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Home My WebLink AboutLUA16-000967_Misc• F civil & structural ENGINEERING 250 4th Ave S Ste 200 Edmonds, WA 98020 Phone: (425) 778-8500 Fax: (425) 778-5536 engineering & planning TECHNICAL INFORMATION REPORT Aberdeen Ave Subdivision 1824 Aberdeen Ave NE Renton, WA 98056 02/16/2017 CG Project No. 16037 .20 Table of Contents TIR Section I -Project Overview TIR Section II -Conditions and Requirements Summary TIR Section Ill -Off Site Analysis TIR Section IV -Flow Control and Water Quality Facility Analysis and Design TIR Section V-Conveyance System Analysis and Design TIR Section VI -Special Reports and Studies TIR Section VII -Other Permits TIR Section VIII -CSWPPP Analysis and Design TIR Section IX -Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section X -Operation and Maintenance Manual CT ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.ssoo I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report TIR Section I Summary Narrative TIR Section I -Project Overview List of Figures: 1. TIR Worksheet 2. Site Location 3. Aerial Photograph Map February 16, 2017 Section I, Page 1 4. Site Drainage, Drainage Basins, Sub-basins, and Site Characteristics 5. Soils The project proposes to subdivide a single 16,161 sf parcel in the R-8 zone into 2 individual single-family lots. The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The project will add more than 2,000 sf of impervious surfaces and will therefore address Full Drainage requirements from the 2017 Renton Surface Water Design Manual (RSWDM). Lots 1 and 2 will be developed in the future. Stormwater requirements are addressed as part of this project for the driveway tract and for the future lots. Address: 1824 Aberdeen Ave NE, Renton, WA 98056 Tax Parcel Number: 334390-1606 The existing lot will be divided as follows: Proposed Short Plat Coverage Lot 1: 5,677 sf (0.130 ac) Lot 2: 7,903 sf (0.181 ac) Tract: 2,581 sf {0.059 acl Total: 16,128 sf (0.370 ac) Flow Control per Core Requirement #3 must be evaluated for this site because over 5,000 sf of new plus replaced impervious surface will be created. The project falls within the City's Flow Control Duration Standard (Forested Conditions). However, the project is exempt from the facility requirement because there is no more than a 0.15-cfs difference (when modeled using 15-minute time steps) in the 100-year peak flow. Please see Section IV for the Western Washington Hydrology Model report and assumptions. Flow Control Best Management Practices (BMPs) must be addressed per Core Requirement #9 to mitigate stormwater runoff impacts because the site adds and/or replaces more than 2,000 square feet of impervious surface. Flow Control BMPs were evaluated for the access/utility tract per Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement BMP Requirements) and for the individual lots per Section 1.2.9.2.1 "Small Lot BMP Requirements." A single infiltration trench is proposed to meet the requirements for the access/utility tract and for both lots. Please see Section IV for the infiltration trench sizing and assumptions. CT? ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 42S.778.8soo I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Figure 1-1: Technical Information Report {TIR) Worksheet See attached pages. cm ENGINEERING February 16, 2017 Section I, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425.778.5536 www.cgengineering.com KIN(i COlJKTY, WASH!KGTON, SURFACE WATER DESIGN MAKUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner Prime Metropolis Properties, Inc. Phone 925.377.8882 Address 950 Taraval St. San Francisco, CA 94116 Project Engineer Jared Underbrink Company CG Engineering Phone 425.778.8500 Part 3 TYPE OF PERMIT APPLICATION D Landuse (e.g.,Subdivision / Short Subd. I UPD) D Building (e.g.,M/F /Commercial/ SFR) D Clearing and Grading D Right-of-Way Use fiJ Other Land Use Permit Master Application Part 5 PLAN AND REPORT INFORMATION Technical Information Report 0 Full Type of Drainage Review D Targeted (check one): D Simplified D Large Project Date (include revision D Directed dates): 02/16/17 Date of Final: Part 6 SWDM ADJUSTMENT APPROVALS Part 2 PROJECT LOCATION AND DESCRIPTION Project Name Aberdeen Subdivision DPER Permit# ---------- Location Township _2~3 ____ _ Range 5 Section __ 5 _____ _ Site Address 1824 Aberdeen Ave NE Renton, WA 98056 Part 4 OTHER REVIEWS AND PERMITS D DFW HPA D Shoreline D COE404 Management D Structural D DOE Dam Safety RockeryNaulU __ D FEMA Floodplain D ESA Section 7 D COE Wetlands D Other Site Improvement Plan (Engr. Plans) 0 Plan Type (check Full one): D Modified D Simplified Date (include revision dates): Date of Final: Type (circle one): Standard / Experimental / Blanket Description: (include conditions in TIR Section 2) Approved Adjustment No. Date of Approval: 2016 Surface \Vater Design Manual I 4/24/2016 I I ' ' KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes;@ Describe: Start Date: Completion Date: Re: KCSWDM Adjustment No_ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan:----------------------------- Special District Overlays: __________________________ _ Drainage Basin: East Lake Washington (per King County iMap) Stormwater Requirements: The site falls within the City of Renton's Flow Control Duration Standard Part 9 ONSITE AND ADJACENT SENSITIVE AREAS D River/Stream ---------- D Lake D Wetlands __________ _ D Closed Depression ________ _ D Floodplain ------------ D other ------------- Part 10 SOILS Soil Type Slopes Indianola Loamy Sand 5-15% D High Groundwater Table (within 5 feet) D Other D Additional Sheets Attached 2016 Surface Water Design Manual 2 D Steep Slope ----------- D Erosion Hazard ---------- D Landslide Hazard ---------- D Coal Mine Hazard---------- 0 Seismic Hazard _________ _ D Habitat Protection ---------- [) Zone 2 Aquifer Protection Area Erosion Potential D Sole Source Aquifer D Seeps/Springs 4/24/2016 I Kl"G COUNTY, WASHINGTON, SURfACE WATER DESIGN \1ANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION/ SITE CONSTRAINT D Core 2 -Olfsite Analysis D Sensitive/Critical Areas D SEPA D LID Infeasibility D Other D D Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: Total Site (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: 1 Olfsite Analysis Level: Ci) 2 I 3 dated O 1 /20/16 Flow Control (include facility Level: 1 Q) 3 or Exemption Number 2 summary sheet) Flow Control BMPs Infiltration Trench Conveyance System Spill containment located at: Erosion and Sediment Control / CSWPP/CESCL/ESC Site Supervisor: Construction Stormwater Pollution Prevention Contact Phone: After Hours Phone: Maintenance and Operation Responsibility (circle one): ~/ Public If Private, Maintenance Log Required: Yes@ Financial Guarantees and Provided: Yes@ Liability Water Quality (include facility Type (circle one)~ Sens, Lake / Enhanced Basic / Bog summary sheet) or Exemption No. Surface Area Exemption Landscape Management Plan: Yes@ Special Requirements (as applicable): Area Specific Drainage Type: CDA I SDO I MDP I BP I LMP / Shared Fae,/~ Requirements Name: Floodplain/Floodway Delineation Type (circle one): Major / Minor I Exemption I <t§v 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: 2016 Surface Water Design Manual 3 4/24/2016 KING COUNTY, WASIIINGTO", SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Source Control Describe land use: (commercial I industrial land use) Describe any structural controls: Oil Control High-use Site: Yes 1(tlg) Treatment BMP: Maintenance Agreement: Yes i@ with whom? - Other Drainage Structures Describe: -- Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION [I Clearing Limits 0 Stabilize exposed surfaces CEJ Cover Measures @ Remove and restore Temporary ESC Facilities CiJ Perimeter Protection Iii Clean and remove all silt and debris, ensure [I Traffic Area Stabilization operation of Permanent Facilities, restore [I Sediment Retention operation of Flow Control BMP Facilities as necessary Iii Surface Water Collection Iii Flag limits of SAO and open space preservation D Dewatering Control -N/A areas [I Dust Control D Other [) Flow Control [I Protection of Flow Control BMP Facilities (existing and proposed) ~ Maintain BMPs / Manage Project Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description D Detention D Vegetated Flowpath D Infiltration D Wetpool D Regional Facility [I Filtration Stormfilter (Basic WQ) D Shared Facility D Oil Control 0 Flow Control BMPs Infiltration Trench D Spill Control D Other D Flow Control BMPs D Other 2016 Surface Water Design Manual 4 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS D Drainage Easement D Cast in Place Vault !:El Covenant D Retaining Wall D Native Growth Protection Covenant D Rockery > 4' High 0 Tract 0 Structural on Steep Slope D Other 0 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 a he attached Technical Information Report. To the best of my knowled the informatio rovi ere is accurate. 'Z 2( Signed/Date 2016 Surface Water Design Manual 4/24120[6 5 Aberdeen Ave Subdivision 16037.20 Technical Information Report .·.'._ Y,,:7_... ·,· :L ·~- 'J .1•'. •. "'.';• , i :, ~ : r ; ,, .-,, -·~ 'z· 1· Gene Coulon Memorial Beach Park a r-i[" .·-.,I ~/[ ,. T '" ,. ::t"• May Creek Park '1a242mNn Avenue Northeast @ The Landing " ., Fry's Electronics ~- ' ' ,-.,i ·-:-•-·--,· Figure 1-2: Site Location CT ENGINEERING ~- @ t,F :'=:'.I, ~-- February 16, 2017 Section I, Page 3 ,_':-,.;1, = 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Tec hn ica l Information Report • ENGINEERING Fi gure 1-3 : Aerial Photograph February 16, 20 17 Section I, Page 4 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengi neering.com Aberdee n Ave Su bd ivision 16037 .20 Techn ica l Information Report ake 1nQton • ENGINEERING D rainage basin : East La k e Washington -Renton Feb ru ary 16, 20 17 Sec tion I, Page 5 \', ate, ,I ed rame: Cedar Ri ver / Lake Wa shington 211h &t • \'JRIA rumber: 8 WRIA name : Cedar-Sammamish r.E 16th St NE 1 2th $1 ~ "' ,: t' ~ \ ~ I ,1,~ lDrhl S1 g 0 ~ ljr 9rt, st ! % /Jf 7th st "' Highland s P.ark Re nton Figure 1-4: Drainage Basin Map ; INE 4t h St 3 ~ 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 4 25.778 .8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subd ivis ion 16037.20 Techn ical Information Report Figure 1-5 : Soil s February 16, 2017 Sect ion I, Page 6 Underlying soi ls were determ i ned usin g th e Natural Resources Conservation Serv i ce soi l survey tool. Th e site conta in s I ndianola loamy sand, 5 to 15%, corresponding t o hydro logic so i l group "A." A geotechnica l report w ith a r ecommended infiltration rate is a lso prov id ed in Sect ion VI. See attached p ages. + ENGINEERING 250 4th Avenue South, Su ite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com • . . • • • • . . "' ....... • • • ... ' ...... • I ..... .. I ..... .1• I ..... .... . .. • I I I ---... , -- I - ,, , -·~:},"~~1 ·!' ,:::·:~{!?·:::,: 9 .. .-.. t , J" ... $ • ,.. J .-'' i\ -·1. ~· ....... '.·4·~-:.·!~).~. -~a --------SRI' • • --.. ~ -- -)> ]--_ '1 D" l . __ .,. ff> :i1' f .., Q. ff> ff> ' :I )> '>- L ~ w... .. _,· -. • -z -ff> --;-- .[k' .. -., . j : -------------· ---·-· - M -I . . • • ~· . . I I • I ,t• I ,.,., .t• I .... ,I' I ····:· .... •II •II ... ~ r. • . ... ... r. •. : -I I I I ~ I I ... :.••• ., II ... • ..... ... C\:Z• I .... ... .. I Cl::• .. -• .. • • . • • . • . . ...... • . . . . • Soil Map-King County Area, Washington (Aberdeen Ave Subdivision) MAP LEGEND Area of Interest (AOI) D Soils D -• Area of Interest (AOI) Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features UJ Blowout 181 Borrow Pit )IX Clay Spot 0 Closed Depression X Gravel Pit Gravelly Spot 0 Landfill A. Lava Flow .,., Marsh or swamp 'l!.' Mine or Quarry @ Miscellaneous Water 0 Perennial Water V Rock Outcrop + Saline Spot Sandy Spot .... Severely Eroded Spot * Sinkhole j:, Slide or Slip Id Sadie Spot USDA Natural Resources illiii Conservation Service 13 Spoil Area 0 Stony Spot ro Very Stony Spot '{? Wet Spot 6 Other .. Special Line Features Water Features Streams and Canals Transportation +++ Rails -,,...,,..,.. Interstate Highways US Routes Major Roads Local Roads Background • Aerial Photography Web Soil Survey National Cooperative Soil Survey MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1 :24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection. should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Survey Area Data: King County Area, Washington Version 11, Sep 14, 2015 Soil map units are labeled (as space allows) for map scales 1 :50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013---0ct 6. 2013 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 11/7/2016 Page 2 of 3 Soil Map-King County Area, Washington Map Unit Legend Map Unit Symbol lnC Totals for Area of Interest Natural Resources Conservation Service King County Area, Washington (WA633) Map Unit Name I Acres in AOI Indianola loamy sand. 5 to 15 I percent slopes -------- Web Soil Survey National Cooperative Soil Survey 0.8 --~- 0.8 Aberdeen Ave Subdivision Percent of AOI 100.0% 100.0% 11,7/2016 Page 3 of 3 Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section II, Page 1 TIR Section II -Conditions and Requirements Summary TIR Section II Summary Core Requirements The proposed project will comply with the 2017 Renton Surface Water Design Manual (RSWDM). The project is being submitted for a Full Drainage Review because it proposes to add and/or replace over 2,000 square feet of impervious area. The project must comply with all 9 Core Requirements and all 6 Special Requirements. Therefore, the following conditions are required as specified by the RSWDM. Core Requirements Core Requirement #1: Discharge at the Natural Location: Discharge will remain at the natural location and will flow from east to west. There is a public stormwater system in Aberdeen Ave NE that the site will connect into. Core Requirement #2: Offsite Analysis: Compliance with this requirement is indicated in Section Ill. Core Requirement #3: Flow Control: The site is within a Conservation Flow Control Area. However, the site is exempt from the flow facility requirement per Exception #2 of Section 1.2.3.1.B of the 2016 KCSWDM. Core Requirement #4: Conveyance System: New pipe systems shall 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. Core Requirement #5: Erosion & Sediment Control: A Construction Stormwater Pollution Prevention Plan (CSWPPP) and narrative has been prepared. See Section VIII. Core Requirement #6: Maintenance & Operations: Maintenance requirements are addressed in Section X for the flow control BMP. Core Requirement #7: Financial Guarantees & Liabilities: The project may be required to execute to the City a construction bond prior to a permit and a maintenance bond prior to acceptance. Core Requirement #8: Water Quality: Less than 5,000 square feet of new plus replaced pollution generating impervious surface and less than% acres of new pollution generating pervious surface are proposed. However, basic water quality treatment is required prior to infiltration for new plus replaced PGIS areas per Special Requirement #6: Aquifer Protection Area. Core Requirement #9: Flow Control BMPs: This is discussed in Section IV. An infiltration trench is proposed to meet the flow control BMP requirement of this project. It was sized to fully infiltrate runoff from the assumed roof areas of Lots 1 and 2, and from the proposed road surface of the access/utility tract. CT ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I I. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Special Requirements Special Requirement #1: Other Adopted Requirements: Not applicable. Special Requirement #2: Flood Hazard Area Delineation: Not applicable. Special Requirement #3: Flood Protection Facilities: Not applicable. February 16, 2017 Section II, Page 2 Special Requirement #4: Source Control: Permanent and temporary source Controls are discussed in Section 8 of this report. Special Requirement #5: Oil Control: Not applicable. Special Requirement #6: Aquifer Protection Area: The site is in Zone 2 of the Aquifer Protection Area. The project proposes an infiltration trench to meet Core Requirement #9 and will therefore require water quality treatment prior to infiltration as specified in Core Requirement #8 and Special Requirement #5 OR demonstrate that the soil beneath the facility has properties that reduce the risk of groundwater contamination from typical stormwater runoff. This is addressed in Section IV. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report TIR Section Ill Summary Narrative TIR Section Ill -Off Site Analysis February 16, 2017 Section Ill, Page 3 The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The slope across the lot is downstream from east to west at an average of 4%. Adjacent lots contain single family residences. Task 1: Study Area Definition and Maps The study area is defined as the project site and the area one mile downstream (minimum flow path distance) from the proposed discharge location for the purposes of Task 2, and is defined as the project site and a minimum of one-quarter mile downstream from the proposed discharge location for the purposes of Tasks 3, 4, and 5. The drainage basin map can be found in Figure 4 of Section 1. The site is within the East Lake Washington drainage basin. Task 2: Resource Review Drainage and water quality problems and complaints were investigated using the King County iMap website. None were found within the range of the required downstream analysis. The site does not appear to contain nor is adjacent to any environmentally sensitive areas. Task 3: Field Inspection A site visit was done the morning of 01/20/2016. There did not appear to be any existing drainage issues. There is an 18" public storm main on the western frontage of Aberdeen Ave NE. cm ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425.778.5536 www.cgengineering.com Aberdeen Ave Subd iv ision 16037.20 Technical I nfor mation Report Figure 111-1 View of Aberdeen Ave NE looking south . Figure 111-2 View of site (on left) looking east. • ENGINEERING February 16, 2017 Sec tion Ill, Page 4 250 4th Avenue Sou t h, Suite 200 Edmonds, WA 98020 ph . 425.778 .8500 I t. 425.778.5536 www.cgengineeri ng .com Abe rd een Ave Subd ivision 16037.20 Te chnical Inform at ion Repo rt February 16, 2017 Sect ion I ll, Pa ge 5 ------ Figure 111 -3 View of Aberdeen Ave NE looking north. Figure 111-4 View from ba ck of si te looking west. 4 ENGINEERING 250 4th Av en ue South, Su i te 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengi neeri ng.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Task 4: Drainage System Description and Problem Descriptions February 16, 2017 Section Ill, Page 6 No drainage problems are expected. The existing conveyances adjacent to the site include an 18" public storm main on the western frontage of Aberdeen Ave NE. Site runoff is expected to flow in the existing condition from east to west and connect into this system. Task 5: Mitigation of Existing or Potential Problems No existing drainage problems were discovered. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section V, Page 1 TIR Section V -Conveyance System Analysis and Design TIR Section V Summary: Narrative Per Core Requirement #4, new pipe systems shall be designed with sufficient capacity to convey and contain the 25-year peak flow. Conveyance capacity shall be demonstrated using the methods in Chapter 4 of the KCSWDM. Verification of capacity and performance must be provided for each element of the conveyance system. The analysis must show design velocities and flows for all drainage facilities within the development, as well as those offsite that are affected by the development. The conveyance system will consist of 6" PVC pipes for roof and driveway runoff and a 6" ductile iron pipe as the overflow from the infiltration trench. The 25-year peak flow for the total runoff from the assumed impervious areas runoff prior to infiltration was calculated per WWHM and found to be 0.145 cfs. The conveyance capacity of a 6" ductile iron pipe with a minimum 1% slope is 0.56 cfs. Therefore, a 6" ductile iron pipe is sufficient for the design event. See the conveyance capacity calculation on the following page. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Rational Method -De.-eloped Conditions for: Aberdeen Ate Subdhision Manning's Equation: Q = (1.49 )R'i' S 1/2 n n= 0.014 Connrrance Canadtv 4-inclt 6-inclt S-inclt 10-inclt Slope [It/It) 0.005 0.13 037 0.81 1.44 0.010 0.18 o.52 1.14 2.04 0.015 0.22 0.64 1.40 2.50 0.020 0.25 0.74 1.61 2.88 0.025 0.28 0.82 I.SO 3.23 0.030 0.31 0.90 1.97 3.53 0.035 0.33 0.98 2.13 3.82 0.040 035 1.04 228 4.08 0.045 038 1.11 2.42 433 0.050 0.40 1.17 2-55 4.56 0.055 0.42 1.22 2.67 4.78 0.860 0.43 1.28 2.79 5.00 0.065 0.45 133 2.91 5.20 0.070 0.47 us 3.02 5.40 0.075 0.48 1.43 3.12 5.59 0.880 0.50 1.48 3.22 5.77 0.085 0.52 l_j2 331 5.95 0.090 0.53 1.56 3.42 6.12 0.095 0.55 1.61 3.51 6.29 0.100 0.56 1.65 3.61 6.45 ~ ~ Convevance Caoarnv --<>- ENGINEERING 250 4th A,,._ South Suite 200 Edmoodo, WA 98020 Aberdeen Ave Subdivision ENGINEERING 12-inch 234 332 4.06 4.69 5.14 5.74 620 6.63 7.03 7.41 7.7S s .. 12 8.45 8.77 9.08 9.38 9.67 9.95 10.22 10.48 .,. """ Seu ... ,., VD N.T.S. '16037 .20 February 16, 2017 Section V, Page 2 ,,,., 2,112017 ,,,., ......... 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section IV, Page 1 TIR Section IV -Flow Control and Water Quality Facility Analysis and Design TIR Section IV Summary: Narrative PART A: Existing Site Hydrology PART B: Developed Site Hydrology PART C: Performance Standards PART D: Flow Contra! System PART E: Water Quality System WWHM2012 Report PART A: EXISTING SITE HYDROLOGY The 2012 Western Washington Hydrology Model (WWHM) was used to model flow control. Per the City of Renton's Flow Control Application Map (Reference 11-A in the RSWDM), the site is within the Flow Control Duration Standard (Forested Condition). The predeveloped land coverage is as follows: Pervious Areas Forest, Flat, A/B: Total: PART B: DEVELOPED SITE HYDROLOGY 16,128 sf (0.370 ac) 16,128 sf (0.370 ac) In the proposed condition, the existing lot will be subdivided into 2 lots and existing structures will be demolished. Impervious areas were assumed for the proposed lots according to Section 3.2 of the RSWDM since Lot 1 and Lot 2 will be developed in the future. Per Section 3.2, the assumed impervious coverage "shall not be less than 4,000 sf per lot or the maximum impervious coverage permitted by code Table 3.2.2.C, whichever is less." The maximum impervious coverage allowed per code for the zoning (R-8) is 65%, or 3,689 sf and 5,135 sf for Lot 1 and Lot 2, respectively. The assumed impervious coverage shall be 65% and the maximum building coverage shall be 50% for the purposes of this hydrology model. The assumed developed lot coverage is as follows: Lot 1 Developed Lot Coverage Landscaping, Flat, A/B: Roof, Flat: Driveway/Walkways. Flat: Total: C5 ENGINEERING 1,988 sf (0.045 ac) 2,838 sf (0.065 ac) 851 sf (0.020 ac) 5,677 sf (0.130 ac) 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8soo I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Lot 2 Developed Lot Coverage Landscaping, Flat, A/B: Roof, Flat: Driveway/Walkways, Flat. A/B: Total: Tract Developed Lot Coverage Driveway, Flat. A/B: Total: 2,768 sf (0.063 ac) 3,951 sf (0.091 ac) 1,184 sf (0.027 ac) 7,903 sf (0.181 ac) 2,581 sf (0.059 ac) 2,581 sf (0.059 ac) February 16, 2017 Section IV, Page 2 The proposed Flow Control BMP is an Infiltration Trench per Section 5.2 of the 2016 KCSWDM. An infiltration design rate of 7.35 in/hr was determined for the site (see Section VI for the geotechnical report). The trench was sized to be 80'x5'x2' deep and will be sited in the access/utility tract. Surface water will be directed from the roofs of Lots 1 and 2, and from the access/utility tract. PART C: PERFORMANCE STANDARDS 1. Area-Specific Flow Control Facility standard: The site is within the City of Renton's Flow Control Duration Standard (Forested Conditions). 2. Flow Control BMPs: Flow Control BMP Implementation requirements were determined from Section 1.2.9.3.1 "Small Subdivision and Urban Subdivision Projects BMP Requirements." BMPs for plat infrastructure improvements (driveway tract) were evaluated per Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement Project BMP Requirements." BMPs for the future development of the two individual lots were evaluated per Section 1.2.9.2.1 "Small Lot BMP Requirements." 3. Conveyance System Capacity Standards: New pipe systems shall 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. 4. Water Quality Standard: Storm water from pollution-generating impervious areas will be treated to meet Basic Water Quality prior to infiltration because the site is located in a Zone 2 Aquifer Protection Area. PART D: FLOW CONTROL SYSTEM An infiltration trench is proposed to meet the flow control BMP requirement of this project. The trench will be 80' x 5' x 2' deep and will be sited within the access/utility tract. The design infiltration rate used was 7.35 in/hr per the geotechnical report found in Section VI. It was sized to fully infiltrate runoff from the assumed roof areas of Lots 1 and 2, and from the proposed road surface of the access/utility tract. BMPs must be implemented for 10% of the site/lot for sites/lots up to 11,000 sf per Section 1.2.9.2.1 "Small Lot BMP Requirements." The assumed roof area is 50% of each lot (see Part B), and should therefore meet this requirement. Runoff from all of the impervious surfaces of the access/utility tract cm ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section IV, Page 3 will be infiltrated per the requirement that all target surfaces must be mitigated to the maximum extent feasible from the list in Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement Projects BMP Requirements." The project is exempt from the facility requirement of Core Requirement #3: Flow Control per Exception #2 of Section 1.2.3.1.B of the 2016 KCSWDM because the 100-year peak flow is no more than 0.15 cfs (when modeled using 15-minute time steps). Please see the WWHM summary. The model includes the infiltration trench. PART E: WATER QUALITY SYSTEM A water quality system meeting Basic Water Quality was sized to treat runoff from pollution generating impervious surfaces prior to infiltration because the site is in a Zone 2 Aquifer Protection Area. A Stormfilter by Contech was sized based on the following information: Total drainage area: 0.215 ac (not including roofs) Impervious Drainage Area: 0.106 ac Application (Residential? Commercial? Roadway?): Residential WQ Flow (15 minute offline): 0.0094 cfs WQ Flow (15 minute online): 0.017 cfs Bypass Flow: 0.114 cfs (100-year peak flow rate) Rim: 298.0 Outlet #1: 294.0 (to trench) 6" ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT General Model Information Project Name: Aberdeen Ave 02.02.17 Site Name: Aberdeen Ave Short Plat Site Address: 1824 Aberdeen Ave NE City: Renton Report Date: 2/13/2017 Gage: Seatac Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.00 Version: 2014/01/22 POC Thresholds Low Flow Threshold for POC 1: High Flow Threshold for POC1: Aberdeen Ave 02.02.17 50 Percent of the 2 Year 50 Year 2/13/2017 3:50:26 PM Page 2 Landuse Basin Data Predeveloped Land Use Site Bypass: No Groundwater: No Pervious Land Use Acres AB, Forest, Flat 0.37 Pervious Total 0.37 Impervious Land Use Acres Impervious Total 0 Basin Total 0.37 Element Flows To: Surface lnterflow Aberdeen Ave 02.02.17 Groundwater 2/13/2017 3:50:26 PM Page 3 Mitigated Land Use Impervious Areas Bypass: No GroundWater: No Pervious Land Use Acres Pervious Total 0 Impervious Land Use Acres ROOF TOPS FLAT 0.156 DRIVEWAYS FLAT 0.106 Impervious Total 0.262 Basin Total 0.262 Element Flows To: Surface lnterflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 Aberdeen Ave 02.02 17 2/13/2017 3:50:26 PM Page4 Lawn Bypass: Yes GroundWater: No Pervious Land Use Acres A B, Lawn, Flat 0.108 Pervious Total 0.108 Impervious Land Use Acres Impervious Total 0 Basin Total 0.108 Element Flows To: Surface lnterflow Groundwater Aberdeen Ave 02 02.17 2/13/2017 3:50:26 PM Page 5 Routing Elements Predeveloped Routing Aberdeen Ave 02.02.17 2/13/2017 3:50:26 PM Page 6 Mitigated Routing Gravel Trench Bed 1 Bottom Length: Bottom Width: Trench bottom slope 1: Trench Left side slope O: Trench right side slope 2: Material thickness of first layer: Pour Space of material for first layer: Material thickness of second layer: Pour Space of material for second layer: Material thickness of third layer: Pour Space of material for third layer: Infiltration On Infiltration rate: Infiltration safety factor: Total Volume Infiltrated (ac-ft): Total Volume Through Riser (ac-ft): Total Volume Through Facility (ac-ft): Percent Infiltrated: Discharge Structure Riser Height: 1.8 ft. Riser Diameter: 0 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(ft) 0 0000 0.0222 0.0444 0.0667 0.0889 0.1111 0. 1333 0.1556 0.1778 0.2000 0.2222 0.2444 0.2667 0.2889 0.3111 0.3333 0.3556 0.3778 0.4000 0.4222 0.4444 0.4667 0.4889 0.5111 0.5333 0.5556 Area(ac) 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 Volume(ac-ft) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0000 0.000 0.000 0.000 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 80.00 ft. 5.00 ft. 0.0001 To 1 0 To 1 0 To 1 2 0.3 0 0 0 0 7.35 1 27.748 0 27.748 100 Discharge(cfs) lnfilt(cfs) 0.000 0.000 0 000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0 000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0 000 0.068 0.000 0.068 0.000 0.068 0 000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0 000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 Aberdeen Ave 02.02.17 2/13/2017 3:50:26 PM Page 7 0.5778 0.009 0.001 0.000 0.068 0.6000 0.009 0.001 0.000 0.068 0.6222 0.009 0.001 0.000 0.068 0.6444 0.009 0.001 0.000 0.068 0.6667 0.009 0.001 0.000 0.068 0.6889 0.009 0.001 0 000 0.068 0.7111 0.009 0.002 0.000 0.068 0.7333 0.009 0.002 0.000 0.068 0.7556 0.009 0.002 0.000 0.068 0.7778 0.009 0.002 0.000 0.068 0.8000 0.009 0.002 0.000 0.068 0.8222 0.009 0.002 0.000 0.068 0.8444 0.009 0.002 0.000 0.068 0.8667 0.009 0.002 0.000 0.068 0.8889 0.009 0.002 0 000 0.068 0.9111 0.009 0.002 0.000 0.068 0.9333 0.009 0.002 0.000 0.068 0.9556 0.009 0.002 0.000 0.068 0.9778 0.009 0.002 0.000 0.068 1.0000 0.009 0.002 0 000 0.068 1.0222 0.009 0.002 0.000 0.068 1.0444 0.009 0.002 0.000 0.068 1.0667 0.009 0.002 0.000 0.068 1.0889 0.009 0.003 0000 0.068 1.1111 0.009 0.003 0.000 0.068 1.1333 0.009 0.003 0.000 0.068 1.1556 0.009 0.003 0.000 0.068 1.1778 0.009 0.003 0000 0.068 1.2000 0.009 0.003 0.000 0.068 1.2222 0.009 0.003 0.000 0.068 1.2444 0.009 0.003 0.000 0.068 1.2667 0.009 0.003 0000 0.068 1.2889 0.009 0.003 0.000 0.068 1.3111 0.009 0.003 0.000 0.068 1.3333 0.009 0.003 0.000 0.068 1.3556 0.009 0.003 0000 0.068 1.3778 0.009 0.003 0.000 0.068 1.4000 0.009 0.003 0.000 0.068 1.4222 0.009 0.003 0.000 0.068 1.4444 0.009 0.004 0.000 0.068 1.4667 0.009 0.004 0.000 0.068 1.4889 0.009 0.004 0.000 0.068 1.5111 0.009 0.004 0.000 0.068 1.5333 0.009 0.004 0.000 0.068 1.5556 0.009 0.004 0.000 0.068 1.5778 0.009 0.004 0.000 0.068 1.6000 0.009 0.004 0.000 0.068 1.6222 0.009 0.004 0.000 0.068 1.6444 0.009 0.004 0.000 0.068 1.6667 0.009 0.004 0 000 0.068 1.6889 0.009 0.004 0.000 0.068 1.7111 0.009 0.004 0.000 0.068 1.7333 0.009 0.004 0.000 0.068 1.7556 0.009 0.004 0.000 0.068 1.7778 0.009 0.004 0.000 0.068 1.8000 0.009 0.005 0.000 0.068 1.8222 0.009 0.005 0.000 0.068 1.8444 0.009 0.005 0.000 0.068 Aberdeen Ave 02.02.17 2/13/2017 3:50:26 PM Page 8 .. 1.8667 0.009 0.005 0.000 0.068 1.8889 0.009 0.005 0.000 0.068 1.9111 0.009 0.005 0.000 0.068 1.9333 0.009 0.005 0.000 0.068 1.9556 0.009 0.005 0.000 0.068 1.9778 0.009 0.005 0.000 0.068 2.0000 0.009 0.005 0.000 0.068 Aberdeen Ave 02.02.17 2/13/2017 3:50:26 PM Page 9 - Analysis Results POC 1 0.00 • , 000 £ ~ 0.00 0 J I . . . IL ooo ~ o.oo,[{-5 l[{-4 11.l:·3 1CE·2 lCE·l '" '" '"' ... - ,,,.,,,.- + + +++:;-++++ + • ·~· .. --. rn ,oo 00+---------------1,., P•rO<lilont Tlm-E><o--~lng + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.37 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.108 Total Impervious Area: 0.262 Flow Frequency Method: Log Pearson Type Ill 178 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000303 5 year 0.000395 10 year 0.000459 25 year 0.000544 50 year 0.00061 100 year 0.000679 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.000678 5 year 0.002079 1 O year 0.003734 25 year 0.006974 50 year 0.01044 100 year 0.015007 < 0.15 cfs increase in the 100-yr storm. ==> Flow control facility not required. Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.001 1950 0.001 0.010 1951 0.001 0.003 1952 0.000 0.000 1953 0.000 0.000 1954 0.000 0.002 1955 0.000 0.001 1956 0.000 0.004 1957 0.000 0.000 1958 0.000 0.000 Aberdeen Ave 02.02.17 2/1312017 3:50:26 PM Page 10 1959 0.000 0.001 1960 0.000 0.003 1961 0000 0.002 1962 0.000 0.000 1963 0.000 0.001 1964 0.000 0.003 1965 0.000 0.001 1966 0.000 0000 1967 0.000 0.008 1968 0.000 0.002 1969 0.000 0.001 1970 0 000 0.000 1971 0.000 0.000 1972 0.002 0.007 1973 0.000 0.000 1974 0000 0.001 1975 0.000 0.001 1976 0.000 0.002 1977 0.000 0.000 1978 0.000 0.000 1979 0000 0 000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.002 1983 0.000 0.001 1984 0.000 0.000 1985 0.000 0.000 1986 0.000 0.001 1987 0000 0.002 1988 0.000 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0015 0.0095 2 0.0006 0.0079 3 0.0006 0.0069 4 0.0003 0.0043 5 0.0003 0.0032 6 0.0003 0.0027 7 0.0003 0.0025 8 0.0003 0.0021 9 0.0003 0.0021 10 0.0003 0.0020 11 0.0003 0.0019 12 0.0003 0.0017 13 0.0003 0.0015 14 0.0003 0.0014 15 0.0003 0.0013 16 0.0003 0.0010 17 0.0003 0.0008 18 0.0003 0.0008 19 0.0003 0.0008 20 0.0003 0.0006 21 0.0003 0.0006 22 0.0003 0.0005 23 0.0003 0.0005 24 0.0003 0.0004 Aberdeen Ave 02.02.17 211312017 3:50:47 PM Page 11 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0002 0.0002 Aberdeen Ave 02.02.17 0.0004 0.0004 0.0004 0.0004 0.0004 0.0003 0.0003 0.0002 0.0002 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 2/13/2017 3:50:47 PM Page 12 Model Default Modifications Total of O changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Aberdeen Ave 02.02.17 2/13/2017 3:51 :02 PM Page 17 Appendix Predeve/oped Schematic .--"A.,I site •. 37ac Aberdeen Ave 02 .02 .17 2/13/201 7 3:51 :02 P M Page 18 - Mitigated Schematic ""~11a. lmpeni •· ~:I Lawn -reas .lil.f·1 1ac pl ~ ~ 1 __:;ravel 1~1 rrrench Bed 1 --. ' Aberd ee n Ave 02 .02. 17 2/13/2017 3 :51 02 PM Page 19 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright© by: Clear Creek Solutions, Inc. 2005-2013; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1 (866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Aberdeen Ave 02.02.17 2/13/2017 3:51:03 PM Page 40 Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section VI, Page 1 TIR Section VI -Special Reports and Studies TIR Section VI Summary: Narrative Please refer to the following reports submitted with the application: 1. Geotechnical Engineering Evaluation by Nelson Geotechnical Associates, Inc., dated October 17, 2016. 2. Supplemental Memorandum to the Geotechnical Engineering Evaluation by Nelson Geotechnical Associates, Inc., dated February 10, 2017. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8soo I t. 425.778.5536 www.cgengineering.com ...,------------- MainOflice 17311 -135 111 Ave :-IE, A-500 Wooclinville, WA 98072 (425) 486-1669 · FAX (425) 481-2510 October 17, 2016 Mr. Curran Kwan Prime Metropolis Properties, Inc. 950 Taraval Street San Francisco, California 94116 NELSON GEOTECHNICAL ASSOCIATES, INC. GEOTECHNICAL ENGINEERS 8c GEOLOGISTS f:nginccring-Gcolog,y Branch 5526 lndw;try Lune, /12 East Wenatchee, WA 98302 (509) 665-7696 · F,\X (509) 665-7692 Geotechnical Engineering Eva! uation Aberdeen Avenue Short Plat and Infiltration 1824 Aberdeen Avenue Renton, Washington NGA Job No. 971516 Dear Mr. Kwan: We are pleased to submit the attached repo1t titled "Geotechnical Engineering Evaluation -Aberdeen Avenue Short Plat and Infiltration -1824 Aberdeen Avenue -Renton, Washington." This report summarizes our observations of the existing surface and subsurface conditions within the site, and provides general recommendations for the proposed site development. Our services were completed in general accordance with the proposal signed by you on September 20, 2016. The site is generally situated on level to gently sloping ground that descends from the east to the west. The site is currently occupied by an existing single-family residence and attached carport within the western portion of the prope11y, a detached garage, and a detached shop building in the south-central and eastern portions of the property, respectively. We understand that the proposed development includes removing the existing site structures and subdividing the property to create new western and eastern parcels. We also understand that a single-family residence and associated pavement and underground utilities will be constructed within each new parcel. Specific grading and stormwater plans were not available at the time this letter was prepared. However, we understand that stormwater is likely to be directed into on-site infiltration systems, if feasible. The City of Renton uses the 2009 King County Surface Water Design Manual to dete1mine the design infiltration rate. On-site infiltration testing is required to determine the suitability of stormwater infiltration. For our use in preparing this report, we have been provided with a preliminary plat map titled "Aberdeen Ave. Subdivision," dated March 24, 2016 and prepared by CG Engineering, Inc., showing the existing and proposed site conditions along with proposed infiltration test locations. We monitored the excavation of four test pits and two infiltration test pits at the site on October 4, 2016. Our explorations indicated that the site is generally underlain by competent native glacial soils, with localized undocumented fill soils encountered up to 4.0 feet in depth. We have concluded that the site is generally compatible with the planned development. We have recommended that any undocumented fill soils be over-excavated and that the new structures be founded on the underlying medium dense or better Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Summary -Page 2 native soils or structural fill extending to these soils for bearing capacity and settlement considerations. These soils should generally be encountered approximately one to four feet below the existing ground surface, based on our explorations. However, deeper areas of loose soil and/or undocumented fill could also exist within unexplored areas of the site. We also performed on-site infiltration testing based on the 2009 King County Smface Water Design Manual. Based on our field testing, the native granular glacial soils encountered at depth within our explorations within the propetty are suitable for on-site stormwater infiltration. In the attached report, we have provided recommendations for infiltration system design and installation. We have also included recommendations for general site grading, foundation and slab support, and drainage. It has been a pleasure to provide service to you on this project. Please contact us if you have any questions regarding this report or require futther information. Sincerely, NELSON GEO TECHNICAL ASSOC/A TES, INC. Khaled M. Shawish, PE Principal TABLE OF CONTENTS INTRODUCTION .......................................................................................................................... I SCOPE ............................................................................................................................................ I SITE CONDITIONS ...................................................................................................................... 2 Surface Conditions.................. . ....... 2 Subsurface Conditions .............................................................................................................. 2 Hydrologic Conditions .............................................................................................................. 3 SENSITIVE AREA EVALUATION ............................................................................................ 3 Seismic Hazard................... . ................... 3 Erosion Hazard ......................................................................................................................... 4 CONCLUSIONS AND RECOMMENDATIONS ....................................................................... 4 General ................................ . . ... 4 Erosion Control ........................................................................................................................ 5 Site Preparation and Grading .................................................................................................... 5 Temporary and Permanent Slopes ............................................................................................ 6 Foundations .............................................................................................................................. 7 Retaining Walls ........................................................................................................................ 8 Structural Fill ............................................................................................................................ 9 Slab-on-Grade ......................................................................................................................... I 0 Pavements ............................................................................................................................... 10 Utilities ................................................................................................................................... 11 Site Drainage .......................................................................................................................... 11 CONSTRUCTION MONITORING .......................................................................................... 13 USE OF THIS REPORT ............................................................................................................. 13 LIST OF FIGURES Figure 1 -Vicinity Map Figure 2 -Site Plan Figure 3 -Soil Classification Chart Figures 4 and 5 -Test Pit Logs NELSON GEOTECHNICAL ASSOCIATES, INC. INTRODUCTION Geotechnical Engineering Evaluation Aberdeen A venue Short Plat and Infiltration 1824 Aberdeen A venue Renton, Washington This report presents the results of our geotechnical engineering investigation and evaluation of the planned Aberdeen Avenue Residential Development project in Renton, Washington. The project site is located at 1824 Aberdeen Avenue in Renton, Washington, as shown on the Vicinity Map in figure 1. The purpose of this study is to explore and characterize the site's smface and subsurface conditions and to provide geotechnical recommendations for the planned site development. For our use in preparing this report, we have been provided with a preliminary plat map titled "Aberdeen Ave. Subdivision," dated March 24, 2016 and prepared by CG Engineering, Inc. The site is relatively level to gently sloping from the east to the west and is currently occupied by a single-family residence structure and attached carpo1t, as well as, two detached shop buildings in the south-central and eastern portions of the site. The proposed development plan consists of demolishing the existing structures and subdividing the current property into two, western and eastern parcels. We understand that stormwater is likely to be directed into on-site infiltration systems, if feasible. The existing site layout and the approximate locations of our explorations are shown on the Site Plan in Figure 2. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Based on our understanding of the planned development and site conditions, the services to be provided by NGA are to: 1. Review available soil and geologic maps of the area. 2. Explore the subsurface soil and groundwater conditions within the site with trackhoe excavated test pits. Trackhoe was subcontracted by NGA. 3. Provide recommendations for emthwork, foundation support, and slabs-on-grade. 4. Provide recommendations for temporary and permanent slopes. 5. Provide recommendations for pavement subgrade. 6. Provide recommendations for site drainage and erosion control. 7. Perform on-site infiltration testing as required. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington 8. Perform grain-size sieve analysis on soil samples, if necessary. NGA File No. 971516 October 17, 2016 Page 2 9. Provide estimates of the infiltration capacity of the soils based on the 2009 King County Surface Water Design Manual. I 0. Provide recommendations for infiltration system installation. 11. Document the results of our findings, conclusions, and recommendations in a written geotechnical report. SITE CONDITIONS Surface Conditions The site consists of a rectangular-shaped parcel covering approximately 0.37-acres. The site is bounded to the north, south, and east by existing residential properties and to the west by Aberdeen Avenue. An existing single-family residential structure and attached carport are located in the western portion of the property. There are two detached garage buildings within the south-central and eastern po11ions of the site. The site topography is relatively level to gently sloping from the east to the west. Vegetation within the site generally consists of grass, underbrush, and scattered trees. We did not observe surface water on the site during our visit on October 5, 2016. Subsurface Conditions Geology: The geologic units for this site are shown on Geologic map of surficial deposits in the Seattle 30' by 60' quadrangle, Washington by Yount, J.C., Minard, J.P., and Dembroff, G.R., (USGS, 1993). The site is mapped as glacial recessional outwash (Qvr). The recessional outwash deposits are described as a poorly to moderately so11ed, stratified mixture of sands and gravels with minor amounts of silt. Our explorations within the prope11y generally encountered fine to medium sand with silt consistent with the description of recessional outwash deposits at depth. Explorations: The subsurface conditions within the site were explored on October 4, 2016 by excavating four test pits and two infiltration test pits to depths ranging from 3.0 to l 0.0 feet below the existing ground surface using a mini-trackhoe. The approximate locations of our explorations are shown on the Schematic Site Plan in Figure 2. A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the test pits. NELSON GEOTECHNICAL ASSOC/A TES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 3 The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 3. The logs of our test pits are attached to this report and are presented as Figures 4 and 5. We present a brief summary of the subsurface conditions in the following paragraphs. For a detailed description of the subsurface conditions, the logs of the test pits should be reviewed. Within Test Pit 2 through 3 and Infiltration Pit 1 through 2 we encountered 0.5 to 1.5 of grass and surficial topsoil. Underlying the topsoil we generally encountered medium dense or better, light brown to gray brown, fine to medium sand with gravel, and minor amounts of silt, which we interpreted as native recessional outwash deposits. These explorations terminated within the native recessional outwash deposits at depths in the range of 8.0 to 9.5 feet below the existing ground surface. Within Test Pit 1 and Test Pit 4 we encountered 0.6 to 1.5 feet of grass and surficial topsoil underlain by 2.2 to 3.4 feet of loose to medium dense, fine to medium sand with silt, intermixed with concrete rubble that we interpreted as undocumented fill soils. Underlying the fill in Test Pit 1, we encountered medium dense to dense, light-brown to gray-brown, fine to medium sand with silt and trace gravel that we interpreted as native recessional outwash deposits. Test Pit 4 was terminated at a concrete drain pipe within undocumented fill soils at 3.0 feet below the existing ground surface, while Test Pit 1 was terminated in native recessional outwash soils at approximately 10.0 feet below the existing ground surface. Hydrologic Conditions Groundwater seepage was not encountered in our explorations. If groundwater seepage occurs on this site, we would interpret the water to be perched water. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of a relatively low permeability material. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of perched groundwater to decrease during drier times of the year and increase during wetter periods. SENSITIVE AREA EVALUATION Seismic Hazard We reviewed the 2015 International Building Code (!BC) for seismic site classification for this project. Since medium dense or better glacial soils were generally encountered underlying the site at depth, the site conditions best fit the !BC description for Site Class D. NELSON GEOTECHNICAL ASSOC/A TES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 4 Hazards associated with seismic activity include liquefaction potential and amplification of ground motion. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. It is our opinion that the competent native glacial soils interpreted to underlie the site have a low potential for liquefaction or amplification of ground motion. Erosion Hazard The criteria used for determination of the erosion hazard for affected areas include soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey of King County Area. Washington, by the Soil Conservation Service (SCS) lists the soils within the project area as Indianola Loamy Sand, 5 to 15 percent slopes. The erosion hazard for these soils is listed as slight. It is our opinion that the site would have a slight erosion hazard for areas where the soils are exposed. It is also our opinion that the erosion hazard for site soils should be low in areas where vegetation is not disturbed. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion from a geotechnical standpoint that the site is generally compatible with the planned development. Our explorations indicated that the site is generally underlain by competent native glacial soils at depth. However, our explorations within the central and eastern portion of the property encountered approximately 3.0 to 4.0 feet of unsuitable undocumented fill soils. The native glacial soils encountered at depth should provide adequate support for foundation, slab, and pavement loads. We recommend that the planned structures be designed utilizing shallow foundations. Footings should extend through any loose soil or undocumented fill soils and be founded on the underlying medium dense or better native soil, or structural fill extending to these soils. The native medium dense or better soils should typically be encountered approximately one to four feet below the existing surface, based on our explorations. We should note that localized areas of deeper unsuitable soils and/or undocumented fill could be encountered at this site. This condition would require additional excavations in foundation, slab, and pavement areas to remove the unsuitable soils. It is our opinion that the native granular glacial soils encountered within the prope11y are suitable for on- site infiltration systems. The subsurface soils encountered at depth are generally fine to medium sands with varying amounts of silt. We also did not observe groundwater in our explorations to the depths explored. We recommend on-site infiltration systems be founded in native recessional outwash deposits. NELSON GEOTECHN/CAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 5 The storm water management system should be designed in accordance with 2009 King County Surface Water Design Manual. This is frn1her discussed in the Stormwatcr Infiltration subsection of this report. The surficial soils encountered on this site are considered moisture-sensitive and may disturb easily when wet. We recommend that construction take place during the drier summer months, if possible. If construction is to take place during wet weather, the soils may disturb and additional expenses and delays may be expected due to the wet conditions. Additional expenses could include the need for placing a blanket of rock spalls to protect exposed subgrades and construction traffic areas. Some of the native on- site soils may be suitable for use as structural fill depending on the moisture content of the soil during construction. This will depend on the moisture content of the soils at the time of construction. NGA should be retained to determine if the on-site soils can be used as structural fill material during construction. Erosion Control The erosion hazard for the on-site soils is interpreted to be slight for exposed soils, but actual erosion potential will be dependent on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during construction should be protected from erosion. Erosion control measures may include dive1ting surface water away from the stripped or disturbed areas. Silt fences and/or straw bales should be erected to prevent muddy water from leaving the site. Disturbed areas should be planted as soon as practical and the vegetation should be maintained until it is established. The erosion potential of areas not stripped of vegetation should be low. Site Preparation and Grading After erosion control measures are implemented, site preparation should consist of stripping the topsoil, loose soils and/or undocumented fill from foundation, slab, pavement areas, and other structural areas, to expose medium dense or better native soils. The stripped soil should be removed from the site or stockpiled for later use as a landscaping fill. Based on our observations, we anticipate stripping depths of approximately one to four feet across the site. It should be noted that additional stripping may be required if areas of undocumented fill and/or loose soil are encountered in unexplored areas of the site. Specific plans for protecting existing structures, driveway, and utilities should be devised during the planning phase of the project and should be made clear to contractors during the bidding phase. NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 6 After site stripping, if the exposed subgrade is loose, it should be compacted to a non-yielding condition and then proof-rolled with a heavy rubber-tired piece of equipment. Areas observed to pump or weave during the proof-roll test should be reworked to structural fill specifications or over-excavated and replaced with properly compacted structural fill or rock spalls. If loose soils are encountered in the pavement areas, the loose soils should be removed and replaced with rock spalls or granular structural fill. If significant surface water flow is encountered during construction, this flow should be diverted around areas to be developed, and the exposed subgrades should be maintained in a semi-dry condition. If wet conditions are encountered, alternative site stripping and grading techniques might be necessary. These could include using large excavators equipped with wide tracks and a smooth bucket to complete site grading and covering exposed subgrade with a layer of crushed rock for protection. If wet conditions are encountered or construction is attempted in wet weather, the subgrade should not be compacted as this could cause further subgrade disturbance. In wet conditions it may be necessary to cover the exposed subgrade with a layer of crushed rock as soon as it is exposed to protect the moisture sensitive soils from disturbance by machine or foot traffic during construction. The prepared subgrade should be protected from construction traffic and surface water should be divetted around areas of prepared subgrade. The site soils are considered to be moisture-sensitive and may disturb when wet. We recommend that construction take place during the drier summer months if possible. However, if construction takes place during the wet season, additional expenses and delays should be expected due to the wet conditions. Additional expenses could include the need for placing a blanket of rock spalls on exposed subgrades, construction traffic areas, and paved areas prior to placing structural fill. Wet weather grading will also require additional erosion control and site drainage measures. Some of the on-site soils may be suitable for use as structural fill, depending on the moisture content of the soil at the time of construction. NGA should be retained to evaluate the suitability of all on-site and imported structural fill material during construction. Temporary and Permanent Slopes Temporary cut slope stability is a function of many factors, including the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations at all times as indicated in OSHA guidelines for cut slopes. NELSON GEOTECHNICAL ASSOC/A TES, INC. Gcotcchnlcal Engineering Evaluation Aberdeen Avenue Shoti Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 7 The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. For planning purposes, we recommend that temporary cuts in the upper undocumented fill soils be no steeper than 2 Horizontal to 1 Vertical (2H: IV). Temporary cuts in the competent native glacial soils at depth should be no steeper than l.5H:1V. If significant groundwater seepage or surface water flow were encountered, we would expect that flatter inclinations would be necessary. We recommend that cut slopes be protected from erosion. The slope protection measures may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not recommend vertical slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to appropriate OSHA/WISHA regulations. Temporary shoring may be needed where these recommended inclinations cannot be met due to existing structures or property boundaries. Permanent cut and fill slopes should be no steeper than 2H: l V. However, flatter inclinations may be required in areas where loose soils are encountered. Permanent slopes should be vegetated and the vegetative cover maintained until established. Foundations Conventional shallow spread foundations should be placed on medium dense or better native soils, or be supported on structural fill or rock spalls extending to those soils. Medium dense soils should be encountered approximately one to four feet below ground surface based on our explorations. Where undocumented fill or less dense soils are encountered at footing bearing elevation, the subgrade should be over-excavated to expose suitable bearing soil. The over-excavation may be filled with structural fill, or the footing may be extended down to the competent native soils. If footings are supported on structural fill, the fill zone should extend outside the edges of the footing a distance equal to one half of the depth of the over-excavation below the bottom of the footing. Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection and bearing capacity considerations. Foundations should be designed in accordance with the 20 I 5 !BC. Footing widths should be based on the anticipated loads and allowable soil bearing pressure. Water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation p1ior to placing concrete. NELSON GEOTECHNICAL ASSOC/A TES, INC. . , Geotechnical Engineering Evaluation Aberdeen A venue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 8 For foundations constructed as outlined above, we recommend an allowable design bearing pressure of not more than 2,000 pounds per square foot (psf) be used for the design of footings founded on the medium dense or better native soils or structural fill extending to the competent native material. The foundation bearing soil should be evaluated by a representative of NGA. We should be consulted if higher bearing pressures are needed. Current !BC guidelines should be used when considering increased allowable bearing pressure for short-term transitoty wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than !-inch total and Yi-inch differential between adjacent footings or across a distance of about 20 feet, based on our experience with similar projects. Lateral loads may be resisted by friction on the base of the footing and passive resistance against the subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent fluid density of 200 pounds per cubic foot (pct) should be used for passive resistance design for a level ground surface adjacent to the footing. This level surface should extend a distance equal to at least three times the footing depth. These recommended values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and passive resistance, respectively. To achieve this value of passive resistance, the foundations should be poured "neat" against the native medium dense soils or compacted fill should be used as backfill against the front of the footing. We recommend that the upper one foot of soil be neglected when calculating the passive resistance. Retaining Walls Specific grading plans for this project were not available at the time this report was prepared, but retaining walls may be incorporated into project plans. In general, the lateral pressure acting on subsurface retaining walls is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall drainage conditions, and the inclination of the backfill. For walls that are free to yield at the top at least one thousandth of the height of the wall (active condition), soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing (at-rest condition). We recommend that walls supporting horizontal backfill and not subjected to hydrostatic forces, be designed using a triangular earth pressure distribution equivalent to that exerted by a fluid with a density of 35 pcf for yielding (active condition) walls, and 55 pcf for non- yielding (at-rest condition) walls. NELSON GEOTECHNICAL ASSOCIATES, INC . Geotecbnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 9 ----------------- These recommended lateral earth pressures are for a drained granular backfill and are based on the assumption of a horizontal ground surface behind the wall for a distance of at least the subsurface height of the wall, and do not account for surcharge loads. Additional lateral ea1ih pressures should be considered for surcharge loads acting adjacent to subsurface walls and within a distance equal to the subsurface height of the wall. This would include the effects of surcharges such as traffic loads, floor slab loads, slopes, or other surface loads. We could consult with the structural engineer regarding additional loads on retaining walls during final design, if needed. The lateral pressures on walls may be resisted by friction between the foundation and subgrade soil, and by passive resistance acting on the below-grade portion of the foundation. Recommendations for frictional and passive resistance to lateral loads are presented in the Foundations subsection of this report. All wall backfill should be well compacted as outlined in the Structural Fill subsection of this report. Care should be taken to prevent the buildup of excess lateral soil pressures due to over-compaction of the wall backfill. This can be accomplished by placing wall backfill in 8-inch loose lifts and compacting the backfill with small, hand-operated compactors within a distance behind the wall equal to at least one-half the height of the wall. The thickness of the loose lifts should be reduced to accommodate the lower compactive energy of the hand-operated equipment. The recommended level of compaction should still be maintained. Permanent drainage systems should be installed for retaining walls. Recommendations for these systems are found in the Subsurface Drainage subsection of this report. We recommend that we be retained to evaluate the proposed wall drain backfill material and observe installation of the drainage systems. Structural Fill General: Fill placed beneath foundations, pavement, or other settlement-sensitive structures should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. Field monitoring procedures would include the performance of a representative number of in-place density tests to document the attainment of the desired degree of relative compaction. The area to receive the fill should be suitably prepared as described in the Site Preparation and Grading subsection prior to beginning fill placement. NELSON GEOTECHNICAL ASSOC/A TES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Sho1t Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 10 -----------------------·-----~------------------- Materials: Structural fill should consist of a good quality, granular soil, free of organics and other deleterious material, and be well graded to a maximum size of about three inches. All-weather fill should contain no more than five-percent fines (soil finer than U.S. No. 200 sieve, based on that fraction passing the U.S. 3/4-inch sieve). Some of the more granular on-site soils may be suitable for use as structural fill depending on the moisture content of the soil during construction. We should be retained to evaluate all proposed structural fill material prior to placement. Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas and pavement subgrade should be compacted to a minimum of 95 percent of its maximum dry density. Maximum dry density, in this repo1i, refers to that density as determined by the ASTM D-1557 Compaction Test procedure. The moisture content of the soils to be compacted should be within about two percent of optimum so that a readily compactable condition exists. It may be necessary to over- excavate and remove wet soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Slab-on-Grade Slabs-on-grade should be supported on subgrade soils prepared as described in the Site Preparation and Grading subsection of this report. We recommend that all floor slabs be underlain by at least six inches of free-draining gravel with less than three percent by weight of the material passing Sieve #200 for use as a capillary break. We recommend that the capillary break be hydraulically connected to the footing drain system to allow free drainage from under the slab. A suitable vapor barrier, such as heavy plastic sheeting (6-mil minimum), should be placed over the capillary break material. An additional 2-inch-thick moist sand layer may be used to cover the vapor baiTier. This sand layer may be used to protect the vapor barrier membrane and to aid in curing the concrete. Pavements Pavement subgrade preparation and structural filling where required, should be completed as recommended in the Site Preparation and Grading and Structural Fill subsections of this report. The pavement subgrade should be proof-rolled with a heavy, rubber-tired piece of equipment, to identify soft or yielding areas that require repair. The pavement section should be underlain by a minimum of six NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 11 ---------------·------------------------------------------------------~------------ inches of clean granular pit run or crushed rock. We should be retained to observe the proof-rolling and recommend repairs prior to placement of the asphalt or hard surfaces. Utilities We recommend that underground utilities be bedded with a minimum 12 inches of pea gravel prior to backfilling the trench with on-site or imported material. Trenches within settlement sensitive areas should be compacted to 95% of the modified proctor as described in the Structural Fill subsection of this report. Trenches located in non-structural areas should be compacted to a minimum 90% of the maximum dry density. Site Drainage Infiltration: It is our opinion that the subsurface soils within the site are suitable for typical stormwater infiltration. We recommend that any infiltration systems within this property be designed utilizing the recommended long-term design infiltration rate provided below. We conducted two on-site infiltration tests within the central and eastern portion of the property based on the 2009 King County Surface Water Design Manual to determine a long-term design infiltration rate for the on-site infiltration systems. The test locations are shown as Inf-] and Inf-2 on the Site Plan in Figure 2. Infiltration Pits l and 2 were performed at respective depths of approximately 2.0 feet below the existing ground surface. We installed a six-inch diameter ve11ical tube into the native soil at the test locations within Infiltration Pit l and 2. Approximately two inches of pea gravel was placed over the native soil. We made repeated measurements of the time for the infiltration of six inches of water into the native sand soil. The average infiltration rate from each data set was used for the measured infiltration rate. The measured infiltration rates obtained in the field were 116.03 inches per hour for Infiltration Pit 1 and 6 I .31 inches per hour for Infiltration Pit 2. We have not applied a factor of safety to the in-place infiltration test results. We referenced Equation 5-11 within Chapter 5.4. l of the 2009 King County Surface Water Design Manual that applies adequate correction factors to the field measured infiltration rate to generate a long- term design infiltration rate. Correction factors of 0.30, 0.50, and 0.80 were utilized in this equation for Ftesting, Fgeometry, Fplugging, respectively. Using these conection factors along with the lower of the two field measured infiltration rates, we calculated a long-term design infiltration rate of 7.35 inches per hour. We recommend that the on-site infiltration systems exposing the competent granular glacial outwash soils be designed utilizing the 7.35 inch per hour rate. We should be retained during NELSON GEOTECHNICAL ASSOC/A TES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 12 construction to evaluate the soils exposed in the infiltration systems to verify that the soils are appropriate for infiltration. We recommend that the infiltration trenches extend through any organic soil or fill to expose undisturbed native granular outwash soils. We should be retained to verify the existence of such material at the time of construction. The storm water management systems should be designed in accordance with the King County Stormwater Design Manual. We recommend that any proposed infiltration systems be located as to not negatively impact any proposed or existing nearby structures and also meet all required setbacks from existing property lines, structures, and sensitive areas in accordance with the City of Renton code. The stormwater manual recommends a three-foot separation between the base of an infiltration system and any underlying bedrock, impermeable horizon, or groundwater. We did not encounter any groundwater in our explorations to the depths explored. Surface Drainage: The finished ground surface should be graded such that stormwater is directed to an appropriate stormwater collection system. Water should not be allowed to stand in any areas where footings, slabs, or pavements are to be constructed. Final site grades should allow for drainage away from the residences. We suggest that the finished ground be sloped at a minimum gradient of three percent, for a distance of at least 10 feet away from the residences. Surface water should be collected by permanent catch basins and drain lines, and be discharged into an appropriate discharge system. The overflow water should be dispersed to discharge into an appropriate location. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where the water can be pumped out and routed into a permanent storm drain. We recommend the use of footing drains around the structures. Footing drains should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimum 4-inch- diameter, rigid, slotted or perforated, PVC pipe surrounded by free-draining material wrapped in a filter fabric. We recommend that the free-draining material consist of an 18-inch-wide zone of clean (less than three-percent fines), granular material placed along the back of walls. Pea gravel is an acceptable drain material. The free-draining material should extend up the wall to one foot below the finished surface. The top foot of backfill should consist of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines migration into the footing drain. Footing drains should discharge into NELSON GEOTECHNICAL ASSOC/A TES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and Infiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 13 tightlines leading to an appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to wall or footing drains. CONSTRUCTION MONITORING We should be retained to provide construction monitoring services during the earthwork phase of the project to evaluate subgrade conditions, temporary cut conditions, fill compaction, and drainage system installation. USE OF THIS REPORT NGA has prepared this report for Cu1rnn Kwan with Prime Metropolis Properties, Inc. and his agents, for use in the planning and design of the development on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre-construction meetings if requested. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this report was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. 0-0-0 NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation Aberdeen Avenue Short Plat and lnfiltration Renton, Washington NGA File No. 971516 October 17, 2016 Page 14 It has been a pleasure to provide service to you on this project. If you have any questions or require fut1her information, please call. Sincerely, NELSON GEOTECHNICAL ASSOC/A TES, INC, Alex B. Rinaldi, GIT Staff Geologist LEE S. BELLAH Lee S. Bellah, LG Project Geologist Khaled M. Sha wish Principal LSB:KMS:dy Five Figures Attached NELSON GEOTECHNICAL ASSOC/A TES, INC. ' ~ VICINITY MAP N Not to Scale (I z ,':, '" z ,,1 ,', /•1111 51 l·lf 2.',1:1"1Sl I NF/;;11) Pi' ® ···H'. ::=::irrJ Sr {: Isl: ·,·.:.,<J :,. 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(D (D rr (D _::, (/) ::, ~ ;:::.: ~ < (D ::::::--(D "TI [l) ::, -~c [l) 0 (D ::, ::, (/) ~!" ias .. ~ ~-'~ ~:: f;ji '" !H H 'a' ;,Q H-3 ~~:! -~· ~ig ~~~ •• , . " " 0 " m n " z ii > r "' z 0 z m m • • " " m 0 r 0 0 • " • ::,- 0 ;:i. J1 !!l. I z "' :,,r "' en "'0 oz !2 Gl )> "' ---1 0 "'---1 Ul "' • 0 -J: z z !" -0 )> r -z ~ -" I Cl ~ ;- - ilf -iii" o· , a I "' ~ "' INF-1 I -•-I TP-1 I -•-I l w z f a, ~ Q C a, a, m <( lTP-4 I T - LEGEND Property line Number and approximate location of test pit Number and approximate location of test pit I r Site Plan Proposed residence I /-W""'-•11;•-· r-.,;,,r,,_n, Proposed residence __..:..---,::i..,. INF-1 •- I TP-1 '.~,-,-,---'---+-+"·,,___ __ +-......;s=.._J I __L--~ .. ..:.~·-· -~- "" I I -•- Lot 1 I I I \ INF-2 = TP-3 I ---Lot 2 I { tj) j F =ir-Ll w...::1 .. -, 1 ' Existing residence to be removed '--11;J>>f,c'11 .. N'N<I Existing garage to be removed Existing residence to be removed 0 40 80 Scale: 1 inch = 40 feet • I C) ~ "I Reference: Site plan based on a plan dated March 24 2016 titled "Averdeen Ave. SL,Jbdivision." prepared by CG En N:\2016 NGA Project Folders\9715-16 Aberdeen Avenue, Renton lnfiltrat!on\Drafling\SP .dwg N UNIFIED SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS SYMBOL GROUP NAME CLEAN GW WELL-GRADED, FINE TO COARSE GRAVEL COARSE-GRAVEL GRAVEL GP POORLY-GRADED GRAVEL GRAINED MORE THAN 50 % GRAVEL OF COARSE FRACTION GM SIL TY GRAVEL RETAINED ON SOILS NO. 4 SIEVE WITH FINES GC CLAYEY GRAVEL SAND CLEAN SW WELL-GRADED SAND, FINE TO COARSE SAND SAND SP POORLY GRADED SAND MORE THAN 50 % RETAINED ON MORE THAN 50 % NO. 200 SIEVE OF COARSE FRACTION SAND SM SILTY SAND PASSES NO. 4 SIEVE WITH FINES SC CLAYEY SAND FINE-SILT AND CLAY ML SILT INORGANIC GRAINED LIQUID LIMIT CL CLAY LESS THAN 50 % SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY MH SILT OF HIGH PLASTICITY, ELASTIC SILT MORE THAN 50 % INORGANIC PASSES LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FLAT CLAY NO. 200 SIEVE 50 % OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT f u ~ HIGHLY ORGANIC SOILS PT PEAT ~ ~ NOTES: ~ 1) Field classification is based on visual SOIL MOISTURE MODIFIERS: i s examination of soil in general C ~ accordance with ASTM D 2488-93. Dry-Absence of moisture, dusty, dry to ~ the touch " 2) Soil classification using laboratory tests ' Moist -Damp, but no visible water. ! is based on ASTM D 2488-93. • • Wet -Visible free water or saturated, ~ 3) Descriptions of soil density or • usually soil is obtained from ~ consistency are based on ~ interpretation of blowcount data, below water table ~ ;:: visual appearance of soils, and/or I test data. ~ 0 Project Number " ~ELSON GEOTECHNICAL No. Date Revision By CK 6 Aberdeen Avenue Short Plat • 971516 NGA ASSOCIATES, INC. e Infiltration 1 1015116 Orlglnal DPN ABR ~ GEOTECHNICAL ENGINEERS Be GEOLOGISTS ~ z Figure 3 Soil Classification Chart 17J11-1J.5,j,J,l'<'J ~"'·"-'500 Snghaml,~ Coont'j (~l~)JJ?-161;9 w Woo<fuwii... WJ, 1grm W•n•ld'!oe/Ch<llon 1509) 6!1~71196 s (':!5)l6'l-161i91F••~at-151a www.11ej>0"'"0<11oc11.com ~ z DEPTH (FEET] TEST PIT ONE 0.0 -0.2 0.2 -0.6 0.6 -4.0 4.0 -10.0 TEST PIT TWO 0.0 -0.2 0.2 -0.5 0.5 -6.0 6.0 -9.0 TEST PIT THREE 0.0 -0.2 0.2 -0.9 0.9 -8.0 8.0 -9.5 ABR:LSB USC LOG OF EXPLORATION SOIL DESCRIPTION GRASS AND ROOTS DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL) LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, CONCRETE RUBBLE, TRACE ROOTS, AND GRAVEL (LOOSE TO MEDIUM DENSE, MOIST] (FILL) LIGHT BROWN TO GRAY BROWN, FINE TO MEDIUM SAND WITH SILT AND TRACE GRAVEL SP-SM (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE COLLECTED AT 3.0, 6.0, 9.0, 10.0 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED SLIGHT TEST PIT CAVING WAS ENCOUNTERED TEST PIT WAS COMPLETED AT 10.0 FEET ON 1014116 GRASS AND ROOTS DARK BROWN, SIL TY FINE TO MEDIUM SAND WITH GRAVEL AND ROOTS/ORGANICS (LOOSE TO MEDIUM DENSE, MOIST] (TOPSOIL) SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, TRACE GRAVEL AND ROOTS (MEDIUM DENSE TO DENSE, MOIST) SP-SM BROWN-GRAY, FINE TO COARSE SAND WITH SILT, GRAVEL, AND TRACE ROOTS (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE COLLECTED AT 2.0, 6.0, AND 9.0 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED SLIGHT TO MODERATE TEST PIT CAVING WAS ENCOUNTERED FROM 6.0 TO 9.0 FEET TEST PIT WAS COMPLETED AT 9.0 FEET ON 1014116 GRASS AND ROOTS DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, IRON-OXIDE STAINING, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST] (TOPSOIL) SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, TRACE IRON-OXIDE WEATHERING, ROOTS AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST] SP-SM GRAY-BROWN, FINE TO COARSE SAND WITH SILT, TRACE IRON-OXIDE WEATHERING, ROOTS AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST] SAMPLES WERE COLLECTED AT 2.5, 6.5, AND 9.0 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED SLIGHT TEST PIT CAVING WAS ENCOUNTERED FROM 0.2 TO 9.5 FEET TEST PIT COMPLETED AT 9.5 FEET ON 1014116 NELSON GEOTECHNICAL ASSOCIATES, INC. FILE NO 971516 FIGURE4 DEPTH (FEET) TEST PIT FOUR a.a -0.2 0.2 -0.8 0.8 -2.5 2.5 -3.0 INFILTRATION PIT ONE USC LOG OF EXPLORATION SOIL DESCRIPTION GRASS AND ROOTS DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, IRON-OXIDE STAINING, AND ROOTS (LOOSE TO MEDIUM DENSE, MOISD (TOPSOIL) LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, TRACE ROOTS AND GRAVEL (LOOSE TO MEDIUM DENSE, MOISD (FILL) DRAIN ROCK AND CONRETE DRAIN PIPE NO SAMPLES WERE COLLECTED GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED INFILTRATION PIT CAVING WAS NOT ENCOUNTERED INFIILTRATION PIT COMPLETED AT 3.0 FEET ON 1014116 0.0 -0.2 GRASS AND ROOTS 0.2-1.0 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, IRON-OXIDE STAINING, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL) 1.0-8.0 INFILTRATION PIT lWO SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, IRON-OXIDE WEATHERING AND TRACE GRAVEL (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE COLLECTED AT 3.5 AND 8.0 GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED SLIGHT INFILTRATION PIT CAVING WAS ENCOUNTERED FROM 1.0 TO 8.0 FEET INFIILTRATION PIT COMPLETED AT 8.0 FEET ON 1014116 0.0 -0.2 GRASS AND ROOTS 0.2 -1.5 DARK BROWN, SIL TY FINE TO MEDIUM SAND WITH GRAVEL, IRON-OXIDE STAINING, AND ROOTS (LOOSE TO MEDIUM DENSE, MOISD (TOPSOIL) 1.5-7.0 7.0 -9.0 ABR:LSB SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, GRAVEL, IRON-OXIDE WEATHERING, AND TRACE ROOTS (MEDIUM DENSE TO DENSE, MOIST) SP-SM GRAY-BROWN, FINE TO COARSE SAND WITH SILT AND TRACE GRAVEL (MEDIUM DENSE TO DENSE, MOISD SAMPLES WERE COLLECTED AT 5.0, 7.0, AND 9.0 GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED SLIGHT INFILTRATION PIT CAVING WAS ENCOUNTERED FROM 1,5 TO 9.0 FEET INFIil TRATION PIT COMPLETED AT 9.0 FEET ON 1014/16 NELSON GEO TECHNICAL ASSOC/A TES, INC. FILE NO 971516 FIGURE 5 DATE: TO: CC: FROM: RE: NELSON GE:OTECHNICAL ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS Main Office 173!1-!35 1hi\veNE,A-500 Woodinville, WA 98072 (425) 486-1669 · FAX (425) 481-2510 Engineering-Geology Branch 5526 Industry Lane, #2 East Wenatchee, WA 98802 (509) 665-1696 · FAX (509) 665-7692 MEMORANDUM February I 0, 2017 Mr. Curran Kwan Mr. Greg Guillen -CG Engineering Khaled M. Shawish, PE Lee S. Bellah, LG Aberdeen A venue Short Plat Supplemental Memorandum 1824 Aberdeen Avenue Renton, Washington NGA File No. 971516 INTRODUCTION This memo presents our responses to review comments raised by the City of Renton regarding the proposed residence project located at 1824 Aberdeen Avenue in Renton, Washington. We have previously prepared a geotechnical engineering evaluation for the project site titled "Aberdeen Avenue Short Plat and Infiltration," dated October 17, 2016. We understand that concerns have been raised by the City of Renton Depaiiment of Community and Economic Development regarding geotechnical aspects of the on-site infiltration testing. Their comments were presented in a comment letter titled "Utility and Transportation Comments for Aberdeen Avenue Short Plat," dated January 31, 2017, prepared by Mr. Ian Fitz-James. For our use in preparing this memo, we were provided with Plan Sheets Cl.I through C3.l titled "Aberdeen Avenue Subdivision," dated December 16, 2016, prepared by CG Engineering. In the following sections, we summarize the geotechnical concern raised by the City of Renton, followed by our responses to each concern. Aberdeen Avenue Short Plat Supplemental Memorandum I 8 24 Aberdeen A venue Renton, Washington CITY OF RENTON REVIEW CONCERNS AND OUR RESPONSES Review Comment Surface Water 3.a.: NGA File No. 971516 Febrnary 10, 2017 Page 2 Section 5.2.1 of the RSWDM requires that infiltration tests be pe,formed al the elevation of botlom of the proposed infiltration facility (Elev. 293 as shown on plans). Provide verification of the depth of the infiltration tests. The geotechnical report states that the infiltration tests were pe,formed al approximately two feel below existing grade which is several feet above botlom of proposed facility Response: Based on our review of the prnvided plans, we understand that storm water generated within the site will be directed to a 5-foot wide by 80-foot long by 2.0 foot thick gravel-filled infiltration trench located within the driveway area along the southern po1iion of the site. The base of the infiltration trench is prnposed to be at an apprnximate elevation of 293 feet. At the time our infiltration testing was performed within the site, the exact location, and overall size and depth of the proposed infiltration system was unknown. As a part of our previous evaluation of the prope,ty, we performed several additional deeper test pit explorations throughout the prope1iy that extended up to 10.0 feet below the existing grnund surface. All of our test pits performed within the site encountered and were terminated within native glacial recessional outwash soils consisting of fine to medium sand with gravel and silt. Test Pit l and Infiltration Pit I located immediately north of the proposed infiltration area were located at a grnund surface elevation of 298 feet. Test Pit I extended down to 10.0 feet below the existing ground surface (approximate elevation of 288 feet) and encountered native glacial recessional outwash soils to the depth explored. Our on-site infiltration test performed within Infiltration Pit I was conducted in the native recessional outwash soils at a depth of 2.0 feet below the existing ground surface (apprnximate elevation of 296 feet). After the infiltration testing was concluded in lnfiltration Pit I, this pit was further excavated an additional six feet (approximate elevation of 290 feet) and encountered the same granular native recessional outwash soils to the depth explored. Based on this, it is our opinion that the proposed infiltration trench located at an elevation of 293 feet should encounter native glacial recessional outwash soils similar to the soils that we conducted our on-site infiltration testing into, and these soils appear to extend at least five feet below the prnposed infiltration facility. It is also om opinion, that the recommended long-term design infiltration rate of 7.35 inches per hour should be valid at the planned infiltration trench depth. We recommend that we be retained during construction to verify the soils exposed in the entire infiltration area are similar to the soils encountered during our explorations. NELSON GEO TECHNICAL ASSOC/A TES, INC. Aberdeen Avenue Short Plat Supplemental Memorandum 1824 Aberdeen Avenue Renton, Washington CLOSURE NGA File No. 971516 February 10, 2017 Page 3 We trust this memorandum should satisfy your needs at this time. Please contact us if you have any questions or require additional services. 0-0-0 NELSON GEO TECHNICAL ASSOC/A TES, INC. Aberdeen Ave Subdivision 16037.20 Technical Information Report TIR Section VII Narrative TIR Section VII -Other Permits February 16, 2017 Section VII, Page 1 Other permits are not anticipated that would contain more restrictive drainage plan requirements. C5 ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www .cge ngi nee ring.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section VIII, Page 1 TIR Section VIII -CSWPPP Analysis and Design TIR Section VIII Summary Narrative This section of the TIR is to provide a summary of erosion controls and source controls for the site. The project proposes to subdivide a single 16,161 sf parcel in the R-8 zone into 2 individual single-family lots. The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The project will add more than 2,000 sf of impervious surfaces and so must meet the Full Drainage requirements from the 2016 King County Surface Water Design Manual as amended by the City of Renton. The project will construct the necessary stormwater improvements for the access/utility tract and lots, but development of Lots 1 and 2 will occur at a later date. ESC and SWPPS measures were chosen per Section D.2 the 2016 King County Surface Water Design Manual. Less than 1 acre of land will be disturbed and therefore the Department of Ecology SWPPP and Construction Stormwater General Permit is not required. ESC Measures The following ESC measures are suggested for each category below; 1. Clearing Limits: To protect adjacent properties, existing trees, and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. The BMPs relevant to marking the clearing limits that will be applied for this project include: • High Visibility Plastic or Metal Fence 2. Cover Measures Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. Temporary cover shall be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). The suggested BMPs for soil stabilization that shall be used on this project include: • Temporary & Permanent Seeding • Mulching • Nets & Bia n kets • Plastic Covering 3. Perimeter Protection All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged. Silt fences will be installed on ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section VIII, Page 2 the downstream sides of the site. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence 4. Traffic Area Stabilization A stabilized construction entrance will be established to the west side of the site using the existing gravel driveway. • Stabilized Construction Entrance 5. Sediment Retention The site is small enough that perimeter protection is expected to be adequate for sediment retention onsite. 6. Surface Water Collection The site is small enough that perimeter protection is expected to be adequate for sediment retention onsite. 7. Dewatering Control Dewatering is not anticipated. 8. Dust Control Dust control will be used to minimize wind transport of soil. Water and/or other dust control measures may be used upon approval by the County. • Dust Control 9. Flow Control Increases in the 2-year and 10-year runoff event is expected to be small due to the size of the site. Flow control measures are not proposed. 10. Protect Existing and Proposed Flow Control BMPs Stormwater facilities and on-site BMPs areas are identified on the Temporary Erosion Control Plan. These areas shall be protected from sedimentation and soil compaction that would adversely affect infiltration. 11. Maintain BMPs BMPs will be maintained and repaired as necessary throughout construction. The CSWPP supervisor shall review the site for ESC and SWPPS at least weekly and within 24 hours of significant storms. All temporary erosion and sediment control BMPs will be removed within 30 days after achieving final site stabilization. 12. Manage the Project Projects shall assign a qualified CSWPPP supervisor to be the primary contact for ESC and SWPPP issues and reporting. CT? ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report SWPPS Measures The following SWPPS measures are expected for the site. 1. Concrete Handling February 16, 2017 Section VIII, Page 3 Management practices per Section D.2.2.1 "Concrete Handling" shall be utilized any time concrete is used to minimize and eliminate concrete, concrete process water, and concrete slurry runoff. 2. Concrete Washout Area Prevent or reduce the discharge of pollutants to stormwater from concrete waste by conducting washout off-site, or performing on-site washout in a designated area to prevent pollutants from entering surface waters or ground water. 3. Sawcutting and Surfacing Pollution Prevention Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include, but are not limited to, sawing, coring, grinding, roughening, hydrodemolition, bridge and road surfacing. 4. Material Delivery, Storage and Containment These procedures are suitable for use at all construction sites with delivery and storage of the following materials: Petroleum products such as fuel, oil and grease; Soil stabilizers and binders (e.g. Polyacrylamide); Fertilizers, pesticides and herbicides; Detergents; Asphalt and concrete compounds; Hazardous chemicals such as acids, lime, adhesives, paints, solvents and curing compounds; Any other material that may be detrimental if released to the environment. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www .cge ngi nee ring.com Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section IX, Page 1 TIR Section IX -Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section IX Summary: Narrative A Declaration of Covenant is provided for the proposed flow control BMP. There are no flow control facilities. CT ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com RECORDING REQUESTED BY AND WHEN RECORDED MAIL TO: CITY CLERK'S OFFICE CITY OF RENTON 1055 SOUTH GRADY WAY RENTON WA 98057 DECLARATION OF COVENANT FOR MAINTENANCE AND INSPECTION OF FLOW CONTROL BMPS Grantor: _____________ _ Grantee: City of Renton L ID . . THAT PORTION OF TRACT 244 INC D HILLMAN'S LAKE ega escnpt10n: __________________________ _ WASHINGTON GARDEN OF EDEN ADDITION TO SEATTLE DIVISION NO 4, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 11 OF PLATS, . . SEE BELOW Add1t1onal Legal(s) on: ________________________ _ Assessor's Tax Parcel ID#: 334390 -1606 ------------------------ IN CONSIDERATION of the approved City ofRenton(check one of the following) D residential building permit, D commercial building permit, D clearing and grading permit, D subdivision permit, or ~ short subdivision permit for Application File No. LUA/SWP ________ relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants( covenant) with City or Renton, a political subdivision of the state of Washington, that he/she(they) will observe, consent lo, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 8 below with regard to the Property. Grantor(s) hereby grants(grant), covenants( covenant). and agrees(agree) as follows: 1. Grantor(s) or his/her(their) successors in interest and assigns ("Owners") shall retain, uphold, and protect the storm water management devices, features, pathways, limits, and restrictions, known as flow control best management practices ("BMPs"), shown on the approved Flow Control BMP Site Plan for the Property attached hereto and incorporated herein as Exhibit A. 2. The Owners shall at their own cost, operate, maintain, and keep in good repair, the Property's BMPs as described in the approved Design and Maintenance Details for each BMP attached hereto and incorporated herein as Exhibit B. 3. City or Renton shall provide at least 30 days written notice to the Owners that entry on the Property is planned for the inspection of the BMPs. After the 30 days. the Owners shall allow the City of Renton to enter for the sole purpose of inspecting the BMPs. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the BMPs and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen days of receiving the City's notice of inspection. Within 30 days of giving this notice, the Owners, or the engineer on behalf of the Owners, shall provide the engineer's report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the BMPs without further notice. 4. If the City determines from its inspection, or from an engineer's report provided in accordance with Paragraph 3, that maintenance, repair, restoration, and/or mitigation work is required for the BMPs, The City shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work) required under RMC 4-6-030. The City shall also set a reasonable deadline for completing the Work or providing an engineer's report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access lo re-inspect the BMPs unless an engineer's report has been provided verifying completion of the Work. If the work is not completed properly within the time frame set by the City, the City may initiate an enforcement action. Failure to properly maintain the BMPs is a violation of RMC 4-6-030 and may subject the Owners to enforcement under the RMC 1-3, including fines and penalties. 5. Apart from perfonning routine landscape maintenance, the Owners are hereby required to obtain written approval from the City or Renton before performing any alterations or modifications to the BMPs. 6. Any notice or approval required to be given by one party to the other under the provisions of this Declaration of Covenant shall be effective upon personal delivery to the other party, or after three (3) days from the date that the notice or approval is mailed with delivery confirmation to the current address on record with each Party. The parties shall notify each other of any change to their addresses. 7. This Declaration of Covenant is intended to promote the efficient and effective management of surface water drainage on the Property, and it shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest and assigns. 8. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City of Renton that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Maintenance and Inspection of Flow Control BMPs is executed this ___ day of ___ _ ,20 GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY or KING )ss_ On this day personally appeared before me: ___________________ ,tome known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this __ day of _________ , 20 Printed name Notary Public in and for the State of Washington, residing at My appointment expires _________ _ FULL LEGAL DESCRIPTION: THAT PORTION OF TRACT 244 INC D HILLMAN'S LAKE WASHINGTON GARDEN OF EDEN ADDITION TO SEA TILE DIVISION NO 4, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 11 OF PLATS, PAGE 82, IN KING COUNTY, WASHINGTON, DESCRIBED AS FOLLOWS BEGINNING AT A POINT ON THE WEST BOUNDARY LINE OF SAID TRACT, 301 FEET SOUTH OF THE NORTHWEST CORNER OF SAID TRACT; THENCE SOUTH 64 FEET; THENCE EAST 252.3 FEET, MORE OR LESS, TO THE EAST BOUNDARY LINE OF SAID TRACT; THENCE NORTH, ALONG SAID EAST BOUNDARY LINE, 64 FEET; THENCE WEST 252.3 FEET, MORE OR LESS, TO POINT OF BEGINNING; (BEING THE NORTH 365 FEET OF SAID TRACT 244, EXCEPT THE NORTH 301 FEET THEREOF). :.0 :c >< w ····_:.:L:- l-·· ''JN ]AV NJJQ~JBV· -~ ! · .Bn1m M.l'.t,or,oos~ ·•. -....,t._ - •• "4-·-·-y•·-·--·-•-•• ' .::::, :Ji T"'~ - : i::-.:---,-- .c " C i C 0 ] <.= ·" ai > ~ en "-" OJ Cl i---N : >< in >< a 00 ' ---- ~--------""'~ MAINTENANCE INSTRUCTIONS FOR FULL INFILTRATION Your property contains an on-site BMP (besl management practice) called "full infiltration," which was installed to mitigate the storm water quantity and quality impacts of some or all of the impervious surfaces on your property. Full infiltration is a method of soaking runoff from impervious area (such as paved areas and roofs) into the ground. If properly installed and maintained per Appendix A of the City ofRenton's Surface Water Design Manual, full infiltration can manage runoff so that a majority of precipitation events are absorbed. Infiltration devices, such as gravel filled trenches, drywells, and ground surface depressions, facilitate this process by putting runoff in direct contact with the soil and holding the runoff long enough to soak most of it into the ground. To be successful, the soil condition around the infiltration device musl be reliably able to soak water into the ground for a reasonable number of years. Infiltration Devices The infiltration devices used on your property include the following as indicated on the site plan (CHECK THE BOX(ES) THAT APPLY): llllgravel filled trenches. Ddrywells, Dground surface depressions. MAINTENANCE RESTRICTIONS The size, placement, and composition of these devices as depicted by the site plan and design details must be maintained and may not be changed without written approval from the City of Renton or through a future development permit from the City of Renton. INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES • Infiltration devices must be inspected annually and after major storm events to identify and repair any physical defects. • Maintenance and operation of the system should focus on ensuring the system's viability by preventing sediment-laden flows from entering the device. Excessive sedimentation will result in a plugged or non-functioning facility. • If the infiltration device has a catch basin, sediment accumulation must be removed on a yearly basis or more frequently if necessary. • Prolonged ponding around or atop a device may indicate a plugged facility. If the device becomes plugged, it must be replaced. • Keeping the areas that drain to infiltration devices well swept and clean will enhance the longevity of these devices. • For roofs, frequent cleaning of gutters will reduce sediment loads to these devices. TYPICAL FULL INFILTRATION APPLICATIONS INFILTRATION TRENCH PLAN VIEW NTS TRENCH SETBACK FROM BUILDING AS REQUIRED, ROOF DRAIN SECTION VIEW NTS 15' MIN ~~RFLOW--i FINE MESH SCREEN , SPLASH BLOCK , 1 ~l r-_J_ 11,"-t--_ I 1'MINL 1JL.J--_cJ 1' ilN. \ -· SETBACK -- FROM BUILDING S"MIN CB SUMP w/SOLID LID COMPACTED BACKFILL FILTERFABR!C 4" RIGID OR 6'" FLEXIBLE PERFORATED ?IPE 1j··. 3"· WASHED ROCK MIN 1' ABOVE SEASONAL I 24 , _ I HIGH GROUNDWATER r----~ ROOF DC'IV'ISPOVT :JVERFLOW sn.J>SH BLOCK ~ F\OW J 5-Ml~ SETBACK. F~OM BUILDING -j I FINE MESH SCH~~N I ' CATCH SA$'N iYARD DRAIN) TABLE, SEE SECTION C2 22 !- M!\Ri<(;ENTEROFHOLE. IMTH1"CAPPEOPIIC OR OTHER MEAN~ FLUSH WITH SU'lFAC~ \ TOPSOIL MIN 4"01A. PVC PIPE SlllES OF HOL~ clNED'MTH I'll.TE~ FABRIC ' i _, ~(i~(>' l·-· -· -~· ~ 48.INCH DIAMETER VARIES ""' 0 '.HOlE FILLED \NITII 1,t--3"WASHED 't DRAIN ROCK 4 __ .s_• "_"_AS RHlUlREO, SEE SECllON C _[_ MIN. 1' AOOVE SEAsONAL HIG~ GROUSOWAl EH fA0.E, SEE SECTION C 2 l l , - SECTION NT$ T SECTION A NTS GRASS M[N.1'AB0VE I SEASONAL HIGH I 2' MIN GROUNDWATER ----e TABLE, SEE SECTION C.2.2.2 FROM ROOF \ FILTER STRIP SEE SECTIONS 634&635 X~SECTION NTS NOTE_: SEE C.2 2.3 FOR TRENCH LENGTHS, TRENCH SPACING AND SITE LIMITATIONS BOND QUANTITY WORKSHEET INSTRUCTIONS --------Kenton e Planning Division / 1055 South Grady Way-6th Floor/ Renton, WA 98057 (425) 430-7200 Community & Economic Development This worksheet is intended to be a "working" copy of the bond quantity worksheet, which will be used throughout all phases of the project, from initial submittal to project close-out approval. Submit this workbook, in its entirety, as fallows: • (1) electronic copy (.x!sx format) and (1) hard copy of the entire workbook for civil construction permit submittal. Hard copies are to be included as part of the Technical Information Report (Tl R). • (1) electronic copy (.xlsx format) and (1) hard copy of the entire workbook for final close-out submittal. The following forms are to be completed by the engineer/developer/applicant as applicable to the project: Section I: Project Information • This section includes all pertinent information for the project • This section must be completed in its entirety • Information from this section auto-populates to all other relevant areas of the workbook Section II: Bond Quantities Worksheets • Section II contains a separate spreadsheet TAB for each of the following specialties: • Section II.a EROSION CONTROL (Stabilization/Erosion Sediment Control (ESC)) • Section 11.b TRANSPORTATION (Street and Site Improvements) • Section 11.c DRAINAGE (Drainage and Stormwater Facilities): • Section 11.d WATER -ONLY APPUCABLE IF WATER SERVICE IS PROVIDED BY CITY OF RENTON • Section 11.e SANITARY SEWER -ONLY APPLICABLE IF SEWER SERVICE IS PROVIDED BY CITY OF RENTON • Complete the 'Quantity' columns for each of the appropriate section(s). Include existing Right-of-Way (ROW), Future Public Improvements and Private Improvements. • Note: Private improvements, with the exception of stormwater facilities, are not included in the bond amount calculation, but must be entered on the form. Stormwater facilities (public and private) are required to be included in the bond amount. • The 'Quantity Remaining' column is only to be used when a project is under construction. The City allows one (1) bond reduction during the life of the project with the exception of the maintenance period reduction. • Excel will auto-calculate and auto-populate the relevant fields and subtotals throughout the document. Only the 'Quantity' columns should need completing. • Additional items not included in the lists can be added under the "write-in" sections. Provide a complete description, cost estimate and unit of measure for each write-in item. • All unit prices indude labor, equipment, materials, overhead and profit. The Bond Worksheet form will auto-calculate and auto-populate from the information provided in Section I and Section II. Page 1 of 14 Section Ill. Bond Worksheet • This section calculates the required Permit Bond for construction permit issuance as well as the required Maintenance Bond for project close-out submittals to release the permit bond on a project. Unit Prices Updated: 06/14/2016 Version: 02/09/2017 SITE IMPROVEMENT BOND QUANTITY WORKSHEET ·R tCITY OF ~ PROJECTINFORMATION en on~ Planning Division / 1055 South Grady Way-6 1 h Floor/ Renton, WA 98057 (425) 430-7200 Community & Economic Development Date Prepared· [2/16/2017 Prepared by: Name: Greg Guillen PE Registration No: PE Registration No. Firm Name: CG Engineering Firm Address: 250 4th Aves, Suite 200 Phone No. 425.778.8500 Email Address: grego@cgengineering.com Project Location and Description Project Name: Aberdeen Avenue Short Plat CED Plan# (LUA): LUA 16-000967 CED Permit# (U): ######## Site Address: 1824 Aberdeen Ave NE Street Intersection: Aberdeen Ave NE and NE 20th St Parcel #(s): 3343901606 Abbreviated Legal HILLMAN$ LK WN GARDEN OF EDEN It 4 S 54 FT OF N 365 FT Description: Clearing and Grading Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No: IND I If Yes, Provide Forest Practice Permit#: IN/A 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 Page 2 of 14 Project Phase 1 [FOR APPROVAL Engineer Stamp Required (all cost estimates must have original wet stamp and signature) Project Owner Information Project Owner: Prime Metropolis Properties, Inc. Phone: 415. 731.0303 Address: 950 Taraval St. San Francisco, CA 94116 Addt'I Project Owner: Additional Project Owner Phone: Phone Address: Address City, State, Zip Utility Providers Water Service Provided by: I CITY OF RENTON Sewer Service Provided by: I CITY OF RENTON Unit Prices Updated: 06/14/2016 Version: 02/09/2017 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 SWDM 5.4.6.3 80.00 Catch Basin Protection ESC-3 35.50 Crushed surfacing 11/4" minus ESC-4 WSDDT 9-03.9/3) 95.00 Ditching ESC-5 9.00 Excavation-bulk ESC-6 2.00 Fence, silt ESC-7 SWDM 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 0.50 Hydroseeding ESC-11 SWDM 5.4.2.4 0.80 Interceptor Swale/ Dike ESC-12 1.00 Jute Mesh ESC-13 SWDM 5.4.2.2 3.50 level Spreader ESC-14 1.75 Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 2.50 Mulch, by machine, straw, 2" deep ESC-16 SWDM 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 SWDM 5.4.2.3 4.00 Rip Rap, machine placed; slopes ESC-21 WSDOT9-13.1/2) 45.00 Rock Construction Entrance, SO'xlS'xl' ESC-22 SWDM 5.4.4.1 1,800.00 Rock Construction Entrance, 100'x1S'x1' ESC-23 SWDM 5.4.4.1 3,200.00 Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 2,200.00 Sediment trap, S' high berm ESC-25 SWDM 5.4.5.1 19.00 Sed. trap, S' high, riprapped spillway berm section ESC-26 5WDM 5.4.5.1 70.00 Seeding, by hand ESC-27 SWDM 5.4.2.4 1.00 Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 8.00 Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 10.00 TESC Supervisor ESC-30 > 110.00 Water truck, dust control ESC-31 SWDM 5.4.7 5 140.00 Unit WRITE-IN-ITEMS Reference# Price Unit C'( 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 EROSION/SEDIMENT SUBTOTAL: SALES TAX@ 9.5% EROSION/SEDIMENT TOTAL: Page 3 of 14 (A) Quantity Cost 130 845.00 6 213.00 5 10.00 390 585.00 30 45.00 600 2AOO.OO 600 4,800.00 Quantity Cost 8,898.00 845.31 9,743.31 (A) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 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) (C) I No. I Unit Price Unit Quant. I Cost Quant. I Cost Gl-1 $ 6.00 CY Gl-2 $ 9.00 CY Gl-3 $ 1.00 SY Gl-4 $ 240.74 Each GI-S $ 452.34 Each Gl-6 $ 10,000.00 Acre Gl-7 $ 2.00 CY Gl-8 $ 5.00 CY 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 Gl-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 Gl-21 $ 250.00 Each 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 Surveying, lot location/lines Gl-25 $ 1,800.00 Acre 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 Gi-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 )Bl (C] Page 4 of 14 Private Improvements [DI Quant. Cost I )DI Quantity Remaining {Bond Reduction) [El Quant. I Cost I (El Unit Prices Updated: 06/14/2016 Version: 02/09/2017 I SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit#:######## Existing Future Public Right-of-Way Improvements (8) ICJ Description I No. Unit Price Unit Quant. I Cost Quant. I 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 & Gutter, rolled Rl-7 $ 17.00 LF Curb & Gutter, vertical Rl-8 $ 12.50 LF 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 Sawcut, concrete, per 1" depth Rl-13 $ 3.00 LF Sealant, asphalt Rl-14 $ 2.00 LF Shoulder, gravel, 4" thick Rl-15 $ 15.00 SY Sidewalk, 4" thick Rl-16 $ 38.00 SY 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 $ a.so LF Additional 2.5" Crushed Surfacing Rl-24 $ 3.60 SY HMA 1/2" Overlay LS" Rl-25 $ 14.00 SY HMA 1/2" Overlay 2" Rl-26 $ 18.00 SY 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 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 -· .. - (B) (C) Page 5 of 14 Private Improvements /D) Quant. Cost I (D) Quantity Remaining (Bond Reduction) IE) Quant. Cost (E) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS CED Permit#;######## Description No. I Unit Price I Unit 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 LANDSCAPING & VEGETATION No. Street Trees LA-1 Median Landscaping LA-2 Right-of-Way Landscaping LA-3 Wetland landscaping lA-4 -· ·----·· . ···---· -···--. ·----·-·-·· TRAFFIC & LIGHTING No. Signs TR-1 Street Light System { # of Poles) TR-2 Traffic Signal TR-3 Traffic Signal Modification TR-4 WRITE-IN-ITEMS § § SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL: Page 6 of 14 SALES TAX@ 9.5% STREET AND SITE IMPROVEMENTS TOTAL: Existing Future Public Right-of-Way Improvements (8( (CJ Quant. I Cost Quant. I Cost I I (Bl (Cl I I I (Bl (Cl I I (Bl (Cl (Bl (Cl Private Improvements ID) Quant. Cost I (DJ (DI (DI (DI Quantity Remaining (Bond Reduction) IE) Quant. Cost (EJ (EJ [EJ [El Unit Prices Updated: 06/14/2016 Version: 02/09/2017 , ' I I CED Permit #:######## Description SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Public Right-of-Way Improvements [Bl [Cl I No. Unit Price Unit Quant. I Cost Quant. I Cost Private Improvements ID) Quant. I Cost DRAINAGE fCPE -Corrull'ated Polvethvlene Pk•e N12 or EC:1uivalentl For Culvert orlces Avera11e of 4' cover was assumed. Assume nerforated PVC is same nrice as solid nine.I Access Road, R/D D-1 $ 26.DO SY +--(CBs include frame and lid} Beehive D-2 $ 90.00 Each Through-curb Inlet Framework D-3 $ 4DO.DO Each CB Type 1 D-4 $ 1,500.00 Each 2 3,000.00 CB Type IL D-5 $ 1,750.00 Each CB Type !I, 48" diameter D-6 $ 2,300.00 Each 1 2,300.00 for additional depth over 4' D-7 $ 480.00 FT 3 1,440.00 CB Type 11, 54" diameter D-8 $ 2,500.00 Each for additional depth over 4' D-9 $ 495.00 FT CB Type JI, 60" diameter D-10 $ 2,800.00 Each for additional depth over 4' D-11 $ 600.00 FT CB Type JI, 72" diameter D-12 $ 6,000.00 Each for additional depth over 4' D-13 $ 850.00 FT CB Type 11, 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" D-20 $ 150.00 Each Cleanout, PVC, 6" D-21 $ 170.00 Each 1 170.00 Cleanout, PVC, 8" D-22 $ 200.00 Each Culvert, PVC, 4" (Not allowed in ROW} 0-23 $ 10.00 LF Culvert, PVC, 6" (Not allowed in ROW} D-24 $ 13.00 LF 135 1,755.00 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, CM P, 12" D-33 $ 29.00 LF I 3,740.oo I I I 4,92s.oo I {Bl (Cl {DI Pa~e 7 of 14 u.uant1ty Kemainmg (Bond Reduction) {El Quant, I Cost {E{ Unit Prices Updated: 06/14/2016 Version: 02/09/2017 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 11 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, (PE, 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" Page 8 of 14 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Public Right-of-Way Improvements (BJ ICI No. I Unit Price I 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 , 130.00 Lf D-39 $ 190.00 LF D-40 $ 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 0-46 $ 78.00 LF D-47 $ 125.00 Lf D-48 $ 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 D-62 $ 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 (BJ !CJ Private Improvements (DI Quant. I Cost (D) u.uant1ty l\ema1n1ng (Bond Reduction) IE) Quant. I Cost (E) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 CED Permit#:######## Description DRAINAGE {Continued) Culvert, LCPE, 60" Culvert, LCPE, 72" Culvert, HDPE, 6" Culvert, HDPE, 8" Culvert, HDPE, 12" Culvert, HDPE, 15" Culvert, HDPE, 18" Culvert, HDPE, 24" Culvert, HDPE, 30" Culvert, HDPE, 36" Culvert, HDPE, 48" Culvert, HDPE, 54" Culvert, HOPE, 60" Culvert, HDPE, 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, Polypropvlene, 72" Culvert, DI, 6" Culvert, Dl, 8" Culvert, D!, 12" Culvert, DJ, 15" Culvert, Dl, 18" Culvert, DI, 24" Culvert, DI, 30" Culvert, Dl, 36" Culvert, DJ, 48" Culvert, DI, 54" Culvert, DI, 60" Culvert, DI, 72" Page 9 of 14 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Existing Future Puui1c Right-of-Way Improvements [Bl [C) I No. Unit Price Unit Quant. I Cost Quant. I Cost D-69 $ 180.00 LF D-70 $ 192.00 LF D-71 $ 42.00 LF D-72 $ 42.00 LF D-73 $ 74.00 LF D-74 $ 106.00 LF D-75 $ 138.00 LF D-76 $ 221.00 LF D-77 $ 276.00 LF D-78 $ 331.00 LF D-79 $ 386.00 LF D-80 $ 441.00 LF D-81 $ 496.00 LF D-82 $ 551.00 LF D-83 $ 84.00 LF D-84 $ 89.00 LF D-85 $ 95.00 LF D-86 $ 100.00 LF D-87 $ 106.00 LF D-88 $ 111.00 LF D-89 $ 119.00 LF D-90 $ 154.00 LF D-91 $ 226.00 LF D-92 $ 332.00 LF D-93 $ 439.00 LF D-94 $ 545.00 LF D-95 $ 61.00 LF 52 3,172.00 D-96 $ 84.00 LF D-97 $ 106.00 LF D-98 $ 129.00 LF D-99 $ 152.00 LF D-100 $ 175.00 LF D-101 $ 198.00 LF D-102 $ 220.00 LF D-103 $ 243.00 LF D-104 $ 266.00 LF D-105 $ 289.00 LF D-106 $ 311.00 LF I 3,1n.oo I (B) [Cl Private Improvements [DI Quant. I Cost IOI u.uant1ty Kema1nmg {Bond Reduction) IE) Quant. Cost I I [E) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit#:######## Existing Future Puui1c Right-of-Way Improvements IB) IC) Description I No. I Unit Price I Unit Quant. I Cost Quant. I Cost Saecialtv Drainaee Items Ditching SD-1 $ 9.50 CY Flow Dispersal Trench (1,436 base+) SD-3 s 28.00 LF French Drain (3' depth) SD-4 s 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" 50-8 $ 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} SD-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: I I I fBI /Cl STORMWATER FACILITIES llnclude Flow Control and Water oualit, Facilitv Summarv Sheet and Sketch I 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 Each Sand Filter SF-12 Each Sand Filter Vault Sf-13 Each Linear Sand Filter Sf-14 Each Stormfilter SF-15 $ 5,500.00 Each Rain Garden Sf-16 Each I I I (B) ICI PaRe 10 of 14 Private Improvements ID) Quant. I Cost I I I ID\ 1 5,500.00 I I s,soo.oo I (DJ uuant1ty Kemain1ng fBond Reduction) IE) Quant. I Cost I '" I I IE) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES CED Permit#:######## Existing Future Puo1ic Right-of-Way Improvements (B) (Cl 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 Wl-14 Wl-15 I I I DRAINAGE AND STORMWATER FACILITIES SUBTOTAL: I 3,740.00 1 SALES TAX @ 9.5% I 3ss.3o I DRAINAGE AND STORMWATER FACILITIES TOTAL: I 4,09s.30 1 (B) (Cl Pai;:e 11 of 14 Private Improvements ID\ Quant. Cost I I 10,42s.oo 1 I 990.38 I I 11,41s.3s 1 ID) L.1.Uant1ty r-;emammg (Bond Reduction} IE) Quant. Cost I (E) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 , SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR WATER CED Permit#:######## Description No. Connection to Existing Watermain W-1 Ductile Iron Watermain, CL 52, 4 Inch Diameter W-2 Ductile Iron Watermain, Cl 52, 6 Inch Diameter W-3 Ductile Iron Watermain, CL 52, 8 Inch Diameter W-4 Ductile Iron Watermain, CL 52, 10 Inch Diameter W-5 Ductile Iron Watermain, CL 52, 12 Inch Diameter W-6 Gate Valve, 4 inch Diameter W-7 Gate Valve, 6 inch Diameter W-8 Gate Valve, 8 Inch Diameter W-9 Gate Valve, 10 Inch Diameter W-10 Gate Valve, 12 Inch Diameter W-11 Fire Hydrant Assembly W-12 Permanent Blow-Off Assembly W-13 Air-Vac Assembly, 2-lnch Diameter W-14 Air-Vac Assembly, 1-lnch Diameter W-15 Compound Meter Assembly 3-inch Diameter W-16 Compound Meter Assembly 4-inch Diameter W-17 Compound Meter Assembly 6-inch Diameter W-18 Pressure Reducing Valve Station 8-inch to 10-inch W-19 Page 12 of 14 Unit Price Unit $ 2,000.00 Each $ SO.DO LF $ 56.00 LF $ 60.00 LF $ 70.00 LF $ 80.00 LF $ 500.00 Each $ 700.00 Each $ 800.00 Each $ 1,000.00 Each $ 1,200.00 Each $ 4,000.00 Each $ 1,800.00 Each $ 2,000.00 Each $ 1,500.00 Each $ 8,000.00 Each $ 9,000.00 Each $ 10,000.00 Each $ 20,000.00 Each ····----··----·· SALES TAX@ 9.5% WATER TOTAL: Ex1st1ng Future Puo11c Right-of-Way Improvements (B) (CJ Quant. Cost Quant. Cost 1 2,000.00 I 2,000.001 190.00 J 2,190.00 I (B) (CJ Private Improvements (0) Quant. Cost I (O) Quantity Remaining (Bond Reduction) IE) Quant. Cost I I (E) Unit Prices Updated: 06/14/2016 Version: 02/09/2017 I SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR SANITARY SEWER CED Permit#:######## Description Clean Outs Grease Interceptor, 500 gallon Grease Interceptor, 1000 gallon Grease Interceptor, 1500 gallon Side Sewer Pipe, PVC. 4 Inch Diameter Side Sewer Pipe, PVC. 6 Inch Diameter Sewer Pipe, PVC, 8 inch Diameter Sewer Pipe, PVC, 12 Inch Diameter Sewer Pipe, DI, 8 inch Diameter Sewer Pipe, DI, 12 Inch Diameter Manhole, 48 Inch Diameter Manhole, 54 Inch Diameter Manhole, 60 Inch Diameter Manhole, 72 Inch Diameter Manhole, 96 Inch Diameter Pipe, C-900, 12 Inch Diameter Outside Drop Inside Drop Sewer Pipe, PVC, Inch Diameter lift Station (Entire System1 Page 13 of 14 No. Unit Price Unit SS-1 $ 1,000.00 Each 55-2 $ 8,000.00 Each 55-3 $ 10,000.00 Each 55-4 $ 15,000.00 Each 55-5 $ 80.00 LF 55-6 $ 95.00 LF 55-7 $ 105.00 LF 55-8 $ 120.00 LF 55-9 $ 115.00 LF 55-10 $ 130.00 LF SS-11 $ 6,000.00 Each 55-13 $ 6,500.00 Each 55-15 $ 7,500.00 Each SS-17 $ 8,500.00 Each 55-19 $ 14,000.00 Each 55-21 $ 180.00 LF 55-24 $ 1,500.00 LS 55-25 $ 1,000.00 LS 55-26 55-27 LS C ... tdlT ... DV CLIAILD Cl IDTf"\T"I, SALES TAX@ 9.5% SANITARY SEWER TOTAL: Ex1st1ng Right-of-Way (B( Quant. 40 I Cost 3,800.00 3,soo.oo I 361.00 J 4,161.00 J (Bl Future Puo11c Improvements (C) Quant. Cost IC) - Private u.uanc1 y "ema1n1ng Improvements (Bond Reduction) ID) Quant. 2 130 I (E) Cost Quant. Cost 2,000.00 12,350.00 14,3so.oo 1 I 1,363.2s J 1s,113.2s J (DI {El Unit Prices Updated: 06/14/2016 Version: 02/09/2017 ..,_....-CITY OF e SITE IMPROVEMENT BOND QUANTITY WORKSHEET Renton ~ BOND CALCULATIONS Planning Division / 1055 South Grady Way-6:n Floor/ Renton, WA 98057 (425) 430-7200 Date: 2/16/2017 Prepared by: Name: Greg Guillen Project Name: PE Registration No: PE Registration No. CED Plan# (LUA): Firm Name: CG Engineering CED Permit# (U): Firm Address: 250 4th Ave S, Suite 200 Site Address: Phone No. 425.778.8500 Parcel tt(s): Email Address: grego@cgengineering.com Project Phase: CONSTRUCTION BOND AMOUNT•;•• {prior to permit issuance) Site Restoration/Erosion Sediment Control Subtotal (al 1$ 9,743.31 I Existing Right-of-Way Improvements Subtotal (bl 1$ 6,1s1.oo I Future Public Improvements Subtotal Stormwater & Drainage Facilities (Public & Private) Subtotal (di 1$ 15,510.681 Bond Reduction: f)(isting Right-of-Way Improvements (Quantity (e) Is -I Remaining) 2 Bond Reduction: Stormwater & Drainage Facilities (Quantity If! I$ -I Remaining) 2 Site Restoration p (a) X 100% 1$ 9,743.31 I Civil Construction Permit R ((bx 1SD%) + Id x 100%1) 1$ 25,037.181 Maintenance Bond Bond Reduction 2 s I$ I - (e) x 150% +{!}"JOO% Construction Permit Bond Amount 3 T 1$ 34,780.491 (P+R-5) Mimmum [)orrd Amourit is $10,000.00 'Estimate Only -May involve multiple and variable componi>nt~. which will be established on an individual basi; by Development En~ineering Community & Economic Development Project Information Aberdeen Avenue Short Plat LUA 16-000967 ##ffff#ff## 1824 Aberdeen Ave NE 3343901606 FOR APPROVAL MAINTENANCE BOND'/ .. {after final acceptance of construction) (b) 1$ 6,351.00 I (cl I$ -I (di 1$ 15,510.681 EST 1 1$ 4,372.341 l(b) + (c) + (d)l X 20% 'The City of Renton allows one request onlv for bond redudion prior to the ma1menancr> 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 3 Required l>ond Amounts are subject to review and mo'11ficat1on by D!'V!'lopment ~ng1neenng. • Note: The word BOND as used in this noci1ment means any financial guarantee accepto1ble to the City of Renton. _. Note: All pr[rf>s include labor, equipment, materials, overhe..id and profit Unit Prices Updated: 06/14/2016 1/n-,;~~· rnlnchn, 7 Aberdeen Ave Subdivision 16037.20 Technical Information Report February 16, 2017 Section X, Page 1 TIR Section X -Operation and Maintenance Manual TIR Section X Summary: Narrative Maintenance instructions for the proposed flow control BMP is included in the Declaration of Covenant found in Section IX with a proposed Flow Control BMP site plan. Please note that the site plan is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as-built drawings are completed for the site. The project contractor will be responsible for passing along the information in this maintenance manual to the owner. Upon request by the City, it shall be made available for their inspection. Facilities shall be inspected for defects. The frequency of this should occur annually. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. c::::: ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com 4 • + civil & structural ENGINEERING 250 4th Ave s Ste 200 Edmonds, WA 98020 Phone: {425) 778-8500 Fax: (425) 778-5536 engineering & planning TECHNICAL INFORMATION REPORT Aberdeen Ave Subdivision 1824 Aberdeen Ave NE Renton, WA 98056 12/15/2016 CG Project No. 16037.20 Table of Contents Tl R Section I -Project Overview TIR Section II -Conditions and Requirements Summary TIR Section Ill -Off Site Analysis TIR Section IV -Flow Control and Water Quality Facility Analysis and Design TIR Section V -Conveyance System Analysis and Design TIR Section VI -Special Reports and Studies TIR Section VII -Other Permits TIR Section VIII -CSWPPP Analysis and Design TIR Section IX -Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section X-Operation and Maintenance Manual CT? ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425. 778.8soo I t. 425. 778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report TIR Section I Summary Narrative TIR Section I -Project Overview List of Figures: 1. TIR Worksheet 2. Site Location 3. Aerial Photograph Map December 15, 2016 Section I, Page 1 4. Site Drainage, Drainage Basins, Sub-basins, and Site Characteristics 5. Soils The project proposes to subdivide a single 16,161 sf parcel in the R-8 zone into 2 individual single-family lots. The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The project will add more than 2,000 sf of impervious surfaces and will therefore address Full Drainage requirements from the 2016 King County Surface Water Design Manual. Lots 1 and 2 will be developed in the future. Stormwater requirements are addressed as part of this project for the driveway tract and for the future lots. Address; 1824 Aberdeen Ave NE, Renton, WA 98056 Tax Parcel Number: 334390-1606 The existing lot will be divided as follows: Proposed Short Plat Coverage Lot 1: 5,677 sf (0.130 ac) Lot 2: 7,903 sf (0.181 ac) Tract: 2,581 sf 10.059 ac) Total: 16,128 sf (0.370 ac) Flow Control per Core Requirement #3 must be evaluated for this site because over 5,000 sf of new plus replaced impervious surface will be created. The project falls within the City's Flow Control Duration Standard (Forested Conditions). However, the project is exempt from the facility requirement because there is no more than a 0.1-cfs difference (when modeled using 1 hour time steps) in the 100-year peak flow. Please see Section IV for the Western Washington Hydrology Model report and assumptions. Flow Control Best Management Practices (BMPs) must be addressed per Core Requirement #9 to mitigate stormwater runoff impacts because the site adds and/or replaces more than 2,000 square feet of impervious surface. Flow Control BMPs were evaluated for the access/utility tract per Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement BMP Requirements) and for the individual lots per Section 1.2.9.2.1 "Small Lot BMP Requirements." A single infiltration trench is proposed to meet the requirements for the access/utility tract and for both lots. Please see Section IV for the infiltration trench sizing and assumptions. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425. 778.8500 I t. 425. 778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 December 15, 2016 Technical Information Report Section I, Page 2 ·-'----------------------------'-----''-- Figure 1-1: Technical Information Report (TIR) Worksheet See attached pages. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425.778.5536 www.cgengineering.com KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner Prime Metropolis Properties, Inc. Phone 925.377.8882 Address 950 Taraval St. San Francisco, CA 94116 Project Engineer Jared Underbrink Company CG Engineering Phone 425.778.8500 Part 3 TYPE OF PERMIT APPLICATION D Landuse (e.g.,Subdivision / Short Subd. / UPD) 0 Building (e.g.,M/F /Commercial/ SFR) 0 Clearing and Grading 0 Right-of-Way Use ~ Other Land Use Permit Master Application Part 5 PLAN AND REPORT INFORMATION Technical Information Report ~ Full Type of Drainage Review D Targeted (check one): D Simplified D Large Project Date (include revision D Directed dates): Date of Final: Part 6 SWDM ADJUSTMENT APPROVALS Part 2 PROJECT LOCATION AND DESCRIPTION Project Name Aberdeen Subdivision DPER Permit# ---------- Location Township ----=2,,_3 ___ _ Range -----'5'-------- Section __ 5 ____ _ Site Address 1824 Aberdeen Ave NE Renton, WA 98056 Part4 OTHER REVIEWS AND PERMITS D DFWHPA D Shoreline D COE404 Management D DOE Dam Safety D Structural RockeryNault/ __ D FEMA Floodplain D ESA Section 7 D COE Wetlands D Other Site Improvement Plan (Engr. Plans) Plan Type (check [I Full one): D Modified D Simplified Date (include revision dates): Date of Final: Type (circle one): Standard / Experimental I Blanket Description: (include conditions in TIR Section 2) Approved Adjustment No. Date of Approval: 2016 Surface Water Design Manual 1 4/2412016 KING COCNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET . Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION/ SITE CONSTRAINT D Core 2 -Offsite Analysis D Sensitive/Critical Areas D SEPA D LID Infeasibility D other D D Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: Total Site (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: 1 Offsite Analysis Level: CD 2 , 3 dated: 01/20/16 Flow Control (include facility Level: 1 (D 3 or Exemption Number 2 summary sheet) Flow Control BMPs Infiltration Trench Conveyance System Spill containment located at: Erosion and Sediment Control/ CSWPP/CESCUESC Site Supervisor: Construction Stormwater Pollution Prevention Contact Phone: After Hours Phone: Maintenance and Operation Responsibility (circle one): ~/ Public If Private, Maintenance Log Required: Yes@ Financial Guarantees and Provided: Yes@ Liability Water Quality (include facility Type (circle one)~ Sens. Lake / Enhanced Basic / Bog summary sheet) or Exemption No. SURFACE EX. "a" Landscape Management Plan: Yes@ Special Requirements (as applicable): Area Specific Drainage Type: CDA I SDO I MOP/ BP/ LMP / Shared Fae. /~ Requirements Name: Floodplain/Floodway Delineation Type (circle one): Major I Minor I Exemption /~ 1 DO-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: 2016 Surface Water Design Manual 3 4/24/2016 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN 'V!ANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTSffRACTS Part 16 STRUCTURAL ANALYSIS 0 Drainage Easement D Cast in Place Vault l:EJ Covenant 0 Retaining Wall 0 Native Growth Protection Covenant 0 Rockery> 4' High 0 Tract 0 Structural on Steep Slope 0 Other 0 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 information videol;r e is accurate. . J /2 /5 h Signed/Date 4/24/2016 2016 Surface Water Design Manual 5 Aberdeen Ave Subdivision 16037.20 Tec hnica l Information Report !J %;'1S1 'l :-i 'ilh <;1 N:.W.t,•;. '>I .B r n f'I N.:'h)Sl Gene Coulon Memorial Beach Park The Land ing Ii!) ,, 'f'• + ENGINEERING ,• ~; r ;;· n 0 5 r-J[ ;.,71:1 St ~-CT I~ a. ';tl St-::, SE 881 11 St z n May Creek Parl< .. ~ 111 1824 Aberdun Avenue Northeast -< ~< °c. I\,[ p ·/'r· ; 1,. :!. 7- cil Fry 's Ele ct ron ics ,1 -- 7.' 3 0 :., :>. " t :o z Figure 1-2 : Site Location December 15, 2016 Section I, Page 3 '• -:.: "' 'f.:. s _ !l ~th 51 t~E f!t li Sl Sa- c: :• ;, ,· "' z ,.... 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph . 42S .778.8soo I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Info rm at ion Report • ENGINEERING Figure 1-3: Aerial Photograph December 15, 2016 Section I, Page 4 25 0 4th Aven ue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t . 425.778.5536 www.cgengineering .com Aberdeen Ave Subdivision 16037.20 Technical Information Report ;z -!t < N l~th St3.: z ~ _gl·l _33.rd S t . 4 N 32nd St ,;;: u 3 1St s.t E N 30tli Sf aj l~_?Pt h St ~ "t_ROJECT SITE ~ . Wat ershed n ame: O' \ I ' ' 21 C> 'I, ENGINEERING \ N.t 2 cth .SI <[ NE l &h St WR IA numb;;r: WRLA r ami:: ME J~th St ~ 'f 7rh Sr 4-1: 6L~ I'/ Highl a nd s Park ,Renton Figure 1-4 : Drainage Basin Map December 15, 2016 Section I, Page 5 Moy ere Open Spa Cedar River/ Lake Washington -t th St 8 Cedar-Sammamish 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph . 425.778.8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subd ivision 16037.20 Technical I nfo r mat ion Report Figure 1-5: Soils December 15, 2016 Section I, Page 6 Unde r lying soi ls were determ i ned us i ng t he Natu r al Resources Conservation Service soil survey tool. The site contains Indiano la loamy sa nd , S to 15%, corr es ponding to hydro logic so il group "A." A geotechnical repo r t w ith a recommended infiltration rate is also provided in Section VI. See attached pages. 4 ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425 .778.5536 www.cgengineeri ng.com . .. . . . ' . . . ... .. . . ... . . . . .... .t• I -..... • .t• I ..... .1• I ..... -..... . ... •It .' ... .. ,- . . -- ' ~ .-. . ,,_._ ... · .. ·' , ... ··~· I ~~ ~--: . ..j .. ~ .:.._. . . ~ W! o u.a d( -. • -~ .. O T •lill .. : )> ]~--i a • _,, • • -., ~ I -- g-( I ~ ' , ' t ;. '· -I : ; U... lnC • ~ • . . ·__ ------~---~--------·-----__ )? . • • . --~ ...... ' I ,. ~-r j, .... •• • ~ I . .. . ··-..... . ,. . . .... . ,. . --. .... . . ... . ... • 0 r. • •• I ,l',t ,t• I '·" ,. . ..... . -. . .. , n • • ... ... . ... ! • • ... ,. 1 • • • ••• I :;. r.. • . .. ••• • ,. :... • • •• •· t-.: I t ' . I :• . . . I • . . .. . ... . ..... " . •fa f Soil MaJ}--King County Area, Washington (Aberdeen Ave Subdivision) MAP LEGEND Area of Interest (AOI) Soils LJ -.,, • Area af Interest (AO!) Soil Map Unit Polygons Soil Map Unit lines Soil Map Unit Points Special Point Features 12' Blowout 181 Borrow Pit )( Clay Spot ' '·/ Closed Depression X Gravel Pit Gravelly Spot 0 Landfill A. Lava Flow ..i. Marsh or swamp 11: Minear Quarry @ Miscellaneous Water Q Perennial Water "' Rock Outcrop + Saline Spot Sandy Spot @ Severely Eroded Spot 0 Sinkhole i>· Slide or Slip fJ Sadie Spot USDA Natural Resources :iilia Conservation Service a Spoil Area ;) Stony Spot (h Very Stony Spot 17 Wel Spot Ll Other .. Special Line Features Water Features Streams and Canals Transportation t-+-t Rails ...... Interstate Highways US Routes Major Roads Local Roads Background • Aerial Photography Web Soil Survey National Cooperative Soil Survey MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1 :24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Survey Area Data: King County Area, Washington Version 11, Sep 14, 2015 Soil map units are labeled (as space allows) for map scales 1 :50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013--0ct 6, 2013 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 11/7/2016 Page 2 of3 Soil Map-King County Area, Washington Map Unit Legend Map Unit Symbol lnC Totals for Area of Interest USDA Natural Resources -Conservation Service King County Area, Washington (WA633) Map Unit Name Acres in AOI Indianola loamy sand, 5 to 15 percent slopes -- Web Sail Survey National Cooperative Soil Survey -- 0.8 0.8 Aberdeen Ave Subdivision Percent of AOI ' 100.0% j i 100.0% 11 /712016 Page 3 of3 Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section II, Page 1 TIR Section II -Conditions and Requirements Summary TIR Section II Summary Core Requirements The proposed project will comply with the 2016 King County Surface Water Design Manual as amended by the City of Renton (2016 KCSWDM). The project is being submitted for a Full Drainage Review because it proposes to add and/or replace over 2,000 square feet of impervious area. The project must comply with all 9 Core Requirements and all 5 Special Requirements. Therefore, the following conditions are required as specified by the 2016 KCSWDM. Core Requirements Core Requirement #1: Discharge at the Natural Location: Discharge will remain at the natural location and will flow from east to west. There is a public stormwater system in Aberdeen Ave NE that the site will connect into. Core Requirement #2: Offsite Analysis: Compliance with this requirement is indicated in Section Ill. Core Requirement #3: Flow Control: The site is within a Conservation Flow Control Area. However, the site is exempt from the flow facility requirement per Exception #2 of Section 1.2.3.1.B of the 2016 KCSWDM. Core Requirement #4: Conveyance System: New pipe systems shall 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. Core Requirement #5: Erosion & Sediment Control: A Construction Stormwater Pollution Prevention Plan (CSWPPP) and narrative has been prepared. See Section VIII. Core Requirement #6: Maintenance & Operations: Maintenance requirements are addressed in Section X for the flow control BMP. Core Requirement #7: Financial Guarantees & Liabilities: The project may be required to execute to the City a construction bond prior to a permit and a maintenance bond prior to acceptance. Core Requirement #8: Water Quality: Not applicable (Surface Area Exemption "a" in Volume 1, Section 1.2.8). Less than 5,000 square feet of new plus replaced pollution generating impervious surface and less than% acres of new pollution generating pervious surface are proposed. Core Requirement #9: Flow Control BMPs: This is discussed in Section IV. An infiltration trench is proposed to meet the flow control BMP requirement of this project. It was sized to fully infiltrate runoff from the assumed roof areas of Lots 1 and 2, and from the proposed road surface of the access/utility tract. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Special Requirements Special Requirement #1: Other Adopted Requirements: Not applicable. Special Requirement #2: Flood Hazard Area Delineation: Not applicable. Special Requirement #3: Flood Protection Facilities: Not applicable. December 15, 2016 Section II, Page 2 Special Requirement #4: Source Control: Permanent and temporary source Controls are discussed in Section 8 of this report. Special Requirement #5: Oil Control: Not applicable. Special Requirement #6: Aquifer Protection Area: The project is in Zone 2 of the Aquifer Protection Area. However, the project is not subject to additional requirements because neither open stormwater facilities nor open conveyance systems are proposed. cm ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I r. 425.778.5536 www .cge ngi nee ring.com Aberdeen Ave Subdivision 16037.20 Technical Information Report TIR Section Ill Summary Narrative TIR Section Ill -Off Site Analysis December 15, 2016 Section Ill, Page 3 The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The slope across the lot is downstream from east to west at an average of 4%. Adjacent lots contain single family residences. Task 1: Study Area Definition and Maps The study area is defined as the project site and the area one mile downstream (minimum flow path distance) from the proposed discharge location for the purposes ofTask 2, and is defined as the project site and a minimum of one-quarter mile downstream from the proposed discharge location for the purposes of Tasks 3, 4, and 5. The drainage basin map can be found in Figure 4 of Section 1. The site is within the East Lake Washington drainage basin. Task 2: Resource Review Drainage and water quality problems and complaints were investigated using the King County iMap website. None were found within the range of the required downstream analysis. The site does not appear to contain nor is adjacent to any environmentally sensitive areas. Task 3: Field Inspection A site visit was done the morning of 01/20/2016. There did not appear to be any existing drainage issues. As discovered in the resource review and site photographs, the area downstream from the site is heavily vegetated and steep. CT? ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Techn ica l Info rmat ion Report Figure 111-1 View of Aberdeen Ave NE looking south . Figure 111 -2 View of si te (on left) looking eas t . ENGINEERING Decem b er 15, 2016 Section Il l, Pa ge 4 250 4th Avenue South, Suite 200 Ed monds, WA 98020 ph . 425.778.8 500 I t. 425.778.553 6 www.cgengineering.com Abe rd een Ave Subdivision 16037.20 Technical Info rmation Report Figure 111-3 View of Aberdee n Ave NE looking north . Figure 111 -4 View from back of site looking west. + ENGINEERING December 15, 2016 Section Ill, Pag e 5 250 4th Avenue South, Suite 200 Edmonds, WA 9 80 20 ph. 425.778 .8500 I f. 425.778.S536 www.cgengineering .com Aberdeen Ave Subdivision 16037.20 Technical Information Report Task 4: Drainage System Description and Problem Descriptions December 15, 2016 Section Ill, Page 6 No drainage problems are expected. The existing conveyances adjacent to the site include an 18" public storm main on the western frontage of Aberdeen Ave NE. Site runoff is expected to flow in the existing condition from east to west and connect into this system. Task 5: Mitigation of Existing or Potential Problems No existing drainage problems were discovered. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425. 778.8500 I 1. 425. 778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section IV, Page 1 TIR Section IV -Flow Control and Water Quality Facility Analysis and Design TIR Section IV Summary: Narrative PART A: Existing Site Hydrology PART 8: Developed Site Hydrolagy PART C: Performance Standards PART D: Flow Control System PART E: Water Quality System WWHM2012 Report PART A: EXISTING SITE HYDROLOGY The 2012 Western Washington Hydrology Model (WWHM) was used to model flow control. Per the City of Renton's Flow Control Application Map (Reference 11-A in the King County Manual), the site is within the Flow Control Duration Standard (Forested Condition). The predeveloped land coverage is as follows: Pervious Areas Forest. Flat, A/B: Total: PART B: DEVELOPED SITE HYDROLOGY 16,128 sf {0.370 ac) 16,128 sf (0.370 ac) In the proposed condition, the existing lot will be subdivided into 2 lots and existing structures will be demolished. Impervious areas were assumed for the proposed lots according to Section 3.2 of the 2016 KCSWDM since Lot 1 and Lot 2 will be developed in the future. Per Section 3.2, the assumed impervious coverage "shall not be less than 4,000 sf per lot or the maximum impervious coverage permitted by code (K.C.C. 21A.12.030), whichever is less." The maximum impervious coverage allowed per code for the zoning (R-8) is 75%, or 4,257 sf and 5,927 sf for Lot 1 and Lot 2, respectively. The assumed impervious coverage shall be 75% and the maximum building coverage shall be 50% for the purposes of this hydrology model. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425. 778.8soo I 1. 42s. 778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037 .20 Technical Information Report The assumed developed lot coverage is as follows: Assumed Lot 1 Developed Lot Coverage Pervious Areas Landscaping. Flat. A/B: 1.420 sf (0.032 ac) Total: 1,420 sf (0.032 ac) Impervious Areas Roof, Flat: Driveway/Walkways, Flat: Total: Assumed Lot 2 Developed Lot Coverage Pervious Areas Landscaping. Flat. A/B: Total: Impervious Areas Roof, Flat: Driveway/Walkways, Flat. A/B: Total: 2,838 sf (0.065 ac) 1,976 sf {0.033 ac) 4,257 sf (0.130 ac) 1.976 sf (0.045 ac) 1,976 sf (0.045 ac) 3,951 sf (0.091 ac) 1.976 sf (0.045 ac) 5,927 sf (0.136 ac) Assumed Tract Developed Lot Coverage Impervious Areas Driveway. Flat, A/B: 2,581 sf (0.059 ac) Total: 2,581 sf (0.059 ac) December 15, 2016 Section IV, Page 2 The proposed Flow Control BMP is an Infiltration Trench per Section 5.2 of the 2016 KCSWDM. An infiltration design rate of 7.35 in/hr was determined for the site (see Section VI for the geotechnical report). The trench was sized to be 80'x5'x2' deep and will be sited in the access/utility tract. Surface water will be directed from the roofs of Lots 1 and 2, and from the access/utility tract. PART C: PERFORMANCE STANDARDS 1. Area-Specific Flow Control Facility standard: The site is within the City of Renton's Flow Control Duration Standard (Forested Conditions). 2. Flow Control BM Ps: Flow Control BMP Implementation requirements were determined from Section 1.2.9.3.1 "Small Subdivision and Urban Subdivision Projects BMP Requirements." BMPs for plat infrastructure improvements (driveway tract) were evaluated per Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement Project BMP Requirements." BMPs for the future development of the two individual lots were evaluated per Section 1.2.9.2.1 "Small Lot BMP Requirements." ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.SS36 www .cge ngi neeri ng.com Aberdeen Ave Subdivision 16037.20 Technical Information Report 3. Conveyance System Capacity Standards: December 15, 2016 Section IV, Page 3 New pipe systems shall 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. 4. Area-Specific Water Quality Treatment Menu: Lot 1, Lot 2, and the access/utility tract are evaluated individually for this requirement. Each lot meets the Surface Area Exemption of Core Requirement #8 and therefore the Area-Specific Water Quality Treatment is not required. PART D: FLOW CONTROL SYSTEM An infiltration trench is proposed to meet the flow control BMP requirement of this project. The trench will be 80' x 5' x 2' deep and will be sited within the access/utility tract. The design infiltration rate used was 7.35 in/hr per the geotechnical report found in Section VI. It was sized to fully infiltrate runoff from the assumed roof areas of Lots 1 and 2, and from the proposed road surface of the access/utility tract. BMPs must be implemented for 10% of the site/lot for sites/lots up to 11,000 sf per Section 1.2.9.2.1 "Small Lot BMP Requirements." The assumed roof area is 50% of each lot (see Part B), and should therefore meet this requirement. Runoff from all of the impervious surfaces of the access/utility tract will be infiltrated per the requirement that all target surfaces must be mitigated to the maximum extent feasible from the list in Section 1.2.9.3.2 "Small Road Improvement and Urban Road Improvement Projects BMP Requirements." The project is exempt from the facility requirement of Core Requirement #3: Flow Control per Exception #2 of Section 1.2.3.1.B of the 2016 KCSWDM because the 100-year peak flow is no more than 0.1 cfs (when modeled using 1 hour time steps). Please see the WWHM summary. The model includes the infiltration trench. PART E: WATER QUALITY SYSTEM The project does not propose a water quality system per Part C. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT General Model Information Project Name: Aberdeen Ave 12.15.16 Site Name: Aberdeen Ave Subdivision Site Address: 1824 Aberdeen Ave NE City: Renton Report Date: 12/15/2016 Gage: Seatac Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.00 Version: 2014/01/22 POC Thresholds Low Flow Threshold for POC1: High Flow Threshold for POC1: Aberdeen Ave 12.15.16 50 Percent of the 2 Year 50 Year 12/15/2016 3:47:39 PM Page 2 Landuse Basin Data Predeve/oped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use Acres A B, Forest, Flat 0.37 Pervious Total 0.37 Impervious Land Use Acres Impervious Total 0 Basin Total 0.37 Element Flows To: Surface lnterflow Aberdeen Ave 12.15.16 Groundwater 1211512016 3:47:39 PM Page 3 Mitigated Land Use Driveway Tract Bypass: No GroundWater: No Pervious Land Use Acres Pervious Total 0 Impervious Land Use Acres DRIVEWAYS FLAT 0.059 Impervious Total 0.059 Basin Total 0.059 Element Flows To: Surface lnterflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 4 Lot 1 Roof Bypass: No GroundWater: No Pervious Land Use Acres Pervious Total 0 Impervious Land Use Acres ROOF TOPS FLAT 0.065 Impervious Total 0.065 Basin Total 0.065 Element Flows To: Surface lnterflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 5 Lot 2 Roof Bypass: No GroundWater: No Pervious Land Use Acres Pervious Total 0 Impervious Land Use Acres ROOF TOPS FLAT 0.091 Impervious Total 0.091 Basin Total 0.091 Element Flows To: Surface lnterflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 6 Lot 1 and Lot 2 Runoff Bypass: Yes GroundWater: No Pervious Land Use Acres AB, Lawn, Flat 0.093 Pervious Total 0.093 Impervious Land Use Acres DRIVEWAYS FLAT 0.062 Impervious Total 0.062 Basin Total 0.155 Element Flows To: Surface lnterflow Groundwater Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 7 Mitigated Routing Gravel Trench Bed 1 Bottom Length: Bottom Width: Trench bottom slope 1: Trench Left side slope 0: Trench right side slope 2: Material thickness of first layer: Pour Space of material for first layer: Material thickness of second layer: Pour Space of material for second layer: Material thickness of third layer: Pour Space of material for third layer: Infiltration On Infiltration rate: Infiltration safety factor: Total Volume Infiltrated (ac-ft): Total Volume Through Riser (ac-ft): Total Volume Through Facility (ac-ft): Percent Infiltrated: Discharge Structure Riser Height: 1.8 ft. Riser Diameter: 18 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(ft) 0.0000 0.0222 0.0444 0.0667 0.0889 0.1111 0.1333 0.1556 0.1778 0.2000 0.2222 0.2444 0.2667 0.2889 0.3111 0.3333 0.3556 0.3778 0.4000 0.4222 0.4444 0.4667 0.4889 0.5111 0.5333 0.5556 Area(ac) 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 0.009 Volume(ac-ft) 0.000 0.000 0000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 80.00 ft. 5.00 ft. 0.001 To 1 0 To 1 0 To 1 2 0.3 0 0 0 0 7.35 1 33.254 0 33.254 100 Discharge(cfs) lnfilt(cfs) 0.000 0.000 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 0.000 0.068 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 9 0.5778 0.009 0.001 0.000 0.068 0.6000 0.009 0.001 0.000 0.068 0.6222 0.009 0.001 0.000 0.068 0.6444 0.009 0.001 0.000 0.068 0.6667 0.009 0.001 0.000 0.068 0.6889 0.009 0.001 0.000 0.068 0. 7111 0.009 0.002 0.000 0.068 0.7333 0.009 0.002 0.000 0.068 0.7556 0.009 0.002 0.000 0.068 0.7778 0.009 0.002 0.000 0.068 0.8000 0.009 0.002 0.000 0.068 0.8222 0.009 0.002 0.000 0.068 0.8444 0.009 0.002 0.000 0.068 0.8667 0.009 0.002 0.000 0.068 0.8889 0.009 0.002 0.000 0.068 0.9111 0.009 0.002 0.000 0.068 0.9333 0.009 0.002 0.000 0.068 0.9556 0.009 0.002 0.000 0.068 0.9778 0.009 0.002 0.000 0.068 1.0000 0.009 0.002 0.000 0.068 1.0222 0.009 0.002 0.000 0.068 1.0444 0.009 0.002 0.000 0.068 1.0667 0.009 0.002 0.000 0.068 1.0889 0.009 0.003 0.000 0.068 1.1111 0.009 0.003 0.000 0.068 1.1333 0.009 0.003 0.000 0.068 1.1556 0.009 0.003 0.000 0.068 1.1778 0.009 0.003 0.000 0.068 1.2000 0.009 0.003 0.000 0.068 1.2222 0.009 0.003 0.000 0.068 1.2444 0.009 0.003 0.000 0.068 1.2667 0.009 0.003 0.000 0.068 1.2889 0.009 0.003 0.000 0.068 1.3111 0.009 0.003 0.000 0.068 1.3333 0.009 0.003 0.000 0.068 1.3556 0.009 0.003 0.000 0.068 1.3778 0.009 0.003 0.000 0.068 1.4000 0.009 0.003 0.000 0.068 1.4222 0.009 0.003 0.000 0.068 1.4444 0.009 0.004 0.000 0.068 1.4667 0.009 0.004 0.000 0.068 1.4889 0.009 0.004 0.000 0.068 1.5111 0.009 0.004 0.000 0.068 1.5333 0.009 0.004 0.000 0.068 1.5556 0.009 0.004 0.000 0.068 1.5778 0.009 0.004 0.000 0.068 1.6000 0.009 0.004 0.000 0.068 1.6222 0.009 0.004 0.000 0.068 1.6444 0.009 0.004 0.000 0.068 1.6667 0.009 0.004 0.000 0.068 1.6889 0.009 0.004 0.000 0.068 1. 7111 0.009 0.004 0.000 0.068 1.7333 0.009 0.004 0.000 0.068 1.7556 0.009 0.004 0.000 0.068 1.7778 0.009 0.004 0.000 0.068 1.8000 0.009 0.005 0.000 0.068 1.8222 0.009 0.005 0.000 0.068 1.8444 0.009 0.005 0.000 0.068 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 10 1.8667 0.009 0.005 0.000 0.068 1.8889 0.009 0.005 0.000 0.068 1.9111 0.009 0.005 0.000 0.068 1.9333 0.009 0.005 0.000 0.068 1.9556 0.009 0.005 0.000 0.068 1.9778 0.009 0.005 0.000 0.068 2.0000 0.009 0.005 0.000 0.068 Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 11 Analysis Results POC 1 ,oo I 000 f-----1-------------- ~ 000 IL ooo 0.0010E-5 000 ;; £ 0.00 ~ 000 J IL ,oo 1CE-4 10E·3 lOE-2 lOE-1 r ... .-c.,.nt Tim ... Ex.c: ... ..,din9 rn w + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.37 Total Impervious Area: O Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.093 Total Impervious Area: 0.277 Flow Frequency Method: Log Pearson Type Ill 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000314 5 year 0.000475 10 year 0.000606 25 year 0.000803 50 year 0.000975 100 year 0.00117 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.024159 5 year 0.031687 10 year 0.037171 25 year 0.044689 50 year 0.050732 100 year 0.057169 Annual Peaks Aberdeen Ave 12.15.16 12/15/2016 3:47:39 PM Page 12 Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.031 1950 0.001 0.034 1951 0.001 0.022 1952 0.000 0.017 1953 0.000 0.018 1954 0.000 0.020 1955 0.000 0.022 1956 0.000 0.021 1957 0.000 0.024 1958 0.000 0.020 1959 0.000 0.020 1960 0.000 0.020 1961 0.000 0.021 1962 0.000 0.018 1963 0.000 0.021 1964 0.000 0.020 1965 0.000 0.026 1966 0.000 0.017 1967 0.000 0.032 1968 0.000 0.033 1969 0.000 0.023 1970 0.000 0.022 1971 0.000 0.026 1972 0.002 0.033 1973 0.000 0.016 1974 0.000 0.024 1975 0.000 0.028 1976 0.000 0.019 1977 0.000 0.020 1978 0.000 0.025 1979 0.000 0.034 1980 0.000 0.030 1981 0.000 0.025 1982 0.000 0.035 1983 0.000 0.028 1984 0.000 0.018 1985 0.000 0.025 1986 0.000 0.021 1987 0.000 0.033 1988 0.000 0.020 1989 0.000 0.025 1990 0.000 0.061 1991 0.000 0.039 1992 0.000 0.018 1993 0.000 0.015 1994 0.000 0.017 1995 0.000 0.022 1996 0.002 0.029 1997 0.000 0.025 1998 0.000 0.023 1999 0.000 0.047 2000 0.000 0.023 2001 0.000 0.026 2002 0.000 0.030 2003 0.000 0.024 2004 0.000 0.044 Aberdeen Ave 12.15.16 12/15/2016 3:48:44 PM Page 13 2005 2006 2007 2008 2009 0.000 0.000 0.003 0.000 0.000 Ranked Annual Peaks 0.020 0.020 0.060 0.038 0.031 Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0031 0.0609 2 0.0021 0.0596 3 0.0015 0.0470 4 0.0006 0.0439 5 0.0006 0.0386 6 0.0005 0.0377 7 0.0005 0.0348 8 0.0003 0.0337 9 0.0003 0.0336 10 0.0003 0.0330 11 0.0003 0.0330 12 0.0003 0.0328 13 0.0003 0.0324 14 0.0003 0.0310 15 0.0003 0.0306 16 0.0003 0.0302 17 0.0003 0.0300 18 0.0003 0.0287 19 0.0003 0.0284 20 0.0003 0.0276 21 0.0003 0.0263 22 0.0003 0.0258 23 0.0003 0.0257 24 0.0003 0.0250 25 0.0003 0.0249 26 0.0003 0.0247 27 0.0003 0.0246 28 0.0003 0.0246 29 0.0003 0.0244 30 0.0003 0.0240 31 0.0003 0.0238 32 0.0003 0.0235 33 0.0003 0.0229 34 0.0003 0.0228 35 0.0003 0.0220 36 0.0003 0.0219 37 0.0003 0.0219 38 0.0003 0.0218 39 0.0003 0.0215 40 0.0003 0.0214 41 0.0003 0.0208 42 0.0003 0.0206 43 0.0003 0.0203 44 0.0003 0.0201 45 0.0003 0.0201 46 0.0003 0.0201 47 0.0003 0.0200 48 0.0003 0.0198 49 0.0003 0.0198 Aberdeen Ave 12.15.16 12/15/2016 3:48:44 PM Page 14 50 51 52 53 54 55 56 57 58 59 60 61 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0002 0.0002 0.0002 Aberdeen Ave 12.15.16 0.0197 0.0196 0.0188 0.0184 0.0181 0.0180 0.0177 0.0171 0.0168 0.0167 0.0164 0.0153 12/15/2016 3:48:44 PM Page 15 Model Default Modifications Total of O changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Aberdeen Ave 12.15.16 12/15/2016 3:49:03 PM Page 20 Appendix Predeveloped Schematic asm 1 1 .37ac Aberdeen Ave 12.15.16 12/15/2016 3:49:03 PM Page 21 Mitigated Schematic ravel rench Bed 1 Aberdeen Ave 12.15.16 12/15/2016 3:49:03 PM Page 22 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright© by: Clear Creek Solutions, Inc. 2005-2013; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1 (866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Aberdeen Ave 12.15.16 1211512016 3:49:03 PM Page 40 Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section V, Page 1 TIR Section V-Conveyance System Analysis and Design TIR Section V Summary: Narrative Per Core Requirement #4, new pipe systems shall be designed with sufficient capacity to convey and contain the 25-year peak flow. Conveyance capacity shall be demonstrated using the methods in Chapter 4 of the KCSWDM. Verification of capacity and performance must be provided for each element of the conveyance system. The analysis must show design velocities and flows for all drainage facilities within the development, as well as those offsite that are affected by the development. The conveyance system will consist of 6" PVC pipes for roof and driveway runoff. The 25-year peak flow for the total runoff from the assumed impervious areas runoff was calculated per WWHM and found to be 0.107 cfs. The conveyance capacity of a 6" PVC pipe with a minimum 1% slope is 0.56 cfs. Therefore, a 6" PVC pipe is sufficient for the design event. See the conveyance capacity calculation on the following page. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 42S.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report Ratimw Methacl -De<eloped Conditions far: Aberdeen A,e Subdirision Mannings Equation: lA~ ·1• 1/" Q=(-)R• S • n n= Ul3 Con,evance r.,.nadl · 4-inch 6-inch 3-inch 10-lnch Slope (hilt) O.INIS 0.13 0.40 0.87 1.55 0.010 0.19 11.56 1.23 2.20 0.015 0.23 0.69 1.50 2.69 o..ozo 0.27 0.79 1.74 3.11 0.025 030 0.89 1.94 3.47 O.ll30 033 0.97 2.13 3.81 0.035 036 1.05 230 4.11 0.040 03S 1.12 2.46 439 0.045 0.40 1.19 2.60 4.66 0.050 0.43 126 2.75 4.91 0.055 0.45 132 2.88 5.15 0.060 0.47 13S 3.01 53& 0.065 0.49 1.43 3.13 5.60 0.070 050 1.49 3.25 5.81 0.075 052 1.54 336 6.02 0.080 054 159 3.47 6.21 0.085 056 1.64 358 6.40 0.090 057 1.68 3.68 659 0.095 059 1.73 3.78 6.77 0.100 0.60 1.78 3.88 6.95 C: E::io Convevance Caoadtv -ENGINeeRING 250 4th Ave. South Suile 200 Edmonds, WA 98020 Aberdeen Ave Subdivision c::; ENGINEERING 12-inch 252 3.57 437 5.05 5.65 6.18 6.68 7.14 757 7.98 S37 8.75 9.10 9.45 9.78 10.10 10.41 10.71 11.01 11.29 By """' ""' ~!lo. VD """ """ N.T.S. .,_,.._ ·16037 .20 December 15, 2016 Section V, Page 2 1211212016 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 J f. 42S.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section VI, Page 1 TIR Section VI -Special Reports and Studies TIR Section VI Summary: Narrative Please refer to the following reports submitted with the application: 1. Geotechnical Engineering Evaluation by Nelson Geotechnical Associates, Inc., dated October 17, 2016. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 December 15, 2016 Technical Information Report Section VII, Page 1 ----------''--------------------------~· TIR Section VII Narrative TIR Section VII -Other Permits Other permits are not anticipated that would contain more restrictive drainage plan requirements. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I f. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section VIII, Page 1 TIR Section VIII -CSWPPP Analysis and Design TIR Section VIII Summary Narrative This section of the TIR is to provide a summary of erosion controls and source controls for the site. The project proposes to subdivide a single 16,161 sf parcel in the R-8 zone into 2 individual single-family lots. The site currently contains one single-family home with a detached garage and a detached accessory building. The existing structures will be demolished in order to add an access and utility tract, and a house on the back lot. The project will add more than 2,000 sf of impervious surfaces and so must meet the Full Drainage requirements from the 2016 King County Surface Water Design Manual as amended by the City of Renton. The project will construct the necessary stormwater improvements for the access/utility tract and lots, but development of Lots 1 and 2 will occur at a later date. ESC and SWPPS measures were chosen per Section D.2 the 2016 King County Surface Water Design Manual. Less than 1 acre of land will be disturbed and therefore the Department of Ecology SWPPP and Construction Stormwater General Permit is not required. ESC Measures The following ESC measures are suggested for each category below: 1. Clearing Limits: To protect adjacent properties, existing trees, and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. The BMPs relevant to marking the clearing limits that will be applied for this project include: • High Visibility Plastic or Metal Fence 2. Cover Measures Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. Temporary cover shall be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). The suggested BMPs for soil stabilization that shall be used on this project include: • Temporary & Permanent Seeding • Mulching • Nets & Blankets • Plastic Covering 3. Perimeter Protection All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged. Silt fences will be installed on ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgenglneering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section VIII, Page 2 the downstream sides of the site. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence 4. Traffic Area Stabilization A stabilized construction entrance will be established to the west side ofthe site using the existing gravel driveway. • Stabilized Construction Entrance 5. Sediment Retention The site is small enough that perimeter protection is expected to be adequate for sediment retention onsite. 6. Surface Water Collection The site is small enough that perimeter protection is expected to be adequate for sediment retention onsite. 7. Dewatering Control Dewatering is not anticipated. 8. Dust Control Dust control will be used to minimize wind transport of soil. Water and/or other dust control measures may be used upon approval by the County. • Dust Control 9. Flow Control Increases in the 2-year and 10-year runoff event is expected to be small due to the size of the site. Flow control measures are not proposed. 10. Protect Existing and Proposed Flow Control BMPs Stormwater facilities and on-site BMPs areas are identified on the Temporary Erosion Control Plan. These areas shall be protected from sedimentation and soil compaction that would adversely affect infiltration. 11. Maintain BMPs BMPs will be maintained and repaired as necessary throughout construction. The CSWPP supervisor shall review the site for ESC and SWPPS at least weekly and within 24 hours of significant storms. All temporary erosion and sediment control BMPs will be removed within 30 days after achieving final site stabilization. 12. Manage the Project Projects shall assign a qualified CSWPPP supervisor to be the primary contact for ESC and SWPPP issues and reporting. E5 ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www .cge ngi nee ring.com Aberdeen Ave Subdivision 16037.20 Technical Information Report SWPPS Measures The following SWPPS measures are expected for the site. 1. Concrete Handling December 15, 2016 Section VIII, Page 3 Management practices per Section D.2.2.1 "Concrete Handling" shall be utilized any time concrete is used to minimize and eliminate concrete, concrete process water, and concrete slurry runoff. 2. Concrete Washout Area Prevent or reduce the discharge of pollutants to stormwater from concrete waste by conducting washout off-site, or performing on-site washout in a designated area to prevent pollutants from entering surface waters or ground water. 3. Sawcutting and Surfacing Pollution Prevention Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include, but are not limited to, sawing, coring, grinding, roughening, hydrodemolition, bridge and road surfacing. 4. Material Delivery, Storage and Containment These procedures are suitable for use at all construction sites with delivery and storage of the following materials: Petroleum products such as fuel, oil and grease; Soil stabilizers and binders (e.g. Polyacrylamide); Fertilizers, pesticides and herbicides; Detergents; Asphalt and concrete compounds; Hazardous chemicals such as acids, lime, adhesives, paints, solvents and curing compounds; Any other material that may be detrimental if released to the environment. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I t. 425.778.5536 www.cgengineering.com Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section IX, Page 1 TIR Section IX -Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section IX Summary: Narrative A Declaration of Covenant is provided for the proposed flow control BMP. There are no flow control facilities. ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.ssoo I f. 425.778.5536 www.cgengineering.com RECORDING REQUESTED BY AND WIIEN RECORDED MAIL TO: CITY CLERK'S OFFICE CITY OF RENTON 1055 SOUTH GRADY WAY RENTON WA 98057 DECLARATION OF COVENANT FOR MAINTENANCE AND INSPECTION OF FLOW CONTROL BMPS Grantor: ____________ _ Grantee: City of Renton L ID . 1. THAT PORTION OF TRACT 244 INC D HILLMAN'S LAKE ega escnp ton: _________________________ ~ WASHINGTON GARDEN OF EDEN ADDITION TO SEATTLE DIVISION NO 4, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 11 OF PLATS, . . LAST PAGE Add1t10nal Legal(s) on: _______________________ _ 334390-1606 Assessor's Tax Parcel ID#: ______________________ _ IN CONSIDERATION of the approved City of Renton(check one of the following) D residential building permit, D commercial building permit, D clearing and grading permit, D subdivision pennit, or ~ short subdivision permit for Application File No. LUA/SWP ________ relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants(covenant) with City or Renton, a political subdivision of the state of Washington, that he/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs I through 8 below with regard to the Property. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agree) as follows: 1. Grantor(s) or his/her(their) successors in interest and assigns ("Owners") shall retain, uphold, and protect the stormwater management devices, features, pathways, limits, and restrictions, known as flow control best management practices ("BMPs"), shown on the approved Flow Control BMP Site Plan for the Property attached hereto and incorporated herein as Exhibit A. 2. The Owners shall at their own cost, operate, maintain, and keep in good repair, the Property's BMPs as described in the approved Design and Maintenance Details for each BMP attached hereto and incorporated herein as Exhibit B. 3. City or Renton shall provide at least 30 days written notice to the Owners that entry on the Property is planned for the inspection of the BMPs. After the 30 days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting the BMPs. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the BMPs and provide a written report describing their condition, If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen days of receiving the City's notice of inspection. Within 30 days of giving this notice, the Owners, or the engineer on behalf of the Owners, shall provide the engineer's report to the City of Renton. lf the report is not provided in a timely manner as specified above, the City of Renton may inspect the BMPs without further notice, 4. If the City determines from its inspection, or from an engineer's report provided in accordance with Paragraph 3, that maintenance, repair, restoration, and/or mitigation work is required for the BMPs, The City shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work) required under RMC 4-6-030. The City shall also set a reasonable deadline for completing the Work or providing an engineer's report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access to re-inspect the 13MPs unless an engineer's report has been provided verifying completion of the Work. Jfthe work is not completed properly within the time frame set by the City, the City may initiate an enforcement action. failure to properly maintain the BMPs is a violation of RMC 4-6-030 and may subject the Owners to enforcement under the RMC 1-3, including fines and penalties. 5. Apart from performing routine landscape maintenance, the Owners are hereby required to obtain written approval from the City or Renton before performing any alterations or modifications to the BMPs. 6. Any notice or approval required to be given by one pmty to the other under the provisions of this Declaration of Covenant shall be effective upon personal delivery to the other party, or after three (3) days from the date that the notice or approval is mailed with delivery confirmation to the current address on record with each Party. The parties shall notify each other of any change to their addresses. 7. This Declaration of Covenant is intended to promote the efficient and effective management of surface water drainage on the Property, and it shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest and assigns. 8. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City of Renton that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Maintenance and Inspection of rlow Control BMPs is executed this __ day of _________ , 20 GRANTOR, owner of the Property GRANTOR, owner of the Property ST A TE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: ____________________ ,tome known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this __ day of _________ , 20 __ Printed name Notary Public in and for the State of Washington, residing at My appointment expires __________ _ • FULL LEGAL DESCRIPTION: THAT PORTION OF TRACT 244 INC D HILLMAN'S LAKE WASHINGTON GARDEN OF EDEN ADDITION TO SEATILE DIVISION NO 4, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 11 OF PLATS, PAGE 82, IN KING COUNTY, WASHINGTON, DESCRIBED AS FOLLOWS BEGINNING AT A POINT ON THE WEST BOUNDARY LINE OF SAID TRACT, 301 FEET SOUTH OF THE NORTHWEST CORN ER OF SAID TRACT; TH ENCE SOUTH 64 FEET; THENCE EAST 252.3 FEET, MORE OR LESS, TO THE EAST BOUNDARY LINE OF SAID TRACT; THENCE NORTH, ALONG SAID EAST BOUNDARY LINE, 64 FEET; THENCE WEST 252.3 FEET, MORE OR LESS, TO POINT OF BEGINNING; (BEING THE NORTH 365 FEET OF SAID TRACT 244, EXCEPT THE NORTH 301 FEET THEREOF). I .;. l , '·\./ ! ; I cl ,z'- i~ :ij'z aw -w ~,& •jw 8 "' " « ',-1· I ' lg ,:::; • Exhibit A: Flow Control BMP Site Plan 1,/· ~---, !-:.-:-::_-_.,...._-:-~~--._._-:; ~;:: ':------------~~=~,-=-~ ;~=---.,: °'.:·~ ~--c _::; ~ _---=-_:: ~ -_:: =--=-~ ---C 1 : I I , ; lii I I \ '. I I I I I = :I I I i I r- 1 I I :: I I ""--' I ,,12, .·: ' . I 'I I I I 'i' ·J;j I I i'· I i I 1! ; :i, I I ~ ', :i I [: I I 1~ . iii I j_',_.J __________________ ; 1 f : } / ~I ~-~1 ' I 'i ·-.. -.-·;;;:z;q,_L_~~ ~;-;l":~;~'c"~"~ --{~ ~=--c-=-~::--=-~-(_j 80' x 5' x 2 Deep gravel infiltration trench MAINTENANCE INSTRUCTIONS FOR FULL INFILTRATION Your property contains an on-site BMP (best management practice) called "full infiltration," which was installed to mitigate the storm water quantity and quality impacts of some or all of the impervious surfaces on your property. Full infiltration is a method of soaking runoff from impervious area (such as paved areas and roofs) into the ground. If properly installed and maintained per Appendix A of the City ofRenton's Surface Water Design Manual, full infiltration can manage runoff so that a majority of precipitation events are absorbed. Infiltration devices, such as gravel filled trenches, drywells, and ground surface depressions, facilitate this process by putting runoff in direct contact with the soil and holding the runoff long enough to soak most of it into the ground. To be successful, the soil condition around the infiltration device must be reliably able to soak water into the ground for a reasonable number of years. Infiltration Devices The infiltration devices used on your property include the following as indicated on the site plan (CHECK Tl IE BOX(ES) THAT APPLY): l&lgravel filled trenches, Ddrywells, Dground surface depressions. MAINTENANCE RESTRICTIONS The size, placement, and composition of these devices as depicted by the site plan and design details must be maintained and may not be changed without written approval from the City of Renton or through a future development permit from the City of Renton. INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES • Jnfiltration devices must be inspected annually and after major storm events to identify and repair any physical defects. • Maintenance and operation of the system should focus on ensuring the system's viability by preventing sediment-laden flows from entering the device. Excessive sedimentation will result in a plugged or non-functioning facility. • If the infiltration device has a catch basin, sediment accumulation must be removed on a yearly basis or more frequently if necessary. • Prolonged ponding around or atop a device may indicate a plugged facility. If the device becomes plugged, it must be replaced. • Keeping the areas that drain to infiltration devices well swept and clean will enhance the longevity of these devices. • For roofs, frequent cleaning of gutters will reduce sediment loads to these devices. ~1'~. tlCUSE I,, , ROOFD0\o\'f.5"0LIT OVERFLOW SPL'.S•I BLOCK TYPICAL FULL INFILTRATION APPLICATIONS .r:~&.~~~EOR6" ,-\CB SUMPw/SOLID LID _ f / PERFORATED 11 I "" ~-,~ , =====., ;r=-, <::::::::::--Y INFILTRATION TRENCH ~LAN VIEW NTS ROOF DRAIN TRENCH SETBACK FROM BUILDING AS REQUIRED 15' MIN ROOF DRAIN SECTION VIEW NTS TABLE. SEE SECTION C.22 2 "ARK CF~TER CF HOLE V~TH l"CAl'FEQP,/C OR OTHER MEANS FLUSH WITH.SUHCACC _l I , MIN FINE MESH SCREEN OVERFLOW SPLASH BLOCK 11 ] r, _j_l II'~-I 1'MIN ~1'ilN. j -I SETBACK -----j FROM llUILOING 5'MIN CB SUMP w/SOLID LIO COMPACTED BACKFILL FILTER FABRIC 4· RIGID OR 6" FLEXIE!LE PERFORATED PIPE tl"-i" WASHED ROCK SECTION A NT--g-- '.(~))">;;>;:'%:~~'); 314"T01-1/2"~ WASHED DRAIN ':':/_'9 ROCK ':'.--~ --~ FROM ROOF GRASS 1S'" MIN _ __t 15' MIN. AS \, t ee= i\ ~ ... i~ ~~~: --' ~ ~;it HNE, ME&H SC SEEN CATC~ BASIN S1DE5 OF HCLE CYARDnRA"l m~~~£fA~~~6 IS MIN _AS REOUlnE~ SE~SECTION C;: Z 3 , , I .j,_ ~' "C, ~ ' -' " 4a INCi! OIAl,IE:HR VARIE:S 'HOLEFlLLfr.....,-H 1 1," 3 WASHED DRAIN ROCK MIN. 1' AflOVLSVISONAL HIGH GROUNtlWATER T/Ull.E SE£SECTIONC112 ~:i~~~~~~GH i GROUNDWATER TABLE, SEE SECTION C 2.2 2_l__ ~1----;:;~l-~-~DJ X_"_S_Ei9JION NTS ; ·-_J_ MIN 1" ABOVE I ' SEASONAL HIGH I 2· MIN i ;:~L~~~~:TER ~---i SECTION C.2.2.2 X-SECTION NTS NOTE: SEEC223FOR TRENCH LENGTHS, TRENCH SPACING AND SITE LIMITATIONS -Aberdeen Ave Subdivision 16037.20 Technical Information Report December 15, 2016 Section X, Page 1 TIR Section X -Operation and Maintenance Manual TIR Section X Summary: Narrative Maintenance instructions for the proposed flow control BMP is included in the Declaration of Covenant found in Section IX with a proposed Flow Control BMP site plan. Please note that the site plan is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as-built drawings are completed for the site. The project contractor will be responsible for passing along the information in this maintenance manual to the owner. Upon request by the City, it shall be made available for their inspection. Facilities shall be inspected for defects. The frequency of this should occur annually. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. C5 ENGINEERING 250 4th Avenue S0uth1 Suite 200 Edmonds, WA 98020 ph. 425.778.8500 I 1. 425.778.5536 www.cgengineering.com