HomeMy WebLinkAboutC21006052_TIR_Drainage Report_Approved1
TECHNICAL INFORMATION REPORT
FOR
Tran-Nguyen
Development
2309 Aberdeen Avenue NE
Renton, Washington
December, 2022
12-26-2022
DEVELOPMENT ENGINEERING
yqi 04/21/2023
SURFACE WATER UTILITY
JFarah 04/21/2023
2
TABLE OF CONTENTS
1.0 Project Overview………………………………………………………..…….…...4 1.1 General……………………………………………………………………………4 1.2 Pre-Developed Condition……………………………………………………...…4 1.3 Proposed Development…………………………………………………………...4 1.4 Proposed Storm Drainage Facilities………………………………………………5
1.5 Soils………………………………………………………………………………5 2.0 Conditions and Requirements Summary…………………………………..…….7 2.1 Conditions and Requirements…………………………………………………….7 2.1.1 Core Requirements……………………………………………………………7 2.1.2 Special Requirements…………………………………………………………8 3.0 Offsite Analysis…………………………………………………………………....10 3.1 Standard Requirements…………………………………………………..…..….10 3.2 Scope of Analysis…………………………………………………………….....10 3.2.1 Resource Review……………………………………………………………10 3.2.2 Field Inspection…………………………………………………………..…10
3.2.3 Drainage System Description and Problem Descriptions………………..…10 3.2.4 Mitigation of Existing or Potential Problems………………………………10 4.0 Flow Control and Water Quality Facility Analysis and Design………..………11 4.1 Existing Site Hydrology…………………………………………………………11 4.2 Proposed Site Hydrology………………………………………………………..11
4.3 Performance Standards………………………………………………………….11 4.4 Flow Control Facilities………………………………………………………….12 4.5 Water Quality Facilities…………………………………………………………12 5.0 Conveyance System Analysis and Design……………………………….……….13 5.1 Standards Requirements…………………………………………………………13
5.2 Proposed Conveyance System…………………………………………….….…13 6.0 Special Reports and Studies……………………………………………………...14 6.1 Geotechnical…………………………………………………………………….14 7.0 Other Permits……………………..……………………………………………….15 7.1 NPDES Permit…………………………………………………………………..15 8.0 CSWPPP Analysis and Design…………………………………………….……..16 8.1 ESC Plan………………………………………………………………………...16 9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant……………………………………………………….…17 9.1 Bond Quantities Plan………………………………………………………........17
9.2 Declaration of Covenant for Privately Maintained Flow Control BMPs……….17 10.0 Operations and Maintenance Manual…………………………………...……...18 10.1 Maintenance Recommendations……………………………………………….18
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LIST OF FIGURES
Figure 1 – Vicinity Map
Figure 2 – Existing Conditions (Existing Drainage) Figure 3 – Developed Conditions (Proposed Drainage) Figure 4 – Flow Chart for Determining the Type of Drainage Review Required
Figure 5 – Flow Control Application Map
Figure 6 – Groundwater Protection Areas Figure 7 – Downstream Analysis Map Figure 8 – Bond Quantities Worksheet Figure 9 – Maintenance and Operations Manual
Figure 10 – TIR Worksheet
LIST OF TABLES
Table 1 – Pre-Developed Conditions Surface Areas
Table 2 – Developed Conditions Surface Areas
LIST OF APPENDICES
APPENDIX A – Geotechnical Report
APPENDIX B – Drainage, Cross-sections and Detail Plans APPENDIX C – BMPs Design Criteria and Maintenance Standards APPENDIX D – Declaration of Covenant for Maintenance and Inspection of On-Site BMPs
Appendix E – Continuous Model Calculations Output
Appendix F – Stormwater Pollution Prevention Plan Appendix G – Drainage Basin Surface Areas Geotechnical Report
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1.0 PROJECT OVERVIEW
1.1 General
The Nguyen single-family homes Project proposes to construct three new single-
family residences located at 2309 Aberdeen Avenue NE, in Renton, WA (See
Figure 1 – Vicinity Map). The development will include the construction of three, two story, single-family residences, pathways, landscaping, On-site BMPs and associated right of way improvements along the Project frontage.
1.2 Pre-developed Condition
The general location of the project site is shown on Figure 1 (Vicinity Map). The site consists of a roughly square-shaped covering approximately 0.84 acres. The site is currently vacant but was previously occupied by a single-family residence
within the western portion of the site. Topography within the western and central
portion of the site is kinda hilly from west of east of the site with moderately landslide. The eastern portion of the property is generally level. The site is generally vegetated by grass-covered yard areas, young to mature trees, and landscaping. A horseshoe-shaped gravel driveway is located within the eastern
portion of the property. The property is bound to the north, south, and west by
single-family residences, and to the east by Aberdeen Avenue NE. See Figure 2 for existing site conditions. See Table #1 below for Pre-Developed Condition Surface Areas.
Table 1 – Pre-Developed Condition Surface Areas
Type of Land Covers Area (ac)
Ex. PGIS 0.0775
Ex. NPGIS 0.0420
Ex. Pervious 0.7205
Total Lot Area 0.8400
1.3 Proposed Developed Condition
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The development proposes to construct three new single-family residences located at 2309 Aberdeen Avenue NE, in Renton, WA (See Figure 1 – Vicinity
Map). The development will include the construction of three, two story, single-
family residences, pathways, landscaping, On-site BMPs and associated right of way improvements along the Project frontage. See Table #2 below for proposed developed conditions surface areas and Figure 3 for developed site conditions.
Table 2 – Developed Condition Surface Areas
Type of Land Covers Area (ac)
Dev. PGIS 0.1045
Dev. NPGIS 0.2755
Dev. Pervious 0.4600
Total Area 0.840
1.4 Proposed Storm Drainage Facilities
The roof surface runoff for each of the residence will be tightline and convey to
an infiltration trench on each lot. The access roadway and residences driveway will be conveyed to the proposed storm filter for water quality treatment then pipe to an infiltration trench for flow control for the runoff. See Figure 3 for the proposed BMPs location, cross-sections, and details.
1.5 Soils
The geologic units for this site are shown on Preliminary Geologic Map of Seattle and Vicinity, Washington, by Waldron, H.H., Mulineaux, D.R., and Crandell, D.r., (USGS, 1961). This site is mapped as younger gravel (Qyg) with younger
sand (Qys) and alluvium (Qa) mapped nearby. The younger gravel and sanddeposits are described as fine to coarse sand that contains varying amounts ofgravel. The alluvium is described as silt with varying amounts of sand andorganic material. Our explorations generally encountered fine to coarse sand withvarying amounts of sand and organic material. The explorations generally
encountered fine to coarse sand with varying amounts of gravel and silt within thewestern and central portion of the property that we interpreted as youngeroutwash soils. The explorations within the very eastern portion of the propertygenerally encountered silt with sand and silty fine to medium sand that weinterpreted as native alluvium and younger sand deposits at depth. See
Geotechnical Report in Appendix A for more detail of soil information.
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2.0 CONDITIONS AND REQUIREMENTS SUMMARY
2.1 Conditions and Requirements
Stormwater management for this project will be provided in accordance with the 2017 City of Renton Surface Water Design Manual requirements. The flow chart in Figure 5 – Flow Chart for Determining the Type of Drainage Review Required, provides the framework to determine which core Requirements apply to the
Project. The Project will add/replace more than 5,000 square feet of impervious surface; therefore, directed drainage review is required. The Project must comply with Core Requirements #1 - #9 and Special Requirements #1 - #6 per 2017 Renton SWDM.
2.1.1 Core Requirements
Core Requirement #1: Discharge at Natural Location
•Stormwater plans have been prepared; a copy is in Appendix B. 2017 City
of Renton Surface Water Design Manual requirements for flow controland water quality treatment through the use of infiltration trenches. Anyrunoff not detain by the infiltration trenches will be disperse and infiltrateinto ground by yard grass like “natural discharge location”.
Core Requirement #2: Offsite Analysis
•All projects are required to perform an offsite analysis. A Level 1 analysishas been performed and presented in Section 3.0 of this report.
Core Requirement #3: Flow Control
•The project falls within the duration flow control standard (ForestedConditions) based on the City of Renton Flow Control Application Map,See Figure 5. A continuous Model will be used to calculate the
infiltration trenches sizes to handle the added flow for the project. Flow
Control will be mitigated by matching the predeveloped durations for therange of predeveloped discharge rates from 50% of the 2-year peak flowup to the full 50-year peak.
Core Requirement #4: Conveyance System
•Runoff from the residence roofs will sheet flows to the downspout andpiped to each individual infiltration trench. Runoff from residencedriveways and access roadway flows to the storm filter and then to an
infiltration trench. See figure 3 for infiltration trenches and catch basin
filter locations.
Core Requirement #5: Erosion and Sediment Control
•Erosion and Sediment Control (ESC) Plans has been prepared and will be
submitted with the Stormwater plans. Additionally, the Contractor will be
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required to prepare a Stormwater Pollution Prevention and Spill (WSPPS) Plan to comply with County requirements. Applicable Best Management
Practices (BMPs) will be selected and maintained by the Project Owner to
control pollution.
Core Requirement #6: Maintenance and Operations
•A maintenance and operations manual had been prepared and is provided
in Section 10.0 of this report.
Core Requirement #7: Financial Guarantees and Liability
•All required bonds will be paid by the Owner prior to permit approval, per
City of Renton/ King County Manual. See Section 9.0 of this report forBond Quantities.
Core Requirement #8: Water Quality
•Runoff Treatment is not required for this project pollution generatingimpervious surfaces (PGIS). PGIS is less than 5,000 SF threshold. Butthis project will proposed to provide a stormfilter catch basin to providewater quality treatment for access roadway and driveways.
Core Requirement #9: On-Site BMPs
•This project required to implements On-Site BMPs per 2017 City ofRenton SWDM requirements for lot larger then 22,000 sf. According tothe Geotechnical Report, infiltration is feasible for this parcel. Each of the
proposed roof runoff will be convey to each individual infiltration trench
to mitigate for the roof impervious surface. Residence driveways androadway access will be mitigated by implemented catch basin filter then toan infiltration trench. This project proposed to use full infiltration tomitigate for the new added, replaced impervious surfaces. A continuous
model was used to analyze the infiltration trenches to mitigate for each
roofs, and the residence driveways/ access roadway. Flow Control will bemitigated by matching the predeveloped durations for the range ofpredeveloped discharge rates from 50% of the 2-year peak flow up to thefull 50-year peak. See Appendix E for model results and met all LID
performance standards.
2.1.2 Special Requirements
Special Requirement #1: Other Adopted Requirements
•No other area-specific requirements apply to this Project.
Special Requirement #2: Flood Hazard Delineation
•Not applicable. The Project is not adjacent to a flood hazard area.
Special Requirement #3: Flood Protection Facilities
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•Not applicable. There are no flood protection facilities on or adjacent to
the site.
Special Requirement #4: Source Control
•Not applicable. The Project does not require a commercial building orcommercial site development permit.
Special Requirement #5: Oil Control
•Not Applicable. This site is not classified as high-use roadway.
Special Requirement #6
•Aquifer Protection Area.This project falls within Zone 2 of the APA. This project will complywith requirement to protect the aquifer protection area by implement liner
wherever it is required to protect the aquifer. This project will useGeomembrance Liners described in Section 6.2.4.1 from the 2017 City ofRenton Surface Water Design Manual in all the infiltration trenches toprotect the Zone 2 of the APA.
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3.0 OFF-SITE ANALYSIS 3.1 Standard Requirements Offsite analysis is required for all projects per 2017 City of Renton SWDM. This Project is not exempt from this requirement, since the project will add more than 2,000 square feet of impervious area. 3.2 Scope of Analysis As shown in Figure 7, the offsite analysis study area extends approximately ¼ mile downstream from the Project site. 3.2.1 Resource Review
• City of Renton COR Map.
3.2.2 Field Inspections The study area was observed on March 9, 2021. Atmospheric conditions were chill and semi sunny. No evidence of downstream conveyance issues was identified. All of downstream conveyance is storm sewer pipe system
underground. From the proposed development to May Creek is all underground
drainage pipe system. From May Creek to Lake Washington open Creek channel flow to Lake Washington. 3.2.3 Drainage System Description and Problem Descriptions
Figure 7 shows a map of the downstream system. No downstream drainage issues were identified by the Level 1 downstream analysis. 3.2.4 Mitigation of Existing or Potential Problems
Since no downstream issues were identified no further downstream analysis will be required. No mitigation measures, in addition to the On-site BMP’s are proposed.
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4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Existing Site Hydrology
The general location of the project site is shown on Figure 1 – Vicinity Map. The site consists of a roughly square-shaped covering approximately 0.84 acres. The site is currently vacant but was previously occupied by a single-family residence withing the western portion of the site. Topography within the western and
central portion of the slopes gently down from the western property line to the
eastern portion of the property. The eastern portion of the property is generally level. The site is generally vegetated by grass-covered yard areas, young to mature trees, and landscaping. A horseshoe-shaped gravel driveway is located within the eastern portion of the property. The site does not have any stormwater
management. Stormwater runoff either infiltrate into the ground and/or sheet
flows toward Aberdeen Avenue NE. See Figure 2 for an existing site conditions and photos. 4.2 Proposed Site Hydrology
All of the residence roofs surface runoff sheet flow to downspouts. The downspout will be tightlined to each individual infiltration trench for each lot. Other impervious surfaces onsite, including residence driveways and access roadway has been graded to flows to a catch basin filter then the an infiltration
trench. See Figure 3 for developed condition flow patterns.
4.3 Performance Standards The project falls within the duration flow control standard (Forested Conditions)
based on COR Flow Control Application Map, See Figure 5. This project will use
the continuous model MGSFlood application to size the infiltration trenches to meet the minimum required performance for flow control duration standard matching forested site conditions is; Developed discharge durations shall not exceed per developed durations for the range of pre-developed discharge rates
form 50% of the 2-year peak flow up to the full 50-year peak flow.
4.4 Flow Control Facilities
This project proposed four infiltration trenches, one in each lot to mitigate for the
new roof surfaces. Each roof surface area equal to 4,000 sf. The fourth infiltration trench is proposed for the drivewways and the access roadway. Using the continuous Model MGSFlood Program to size the infiltration trench to meet pre-developed discharge rates form 50% of the 2-year peak flow up to the full 50-
year peak flow. From the output, the required infiltration trench to mitigate for
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the 4,000 sf of roof surface area is 20 ft x 10 ft x 2 ft. Residence driveways and roadway access impervious surfaces total is approximately 4,600 sf of impervious
surface area. This project proposed a 110 ft x 2 ft x 2 ft to mitigate for added
impervious area for the residence driveway and access roadway. See Appendix E for Program Output and See Appendix C for On-site BMPs for design criteria and Appendix B for BMPs location, cross sections and details.
4.5 Water Quality Facilities
This project contains PGIS within the residence driveways and access roadway to the houses. The Project new plus replace PGIS is less 5,000 SF. Therefore, basic treatment for this project is not required. But this project is proposing a catch basin storm filter for the new plus replaced PGIS for treatment before piped to the
infiltration trench for flow control. See Appendix C for details.
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5.0 CONVEYANCE SYSTEMS ANALYSIS AND DESIGN 5.1 Standard Requirements New pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25 years peak flow.” All proposed conveyance systems will meet or exceed this requirement.
Rational Method:
Q = CIA/Kc
I = m/(Tc)^n
25 year storm
m=6.89 n=0.539
I = 6.89/(5 min.)^0.539
I = 2.98 in/hour
Q = CIA/Kc
C = 0.99, I = 2.98, A = 0.092, Kc = 1
Q = 0.99(2.98)(0.092)/1
Q = 0.271 cfs
D = 1.33(nQ/ s )^3/8 ; Where n = 0.013, s = 2%, Q = 0.271 cfs
D = 1.33 (0.013*0.271)/ .02 ^3/8
D = 0.333 ft
D = 3.99 inches diameter pipe to convey the 25 yrs storm.
This project proposed 6 inches diameter pipe for all conveyance pipes.
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5.2 Proposed Conveyance System
Roof surface runoff from the three residences will be collected in downspout tightlines and piped to infiltration trench for each lot. In general, runoff from non-building areas will either infiltrate into the ground through lawn area. Residence driveways and access roadway sheet flows to side
of the roadway and gutter flow to catch basin filter then to infiltration trench.
The project will utilize a 6-inch dia. PVC at 2.0% slope to tightline the residence roofs runoff to an infiltration trench. See Appendix B for drainage plans.
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6.0 SPECIAL REPORTS AND STUDIES 6.1 Geotechnical A copy of the report titled, “Geotechnical Investigation,” dated February 26, 2021 by Nelson Geotechnical Associates, Inc. is provided in Appendix A.
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7.0 OTHER PERMITS 7.1 NPDES Permit A Construction Stormwater General Permit is not required since the Project will be disturbing less than one acre with construction activities such as clearing,
grading, or excavation.
16
8.0 CSWPPP ANALYSIS AND DESIGN 8.1 ESC Plan A preliminary ESC plan has been provided in Appendix B. A final ESC plan will be prepared by the Contractor according to The Contractor’s means and methods
and construction sequencing. The ESC plan will be prepared in accordance with the City’s requirements. Erosion control measures indicated on the preliminary plan includes: marking clearing limits and the use of straw wattles. Sediment control measures indicated on the preliminary plan include a stabilized construction entrance and catch basin/inlet insert protection.
SWPPS Plan A SWPPS plan will be prepared by the Contractor according to the Contractor’s means and methods. The SWPPS plan will be prepared in accordance with
City’s requirements.
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9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT
9.1 Bond Quantities Plan
A Bond Quantities Worksheet is provided in Figure 10.
9.2 Declaration of Covenant for Privately Maintained Flow Control BMPs
A copy of the unsigned Declaration of Covenant is provided in Appendix D. A furnished copy of the Declaration of Covenant will be provided by the Owner at a later time for the infiltration trenches and catch basin storm filter.
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10.0 MAINTENANCE AND OPERATIONS MANUAL 10.1 Maintenance Recommendations Operation and maintenance requirements for the proposed drainage elements and On-site BMPs have been provided for reference in Figure 9.
19
Figure 1
Site Location
18
Figure 2
Existing Conditions (Existing Drainage)
19
Figure 3
Developed Conditions (Proposed Drainage)
S-421002
DATE:
FIELDBOOK:
DRAWING NO:
PAGE:
SHEET: OF:
SCALE:
DESIGNED:
DRAWN:
CHECKED:
APPROVED:NO.REVISION BY DATE APPR
FILENAME:SURVEYED:
VERTICAL: NAVD 1988
IF NOT ONE INCH
ONE INCH
AT FULL SCALE
HORIZONTAL: NAD 1983/1991
SCALE ACCORDINGLY
DATUM
Planning/Building/Public Works Dept.
CITY OF
RENTON
IN COMPLIANCE WITH CITY OF RENTON STANDARDSELE.=268.13BOTTOM OF DITCHNTS
SCALE IN FEET
02010 20 40
LEGEND
PROPOSED STROM DRAIN LINE
EXISTING PROPERTY BOUNDARY LINE
EXISTING CONTOUR LINE
EXISTING EDGE PAVEMENT
C-8.0
288
1
2
3
4
5
14
4
4
4
2
3
REMOVED EXISTING CB
REMOVED EXISTING CB
IE (E)=263.10
IE (S)=265.08
IE (N)=263.30
RIM=270.15
CB TYPE 2
74'ELE.=268.5BOTTOM OF DITCH6
BOTTOM INFILTRATION TRENCH ELEVATION
6
5
5
5
EXST. IE( N)= 262.79'
EXST. IE (S)= 263.12'
IE (W) = 263.10
EXST. IE (SE) = 265.24'
RIM = 271.34'
EXISTING SDMH
IE (S)=264.50
IE (N)=264.60
RIM=269.70
CB TYPE 2
BUILDING PERMIT
FUTURE
BOT ELE.=273.
TOP ELE.=275
FOR FOOTING DRAIN
2'X4' INFILTRATION TRENCH (FUTURE)
R-421007
SEE COR.STD. 226.00
CLEAN OUT
6/16/2022
BUILDING PERMIT
FUTURE
RIM=270.31
THE TOP OF SIDEWALK
ADJUST EXISTING MH TO FLUSH WITH
DRAINAGE & SEWER PLAN
TRAN-NGUYEN DEVELOPMENT
NOTES
SIDEWALKPLANTERBUILDING PERMIT
FUTURE
6" STORM WATER PIPE MIN. 2.0% (ASTM D-3034 PVC)
ROOF DRAIN MIN 2% GRADE (ASTM D-3034 PVC)
AND FILL WITH SAND
PLUG THE EXISTING DRAINAGE PIPE
12" STORM DRAIN, L=54.0', S=3.0% (ASTM D-3034 PVC)
12" STORM DRAIN, L=60.0', S=2.0% (ASTM D-3034 PVC)
12" STORM DRAIN, L=81.0', S=2.0% (ASTM D-3034 PVC)
LINER WILL BE REQUIRED TO PROTECT AQUIFER
DURING EACH BUILDING CONSTRUCTION
INDIVIDUAL 10' X20' INFILTRATION TRENCH WILL BUILD
IE (N)=266.70
RIM=270.88
EXISTING CB
SEE COR.STD. 406.1
IE=268.20
RIM=272.20
SSCO # 3
SEE COR.STD. 406.1
IE=270.90
RIM=275.50
SSCO # 2
12/26/2022
SEE COR.STD. 406.1
IE=272.80
RIM=275.50
SSCO # 1
10' UTILITY EASEMENT
CONTRACTOR SHALL FIELD VERIFY IE
CONNECT WITH EXISTING 8 " SEWER LINE
CONTRACTOR SHALL FIELD VERIFY IE
CONNECT WITH EXISTING 8 " SEWER LINE
SEE C-22.0 FOR DETAILS
IE=269.50
RIM=271.8
CONTECH STORM FILTER
SEE C-23.0 FOR DETAILS
BOT ELE.=268.50
TOP ELE.=271.0
3' X 74' INFILTRATION TRENCH
0.5%
IE ( S) = 266.24
IE ( N) = 269.80'
IE (W) = 269.82'
RIM = 273.45'
CB TYPE 2
EXISTING CB REPLACE WITHWWP-27-4210TED-40-4210272
274276 147.8190'80'
20'
50'
DF30DF22DF32
DF36
DF30
DS18DF30DF24DF26DF34DF28DF32
278 274290288
280
29082.6'147.81N0°30'04"ES89°10'27"W252.60'N0°29'37"E252.62'N89°08'52"E
282
284
286
272
278 276 274
0+00
1+00
1+701+70
ABERDEEN AVE NE 10'147.815'5'
BSBL 20' BSBL20' BSBL20' BSBL
29' BSBL42' BSBL32' BSBL23' BSBL
BSBL
BSBL
24' BSBL
0+001+001+791+79
272
272
288
284 282
EXISTING
GRAVEL DRIVEWAY
274
276
286 284
282
278 276
274 272
280
20
Figure 4
Flow Chart for Determining the Type of Drainage Review
Required
SECTION 1.1 DRAINAGE REVIEW
12/12/2016 2017 City of Renton Surface Water Design Manual
1-14
FIGURE 1.1.2.A FLOW CHART FOR DETERMINING TYPE OF DRAINAGE REVIEW REQUIRED
21
Figure 5
Flow Control /Water Quality
Application Map
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,§-405
,§-405
µ0 1 2Miles
Flow Control Application Map
Reference 15-A
Date: 01/09/2014
Flow Control Standards
Peak Rate Flow Control Standard (Existing Site Conditions)
Flow Control Duration Standard (Existing Site Conditions)
Flow Control Duration Standard (Forested Conditions)
Flood Problem Flow
Unincorporated King County Flow Control Standards
Renton City Limits
Potential Annexation Area
project site
highlight and point
the project location
22
Figure 6
Groundwater Protection Area/
Environmental Sensitive Areas
23
Figure 7
Downstream Analysis Map
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Figure 8
Bond Quantities worksheet
1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430‐7200Date Prepared: Name:PE Registration No:Firm Name:Firm Address:Phone No.Email Address:Project Name: Project Owner:CED Plan # (LUA):Phone:CED Permit # (C):Address: Site Address:Street Intersection:Addt'l Project Owner:Parcel #(s):Phone:Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:NOWater Service Provided by:If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: AddressAbbreviated Legal Description:THE SOUTH ONE‐HALF OF THE NORTH ONE‐HALF OF TRACT 253, C.D. HILLMAM'S LAKE WASHINGTON GARDEN OF EDEN DIVISION NO.4, ACCORDING TO THE PLAN THEREOF RECORDED IN VOLUME 11 OF PLATS, PAGE 82, RECORDS OF KING COUNTY, City, State, Zip2309 Aberdeen Ave NE, Renton, WA 980562309 Aberdeen ave NEAdditional Project OwnerNE 24th St########21‐000206206‐384‐369012/28/2022Prepared by:FOR APPROVALProject Phase 1wu868good@outlook.comSTEVE WU38852Tendem engineering consultants inc8822 NE 178th St Bothell, WA 98011206‐795‐5674SITE IMPROVEMENT BOND QUANTITY WORKSHEETPROJECT INFORMATIONCITY OF RENTONCITY OF RENTONPhoneEngineer Stamp Required (all cost estimates must have original wet stamp and signature)Clearing and GradingUtility ProvidersN/AProject Location and DescriptionProject Owner InformationTran‐Nguyen DevelopmentRenton, WA 980563343901963Long & Thu Thuy Ngyuyen & Vu TranPage 1 of 2Ref 8‐H Bond Quantity WorksheetSECTION I PROJECT INFORMATIONUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/202212/28/2022
10.1%Total Estimated Construction CostsEA + B + C + D$ 236,287.86Estimated Civil Construction Permit ‐ Construction Costs2Stormwater (Drainage)C$ 27,872.13As outlined in City Ordinance No. 4345, 50% of the plan review and inspection fees are to be paid at Permit Submittal. The balance is due at Permit Issuance. Significant changes or additional review cycles (beyond 3 cycles) during the review process may result in adjustments to the final review fees.Roadway (Erosion Control + Transportation)D127,244.50$ WaterA54,361.88$ Wastewater (Sanitary Sewer)B26,809.35$ 2 All prices include labor, equipment, materials, overhead, profit, and taxes. City of Renton Sales Tax is: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 SubmittalPage 2 of 2Ref 8‐H Bond Quantity WorksheetSECTION I PROJECT INFORMATIONUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########UnitReference #PriceUnitQuantity CostBackfill & compaction‐embankmentESC‐17.50$ CY7105,325.00Check dams, 4" minus rockESC‐2SWDM 5.4.6.390.00$ Each2180.00Catch Basin ProtectionESC‐3145.00$ Each4580.00Crushed surfacing 1 1/4" minusESC‐4WSDOT 9‐03.9(3)110.00$ CYDitchingESC‐510.50$ CY75787.50Excavation‐bulkESC‐62.30$ CY300690.00Fence, siltESC‐7SWDM 5.4.3.15.00$ LF7353,675.00Fence, Temporary (NGPE)ESC‐81.75$ LFGeotextile FabricESC‐93.00$ SYHay Bale Silt TrapESC‐100.60$ Each106.00HydroseedingESC‐11SWDM 5.4.2.40.90$ SY40003,600.00Interceptor Swale / DikeESC‐121.15$ LFJute MeshESC‐13SWDM 5.4.2.24.00$ SYLevel SpreaderESC‐142.00$ LFMulch, by hand, straw, 3" deepESC‐15SWDM 5.4.2.12.90$ SYMulch, by machine, straw, 2" deepESC‐16SWDM 5.4.2.12.30$ SYPiping, temporary, CPP, 6"ESC‐1713.75$ LFPiping, temporary, CPP, 8"ESC‐1816.00$ LFPiping, temporary, CPP, 12"ESC‐1920.50$ LFPlastic covering, 6mm thick, sandbaggedESC‐20SWDM 5.4.2.34.60$ SY10004,600.00Rip Rap, machine placed; slopesESC‐21WSDOT 9‐13.1(2)51.00$ CYRock Construction Entrance, 50'x15'x1'ESC‐22SWDM 5.4.4.12,050.00$ Each12,050.00Rock Construction Entrance, 100'x15'x1'ESC‐23SWDM 5.4.4.13,675.00$ EachSediment pond riser assemblyESC‐24SWDM 5.4.5.22,525.00$ Each12,525.00Sediment trap, 5' high berm ESC‐25SWDM 5.4.5.122.00$ LFSed. trap, 5' high, riprapped spillway berm section ESC‐26SWDM 5.4.5.180.00$ LFSeeding, by handESC‐27SWDM 5.4.2.41.15$ SY50005,750.00Sodding, 1" deep, level groundESC‐28SWDM 5.4.2.59.20$ SYSodding, 1" deep, sloped groundESC‐29SWDM 5.4.2.511.50$ SYTESC SupervisorESC‐30125.00$ HR506,250.00Water truck, dust controlESC‐31SWDM 5.4.7160.00$ HR203,200.00UnitReference #PriceUnitQuantity CostEROSION/SEDIMENT SUBTOTAL:39,218.50SALES TAX @ 10.1%3,961.07EROSION/SEDIMENT TOTAL:43,179.57(A)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR EROSION & SEDIMENT CONTROLDescriptionNo.(A)WRITE‐IN‐ITEMS Page 1 of 1Ref 8‐H Bond Quantity WorksheetSECTION II.a EROSION_CONTROLUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostGENERAL ITEMS Backfill & Compaction‐ embankmentGI‐17.00$ CY 78546.005603,920.00Backfill & Compaction‐ trenchGI‐2 10.25$ CY 20205.0040410.00Clear/Remove Brush, by hand (SY)GI‐31.15$ SY 200230.0020002,300.00Bollards ‐ fixedGI‐4 275.00$ EachBollards ‐ removableGI‐5 520.00$ EachClearing/Grubbing/Tree RemovalGI‐6 11,475.00$ Acre 0.11,147.500.33,442.50Excavation ‐ bulkGI‐72.30$ CYExcavation ‐ TrenchGI‐85.75$ CY 20115.0045258.75Fencing, cedar, 6' highGI‐9 23.00$ LF1703,910.00Fencing, chain link, 4'GI‐10 44.00$ LFFencing, chain link, vinyl coated, 6' highGI‐11 23.00$ LFFencing, chain link, gate, vinyl coated, 20' GI‐12 1,600.00$ EachFill & compact ‐ common barrowGI‐13 28.75$ CY 20575.00401,150.00Fill & compact ‐ gravel baseGI‐14 31.00$ CY 25775.0025775.00Fill & compact ‐ screened topsoilGI‐15 44.75$ CYGabion, 12" deep, stone filled mesh GI‐16 74.50$ SYGabion, 18" deep, stone filled mesh GI‐17 103.25$ SYGabion, 36" deep, stone filled meshGI‐18 172.00$ SYGrading, fine, by handGI‐19 2.90$ SYGrading, fine, with graderGI‐20 2.30$ SY 21004,830.00Monuments, 3' LongGI‐21 1,025.00$ EachSensitive Areas SignGI‐22 8.00$ EachSodding, 1" deep, sloped groundGI‐239.25$ SYSurveying, line & gradeGI‐24 975.00$ Day 1975.001975.00Surveying, lot location/linesGI‐25 2,050.00$ Acre 0.51,025.000.51,025.00Topsoil Type A (imported)GI‐26 32.75$ CY 421,375.5020655.00Traffic control crew ( 2 flaggers )GI‐27 137.75$ HR 608,265.00Trail, 4" chipped woodGI‐28 9.15$ SY 1501,372.502001,830.00Trail, 4" crushed cinderGI‐29 10.25$ SYTrail, 4" top courseGI‐30 13.75$ SYConduit, 2"GI‐31 5.75$ LFWall, retaining, concreteGI‐32 63.00$ SFWall, rockeryGI‐33 17.25$ SFSUBTOTAL THIS PAGE:21,436.5020,651.25(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)Page 1 of 3Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)ROAD IMPROVEMENT/PAVEMENT/SURFACINGAC Grinding, 4' wide machine < 1000syRI‐1 34.50$ SY 2107,245.00AC Grinding, 4' wide machine 1000‐2000sy RI‐2 18.25$ SYAC Grinding, 4' wide machine > 2000syRI‐3 11.50$ SYAC Removal/DisposalRI‐4 40.00$ SY 401,600.00Barricade, Type III ( Permanent )RI‐5 64.25$ LFGuard RailRI‐6 34.50$ LFCurb & Gutter, rolledRI‐7 19.50$ LFCurb & Gutter, verticalRI‐8 14.25$ LF 2002,850.00Curb and Gutter, demolition and disposal RI‐9 20.50$ LFCurb, extruded asphaltRI‐10 6.25$ LFCurb, extruded concreteRI‐11 8.00$ LFSawcut, asphalt, 3" depthRI‐12 3.00$ LFSawcut, concrete, per 1" depthRI‐13 5.00$ LF 150750.00Sealant, asphaltRI‐14 2.25$ LFShoulder, gravel, 4" thickRI‐15 17.25$ SYSidewalk, 4" thickRI‐16 43.50$ SY833,610.50Sidewalk, 4" thick, demolition and disposal RI‐17 37.00$ SYSidewalk, 5" thickRI‐18 47.00$ SYSidewalk, 5" thick, demolition and disposal RI‐19 46.00$ SYSign, Handicap RI‐20 97.00$ EachStriping, per stallRI‐21 8.00$ EachStriping, thermoplastic, ( for crosswalk )RI‐22 3.50$ SFStriping, 4" reflectorized lineRI‐23 0.55$ LFAdditional 2.5" Crushed SurfacingRI‐244.15$ SYHMA 1/2" Overlay 1.5" RI‐25 16.00$ SY 3205,120.00HMA 1/2" Overlay 2"RI‐26 20.75$ SYHMA Road, 2", 4" rock, First 2500 SYRI‐27 32.25$ SYHMA Road, 2", 4" rock, Qty. over 2500SY RI‐28 24.00$ SYHMA Road, 4", 6" rock, First 2500 SYRI‐29 51.75$ SYHMA Road, 4", 6" rock, Qty. over 2500 SY RI‐30 42.50$ SYHMA Road, 4", 4.5" ATBRI‐31 43.50$ SY2209,570.00Gravel Road, 4" rock, First 2500 SYRI‐32 17.25$ SYGravel Road, 4" rock, Qty. over 2500 SYRI‐33 11.50$ SYThickened EdgeRI‐34 10.00$ LFSUBTOTAL THIS PAGE:21,175.509,570.00(B)(C)(D)(E)Page 2 of 3Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)PARKING LOT SURFACING No.2" AC, 2" top course rock & 4" borrowPL‐1 24.00$ SY2" AC, 1.5" top course & 2.5" base course PL‐2 32.00$ SY4" select borrowPL‐35.75$ SY1.5" top course rock & 2.5" base coursePL‐4 16.00$ SY2203,520.00SUBTOTAL PARKING LOT SURFACING:3,520.00(B)(C)(D)(E)LANDSCAPING & VEGETATION No.Street TreesLA‐1Median LandscapingLA‐2Right‐of‐Way LandscapingLA‐3Wetland LandscapingLA‐4SUBTOTAL LANDSCAPING & VEGETATION:(B)(C)(D)(E)TRAFFIC & LIGHTING No.SignsTR‐1Street Light System ( # of Poles)TR‐2Traffic SignalTR‐3Traffic Signal ModificationTR‐4SUBTOTAL TRAFFIC & LIGHTING:(B)(C)(D)(E)WRITE‐IN‐ITEMSSUBTOTAL WRITE‐IN ITEMS:STREET AND SITE IMPROVEMENTS SUBTOTAL:42,612.0033,741.25SALES TAX @ 10.1%4,303.813,407.87STREET AND SITE IMPROVEMENTS TOTAL:46,915.8137,149.12(B)(C)(D)(E)Page 3 of 3Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostDRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.)Access Road, R/DD‐130.00$ SY* (CBs include frame and lid)BeehiveD‐2 103.00$ EachThrough‐curb Inlet FrameworkD‐3 460.00$ EachCB Type ID‐4 1,725.00$ Each11,725.00CB Type ILD‐5 2,000.00$ Each12,000.00CB Type II, 48" diameterD‐6 3,500.00$ Each for additional depth over 4' D‐7 550.00$ FTCB Type II, 54" diameterD‐8 4,075.00$ Each for additional depth over 4'D‐9 570.00$ FTCB Type II, 60" diameterD‐10 4,225.00$ Each for additional depth over 4'D‐11 690.00$ FTCB Type II, 72" diameterD‐12 6,900.00$ Each for additional depth over 4'D‐13 975.00$ FTCB Type II, 96" diameterD‐14 16,000.00$ Each for additional depth over 4'D‐15 1,050.00$ FTTrash Rack, 12"D‐16 400.00$ Each 2800.001400.00Trash Rack, 15"D‐17 470.00$ EachTrash Rack, 18"D‐18 550.00$ EachTrash Rack, 21"D‐19 630.00$ EachCleanout, PVC, 4"D‐20 170.00$ EachCleanout, PVC, 6"D‐21 195.00$ EachCleanout, PVC, 8"D‐22 230.00$ EachCulvert, PVC, 4" D‐23 11.50$ LFCulvert, PVC, 6" D‐24 15.00$ LF1001,500.00Culvert, PVC, 8" D‐25 17.00$ LFCulvert, PVC, 12" D‐26 26.00$ LF 1503,900.00Culvert, PVC, 15" D‐27 40.00$ LFCulvert, PVC, 18" D‐28 47.00$ LFCulvert, PVC, 24"D‐29 65.00$ LFCulvert, PVC, 30" D‐30 90.00$ LFCulvert, PVC, 36" D‐31 150.00$ LFCulvert, CMP, 8"D‐32 22.00$ LFCulvert, CMP, 12"D‐33 33.00$ LFSUBTOTAL THIS PAGE:10,700.005,625.00(B)(C)(D)(E)Quantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESPage 1 of 5Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/202236,000.0
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, CMP, 15"D‐34 40.00$ LFCulvert, CMP, 18"D‐35 47.00$ LFCulvert, CMP, 24"D‐36 64.00$ LFCulvert, CMP, 30"D‐37 90.00$ LFCulvert, CMP, 36"D‐38 150.00$ LFCulvert, CMP, 48"D‐39 218.00$ LFCulvert, CMP, 60"D‐40 310.00$ LFCulvert, CMP, 72"D‐41 400.00$ LFCulvert, Concrete, 8"D‐42 48.00$ LFCulvert, Concrete, 12"D‐43 55.00$ LFCulvert, Concrete, 15"D‐44 89.00$ LFCulvert, Concrete, 18"D‐45 100.00$ LFCulvert, Concrete, 24"D‐46 120.00$ LFCulvert, Concrete, 30"D‐47 145.00$ LFCulvert, Concrete, 36"D‐48 175.00$ LFCulvert, Concrete, 42"D‐49 200.00$ LFCulvert, Concrete, 48"D‐50 235.00$ LFCulvert, CPE Triple Wall, 6" D‐51 16.00$ LFCulvert, CPE Triple Wall, 8" D‐52 18.00$ LFCulvert, CPE Triple Wall, 12" D‐53 27.00$ LFCulvert, CPE Triple Wall, 15" D‐54 40.00$ LFCulvert, CPE Triple Wall, 18" D‐55 47.00$ LFCulvert, CPE Triple Wall, 24" D‐56 64.00$ LFCulvert, CPE Triple Wall, 30" D‐57 90.00$ LFCulvert, CPE Triple Wall, 36" D‐58 149.00$ LFCulvert, LCPE, 6"D‐5969.00$ LFCulvert, LCPE, 8"D‐60 83.00$ LFCulvert, LCPE, 12"D‐61 96.00$ LFCulvert, LCPE, 15"D‐62 110.00$ LFCulvert, LCPE, 18"D‐63 124.00$ LFCulvert, LCPE, 24"D‐64 138.00$ LFCulvert, LCPE, 30"D‐65 151.00$ LFCulvert, LCPE, 36"D‐66 165.00$ LFCulvert, LCPE, 48"D‐67 179.00$ LFCulvert, LCPE, 54"D‐68 193.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 2 of 5Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, LCPE, 60"D‐69 206.00$ LFCulvert, LCPE, 72"D‐70 220.00$ LFCulvert, HDPE, 6"D‐71 48.00$ LFCulvert, HDPE, 8"D‐72 60.00$ LFCulvert, HDPE, 12"D‐73 85.00$ LFCulvert, HDPE, 15"D‐74 122.00$ LFCulvert, HDPE, 18"D‐75 158.00$ LFCulvert, HDPE, 24"D‐76 254.00$ LFCulvert, HDPE, 30"D‐77 317.00$ LFCulvert, HDPE, 36"D‐78 380.00$ LFCulvert, HDPE, 48"D‐79 443.00$ LFCulvert, HDPE, 54"D‐80 506.00$ LFCulvert, HDPE, 60"D‐81 570.00$ LFCulvert, HDPE, 72"D‐82 632.00$ LFPipe, Polypropylene, 6"D‐83 96.00$ LFPipe, Polypropylene, 8"D‐84 100.00$ LFPipe, Polypropylene, 12"D‐85 100.00$ LFPipe, Polypropylene, 15"D‐86 103.00$ LFPipe, Polypropylene, 18"D‐87 106.00$ LFPipe, Polypropylene, 24"D‐88 119.00$ LFPipe, Polypropylene, 30"D‐89136.00$ LFPipe, Polypropylene, 36"D‐90 185.00$ LFPipe, Polypropylene, 48"D‐91 260.00$ LFPipe, Polypropylene, 54"D‐92 381.00$ LFPipe, Polypropylene, 60"D‐93 504.00$ LFPipe, Polypropylene, 72"D‐94 625.00$ LFCulvert, DI, 6"D‐95 70.00$ LFCulvert, DI, 8"D‐96 101.00$ LFCulvert, DI, 12"D‐97 121.00$ LFCulvert, DI, 15"D‐98 148.00$ LFCulvert, DI, 18"D‐99175.00$ LFCulvert, DI, 24"D‐100 200.00$ LFCulvert, DI, 30"D‐101 227.00$ LFCulvert, DI, 36"D‐102 252.00$ LFCulvert, DI, 48"D‐103 279.00$ LFCulvert, DI, 54"D‐104 305.00$ LFCulvert, DI, 60"D‐105 331.00$ LFCulvert, DI, 72"D‐106 357.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 3 of 5Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESSpecialty Drainage ItemsDitching SD‐1 10.90$ CYFlow Dispersal Trench (1,436 base+)SD‐3 32.00$ LFFrench Drain (3' depth)SD‐4 30.00$ LFGeotextile, laid in trench, polypropylene SD‐53.40$ SYMid‐tank Access Riser, 48" dia, 6' deep SD‐6 2,300.00$ EachPond Overflow SpillwaySD‐7 18.25$ SYRestrictor/Oil Separator, 12"SD‐8 1,320.00$ EachRestrictor/Oil Separator, 15"SD‐9 1,550.00$ EachRestrictor/Oil Separator, 18"SD‐10 1,950.00$ EachRiprap, placedSD‐11 48.20$ CYTank End Reducer (36" diameter)SD‐12 1,375.00$ EachInfiltration pond testingSD‐13 143.00$ HRPermeable PavementSD‐14Permeable Concrete SidewalkSD‐15Culvert, Box __ ft x __ ftSD‐16SUBTOTAL SPECIALTY DRAINAGE ITEMS:(B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention PondSF‐1Each Detention TankSF‐2Each Detention VaultSF‐3Each Infiltration PondSF‐4Each Infiltration TankSF‐5Each Infiltration VaultSF‐6Each Infiltration TrenchesSF‐7Each Basic Biofiltration SwaleSF‐8Each Wet Biofiltration SwaleSF‐9Each WetpondSF‐10Each WetvaultSF‐11Each Sand FilterSF‐12Each Sand Filter VaultSF‐13Each Linear Sand FilterSF‐14Each Proprietary FacilitySF‐15Each Bioretention FacilitySF‐16Each SUBTOTAL STORMWATER FACILITIES:(B)(C)(D)(E)Page 4 of 5Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESWRITE‐IN‐ITEMS (INCLUDE ON‐SITE BMPs)INFILTRATION TRENCHWI‐1 4,000.00$ 14,000.00STORM FILTERWI‐2 5,000.00$ 15,000.00WI‐3WI‐4WI‐5WI‐6WI‐7WI‐8WI‐9WI‐10WI‐11WI‐12WI‐13WI‐14WI‐15SUBTOTAL WRITE‐IN ITEMS:9,000.00DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:10,700.0014,625.00SALES TAX @ 10.1%1,0701,477.13DRAINAGE AND STORMWATER FACILITIES TOTAL:11,77016,102.13(B)(C)(D)(E)Page 5 of 5Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostConnection to Existing WatermainW‐1 3,400.00$ Each 13,400.00Ductile Iron Watermain, CL 52, 4 Inch Diameter W‐2 58.00$ LFDuctile Iron Watermain, CL 52, 6 Inch Diameter W‐3 65.00$ LFDuctile Iron Watermain, CL 52, 8 Inch Diameter W‐4 75.00$ LFDuctile Iron Watermain, CL 52, 10 Inch Diameter W‐5 80.00$ LFDuctile Iron Watermain, CL 52, 12 Inch Diameter W‐6 145.00$ LF 405,800.0016023,200.00Gate Valve, 4 inch DiameterW‐7 1,225.00$ EachGate Valve, 6 inch DiameterW‐8 1,350.00$ Each 11,350.00Gate Valve, 8 Inch DiameterW‐9 1,550.00$ EachGate Valve, 10 Inch DiameterW‐10 2,100.00$ EachGate Valve, 12 Inch DiameterW‐11 2,500.00$ EachFire Hydrant AssemblyW‐12 5,000.00$ Each 210,000.00Permanent Blow‐Off AssemblyW‐13 1,950.00$ Each 11,950.0011,950.00Air‐Vac Assembly, 2‐Inch DiameterW‐14 3,050.00$ EachAir‐Vac Assembly, 1‐Inch DiameterW‐15 1,725.00$ Each11,725.00Compound Meter Assembly 3‐inch Diameter W‐16 9,200.00$ EachCompound Meter Assembly 4‐inch Diameter W‐17 10,500.00$ EachCompound Meter Assembly 6‐inch Diameter W‐18 11,500.00$ EachPressure Reducing Valve Station 8‐inch to 10‐inch W‐19 23,000.00$ EachWATER SUBTOTAL:22,500.00 26,875.00SALES TAX @ 10.1%2,272.502,714.38WATER TOTAL:24,772.5029,589.38(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR WATERQuantity Remaining (Bond Reduction) (B)(C)Page 1 of 1Ref 8‐H Bond Quantity WorksheetSECTION II.d WATERUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostClean OutsSS‐1 1,150.00$ Each33,450.00Grease Interceptor, 500 gallonSS‐2 9,200.00$ EachGrease Interceptor, 1000 gallonSS‐3 11,500.00$ EachGrease Interceptor, 1500 gallonSS‐4 17,200.00$ EachSide Sewer Pipe, PVC. 4 Inch DiameterSS‐5 92.00$ LFSide Sewer Pipe, PVC. 6 Inch DiameterSS‐6 110.00$ LF19020,900.00Sewer Pipe, PVC, 8 inch DiameterSS‐7 120.00$ LFSewer Pipe, PVC, 12 Inch DiameterSS‐8 144.00$ LFSewer Pipe, DI, 8 inch DiameterSS‐9 130.00$ LFSewer Pipe, DI, 12 Inch DiameterSS‐10 150.00$ LFManhole, 48 Inch DiameterSS‐11 6,900.00$ EachManhole, 54 Inch DiameterSS‐13 6,800.00$ EachManhole, 60 Inch DiameterSS‐15 7,600.00$ EachManhole, 72 Inch DiameterSS‐17 10,600.00$ EachManhole, 96 Inch DiameterSS‐19 16,000.00$ EachPipe, C‐900, 12 Inch DiameterSS‐21 205.00$ LFOutside DropSS‐24 1,700.00$ LSInside DropSS‐25 1,150.00$ LSSewer Pipe, PVC, ____ Inch DiameterSS‐26Lift Station (Entire System)SS‐27LSSANITARY SEWER SUBTOTAL:24,350.00SALES TAX @ 10.1%2,459.35SANITARY SEWER TOTAL:26,809.35(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR SANITARY SEWERQuantity Remaining (Bond Reduction) (B)(C)Page 1 of 1Ref 8‐H Bond Quantity WorksheetSECTION II.e SANITARY SEWERUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430‐7200Date:Name:Project Name: PE Registration No:CED Plan # (LUA):Firm Name:CED Permit # (C):Firm Address:Site Address:Phone No.Parcel #(s):Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal(a)Existing Right‐of‐Way Improvements Subtotal(b)(b)71,688.31$Future Public Improvements Subtotal(c)‐$Stormwater & Drainage Facilities (Public & Private) Subtotal(d)(d)27,872.13$(e)(f)Site RestorationExisting Right‐of‐Way and Storm Drainage ImprovementsMaintenance Bond19,912.09$Bond Reduction2Construction Permit Bond Amount 3Minimum Bond Amount is $10,000.001 Estimate Only ‐ May involve multiple and variable components, which will be established on an individual basis by Development Engineering.2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% willcover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering.* Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton.** Note: All prices include labor, equipment, materials, overhead, profit, and taxes. EST1((b) + (c) + (d)) x 20%‐$ MAINTENANCE BOND */**(after final acceptance of construction)43,179.57$ 71,688.31$ 135,404.6$43,179.57$ ‐$ $ 27,872.13‐$ 175,787.31$P (a) x 100%SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS6/6/2022STEVE WU38852Tendem engineering consultants incR((b x 150%) + (d x 100%))S(e) x 150% + (f) x 100%Bond Reduction: Existing Right‐of‐Way Improvements (Quantity Remaining)2Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2T(P +R ‐ S)Prepared by:Project InformationCONSTRUCTION BOND AMOUNT */**(prior to permit issuance)206‐795‐5674wu868good@outlook.comTran‐Nguyen Development##‐######3343901963FOR APPROVAL########8822 NE 178th St Bothell, WA 98011Page 1 of 1Ref 8‐H Bond Quantity WorksheetSECTION III. BOND WORKSHEETUnit Prices Updated: 01/07/2022Version: 01/07/2022Printed 6/5/2022
M2-05 – Catch Basins
Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed
General Trash &
Debris
Trash or debris which is located immediately
in front of the catch basin opening or is blocking inletting capacity of the basin by more than 10%.
No Trash or debris located
immediately in front of catch basin or on grate opening.
Trash or debris (in the basin) that exceeds 60percent of the sump depth as measured from the bottom of basin to invert of the
lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris surface to the
invert of the lowest pipe.
No trash or debris in the catch basin.
Trash or debris in any inlet or outlet pipe blocking more than 1/3 of its height. Inlet and outlet pipes free of trash or debris.
Dead animals or vegetation that could generate odors that could cause complaints
or dangerous gases (e.g., methane).
No dead animals or vegetation present within
the catch basin.
Sediment Sediment (in the basin) that exceeds
60percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe.
No sediment in the catch
basin
Structure Damage to
Frame and/or Top Slab
Top slab has holes larger than 2 square inches or cracks wider than 1/4 inch (Intent is
to make sure no material is running into basin).
Top slab is free of holes and cracks.
Frame not sitting flush on top slab, i.e., separation of more than 3/4 inch of the frame from the top slab. Frame not securely
attached
Frame is sitting flush on the riser rings or top slab and firmly attached.
Fractures or Cracks in Basin
Walls/Bottom
Maintenance person judges that structure is unsound. Basin replaced or repaired to design standards.
Grout fillet has separated or cracked wider than 1/2 inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence
of soil particles entering catch basin through cracks.
Pipe is regrouted and secure at basin wall.
Settlement/Misalignment If failure of basin has created a safety, function, or design problem. Basin replaced or repaired to design standards.
Vegetation Vegetation growing across and blocking more than 10% of the basin opening. No vegetation blocking opening to basin.
Vegetation growing in inlet/outlet pipe joints
that is more than six inches tall and less than six inches apart.
No vegetation or root growth present.
13
25
Figure 9
Maintenance and Operations Manual
M2-05 – Catch Basins
Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed
Contamination and Pollution
See "Detention Ponds" (No. 1). No pollution present.
Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any open catch basin requires maintenance. Catch basin cover is closed
Locking Mechanism Not Working
Mechanism cannot be opened by one maintenance person with proper tools. Bolts into frame have less than 1/2 inch of thread.
Mechanism opens with
proper tools.
Cover Difficult
to Remove
One maintenance person cannot remove lid
after applying normal lifting pressure. (Intent is keep cover from sealing off access to maintenance.)
Cover can be removed by
one maintenance person.
Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, not securely attached to basin wall, misalignment, rust, cracks, or sharp edges.
Ladder meets design standards and allows maintenance person safe
access.
Metal Grates (If Applicable) Grate opening Unsafe
Grate with opening wider than 7/8 inch. Grate opening meets design standards.
Trash and Debris Trash and debris that is blocking more than20% of grate surface inletting capacity. Grate free of trash and debris.
Damaged or Missing. Grate missing or broken member(s) of the grate. Grate is in place and meets design standards.
M2-06 – Debris Barriers (e.g., Trash Racks)
Maintenance Components
Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed
General Trash and Debris Trash or debris that is plugging more than 20% of the openings in the barrier. Barrier cleared to design flow capacity.
Metal Damaged/
Missing Bars.
Bars are bent out of shape more than 3
inches.
Bars in place with no bends more
than 3/4 inch.
Bars are missing or entire barrier
missing.
Bars in place according to design.
Bars are loose and rust is causing 50%
deterioration to any part of barrier.
Barrier replaced or repaired to
design standards.
Inlet/Outlet Pipe Debris barrier missing or not attached to pipe
Barrier firmly attached to pipe
14
M2-02 - Infiltration
Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected WhenMaintenance Is
Performed
General Trash & Debris See "Detention Ponds" (No. 1). See "Detention Ponds"
(No. 1).
Poisonous/Noxious Vegetation
See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
Contaminants and Pollution
See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
Rodent Holes See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1)
Storage Area Sediment Water ponding in infiltration pond after
rainfall ceases and appropriate time allowed for infiltration. (A percolation test pit or test
of facilityindicates facility is only working at 90% of its designed capabilities. If two inches or more sediment is present,
remove).
Sediment is removed
and/or facility is cleaned so that infiltration system
works according to design.
Filter Bags (if applicable) Filled with
Sediment and Debris
Sediment and debris fill bag more than 1/2 full. Filter bag is replaced or system is redesigned.
Rock Filters Sediment and Debris By visual inspection, little or no water flows through filter during heavy rain storms. Gravel in rock filter is replaced.
Side Slopes of Pond
Erosion See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
EmergencyOverflow Spillwayand Berms over 4 feet
in height.
Tree Growth See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
Piping See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
EmergencyOverflow Spillway
Rock Missing See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
Erosion See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1).
Pre-settling Ponds
and Vaults
Facility or
sumpfilled with Sediment and/or debris
6" or designed sediment trap depth of
sediment.
Sediment is removed.
10
Figure 10
TIR Worksheet
CITY OF RENTON SURFACE WATER DESIGN MANUAL
2017 City of Renton Surface Water Design Manual 12/12/2016 8-A-1
REFERENCE 8-A
TECHNICAL INFORMATION REPORT (TIR)
WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Owner _____________________________
Phone ___________________________________
Address __________________________________
_________________________________________
Project Engineer ___________________________
Company _________________________________
Phone ___________________________________
Project Name __________________________
CED Permit # ________________________
Location Township ________________
Range __________________
Section _________________
Site Address __________________________
_____________________________________
Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS
Land Use (e.g., Subdivision / Short Subd.)
Building (e.g., M/F / Commercial / SFR)
Grading
Right-of-Way Use
Other _______________________
DFW HPA
COE 404
DOE Dam Safety
FEMA Floodplain
COE Wetlands
Other ________
ShorelineManagement
StructuralRockery/Vault/_____
ESA Section 7
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report Site Improvement Plan (Engr. Plans)
Type of Drainage Review
(check one):
Date (include revision
dates):
Date of Final:
Full
Targeted
Simplified
Large Project
Directed
____________________________________
__________________
Plan Type (check
one):
Date (include revision
dates):
Date of Final:
Full
Modified
Simplified
____________________________________
__________________
Long & Vu Tran Nguyen
11904 SE 228th PL Kent WA 98031
206-384-3690
STEVE WU
TEC INC
206-795-5674
TRAN-NGUYEN DEVELOPMENT
LUA 21-000206
23N
5E
5
2309 ABERDEEN AVE NE
RENTON WA 98056
X
REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-2
Part 6 SWDM ADJUSTMENT APPROVALS
Type (circle one): Standard / Blanket
Description: (include conditions in TIR Section 2)
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
Approved Adjustment No. ______________________ Date of Approval: _______________________
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes / No
Start Date: _______________________
Completion Date: _______________________
Describe: _________________________________
_________________________________________
_________________________________________
Re: SWDM Adjustment No. ________________
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan: ____________________________________________________________________
Special District Overlays: ______________________________________________________________
Drainage Basin: _____________________________________________________________________
Stormwater Requirements: _____________________________________________________________
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
River/Stream ________________________
Lake ______________________________
Wetlands ____________________________
Closed Depression ____________________
Floodplain ___________________________
Other _______________________________
_______________________________
Steep Slope __________________________
Erosion Hazard _______________________
Landslide Hazard ______________________
Coal Mine Hazard ______________________
Seismic Hazard _______________________
Habitat Protection ______________________
_____________________________________Aquifer Protection Zone 2
Lake Washington
Core #1 to Core #9
REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-3
Part 10 SOILS
Soil Type
______________________
______________________
______________________
______________________
Slopes
________________________
________________________
________________________
________________________
Erosion Potential
_________________________
_________________________
_________________________
_________________________
High Groundwater Table (within 5 feet)
Other ________________________________
Sole Source Aquifer
Seeps/Springs
Additional Sheets Attached
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE
Core 2 – Offsite Analysis_________________
Sensitive/Critical Areas__________________
SEPA________________________________
LID Infeasibility________________________
Other________________________________
_____________________________________
LIMITATION / SITE CONSTRAINT
_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
Additional Sheets Attached
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet
per Threshold Discharge Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply):
Discharge at Natural Location Number of Natural Discharge Locations:
Offsite Analysis Level: 1 / 2 / 3 dated:__________________
Flow Control (include facility
summary sheet)
Standard: _______________________________
or Exemption Number: ____________
On-site BMPs: _______________________________
Conveyance System Spill containment located at: _____________________________
Erosion and Sediment Control /
Construction Stormwater Pollution
Prevention
CSWPP/CESCL/ESC Site Supervisor: _____________________
Contact Phone: _________________________
After Hours Phone: _________________________
Level 1
Loamy Sand 5-15%Yes
March 9, 2021
During Matching forested conditions
Infiltation trenches and bioretention cell
REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-4
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet
per Threshold Discharge Area)
Maintenance and Operation Responsibility (circle one): Private / Public
If Private, Maintenance Log Required: Yes / No
Financial Guarantees and Liability Provided: Yes / No
Water Quality (include facility
summary sheet)
Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog
or Exemption No. _______________________
Special Requirements (as applicable):
Area Specific Drainage
Requirements
Type: SDO / MDP / BP / Shared Fac. / None
Name: ________________________
Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None
100-year Base Flood Elevation (or range): _______________
Datum:
Flood Protection Facilities Describe:
Source Control
(commercial / industrial land use)
Describe land use:
Describe any structural controls:
Oil Control High-Use Site: Yes / No
Treatment BMP: _________________________________
Maintenance Agreement: Yes / No
with whom? _____________________________________
Other Drainage Structures
Describe:
1
REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-5
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
Clearing Limits
Cover Measures
Perimeter Protection
Traffic Area Stabilization
Sediment Retention
Surface Water Collection
Dewatering Control
Dust Control
Flow Control
Control Pollutants
Protect Existing and Proposed BMPs/Facilities
Maintain Protective BMPs / Manage Project
MINIMUM ESC REQUIREMENTS
AFTER CONSTRUCTION
Stabilize exposed surfaces
Remove and restore Temporary ESC Facilities
Clean and remove all silt and debris, ensure operation of Permanent BMPs/Facilities, restore
operation of BMPs/Facilities as necessary
Flag limits of sensitive areas and open space
preservation areas
Other _______________________
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch)
Flow Control Type/Description Water Quality Type/Description
Detention
Infiltration
Regional Facility
Shared Facility
On-site BMPs
Other
________________
________________
________________
________________
________________
________________
Vegetated Flowpath
Wetpool
Filtration
Oil Control
Spill Control
On-site BMPs
Other
________________
________________
________________
________________
________________
________________
________________
Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS
Drainage Easement
Covenant
Native Growth Protection Covenant
Tract
Other ____________________________
Cast in Place Vault
Retaining Wall
Rockery > 4′ High
Structural on Steep Slope
Other _______________________________
Bioretention Cell
Trenches
REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-6
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information provided here is accurate.
____________________________________________________________________________________ Signed/Date
12/26/2022
26
APPENDIX A
Geotechnical Report
27
APPENDIX B
Drainage, Cross-sections and Details Plans
DATE:
FIELDBOOK:
DRAWING NO:
PAGE:
SHEET: OF:
SCALE:
DESIGNED:
DRAWN:
CHECKED:
APPROVED:NO.REVISION BY DATE APPR
FILENAME:SURVEYED:
VERTICAL: NAVD 1988
IF NOT ONE INCH
ONE INCH
AT FULL SCALE
HORIZONTAL: NAD 1983/1991
SCALE ACCORDINGLY
DATUM
Planning/Building/Public Works Dept.
CITY OF
RENTON
IN COMPLIANCE WITH CITY OF RENTON STANDARDS
DRAINAGE DETAILS PLAN
TRAN-NGUYEN DEVELOPMENT
C-19.0
19TED-40-4210R-421013
28
6/16/2022
28
APPENDIX C
On-site BMPs Design Criteria
StormFilter Catch Basin Basic treatment level WQ flowrate = 0.01 cfs
Peak (100yr) flow = <1.0 cfs (1) 18” tall ZPG cartridges in a SFCB-Steel - Required drop of 2.3’ from rim to outlet invert Total structure depth of 3.75’ Permanent pool located 1’ below structure rim
29
APPENDIX D
Declaration of Covenant for Maintenance and Inspection of
On-site BMPs
Page 1 of ___
Return Address:
City Clerk’s Office
City of Renton
1055 S Grady Way
Renton, WA 98057
DECLARATION OF COVENANT
FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND
ON-SITE BMPS
Grantor:
Grantee: City of Renton, a Washington municipal corporation
Legal Description:
Assessor's Tax Parcel ID#:
IN CONSIDERATION of the approved City of Renton (check one of the following)
Residential Building Permit Commercial Building Permit
Clearing and Grading Permit Civil Construction or Utility Permit
for Permit(s)_____________________ (Construction/Building/Utility Permit #) relating to the real property
("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby
covenants (covenant) with the City of Renton (“City of Renton” or “City”), a municipal corporation
of the state of Washington, that he/she (they) will observe, consent to, and abide by the conditions
and obligations set forth and described in Paragraphs 1 through 9 below with regard to the
Property, and hereby grants (grant) an easement as described in Paragraphs 2 and 3. Grantor(s)
hereby grants (grant), covenants (covenant), and agrees (agree) as follows:
1.The Grantor(s) or his/her (their) successors in interest and assigns ("Owners ") shall at their own
cost, operate, maintain, and keep in good repair, the Property's drainage facilities constructed
as required in the approved construction plans and specifications __________________ (Project
Plan #) on file with the City of Renton and submitted to the City of Renton for the review and
approval of permit(s) _____________________________ (Construction/Building/Utility Permit #). The
Property's drainage facilities are shown and/or listed on Exhibit A – Site Plan. The Property’s
drainage facilities shall be maintained in compliance with the operation and maintenance
schedule included and attached herein as Exhibit B – Operations and Maintenance. Drainage
facilities include pipes, channels, flow control facilities, water quality facilities, on-site best
management practices (BMPs) and other engineered structures designed to manage and/or
Page 2 of ___
treat stormwater on the Property. On-site BMPs include dispersion and infiltration devices,
bioretention, permeable pavements, rainwater harvesting systems, tree retention credit,
reduced impervious surface footprint, vegetated roofs and other measures designed to mimic
pre-developed hydrology and minimize stormwater runoff on the Property.
2.City of Renton shall have the right to ingress and egress over those portions of the Property
necessary to perform inspections of the stormwater facilities and BMPs and conduct
maintenance activities specified in this Declaration of Covenant and in accordance with the
Renton Municipal Code. City of Renton shall provide at least thirty (30) days’ written notice to
the Owners that entry on the Property is planned for the inspection of drainage facilities. After
the thirty (30) days, the Owners shall allow the City of Renton to enter for the sole purpose of
inspecting drainage facilities. 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 drainage facilities 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 (15) days of receiving the City’s notice of inspection. Within thirty (30) days of giving this
notice, the Owners, or 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 drainage facilities without further notice.
3.If City of Renton determines from its inspection, or from an engineer’s report provided in
accordance with Paragraph 2, that maintenance, repair, restoration, and/or mitigation work is
required to be done to any of the drainage facilities, City of Renton shall notify the Owners of
the specific maintenance, repair, restoration, and/or mitigation work (“Work”) required
pursuant to the Renton Municipal Code. The City shall also set a reasonable deadline for the
Owners to complete the Work, or to provide 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 drainage facilities unless an engineer’s report has been provided verifying completion of
the Work. If the Work is not completed within the time frame set by the City, the City may
initiate an enforcement action and/or perform the Work and hereby is given access to the
Property for such purposes. Written notice will be sent to the Owners stating the City’s
intention to perform such Work. This Work will not commence until at least seven (7) days after
such notice is mailed. If, within the sole discretion of the City, there exists an imminent or
present danger, the seven (7) day notice period will be waived and Work will begin
immediately.
4.The Owners shall assume all responsibility for the cost of any Work, or any measures taken by
the City to address conditions as described in Paragraph 3. Such responsibility shall include
reimbursement to the City within thirty (30) days of the receipt of the invoice for any such Work
performed. Overdue payments will require payment of interest at the maximum legal rate
allowed by RCW 19.52.020 (currently twelve percent (12%)). If the City initiates legal action to
enforce this agreement, the prevailing party in such action is entitled to recover reasonable
litigation costs and attorney’s fees.
5.The Owners are required to obtain written approval from City of Renton prior to filling, piping,
cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated
stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any
alterations or modifications to the drainage facilities referenced in this Declaration of Covenant.
Page 3 of ___
6.Any notice or consent required to be given or otherwise provided for by the provisions of this
Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified
Mail, return receipt requested.
7.With regard to the matters addressed herein, this agreement constitutes the entire agreement
between the parties, and supersedes all prior discussions, negotiations, and all agreements
whatsoever whether oral or written.
8.This Declaration of Covenant is intended to protect the value and desirability and promote
efficient and effective management of surface water drainage of the real property described
above, and shall inure to the benefit of all the citizens of the City of Renton and its successors
and assigns. This Declaration of Covenant shall run with the land and be binding upon
Grantor(s), and Grantor's(s') successors in interest, and assigns.
9.This Declaration of Covenant may be terminated by execution of a written agreement by the
Owners and the City that is recorded by King County in its real property records.
IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of
Drainage Facilities is executed this _____ day of ____________________, 20_____.
GRANTOR, owner of the Property GRANTOR, owner of the Property
STATE OF WASHINGTON )
COUNTY OF KING )ss.
On this day personally appeared before me:
, to me known to be the individual(s)
described in and who executed the within and foregoing instrument and acknowledged that they
signed the same as their free and voluntary act and deed, for the uses and purposes therein stated.
Given under my hand and official seal this _____ day of ___________________, 20_____.
Printed name
Notary Public in and for the State of
Washington, residing at
My appointment expires
Page 4 of ___
Exhibit A – Site Plan
Please replace this page with “Exhibit A - Site Plan” that is prepared in accordance with
the Renton Surface Water Design Manual Appendix C Section C.4.
See Example Declaration of Covenant for help preparing this document.
Page 5 of ___
Exhibit B – Operations and Maintenance
Please replace this page with all applicable “Exhibit B – Operations and Maintenance”
Details referenced in the Renton Surface Water Design Manual Reference 8-M that are
proposed to be constructed on the project site.
See Example Declaration of Covenant for help preparing this document.
Page 6 of ___
Exhibit C – Legal Description
Please replace this page with “Exhibit C – Legal Description” if the property legal
description does not fit within the space provided on Page 1 of the Declaration of
Covenant. Add reference to “Exhibit C” in the legal description field on page 1 of the
Declaration of Covenant document.
32
APPENDIX E
Continuous Model Out for Infiltration Trenches
————————————————————————————————— MGS FLOOD PROJECT REPORT
Program Version: MGSFlood 4.52 Program License Number: 300210203 Project Simulation Performed on: 03/12/2022 4:19 PM Report Generation Date: 03/12/2022 4:20 PM
—————————————————————————————————
Input File Name: Infiltration trench.fld
Project Name: Renton Analysis Title: Infiltration Trench
Comments: ———————————————— PRECIPITATION INPUT ————————————————
Computational Time Step (Minutes): 15
Extended Precipitation Time Series Selected
Climatic Region Number: 32
Full Period of Record Available used for Routing Precipitation Station : 99003805 Seattle 38 in_5min 10/01/1939-10/01/2097 Evaporation Station : 991038 Seattle 38 in MAP Evaporation Scale Factor : 0.750
HSPF Parameter Region Number: 1
HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) ***************
********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.092 0.092
Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.092 0.092 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) --------
Till Forest 0.092 ---------------------------------------------- Subbasin Total 0.092
----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) --------
Impervious 0.092 ---------------------------------------------- Subbasin Total 0.092 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0
************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1
------------------------------------------ Link Name: New Infilt Trench Lnk1
Link Type: Infiltration Trench Downstream Link: None
Trench Type : Trench on Embankment Sideslope
Trench Length (ft) : 20.00 Trench Width (ft) : 10.00
Trench Depth (ft) : 2.00 Trench Bottom Elev (ft) : 100.00
Trench Rockfill Porosity (%) : 30.00
Hydraulic Conductivity (in/hr) : 6.00 Massmann Regression Used to Estimate Hydralic Gradient
Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low
Maintenance : Average or Better
**********************FLOOD FREQUENCY AND DURATION STATISTICS*******************
----------------------SCENARIO: PREDEVELOPED
Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1
Number of Links: 1 ***********Groundwater Recharge Summary *************
Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 15.011
_____________________________________ Total: 15.011 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) -----------------------------------------------------------------------------------------------
Subbasin: Subbasin 1 0.000 Link: New Infilt Trench Ln 38.958 _____________________________________ Total: 38.958
Total Predevelopment Recharge is Less than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.095 ac-ft/year, Post Developed: 0.247 ac-ft/year ***********Water Quality Facility Data *************
----------------------SCENARIO: PREDEVELOPED
Number of Links: 0
----------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
********** Link: New Infilt Trench Lnk1 **********
Infiltration/Filtration Statistics--------------------
Inflow Volume (ac-ft): 38.96 Inflow Volume Including PPT-Evap (ac-ft): 38.96
Total Runoff Infiltrated (ac-ft): 38.96, 100.00% Total Runoff Filtered (ac-ft): 0.00, 0.00%
Primary Outflow To Downstream System (ac-ft): 0.00 Secondary Outflow To Downstream System (ac-ft): 0.00
Percent Treated (Infiltrated+Filtered)/Total Volume: 100.00%
***********Compliance Point Results *************
Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Link: New Infilt Trench Lnk1
*** Point of Compliance Flow Frequency Data ***
Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs)
---------------------------------------------------------------------------------------------------------------------- 2-Year 1.992E-03 2-Year 0.000 5-Year 3.111E-03 5-Year 0.000 10-Year 3.987E-03 10-Year 0.000 25-Year 5.275E-03 25-Year 0.000 50-Year 5.548E-03 50-Year 0.000
100-Year 7.858E-03 100-Year 0.000 200-Year 1.236E-02 200-Year 9.203E-03 500-Year 1.833E-02 500-Year 2.160E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals **** Flow Duration Performance **** Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): -100.0% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%): -100.0% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -61.0% PASS
Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS
------------------------------------------------------------------------------------------------- MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS -------------------------------------------------------------------------------------------------
**** LID Duration Performance ****
Excursion at Predeveloped 8%Q2 (Must be Less Than 0%): -100.0% PASS Maximum Excursion from 8%Q2 to 50%Q2 (Must be Less Than 0%): -100.0% PASS
-------------------------------------------------------------------------------------------------
MEETS ALL LID DURATION DESIGN CRITERIA: PASS -------------------------------------------------------------------------------------------------
————————————————————————————————— MGS FLOOD PROJECT REPORT
Program Version: MGSFlood 4.52 Program License Number: 200210003 Project Simulation Performed on: 05/09/2022 3:36 PM Report Generation Date: 05/09/2022 3:37 PM
—————————————————————————————————
Input File Name: Infiltration trench - Access Road.fld
Project Name: Renton Analysis Title: Infiltration Trench
Comments: ———————————————— PRECIPITATION INPUT ————————————————
Computational Time Step (Minutes): 15
Extended Precipitation Time Series Selected
Climatic Region Number: 32
Full Period of Record Available used for Routing Precipitation Station : 99003805 Seattle 38 in_5min 10/01/1939-10/01/2097 Evaporation Station : 991038 Seattle 38 in MAP Evaporation Scale Factor : 0.750
HSPF Parameter Region Number: 1
HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) ***************
********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.104 0.104
Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.104 0.104 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) --------
Till Forest 0.104 ---------------------------------------------- Subbasin Total 0.104
----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1
---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) --------
Impervious 0.104 ---------------------------------------------- Subbasin Total 0.104
************************* LINK DATA *******************************
----------------------SCENARIO: PREDEVELOPED Number of Links: 0
************************* LINK DATA *******************************
----------------------SCENARIO: POSTDEVELOPED Number of Links: 1
------------------------------------------ Link Name: New Infilt Trench Lnk1
Link Type: Infiltration Trench Downstream Link: None
Trench Type : Trench on Embankment Sideslope
Trench Length (ft) : 22.00 Trench Width (ft) : 10.00
Trench Depth (ft) : 2.00 Trench Bottom Elev (ft) : 100.00
Trench Rockfill Porosity (%) : 30.00
Hydraulic Conductivity (in/hr) : 6.00 Massmann Regression Used to Estimate Hydralic Gradient
Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low
Maintenance : Average or Better
**********************FLOOD FREQUENCY AND DURATION STATISTICS*******************
----------------------SCENARIO: PREDEVELOPED
Number of Subbasins: 1 Number of Links: 0
----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1
Number of Links: 1
***********Groundwater Recharge Summary *************
Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 17.006
_____________________________________ Total: 17.006 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) -----------------------------------------------------------------------------------------------
Subbasin: Subbasin 1 0.000 Link: New Infilt Trench Ln 44.136 _____________________________________ Total: 44.136
Total Predevelopment Recharge is Less than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.108 ac-ft/year, Post Developed: 0.279 ac-ft/year ***********Water Quality Facility Data *************
----------------------SCENARIO: PREDEVELOPED
Number of Links: 0
----------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
********** Link: New Infilt Trench Lnk1 **********
Basic Wet Pond Volume (91% Exceedance): 483. cu-ft
Computed Large Wet Pond Volume, 1.5*Basic Volume: 725. cu-ft
2-Year Discharge Rate : 0.000 cfs
15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.01 cfs
Off-line Design Discharge Rate (91% Exceedance): 0.01 cfs
Time to Infiltrate 91% Treatment Volume, (Hours): 3.66
Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 44.14 Inflow Volume Including PPT-Evap (ac-ft): 44.14
Total Runoff Infiltrated (ac-ft): 44.14, 100.00% Total Runoff Filtered (ac-ft): 0.00, 0.00%
Primary Outflow To Downstream System (ac-ft): 0.00 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 100.00%
***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Link: New Infilt Trench Lnk1
*** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs)
---------------------------------------------------------------------------------------------------------------------- 2-Year 2.257E-03 2-Year 0.000 5-Year 3.524E-03 5-Year 0.000 10-Year 4.516E-03 10-Year 0.000
25-Year 5.976E-03 25-Year 0.000 50-Year 6.285E-03 50-Year 0.000
100-Year 8.902E-03 100-Year 1.087E-02 200-Year 1.400E-02 200-Year 1.625E-02 500-Year 2.077E-02 500-Year 2.309E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals
**** Flow Duration Performance **** Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): -100.0% PASS
Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%): -100.0% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -2.6% PASS
Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS
------------------------------------------------------------------------------------------------- MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS
-------------------------------------------------------------------------------------------------
**** LID Duration Performance ****
Excursion at Predeveloped 8%Q2 (Must be Less Than 0%): -100.0% PASS Maximum Excursion from 8%Q2 to 50%Q2 (Must be Less Than 0%): -100.0% PASS
-------------------------------------------------------------------------------------------------
MEETS ALL LID DURATION DESIGN CRITERIA: PASS -------------------------------------------------------------------------------------------------
32
APPENDIX F
Stormwater Pollution Prevention Plan
(SWPPP)
extracted
Construction Stormwater General Permit
Stormwater Pollution Prevention Plan
(SWPPP)
for
2309 Aberdeen
Renton, WA 98056
Prepared for:
The Washington State Department of Ecology
NORTHWEST REGIONAL OFFICE
Permittee / Owner Developer Operator / Contractor
Long Ngugyen Wei Huang
Update as necessary.
Certified Erosion and Sediment Control Lead (CESCL)
Name Organization Contact Phone Number
JIM WU TEC 206-383-8867
SWPPP Prepared By
Name Organization Contact Phone Number
STEVE WU TEC 206-795-5674
SWPPP Preparation Date
08/08/2021
Project Construction Dates
Activity / Phase Start Date End Date
4/1/2021 12/31/2022
Page | 1
Table of Contents
1 Project Information ................................................................................................................. 4
1.1 Existing Conditions ......................................................................................................... 4
1.2 Proposed Construction Activities .................................................................................... 4
2 Construction Stormwater Best Management Practices (BMPs) ..............................................
2.1 The 13 Elements ............................................................................................................ 6
2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits .......................................... 6
2.1.2 Element 2: Establish Construction Access .............................................................. 7
2.1.3 Element 3: Control Flow Rates ................................................................................ 8
2.1.4 Element 4: Install Sediment Controls ...................................................................... 9
2.1.5 Element 5: Stabilize Soils ...................................................................................... 10
2.1.6 Element 6: Protect Slopes ..................................................................................... 11
2.1.7 Element 7: Protect Drain Inlets .............................................................................. 12
2.1.8 Element 8: Stabilize Channels and Outlets ........................................................... 13
2.1.9 Element 9: Control Pollutants ................................................................................ 14
2.1.10 Element 10: Control Dewatering ........................................................................... 16
2.1.11 Element 11: Maintain BMPs .................................................................................. 17
2.1.12 Element 12: Manage the Project ........................................................................... 18
2.1.13 Element 13: Protect on-site Stormwater Management BMPs for Runoff from roof
and other Surface ................................................................................................................ 18
3 Pollution Prevention Team ................................................................................................... 19
4 Monitoring and Sampling Requirements .............................................................................. 20
4.1 Site Inspection .............................................................................................................. 20
4.2 Stormwater Quality Sampling ....................................................................................... 20
4.2.1 Turbidity Sampling ................................................................................................. 20
4.2.2 pH Sampling .......................................................................................................... 22
5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies ......................... 23
5.1 303(d) Listed Waterbodies ........................................................................................... 23
5.2 TMDL Waterbodies ....................................................................................................... 23
6 Reporting and Record Keeping ........................................................................................... 24
6.1 Record Keeping ............................................................................................................ 24
6.1.1 Site Log Book ........................................................................................................ 24
6.1.2 Records Retention ................................................................................................. 24
6.1.3 Updating the SWPPP ............................................................................................ 24
6.2 Reporting ...................................................................................................................... 25
6.2.1 Discharge Monitoring Reports ............................................................................... 25
Page | 2
6.2.2 Notification of Noncompliance ............................................................................... 25
List of Tables
Table 1 – pH-Modifying Sources ................................................................................................. 14
Table 2 – Management ............................................................................................................... 18
Table 3 – Team Information ........................................................................................................ 19
Table 4 – pH Sampling Method .................................................................................................. 22
List of Appendices
Appendix/Glossary
A. Site Map
B. BMP Detail
C. Site Inspection Form
D. Sediment Trap Calculation
Page | 3
List of Acronyms and Abbreviations
Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies
BFO Bellingham Field Office of the Department of Ecology
BMP(s) Best Management Practice(s)
CESCL Certified Erosion and Sediment Control Lead
CO2 Carbon Dioxide
CRO Central Regional Office of the Department of Ecology
CSWGP Construction Stormwater General Permit
CWA Clean Water Act
DMR Discharge Monitoring Report
DO Dissolved Oxygen
Ecology Washington State Department of Ecology
EPA United States Environmental Protection Agency
ERO Eastern Regional Office of the Department of Ecology
ERTS Environmental Report Tracking System
ESC Erosion and Sediment Control
GULD General Use Level Designation
NPDES National Pollutant Discharge Elimination System
NTU Nephelometric Turbidity Units
NWRO Northwest Regional Office of the Department of Ecology
pH Power of Hydrogen
RCW Revised Code of Washington
SPCC Spill Prevention, Control, and Countermeasure
su Standard Units
SWMMEW Stormwater Management Manual for Eastern Washington
SWMMWW Stormwater Management Manual for Western Washington
SWPPP Stormwater Pollution Prevention Plan
TESC Temporary Erosion and Sediment Control
SWRO Southwest Regional Office of the Department of Ecology
TMDL Total Maximum Daily Load
VFO Vancouver Field Office of the Department of Ecology
WAC Washington Administrative Code
WSDOT Washington Department of Transportation
WWHM Western Washington Hydrology Model
Page | 4
Project Information
Project/Site Name: Ning Workshop Street/Location: 221 Nyden Farms Rd
City: Medina State: WA Zip code: 98258 Subdivision: Receiving waterbody: Lake Stevens
Existing Conditions
Total acreage (including support activities such as off-site equipment staging yards, material
storage areas, borrow areas).
Total acreage: 0.857 Disturbed acreage: 0.71
Existing structures: No existing structure on site. Landscape topography: Vegegations, tress, and brushes
Drainage patterns: On site infiltration or sheets flows to the frontage road. Existing Vegetation: Well maintenance grass, brushes, and some trees. Critical Areas (wetlands, streams, high erosion
risk, steep or difficult to stabilize slopes):
No sensitive areas on site.
List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the
receiving waterbody: N/A
Proposed Construction Activities
Description of site development (example: subdivision):
This project will subdivide the existing lot into three lots. The scope of this project will include
gradation, construction of driveway, bioretention cell, installation of utilities, and build the
sidewalk with planter along the property line on Aberdeen Ave NE. The site gradation will not
impact adjacent to the neiborthood properties. existing contour is not expected to alter. No
impact to the wetland.
Description of construction activities (example: site preparation, demolition, excavation):
Construction activities will include site preparation, TESC installation, site grade, excavation for
the bioretention cell, and construct a 20’ width with 149’ in length driveway to connect with
Aberdeen Ave NE.
Description of site drainage including flow from and onto adjacent properties. Must be
consistent with Site Map in Appendix A:
No on site flow or onto adjacent properties. The site is covered with vegetations, on site
infiltration is implement. The site slopes gently downward from west to east and northeast at
magnitudes of 5 to 10 percent.
Page | 5
Description of final stabilization (example: extent of revegetation, paving, landscaping):
After the site graded, 20’ access paved road build, bioretention cell built, and all utilites are
installed run off. The whole site will be covered by vegetations and trees. No bare ground will be
exposed to the air. The bioretention cell will collect the access road run offs.
Contaminated Site Information:
Proposed activities regarding contaminated soils or groundwater (example: on-site treatment
system, authorized sanitary sewer discharge):
No on site contaminated materials are expected after completion of this project. sanitary sewer
will connect with exiting setics on site.
Page | 6
The SWPPP is a living document reflecting current conditions and changes throughout the life
of the project. These changes may be informal (i.e., hand-written notes and deletions). Update
the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design.
The 13 Elements
Element 1: Preserve Vegetation / Mark Clearing Limits
There are no wetlands, streams or sensitive areas near the clearing limits. To protect adjacent properties
and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked
before land-disturbing activities begin. Existing vegetation (trees, bushes, shrubs, grasses) shall be
preserved when removal is not necessary for the construction of the project. The contractor is required to
survey, stake, and flag the clearing limits shown in the plans and/or areas not to be disturbed including
easements, setbacks, sensitive and critical areas and their buffers, and drainage courses before any
clearing or grubbing can begin.
List and describe BMPs: Silt Fence will be installed prior any construction activites, high visible fence
will be installed around the trees.
Installation Schedules: Prior any construction activities.
Inspection and Maintenance plan: Inspect silt fence once a week, replace any boken fence or any wear
out.
Responsible Staff: Jim W
Page | 7
Element 2: Establish Construction Access
The risk associated with establishing the construction access to the project is considered very
low. The contractor is require to stabilize identified construction access points and need to be
installed prior to major grading operations. Construction vehicles entering and exiting the project
site and staging areas will use only identified access points.
Sediment track out onto the street will be eliminated by effective implementation of construction
road and entrance stabilization measures installed per Ecology BMP C105 Stabilized
Construction Entrance. The construction entrance will be stabilized with quarry spalls/crushed
rock or construction entrance plates to reduce the amount of sediment transported onto paved
roads by vehicles or equipment.
Properly maintained stabilized construction entrances and construction entrance plates should
prevent track out under normal conditions. If track out is observed at any time onto offsite
pavement, the road will be thoroughly cleaned as frequently as necessary. At a minimum, the
streets will be cleaned at the end of each working day. Sediment will be removed from the roads
by shoveling or sweeping. Soils collected by the street sweeper and any water used by the
sweeper equipment are considered to be contaminated and will be collected and disposed of at an
approved disposal facility.
List and describe BMPs: Construction Entrance will be implement for this job site prior any construction
activity. Street cleaning will be implement if necessary.
Installation Schedules: Prior any construction activies.
Inspection and Maintenance plan: check the construction entrance as least once a week.
Responsible Staff: Jim Wu
Page | 8
Element 3: Control Flow Rates
The riskes associated with uncontrolled flow rates for this project is very low. The entire project site is
covered by vegations and surrounding with private proerities, each with its own stormwater runoff
drainage system draining to the public storm water main and on site infiltration.
Will you construct stormwater retention and/or detention facilities?
No. Detention is not required for this project.
Will you use permanent infiltration ponds or other low impact development (example: rain
gardens, bio-retention, porous pavement) to control flow during construction?
infiltration trench will be used as temporary on site BMP as needed. No permanent
infiltration pond or other low impact development BMP will be insalled after completion of the
project.
List and describe BMPs: Temporary infiltration trench, sediment traps.
Installation Schedules: During construction
Inspection and Maintenance plan: use DOE manual as guildlines
Responsible Staff: Jim Wu
Page | 9
Element 4: Install Sediment Controls
Sediment control BMPs will be installed prior to soil disturbing activities, where feasible. Inlet
protection will be provided for all existing and proposed catch basins in the project area and it
vicinity to reduce the amount of sediment entering the conveyance system. . Any temporarily
unworked or exposed soil on the project site will be covered by plastic covering or other
approved equivalent to prevent the release of sediment into air or conveyance system.
Construction stormwater runoff that has not contacted disturbed areas or that passes over fully
stabilized areas will be protected from contamination, and where practical will be passed directly
through the project site for discharge to the appropriate conveyance system as per permit
requirement. Silt fence will also be used along the perimeter of the construction activities to help
stabilize soils. The silt fence installation will be coordinated with installation of security fence,
construction or other type of fencing. Any offsite flow (run-on) onto construction site will be
diverted to downstream natural flow path using temporary curbs, asphalt berms or sand bags. To
the maximum extent possible, sheet flow will be maintained, as sheet flow greatly reduces the
potential for erosion and sediment transport.
Silt fence and inlet protection will be used to settle out the sediment before discharging to an
approved discharge locations. Street sweeping by dry sweeping, manual shoveling or street
sweeper/scrubber will be employed to remove the sediment on roads. Water may be used for
fugitive dust control on the project site.
List and describe BMPs: Dust control, Materials on Hand, Nets and Blankets, Plastic covering. Storm
Drain Inlet Protection, sediment trap will be established during construction.
Installation Schedules: Prior construction and during construction for all BMPs listed above.
Inspection and Maintenance plan: Check all BMPs at least once a week.
Responsible Staff: JW
Page | 10
Element 5: Stabilize Soils
The risks associated with stabilizing the on-site soils are considered moderate. This project is
scheduled to disturb approximately 0.7 acres of soil beginning in june 2022 and construction will
last for 3 months. The amount of exposed soil will be limited. The amount of exposed or
unworked soil in the working area will be limited to the amounts specified in the WSDOT
Standard Specification 8-01.3(1).
West of the Cascade Mountains Crest
Season Dates Number of Days Soils Can be Left Exposed
During the Dry Season May 1 – September 30 7 days
During the Wet Season October 1 – April 30 2 days
Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on
the weather forecast.
Anticipated project dates: Start date: October 2021. End date: June, 2022.
Will you construct during the wet season?
No. No excavation will be anticipated during the wet seasion.
List and describe BMPs: Materials on Hand, Nets and blankets, Plastic Covering, Top soiling, Dust
Control, Schedule. Seeding.
Installation Schedules: Prior construction activities and during construction.
Inspection and Maintenance plan: Check all BMPs at least once a week.
Responsible Staff: JW.
Page | 11
Element 6: Protect Slopes
The risk associated with the protection of slope is low. This project constructs cut and fill for
the site gradation, bioretention cell, and driveway. No more than 3’ cut will be expected.
They will have erosion control BMPs installed for slope protection as need. Cut and fill
slopes will be constructed to minimize erosion. During the construction, plastic covering or
other suitable cover material shall be applied to the exposed slopes. Finished slopes shall
have permanent seeding or other vegetation applied. Any stockpiles on site will be located
away from the storm drains inlets and drainage channels. Offsite run-on, if any, will be
diverted away from slopes and disturbed areas with temporary curbs or sand bags.
Will steep slopes be present at the site during construction?
No. the site is realitive flat.
List and describe BMPs: Nets and Blankets, Plastic Covering, seeding.
Installation Schedules: Prior construction and during construction
Inspection and Maintenance plan: Inspect all BMPs at least once a week and replace them as necessary.
Responsible Staff: On site TESC lead.
Page | 12
Element 7: Protect Drain Inlets
Associated construction activities have no risk of potentially affecting water quality in Lake
Stevens. All existing and proposed storm drains within the project site and in the vicinity of the
project site will be protected by using storm drain inlet protection. This BMP is intended to trap
sediment onsite and will be installed and be functional prior to any work or other
land disturbing activities take place.
The inlet protection will be properly maintained to ensure that inlets are functioning correctly.
Inlets should be inspected weekly at the minimum and daily during storm events. Inlet protection
devices should be cleaned or removed and replaced when sediment has filled one-third of the
available storage (unless a different standard is specified by the product manufacturer).
List and describe BMPs: Storm Drain Inlet Protection
Installation Schedules: Prior construction
Inspection and Maintenance plan: Check the Inlet Protection at least once a week, replace it as necessary.
Responsible Staff: On site TESC personnel.
Page | 13
Element 8: Stabilize Channels and Outlets
No existing channels or outlets are located in the project area. Currently, no temporary
conveyance channels are proposed on the TESC Plan Sheets. Since the project limits are
completely flat and no offsite flows are expected into the site, any precipitation that falls on the
site will not leave the construction area. If in situations where stormwater is observed to leave
the site, trenches will be constructed at the perimeter of the project areas to collect the
stormwater before it leaves the construction site. The trenches will then be used to convey (either
by pumping or gravity flow) the stormwater to the portable storage and treatment system for
testing and treatment if necessary prior to discharge to approved discharge location.
Provide stabilization, including armoring material, adequate to prevent erosion of outlets,
adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all
conveyance systems.
List and describe BMPs: N/A
Installation Schedules:
Inspection and Maintenance plan:
Responsible Staff:
Page | 14
Element 9: Control Pollutants
The risk associated with pollutants from construction activities within project area is lowed.
Procedures to prevent and control pollutants and handling of concrete and contaminated material
are described in the Spill Prevention, Control, and Countermeasures (SPCC) Plan and the
Concrete Containment and Disposal Plan (CCDP) prepared by the Contractor.
List and describe BMPs: Dust Control, Concrete Handling, Material Delivery, Storage and Containment
Installation Schedules: Installed prior construction or during construction.
Inspection and Maintenance plan: Check BMPs at least once a week and replace them as necessary.
Responsible Staff: On site TESC lead
Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site?
No
List and describe BMPs: N/A
Installation Schedules:
Inspection and Maintenance plan:
Responsible Staff:
Will wheel wash or tire bath system BMPs be used during construction?
No
List and describe BMPs: N/A
Installation Schedules:
Inspection and Maintenance plan:
Responsible Staff:
Will pH-modifying sources be present on-site?
No
Table 1 – pH-Modifying Sources
X None
Bulk cement
Cement kiln dust
Fly ash
Other cementitious materials
New concrete washing or curing waters
Waste streams generated from concrete grinding and sawing
Exposed aggregate processes
Page | 15
Dewatering concrete vaults
Concrete pumping and mixer washout waters
Recycled concrete
Recycled concrete stockpiles
Other (i.e., calcium lignosulfate) [please describe: ]
List and describe BMPs: N/A
Installation Schedules:
Inspection and Maintenance plan:
Responsible Staff:
Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches,
streets, or streams. Excess concrete must not be dumped on-site, except in designated
concrete washout areas with appropriate BMPs installed.
Will uncontaminated water from water-only based shaft drilling for construction of building, road, and
bridge foundations be infiltrated provided the wastewater is managed in a way that prohibits discharge to
surface waters?
No
List and describe BMPs: N/A
Installation Schedules:N/A
Inspection and Maintenance plan:
Responsible Staff:
Page | 16
Element 10: Control Dewatering
No Dewatering will be taking place for this project. The ground water table is present in the
project area is approximately elevation 5 to 7 feet, it depends on the time of year. The house
footing foundation is 1.5 feet below surface, so no dewatering will be expected for this project.
List and describe BMPs: N/A
Installation Schedules:
Inspection and Maintenance plan:
Responsible Staff:
Page | 17
Element 11: Maintain BMP
The associate risk from sediment entering Lake Washington from the construction site is very
low.
All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained
and repaired as needed to ensure continued performance of their intended function.
Maintenance and repair shall be conducted in accordance with each particular BMP specification
(see Volume II of the SWMMWW or Chapter 7 of the SWMMEW).
Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar
week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the
site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to
once every calendar month.
All temporary ESC BMPs shall be removed within 30 days after final site stabilization is
achieved or after the temporary BMPs are no longer needed.
Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal
of either BMPs or vegetation shall be permanently stabilized.
Additionally, protection must be provided for all BMPs installed for the permanent control of
stormwater from sediment and compaction. BMPs that are to remain in place following
completion of construction shall be examined and restored to full operating condition. If
sediment enters these BMPs during construction, the sediment shall be removed and the facility
shall be returned to conditions specified in the construction documents.
Page | 18
Element 12: Manage the Project
The project will be managed based on the following principles:
• Projects will be phased to the maximum extent practicable and seasonal work limitations
will be taken into account.
• Inspection and monitoring:
o Inspection, maintenance and repair of all BMPs will occur as needed to ensure
performance of their intended function.
o Site inspections and monitoring will be conducted in accordance with Special
Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map.
Sampling station(s) are located in accordance with applicable requirements of the
CSWGP.
• Maintain an updated SWPPP.
o The SWPPP will be updated, maintained, and implemented in accordance with
Special Conditions S3, S4, and S9 of the CSWGP.
As site work progresses the SWPPP will be modified routinely to reflect changing site
conditions. The SWPPP will be reviewed monthly to ensure the content is current.
Table 2 – Management
X Design the project to fit the existing topography, soils, and drainage patterns
X Emphasize erosion control rather than sediment control
X Minimize the extent and duration of the area exposed
X Keep runoff velocities low
X Retain sediment on-site
X Thoroughly monitor site and maintain all ESC measures
X Schedule major earthwork during the dry season
Other (please describe)
Element 13: Protect on-site stormwater management BMPs for runoff
from roofs and other hard surface
Infiltration Trench is proposed BMPs for the roof runff, storm filter catch basin will catch the
driveay runoff from the driveway, then converys to infiltration trench. Protect all BMPs
assicated with bioretention cell during construction activities. Excavate bioretention cell area to
final grade only after all disturbed areas in the updgardient project drainage area have been
permanently stabilized. No excavation of bioretention areas during wet or saturated conditions.
Operate machinery outsid of bioretention cell area during the construction. If BMPs are
impacted during construction, restore them to their original condition or design requirements.
Page | 19
Pollution Prevention Team
Table 3 – Team Information
Title Name(s) Phone Number
Certified Erosion and
Sediment Control Lead
(CESCL)
Jim WU 206-383-8867
Resident Engineer Steve WU 206-795-5674
Emergency Ecology
Contact
Northwest Regional Office 425-649-7000
Emergency Permittee/
Owner Contact
Tran Vu 206-384-3690
Non-Emergency Owner
Contact
Steve WU 206-795-5674
Monitoring Personnel Jim Wu 206-383-8867
Ecology Regional Office Northwest Regional Office 425-649-7000
Page | 20
Monitoring and Sampling Requirements
Monitoring includes visual inspection, sampling for water quality parameters of concern, and
documentation of the inspection and sampling findings in a site log book. A site log book will be
maintained for all on-site construction activities and will include:
•A record of the implementation of the SWPPP and other permit requirements
•Site inspections
•Stormwater sampling data
Create your own Site Inspection Form or use the Construction Stormwater Site Inspection Form
found on Ecology’s website.
http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html
File a blank form under Appendix D.
The site log book must be maintained on-site within reasonable access to the site and be made
available upon request to Ecology or the local jurisdiction.
Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See
CSWGP Special Condition S8 and Section 5 of this template.
Site Inspection
Site inspections will be conducted at least once every calendar week and within 24 hours
following any discharge from the site. For sites that are temporarily stabilized and inactive, the
required frequency is reduced to once per calendar month.
The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with
the applicable requirements of the CSWGP.
Stormwater Quality Sampling
Turbidity Sampling
Requirements include calibrated turbidity meter or transparency tube to sample site discharges
for compliance with the CSWGP. Sampling will be conducted at all discharge points at least
once per calendar week.
Method for sampling turbidity: N/A for this project.
If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to
or greater than 6 cm, the following steps will be conducted:
1.Review the SWPPP for compliance with Special Condition S9. Make appropriate
revisions within 7 days of the date the discharge exceeded the benchmark.
2.Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
Page | 21
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period.
3. Document BMP implementation and maintenance in the site log book.
If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following
steps will be conducted:
1. Telephone or submit an electronic report to the applicable Ecology Region’s
Environmental Report Tracking System (ERTS) within 24 hours.
• Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan,
Yakima): (509) 575-2490 or
http://www.ecy.wa.gov/programs/spills/forms/nerts_online/CRO_nerts_online.html
• Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant,
Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400
or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/ERO_nerts_online.html
• Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish,
Whatcom): (425) 649-7000 or
http://www.ecy.wa.gov/programs/spills/forms/nerts_online/NWRO_nerts_online.html
• Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis,
Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 or
http://www.ecy.wa.gov/programs/spills/forms/nerts_online/SWRO_nerts_online.html
2. Immediately begin the process to fully implement and maintain appropriate source
control and/or treatment BMPs as soon as possible. Address the problems within 10
days of the date the discharge exceeded the benchmark. If installation of necessary
treatment BMPs is not feasible within 10 days, Ecology may approve additional time
when the Permittee requests an extension within the initial 10-day response period
3. Document BMP implementation and maintenance in the site log book.
4. Continue to sample discharges daily until one of the following is true:
• Turbidity is 25 NTU (or lower).
• Transparency is 33 cm (or greater).
• Compliance with the water quality limit for turbidity is achieved.
o 1 - 5 NTU over background turbidity, if background is less than 50 NTU
o 1% - 10% over background turbidity, if background is 50 NTU or greater
• The discharge stops or is eliminated.
Page | 22
pH Sampling
pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards
poured concrete over the life of the project). The use of recycled concrete or engineered soils
(soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln
dust [CKD] or fly ash) also requires pH monitoring.
For significant concrete work, pH sampling will start the first day concrete is poured and
continue until it is cured, typically three (3) weeks after the last pour.
For engineered soils and recycled concrete, pH sampling begins when engineered soils or
recycled concrete are first exposed to precipitation and continues until the area is fully
stabilized.
If the measured pH is 8.5 or greater, the following measures will be taken:
1.Prevent high pH water from entering storm sewer systems or surface water.
2.Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriatetechnology such as carbon dioxide (CO2) sparging (liquid or dry ice).
3.Written approval will be obtained from Ecology prior to the use of chemical treatment
other than CO2 sparging or dry ice.
Method for sampling pH: N/A for this project.
Table 4 – pH Sampling Method
pH meter
pH test kit
X Wide range pH indicator paper
Page | 23
Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies
303(d) Listed Waterbodies
Circle the applicable answer, if necessary:
Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH?
No
TMDL Waterbodies
Waste Load Allocation for CWSGP discharges:
N/A
List and describe BMPs:
Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point
of discharge.
The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water
Body form is included in Appendix F.
Page | 24
Reporting and Record Keeping
Record Keeping
Site Log Book
A site log book will be maintained for all on-site construction activities and will include:
•A record of the implementation of the SWPPP and other permit requirements
•Site inspections
•Sample logs
Records Retention
Records will be retained during the life of the project and for a minimum of three (3) years
following the termination of permit coverage in accordance with Special Condition S5.C of the
CSWGP.
Permit documentation to be retained on-site:
•CSWGP
•Permit Coverage Letter
•SWPPP
•Site Log Book
Permit documentation will be provided within 14 days of receipt of a written request from
Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when
requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP.
Updating the SWPPP
The SWPPP will be modified if:
•Found ineffective in eliminating or significantly minimizing pollutants in stormwater
discharges from the site.
•There is a change in design, construction, operation, or maintenance at the construction
site that has, or could have, a significant effect on the discharge of pollutants to waters
of the State.
The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine
additional or modified BMPs are necessary for compliance. An updated timeline for BMP
implementation will be prepared.
Page | 25
Reporting
Discharge Monitoring Reports
Cumulative soil disturbance is less than one (1) acre; therefore, Discharge Monitoring
Reports (DMRs) will not be submitted to Ecology because water quality sampling is not being
conducted at the site.
Notification of Noncompliance
If any of the terms and conditions of the permit is not met, and the resulting noncompliance may
cause a threat to human health or the environment, the following actions will be taken:
1.Ecology will be notified within 24-hours of the failure to comply by calling the applicable
Regional office ERTS phone number (Regional office numbers listed below).
2.Immediate action will be taken to prevent the discharge/pollution or otherwise stop or
correct the noncompliance. If applicable, sampling and analysis of any noncompliance
will be repeated immediately and the results submitted to Ecology within five (5) days of
becoming aware of the violation.
3.A detailed written report describing the noncompliance will be submitted to Ecology
within five (5) days, unless requested earlier by Ecology.
Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6
cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as
required by Special Condition S5.A of the CSWGP.
•Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit,
Snohomish, or Whatcom County
Include the following information:
1.Your name and / Phone number
2.Permit number
3.City / County of project
4.Sample results
5.Date / Time of call
6.Date / Time of sample
7.Project name
In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will
be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH
water.
Page | 26
Appendix/Glossary
A. Site Map
The site map must meet the requirements of Special Condition S9.E of the CSWGP
B. BMP Detail
Insert BMPs specification sheets here.
Download BMPs from the Ecology Construction Stormwater website at:
http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html
Select Resources and Guidance to find the links to the Stormwater Manuals.
C. Site Inspection Form
Create your own or download Ecology’s template:
http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html
Select Permit, Forms and Application to find the link to the Construction Stormwater
Site Inspection Form.
Type text here
Q (cfs) Acre Square Area (S.F.)
0.143 0.42 297.9166667
See MDF for 2 ‐year storm event using 15‐minutes time steps
Assumed: site will disturb 0.4 acres soil
Note
See WSDOT Temporary Erosion and Sediment Control Manual M3109.02
Charter 5,From Page 5‐44 to Page 5‐46
—————————————————————————————————
MGS FLOOD
PROJECT REPORT
Program Version: MGSFlood 4.52
Program License Number: 200210003
Project Simulation Performed on: 05/05/2022 11:55 AM
Report Generation Date: 05/05/2022 11:56 AM
—————————————————————————————————
Input File Name: Sediment trap.fld
Project Name: Aberdeen
Analysis Title: Sediment Trap
Comments:
———————————————— PRECIPITATION INPUT ————————————————
Computational Time Step (Minutes): 15
Extended Precipitation Time Series Selected
Climatic Region Number: 32
Full Period of Record Available used for Routing
Precipitation Station : 99003805 Seattle 38 in_5min 10/01/1939-10/01/2097
Evaporation Station : 991038 Seattle 38 in MAP
Evaporation Scale Factor : 0.750
HSPF Parameter Region Number: 1
HSPF Parameter Region Name : USGS Default
********** Default HSPF Parameters Used (Not Modified by User) ***************
********************** WATERSHED DEFINITION ***********************
Predevelopment/Post Development Tributary Area Summary
Predeveloped Post Developed
Total Subbasin Area (acres) 0.420 0.420
Area of Links that Include Precip/Evap (acres) 0.000 0.000
Total (acres) 0.420 0.420
----------------------SCENARIO: PREDEVELOPED
Number of Subbasins: 1
---------- Subbasin : Subbasin 1 ----------
-------Area (Acres) --------
Till Grass 0.420
----------------------------------------------
Subbasin Total 0.420
----------------------SCENARIO: POSTDEVELOPED
Number of Subbasins: 1
---------- Subbasin : Subbasin 1 ----------
-------Area (Acres) --------
Impervious 0.420
----------------------------------------------
Subbasin Total 0.420
************************* LINK DATA *******************************
----------------------SCENARIO: PREDEVELOPED
Number of Links: 0
************************* LINK DATA *******************************
----------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
------------------------------------------
Link Name: Sediment Trap
Link Type: Structure
Downstream Link: None
Prismatic Pond Option Used
Pond Floor Elevation (ft) : 100.00
Riser Crest Elevation (ft) : 103.00
Max Pond Elevation (ft) : 104.00
Storage Depth (ft) : 3.00
Pond Bottom Length (ft) : 100.0
Pond Bottom Width (ft) : 50.0
Pond Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00
Bottom Area (sq-ft) : 5000.
Area at Riser Crest El (sq-ft) : 8,024.
(acres) : 0.184
Volume at Riser Crest (cu-ft) : 19,374.
(ac-ft) : 0.445
Area at Max Elevation (sq-ft) : 9176.
(acres) : 0.211
Vol at Max Elevation (cu-ft) : 27,968.
(ac-ft) : 0.642
Hydraulic Conductivity (in/hr) : 0.00
Massmann Regression Used to Estimate Hydralic Gradient
Depth to Water Table (ft) : 100.00
Bio-Fouling Potential : Low
Maintenance : Average or Better
Riser Geometry
Riser Structure Type : Circular
Riser Diameter (in) : 24.00
Common Length (ft) : 0.000
Riser Crest Elevation : 103.00 ft
Hydraulic Structure Geometry
Number of Devices: 1
---Device Number 1 ---
Device Type : Circular Orifice
Control Elevation (ft) : 100.00
Diameter (in) : 1.00
Orientation : Horizontal
Elbow : Yes
**********************FLOOD FREQUENCY AND DURATION STATISTICS*******************
----------------------SCENARIO: PREDEVELOPED
Number of Subbasins: 1
Number of Links: 0
----------------------SCENARIO: POSTDEVELOPED
Number of Subbasins: 1
Number of Links: 1
***********Groundwater Recharge Summary *************
Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures
Total Predeveloped Recharge During Simulation
Model Element Recharge Amount (ac-ft)
-----------------------------------------------------------------------------------------------
Subbasin: Subbasin 1 48.925
_____________________________________
Total: 48.925
Total Post Developed Recharge During Simulation
Model Element Recharge Amount (ac-ft)
-----------------------------------------------------------------------------------------------
Subbasin: Subbasin 1 0.000
Link: Sediment Trap Not Computed
_____________________________________
Total: 0.000
Total Predevelopment Recharge is Greater than Post Developed
Average Recharge Per Year, (Number of Years= 158)
Predeveloped: 0.310 ac-ft/year, Post Developed: 0.000 ac-ft/year
***********Water Quality Facility Data *************
----------------------SCENARIO: PREDEVELOPED
Number of Links: 0
----------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
***********Compliance Point Results *************
Scenario Predeveloped Compliance Subbasin: Subbasin 1
Scenario Postdeveloped Compliance Subbasin: Subbasin 1
*** Point of Compliance Flow Frequency Data ***
Recurrence Interval Computed Using Gringorten Plotting Position
Predevelopment Runoff Postdevelopment Runoff
Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs)
----------------------------------------------------------------------------------------------------------------------
2-Year 2.939E-02 2-Year 0.143
5-Year 6.576E-02 5-Year 0.208
10-Year 9.457E-02 10-Year 0.242
25-Year 0.114 25-Year 0.294
50-Year 0.130 50-Year 0.316
100-Year 0.144 100-Year 0.335
200-Year 0.172 200-Year 0.380
500-Year 0.210 500-Year 0.440
** Record too Short to Compute Peak Discharge for These Recurrence Intervals
**** Flow Duration Performance ****
Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): 2137.7% FAIL
Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%): 11884.6% FAIL
Maximum Excursion from Q2 to Q50 (Must be less than 10%): 99999.0% FAIL
Percent Excursion from Q2 to Q50 (Must be less than 50%): 100.0% FAIL
-------------------------------------------------------------------------------------------------
FLOW DURATION DESIGN CRITERIA: FAIL
-------------------------------------------------------------------------------------------------
**** LID Duration Performance ****
Excursion at Predeveloped 8%Q2 (Must be Less Than 0%): 21.8% FAIL
Maximum Excursion from 8%Q2 to 50%Q2 (Must be Less Than 0%): 2137.7% FAIL
-------------------------------------------------------------------------------------------------
LID DURATION DESIGN CRITERIA: FAIL
-------------------------------------------------------------------------------------------------
TESC Best Management Practices Chapter 5
Page 5-44 WSDOT Temporary Erosion and Sediment Control Manual M 3109.02
May 2019
Additional Information
Managing a large construction project with multiple contractors is a major
coordination challenge. Weekly meetings, progress reports and schedules, or
other methods of consistent communication are vital. Developing and following
a specified work schedule that coordinates the timing of land-disturbing activity
with the installation of appropriate BMPs requires effective communication
between environmental site inspectors, CESCLs, contractors, subcontractors,
and the Project Engineer.
Construction practices that limit or phase land-clearing activity and provide timely
installation of erosion and sediment control BMPs can significantly reduce potential
environmental impacts. Sediment control (treatment) BMPs must be installed to
protect potential discharge points prior to land-disturbing activity in an area.
Whenever feasible:
Minimize grading or excavation work during the rainy season.
Phase work to minimize the total area of exposed soil at any one time.
Install sedimentation ponds or detention facilities, stabilized construction,
and sediment control BMPs prior to work in an area.
Practice staged seeding in order to revegetate areas as soon as possible.
5-1.1.30 Sediment Traps
No Standard Specification
Standard Plan
I-80.10 – Miscellaneous Erosion Control Details
SWMM Volume II equivalent: BMP C240 Sediment Trap
Function
Sediment traps are used to aid in the settling of suspended sediments from
concentrated flows.
Chapter 5 TESC Best Management Practices
WSDOT Temporary Erosion and Sediment Control Manual M 3109.02
May 2019
Page 5-45
Additional Information
Intended for use on sites where the tributary drainage area is less than
3 acres, with no unusual drainage features and with a projected build-
out time of 6 months or less. If the tributary drainage area is more than 3
acres, use a temporary sediment pond.
Trap efficiency is enhanced when runoff is passed through multiple sediment
control BMPs.
Sediment traps are limited to removing silt/larger-sized sediment particles.
Trap effectiveness increases with trap size.
Design, Installation and Maintenance
1.Sizing Procedure
To determine the sediment trap geometry, first calculate the design surface
area (SA) of the trap, measured at the invert of the weir. Use the following
equation:
SA = FS(Q/Vs)
where: Q = Design inflow based on criteria below.
Vs = The settling velocity of the soil particle of
interest. The 0.02 mm (medium silt) particle
with an assumed density of 2.65 g/cm3 has
been selected as the particle of interest and
has a settling velocity (Vs) of 0.00096 ft/sec.
FS = A safety factor of 2 to account for non-ideal
settling.
Therefore, the equation for computing surface area becomes:
SA = 2 x Q/0.00096 or
2,080 square feet per cfs of inflow
Note: Even if permanent facilities are used, they must still have
a surface area that is at least as large as that derived from the
above formula. If they do not, the pond must be enlarged.
TESC Best Management Practices Chapter 5
Page 5-46 WSDOT Temporary Erosion and Sediment Control Manual M 3109.02
May 2019
Design Q for sizing:
Eastern Washington should be designed to handle the 2-year peak
flow rate from the appropriate long duration storm event using a
single event model. See HRM Appendix 4C to determine the Climatic
Region and appropriate long duration storm event for the project.
The designer should consult with Region Hydraulics staff to determine
whether a higher level of protection is needed beyond the 2-year
peak flow due to the time of year for construction (freezing
conditions and snowmelt), the downstream conditions, or the
expectation that the project will last several construction seasons.
Western Washington should be designed to handle peak flows
generated by the 2-year storm event using 15-minute time steps
predicted by MGSFlood for the developed site condition without flow
control. The designer should consult Region Hydraulics staff to
determine if downstream conditions warrant a higher level of
protection. The 10-year peak flow using 15-minute time steps should
be used if the project is expected to last several construction seasons.
Note that sediment traps may not be feasible on utility projects due to the
limited work space or the short-term nature of the work. Use portable tanks
in place of sediment traps for utility projects.
Remove sediment from the trap when it reaches 1 foot in depth.
Repair any damage to the pond embankments or slopes.
5-1.1.31 Sedimentation Bags
No Standard Specification or Standard Plan
No SWMM Volume II equivalent
Function
Sedimentation bags are considered pre-treatment BMPs because they work to
remove coarse sediment from turbid water before it receives additional treatment.
Additional Information
Sedimentation or filtration dewatering bags are a pretreatment BMP, meaning the
water that filters through the bag must receive additional treatment prior to
discharging to surface waters.
Base the selection of the bag product on pump flow rate, the amount and type of
suspended sediment in the water, and permittivity of the bag. As the bag fills with
sediment, take measures to prevent bag failure or bursting (e.g., reduce pump flow
APPENDIX G
Drainage Basin Surface areas
Geotechnical Report
NELSON GEOTECHNICAL ASSOCIATES, INC.
February 26, 2021
Mr. Long Nguyen
11904 SE 228th Place
Kent, Washington 98051
VIA Email:longdnguyen@gmail.com
Geotechnical Engineering Evaluation
Nguyen Aberdeen Avenue NE Short Plat Residential Development
2309 Aberdeen Avenue NE
Renton, Washington
NGA File No. 1227220
Dear Mr. Nguyen:
We are pleased to submit the attached report titled “Geotechnical Engineering Evaluation – Nguyen
Aberdeen Avenue NE Short Plat Residential Development – 2309 Aberdeen Avenue NE – 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 issued to you on January21, 2021.
The property is currently vacant but was previously occupied with an existing single-family residence
within the western portion of the property. The ground surface within the property is relatively level to
gently sloping down from the west to the east. We understand that the proposed development will
include construction of three new single-family residences and associated roadways and underground
utilities.
We explored the subsurface conditions within the site with eleven trackhoe excavated test pits
explorations. The explorations extended to depths in the range of 5.5 to 11.5 feet below the existing
ground surface. Our explorations indicated that the site was underlain by surficial undocumented fill
soils with competent native glacial outwash soils at depth.
It is our opinion that the proposed site development is feasible from a geotechnical engineering
standpoint, provided that our recommendations for site development are incorporated into project
plans. In general, the native glacial bearing soils underlying the site should adequately support the
planned structures. Foundations should be advanced through any loose and/or undocumented fill soils
down to the competent glacial bearing material interpreted to underlie the site, for bearing capacity and
settlement considerations. These soils should generally be encountered between approximately 2.0 to
6.0 feet below the existing ground surface, based on our explorations. The deepest areas of
undocumented fill were generally encountered within the lower very eastern portion of the property. If
deeper areas of loose soils or undocumented fill are encountered in unexplored areas of the site, they
should be removed and replaced with structural fill for foundation and pavement support.
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Specific grading and stormwater plans have not been finalized at the time this report was prepared.
However, we understand that stormwater from the proposed development may be directed into on-site
infiltration systems, if feasible. The City of Renton uses the 2016 King County Surface Water Design
Manual, as amended by the City of Renton Storm Water Manual to determine the design of infiltration
facilities. According to this manual and the City of Renton requirements, on-site infiltration testing
consisting of the small Pilot Infiltration Test (PIT) is used to determine the long-term design infiltration
rates. Based on the results of our on-site infiltration testing and granular nature of the native glacial
outwash soils encountered within the western and central portion of the site, it is our opinion that the
onsite native outwash soils within the western and central portion of the property are conducive for
traditional stormwater infiltration methods. However, it is our opinion that stormwater infiltration is
not feasible within the very eastern portion of the property due to the overall depth of the
undocumented fill and presence of perched groundwater encountered at depth within our eastern
explorations. This is discussed in more detail in the attached report.
In the attached report, we have also provided general recommendations for site grading, slabs-on-
grade, structural fill placement, retaining walls, erosion control, and drainage. We should be retained to
review and comment on final development plans and observe the earthwork phase of construction. We
also 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
construction differ from those anticipated, and to evaluate whether or not earthwork and foundation
installation activities comply with contract plans and specifications.
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 further information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Khaled M. Shawish, PE
Principal Engineer
TABLE OF CONTENTS
INTRODUCTION .......................................................................................................... 1
SCOPE.........................................................................................................................1
SITE CONDITIONS........................................................................................................2
Surface Conditions........................................................................................................2
Subsurface Conditions..................................................................................................2
Hydrogeologic Conditions............................................................................................. 3
SENSITIVE AREA EVALUATION ..................................................................................... 4
Seismic Hazard .............................................................................................................. 4
Erosion Hazard .............................................................................................................. 4
CONCLUSIONS AND RECOMMENDATIONS .................................................................. 5
General ......................................................................................................................... 5
Erosion Control ............................................................................................................. 6
Site Preparation and Grading ....................................................................................... 6
Temporary and Permanent Slopes ............................................................................... 7
Foundations .................................................................................................................. 8
Retaining Walls ............................................................................................................. 9
Structural Fill ............................................................................................................... 10
Slab-on-Grade ............................................................................................................. 11
Pavements .................................................................................................................. 11
Utilities ........................................................................................................................ 11
Site Drainage ............................................................................................................... 12
CONSTRUCTION MONITORING .................................................................................. 14
USE OF THIS REPORT ................................................................................................. 14
LIST OF FIGURES
Figure 1 – Vicinity Map
Figure 2 – Site Plan
Figure 3 – Soil Classification Chart
Figures 4 through 6 – Exploration Logs
Geotechnical Engineering Evaluation
Nguyen Aberdeen Avenue NE Short Plat Residential Development
2309 Aberdeen Avenue NE
Renton, Washington
INTRODUCTION
This report presents the results of our geotechnical engineering investigation and evaluation of the planned
residential development project in Renton, Washington. The project site is located at 2309 Aberdeen
Avenue NE, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and
characterize the site’s surface and subsurface conditions and to provide geotechnical recommendations for
the planned site development.
The property is currently vacant but was previously occupied with an existing single-family residence within
the western portion of the property. The ground surface within the property is relatively level to gently
sloping down from the west to the east. We understand that the proposed development will include
construction of three new single-family residences and associated roadways and underground utilities.
Final development and grading plans have not been prepared at the time this report was issued. Final
stormwater plans have also not been developed, however, we understand that stormwater may be
directed to on-site infiltration systems, if feasible. The existing site layout is 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.
Specifically, our scope of services included the following:
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. Perform grain-size sieve analysis on soil samples, as necessary.
4. Provide recommendations for structure foundations.
5. Provide recommendations for earthwork.
6. Provide recommendations for temporary and permanent slopes.
7. Provide recommendations for retaining walls.
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8. Provide recommendations for slab and pavement subgrade preparation.
9. Provide recommendations for utility installation.
10. Provide long-term design infiltration rates based on on-site Pilot Infiltration Testing (PIT)
per the 2016 King County Surface Water Design Manual. Location and depth of tests were
determined by the civil engineer. Water for the tests was secured by client.
11. Provide recommendations for infiltration system installation.
12. Provide recommendations for site drainage and erosion control.
13. Document the results of our findings, conclusions, and recommendations in a written
geotechnical report.
SITE CONDITIONS
Surface Condition
The site consists of a roughly square-shaped parcel covering approximately 0.84 acres. The site is currently
vacant but was previously occupied by a single-family residence within the western portion of the site.
Topography within the western and central portion of the slopes gently down from the western property
line to the eastern portion of the property. The eastern portion of the property is generally level. The site
is generally vegetated by grass-covered yard areas, young to mature trees, and landscaping. A horseshoe-
shaped gravel driveway is located within the eastern portion of the property. The property is bound to the
north, south, and west by single-family residences, and to the east by Aberdeen Avenue NE. We did not
observe surface water within the site during our site visit on February 5, 2021.
Subsurface Conditions
Geology: The geologic units for this site are shown on Preliminary Geologic Map of Seattle and Vicinity,
Washington, by Waldron, H.H., Leisch, B.A., Mullineaux, D.R., and Crandell, D.R., (USGS, 1961). The site is mapped as
younger gravel (Qyg) with younger sand (Qys) and alluvium (Qa) mapped nearby. The younger gravel and
sand deposits are described as fine to coarse sand that contains varying amounts of gravel. The alluvium is
described as silt with varying amounts of sand and organic material. Our explorations generally
encountered fine to coarse sand with varying amounts of gravel and silt within the western and central
portion of the property that we interpreted as younger gravel outwash soils. Our explorations within the
very eastern portion of the property generally encountered silt with sand and silty fine to medium sand
that we interpreted as native alluvium and younger sand deposits at depth.
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Explorations: The subsurface conditions within the site were explored on February 5, 2021 by excavating
eleven test pits with a mini-trackhoe extending to depths in the range of 5.5 to 11.5 feet below the existing
ground surface. The approximate locations of our explorations are shown on the 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.
The soils were visually classified in general accordance with the Unified Soil Classification System, presented
in Figure 3. The logs of our explorations are attached to this report and are presented as Figures 4 through
6. We present a brief summary of the subsurface conditions in the following paragraph. For a detailed
description of the subsurface conditions, the logs of the explorations should be reviewed.
At the surface of all of our explorations, we encountered approximately 0.5 to 6.0 feet of surficial grass and
loose to medium dense dark brown silty fine to medium sand with varying amounts of gravel, organics and
debris that we interpreted as surficial topsoil and/or undocumented fill soils. Underlying the surficial
topsoil/undocumented fill soils within Test Pit 1, 2, 8, and 9 within the eastern portion of the site, we
encountered medium dense/stiff orange-brown to gray-brown silty fine to medium sand and silt with fine
sand with varying amounts of gravel and organics that we interpreted as younger sand and alluvium
deposits, respectively. Below the surficial topsoil and/or the undocumented fill in Test Pits 3 through 7, 10,
and Infiltration Pit 1, we encountered medium dense to dense fine to coarse sand with varying amounts of
silt and gravel that we interpreted as native younger gravel soils. All of our test pits were terminated within
the native younger gravel and sand soils at depths in the range of 5.5 to 11.5 feet below the existing ground
surface.
Hydrogeologic Conditions
We encountered minor to moderate groundwater seepage within Test Pits 1 and 8 at a depth of 8.0 feet
below the existing ground surface. We interpreted this groundwater seepage to be perched groundwater.
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.
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SENSITIVE AREA EVALUATION
Seismic Hazard
We reviewed the 2018 International Building Code (IBC) for seismic site classification for this project.
Since competent glacial soils are inferred to underlie the site at depth, the site conditions best fit the IBC
description for Site Class D.
Table 1 below provides seismic design parameters for the site that are in conformance with the 2018
IBC, which specifies a design earthquake having a two percent probability of occurrence in 50 years
(return interval of 2,475 years), and the 2008 USGS seismic hazard maps.
Table 1 – 2018 IBC Seismic Design Parameters
Site Class Spectral Acceleration
at 0.2 sec. (g)
Ss
Spectral Acceleration
at 1.0 sec. (g)
S1
Site Coefficients Design Spectral
Response
Parameters
Fa Fv SDS SD1
D 1.473 0.542 1.000 1.500 0.958 0.542
The spectral response accelerations were obtained from the USGS Earthquake Hazards Program
Interpolated Probabilistic Ground Motion website (2008 data) for the project latitude and longitude.
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 medium dense or better glacial outwash deposits interpreted to underlie
the site and nearby vicinity 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 Natural Resources Conservation Service (NRCS), was
reviewed to determine the erosion hazard of the on-site soils. The surface soils for this site were mapped
as Indianola loamy sand, 5 to 15 percent slopes. The erosion hazard for this material is listed as slight. This
site is relatively level to gently sloping and there are no steep slopes on the property. It is our opinion that
the erosion hazard for site soils should be low in areas where the site is not disturbed.
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CONCLUSIONS AND RECOMMENDATIONS
General
It is our opinion that the planned development within the site is generally feasible from a geotechnical
standpoint. Our explorations indicated that the site is generally underlain by competent native glacial till
soils at depth throughout the site. The native glacial bearing soils encountered at depth should provide
adequate support for foundation, slab, and pavement loads. We recommend that the planned structure be
designed utilizing conventional shallow foundations. Footings should extend through any loose soil or
undocumented fill soils and be founded on the underlying medium dense or better native glacial till soils, or
structural fill extending to these soils.
The medium dense or better native glacial bearing soils should typically be encountered approximately 2.0
to 6.0 feet below the existing surface, based on our explorations. In general, the competent native glacial
soils were shallower within the western portion of the site and were deepest within the very eastern
portion of the site. 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.
Based on the results of our on-site infiltration testing and soil explorations throughout the site, it is our
opinion that the onsite native granular outwash soils encountered within the western and central portion
of the site are conducive for full stormwater infiltration methods. However, due to the deeper
undocumented fill soils and presence of perched groundwater within our very eastern explorations, it is our
opinion that stormwater infiltration is not feasible within the very eastern portion of the property. This is
further discussed in the Site Drainage section of this report.
The surficial soils encountered on this site are considered moisture-sensitive and will 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. NGA should be retained to determine if the on-site soils can be used as structural fill material
during construction.
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Erosion Control
The erosion hazard for the on-site soils is interpreted to be slight to moderate 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 diverting 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,
undocumented fill and loose soils from foundation, slab, pavement areas, and other structural areas, to
expose medium dense or better native bearing glacial 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 2.0 to 6.0 feet, depending on the specific locations. In general, the competent native glacial soils
were shallower within the western portion of the property and deeper within the eastern portion of the
property. However, additional stripping may be required if areas of deeper undocumented fill and/or loose
soil are encountered in unexplored areas of the site.
After site stripping, if the exposed subgrade is deemed 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
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disturbance by machine or foot traffic during construction. The prepared subgrade should be protected
from construction traffic and surface water should be diverted around areas of prepared subgrade.
The site soils are considered to be moisture-sensitive and will disturb easily 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
native 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.
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/surficial soils
be no steeper than 2 Horizontal to 1 Vertical (2H:1V). Temporary cuts in the competent native glacial
outwash soils at depth should be no steeper than 1.5H: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.
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Permanent cut and fill slopes should be no steeper than 2H:1V. 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 glacial
outwash soils or be supported on structural fill or rock spalls extending to those soils. Native medium
dense or better glacial bearing soils should be encountered approximately 2.0 to 6.0 feet below the existing
ground surface based on our explorations. We typically encountered deeper areas of surficial
undocumented fill soils within our explorations within the eastern portion of the site, and shallower
undocumented fill soils within the western portion of the site.
Where undocumented fill or less dense soils are encountered at footing bearing elevation, the subgrade
should be over-excavated to expose native bearing soil. The over-excavation may be filled with structural
fill, or the footings 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 half of the
depth of the over-excavation below the bottom of the footing. In case of excessive undocumented fill
thickness, deep foundation options may be required. NGA is available to work with the structural engineer
to explore those options.
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
2018 IBC. 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 prior to placing concrete.
For foundations constructed as outlined above, we recommend an allowable 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 bearing material. The foundation
bearing soil should be evaluated by a representative of NGA. We should be consulted if higher bearing
pressures are needed. Current IBC guidelines should be used when considering increased allowable bearing
pressure for short-term transitory wind or seismic loads. Potential foundation settlement using the
recommended allowable bearing pressure is estimated to be less than 1-inch total and ½-inch differential
between adjacent footings or across a distance of about 20 feet, based on our experience with similar
projects.
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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
(pcf) 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 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.
A seismic design loading of 8H should also be included in the wall design, where “H” represents the total
height of the wall.
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 height of the wall,
and do not account for surcharge loads. Additional lateral earth pressures should be considered for
surcharge loads acting adjacent to walls and within a distance equal to the 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.
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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.
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 native on-site soils may be suitable for use as structural
fill, but this will be highly dependent on the moisture content of these soils at the time of 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.
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Maximum dry density, in this report, 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 and
should be tested.
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. 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 barrier. 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 stable subgrade. 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 six 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 percent of the modified proctor as described in the Structural Fill subsection of this
report. Trench backfill should be compacted to a minimum of 95 percent of the modified proctor maximum
dry density. Trenches located in non-structural areas and five feet below roadway subgrade should be
compacted to a minimum 90 percent of the maximum dry density. The trench backfill compaction should
be tested.
Geotechnical Engineering Evaluation NGA File No. 1227220
Nguyen Aberdeen Avenue NE Short Plat Residential Development February 26, 2021
Renton, Washington Page 12
NELSON GEOTECHNICAL ASSOCIATES, INC.
Site Drainage
Infiltration: The subsurface soils within our explorations at depth generally consisted of granular glacial
outwash soils to the depths explored within the western and central portion of the site and native alluvial
soils within the very eastern portion of the property. In accordance with the 2016 King County Surface
Water Design Manual (KCSWDM), we conducted one Small PIT within Infiltration Pit 1 within the central
portion of the property as shown on the attached Site Plan in Figure 2. Infiltration Pit 1 measured 4.0-feet
long by 3.0-feet wide by 8.0-feet deep. Due to the granular nature of the site soils and the maximum
capacity of the on-site water source, we were only able to maintain approximately 2.0-inches of standing
water within Infiltration Pit 1 instead of the recommended 12-inches. This level was maintained for
approximately 6 hours for the pre soak period of the test.
After the 6-hour soaking period was completed, the water level was maintained at approximately 2-inches
for one hour for the steady-state period with the maximum flow rate of the on-site water source. At this
time, the water flow rate into the hole was monitored with a Great Plains Industries (GPI) TM 050 water
flow meter. The maximum flow rate of the on-site water source for Infiltration Pit 1 stabilized at 6.67
gallons per minute (400.2 gallons per hour), which equates to an approximate infiltration rate of 53.50
inches per hour. The water was shut off after the steady-state period of the test and was monitored for the
falling head portion of the test. After 2 minutes, the water level within the pit had fully infiltrated resulting
in an infiltration rate of 60.0 inches per hour.
It is our opinion that the native granular outwash soils encountered at depth within the western and central
portion of the property are suitable for traditional stormwater infiltration. The subsurface soils within the
western and central portion of the property generally consisted of granular outwash sand soils at depth.
We have selected the most conservative measured field rate of 53.5 in/hr obtained from the falling head
portions of the test in our infiltration pit to be utilized in determining the long-term design infiltration rate
for the infiltration systems within the western and central portions of the property. We referenced
Equation 5-11 within Chapter 5.2.1 of the (KCSWDM) that applies correction factors to the field measured
infiltration rate to generate a long-term design infiltration rate. Correction factors of 0.50, 0.90, and 0.80
were utilized in this equation for Ftesting, Fgeometry, Fplugging respectively, resulting in an infiltration rate of 19.25
inches per hour, to be utilized to design any on-site infiltration systems founded within the native granular
outwash soils within the western and central portions of the property. We recommend that the base of the
infiltration systems within the western and central portions of the property be terminated within the native
granular outwash soils encountered at approximately 0.5 to 6.0 feet below the existing ground surface
within the western and central portions of the property. We recommend that stormwater infiltration
systems not be located within the eastern portion of the property due to the presence of surficial
Geotechnical Engineering Evaluation NGA File No. 1227220
Nguyen Aberdeen Avenue NE Short Plat Residential Development February 26, 2021
Renton, Washington Page 13
NELSON GEOTECHNICAL ASSOCIATES, INC.
undocumented fill and perched groundwater encountered at depth within our explorations within the very
eastern portion of the property. NGA should be retained to observe infiltration trench excavations.
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 groundwater
seepage within our test pit explorations within the western and central portion of the site to a depth of
approximately 11.5 feet below the existing ground surface. We recommend that the base of any proposed
infiltration systems be located to maintain minimum separation from any groundwater and impermeable
horizons in accordance with the stormwater manual and the City of Renton requirements. We also
recommend that any proposed infiltration systems be placed 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 as discussed in the drainage manual. Infiltration systems should not be located within
proposed fill areas within the site associated with site grading or retaining wall backfill as such condition
could lead to failures of the placed fills and/or retaining structures. We recommend that the base of the
on-site infiltration systems be extended through the upper undocumented fill and surficial soils and
terminated within the native glacial outwash soils encountered at depth throughout the site. We should be
retained during construction to evaluate the soils exposed in the infiltration systems to verify that the soils
are appropriate for infiltration.
Surface Drainage: The finished ground surface should be graded such that stormwater is directed to an
approved 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 downward 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 approved discharge system.
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.
Geotechnical Engineering Evaluation NGA File No. 1227220
Nguyen Aberdeen Avenue NE Short Plat Residential Development February 26, 2021
Renton, Washington Page 14
NELSON GEOTECHNICAL ASSOCIATES, INC.
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 tightlines
leading to an approved 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 Mr. Long Nguyen 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 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.
o-o-o
Geotechnical Engineering Evaluation NGA File No. 1227220
Nguyen Aberdeen Avenue NE Short Plat Residential Development February 26, 2021
Renton, Washington Page 15
NELSON GEOTECHNICAL ASSOCIATES, INC.
It has been a pleasure to provide service to you on this project. If you have any questions or require further
information, please call.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Lee S. Bellah, LG
Project Geologist
Khaled M. Shawish, PE
Principal
LSB:KMS:dy
Six Figures Attached
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
DJO:DPN NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 1227220
FIGURE 4
INFILTRATION PIT ONE
0.0 – 3.5 GRASS UNDERLAIN BY LIGHT BROWN TO DARK BROWN, SILTY FINE TO MEDIUM SAND WITH
GRAVEL, COBBLES, IRON OXIDE WEATHERING, ORGANICS, AND ROOTS
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
3.5 – 5.5 ORANGE-BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH ROOTS, IRON OXIDE
WEATHERING, GRAVEL, COBBLES, AND TRACE ORGANICS (MEDIUM DENSE, MOIST) (FILL)
5.5 – 10.0 SP-SM GRAY-BROWN TO GRAY, FINE TO COARSE SAND WITH GRAVEL, COBBLES, SILT, ROOTS,
AND IRON OXIDE WEATHERING (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE NOT COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 10.0 FEET ON 2/5/21
TEST PIT ONE
0.0 – 3.0 GRASS UNDERLAIN BY BROWN TO LIGHT BROWN, SILTY FINE TO MEDIUM SAND WITH
GRAVEL, ROOTS, AND ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
3.0 – 5.0 DARK BROWN TO BLACK, SILTY FINE TO MEDIUM SAND WITH GRAVEL, TRACE ROOTS, AND
ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
5.0 – 8.0 ML GRAY TO GRAY-BROWN, SILT WITH FINE SAND, ORGANIC PARTICULATE, IRON OXIDE
STAINING (STIFF TO VERY STIFF, MOIST)
8.0 – 10.0 SP-SM GRAY TO GRAY-BROWN, FINE TO MEDIUM SAND WITH SILT
(MEDIUM DENSE TO DENSE, MOIST TO WET)
SAMPLES WERE COLLECTED AT 5.5 AND 8.5 FEET
GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 8.0
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 10.0 FEET ON 2/5/21
TEST PIT TWO
0.0 – 3.0 GRASS UNDERLAIN BY BROWN, SILTY FINE TO MEDIUM SAND WITH ROOTS, ORGANICS,
AND GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
3.0 – 5.0 DARK BROWN TO BLACK, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS, ORGANICS,
ASPHALT CHUNKS AND TRACE COBBLES (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
5.0 – 10.0 SM ORANGE-BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL
(MEDIUM DENSE, MOIST)
SAMPLES WERE NOT COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 10.0 FEET ON 2/5/21
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
DJO:DPN NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 1227220
FIGURE 5
TEST PIT THREE
0.0 – 0.5 GRASS UNDERLAIN BY SILTY, FINE TO MEDIUM SAND WITH ROOTS, ORGANICS, AND
GRAVEL (LOOST TO MEDIUM DENSE, MOIST) (FILL)
0.5 – 1.5 SM GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND IRON OXIDE STAINING
(MEDIUM DENSE, MOIST)
1.5 – 10.5 SP BROWN-GRAY FINE TO COARSE SAND WITH GRAVEL AND TRACE SILT
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED AT 3.0, 6.0, AND 9.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
SLIGHT TEST PIT CAVING WAS ENCOUNTERED BETWEEN 4.0 AND 10.0 FEET
TEST PIT WAS COMPLETED AT 10.5 FEET ON 2/5/21
TEST PIT FOUR
0.0 – 0.5 GRASS UNDERLAIN BY DARK BROWN SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS,
AND ORGANICS (LOOST TO MEDIUM DENSE, MOIST) (FILL)
0.5 – 3.0 SM BROWN-GRAY, SILTY FINE TO MEDIUM SAND WITH GRAVEL (MEDIUM DENSE, MOIST)
3.0 – 10.0 SP BROWN-GRAY, FINE TO COARSE SAND WITH GRAVEL AND TRACE SILT
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED AT 5.0 AND 9.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS ENCOUNTERED BETWEEN 5.0 AND 10.0 FEET
TEST PIT WAS COMPLETED AT 10.0 FEET ON 2/5/21
TEST PIT FIVE
0.0 – 1.5 GRASS UNDERLAIN BY DARK BROWN TO ORANGE BROWN, SILTY FINE TO COARSE SAND
WITH GRAVEL, TRACE COBBLES, AND IRON OXIDE WEATHERING
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
1.5 – 11.0 SP GRAY TO ORANGE-GRAY, FINE TO COARSE SAND WITH GRAVEL, ROOTS, IRON-OXIDE
WEATHERING, COBBLES, AND TRACE SILT (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED AT 5.0 AND 9.0 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
SLIGHT TEST PIT CAVING WAS ENCOUNTERED AT 1.5 FEET
TEST PIT WAS COMPLETED AT 11.0 FEET ON 2/5/21
TEST PIT SIX
0.0 – 1.0 GRASS UNDERLAIN BY DARK BROWN TO ORANGE-BROWN, SILTY FINE TO COARSE SAND
WITH GRAVEL, TRACE COBBLES, AND IRON OXIDE WEATHERING
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
1.0 – 3.0 GRAY TO GRAY-BROWN, SILTY FINE SAND WITH ROOTS, ORGANICS, AND GRAVEL (LOOSE
TO MEDIUM DENSE, MOIST) (FILL)
3.0 – 5.5 DARK BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, TRACE ROOTS,
ORGANICS, IRON OXIDE WEATHERING, AND TRACE COBBLES
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
5.5 – 11.5 SP GRAY TO ORANGE-GRAY, FINE TO COARSE SAND WITH GRAVEL, ROOTS, IRON OXIDE
WEATHERING, COBBLES, AND TRACE SILT (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED 2.0, 5.0, AND 10 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 11.5 FEET ON 2/5/21
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
DJO:DPN NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 1227220
FIGURE 6
TEST PIT SEVEN
0.0 – 3.0 GRASS UNDERLAIN BY LIGHT BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH
ROOTS, ORGANICS, AND GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
3.0 – 6.0 ORANGE-BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, TRACE
COBBLES, IRON OXIDE WEATHERING, AND ROOTS
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
5.5 – 11.5 SP GRAY TO ORANGE-GRAY, FINE TO COARSE SAND WITH GRAVEL, ROOTS, IRON OXIDE
WEATHERING, COBBLES, AND TRACE SILT (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED 2.0, 5.0, AND 10 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 11.5 FEET ON 2/5/21
TEST PIT EIGHT
0.0 – 4.5 GRASS UNDERLAIN BY DARK BROWN TO GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH
ROOTS, GRAVEL, ORGANICS, AND IRON OXIDE STAINING
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
4.5 – 7.0 SM BROWN TO GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL, IRON OXIDE
WEATHERING AND TRACE ROOTS (MEDIUM DENSE TO DENSE, MOIST TO WET)
7.0 – 10.5 SM GRAY TO GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE IRON OXIDE STAINING
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED 6.0 AND 10.0 FEET
GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 8.0 FEET
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 10.5 FEET ON 2/5/21
TEST PIT NINE
0.0 – 4.5 GRASS UNDERLAIN BY DARK BROWN TO GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH
ROOTS, GRAVEL, ORGANICS, AND IRON OXIDE STAINING
(LOOSE TO MEDIUM DENSE, MOIST) (FILL)
4.5 – 8.0 SM ORANGE-BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE GRAVEL, IRON
OXIDE WEATHERING AND TRACE ROOTS (MEDIUM DENSE TO DENSE, MOIST TO WET)
8.0 – 10.5 SM GRAY TO GRAY-BROWN, SILTY FINE TO MEDIUM SAND WITH TRACE IRON OXIDE STAINING
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED 10.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
SLIGHT TEST PIT CAVING WAS ENCOUNTERED AT 8.0 FEET
TEST PIT WAS COMPLETED AT 10.5 FEET ON 2/5/21
TEST PIT TEN
0.0 – 3.0 GRASS UNDERLAIN BY ORANGE BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL,
TRACE COBBLES, AND IRON OXIDE WEATHERING (LOOSE TO MEDIUM DENSE, MOIST) (FILL)
3.0 – 5.5 SP GRAY TO ORANGE-GRAY, FINE TO COARSE SAND WITH GRAVEL, ROOTS, IRON OXIDE
WEATHERING, COBBLES, AND TRACE SILT (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE NOT COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 5.5 FEET ON 2/5/21