 0.318 0.283 0.198 9 in 9 in Year 8 Year 8 Peak Summed Discharge: 0.456 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report -----Flow Frequency Analysis------- --Peaks --Rank Return Prob Page 45 Bethany Corner Renton, Washington (CFS) (CFS) (ft) Period 0.125 2 2/09/01 20:00 0.445 5 .11 1 100.00 0.990 0.025 7 1/07/02 4:00 0.125 5.01 2 25.00 0. 960 0.085 4 3/06/03 22:00 0.086 4.35 3 10.00 0.900 0.021 8 8/26/04 7:00 0.085 4.30 4 5.00 0.800 0.027 6 1/08/05 5:00 0.060 3.60 5 3.00 0.667 0.060 5 1/19/06 0:00 0.027 3.14 6 2.00 0.500 0.086 3 11/24/06 8:00 0.025 2.79 7 1. 30 0.231 0.445 1 1/09/08 10:00 0.021 1. 95 8 1.10 0.091 Computed Peaks 0.338 5.08 50.00 0.980 Flow Frequency Analysis Time Series File:dsout.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 0.135 2 2/09/01 20:00 0.456 1 100.00 0.990 0.030 7 1/05/02 16:00 0 .135 2 25.00 0. 960 0.092 4 3/06/03 21:00 0.095 3 10.00 0.900 0.024 8 8/26/04 2:00 0.092 4 5.00 0.800 0.032 6 1/05/05 8:00 0.068 5 3.00 0.667 0.068 5 1/19/06 0:00 0.032 6 2.00 0.500 0.095 3 11/24/06 7:00 0.030 7 1. 30 0.231 0.456 1 1/09/08 10:00 0.024 8 1.10 0.091 Computed Peaks 0.349 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS % % % 0.002 31735 51. 7 53 51. 7 53 48.247 0.482E+OO 0.005 6972 11.370 63.123 36.877 0.369E+OO 0.009 6435 10.494 73.617 2 6. 38 3 0. 2 64E+00 0.012 6038 9.847 83. 4 64 16.536 0.165E+OO 0.016 3952 6.445 89.909 10.091 0.101E+OO 0.019 2518 4.106 94.015 5.985 0.598E-01 0.023 1795 2.927 96. 942 3.058 0.306E-01 0.026 1321 2.154 99.097 0.903 0.903E-02 0.030 257 0.419 99.516 0.484 0.484E-02 0.033 19 0.031 99.547 0.453 0.453E-02 0.037 14 0.023 99. 5 69 0.431 0. 431E-02 0.040 11 0.018 99.587 0.413 0. 413E-02 0.044 12 0.020 99.607 0.393 0.393E-02 0.047 22 0.036 99.643 0.357 0.357E-02 0.051 24 0.039 99.682 0.318 0.318E-02 0.054 26 0.042 99.724 0.276 0.276E-02 0.058 23 0.038 99. 7 62 0.238 0.238E-02 0.061 25 0.041 99. 8 03 0.197 0.197E-02 0.065 14 0.023 99.826 0.174 0.174E-02 0.068 10 0.016 99.842 0.158 0.158E-02 0.072 13 0. 021 99.863 0 .137 0.137E-02 0.075 12 0.020 99.883 0 .117 0.117E-02 0.079 10 0.016 99.899 0.101 O.lOlE-02 0.082 12 0.020 99.918 0.082 0.815E-03 ©2016 D. R. STRONG Consulting Engineers Inc. Page 46 Bethany Corner Technical Information Report Renton, Washington Period (CFS) 0.125 0.025 0.085 0.021 0.027 0.060 0.086 0.445 2 7 4 8 6 5 3 1 2/09/01 1/07/02 3/06/03 8/26/04 1/08/05 1/19/06 20:00 4:00 22:00 7:00 5:00 0:00 8:00 (CFS) 0.445 0.125 0.086 0.085 0.060 0. 027 0.025 0.021 0.338 (ft) 5 .11 5.01 4.35 4.30 3.60 3.14 2.79 1. 95 5.08 1 100.00 0.990 2 25.00 0.960 3 10.00 0.900 4 5.00 0.800 5 3.00 0.667 6 2.00 0.500 11/24/06 1/09/08 7 1.30 0.231 10:00 8 1.10 0.091 Computed Peaks Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac 50.00 0.980 ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate (CFS) 0.135 0.030 0.092 0.024 0.032 0.068 0.095 0.456 Rank Time of Peak --Peaks Rank Return Prob (CFS) Period 2 2/09/01 20:00 7 1/05/02 16:00 4 3/06/03 21:00 8 8/26/04 2:00 6 1/05/05 8:00 5 1/19/06 0:00 3 11/24/06 7:00 1 1/09/08 10:00 0.456 1 100.00 0.990 Computed Peaks 0 .135 0.095 0.092 0. 068 0.032 0.030 0.024 0.349 Flow Duration from Time Series File:rdout.tsf 2 3 4 5 6 7 8 25.00 10.00 5.00 3.00 2.00 1. 30 1.10 50.00 Cutoff Count Frequency CDF Exceedence Probability CFS % % % 0.002 31735 51.753 51.753 48.247 0.482E+OO 0.005 6972 11.370 63.123 36.877 0.369E+OO 0.009 6435 10.494 73.617 26.383 0.264E+OO 0.012 6038 9.847 83.464 16.536 0.165E+00 0.016 3952 6.445 89.909 10.091 0.101E+OO 0.019 2518 4.106 94.015 5.985 0.598E-01 0.023 1795 2.927 96.942 3.058 0.306E-01 0.026 1321 2.154 99.097 0.903 0.903E-02 0.030 257 0.419 99.516 0.484 0.484E-02 0.033 19 0.031 99.547 0.453 0.453E-02 0.037 14 0.023 99.569 0.431 0.431E-02 0.040 11 0.018 99.587 0.413 0.413E-02 0.044 12 0.020 99.607 0.393 0.393E-02 0.047 22 0.036 99.643 0.357 0.357E-02 0.051 24 0.039 99.682 0.318 0.318E-02 0.054 0.058 0.061 0.065 0.068 0.072 0.075 0.079 0.082 26 23 25 14 10 13 12 10 12 0.042 0.038 0.041 0.023 0.016 0.021 0.020 0.016 0.020 ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report 99.724 99. 7 62 99.803 99.826 99.842 99. 8 63 99.883 99.899 99. 918 0.276 0.238 0.197 0 .174 0.158 0.137 0.117 0.101 0.082 Page 46 0.276E-02 0.238E-02 0.197E-02 0.174E-02 0.158E-02 0.137E-02 0.117E-02 O.lOlE-02 0.815E-03 0. 960 0.900 0.800 0.667 0.500 0.231 0.091 0.980 Bethany Corner Renton, Washington I I 0.086 16 0.026 99.945 0.055 0.554E-03 0.089 12 0.020 99. 964 0.036 0.359E-03 I 0.093 7 0. 011 99.976 0.024 0.245E-03 0. 096 4 0.007 99.982 0.018 0.179E-03 0.100 5 0.008 99.990 0.010 0.978E-04 I 0.103 5 0.008 99.998 0.002 0.163E-04 0.107 0 0.000 99.998 0.002 0.163E-04 0 .110 0 0.000 99.998 0.002 0.163E-04 I 0 .114 0 0.000 99.998 0.002 0.163E-04 0 .117 0 0.000 99.998 0.002 0.163E-04 0.121 0 0.000 99.998 0.002 0.163E-04 0.124 0 0.000 99.998 0.002 C.163E-04 I Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence Probability I CFS % % % 0.002 31731 51.747 51.747 48.253 0.483E+00 0.006 7398 12.065 63. 811 36.189 0.362E+OO 0.009 6714 10.949 7 4. 7 60 25.240 0.252E+00 I 0. 013 5830 9.508 84.268 15.732 0.157E+OO 0.017 4128 6.732 91.000 9.000 0.900E-01 0.021 2134 3.480 94.480 5.520 0.552E-01 I 0.025 1584 2.583 97.063 2.937 0.294E-01 0.028 1048 1.709 98. 772 1.228 0.123E-01 0.032 425 0.693 99.465 0.535 0.535E-02 I 0.036 39 0. 064 99.529 0. 471 0. 4 71E-02 0.040 20 0.033 99.561 0.439 0.439E-02 0.043 16 0.026 99.587 0.413 0.413E-02 0.047 14 0.023 99.610 0.390 0.390E-02 I 0.051 20 0.033 99.643 0.357 0.357E-02 0.055 23 0.038 99.680 0.320 0.320E-02 0.059 26 0.042 99.723 0. 277 0.277E-02 I 0.062 15 0.024 99.747 0.253 0.253E-02 0.066 26 0.042 99.790 0.210 0.210E-02 0.070 23 0.038 99.827 0.173 0.173E-02 0.074 9 0.015 99.842 0.158 0.158E-02 I 0.078 12 0.020 99.861 0.139 0 .139E-02 0.081 12 0.020 99.881 0.119 0.119E-02 0.085 9 0.015 99.896 0.104 0.104E-02 I 0.089 11 0.018 99.914 0.086 0.864E-03 0.093 19 0.031 99.945 0.055 0.554E-03 0. 096 14 0.023 99.967 0.033 0.326E-03 0.100 3 0.005 99. 972 0.028 0.277E-03 I 0.104 4 0.007 99.979 0.021 0.212E-03 0.108 4 0.007 99.985 0.015 0.147E-03 0 .112 5 0.008 99.993 0.007 0.652E-04 I 0.115 3 0.005 99.998 0.002 0.163E-04 0 .119 0 0.000 99.998 0.002 0.163E-04 0.123 0 0.000 99.998 0.002 0.163E-04 I 0.127 0 0.000 99.998 0.002 0.163E-04 0 .130 0 0.000 99.998 0.002 0.163E-04 0 .134 0 0.000 99.998 0.002 0.163E-04 Duration Comparison Anaylsis I Base File: predev.tsf I ~2016 D.R. STRONG Consulting Engineers Inc. Page 47 Bethany Comer Technical Information Report Renton, Washington New File: dsout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time--------------Check of Cutoff Base New %Change Probability 0.030 0.85E-02 0.65E-02 -23.1 I 0.85E-02 0.038 0.59E-02 0.45E-02 -24.0 I 0.59E-02 0.046 0.47E-02 0.40E-02 -14.7 I 0.47E-02 0.053 0.34E-02 0.34E-02 -2.4 I 0.34E-02 0.061 0.26E-02 0.26E-02 0.0 I 0.26E-02 0.069 0.20E-02 0.18E-02 -7.4 I 0.20E-02 0.076 0 .13E-02 0.14E-02 10.0 I 0 .13E-02 0.084 0.95E-03 0.11E-02 13. 8 I 0.95E-03 0.092 0.57E-03 0.65E-03 14.3 I 0.57E-03 0.100 0.34E-03 0.29E-03 -14.3 I 0.34E-03 0.107 0.18E-03 0.15E-03 -18.2 I O.lSE-03 0.115 0 .13E-03 0.16E-04 -87.5 I 0. 13E-03 0.123 0.82E-04 0.16E-04 -80.0 I 0.82E-04 0.130 0.16E-04 0.16E-04 0.0 I 0.16E-04 Maximum positive excursion= 0.005 cfs ( 5.7%) occurring at 0.080 cfs on the Base Data:predev.tsf and at 0.085 cfs on the New Data:dsout.tsf Maximum negative excursion= 0.010 cfs (-21.7%) occurring at 0.044 cfs on the Base Data:predev.tsf and at 0.035 cfs on the New Data:dsout.tsf ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Page 48 Base 0.030 0.038 0.046 0.053 0. 061 0.069 0.076 0.084 0.092 0.100 0.107 0.115 0.123 0.130 Tolerance------- New %Change 0.029 -3.3 0.031 -18.7 0.036 -20.8 0.053 -1. 4 0. 061 0.0 0. 067 -2.2 0.079 3.6 0.087 3.7 0.093 0.7 0. 096 -3.4 0.106 -0.9 0.108 -5.6 0 .111 -9.4 0 .135 3.7 Bethany Corner Renton, Washington Flow Frequency Return Period 2 5 10 20 50 100 10"'~----------------------------'=-~--------:...., ____ _.:_~---"'"------'-'~----'~ r.'.Gu1 ~~; ,n See-T~c • iii ~ s e' 10·1'+------------------------------"'------------~------------- £ ~ 0 10 '-'----------------------------------------------~ 1Q 20 30 Duration Analysis ~ 1--------------- 0 •.. ~ 0 ~- ~ R 0 " 0 " 0 0 50 Cumuliruve PrntJab1hty ", .,,. ' .. 60 70 90 95 98 99 T:CL,l dsout ur + '\,~"-- , ~--------------------- ; 0 °'}\, ">-\'~ +------------------------------~~- 00 ~ g ol-' 10 -0 ,o ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report 10 -J \,. ~~:..,;_ ----- -·--= ~-: 10 ·2 Prab,1rn11ty Exceedence Page 49 ' ' '. 10 " ' 10' Bethany Corner Renton, Washington WATER QUALITY TREATMENT SYSTEM The Project is required to adhere to the City of Renton's Basic Water Quality treatment criteria. A combined detention/water quality vault located within Tract A is proposed to accommodate this requirement. Sizing for a wetvault was calculated from the formula provided by Section 6.4.1. 1 Methods of Analysis of the Manual. The minimum wetpool volume required is 6,262 cubic feet. The Project will provide 11,333 cubic feet of dead storage. The wetvault will occupy the eastern half of the detention vault. The vault geometry provides a length to width ratio of 4.33 : 1 so a removable baffle will be provided as shown on the plans. BASIC WETVAUL T ANALYSIS As required per Section 6.4.1.1 2009 King County Step 1: Identify required water quality facility volume factor C'f') f= 3 (basic wetpond volume factor) Step 2: Determine rainfall (R) for the mean annual storm per Fig. 6.4.1.A R= 0.47 in. Step 3: Calculate runoff from the mean annual storm (Vr) for the developed site. V, = (0.9A, + 0.25A,9 + 0.10A" + 0.01A,) x R/12 Vr = volume of runoff from mean annual storm (c.f.) A,= area of impervious surface (s.f.) A,,= area of till soil covered with grass (s.f.) A11= area of till soil covered with till forest (s.f.) A,= area of outwash soil covered with grass or forest (s.f.) R= rainfall from mean annual storm (in.) Ai= 50,896 s.f. Atg= 29,953 s.f. A,,= s.f. Ao= 0 s.f. R= 0.47 in. Vr:: 2,087 c.f. Step 4: Calculate water quality volume (Vb). Vb;:;. f x Vr where . V,= water quality volume (cf) f= volume factor from Step 1 Vr = runoff volume from Step 3 V,= 6,262 c.f. (minimum wetpool volume required) ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Page 50 where . Bethany Corner Renton. Washington FIGURE 17 DETENTION & WATER QUALITY FACILITY DETAILS ©2016 D. R. STRONG Consulting Engineers Inc. Technical lnfonnation Report Page 51 Bethany Corner Renton, Washington l • ~ • l i I i t I • I w i ~ 6 ~ ~ X X X X I X X X L a:: u.J z a:: 0 u >-z <( ~ u.J [Il eov .,.,1.00 • POm£TER --,_ _____ .,,.. \., IINflCD) 'l:WA.N'" lln'H LOQl!IM; 8t(. 7S -(nP.) ~ rAtf-"~K.-nm-. I, k __ /Jt,: ,I BOi.-4t44J'I- 8 ~ ' ' ~ ~ 121.NET 8 j -~ " ~~ ii \ II I " I ~ I' ) fl--ri. "" l (7'tP. I ' ' i ( I ~ ., ' /IOIOVAa£ 8AIFI..£ ll&Ct.L ~12.!B IBOV 412. 7::i • PfRIIICTER (LO!f!lll' CEJ..L) ~11.88 /8011-416..'3 t,--..... JIJ• s«JN£ ACCE3S HAreH ~ ,.,, ""''""" ,,. ounc, B II B L L " L J--22.sr--f--22."r---i LA @ NORTH VAULT DETAIL ,·-20 ~1R(JI.. Ra) ~ BENT AS RE'QD Fat ""'"'-" .,,._,,,""" °"""\ I -rs?&'t I f ........ , __ :-1 .......... --- [ ,f• El.BOW r2" CNP '= +_... = , •1.E I • .,. I «1EH1ION DEP'fH -'"'"'"''' l (SEE~ of) [ f- ' """' . .,,....,,,£::~""-------'--~ ~:==1·, r~· ···~~- --a.7.5·12i::. r ~ (SHNIP EZIG£D SHa> MUB)r r ,,,..u...._ fflOP DETAIL F"ROP NOTES: 1. ounn c.¥'Aall:' iao-m P£AK 11.0W 2. IICTAL !'MTS: ~ RCSISTNIT. ~~ PA/fTS ~ &t.LVN.fznt F'PE l'Alt'TS TD HAW: ASl'HAJ.T 1REA111ENT f. J; IF U!'TAL Cl.ln£1' F'IPf: CCNEC1S ID CDIOlr ca«:ltC7C PFt:: am.er PF'C 7tl HIIIC SIII001H Q.D. a:AJN.. 7tl ~~J.D.I..ESS1/4" 4. PROWDE AT J.£AST O#E 3ilr»O GNJ&£ SVPP<Rr BR,IQ(CT ANCHaED ro CONa£TF 1MU. ~ J" """"'-SPAON<) ~ LOCA1l" fUIOW ~) AS N£C£SSM'r 7tl l'WO~ IIINOltAI a.£AltNI(% AS SHOIIN. --fls.o.Ml!Ei;'lt.t. NE 1/4 S£Cn0N 29, TOWNSHIP 23 N, RANG£ 5 £, W.M. BETHANY CORNER IIARlt£1J "DRAIN" #l1H LoaaNG Ba.1S (n,P.) "ARl(£JJ "DRAIN" Vtl1H I..JJCl(JNG Ba.15 (T'IP.) RJM a, .. "2&00 5',rl{)" ~ UIXJER .I, .JIJ. SOUN£~ HIN«D ACC£SS HArr:H / FRAME ANO 24• ROIJND SICIUD COlo!Ji' FRAM£ ANO a-4,• RIXN) sa.XJ OOioP \ -"''·"" / """"' """' "" .,,_,,, /77 ,,,.,...1-_-~flL-, -~-. -------:-.::;~; I! Ii _J[ .4---J __ r ----. __ ____ __ l ~ ! ·--·--- '.:.___...L..-----jl,-, I ! ,y """'""' -,-., ' I .,..,_ • f---.._ n.J I I ] 8 I -....._~~ t: i: ~ ---·-(nP) -' Jl5 418..50 ..---I---' a•rc..!!MET!.<[J<E"'"'"'"""'"--'"'-.J....._ a 12" HIT E-.Ul!.50 l j1E; ••• ! i I """"'g.~------------; ~ / I I ~ I i so1m11 ,ts.SD ; ,r camK1 51RUc:rrJRE --y I , ~ t___.,.. 9" ~ ,r oonET E•41&!11J ! ! !.-_s------..:.... AP a.a, ~-' _ .. -1· L, =========--== ===, --_ _.-.--~ l.fJ'A~~ SEDNENr Sn:RAGE {T'fP,) SEC710N A-~ ,• .. 15 F1W1C AND 24• RQJHD SGUJ CO'iE'!' .::i'iiru' Gl'M'IE" w/ uaJER .1, JtJ" .sl:IVM'f" MAR1tED TJRAJN" 111H Lot:Ja«J IKUS (T'IP.) Loa<NI.E f#laD ACCESS HATCH n 427.00 """ a-'211.00 -"""' TOP OF' VAILT J I I ~ f:Xl51WG G1'ADE ~-------,'=~ i 1· ~--_-... -.. -,.,.--:: J i+! --_..L..-+1i~ ~~ ~SD·~ ti ; ~ /Li! :_ . ~ . ~ i I ' ~ ,,. """"' """'""' _/ rf'JLI ~ :::~ _ _ I -1LD ,,. amu C•''""' --.cs---t:= _ ----d I _ ...... "' -a ,, ... ,"'_,,..,LJtt=, ,,.,me-, .... ·-~ ,,,,.,., """'"' '""·' 11 ~ I I r' '"--'= c": ---'t --L~ r.o' A\oE'rJ\GE" SEDWEHT S7CRAGIE" (Trf'.) SEC110N 8-8 ·- NOTe: DE1ENTIQN SWMMY SHE£T T2-, FR<P \ ROIOVA&E IIMIEl'11QlfT !(JS/!1r \ OXPtJNt: (JR Fl.MG£ Ill i llflf@.'1~41191,awi ~.---,-;. Sli"ARA1F '!iiTRCJC1V1W.. f1CSIGH Pl.ANS MID wU.Q.IA11Q'IIS rotJt THC PtfCIP05DJ S1tll'III VM.11.T l«IST 8£ $U!U71!ll' TO THC l!AJI.DNG 0€PNt'TWJJT.. A SlPARA1F tllJUJING P£/IJIIT APFUCHKJN a.L 8£ R£QIWIEIJ FOR 1HE CONS1RUCT/at rT 71£ VAIL T. VAU!. T NOTES: I. ACCESS OP£NINGS 9W.L BE POS110NED A .w..ut OF !llJ n FROM IINY J.LIC4 ~ #ITHM '1HE VAULT. AND AT 11£ M£T .N«J OUnET. 2. IBOV • INSIDE BOT7Urt OF VAILT aEVAlltW. .,: VMlt. T QM 1F ro /Na.lJDC r~· HATCH DE5CNEEJ FOR £ASY Ol'OIING. ~~ PU 1F IIE.DED n, ElSOII' wrH tJR/FIC£ AS SP£t:JFEIJ £1..BOW RESTRICTOR DETAIL - RECOMMENDED FORAPPOVAL BY: Date· __ _ BY· Date __ _ BY: Date: __ _ N,S BY. Date __ _ .tl -c::.11 a wi:irt:tio Dlil'9 B1tDreo Tou DIii ._.._!11.__"""' CD.MT,IQOI\WN F;.,J,f·~·' ""·,1{~ ~ ~ ~'~1 ~~ -./ *~ct""'~ {,~ l'(ONAL '?!7" """'la -i.. -... -.. BY I DATE I .APPR I -.. @BID) D.R. STRONG :::::J=:=s o .... .-l'-..0.MO __. ..... CITY OF 15 NOIED :" * RENTON I.·:-=-I Plonnlng/Bulldfng/PubHc woru Dept. -- BElHANY CORNER VAULT PLAN AND DETAILS 164JJ & 1&451 111TH A',DjUE SE RENTON, WASHINGTON 98056 11.21.11 ·-014 NO. REVISION 4 ... ,. ,, DRS PRCl.ECT NO. 16062 IAI-ININN~ IAIA SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per Core Requirement #4 of the KCSWDM, the conveyance system must be analyzed and designed for the existing tributary and developed onsite runoff. Pipe systems shall be designed to convey the 25-year storm with a minimum of 6-inches of freeboard between the design water surface and structure grate. Any overflow from the 1 DO-year design storm must not create or aggravate a severe flooding problem. The Rational Method will be used to calculate the Q-Ratio for each pipe node. A conveyance system consisting primarily of pipes and catch basins will be designed for the Project. Onsite runoff will be collected by the multiple catch basins. Pipes are typically six-inch to twelve-inch diameter LCPE material. Per Figures 3.2.1.C and 3.2.1.D in the 2009 Manual the 24-hour precipitation in inches is 3.4 and 3.9 for the 25-year and 1 DO-year storms respectively. In all cases the 25-year storm was conveyed with at least 6-inches of freeboard. There were no overflows as a result of the 1 OD-year storm. ©2016 0. R. STRONG Consulting Engineers Inc. Technical Information Report Page 52 Bethany Corner Renton, Washington FIGCRE 3.:.1.C 15-YE..\R 14-HOUR ISOPIXYJ.-\LS "' .,. ., ,,, . WESTERN KING COUNTY 25-Year 24-Hour Precipitation in Inches " I ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report ._. .,. .l-16 Page 53 -··c·,.,..~ .... u ~,,.,.. ,:<,<, .. 1T t,!> Bethany Corner Renton, Washington 3.1.l F.ATIONAI.METIIOD IIGl1U: 3.2.1.D 100-YI...\R 2-1-HOFR ISOPLl'YlALS WESTERN KING COUNTY 100-Year 24-Hour Precipitation in Inches 2009 Surlace w-0.-..,n M"""'1 D ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report ~ * 2 'r·-· ~ {§·~ ,, \ ~\·· ..,{f "·--\ ;.....I, D JJ' .... \.~ ~-'\,' ~-... ~--,,.. ,,.. ' ~'? <:, ,. .... <,· 3--17 Page 54 -~ ¢, -,; ~/'-· ~·-~~Lc • .,f ..... .,'? 1''9-'!009 Bethany Corner Renton, Washington BACKWATER ANALYSIS ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 55 Bethany Corner Renton, Washington Pipe P-8 Path R \201610\ 1606213\Documents\A.nalysis\KC BVV\ 161212\8ACKWATER"16062_25 xis Storm Water Runoff Variables: A= Total of Subasin ar1d Tributary Areas C= Runoff Coefficient (the anticipated proportion of rainfall volume that runs off the area) see ·09 KCSWM Table 3 2 1A Cc= Composite Runoff Coefficient Cc= S{C,,'An)IAT-Ol•I T 0= Time of ConcentraLion (Typically 6.3 minutes which is the minimum value used 111 calculations) R= design return fre.9.uenc· iR"' Unil peak rainfall 1nlensity fac1or iR= (aR)(TclA(-bRl aR.bR= coefficients from '09 KCSWM Table 3.2.1 Bused to adjust the equa1ion for the design storm IR= Peak rainfall intensity factor for a storm of return frequency 'R' I~= P~'1, P 11:e total precipitation (inches) for the 24-hour storm event for the given frequency See lssopluvial Maps 111 '09 KCSWM Figures 3 2 1.0 Q~= peak flow (cfs) for a storm of return frequency 'R' o~= c~·i~'A The Q-Raho descnbes lhe ralio of the tributary flow to the main upstream flow. Ra 25 -year s1orm 8R"' 266 bR"' 065 PR"' 3.4 inches Conveyance System Variables: d= pipe diameter 11"' Manning's Number I= length of pipe Structures Subasins & Tributanes FROM CB ToCB 8 7 8 A A C c, T< ,, Ac Ac Mm CB-8 TO INLET 2 10226 0.23 0.58 63 '" '" Os SOs Q. d Material subas1n Ralio ci, els '" 0.60 2 73 0 37 0.37 000 12 N-12 FROM RUN 9-7 1957 0.04 0.90 I P-7 7 INLET 2 7 794 0.02 0.90 P-7 7 INLET 2 7 2751 0.06 0.90 63 0.80 2 73 0. 16 0.53 0.30 12 N-12 12977 0.30 0.64 CB-6 TO INLET 1 P-6 6 5 6 30608 0.70 0.59 63 080 273 1.14 1.14 0.00 f2 N-12 P-5 5 4 5 28631 066 0.59 63 080 273 1 05 2.19 0.48 12 N-12 P-4 4 INLET 1 4 785 0 02 0.90 63 080 273 004 2.23 0.02 12 N-12 60024 1.38 0.59 CB-11 TO CB-1 P-12 12 11 f2 6600 0 15 090 63 0.80 2 73 0 37 0.37 0.00 12 N-12 P-11 11 10 11 0 0 00 090 63 0.80 2 73 0 00 0 37 0.00 12 N-12 P-10 10 3 10 0 0 00 0 90 63 0.80 2 73 o oa 0 37 0.00 12 N-12 P-3 3 2 3 485 0 01 0 90 63 0.80 2 73 047 0 85 1.27 12 N-12 P-2 2 1 2 a 0 00 0 90 63 0.80 2 73 0 00 085 0.00 12 N-12 7085 0.16 0.90 CB-9 TO CB-7 P-9 9 7 9 1957 004 0 90 63 0.80 2.73 0.11 0 11 0.00 12 N-12 ' I Slope invert invert over-a V Bend CB m ool flow Full Full Dia elev Flow Fl= ft % fl ft fl ct, '"' 0 012 82 7 01 425 15 419 40 428 40 10 25 13 05 90 2 0 012 24 12.08 419.40 416 50 426 65 1345 17.13 0 4 0 012 25 1.00 421.66 421 41 424 91 3.87 4 93 90 2 0012 106 1.00 421.41 420 35 424 91 3.87 4 93 90 2 0.012 25 15.40 420 35 416 50 426.64 1519 19.34 0 4 0012 132 4.46 430 59 424 70 433 42 818 10.41 0 2 0.012 151 2.93 424.70 420 28 428 40 662 8.43 49 2 0.012 11 17.73 42028 416.33 425.28 16.29 20.75 49 2 0.012 134 0.80 418.33 417.26 424 41 3.46 4.40 64 4 0 012 8 1.00 417 26 417.18 419 88 3.87 4.93 68 2 0 012 73 3.42 421.90 419.40 424.90 7. 16 9.12 90 2 Pipe P-8 Path R \2016\0\ 16062\3\Documents\Analysis\KCBWI 161212\BACKWATER-16062_ 100.xls Storm Water Runoff Variables: A= Total of Subasin and Tributary Areas C= Runoff Coefficient (the anticipated proportion of rainfall volume that runs off the area) see '09 KCSWM Table 3.2. 1A Cc= Composite Runoff Coefficient Cc= S(Cn'A0 )/Aroi., T ,= Time of Concentration (Typically 6.3 minutes which is the mrn1mum value used 1n calculat1ons) R= design return frequen_st iR= Unil peak rainfall intensity factor iR= (aA)(T0 )~(-bR aH,bR-coefficients from '09 KCSWM Table 3.2.1. B used to adJust the equation for the design storm IR= Peak rainfall 1ntens1ty factor for a storm of return frequency 'R' IA= P,{1R PR= total prec1p1tat1on (inches) for 1he 24--hour storm event for the given frequency. See lssopluvial Maps in '09 KCSWM Figures 3.2.1.D QR= peak flow (els) for a s1orm of return frequency 'R' QR"' Cc'IR'A The Q-Ralio describes the ratio of the tnbutary flow to the main upstream flow. R• 8R" bR"' PA= 100 -year storm 2.61 063 3.9 inches Conveyance System Variables: d= pipe diame1er n= Manning's Number I= Length of pipe Structures Subasins & Tnbutanes FROM CB To CB 6 7 8 A A C c, T, sf Ac Ac M<a CB-8 TO INLET 2 10226 0.23 0.58 6.3 '" ,, Os so, Q-d Material subasin Ratio ct, ct, '" 082 3.19 0.43 0.43 0 00 12 N-12 FROM RUN 9-7 1957 0.04 0.90 I P-7 7 INLET 2 7 794 0.02 0.90 P-7 7 INLET 2 7 2751 0.06 0.90 6.3 0.82 319 0 16 0.61 0 30 12 N-12 12977 0.30 0.64 CB-6 TO INLET 1 P-6 6 5 6 30608 0.70 0.59 6.3 0.82 3.19 1.33 1.33 ODO 12 N-12 P-5 5 4 5 28631 0.66 0.59 6.3 0.82 3.19 1.23 2.56 0.48 12 N-12 P-4 4 INLET 1 4 7B5 0.02 0.90 6.3 0.82 3.19 0.05 2.61 0.02 12 N-12 60024 1.3B 0.69 CB-11 TO CB-1 P-12 12 11 12 6600 0 15 090 6.3 0.82 3 19 D 44 044 0.00 12 N-12 P-11 11 10 11 0 0.00 090 6.3 0.82 3 19 DOO 0.44 0.00 f2 N-12 P-10 10 3 10 0 0.00 090 6' 0.82 3.19 000 0.44 0.00 f2 N-12 P-3 3 2 3 485 0.01 0.90 ,., 0.82 3 19 048 0.91 1.10 12 N-12 P-2 2 1 2 0 0.00 0 90 6' 0.82 3.19 ODO 091 0.00 12 N-12 7085 0.16 0.90 CB-9 TO CB-7 P-9 9 7 9 1957 0.04 0.90 ,., 0.82 3.19 0.13 0.13 0.00 12 N-12 " I Slope invert invert over-a V Bend CB '" oot flow Full Full Dia elev. Flow Flow ff % fl fl fl ct, fos 0 012 82 7.01 425.15 419.40 428.40 10.25 13.05 90 2 0.012 24 12.08 419.40 416.50 426.65 13.45 17.13 0 4 0 012 25 1.00 421.66 421.41 424.91 3.87 4.93 90 2 0 012 106 1.00 421.41 420.35 424.91 3.87 4.93 90 2 0.012 25 15.40 420.35 416.50 426.64 1519 19.34 0 4 0.012 132 4.46 430.59 424.70 433.42 8.18 10.41 0 2 0.012 f5f 2.93 424 70 420 28 428.40 6.62 8.43 49 2 0.012 11 17.73 420.28 418 33 425.28 16.29 20.75 49 2 0 012 134 0.80 418.33 417.26 424.41 346 440 64 4 0 012 B 1 00 417.26 417.18 41988 '87 493 66 2 0 012 73 342 421 90 419.40 424 90 7.16 912 90 2 FIGURE 18 BACKWATER ANALYSIS MAP ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 56 Bethany Corner Renton, Washington " "' I\~ LOT CB-6 22,584 S.F. I I .. I I I I I I IRhW ,r,q_ 6 I I I I 8 006 S.F. ' ROADA ROW CB-5 j 6, ::J' u ::>.t. i I I I I I I I I I I I LOT CB-5 22,103 S.F. 11.'i ! /1 I I f r I I I' I 11 I I ' I 11 i I LOT CB-8 1 I I I ROW CB-8 7,119 S.F. I· L,--H-3107 S.F. 1 -I i 1,1/ I [ I i C/j 1. I I~ J1 I I"( , ' I m I i~ ., ~ ~~ if!; 11 ~ § i ~ I I i I. ' ~ 0 \l ~, 9:j' I~ . I I~ ROW CB-4 ~ I I \ I i ' J I ., SD VAULT 7,348 SF. - .. . .. .,,,.. I i.,... I y7B5 S.F. :/ + /I/ ! ,, . ' I ~ I ~ ROW CB-7 , 794 S.F. . I ' I I. ,, : ROW CB-9 I 1'""" 1,957 S.F. I IV" Ip~ i I I I I ti I i I I f I ROW CB-3 r-:~ I ~ 'f 485 S.F. I ~r I , I L~ ci) ~ ~ !l:: ~ ~ ln~ ~ ~<(~ ~ 8~~- (j i:~ ~ i;;:!~ • • lJ.J ... CC) a:i "O i ~ :::5 ~ it ORAFTcD BY: Cm' O£SKiN£D BY: CYW PRo.ECT £NGINffR: MAJ OAT£: ta28.16 PRQ.ECT NO.: 16062 I f7WR£; 18 R; \2016\0\l6062\J\Orowin911\Plots\Ngure~\la-JBW. 16062.dwg 12/12/2076 4-:32:47 PM PDT COP'!'RIGHT @ 2016, D.R. STRONG CONSUL TING ENGINEERS INC. I I BACKWATER ANALYSIS RESULTS BACKWATER COMPUTER PROGRP~ FOR PIPES Pipe da:a .:"rom file:CB-6 TO :NLET l.bwp Surcharge condi:ion a: intennediate junctions Tailwater Elevation:423.61 feet Discharge Range:2.11 to 2.6::_ Step Df G.1 [cfs] Overflew Elevation:424.91 feet ~eir:::.JONE Upstream Velocity:O . .:ee:/sec PIPE NC. 1: 25 LF -12"CF @ 15.400 OUTLET: 416.50 INLE~: 420.35 INTYP: 3 JUNC )10. 1: OVERFLOW-EL: 426.64 BEND: 0 DEG DIA/WI~TE: 4.0 Q-RATIO: 0.02 Q(CFS) EW (FT) HW E:=,2:v. * N-FAC DC ON JO DE HWO HWI *************~*~*~************~***x***************************~********~******* 2.E 3. 4C 423. 75 * 0.012 0.63 C.26 7 .11 7.11 3.34 3. 4 0 0. 77 2 .21 3.41 423.76 * 0. 812 0. 64 C.26 7 .11 7.11 3 . .34 3.C 0.80 2.31 3.43 423.78 * 0.012 0.66 0.27 7 .11 7 .11 3.35 3.43 0.82 2.41 3.44 423.79 * 0.012 0.67 0. 27 7 .11 7.11 3.36 3. 4 4 0. 8 4 2.51 3.46 423.81 * 0.012 0.68 0.28 7 .11 7 .11 3.37 3. 4 6 0.86 2. 61 3.47 42 3. 82 * 0.012 0. 78 0. 29 7 .11 7 .11 3.37 3.47 J.88 2. 61 3.47 423.82 * 0.012 0.70 0.29 7.11 -I .11 3.37 3.47 0.88 PI?E NO. 2: 106 LF -12"CP @ 1. 00% OUTLET: 420.35 INLET: 421.41 INTYP: 5 JCNC NO. 2: OVERFLOW-EL: 424.91 BEND: 90 DEG O:P../WID':'.:'H: 2.0 Q-RATIO: 0.48 Q(C?S) HW(FT) HW ELEV. * N-FAC DC CN TW DO JE HWO HWI *********************************•*•*•********•******•*****~**************•*•*• 2.07 2.84 424.23 * 0.012 0.62 0.53 3.40 3.40 2.65 2.84 0.97 2.17 2.90 424.31 * 0.012 0.63 0.54 3.41 3. 41 2.69 2.90 1. 00 2.27 2. 96 424.37 * 0.0~2 0.63 0. 56 3.43 3.43 2.73 2.96 1. 04 2.36 3.03 424. 44 * 0.0~2 0.66 0.57 3. 44 3. 4 4 2.78 3.C3 1. 07 2. 4 6 3.10 424.51 * O.Ol2 0.68 0.59 3.46 3.46 2.83 3.10 1.11 2.56 3 .17 424.58 * 0.012 0.69 0.60 3.47 3.47 2.88 3.17 1.14 2.56 3 .17 424.58 * 0.012 0.69 0.60 3.47 3.47 2.88 3.17 1.14 PIPE NC. 3: 25 I.F -12 11 cP il 1. CO% OUTLET: 42:.41 INLE~: 42:_. 66 INTY?: 5 Q (CFS) ~W(?T) HW ELEV. * N-FAC DC DN TW DO D~ HWO HWI ******•*•***•*******•***•*•*********************************•********•********* 1. 40 2. 70 424.36 * 0.012 0.51 0.42 2.84 1. 4 6 2. 77 424.43 * 0.012 C.32 0.43 2.90 1. 53 2.84 424.50 * 0.012 0.53 0.44 2.96 1. 60 2.92 424.58 * 0.012 0.54 0.45 3.03 1. 66 3.00 424.66 * 0.012 0.55 0.46 3.10 1. 7 3 3.09 424. 75 * 0.012 0.36 0.47 3.17 1. 73 3.09 424.75 * 0.012 0. 56 0 .4 7 3.17 BACKWATER COMFC~ER PC\OGRAM FOR PIPES Pipe data from file:C3-8 ~o INLET 2 .bwp Surc~arge conCition at intermed~ate junctions Tai:water Elevation:423.61 feet 2.84 2.90 2.96 3.03 3 .10 3 .17 3 .17 ~~scharge Range:0.11 to 0.61 Step cf 0.1 [cfs] Overflow Elevation:428.4 feet Weir:NONE Upstream Velocity:C. feet/sec ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 57 2. 63 2.70 2. 68 2. 77 2.75 2.84 2.82 2.92 2.90 3.00 2.98 3.09 2.98 3.09 0. 72 0.74 o. 77 0.79 0.81 0.83 0.83 Bethany Corner Renton, Washington PIPE 'IC. 1: 24 LF -12"C? @ 12. 08% OUTLET: 416.50 INLET: L9.40 INTYP: 5 JUNC :,.JC. 1: OVERFLOW-EL: 42 6. 65 BEND: 0 DEG 0IA/WIDTH: 4. 0 Q-AAT10: 0.30 Q(CFS) HW (FT:1 HW ELEV. * N~FAC DC ON TW DO JE HWO HWI ******************************************************************************* 0 .11 4.22 42 3. 62 * 0.012 C.14 0.07 7 .11 7 .11 4.22 4.22 C.12 0.21 4. 2c 423.61 * 0.012 C.19 0. 09 7 .11 7 .11 4.21 4 .21 0.19 0.31 4.21 423.61 * 0.012 0.23 C.11 7 .11 7 .11 4.21 4.21 0.25 0.41 4.22 42 3. 62 * 0.012 0.27 C.12 7.11 7 .11 4.21 4.22 0.30 0.51 4.22 42 3. 62 * 0.012 0.30 C .14 7 .11 7. cl 4.21 4.22 0.34 0.61 4.23 42 3. 63 * 0.012 0.33 0.15 7 .11 7. cl 4 .22 4.23 0.38 PIPE NO. 2: 82 LF -12"CP @ 7.0lt OUTLET: 419.40 INLET: 425.15 INTYP: 5 Q(CFS) HW (FT) EW ELEV. * N-FAC DC DN ~w DO 02 H!,O HWI ******************************************x*******x*x*~***X******************** 0.08 0.12 425.27 * 0.012 0.12 0.07 4.22 0.16 C.19 425.34 * 0.012 0 .17 0.09 4.21 0.24 C.24 425.39 * 0.012 0 .2:. 0 .11 4.L 0.32 0.28 425.43 * C. C12 0.24 0.13 4.22 0.39 0.32 425.47 * C.012 0. 26 0.14 4.22 0. 47 0.35 425.5C * 0.012 0. 29 0. :..s 4.23 BAC@1.1A~ER COM?UTER PROGR.~ FOR PIPES Pipe data from file:CB-9 TO CB-7.bwp Surcharge condition at intermeCiate ju~ctions Tailwate~ Elevaticn:423.63 feet 4.22 4.L 4. 2c 4.22 4.22 4.23 Lisctarge Range:0.02 tc 0.13 Step cf 8.02 [cfs] Overflow ~leva~icn:424.9 feet Weir:NONE Upst~eam Veloc~ty:0. feet/sec 0 .12 ****" 0. 12 C.17 ****"' 0.19 C.21 ****"' 0.24 C. 24 ***** 0.28 G.26 ***** 0.32 0.29 *"'*** 8. 35 PIPE NO. 1: 73 LF -:..2"CP @ 3.42', OUTLET: C9.40 IN~ET: 421.90 INT~P: 5 Q(CFS) HW (FT) :1W ELEV. N-rnc DC ON TW DO DE HWO HWI *******************w**********"'*****"'*******"'*"'**************"'***************** O.C2 c. 74 423. 64 • 0.012 0.06 0.04 4.23 C.C4 :. . 7 3 423.63 * 0.012 0.09 0.06 4.23 0.06 1. 73 42 3. 63 * 0.012 0.10 0.07 4.23 0.08 1. 73 423.63 * 0.012 0.12 0.08 4.23 0.10 1. 73 423.63 * 0.012 0.13 0.09 4.23 0.12 1. 7 3 423.63 * 0.012 0.15 0.10 4.23 0.14 1.73 42 3. 63 * 0.012 0.16 0.10 4.23 3ACKWATER COMPUTER PROG? . .I\M FOR PIPES Pipe data from file:CB-11 ~o CB-1.Dwp Surcharge condi~ion at i~termediate jcnctio~s Tailwater Elevation:418.18 feet 4.23 4.23 4.23 4.23 4.23 4.23 4.23 Discharge Range:0.11 to 0.91 Step of 0.1 [cfs] Overflow Elevation:433.42 =eet Weir:NONE UpstreaJn Velocity:O. feet/sec 1. 74 1. 74 0.06 l. 73 1. 73 0.09 :.. . 73 1. 73 0.12 c. 73 1. 73 0 .14 : . 73 1. 73 0.16 -_. 73 1. 73 0.17 :. . 73 1. 73 0.19 PIPE NO. l: 8 LF -12"CP @ OVER?LOW-EL: 419.88 1.00% OUTLET: 417.18 INLET: 417.26 I'ITYP: 5 JUNC NO. 1: ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report BEND: 68 DEG DIA/WDTH: 2. 0 Q-RATIO: 0. 00 Page 58 Bethany Corner Renton, Washington Q {CFS) HW [FT) HW ELEV. * N-FAC DC ON TW DO DE HWC HWI ******************************~************************************************ 0 .11 0.93 418.19 * 0.012 0.14 0.12 1. 00 1. 00 0.93 0.93 C.18 0.21 0.93 418.19 * 0.012 0.19 0.16 1. 00 1. 00 0.93 0.93 0.25 0.31 C,. 93 418.19 * 0.812 0.23 0.20 1. oc 1. 00 0.93 0.93 0.31 0. 41 C.94 418.20 * 0. 012 0.27 0.23 1. 00 1. oc 0.93 0.94 0.36 C.51 C.94 4:8.20 * 0.012 0.30 0.25 1. 00 1. oc 0.93 0.94 0.40 C.61 G.94 4:_3. 20 * 0.012 0.33 0.27 l. 00 1. oc 0.93 0.94 0.44 0.71 0.95 418.2: * 0.012 0.36 0.30 :.oo 1. 00 0.93 C.95 0.48 0.81 0.95 418.2: * 0.012 0.38 0.32 :.oo 1. 00 0.93 C.95 0.52 0.91 0.96 418.22 * C.012 0. 4 0 0.34 1.00 1. 00 0.93 0. 96 0.55 PIPE NO. 2: 134 LF -12"C? @ 0.80% OUT:.ET: 417 .26 INLET: 418.33 INTYP: 5 JUNC NO. 2: OVER,LOW-EL: 424 .L BEND: 64 DEG DIA/WID':'.:'H: 4.0 Q-RATIO: 1.10 Q(CFS) EW (FT) HW ELEV. * N-FAC DC JN ':W DO DE HWO HWI ******~**************************************w****w****************•*•*****•*** 0.L 0.18 418.51 * 0.012 0.14 0.13 0.93 0.93 0. ::_4 **"'*"' 0.18 0. 2: 0.25 418. 58 * 0.012 0. l_9 0.: 7 0.93 C.93 0. ::_ 9 ** **"' 0.25 0.3: 0.31 418. 64 * 0.012 0. 23 '.J. 21 0.93 C.93 0. 23 ****• 0.31 0. 41 0. 36 418.69 * 0.012 0.27 0.24 0. 94 G. 94 0.27 ***** 0.36 0.51 0.4C 418. 73 * 0.012 C.30 0. 2 6 0.94 0. 94 0.30 ***** 0.40 0.61 0.4S 418. 78 * 0.012 0.33 0. 2 9 0.94 0. 94 0.33 ***** 0.45 0. 71 8.49 418.82 * 0.012 C.36 0.31 0.95 0.95 C.36 ***** 0.49 0.81 0.52 418.85 ' 0.012 0.38 0.33 0.95 0.95 C. 38 *•*** 0. 52 0.91 0.56 418.89 ' 0.012 0.40 0.36 0.96 0.96 C.40 *"'*** 0.56 PIPE NO. 3: 11 LF -l2"CP ,, 17.73% OUTLET: 418.33 INLET: 420.28 INTYP: 5 JUNC NO. 3: OVERFLOW-EL: 425.28 3END: 49 QEG DIA/WIJTH: 2.0 Q-,U'.TIC: 0.00 QIC?S) HW{FT) EW ELEV. * N-f.z:i..c DC ON TW DO DE fiWO HWI •**********************"'*"'*"'****"'*****"'**********r***************************** C.C5 C.10 420.38 * 0.012 0.10 0.05 0.18 0.18 0.10 ***** 0.05 0.10 0.13 420.41 * 0.012 0.13 0.06 0.25 0.25 0 .13 ***** 0.08 0.15 0.16 420.44 * 0.012 0.16 0.07 0.31 0.31 0.16 ***** 0.12 0.20 0.19 420.47 * 0.012 0.19 0.08 0.36 0.36 0.19 ***** 0.16 0.24 0.21 420.49 * C.012 0. 2: 0.09 0.40 0. 40 0.21 ***** 0.19 0.29 0.23 420.51 * C. 012 0 .23 0 .10 0.45 0.45 0.23 ***** 0.21 0.34 0.25 420.53 * C. 012 0 .25 0.10 0.49 0.49 0.25 ***** 0.24 0.39 0. 26 420.54 * 0.012 0. 26 0 .11 0.52 0.52 0. 26 ***** 0.26 0.43 0.28 420.56 * C.C12 0.28 0.12 C.56 0.56 0.28 ***** 0.28 PIPE NC. 4: 151 LF -12"C? @ 2. 93 9; OU Tl ST: 420.28 INLET: 424. 70 INTYP: 5 JUNC NC. 4: OVERFLOW-EL: 428.40 BEND: 49 DSG DIA/WIDTH: 2.0 Q-RATIO: 0.00 Q(CFS) ~W [?T) HW ELEV. * N-FAC DC ON ~w DO DE HWO HWI **w***~*~*~*****"'**********************•**********7(****************"'*********** 0.05 O.E 424.81 * 0.0:2 O.lC 0.07 0.10 0.16 424.86 * 0.0:2 0.13 0.09 0.15 0. 20 424.90 * 0.012 0 .16 0 .11 0. 20 0. 23 424.93 * 0.012 0.:.. 9 0.12 0.24 0. 26 424.96 * 0.012 0.21 0.14 0 .2 9 0. 29 424.99 * 0.012 0. 23 8. J.5 0.34 0.31 425.01 * 0.012 0. 25 0.16 0.39 0.33 425.03 * 0.012 C. 26 0.17 0. 43 0.36 425.06 * 0.012 C.28 0.18 ?:PE NO. 5: 132 LF -12"CP @ 4. 4 6°, OUTLET: ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 59 0.10 0 .13 0.16 0.19 0.21 0.23 0.25 0.26 0.28 424.70 0.10 0.10 "'**** 0. 1.1 0.13 0.13 -,,:**** 0.16 0.16 0.16 **-,,** 0.20 0.19 0.19 **-,,** 0.23 D. 21 0. 21 **•** 0.26 C.23 0. 23 * * * *.,, 0.29 0.25 0.25 ****7( 0.31 0.26 0. 26 ***** 0.33 0.28 0.28 ***** 0.36 INLE~: 43C.59 I::-JTYP: 5 Bethany Corner Renton, Washington Q(CFS:, HW(FT) HW ELEV. * N-FAC DC ON TW GO DE HWO HWI *********************************************************************"********* 0.05 0.10 430.69 * c.0:2 0.10 0.15 430.74 * O.C12 0.15 0.19 430.78 * 0. Cl2 0. 20 0.22 430.81 * O.Cl2 0.24 0.25 430.84 * 0.012 0. 29 0.28 430.87 * 0.012 0.34 0.31 430.9C * 0.012 0.39 0.33 430.92 * 0.012 0. 4 3 0.35 4 3 0. 94 * 0.012 ©2016 D. R STRONG Consulting Engineers Inc. Technical Information Report 0.10 0.06 0.13 0.08 0.16 0 . .:..o 0 .19 0. '._l 0.21 0.12 0. 23 C.13 C. 25 C.14 0. 26 C.15 C.28 0.16 Page 60 0.11 0 .11 0.10 0.16 0.16 0.13 0.20 0.20 0.16 0.23 0.23 0. 19 0.26 0. 26 0.21 0.29 0.29 C.23 0.31 0.31 C.25 0.33 0.33 0.26 0.36 0.36 C.28 ""*-tr** **-,..** **""** **** >< ****" * * * * 1< ****"' ·k * * ... * ***** 0.10 0.15 0.19 0.22 0.25 0.28 0.31 0.33 0.35 Beth any Corner Renton, Washington SECTION VI SPECIAL REPORTS AND STUDIES The following report and studies have been provided with this submittal. Critical Areas Study: Mark Rigas, P.E. -December 10 5 1, 2016 Subsurface Exploration and Geotechnical Engineering Report: Associated Earth Sciences Incorporated -December 16, 2016 Arborist Report: Tree Harmony Arborists, LLC -December 12, 2016 ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 61 Bethany Corner Renton, Washington SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS None at this time. ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 62 Bethany Corner Renton, Washington SECTION VIII CSWPPP ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design will meet the seven minimum King County requirements: 1. Areas to remain undisturbed shall be delineated with a high visibility plastic fence prior to any site clearing or grading. 2. Site disturbed areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. A stabilized construction entrance will be located at the point of ingress/egress (i.e. onsite access road). 5. The detention pond will act as a sediment pond for sediment retention. Perimeter silt fences will provide sediment retention within the bypass areas. 6. Surface water from disturbed areas will sheet flow to the sediment pond for treatment. 7. Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would impact roadways, drainage ways, surface waters, or neighboring residences. SWPPP PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP's listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSO) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 63 Bethany Corner Renton, Washington 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. The complete CSWPPP can be found in Appendix B. ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 64 Bethany Corner Renton, Washington SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 1. Bond Quantity Worksheet -is located in Appendix C 2. The Stormwater Facility Summary Sheet is included in this section ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Page 65 Bethany Corner Renton, Washington STORMWATER FACILITY SUMMARY SHEET Development __ --=B:.:e:.:t:..:.h:::.a:..:.nv.1....::C:.:o:..:r""'n"'e"-r------Date December 15, 2016 Location: 16433 & 16451 111 1h Avenue SE, Renton, Washington ENGINEER Name Jonathan S. Murray, P.E. Firm D. R. STRONG Consulting Engineers, Inc. Address 620 7'" Avenue Kirkland, WA 98033 Phone (4251827-3063 Developed Site: 1.942 acres Number of lots: _!! DEVELOPER Name Mark Seek Firm Address ... 15233 Manion Way NE Duvall, WA 98019 Phone (425) 919-4062 Number of detention facilities on site: Number of infiltration facilities on site: __ 1,.__ vaults vaults ___ pond ponds ___ ~n~ ~n~ Flow control provided in regional facility (give location) ____________ _ No flow control required Exemption number _____________ _ Downstream Drainaae Basins Immediate Major Basin Basin Benson Green/Duwamish River Watershed Number & type of water quality facilities on site: ___ biofiltration swale (regular/wet/ or continuous inflow?) ___ sand filter (basic or large?) large?) 1 combined detention/WO vault ___ combined detention/wetpond ___ compost filter ___ filter strip ___ flow dispersion ___ farm management plan ___ landscape management plan ___ sand filter, linear (basic or ___ CONTECH Stormfilter ___ sand filter vault (basic or large?) ___ stormwater wetland ___ wetvault (basic or large?) ___ Wetvault ___ pre-settling pond ___ flow-splitter catchbasin ___ oil/water separator (baffle or coalescing plate?) ___ catch basin inserts: Manufacturer ____________________ _ ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 66 Bethany Corner Renton, Washington ---pre-settling structure: Manufacturer -------------------- DESIGN INFORMATION INDIVIDUAL BASIN Water Quality desian flow Water Quality treated volume Drainaae basin(s) 1 Onsite area (includes frontaae) 1.942 Offsite area 0.0 Type of Storage Facility Detention Vault Live Storaqe Volume (required) 22,080 Predev Runoff Rate 2-vear 0.061 10-year 0.103 100-vear 0.176 Developed Runoff Rate 2-vear 0.032 (includes bypass) 10-vear 0.095 100-vear 0.456 Type of Restrictor Size of orifice/restriction No. 1 0.75" 0 0.00' No. 2 1.375" 0 3.23' No. 3 ©2016 D.R. STRONG Consulting Engineers lnc. Technical Information Report Page 67 Bethany Corner Renton, Washington SECTION X OPERATIONS AND MAINTENANCE MANUAL The Home Owners Association will be responsible for maintenance of several private catch basins on various lots as depicted on the plans. Maintenance guidelines set forth in the 2009 KCSWDM are included in this section. All other drainage elements are to be publicly maintained. ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 68 Bethany Corner Renton, Washington APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE. AND WQ FACILITIES NO. 3 -DETENTION TANKS AND VAULTS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Perfonned Site Trash and debris 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 ~ 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 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 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. Tank or Vault Trash and debris Any trash and debris accumulated in vault or tank No trash or debris in vault. Storage Area (includes floatables and non-floatables). Sediment Accumulated sediment depth exceeds 10% of the All sediment removed from storage accumulation diameter of the storage area for~ length of area. storage vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than X length of tank. Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of Any part of tank/pipe is bent out of shape more Tank repaired or replaced to design. shape than 10% of its design shape. Gaps between A gap wider than Yz-inch at the joint of any tank No water or soil entering tank sections, damaged sections or any evidence of soil particles entering through joints or walls. joints or cracks or the tank at a joint or through a wall. tears in wall Vault Structure Damage to wall, Cracks wider than %-inch, any evidence of soil Vault is sealed and structurally frame, bottom, and/or entering the structure through cracks or qualified sound. top slab inspection personnel determines that the vault is not structurally sound. Inlet/Outlet Pipes 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 %-inch wide at inlet/outlet 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 l/9/2009 A-5 APPENDIX A MAfNTENANCE REQUREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 3 -DETENTION TANKS AND VAULTS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Pelformed Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Manhole access covered. Any open manhole requires immediate maintenance. Locking 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 Cover/lid difficult 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 person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access Damaged or difficult Large access doors or plates cannot be Replace or repair access door so it doors/plate to open opened/removed using normal equipment. can opened as designed. Gaps, doesn't cover Large access doors not flat and/or access Doors close flat and covers access completely opening not completely covered. opening completely Lifting Rings missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to lift or rusted or plate. remove door or plate. I/9/2009 2009 Surface Water Design Manual -Appendix A A-6 APPENDIX A MAINTENANCE REQUIREME:-ITS FOR FLOW CONTROL, CONVEYANCE, A'-10 WQ FACILITIES NO. 4 -CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Perfonned Structure Trash and debris Trash or debris of more than Y2 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 of the FROP·T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP· T section Damage to frame Corner of frame extends more than 'X inch past Frame ls 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 Y.. inch. Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than :X inch of the frame from the top slab. Cracks in walls or Cracks wider than Yz 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 Yz inch and longer than 1 foot No cracks more than 1 /4 inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe of soil particles entering structure through cracks. Settlement/ Structure 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 Yz·inch at the joint of the No cracks more than %·inch wide at inlet/outlet pipes or any evidence of soil 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 pollutlon 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 rungs 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 pClsition (allow up lo 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 holes-in the Structure 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 MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily and maintenance person. is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due !o Plate is in place and works as missing, out of place, or bent orifice plate. designed. Obstructions Any trash, debris, sediment, or vegetation Ptate is free of all obstructions and blocking the plate. works as designed. Overflow Pipe Obstructions Any !rash 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 overflow 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 inleVoutlet No trash or debris in pipes. pipes (includes floatables 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 soil entering the joint of lhe inlet/outlel pipe. at the joints of the inleVoutlet pipes. Metal Grates Unsafe grate opening Grate with opening wider than 7 /8 inch. Grate opening meets design (If Applicable) 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 is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. 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 cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult 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 person. I 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 lhe 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 more than X 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 cou!d 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 :X 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 Y. inch. Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than ~ inch of the frame from the top slab. Cracks in walls or Cracks wider than 12 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 Y:i inch and longer than 1 foot No cracks more than 1 /4 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 %-inch at the joint of the No cracks more than Y.-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the catch basin at the joint of the inleUoutlet 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. 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 X-inch at the joint of the No cracks more than X-inch wide at inlet/outlet 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 l/9/2009 A-9 APPENDIX A MAIJ,;TENANCE REQUIREMENTS 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 Perfonned Metal Grates Unsafe grate opening Grate with opening wider than 7/s inch. Grate opening meets design (Catch Basins) 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 is 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 place. 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 cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One m ai ntenan ce person can not remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs. of lift. reinstalled by one maintenance person. l/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 public 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 than a surface oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion observed 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 feel or more, any exposed native Applicable) soil. 2009 Surface Water Design Manual~ Appendix A l/9/2009 A-II APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 10 -GATES/BOLLARDS/ACCESS BARRIERS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Chain Link Fencing Damaged or missing Missing gate. Gates in place. Gate members Broken or missing hinges such thal 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 does not lock gate not link to all parts. opening of gate Openings in fabric Openings in fabric are such that an 8-inch Fabric mesh openings within 50% of diameter b~II could fit through. grid size. Bar Gate Damaged or missing Cross bar does not swing open or closed, is Cross bar swings fully open and cross bar missing or is bent to where it does not prevent closed and prevents vehicle access. vehicle access. Locking mechanism Locking device missing, no-functioning or does Locking mechanism prevents does not lock gate not link to all parts. opening of gate. Support post Support post does not hold cross bar up. Cross bar held up preventing vehicle damaged access into facility. Bollards Damaged or missing Bollard broken, missing, does not fit into support No access for motorized vehicles to hole or hinge broken or missing. get into facility. Does not Jock Locking assembly or lock missing or cannot be No access for motorized vehicles to attached to lock bollard in place. get into facility. Boulders Dislodged Boulders not located to prevent motorized vehicle No access for motorized vehicles to access. get into facility. Circumvented Motorized vehicles going around or between No access for motorized vehicles to boulders. get into facility. 2009 Surface Water Design .\1anual -Appendix A 1/9/2009 A-15 APPENDIX A MAfNTENA"iCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 11 -GROUNDS (LANDSCAPING) Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Perfonned 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. r~gulations. No danger of noxious vegetation where County personnel or the public 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 than a surface oil film. Grass/ground cover 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 identified 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 Trees and shrubs with less than 5% broken which affect more than 25% of the total 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 or of the roots. diseased trees removed. l/9/2009 2009 Surface Water Design Manual -Appendix A A-16 APPENDIX A MAINTENAI\CE REQUIREMENTS FOR FLOW CONTROL. CONVEYA>ICE, AND WQ FAClLlTIES NO. 12 -ACCESS ROADS Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Perfonned Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway drivable by maintenance square feet (i.e., trash and debris would fill up vehicles. one standards size garbage can). Debris which could damage vehicle tires or Roadway drivable by maintenance prohibit 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 prevents Road drivable by maintenance potholes, soft spots, maintenance access. vehicles. ruts Vegetation on road Trees or other vegetation prevent access to Maintenance vehicles can access surface facility by maintenance vehicles. facility. Shoulders and Erosion 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 missing modular block. road infiltrates. 2009 Surface Water Design Manual~ Appendix A 1/9/2009 A-17 APPENDJX A MAINTENANCE REQUIREMENTS fOR FLOW CONTROL, CONVEYANCE, Ai'iD WQ FACILITIES NO. 17 -WETVAULT Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Perfonned Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Treatment Area Trash and debris Any trash and debris accumulated in vault No trash or debris in vault. (includes floatables and non-floatables). Sediment Sediment accumulation in vault bottom exceeds No sediment in vault. accumulation the depth of the sediment zone plus 6 inches. 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. Vault Structure Damage to wall, Cracks wider than %-inch, any evidence of soil Vault is sealed and structurally frame, bottom, and/or entering the structure through cracks, vault does sound. top slab not retain water or qualified inspection personnel determines that the vault is not structurally sound. Baffles dam aged Baffles corroding, cracking, warping and/or Repair or replace baffles or walls to showing signs of failure or baffle cannot be specifications. removed. Ventilation Ventilation area blocked or plugged. No reduction of ventilation area exists. 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 %-inch at the joint of the No cracks more than X-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. Grav~y Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won't seal Valve does not seal completely. Valve completely seals closed. Access Manhole Access cover/lid Access cover/lid cannot be easily opened by one Access cover/lid can be opened by damaged or difficult to person. Corrosion/deformation of cover/lid. one person. open Locking 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. Cover/lid difficult 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 person. Access doors/plate Large access doors not flat and/or access Doors close flat and covers access has gaps, doesn't opening not completely covered. opening completely. cover completely Lifting Rings missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to lift or rusted or plate. remove door or plate. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. 2009 Surface Water Design Manual -Appendix A 1/9/2009 A-23 APPENDICES ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 69 Bethany Corner Renton, Washington APPENDIX "A" LEGAL DESCRIPTION LOT 11, BLOCK 7, AKER'S FARMS NO. 6, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 42 OF PLATS, PAGE 15, RECORDS OF KING COUNTY, WASHINGTON; SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON. LOT 12, BLOCK 7, AKER'S FARMS NO. 6 ACCORDING TO PLAT RECORDED IN VOLUME 42 OF PLATS, PAGE 15, RECORDS OF KING COUNTY WASHINGTON. SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON. ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Page 70 Bethany Corner Renton, Washington APPENDIX "8" CSWPPP ©2016 D. R. STRONG Consulting Engineers Inc. Technical Information Report Page 71 Bethany Corner Renton, Washington Construction Stormwater General Permit Stormwater Pollution Prevention Plan (SWPPP) for Bethany Corner Prepared for: The Washington State Department of Ecology Northwest Regional Office 3190 161h Avenue SE Bellevue, WA 98008-5452 Permittee / Owner Developer Operator/ Contractor Mark Seek TBD TBD 15233 Manion Way NE Duvall, WA 98019 16433 & 16451111 1h Avenue SE, Renton, Washington Certified Erosion and Sediment Control Lead (CESCL) Name TBD Name Jonathan S. Murray, PE Activity / Phase Site Development Organization Associated Earth Sciences, Inc SWPPP Prepared By Organization DR Strong Consulting Engineers, Inc. SWPPP Preparation Date December 15, 2016 Project Construction Dates Start Date 4/2017 D.R. STRONG Consulting Engineers, Inc. Storrnwater Pollution Prevention Plan Contact Phone Number 425.827.7701 Contact Phone Number (425) 827-3063 End Date 10/2018 Bethany Corner Table of Contents 1 Project Information ............................................................................................................... 2 1.1 Existing Conditions ....................................................................................................... 2 1.2 Proposed Construction Activities... .. .................. 2 2 Construction Stormwater Best Management Practices (BMPs) ............................................ 4 2.1 The 12 Elements .......................................................................................................... .4 2.1.1 Element 1: Preserve Vegetation I Mark Clearing Limits ........................................ .4 2.1.2 Element 2: Establish Construction Access ............................................................ 5 2.1.3 Element 3: Control Flow Rates ............................................................................... 6 2.1.4 Element 4: Install Sediment Controls ........ 7 2.1.5 Element 5: Stabilize Soils ....................................................................................... 9 2.1.6 Element 6: Protect Slopes .................................................................................... 1 O 2.1. 7 Element 7: Protect Drain Inlets ............................................................................. 11 2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 Element 8: Stabilize Channels and Outlets ...... ............................... 12 Element 9: Control Pollutants .............................................................................. 13 Element 10: Control Dewatering ..... 16 Element 11: Maintain BMPs ................................................................................ 17 Element 12: Manage the Project.. ....................................................................... 18 3 Pollution Prevention Team ................................................................................................ 20 4 Monitoring and Sampling Requirements ............................................................................ 21 4.1 Site Inspection ............................................................................................................ 21 4.2 Stormwater Quality Sampling ................. 21 4.2.1 Turbidity Sampling ............................................................................................... 22 4.2.2 pH Sampling ........................................................................................................ 23 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies ......................... 24 5.1 303(d) Listed Waterbodies ......................................................................................... 24 5.2 TMDL Waterbodies ..................................................................................................... 24 6 Reporting and Record Keeping .......................................................................................... 25 6.1 Record Keeping .......................................................................................................... 25 6.1.1 Site Log Book ...................................................................................................... 25 6.1.2 Records Retention..................... .. ............... 25 6.1.3 Updating the SWPPP ........................................................................................... 25 6.2 Reporting .................................................................................................................... 25 6.2.1 Discharge Monitoring Reports ........ 25 6.2.2 Notification of Noncompliance .............................................................................. 26 D.R. STRONG Consulting Engineers. Inc. Stormwater Pollution Prevention Plan Page i Bethany Corner List of Tables Table 1 -Summary of Site Pollutant Constituents ................................................................. 2 Table 3-pH-Modifying Sources ............................................................................................ 15 Table 5 -Management ............................................................................................................ 18 Table 7 -Team Information .................................................................................................... 20 Table 8 -Turbidity Sampling Method .................................................................................... 22 Table 9 -pH Sampling Method .............................................................................................. 23 List of Appendices A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. Engineering Calculations D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page ii Bethany Corner List of Acronyms and Abbreviations Acronym / Abbreviation 303(d) BFO BMP(s) CESCL co, CRO CSWGP CWA DMR DO Ecology EPA ERO ERTS ESC GULD NPDES NTU NWRO pH RCW SPCC SU SWMMEW SWMMWW SWPPP TESC SWRO TMDL VFO WAC WSDOT WWHM Explanation Section of the Clean Water Act pertaining to Impaired Waterbodies Bellingham Field Office of the Department of Ecology Best Management Practice(s) Certified Erosion and Sediment Control Lead Carbon Dioxide Central Regional Office of the Department of Ecology Construction Stormwater General Permit Clean Water Act Discharge Monitoring Report Dissolved Oxygen Washington State Department of Ecology United States Environmental Protection Agency Eastern Regional Office of the Department of Ecology Environmental Report Tracking System Erosion and Sediment Control General Use Level Designation National Pollutant Discharge Elimination System Nephelometric Turbidity Units Northwest Regional Office of the Department of Ecology Power of Hydrogen Revised Code of Washington Spill Prevention, Control, and Countermeasure Standard Units Stormwater Management Manual for Eastern Washington Stormwater Management Manual for Western Washington Stormwater Pollution Prevention Plan Temporary Erosion and Sediment Control Southwest Regional Office of the Department of Ecology Total Maximum Daily Load Vancouver Field Office of the Department of Ecology Washington Administrative Code Washington Department of Transportation Western Washington Hydrology Model D.R STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 1 Bethany Corner 1 Project Information Project/Site Name: Bethany Corner Street/Location: 16433 & 16451 111 1 " Avenue SE City: Renton State: WA Zip code: 98055 Subdivision: N/A Receiving waterbody: Green/Duwamish River watershed 1.1 Existing Conditions Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 1.96 Disturbed acreage: 1.96 Existing structures: 0. 15 Landscape topography: 1.68 (estimate) Drainage patterns: 0.00 Existing Vegetation: 0.00 (estimate) Critical Areas (wetlands, streams, high erosion Stream and adjacent wetland risk, steep or difficult to stabilize slopes): 0.01 List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: Green River-Dissolved Oxygen, Temperature, Bioassessment, pH Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 -Summary of Site Pollutant Constituents Constituent Location Depth Concentration (Pollutant) No known contaminants exist on the Site 1.2 Proposed Construction Activities The applicant is seeking approval to subdivide 1.83 acres into nine single-family residential lots (Project), with lot sizes ranging from approximately 5,948 s.f. to 7,118 s.f. All existing improvements located on the Site will be demolished or removed during plat construction. The proposed impervious surface includes an internal plat road, Road A, which will have a proposed 53-foot right of way and will be improved with 26 feet of pavement , vertical curbs, 8' planter strip and 5' sidewalks. Frontage improvements will be made to 111 '" AVE SE, including catch basins, vertical gutter, and 5 foot sidewalk. Lot improvements will include single family residential houses and associated driveways. The total proposed impervious area for the Site is 50,896 s.f. D.R. STRONG Consulting Engineers, Inc. Storm water Pollution Prevention Plan Page 2 Bethany Corner Construction work will be completed under the Site Development permit. Activities will include installation of sewer, water and dry utilities; installation of storm sewer; construction of stormwater detention vault; road and sidewalks; and landscaping. Runoff will be collected and conveyed to the proposed detention vault. Appendix A shows the Site Plan with T.E.S.C. measures. Final stabilization of the disturbed land will include: • Asphalt roadway • Concrete sidewalks • Formal landscape planting Contaminated Site Information: No known contamination exists on Site. Proposed activities regarding contaminated soils or groundwater (example: on-site treatment system, authorized sanitary sewer discharge): Not applicable as no known contamination. D.R STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Bethany Corner Page 3 2 Construction Stormwater Best Management Practices (BMPs) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e., hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. 2.1 The 12 Elements 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits To protect adjacent properties and 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: The plastic or metal fence will be placed around the perimeter of the developable area of the Site. BMP will be implemented at the start of construction. Alternate BMPs for marking clearing limits are included in Appendix B as a quick reference tool for the onsite 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 CESCL will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are ineffective or failing. List and describe BMPs: High Visibility Plastic or Metal Fence (BMP C103) Silt Fence (BMP C223) Installation Schedules: Installation will occur before all other activity. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page4 Bethany Corner 2.1.2 Element 2: Establish Construction Access Construction access or activities occurring on unpaved areas will 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. Construction entrances will be installed in the location of the proposed access entrance, located on 111 th Avenue SE. Construction road and parking area stabilization will occur along this entrance. List and describe BMPs: Stabilized Construction Entrance (BMP C 105) Construction Road/Parking Area Stabilization (BMP C107) Installation Schedules: Installation will occur after the clearing limits are marked. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 5 Bethany Corner 2.1.3 Element 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. Once the detention vault is constructed, it will be utilized during construction as a flow control and sedimentation device. Discharge from the vault will be conveyed south to the existing storm conveyance system located in 111 1h Avenue SE. Alternate flow control BMPs are included in Appendix B as a quick reference tool for the onsite 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 B after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest As such, the project must comply with Minimum Requirement 7 (Ecology 2005). 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). Will you construct stormwater retention and/or detention facilities? rs] YesD No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? D Yesrsl No List and describe BMPs: Sediment Trap (BMP C240) Installation Schedules: Installation will occur before any grading occurs. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 6 Bethany Corner 2.1.4 Element 4: Install Sediment Controls Silt fence will be installed around the perimeter of the Site in areas where runoff could sheet- flow offsite. This BMP will be installed at the start of construction. Alternate sediment control BMPs are included in Appendix Bas a quick reference tool for the onsite 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 B 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 onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). 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 stormwater 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 permitted 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. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 7 Bethany Corner List and describe BMPs: Silt Fence (BMP C233) Interceptor Swale (BMP C200) Storm Drain Inlet Protection (BMP C220) Sediment Trap (BMP C240) Installation Schedules: These will all be installed before any grading occurs. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 8 Bethany Corner 2.1.5 Element 5: Stabilize Soils Temporary seeding and cover measures may be required for interim grading activity and at soil stockpiles. Permanent Seeding will occur as grading is completed. All stabilized sections will be seeded and vegetated. Nets and Blankets along with Plastic Covering will be used on all slopes of 2: 1 as shown on the plan. Dust Control will occur throughout the site as deemed necessary by the contractor and CESCL Alternate soil stabilization BMPs are included in Appendix B as a quick reference tool for the onsite 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 B after the first sign that existing BMPs are ineffective or failing. 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. West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 -September 30 7 days During the Wet Season October 1 -April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates: Start date: TBD End date: TBD Will you construct during the wet season? ~ YesD No List and describe BMPs: Temporary and Permanent Seeding (BMP C120) Nets and Blankets (BMP C 122) Plastic Covering (BMP C123) Dust Control (BMP C 140) Installation Schedules: These will all be installed before any grading occurs. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 9 Bethany Corner 2.1.6 Element 6: Protect Slopes Temporary slope protection measures may be required for interim grading activity and at soil stockpiles. Permanent Seeding will occur throughout the site as slopes are stabilized. Nets and Blankets along with Plastic Covering will be used on all slopes of 2:1 Checks Dams will be installed every 50' as shown on the plan. Alternate slope protection BMPs are included in Appendix B as a quick reference tool for the onsite 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 B after the first sign that existing BMPs are ineffective or failing. Will steep slopes be present at the site during construction? D Yes~ No List and describe BMPs: Temporary and Permanent Seeding (BMP C120) Nets and Blankets (BMP C 122) Plastic Covering (BMP C123) Check Dams (BMP C207) Installation Schedules: In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Bethany Corner Page 10 2.1.7 Element 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: • Storm Drain Inlet Protection (BMP C220) There are several existing catch basins which will require filters. 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 Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix B. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 11 Bethany Corner 2.1.8 Element 8: Stabilize Channels and Outlets Rip Rap (BMP C209) will be provided at all outlets. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 12 Bethany Corner 2.1.9 Element 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. Vehicles, construction equipment, and/or petroleum product storage/dispensing: • All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. • On-site fueling tanks and petroleum product storage containers shall include secondary containment. • Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. • In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. • Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Demolition: • Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (BMP C140). • Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C220 as described above for Element 7). • Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C152). Concrete and grout • Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151) Sanitary wastewater: • Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: • Solid waste will be stored in secure, clearly marked containers. Other: • Other BMPs will be administered as necessary to address any additional pollutant sources on site. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 13 Bethany Corner The project is not expected to exceed the 1,320 gallon stored-fuel threshold that requires developing a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act (CWA). List and describe BMPs: Dust Control measures (BMP C 140) Concrete Handling measures (BMP C151) Sawcutting and Surfacing Pollution Prevention measures (BMP C 152) Storm Drain Inlet Protection (BMP C220) Installation Schedules: Immediately following or in conjunction with activities. Inspection and Maintenance plan: Weekly Responsible Staff: CESCL Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? D Yes~ No List and describe BMPs: N/A Installation Schedules: N/A Inspection and Maintenance plan: Weekly Responsible Staff: CESCL Will wheel wash or tire bath system BMPs be used during construction? D Yes~ No List and describe BMPs: Presently not anticipated . SWPPP to be amended if wheel wash proves necessary. Installation Schedules: TBD Inspection and Maintenance plan: Weekly Responsible Staff: CESCL Will pH-modifying sources be present on-site? D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 14 Bethany Corner ~ YesD No Table 3 -pH-Modifying Sources LJ None LJ Bulk cement LJ Cement kiln dust LJ Fly ash L J Other cementitious materials lXI New concrete washing or curing waters L J Waste streams generated from concrete grinding and sawing LJ Exposed aggregate processes D Dewatering concrete vaults l2SI Concrete pumping and mixer washout waters L J Recycled concrete LJ Other (i.e., calcium lignosulfate) [please describe: l List and describe BMPs: Specific pH treatment measures to be determined by contractor and CECSL. Presently, CO2 sparging or dry ice anticipated approach if pH must be altered. Installation Schedules: prior to placement of concrete Inspection and Maintenance plan: Monitoring will occur at the time of concrete wash operations. Responsible Staff: CESCL Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 15 Bethany Corner 2.1.10 Element 10: Control Dewatering There will be no dewatering as part of this construction project. If excavation results in the requirement of dewatering, this SWPPP can be modified to include dewatering measures including control of discharge waters. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 16 Bethany Corner 2.1.11 Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 17 Bethany Corner 2.1.12 Element 12: Manage the Project Project management will incorporate the key components listed below: Table 5 -Management IX! Design the project to fit the existing topography, soils, and drainage patterns IX! Emphasize erosion control rather than sediment control IX! Minimize the extent and duration of the area exposed IX! Keep runoff velocities low IX! Retain sediment on-site IX! Thoroughly monitor site and maintain all ESC measures IX! Schedule major earthwork during the dry season l J Other (please describe) 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). 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; and o Limitations on activities and the extent of disturbed areas; and o 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: o 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 o Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 18 Bethany Corner 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: o Assess the site conditions and construction activities that could impact the quality of stormwater, and o 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. • If BMP(s) are deemed do not satisfy the requirements set forth in the General NPDES Permit (Appendix D), the CESCL will promptly implement one or more of the alternative BMPs listed in Appendix B after the first sign that existing BMPs are ineffective or failing. • Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling will occur at the baker tank discharge piping. • The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. • As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. ·The SWPPP will be reviewed monthly to ensure the content is current. • Upon request, contractor shall provide the DOE and City of Sammamish with current SWPPP. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 19 Bethany Corner 3 Pollution Prevention Team Table 7 -Team Information Title Name(sl Certified Erosion and Associated Earth Sciences, Inc. Sediment Control Lead (CESCL) Resident Engineer Jonathan S. Murray, PE Emergency Ecology Howard Zorzi Contact Emergency Permittee/ Mark Seek Owner Contact Non-Emergency Owner Mark Seek Contact Monitoring Personnel Associated Earth Sciences, Inc. Ecology Regional Office Northwest Regional Office City Spill Hotline (8:00 am to 5:00 om) King County Spill Hotline (After Hours) D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 20 Phone Number 425.827.7701 425-827-3063 425-649-7130 206-315-8130 206-315-8130 425.827.7701 425-649-7000 425-295-0500 206-296-8100 Bethany Corner 4 Monitoring and Sampling Requirements Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling 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 • Stormwater sampling data File a blank form under Appendix D. The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. 4.1 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 C160. The name and contact information for the CESCL is provided in Section 3 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. Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 4.2 Stormwater Quality Sampling Runoff will be collected and conveyed to the proposed vault, followed by a StormFilter media filtration system to meet Enhanced Water Quality requirements. Testing will occur as deemed necessary by the CESCL. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 21 Bethany Corner 4.2.1 Turbidity Sampling Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 -Turbidity Sampling Method LJ Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) IX.I Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) ' ' The benchmark for turb1d1ty value 1s 25 nephelometnc turb1d1ty units (NTU) and a transparency less than 33 centimeters. If the discharge's turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1 . Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone the applicable Ecology Region's Environmental Report Tracking System (ERTS) number within 24 hours. • Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 • Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 • Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 • Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 22 Bethany Corner 4. Continue to sample discharges daily until one of the following is true: • Turbidity is 25 NTU (or lower). • Transparency is 33 cm (or greater). • Compliance with the water quality limit for turbidity is achieved. o 1 -5 NTU over background turbidity, if background is less than 50 NTU o 1 % -10% over background turbidity, if background is 50 NTU or greater • The discharge stops or is eliminated. 4.2.2 pH Sampling pH monitoring is required for "Significant concrete work" (i.e., greater than 1000 cubic yards poured or recycled concrete over the life of the project). The use of engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils, pH sampling begins when engineered soils are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO 2 ) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO 2 sparging or dry ice. Method for sampling pH: Table 9 -pH Sampling Method I I pH meter I I pH test kit D Wide ranqe pH indicator paper Not: pH monitoring equipment unknown at this time; to be determined by CESCL D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 23 Bethany Corner 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies 5.1 303(d) Listed Waterbodies Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? r:21 YesD No List the impairment(s): Green River -pH 5.2 TMDL Waterbodies Waste Load Allocation for CWSGP discharges: List and describe BMPs: Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 24 Bethany Corner 6 Reporting and Record Keeping 6.1 Record Keeping 6.1.1 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 • Sample logs 6.1.2 Records Retention Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: • CSWGP • Permit Coverage Letter • SWPPP • Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. 6.1.3 Updating the SWPPP The SWPPP will be modified if: • Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. • There is a change in 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 will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. 6.2 Reporting 6.2.1 Discharge Monitoring Reports Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 25 Bethany Corner monitoring period the DMR will be submitted as required, reporting "No Discharge". The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology's WQWebDMR System. 6.2.2 Notification of Noncompliance If any of the terms and conditions of the pemrit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be immediately notified of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. • Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County • Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County • Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County • Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Include the following information: 1. Your name and / Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date I Time of call 6. Date I Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO, sparging is planned for adjustment of high pH water. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page 26 Bethany Corner Appendix A Site Map D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Alpine Nursery Page A-1 I 111 •I~ ,-1-~ i i ~ I< .-~ ;:; -,.. I I D ~ ~ ~ ~ I , I ~'.'.l ~ I ~ ~ ty/ ~ OCJOCl ~I Ii ,~ ~ .,: ~, fil . ~ ~ ~ "' I v-1 ~' I ! i ~ I s 0 ~ ~ i H ~ ·1 I .~ a ~ d i '~ I w ~ i! !l ~ •• ~ . ;I n a "T ~ ~D ' mi : I ! I ~~ z Ill I w . . ... _ ,_, I • ~' ~ i ~~~'tp~~ ~~ ~ <[ ~ ~ !~ iU ~~ ~ ~~ 1~ j ~ii 0 nh i I ~ in I I I~ i~:~::111111~;1~ •s1I " ~ • I . • w ffi w!cn t-,.. '-Ill .,...,..H -~ . ~ "' 8 ~. r1! Ii!! i ! i I I ! ii I I i u~ >->->->-z I\ f = I• • i ! ! i I I ! . I l"~r~n n, I a.; l::tllD!DCC 0:: ~~1 ·-1 -I is~ ~ I ~I ' ' HI 0 :2 ~ ' 11 i I 1 1 j I I § ! 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'1 ~I llijll 11 -~ '" I'' ~ -~ I i, Appendix B BMP Details D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Alpine Nursery Page B-1 Appendix C Correspondence None at this time. D.R. STRONG Consulting Engineers, Inc. Storm water Pollution Prevention Plan Alpine Nursery Page C-1 Appendix D Site Inspection Form 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 perfomred and documented as outlined below. At a minimum, each inspection report or checklist shall include: Inspection date/times 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: locations of BMPs inspected, locations of BMPs that need maintenance, the reason maintenance is needed, locations of BMPs that failed to operate as designed or intended, and 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. A statement that, in the judgment of the person conducting ihe 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. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page D-1 Alpine Nursery 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. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page D-2 Alpine Nursery Construction Stormwater Site Inspection Form Permit#: Date: Time: Project Name --------- Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if Jess than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): -------------------- Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear D Cloudy D Mist D Rain D Wind D Fog D A. Type of inspection: Weekly D Post Storm Event D Other D B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls § Clearing/Demo/Grading § Concrete pours Vertical Construction/buildings Offsite improvements Site temporary stabilized Infrastructure/storm/roads § Utilities Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions 54 & 55) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to# 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Parameter Method (circle one) Turbidity tube, meter, laboratory pH Paper, kit, meter D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Date: Result Other/Note NTU cm pH Alpine Nursery Page D-3 Construction Stormwater Site Inspection Form D. Check the observed status of all items. Provide "Action Required "details and dates. Element # Inspection 1 Before beginning land disturbing Clearing activities are all clearing limits, natural Limits resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction access is stabilized with Construction quarry spalls or equivalent BMP to Access prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Are flow control measures installed to Control Flow control storm water volumes and Rates velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 All perimeter sediment controls (e.g. Sediment silt fence, wattles, compost socks, Controls berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Storm water runoff from disturbed areas is directed to sediment removal BMP. 5 Have exposed un-worked soils been Stabilize Soils stabilized with effective BMP to prevent erosion and sediment deposition? Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inleti waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan BMPs BMP needs Inspected maintenance yes no n/a Page 0-4 BMP Action required failed (describe in section F) Alpine Nursery Construction Stormwater Site Inspection Form Element # Inspection 6 Has stormwater and ground water Protect been diverted away from slopes and Slopes disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from storm water generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Storm drain inlets made operable Drain Inlets during construction are protected. Are existing storm drains within the influence of the project protected? 8 Have all on-site conveyance channels Stabilize been designed, constructed and Channel and stabilized to prevent erosion from Outlets expected peak fiows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Are waste materials and demolition Control debris handled and disposed of to Pollutants prevent contamination of storm water? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Wheel wash wastewater is handled and disposed of properly. 10 Concrete washout in designated areas. Control No washout or excess concrete on the Dewatering ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan BMPs Inspected yes no n/a Page D-5 BMP needs BMP Action required maintenance failed (describe in section F) Alpine Nursery Construction Stormwater Site Inspection Form Element # Inspection 11 Are all temporary and permanent Maintain erosion and sediment control BMPs BMP maintained to perform as intended? 12 Has the project been phased to the Manage the maximum degree practicable? Project Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? E. Check all areas that have been inspected. v All in place BMPs D All discharge locations All disturbed soils D All material storage areas BMPs Inspected BMP needs BMP Action required yes no n/a maintenance failed (describe in section F) D All concrete wash out areas D All construction entrances/exits D All equipment storage areas D D F. Elements checked "Action Required" (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element Description and location Action Required # Attach additional page if needed Sign the following certification: "I certify that this report is true, accurate, and complete, to the best of my knowledge and belief" Inspected by: Print Title/Qualification of Inspector D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Signature Date Page D-6 Completion Initials Date Alpine Nursery I Appendix E Construction Stormwater General Permit (CSWGP) D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page F-2 Alpine Nursery Appendix F Engineering Calculations Existing Site Hydrology KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the soil type is modeled as "Till" for the Alderwood gravelly sandy loam SCS classification. The entire Site is modeled as "Forest." Results of the KCRTS analysis are included in this section. & Land Use Summary l=,~iiii ,-Area Till Forestl 1.96 acresi i 0.00 acres; Till Pasture! Till Grass! 0.00 acresi Outwash Forest\ 0.00 acres! Outwash Pasture 0.00 acres: Outwash Grassl 0.00 acres Wetlandi 0.00 acres! Impervious! 0.05 acres '----···-··"""" r Total . i 2.00 acres! ---------------- Scale Factor: 1.00 Hourly Reduced Time Series: jpredev Compute Time Series Modify User Input ------File for computed Time Series [.TSF] Flow F.:::-equency Analysis Time Series Fi:e:predev.tsf Project Location:Sea-T2c j 1»1 I I ---Annual ?e2k Flow Rates--------Flow Freqc.er.cy Analys:..s------- Flow Rate Rank Time o:: (CFS) 0 .1._31 2 2/09/81 0.042 7 1/05/02 0.103 3 2/28/03 0.0~2 8 8/26/04 0.061 6 1/05/05 0.103 4 1/18/06 0.091 5 11/24/06 0.176 1 1/09/08 Computed Peaks Peak 18:00 16:00 3:00 2:00 8:00 20:00 4:CO 9:00 --Peaks Rank Return Prob (CFS) Period 0.176 1 100.00 0.131 2 25.00 0.103 3 10.00 0.103 4 0.091 5 0.061 6 O.C42 7 C. c:_2 8 C.161 5.00 3.0C 2.00 1. 30 1.10 so.co 0.990 0. 960 0.900 o.soc C.667 c.soo 0.23: 0.091 0.980 The maximum discharge of the construction stormwater will not exceed 50% of the 2-year predeveloped peak flow rate of 0.061 cfs. Therefore the max discharge from the Site during construction will not exceed 0. 0305 cfs. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Page F-2 Alpine Nursery fl Land Use Summary Are• Till Forest 0.00 acres Till Pasture 0.00 acres TIii Grass 0.68 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.17 acres Toto! 1.85 acres -· ------"·" Scale Factor: 1.00 15-Min Reduced Edit Flow Paths Time Series: lrdin 15 Compute Time Series Modify User Input .. .. . File for computed Time Series (.TSF] Flow Frequency Analysis Time Series File:rdin 15.tsf Project Location:Sea-Tac L=:' ,1.-- 11 I '»I I I ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks Rank Return Prob (CFS) (CFS) Period 0.557 6 8/27/01 18:00 1. 72 1 100.00 0.990 0. 396 8 1/05/02 15:00 1. 20 2 25.00 0. 960 l. 20 2 12/08/02 17:15 0. 778 3 10.00 0.900 0.449 7 8/23/04 14:30 0.690 4 5.00 0.800 0.690 4 11/1 7 /04 5:00 0.668 5 3.00 0.667 0.668 5 10/27 /05 10:45 0.557 6 2.00 0.500 0. 778 3 10/25/06 22:45 0.449 7 1. 30 0.231 1. 72 1 1/09/08 6:30 0. 396 8 1.10 0.091 Computed Peaks l. 55 50.00 0.980 Sediment Trap Facility Sizing The Site will utilize one sediment trap for sediment control. The maximum discharge rate for the site is 0.031 cfs (50% of the 2-year predeveloped peak). The sediment traps will discharge to the collection system on 111'h AVE SE. Below is sizing summary: Sediment Trap basin: 1.85 acres 2-year peak flow rate: 0.557 cfs Required Surface Area: 1,159 s.f. Provided Surface Area: 1,700 s.f. D.R. STRONG Consulting Engineers, Inc. Stormwater Pollution Prevention Plan Alpine Nursery Page F-2 APPENDIX "C" BOND QUANTITY WORKSHEET ©2016 D.R. STRONG Consulting Engineers Inc. Technical Information Report Page 72 Bethany Corner Renton, Washington SITE IMPROVEMENT BOND QUANTITY WORKSHEET ·RentoCITYnOF (f) PROJECT INFORMATION .,. Planning Division / 1055 South Grady Way-6'" Floor/ Renton, WA 98057 (425} 430-7200 Conununity & Econo1nic Develop111ent Date Prepared: [12/14/2016 Prepared by: Name: Jonathan S. Murray, P.E. PE Registration No: 50096 Firm Name: D.R. STRONG Consulting Engineers, Inc. Firm Address: 620 7th Avenue, Kirkland, WA 98033 Phone No. (425) 827-3063 Email Address: jonathan.murray@drstrong.com Project Location and Description Project Name: Bethany Corner CED Plan# (LUA): ##-###### CED Permit# (U): ######## Site Address: 16433 & 16451111th Ave SE Street Intersection: 111th Ave SE and SE 164th St Parcel #(s): 008800-0560, -0570 Abbreviated Legal LOTS 11 AND 12, BLOCK 7, AKER'$ FARMS NO. 6, ACCORDING TO THE Description: PLAT THEREOF RECORDED IN VOLUME 42 OF PtATS, PAGE 15, RECORDS OF KING COUNTY, WASHINGTON SITUATE IN THE COUNT'i' OF KING, STATE OF WASHINGTON. Clearing and Grading Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No: INo I If Yes, Provide Forest Practice Permit#: IN/A I 1 Select the current project status/phase from the following options: For Approval -Preliminary Data Enclosed, pending approval from the City; For Construction -Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout-Final Costs and Quantities Enclosed for Project Close-out Submittal Project Phase 1 [FOR APPROVAL Engineer Stamp Required (alf cost estimates must have original wet stamp and signature) Project Owner Information Project Owner: Mark Seek Phone: (425) 919-4062 Address: 15233 Manion Way NE Duval, WA 98019 Addt'I Project Owner: Mary Nguyn Phone: Address: 9102 SE 41st St Mercer Island, WA 98040 Utility Providers Water Service Provided by: I SOOS CREEK WATER & SEWER Sewer Service Provided by: I SOOS CREEK WATER & SEWER . Page 1 of 1 Unit Prices Updated: 06/14/2016 Version: 06/14/2016 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR EROSION & SEDIMENT CONTROL CED Permit #:######## Unit Description No. Reference# Price Backfill & compaction-embankment ESC-1 $ 6.50 Check dams, 4" minus rock ESC-2 5WOM 5.4.6.3 80.00 Catch Basin Protection ESC-3 35.50 Crushed surfacing 1114" minus ESC-4 W5DOT 9-03.9/3) 95.00 Ditching ESC-5 9.00 Excavation-bulk ESC-6 2.00 Fence, silt ESC-7 5WDM 5.4.3.1 1.50 Fence, Temporary {NGPE) ESC-8 1.50 Geotextile Fabric ESC-9 2.50 Hay Bale Silt Trap ESC-10 a.so Hydroseeding ESC-11 5WOM 5.4.2.4 0.80 Interceptor Swale/ Dike ESC-12 1.00 Jute Mesh ESC-13 5WOM 5.4.2.2 3.50 Level Spreader ESC-14 1.75 Mulch, by hand, straw, 3" deep ESC-15 5WOM 5.4.2.1 2.50 Mulch, by machine, straw, 2' deep ESC-16 5WOM 5.4.2.1 2.00 Piping, temporary, CPP, 6" ESC-17 12.00 Piping, temporary, CPP, 8" ESC-18 14.00 Piping, temporary, CPP, 12" ESC-19 18.00 Plastic covering, 6mm thick, sandbagged ESC-20 5WOM 5.4.2.3 4.00 Rip Rap, machine placed; slopes ESC-21 W500T9-13.1/2) 45.00 Rock Construction Entrance, SO'xlS'xl' ESC-22 5WOM 5.4.4.1 1,800.00 Rock Construction Entrance, lOO'xlS'xl' ESC-23 5WOM 5.4.4.1 ' 3,200.00 Sediment pond riser assembly ESC-24 5WOM 5.4.5.2 2,200.00 Sediment trap, 5' high berm ESC-25 5WOM 5.4.5.1 19.00 Sed. trap, 5' high, riprapped spillway berm section ESC-26 5WOM 5.4.5.1 70.00 Seeding, by hand ESC-27 5WOM 5.4.2.4 1.00 Sodding, 1" deep, level ground ESC-28 5WOM 5.4.2.5 8.00 Sodding, 1" deep, sloped ground ESC-29 5WOM 5.4.2.5 10.00 TESC Supervisor ESC-30 110.00 Water truck, dust control ESC-31 5WOM 5.4.7 140.00 Unit WRITE-IN-ITEMS Reference# Price Sump Pump s 250.00 Unit CY Each Each CY CY CY LF LF SY Each SY LF SY LF SY SY LF LF LF SY CY Each Each Each LF LF SY SY SY HR HR Unit ,Each EROSION/SEDIMENT SUBTOTAL: Page 1 of 1 SALES TAX@ 9.5% EROSION/SEDIMENT TOTAL: Al Quantity Cost 10000 65,000.00 19 1,520.00 11 390.50 965 1,447.50 6500 5,200.00 1000 1,000.00 6500 13,000.00 54 972.00 10 450.00 1 3,200.00 16 1,760.00 16 2,240.00 Quantity Cost 1 250.00 96,430.00 9,160.85 105,590.85 IAI Unit Prices Updated: 06/14/2016 Version: 06/14/2016 CED Permit #:######## Description GENERAL ITEMS Backfill & Compaction-embankment Backfill & Compaction-trench Clear/Remove Brush, by hand (SY) Bollards -fixed Bollards -removable Clearing/Grubbing/Tree Removal Excavation -bulk Excavation -Trench Fencing, cedar, 6' high Fencing, chain link, 4' Fencing, chain link, vinyl coated, 6' high SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Existing Future Public Right-of-Way Improvements IB) IC! No. Unit Price I Unit Quant. Cost Quant. Cost Gl-1 $ 6.00 CY 2990 17,940.00 Gl-2 $ 9.00 CY 115 1,035.00 Gl-3 $ 1.00 SY Gl-4 $ 240.74 Each Gl-5 $ 452.34 Each Gl-6 $ 10,000.00 Acre 0.3 3,000.00 Gl-7 $ 2.00 CY Gl-8 $ 5.00 CY 115 575.00 Gl-9 $ 20.00 LF Gl-10 $ 38.31 LF Gl-11 $ 20.00 LF Fencing, chain link, gate, vinyl coated, 20' Gl-12 $ 1,400.00 Each Fill & compact -common barrow Gl-13 $ 25.00 CY Fill & compact -gravel base Gl-14 $ 27.00 CY Fill & compact -screened topsoil Gl-15 $ 39.00 CY Gabion, 12" deep, stone filled mesh Gl-16 $ 65.00 SY Gabion, 18" deep, stone filled mesh Gi-17 $ 90.00 SY Gabion, 36" deep, stone filled mesh Gl-18 $ 150.00 SY Grading, fine, by hand Gl-19 $ 2.50 SY Grading, fine, with grader Gl-20 $ 2.00 SY Monuments, 3' Long Gi-21 $ 250.00 Each 1 250.00 Sensitive Areas Sign Gl-22 $ 7.00 Each Sodding, 1" deep, sloped ground Gl-23 $ 8.00 SY Surveying, line & grade Gl-24 $ 850.00 Day 2 1,700.00 Surveying, lot location/lines Gl-25 $ 1,800.00 Acre 0.3 540.00 Topsoil Type A (imported) Gl-26 $ 28.50 CY Traffic control crew ( 2 flaggers) Gl-27 $ 120.00 HR Trail, 4" chipped wood Gl-28 $ 8.00 SY Trail, 4" crushed cinder Gl-29 $ 9.00 SY Trail, 4" top course Gl-30 $ 12.00 SY Conduit, 2" Gl-31 $ 5.00 LF Wall, retaining, concrete Gl-32 $ 55.00 SF Wall, rockery Gl-33 $ 15.00 SF I 250.00 I I 24,790.00 I (B) !Cl Page 1 of 3 Private Quantity Remaining Improvements (Bond Reduction) (DI Quant. 6973 470 1.5 3000 470 2 1.5 I IE) Cost Quant. I Cost 41,838.00 4,230.00 15,000.00 6,000.00 2,350.00 1,700.00 2,700.00 n,s1s.oo 1 I (D} IE) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 I SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit #:######## Existing Future Public Right-of-Way Improvements (BJ (C) Description No. Unit Price I Unit Quant. Cost Quant. Cost ROAD IMPROVEMENT/PAVEMENT/SURFACING AC Grinding, 4' wide machine< lOOOsy Rl-1 $ 30.00 SY AC Grinding, 4' wide machine 1000-2000sy Rl-2 $ 16.00 SY AC Grinding, 4' wide machine> 2000sy Rl-3 $ 10.00 SY AC Removal/Disposal Rl-4 $ 35.00 SY Barricade, Type Ill ( Permanent) Rl-5 $ 56.00 LF Guard Rail Rl-6 $ 30.00 LF Curb & Gutte·r, rolled Rl-7 $ 17.00 LF Curb & Gutter, vertical Rl-8 $ 12.50 LF 275 3,437.50 516 6,450.00 Curb and Gutter, demolition and disposal Rl-9 $ 18.00 LF Curb, extruded asphalt Rl-10 $ 5.50 LF Curb, extruded concrete Rl-11 $ 7.00 LF Sawcut, asphalt, 3" depth Rl-12 $ 1.85 LF 425 786.25 Sawcut, concrete, per 1" depth Rl-13 $ 3.00 LF Sealant, asphalt Rl-14 $ 2.00 LF 425 850.00 Shoulder, gravel, 4" thick Rl-15 $ 15.00 SY Sidewalk, 4" thick Rl-16 $ 38.00 SY 152 5,776.00 287 10,906.00 Sidewalk, 4" thick, demolition and disposal Rl-17 $ 32.00 SY Sidewalk, 5" thick Rl-18 $ 41.00 SY Sidewalk, 5" thick, demolition and disposal Rl-19 $ 40.00 SY Sign, Handicap Rl-20 $ 85.00 Each Striping, per stall Rl-21 $ 7.00 Each Striping, thermoplastic, ( for crosswalk) Rl-22 $ 3.00 SF Striping, 4" reflectorized line Rl-23 $ 0.50 LF Additional 2.5" Crushed Surfacing Rl-24 $ 3.60 SY HMA 1/2" Overlay 1.5" Rl-25 $ 14.00 SY HMA 1/2" Overlay 2" Rl-26 $ 18.00 SY 375 6,750.00 HMA Road, 2", 4" rock, First 2500 SY Rl-27 $ 28.00 SY HMA Road, 2", 4" rock, Qty. over 2500SY Rl-28 $ 21.00 SY HMA Road, 4", 6" rock, First 2500 SY Rl-29 $ 45.00 SY 120 5,400.00 685 30,825.00 HMA Road, 4", 6" rock, Qty. over 2500 SY Rl-30 $ 37.00 SY HMA Road, 4", 4.5" ATB Rl-31 $ 38.00 SY Gravel Road, 4" rock, First 2500 SY Rl-32 $ 15.00 SY Gravel Road, 4" rock, Qty. over 2500 SY Rl-33 $ 10.00 SY Thickened Edge Rl-34 $ 8.60 LF I 22,999.75 I I 48,1s1.oo I (BJ !CJ Page2of3 Private Improvements (D) Quant. Cost I (DJ Quantity Remaining {Bond Reduction) (E) Quant. I Cost I (E) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 I SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit #:######## Existing Future Public Right-of-Way Improvements (B) (C) Description No. Unit Price I Unit Quant. I Cost Quant. I Cost PARKING LOT SURFACING No. 2" AC, 2" top course rock & 4" borrow PL-1 $ 21.00 SY 2" AC, 1.5" top course & 2.5" base course PL-2 $ 28.00 SY 4" select borrow PL-3 $ S.00 SY 1.5" top course rock & 2.5" base course PL-4 $ 14.00 SY SUBTOTAL PARKING LOT SURFACING: (B) ICI LANDSCAPING & VEGETATION No. Street Trees LA-1 Median Landscaping LA-2 Right-of-Way Landscaping LA-3 Wetland Landscaping LA-4 -I (B) ICI TRAFFIC & LIGHTING No. Signs TR-1 Street Light System (#of Poles) TR-2 $ 6,000.00 Each 3 18,000.00 s 30,000.00 Traffic Signal TR-3 Traffic Signal Modification TR-4 SUBTOTAL TRAFFIC & LIGHTING: I 1s,ooo.oo I I 30,000.00 I (B) IC) I WRITE-IN-ITEMS I I I I SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL: I 41,249.75 ] I 102,911.00 I SALES TAX@ 9.5% I 3,918.73_] I 9,782.251 STREET AND SITE IMPROVEMENTS TOTAL: I 4S,168.48 I I 112,1s3.2s I (BJ ICJ Page 3 of 3 Private Quantity Remaining Improvements (Bond Reduction} (O) Quant. I I I I IE) Cost Quant. Cost ID) IE) (D) IE) ID) IE) n,s1s.oo I 1,012.11 I so,s3o.n I {DJ {EJ Unit Prices Updated: 06/14/2016 Version: 06/14/2016 CED Permit #:######## Description SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Public Right-of-Way Improvements (B( (C) No. Unit Price Unit Quant. Cost Quant. I Cost Private Improvements ID\ Quant. I Cost DRAINAGE fCPE = Corru.,.ated PoJvethvlene Pine N12 or Enuivalentl For Culvert nrices Avera.,.e of 4' cover was assumed, Assume nerforated PVC is same nrice as solid nine.I Access Road, R/D D-1 $ 26.00 SY 22 572.00 10 260.00 • (CBs include frame and lid) Beehive D-2 $ 90.00 Each Through-curb Inlet Framework D-3 $ 400.00 Each 2 800.00 CB Type I D-4 $ 1,500.00 Each 7 10,500.00 1 1,500.00 CB Type IL D-5 $ 1,750.00 Each CB Type II, 48" diameter D-6 $ 2,300.00 Each 2 4,600.00 for additional depth over 4' D-7 $ 480.00 FT 18 8,640.00 CB Type 11, 54" diameter D-8 $ 2,500.00 Each for additional depth over 4' D-9 $ 495.00 FT CB Type II, 60" diameter D-10 $ 2,800.00 Each for additional depth over 4' D-11 $ 600.00 FT CB Type II, 72" diameter D-12 $ 6,000.00 Each for additional depth over 4' D-13 $ 850.00 FT CB Type II, 96" diameter D-14 $ 14,000.00 Each for additional depth over 4' D-15 $ 925.00 FT Trash Rack, 12" D-16 $ 350.00 Each Trash Rack, 15" D-17 $ 410.00 Each Trash Rack, 18" D-18 $ 480.00 Each Trash Rack, 21" D-19 $ 550.00 Each Cleanout, PVC, 4" 0·20 $ 150.00 Each Cleanout, PVC, 6" D-21 $ 170.00 Each 8 1,360.00 Cleanout, PVC, 8" D-22 $ 200.00 Each Culvert, PVC, 4" (Not allowed in ROW) D-23 $ 10.00 LF Culvert, PVC, 6" (Not allowed in ROW) D-24 $ 13.00 LF 300 3,900.00 Culvert, PVC, 8" (Not allowed in ROW) D-25 $ 15.00 LF Culvert, PVC, 12" (Not allowed in ROW) D-26 $ 23.00 LF Culvert, PVC, 15" (Not allowed in ROW) D-27 $ 35.00 LF Culvert, PVC, 18" (Not allowed in ROW) D-28 $ 41.00 LF Culvert, PVC, 24" (Not allowed in ROW) D-29 $ 56.00 LF Culvert, PVC, 30" {Not allowed in ROW) D-30 $ 78.00 LF Culvert, PVC, 36" {Not allowed in ROW) D-31 $ 130.00 LF Culvert, CMP, 8" D-32 $ 19.00 LF Culvert, CMP, 12" D-33 $ 29.00 LF I 24,312.00 I I 2,300.00 I I s,s20.oo I (B) (C) (D) Pagelof5 u.uant1ty Kemaining (Bond Reduction) IE\ Quant. I Cost (E) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 CED Permit#:######## Description DRAINAGE {Continued) Culvert, CMP, 15" Culvert, CMP, 18" Culvert, CMP, 24" Culvert, CMP, 30" Culvert, CMP, 36" Culvert, CMP, 48" Culvert, CMP, 60" Culvert, CMP, 72" Culvert, Concrete, 8" Culvert, Concrete, 12" Culvert, Concrete, 15" Culvert, Concrete, 18" Culvert, Concrete, 24" Culvert, Concrete, 30" Culvert, Concrete, 36" Culvert, Concrete, 42" Culvert, Concrete, 48" Culvert, CPE, 6" (Not allowed in ROW) Culvert, CPE, 8" (Not allowed in ROW) Culvert, CPE, 12" (Not allowed in ROW) Culvert, CPE, 15" (Not allowed in ROW) Culvert, CPE, 18" (Not allowed in ROW) Culvert, CPE, 24" (Not allowed in ROW) Culvert, CPE, 30" (Not allowed in ROW) Culvert, CPE, 36" (Not allowed in ROW) Culvert, LCPE, 6" Culvert, LCPE, 8" Culvert, LCPE, 12" Culvert, LCPE, 15" Culvert, LCPE, 18" Culvert, LCPE, 24" Culvert, LCPE, 30" Culvert, LCPE, 36" Culvert, LCPE, 48" Culvert, LCPE, 54" Page2of5 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Public Right-of-Way Improvements IBI [C) I No. Unit Price Unit Quant. Cost Quant. Cost D-34 $ 35.00 LF D-35 $ 41.00 LF D-36 $ 56.00 LF D-37 $ 78.00 LF D-38 s 130.00 LF D-39 s 190.00 LF D-40 s 270.00 LF D-41 $ 350.00 LF D-42 $ 42.00 LF D-43 $ 48.00 LF D-44 $ 78.00 LF D-45 $ 48.00 LF D-46 $ 78.00 LF D-47 $ 125.00 LF D-48 s 150.00 LF D-49 $ 175.00 LF D-50 $ 205.00 LF D-51 $ 14.00 LF D-52 $ 16.00 LF D-53 $ 24.00 LF D-54 $ 35.00 LF D-55 $ 41.00 LF D-56 $ 56.00 LF D-57 $ 78.00 LF D-58 $ 130.00 LF D-59 $ 60.00 LF D-60 $ 72.00 LF D-61 $ 84.00 LF 639 53,676.00 156 13,104.00 D-62 s 96.00 LF D-63 $ 108.00 LF D-64 $ 120.00 LF D-65 $ 132.00 LF D-66 $ 144.00 LF D-67 $ 156.00 LF D-68 $ 168.00 LF I s3,676.oo I I u,104.oo I 181 ICI Private Improvements [D) Quant. I Cost I I ID) uuant1ty Kema1ning (Bond Reduction) IE) Quant. I Cost IE) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 CED Permit#:######## Description DRAINAGE fContinuedl Culvert, LCPE, 60" Culvert, LCPE, 72" Culvert, HOPE, 6" Culvert, HOPE, 8" Culvert, HOPE, 12" Culvert, HOPE, 15" Culvert, HOPE, 18" Culvert, HOPE, 24" Culvert, HOPE, 30" Culvert, HOPE, 36" Culvert, HOPE, 48" Culvert, HOPE, 54" Culvert, HOPE, 60" Culvert, HOPE, 72" Pipe, Polypropylene, 6" Pipe, Polypropylene, 8" Pipe, Polypropylene, 12" Pipe, Polypropylene, 15" Pipe, Polypropylene, 18" Pipe, Polypropylene, 24" Pipe, Polypropylene, 30" Pipe, Polypropylene, 36" Pipe, Polypropylene, 48" Pipe, Polypropylene, 54" Pipe, Polypropylene, 60" Pipe, Polypropylene, 72" Culvert, Dl, 6" Culvert, DI, 8" Culvert, Dl, 12" Culvert, DI, 15" Culvert, DI, 18" Culvert, DI, 24" Culvert, Dl, 30" Culvert, DI, 36" Culvert, DI, 48" Culvert, DI, 54" Culvert, DI, 60" Culvert, DI, 72" Pai.;e 3 of 5 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Public Right-of-Way Improvements (B) (C) No. 1 Unit Price I Unit Quant. Cost Quant. Cost 0-69 $ 180.00 LF 0-70 $ 192.00 LF 0-71 $ 42.00 LF 0-72 $ 42.00 Lf 0-73 $ 74.00 Lf D-74 $ 106.00 Lf 0-75 $ 138.00 LF 0-76 $ 221.00 LF 0-77 $ 276.00 Lf D-78 $ 331.00 Lf 0-79 $ 386.00 Lf 0-80 $ 441.00 LF 0-81 $ 496.00 Lf 0-82 $ 551.00 LF 0-83 $ 84.00 LF D-84 $ 89.00 LF 0-85 $ 95.00 Lf 0-86 $ 100.00 LF 0-87 $ 106.00 LF 0-88 $ 111.00 LF 0-89 $ 119.00 LF 0-90 $ 154.00 LF D-91 $ 226.00 LF 0-92 $ 332.0D LF 0-93 $ 439.00 LF 0-94 $ 545.00 LF 0-95 $ 61.00 LF D-96 $ 84.00 LF 0-97 $ 106.00 LF 0-98 $ 129.00 LF 0-99 $ 152.00 LF 0-100 $ 175.00 LF 0-101 $ 198.00 LF 0-102 $ 220.00 LF 0-103 $ 243.00 Lf 0-104 $ 266.00 LF 0-105 s 289.00 LF 0-106 s 311.00 LF I I ·-· (BJ (C) Private Improvements ID) Quant. Cost I I (D) Quantity Remaining (Bond Reduction) (E) Quant. Cost (E) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit#:######## Existing Future Puo1ic Right-of-Way Improvements (Bl (C) Description No. Unit Price I Unit Quant. Cost Quant. Cost SoecialTV Draina2e Items Ditching SD-1 $ 9.SO CY Flow Dispersal Trench (1,436 base+) SD-3 $ 28.00 Lf French Drain (3' depth) SD-4 $ 26.00 Lf Geotextile, laid in trench, polypropylene SD-5 $ 3.00 SY Mid-tank Access Riser, 48" dia, 6' deep SD-6 $ 2,000.00 Each Pond Overflow Spillway SD-7 $ 16.00 SY Restrictor/Oil Separator, 12" SD-8 $ 1,150.00 Each Restrictor/Oil Separator, 15" SD-9 $ 1,350.00 Each Restrictor/Oil Separator, 18" SD-10 $ 1,700.00 Each Riprap, placed SD-11 $ 42.00 CY Tank End Reducer (36" diameter} S0-12 $ 1,200.00 Each Infiltration pond testing SD-13 $ 125.00 HR Permeable Pavement SD-14 Permeable Concrete Sidewalk SD-15 Culvert, Box ft X ft SD-16 SUBTOTAL SPECIALTY DRAINAGE ITEMS: {BJ (CJ STORMWATER FACILITIES flnclude Flow Control and Water nualitv Facili v Summarv Sheet and Sketchl Detention Pond Sf-1 Each Detention Tank SF-2 Each Detention Vault Sf-3 Each Infiltration Pond Sf-4 Each Infiltration Tank Sf-5 Each Infiltration Vault SF-6 Each Infiltration Trenches Sf-7 Each Basic Biofiltration Swale SF-8 Each Wet Biofiltration Swale Sf-9 Each Wetpond Sf-10 Each Wetvault Sf-11 $ 160,500.00 Each Sand Filter SF-12 Each Sand Filter Vault Sf-13 Each Linear Sand Filter Sf-14 Each Stormfilter Sf-15 Each Rain Garden Sf-16 Each (B) (C) Page 4 of 5 Private Improvements (D) Quant. Cost (DI 1 160,500.00 I 160,soo.oo I (OI u_uant1ty J1:ema1n1ng (Bond Reduction) fE\ Quant. Cost fE( I (E) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit#:######## Existing Future Pubic Right-of-Way Improvements (B) (C) Description No. I Unit Price I Unit Quant. Cost Quant. Cost WRITE-IN-ITEMS Wl-1 Wl-2 Wl-3 Wl-4 Wl-5 Wl-6 Wl-7 Wl-8 Wl-9 Wl-10 Wl-11 Wl-12 Wl-13 W!-14 Wl-15 SUBTOTAL WRITE-IN ITEMS: I DRAINAGE AND STORMWATER FACILITIES SUBTOTAL: I n,9ss.oo I I 1s,404.oo I SALES TAX@ 9.S% I 7,408.86] I 1,463.38 I DRAINAGE AND STORMWATER FACILITIES TOTAL: I ss,396.86 I I 16,s61.3s I {B) {C) Pai;:e 5 of 5 Private Improvements (DI Quant. Cost I I I 166,020.00 I I 1s,n1.9o I I 1s1, 191.90 I )DI -----O:uant1tyHemainmg (Bond Reduction) (E) Quant. I Cost IE) Unit Prices Updated: 06/14/2016 Version: 06/14/2016 SITE IMPROVEMENT BOND QUANTITY WORKSHEET RentoCITYnOF e BOND CALCULATIONS Planning Division /1055 South Grady Way-6th Floor/ Renton, WA 98057 (425) 430-7200 Date· 12/14/2016 Prepared by: Name: Jonathan S. Murray, P.E. Project Name: PE Registration No: 50096 CED Plan# (LUA): Firm Name: D.R. STRONG Consulting Engineers, Inc. CED Permit# (U); Firm Address: 620 7th Avenue, Kirkland, WA 98033 Site Address: Phone No. (425) 827-3063 Parcel #(s): Email Address: jonatha n.mu rray@drstrong.com Project Phase: CONSTRUCTION BOND AMOUNT •r• (prior to permit issuance) Site Restoration/Erosion Sediment Control Subtotal (al s 105,590.85 I Existing Right-of-Way Improvements Subtotal (b) s 45,168.481 Future Public Improvements Subtotal [cl s 112,753.251 Stormwater & Drainage Facilities Subtotal (di s 284,056.141 Bond Reduction (Quantity Remaining) 2 (e) Is -I Site Restoration p (a) x 150% is 158,386.28 I Civil Construction Permit R ((b)+(c)+{d}) X 150'% is 662,966.79 I Maintenance Bond Bond Reduction 2 s Is I -(e)x 150% Construction Permit Bond Amount 3 T is 821,353.07 I (P+R-S) Minimum Bond Amount is $10,000.00 1 Estimate Only -May in11ol11e multiple and variable components, which will be established on an individual basis by Development Engineering. Community & Economic Development Project Information Bethany Corner ##-###### ######## 16433 & 16451111th Ave SE 008800-0560, -0570 FOR APPROVAL MAINTENANCE BOND., .. {after final acceptance of construction) (al s 105,590.85 [bl s 45,168-48 [cl s 112,753.25 [di s 284,056-14 (e) Is -I EST 1 is 88,395_57 I (lb)+ J<) + (di) X 20% 2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will cover all remaining items to be constructed. :i Required Bond Amounts are subJect to review and modification by Development Engineering. ""Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton. *"' Note: All prices include labor, equipment, materials, overhead and profit. D~.-. .. 1 nf 1 Unit Prices Updated: 06/14/2016 11 .. ....-in~. ri,:;/1 ~ /?{11,::