HomeMy WebLinkAboutMiscTECHNICAL INFORMATION REPORT
FOR
SU'S MULTI-FAMILY TOWNHOMES
Located at 16826 1081h Avenue SE
Renton, Washington 98055
August2015
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 ............................................................. ?
2.1.1 Core Requirements ..................................................................... 7
2.1.2 Special Requirements .................................................................. 8
3.0 Off site Analysis ............................................................................... 10
3.1 Standard Requirements .................................................................... 10
3.2 Scope of Analysis .......................................................................... 10
3.2.1 Resource Review ..................................................................... 10
3 .2.2 Field Inspection ....................................................................... I 0
3.2.3 Drainage System Description and Problem Descriptions ....................... JO
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 WaterQualityFacilities .................................................................. 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
I 0.1 Maintenance Recommendations ....................................................... 18
2
LIST OF FIGURES
Figure 1-Site Location
Figure 2-TIR Worksheet
Figure 3 -Existing Conditions (Existing Drainage)
Figure 4 -Developed Conditions (Proposed Drainage)
Figure 5 -Soils Map
Figure 6-Flow Chart for Determining the Type of Drainage Review
Required
Figure 7 -Flow Control Application Map
Figure 8 -Groundwater Protection Areas
Figure 9 -Downstream Analysis Map
Figure IO -Downstream Analysis Worksheet
Figure 11 -Bond Quantities Worksheet
Figure 12-Maintenance and Operations Manual
LIST OF TABLES
Table I -Pre-Developed Conditions Surface Areas
Table 2 -Developed Conditions Surface Areas
LIST OF APPENDICES
APPENDIX A -Geotechnical Report
APPENDIX B -Drainage Plans
APPENDIX C -Stormwater Modeling Report (MGSFlood Program Input and Output)
APPENDIX D -Declaration of Covenant for Maintenance and Inspection of
Flow Control BMPs
3
1.0 PROJECT OVERVIEW
1.1 General
The Su's Twonhomes Project proposes to construct a three unit, multi-family
residential development, along the 1081h Avenue SE between SE 1701h St and
SE168'h St block, in Renton, WA (See Figure 1 -Vicinity Map). The
development will include the construction of three, two story, multi-family
townhome, pathways, landscaping, and associated right of way improvements
along the Project frontage. See Figure 2 (TIR Worksheet) for summary of the
Project.
1.2 Pre-developed Condition
The Project site is bounded by 108th Avenue SE to the east, Benson Estates to the
north, Heron Glen Condomium to the south, and single family homes to the west.
Currently, a single-family residence, accessed via a paved driveway on its north
site, occupies about one-fifth to on fourth of the site, with detached storage sheds
and chicken coops lining the north boundary. The open space of the site is mostly
covered by over-grown grass and brush with scattered trees lining the north and
the east boundaries. According the topographic survey plan of the site, the terrain
within the site generally slopes down to the south at grade varying from about 5%
to 20%. Most of the stormwater runoff from the existing site is either infiltrated
on site, sheet flows southeast direction toward the existing stormwater system
along 108th Avenue SE. See Figure 3 for existing site conditions. See Table
#I below for Pre-Developed Condition Surface Areas.
T bl I P D a e -re-eve ope d C d"ti S f on 1 on ur ace A reas
Type of Land Covers Area (ac)
-
Ex. PGIS 0.0430
Ex. NPGIS 0.0358
Ex. Pervious 0.6712
Total Lot Area 0.7500
1.3 Proposed Development
The Project proposes to construct three, two story, multi-family townhome
buildings. Other proposed site features include concrete walkway, a common
play area, ROW frontage improvements, and associated landscaping
4
improvements. See Table #2 below for proposed developed conditions surface
areas and Figure 4 for developed site conditions.
T bl 2 D a e -eve ooe d C d"ti S f A on 1 on ur ace reas
Tvoe of Land Covers Area (ac)
Dev. PGIS 0.2502
Dev. NPGIS 0.1956
Dev. Pervious 0.3042
Total Area 0.7500
1.4 Proposed Storm Drainage Facilities
The majority of the building downspouts will be tightlined to detention vault
#1 for flow control located below common play area. Runoff from landscape is
expected to infiltrate. In the event that runoff from landscape areas occurs; the
site has been graded to sheet flow to one of the two detention vaults. Other hard
surfaces onsite, including walkways and the driveway will sheet flows to
combined wet/dry detention vault located under driveway. See Figure 4 for vault
location. Combined wet/dry detention vault provided flow control and water
quality treatment for pollution generated impervious area (PGIS) for this project.
See Appendix C for MGSFlood calculations and results.
1.5 Soils
Based on a geotechnical study performed by Liu and Assocaites Inc. (See
Geotechnical Report in Appendix A). The Geologic Map of the Renton
Quadrangle, King County, Washington, by D.R. Mullineaux, published by U.S.
Geological Survey in 1965, was referenced for the geologic and soil conditions at
the project site. According to this publication, the surficial soil unit at and in the
vicinity of the subject residence site is mapped as Ground Moraine (Qgt) deposits.
The ground moraine soil unit is composed of a thin layer of ablation till over
lodgmont till deposit, plowed directly under glacial ice during the most recent
glacial period. The lodgmont till deposits are composed of a compact mixture of
unsorted clay, silt, sand gravel and cobble, commonly referred to as "hard pan".
The City of Renton Amendments (City Amendments) to the King County Surface
Water Design Manual (KCSWDM) identities the site as being Alderwood
gravelly sandy loam AgC, See Figure 5. In accordance with the KCSWDM,
subsurface conditions of the site were explored with five test pits. The test pits
encountered a layer ofloose, organic topsoil, about 10 to 18 inches thick,
mantling the site. Underlying the topsoil is a layer of ablation till of brown to
5
yellowish-brown to rusty-brown, medium-dense, silty fine sand with trace to
some gravel, from 1.8 to 2.5 feet thick. This ablation till layer is underlain to the
depths explored by a lodgmont till deposit of light-gray, very dense, cemented,
gravelly, silty, fine sand with occasional cobble. This soil classification is not
suitable for infiltration. See Appendix A for a copy of the Geotechnical Report
for additional soil information.
6
2.0 CONDITIONS AND REQUIREMENTS SUMMARY
2.1 Conditions and Reqnirements
Storm water management for the project will be provided in accordance with the
City Amendments and KCSWDM requirements. The flow chart in Figure 6 -
Flow Chart for Determining the Type of Drainage Review Required in
conjunction with Table 6 -Requirements Applied Under Each Drainage Review
Type in the City Amendments, provides the framework to determine which core
Requirements apply to the Project. These figures are provided in the City
Amendments. as Figure 1.1.2.A and Table 1.1.2.A . The Project will add/replace
more than 2,000 square feet of impervious surface; therefore, the Project must
comply with Core Requirements #I -#8 and Special Requirements #1 -#6.
2.1.1 Core Requirements
Core Requirement #1: Discharge at Natural Location
• Storm water plans have been prepared; a copy is in Appendix B. The
stormwater facilities have been designed to the City requirements for flow
control and water quality treatment through the use of retention/detention
vaults. Any runoff not detain by the vaults will be discharged at the
"natural discharge location", the City of Renton stormwater system.
Core Requirement #2: Ojfsite Analysis
• All projects are required to perform an offsite analysis per section I .2.2.1
of the City Amendment. A Level ] analysis has been performed and
presented in Section 3 .0 of this report.
Core Requirement #3: Flow Control
• The project is located in a flow control duration standard (Forested
Conditions) area based on the City of Renton Flow Control Application
Map, See Figure 7. Flow control will be provided by two detention vaults.
Detention vault will be located under the common area and combined
wet/dry detention vault will be located under the driveway. The
continuous simulation model MGSFlood was used to design the detention
facilities. The input and output generated from this analysis is included in
Appendix C.
Core Requirement #4: Conveyance System
• Runoff from the building roofs will sheet flows to the downspout and
piped to the detention vault 1. Runoff from walkway and driveway sheet
flows to the combined wet/dry detention vault 2 located under driveway.
See figure 4 for vaults location.
7
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
required to prepare a Stormwater Pollution Prevention and Spill (WSPPS)
Plan to comply with Section 2.3.1.1 of the City Amendment. 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 has 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 the Owner prior to permit approval, per
Section 1.2.7 of the Manual Amendment. See Section 9.0 of this report
for Bond Quantities.
Core Requirement #8: Water Quality
• Runoff Treatment is required for this project pollution generating
impervious surfaces (PGIS). This project contains PGIS within the
driveways and access pathway to the townhomes. The Project will utilize
combined wet/dry detention vault to treat storm water runoff from the
PGIS. The water quality design flow rate at or which 91 % of the runoff
volume will be treated was estimating using the MGSF!ood and is
included in Appendix C.
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
• 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 or
commercial site development permit.
Special Requirement #5: Oil Control
• Not Applicable. This site is not classified as high-use roadway.
8
Special Requirement #6: Aquifer Protection Area
• The Project is not located within the Aquifer Protection Area, Zone I. No
infiltration bmp is proposed for this project. Not applicable.
9
3.0 OFF-SITE ANALYSIS
3.1 Standard Requirements
Offsite analysis is required for all projects per Section 1.2.2 of the
City Amendment. 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 9 the offsite analysis study area extends from
point 1 to point 13. Point 13 is approximately y.; mile downstream
from the Project site.
3.2.1 Resource Review
• City ofRenton's storm and Surface Water Utility System Map.
3.2.2 Field Inspections
The study area was observed on July 10, 2015. Atmospheric conditions were
sunny. No evidence of downstream conveyance issues was identified. The site
conditions generally appeared to match the surveyed base map.
3.2.3 Drainage System Description and Problem Descrisptions
Figure 9 shows a map of the downstream system reviewed. Figure 10 includes a
description of each drainage system element. No downstream drainage issues
were identified by the Level I 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 flow control BMP's are
proposed.
10
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 I -Vicinity Map. The
site is situated on a gentle, southerly-declining. The site is a rectangle-shaped
land elongated in the east-west direction. It is bounded by 108 1h Avenue SE to the
east and adjoined by the residential development to the north, south and west.
According to the topographic survey plan of the site, the terrain within the site
generally slopes down to the south at grade varying from about 5% to 20%.
Currently, a single family residence, accessed via a paved driveway on its north
site, occupies about the one-fifth to one-fourth of the site, with detached storage
sheds and chicken coops lining the north boundary. The open space of the site is
mostly covered by over-grown grass and brush with scattered trees lining the
north and west boundaries. There is no existing drainage features on the site.
Storm water runoff either infiltration or sheet flows to the City's drainage system
along I 08 1h Avenue SE. See Figure 3 for an existing site hydrology conditions.
4.2 Proposed Site Hydrology
The majority of the building downspouts will be tightlined to the detention vault I
for flow control treatment. Runoff from landscape is expected to infiltrate. In the
event that runoff from landscape areas occurs, the site has been graded to sheet
flow to the proposed combined wet/dry detention vault. Other impervious
surfaces onsite, including walkways and driveway has been graded to sheets flows
to combined wet/dry detention vault. See Figure 4 for developed condition flow
patterns.
4.3 Performance Standards
The Project is located in a flow control duration standard (Forested Conditions)
area based on the City of Renton Flow Control Application Map, See Figure 7.
The continuous simulation model MGSFlood was used to design the detention
and water quality facilities. Runoff calculations showing that the developed site
meets and exceeds the flow control duration standard required by the City. The
input and output generated from this analysis is included in Appendix C.
For water quality, the project utilized wet detention vault to treat stormwater
runoff from the pollution generating impervious surfaces (PGIS). The water
quality design flow rate at or which 91 % of the runoff volume will be treated was
estimating using the MGSFlood Model and is included in Appendix C.
II
4.4 Flow Control Facilities
Flow control for the non-pollution generating surfaces (rooftops) will be provided
detention vault I. Flow control for the pollution generating surfaces (walkways
and driveway) through combined wet/dry detention Vault 2. Sizing the two vaults
using MGSFlood continuous simulation model and the results is in Appendix C of
this report.
4.5 Water Quality Facilities
This project contains PGIS within the driveways and walkway to the townhomes.
The Project will utilize combined wet/dry detention vault to treat stormwater
runoff from the PGIS. The water quality design flow rate at or which 91 % of the
runoff volume will be treated was estimating using the MGSFlood and is included
in Appendix C.
12
5.0 CONVEYANCE SYSTEMS ANALYSIS AND DESIGN
5.1 Standard Requirements
The Manual Amendment sates that, "New pipe systems shall be designed with
sufficient capacity to convey and contain (at minimum) the 25 year peak flow."
All proposed conveyance systems will meet or exceed this requirement.
5.2 Proposed Conveyance System
Rooftops runoff from the three townhomes will be collected in downspout
tightlines and piped to detention vault 1 and release at control rate into the City's
drainage system.
In general, runoff from non-building areas will either infiltrate into the ground
through landscape area or will sheet flow into combined wet/dry detention vault 2
and release at control rate into the City's existing drainage system.
The project will utilize a 6-inch dia. PVC at 0.5% slope to tightline the building
roofs runoff to detention vault 1 located under the play area. Since the release
rate for both detention vaults are less than 0.10 cfs, the project will utilize an 8-
· inch dia. PVC at 0.5% slope to tighline the release flow to the City's drainage
system. See Appendix B for drainage plans.
13
6.0 SPECIAL REPORTS AND STUDIES
6.1 Geotechnical
A copy of the report titled, "Geotechnical Investigation," dated June 20, 2015 by
Liu & Associates, Inc. is provided in Appendix A.
14
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.
15
8.0 CSWPPP ANALYSIS AND DESIGN
8.1 ESC Plan
A preliminary ESC plan has been provided on Sheet ECOi through Sheet EC03 of
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 Section 2.3.1.1 of the City Amendment.
Erosion control measures indicated on the preliminary plan include: marking
clearing limits and the use of straw wattles. The site is generally flat and no
special considerations for soil erosion have been outlined in the Geotechnical
Report, so erosion potential is assumed to be low. Sediment control measures
indicated on the preliminary plan include a stabilized construction entrance, catch
basin/inlet insert protection, and a portable storage tank and storm water treatment
system. Interceptor swales around the perimeter of the site will collect site runoff
and convey it to the portable storage tank and treatment system.
SWPPSP!an
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
Section 2.3.1.1 of the City Amendment.
16
9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND
DECLARATION OF COVENANT
9.1 Bond Quantities Plan
A Bond Quantities Worksheet is provided in Figure 11.
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 two vaults and catch basins.
17
10.0 MAINTENANCE AND OPERATIONS MANUAL
10.1 Maintenance Recommendations
Operation and maintenance requirements for the proposed drainage elements and
flow control BMPs have been provided for reference in Figure 12.
18
Figure 1
Site Location
19
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Figure 2
TIR Worksheet
20
KING COUNTY, WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Project Owner 1../1 Ail Sil,, "i11Ni:j W:E.1..
Phone Q..Sb C, ?'L 64/'J-
Address 4qo3 :So JJ./ISTkl. Sf
5"£.ATT}E. i 0/i 1'»1/'l
Project Engineer ::Sft \JO:,_i,. l, 1
Company '1'U
Phone
Part 3 TYPE OF PERMIT APPLICATION
fiQ. Landuse Services
Subdivison / Short Subd. I UPD
D Building Services
MIF / Commerical I SFR
D Clearing and Grading
D Right-of-Way Use
D Other
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report
Type of Drainage Review ~I Targeted
(circle): ge Site
Date (include revision
dates):
Date of Final:
Part6 ADJUSTMENT APPROVALS
I
Part 2 .. PROJECT:LOCATION AND
DESCRIPTION
Project Name / &f, f>WUo?,lfF-4tf
ODES Permit# ----------
Location Township '2-3
Range <J~
Section __ '7--~</ ___ _
Part 4 · OTHERREVIEWs'.AND PERMITS
D DFWHPA
0 COE404
D DOE Dam Safety
D FEMA Floodplain
D COE Wetlands
D Other
D Shoreline
Management
i5Q. Structural
RockeryNaultl __
D ESA Section 7
Site Improvement Plan (Engr. Plans)
Type (circle one): ~/ Modified I
II Site
Date (include revision
dates):
Date of Final:
Type (circle one): ~ / Complex / Preapplication I Experimental I Blanket
Description: (include conditions in TIR Section 2)
Date of Aooroval:
2009 Surface Water Design Manual 1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part7 MONITORING REQUIREMENTS
Monitoring Required:
Start Date:
Yes/e
Describe:
Completion Date:
Part 8 SI.TE COMMUN.ITV AND DRAINAGE BASIN
Community Plan : --------------
Special District Overlays:------------------------
Drainage Basin: l-oulER.,, G,Q.f;E,N &)1)82...,
Stormwater Requirements: c..o~t;' 12.EGI.AlRt::l'vlEA.l1S:
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
D River/Stream _________ _
D Lake
D Wetlands __________ _
D Closed Depression _______ _
D Floodplain---~-------
D Other A/(;'{
Part 10 SOILS
Soil Type Slopes
D Steep Slope ---------
D Erosion Hazard --------
D Landslide Hazard--------
D Coal Mine Hazard _______ _
D Seismic Hazard _______ _
D Habitat Protection--~-----
D A/jA'
Erosion Potential
t!~c 7 t:, ,b. 20 6 (.,Jc,v
D High Groundwater Table (within 5 feet) D Sole Source Aquifer
D Other D Seeps/Springs
D Additional Sheets Attached
2009 Surface Water Design Manual 1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
'
Part11 DRAINAGE DESIGN LIMITATIONS
REFERENCE LIMITATION/ SITE CONSTRAINT
1:1 Core 2 -Offsite Analysis
1:1 Sensitive/Critical Areas
l:J SEPA
1:1 Other
1:1
1:1 Additional Sheets Attached
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold DischarQe Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply)
Discharqe at Natural Location Number of Natural Discharae Locations:
Offsite Analysis Level: GJi 2 / 3 dated:
Flow Control Level: 1 '/Ps 3 or Exemption Number
/incl. facilitv summary sheet) Small Site BM s
Conveyance System Spill containment located at:
Erosion and Sediment Control ESC Site Supervisor:
Contact Phone:
After Hours Phone: _
Maintenance and Operation Responsibility: ~Public
If Private, Maintenan~,a Loa Reauired: Yes I No
Financial Guarantees and Provided: ~/No
Liabilitv
Water Quality Type: o~.' Sens. Lake / Enhanced Basicm / Bog
(include facility summary sheet) or Exemp .
Landscape ManaQement Plan: Yes / No
Special ReQuirements (as applicable)
Area Specific Drainage Type: CDA I SDO /MOP/ BP/ LMP / Shared Fae. I None
Requirements Name:
Floodplain/Floodway Delineation Type: Major / Minor / Exemption te}
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities Describe: NMe..
Source Control Describe landuse:
(comm./industrial landuse) Describe any structural controls:
2009 Surface Water Design Manual 1/9/2009
3
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
-
Oil Control High-use Site: Yes~
Treatment BMP:
Maintenance Agreement Yes 16}
with whom?
Other Drainaae Structures
Describe: No Et--,'<;.\;~ ~"1.~ fi,,ili /.iv,/
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION AFTER CONSTRUCTION
~Clearing Limits ~ Stabilize Exposed Surfaces
12!1' Cover Measures l:a"Remove and Restore Temporary ESC Facilities
s;I-Perimeter Protection Ga' Clean and Remove All Silt and Debris, Ensure
lilsJ' Traffic Area Stabilization Operation of Permanent Facilities
~ Sediment Retention D Flag Limits of SAO and open space
~Surface Water Collection
preservation areas
D Other Oi;I Dewatering Control
~ Dust Control
D Flow Control
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facilitv Summarv and Sketch)
Flow Control Tvoe/Descriotion Water Qualitv Tvoe/Descriotion
~Detention V£41,H· D Biofiltration
D Infiltration ~Wetpool We-± 'J_~
D Regional Facility D Media Filtration
D Shared Facility D Oil Control
~ Flow Control ~Pr110dJI D Spill Control
BMPs D Flow Control BMPs D Other D Other
2009 Surface Water Design Manual 1/9/2009
4
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 15 EASEMENTS/TRACTS ·Part16 STRUCTURAL ANALYSIS
D Drainage Easement ~ Cast in Place Vault
D Covenant D Retaining Wall
D Native Growth Protection Covenant D Rockery > 4' High
D Tract D Structural on Steep Slope
IZ3. Other D Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information prl!\vided here is accurate. I / ":.!f, , , o _ ~1n lf·
Sianed/Date
2009 Surface Water Design Manual 1/9/2009 s
Figure 3
Existing Conditions (Existing Drainage)
21
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Existing Site Aerial Map
RentonMapSupport@R entonwa .gov
07/29/20 15
This map i~ 8 u::,er t;enerote(: static out;:,ut frum ;:iri lr.terne: mi.ippiriiJ !::ite i.ind
is f or rderence o nly Dat.:1 lvyers thrJt a;x:ercJr ori tr,is ,.-nap m<:iy ur mi.l/ ne t LJt
accurate, ClJrrf:!r•t or utl1E:;r,'.'l~E: rdi~~ble.
THIS MAP IS NOT TO BE USED FOR NAVIGAT ION
Legend
City and County Boundary
Other
[.~ Cityof Renton
Addresses
Parcels
1st Floor
1st Floo r
2nd Floor
1st Floor
Other Bu ildings
Bu ildings
Note s
16826 108th Ave. SE
Renton , WA 98055
0
City o.!.&etrf o fl {)
Finan ce & IT Division
Figure 4
Developed Conditions (Proposed Drainage)
22
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PROPOSED STORM SEVIIER LINE ST -ST
PROPOSED UNDERDRAIN
PROPOSED MANHOLE
EXISTING STORM SEVIIER LINE
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0.5% tr ST
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c,,.uc: sfaucfuRE,
j J I I
DRAINAGE PROFILE
DRAINAGE PLAN
~I I -I
158 DEVELOPMENT
15828 108TH AVE SE
RENTON, WA 98055
CALL 2 WORKING
DAYS BEFORE YOU DIG
1-800-424-5555
>it_:_'
3
::OHl_l_
C-6.00
Figure 5
Soils Map
23
ldke
WashJngton
Reference 11-C
SollType-Bh-KpC-PITS-Sk
i:-.:JPotoot,oAn"6>.a""nlvaa ~Agaaa, -K;,DEPc ~Srr
rz::]o,woowawProl8clooAreaBoondi>ry-AgC -E.S c::]Ma -Pk Qso
Aq~ftt,Prot&e~on.....,..zo....,1 -AgD -E.C -Ng -Pu !E:Jrc,
D/>,qL.<!erProloc~onA,eoZo<>e11,1oO,fi&d-Ak.F -E\oQ -Nk -Py -Ur
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-AmC~l~/o. -Or -RdE -w, -An-lnC_Os_Fle
-BeC-lnDl!lli:JOvC-Flh .a.o iliJ~pB •=-~
Spil Survey Dale 01/08.2'.JlL
"®' 2 •--==---==------•Miles
TABLE 1.--APPROXIMATE ACREAGE AND PROPORTIONATE EXTENT OF THE SOILS
Soil
Alderwood gravelly sandy loam,
0 to 6 percent slopes-----------
Alderwood gravelly sandy loam,
6 to 15 percent slopes----------
Alderwood gravelly sandy loam,
15 to 30 percent slopes---------
Alderwood and Kitsap soils, very
steep------------------------__ _
Arents, Alderwood material, 0
to 6 percent slopes-------------
Arents, Alderwood material, 6
to 15 percent slopes------------
Arents, Everett material----------
Beausite gravelly sandy loam, 6
to 15 percent slopes------------·
Beausite gravelly sandy loam, 15
to 30 percent slopes------------
Beausi te gravelly sandy loam, 40
to 75 percent slopes------------
Bellingham silt Joam--------------
Briscot silt loam-----------------
Buckley silt loam-----------------
Coastal beaches-------------------
Earlmont silt loam----------------
Edgewick fine sandy loam----------
Everett gravelly sandy loam, 0 to
5 percent slopes----------------
... ,,erett gravelly sandy loam, 5
:.o 15 percent slopes------------
i:verett gravelly sandy loam, 15
to 30 percent slopes------------
Everett-Alderwood gravelly sandy
loams, 6 to 15 percent slopes---
Indianola loamy fine sand, 0 to 4
percent slopes------------------
Indianola loamy fine sand, 4 to
15 percent slopes---------------
Indianola loamy fine sand, 15 to
30 percent slopes---------------
Kitsap silt loam, 2 to 8 percent
slopes--------------------------
Kitsap ·silt loam, 8 to 15 percent
slopes--------------------------
Kitsap silt loam, 15 to 30 percent
slopes--------------------------
Area
Acres
22,000
165,170
14,280
39,000
3,500
6,000
700
7,600
2,700
890
2,610
5,430
12,130
1,105
1,140
2,340
5,500
15,700
6,300
8,405
2,670
2,600
500
5,000
6,550
4,270
Extent
Percent
4.9
37 .1
3. 2
8 .8
• 8
1. 3
. 2
1. 7
.6
. 2
.6
1. 2
2. 7
. 2
. 3
• 5
1. 2
3. 5
1. 4
1.9
.6
.6
.1
1. 2
1. 5
1. 0
Soil
Klaus gravelly loamy sand, 6
to 15 percent slopes----------
Mixed alluvial land-------------
Nei lton very gravelly loamy sand,
2 to 15 percent slopes--------
Newberg silt loam---------------
Nooksack silt loarn--------------
Norma sandy loam----------------
Orcas peat----------------------
Ori di a silt loam----------------
Ovall gravelly loam, O to 15
percent slopes----------------
Ovall gravelly loam, 15 to 25
percent slopes----------------
OVall gravelly loarn 1 40 to 75
percent slopes----------------
Pilchuck loamy fine sand--------
Pilchuck fine s&ndy loam--------
Puget silty clay loam-----------
Puyallup fine sanay loam--------
Ragnar fine sandy loam, 6 to
15 percent slopes-------------
Ragnar fine s.andy loam, 15 to
25 percent slopes-------------
Ragnar-Indianola association,
sloping-----------------------
Ragnar-Indianola association,
moderately steep--------------
Renton silt loam----------------
Ri veru ash-----------------------
Salal silt loam-----------------
Sanunarnish silt loarn-------------
Sea t t le muck --------------------
Shalcar muck--------------------
Si silt loam--------------------
Snohomish silt loam-------------
Snohomish silt loam, thick
surface variant---------------
Sultan silt loam----------------
Tukwila nruck---------··----------
Urb an land----------------------
Woodinville silt loam-----------
Area
Acres
420
1,500
4,660
3,660
3,100
4,230
730
6,630
1,780
3,840
1,250
1,630
640
8,130
4,840
1,540
500
8,110
1,150
5,040
3,700
560
790
8,650
1,220
1,750
2,100
500
3,580
1,730
10,650
~
Tot al-----------------------445,500
Extent
Percent
.1
. 3
1.0
.8
. 7
1.0
. 2
1. 5
.4
.9
.3
.4
.1
1. 8
1. l
.3
.1
1. 8
.3
1.1
.8
.1
.2
1. 9
• 3
.4
. 5
.1
. 8
.4
2. 4
.6
JOO. 0
DESCRIPTIONS OF TI-lE SOILS
This section describes the soil series and map-
ping uni ts in the King County Area, Each soil
series is described and then each mapping unit in
that series. Unless it is specifically mentioned
otherwise, it is to be assumed that what is stated
about the soil series holds true for the mapping
units in that series, Thus, to get full information
about any one mapping unit, it is necessary to read
both the description of the mapping unit and the
description of the soil series to which it belongs.
An important part of the description of each
soi 1 series is the soil profile J that is, the
sequence of layers from the surface downward to
rock or other underlying material. Each series
contains two descriptions of this profile. The
first is brief and in terms familiar to the layman.
The second, detailed and in technical terms, is for
scientists, engineers, and others who need to make
thorough and precise studies of soils. Unless it
is otherwise stated, the colors given in the
descriptions are those of a moist soil.
As mentioned in the section "How This Survey Was
Made/1 not all mapping units are members of a soil
series. Urban land, for example, does not belong
to a soil series, but nevertheless, is listed in
alphabetic order along with the soil series.
Following the name of each mapping unit is a
symbol in parentheses. This symbol identifies the
mapping unit on the detailed soil map. Listed at
the end of each description of a mapping unit is the
capability unit and woodland group in which the
mapping unit has been placed. The woodland desig-
nation and the page for the description of each
capability unit can be found by referring to the
"Guide to Mapping Units" at the back of this survey.
The acreage and proportionate extent of each
mapping unit are shown in table 1. Many of the
terms used in describing soils can be found in the
Glossary at the end of this survey, and more de-
tailed information about the tenninology and methods
of soil mapping can be obtained from the Soi 1 Survey
Manual (~.
Alderwood Series
The Alderwood series is made up of moderately
wel 1 drained soils that have a weakly consolidated
to strongly consolidated substratum at a depth of
24 to 40 inches. These soils are on uplands. They
formed under conifers, in glacial deposits. Slopes
are O to 70 percent. The annual precipitation is
35 to 60 inches, most of which is rainfal 1, between
October and May. The mean annual air temperature is
about 50° F. The frost-free season is 150 to 200
days. Elevation ranges from 100 to 800 feet.
In a representative profile, the surface layer
and subsoil are very dark brown, dark-brown, and
grayish-brown gravelly sandy loam about 27 inches
thick. The substratum is grayish-bro\.'ffi, weakly
consolidated to strongly consolidated glacial till
that extends to a depth of 60 inches and more.
Alderwood soi ls are used for timber, pasture,
berries, row crops, and urban development. They
are the most extensive Soils in the survey area.
Alderwood gravelly sandy loam, 6 to 15 ercent
slopes AgC) .--This soil is rolling. Areas are
irregular in shape and range from 10 to about 600
acres in size.
Representative profile of Alderwood gravelly
sandy loam, 6 to 15 percent slopes, in woodland,
450 feet east and 1,300 feet south of the north
quarter corner of sec. 15, T. 24 N., R. 6 E.:
Al--0 to 2 inches, very dark brown (lOYR 2/2)
gravelly sandy loam, dark grayish brown
(lOYR 4/2) dry; weak, fine, granular struc-
ture; slightly hard, friable, nonsticky,
nonplastic; many roots; strongly acid;
abrupt, wavy boundary. 1 to 3 inches thick.
B2--2 to 12 inches, dark-brown (lOYR 4/3) gravelly
sandy loam, brown (lOYR 5/3) dry; moderate,
medium, subangular blocky structurej slightly
hard, friable, nonsticky, nonplastic; many
roots; strongly acid; clear, wavy boundary.
9 to 14 inches thick.
B3--12 to 27 inches, grayish-brown (2.SY 5/2)
gravelly sandy loam, light gray (2. SY 7 /2)
dry; many, medium, distinct mottles of light
olive brown (2.SY 5/6); hard, friable, non-
sticky, nonplastic; many roots; mediwn acid;
abrupt, wavy boundary. 12 to 23 ·inches thick.
IIC--27 to 60 inches, grayish-brown (2. SY 5/2),
weakly to strongly consolidated till, light
gray (2. SY 7 /2) dry; common, medium, distinct
mottles of light olive brown and yellowish
brown (2.SY 5/6 and lOYR 5/6); massive; no
roots; medium acid. Many feet thick.
The A horizon ranges from very dark brown to
dark brown. The B horizon is dark brown, grayish
brown, and dark yellowish brown. The consolidated
C horizon, at a depth of 24 to 40 inches, is mostly
grayish brown mottled with yellowish brown. Some
layers in the C horizon slake in water. In a few
areas, there is a thin, gray or grayish-brown A2
horizon. In most areas, this horizon has been
destroyed through logging operations.
Soils included with this soil in mapping make up
no more than 30 percent of the total acreage. Some
areas are up to 3 percent the poorly drained Norma,
Bellingham, Seattle, Tukwila, and Shalcar soils;
some are up to 5 percent the very gravelly Everett
and Neil ton soils; and some are up to 15 percent
Alderwood soils that have slopes more gentle or
steeper than 6 to 15 percent. Some areas in New-
cast le Hills are 25 percent Beaus i te soi ls, some
northeast of Duvall are as much as 25 percent Ovall
soils, and some in the vicinity of Dash Point are
10 percent Indianola and Kitsap so~ls. Also
included are smal 1 areas of Alderwood soi ls that
have a gravelly loam surface layer and subsoi 1.
DESCRIPTIONS OF 1HE SOILS
This section describes the soi 1 series and map-
ping uni ts in the King County Area. Each soi 1
series is described and then each mapping unit in
that series. Unless it is specifically mentioned
otherwise, it is to be assumed that what is stated
about the soil series holds true for the mapping
units in that series. Thus, to get full information
about any one mapping unit, it is necessary to read
both the description of the mapping unit and the
description of the soil series to which it belongs.
An important part of the description of each
soil series is the soil profile, that is, the
sequence of layers from the surface downward to
rock or other underlying material. Each series
contains two descriptions of this profile. The
first is brief and in tenns familiar to the layman.
The second, detailed and in technical terms, is for
scientists, engineers, and others who need to make
thorough and precise studies of soils. Unless it
is otherwise stated, the colors given in the
descriptions are those of a moist soil.
As mentioned in the section 11How This Survey Was
Made,11 not all mapping units are members of a soil
series. Urban land, for example, does not belong
to a soil series, but nevertheless, is listed in
alphabetic order along with the soil series.
Following the name of each mapping unit is a
symbol in parentheses. This symbol identifies the
mapping llllit on the detailed soil map. Listed at
the end of each description of a mapping unit is the
capability unit and woodland group in which the
mapping llllit has been placed. The woodland desig-
nation and the page for the description of each
capability unit can be found by referring to the
11 Guide to Mapping Units II at the back of this survey.
The acreage and proportionate extent of each
mapping unit are shown in table 1. Many of the
terms used in describing soils can be found in the
Glossary at the end of this survey, and more de-
tailed information about the terminology and methods
of soi 1 mapping can be obtained from the Soil Survey
Manual (~.
Alderwood Series
The Alderwood series is made up of moderately
well drained soils that have a weakly consolidated
to strongly consolidated substratum at a depth of
24 to 40 inches. These soils are on uplands. They
formed under conifers I in glacial deposits. Slopes
are O to 70 percent. The annual precipitation is
35 to 60 inches, most of which is rainfall, between
October and May. The mean annual air temperature is
about 50° F. The frost-free season is 150 to 200
days. Elevation ranges from 100 to 800 feet.
In a representative profile, the surface layer
and subsoil are very dark brown, dark-brown, and
grayish-brown gravelly sandy loam about 27 inches
thick. The substratum is grayish-brown, weakly
consolidated to strongly consolidated glacial till
that extends to a depth of 60 inches and more.
8
Alderwood soi ls are used for timber, pasture,
berries, row crops, and urban development, They
are the most extensive soils in the survey area.
Alderwood gravelly sandy loam, 6 to 15 percent
slopes (AgC) .--This soil is rolling. Areas are
irregular in shape and range from 10 to about 600
acres in size.
Representative profile of Alderwood gravelly
sandy loam, 6 to 15 percent slopes, in woodland,
450 feet east and 1,300 feet south of the north
quarter corner of sec. 15, T. 24 N., R. 6 E.:
Al--0 to 2 inches, very dark brown (lOYR 2/2)
gravelly sandy loam, dark grayish brown
(lOYR 4/2) dry; weak, fine, granular struc-
ture; slightly hard, friable, nonsticky,
nonplastic; many roots; strongly acid;
abrupt, wavy boundary. 1 to 3 inches thick.
B2--2 to 12 inches, dark-brown (lOYR 4/3) gravelly
sandy loam, brown (lOYR 5/3) dry; moderate,
medium, subangular blocky structure; slightly
hard, friable, nonsticky, nonplastic; many
roots; strongly acid; clear, wavy boundary.
9 to 14 inches thick.
B3--12 to 27 inches, grayish-brown (2.5Y 5/2)
gravelly sandy loam, light gray (2.5Y 7/2)
dry; many, medium, distinct mottles of light
olive brown (2,SY 5/6); hard, friable, non-
sticky, nonplastic; many roots; medium acid;
abrupt, wavy boundary. 12 to 23 ·inches thick.
IIC--27 to 60 inches, grayish-brown (2.5Y 5/2),
weakly to strongly consolidated till, light
gray (2. SY 7 /2) dry; common I medium, distinct
mottles of light olive brown and yellowish
brown (2.5Y 5/6 and lOYR 5/6); massive; no
roots; medium acid. Many feet thick.
The A horizon ranges from very dark brown to
dark brown. The B horizon is dark brown, grayish
brown, and dark yellowish brown. The consolidated
C horizon, at a depth of 24 to 40 inches, is mostly
grayish brown mottled with yellowish brown. Some
layers in the C horizon slake in water. In a few
areas, there is a thin, gray or grayish-brown A2.
horizon. In most areas I this horizon has been
destroyed through logging operations.
Soi ls included with this soi 1 in mapping make up
no more than 30 percent of the total acreage. Some
areas are up to 3 percent the poorly drained Norma,
Bellingham, Seattle, Tukwila, and Sh al car soils;
some are up to 5 percent the very gravelly Everett
and Neil ton soils; and some are up to 15 percent
Alderwood soils that have slopes more gentle or
steeper than 6 to 15 percent. Some areas in New-
castle Hills are 25 percent Beausite soils, some
northeast of Duvall are as much as 25 percent OVall
soils I and some in the vicinity of Dash Point are
10 percent Indianola and Kitsap soils. Also
included are small areas of Alderwood soils that
have a gravelly loam surface layer and subsoil,
Permeability is moderately rapid in the surface
layer and subsoil and very slow in the substratum.
Roots penetrate easily to the consolidated substra-
tum where they tend to mat on the surface. Some
roots enter the substratum through cracks. Water
moves on top of the substratum in winter. Available
water capacity is low. Runoff is slow to medium,
and the hazard of erosion is moderate.
This soil is used for timber, pasture, berries,
and row crops, and for urban development. Capability
unit !Ve-2; woodland group 3dl.
Alderwood gravelly sandy loam, 0 to 6 percent
slopes (AgB) .--This soil is nearly level and
undulating. It is similar to Alderwood gravelly
sandy loam, 6 to 15 perc'e~t slopes, but in places
its surface layer is 2 to 3 ~nches thicker. Areas
are irregular in shape and range from 10 acres to
slightly more than 600 acres in size.
Some areas are as much as 115 percent included
Norma, Bellingham, Tukwila, .ind Shalcar soils, all
of which are poorly drained;: and some areas in the
vicinity of Enumclaw are as much as 10 percent
Buckley soils.
Runoff is slow, and the erosion hazard is
slight.
This Alderwood soil is used for timber, pasture,
berries, and row crops, and for urban development.
Capability uniJ !Ve-2; woodland group 3d2.
Alderwood gravelly sandy loam, 15 to 30 ~erceni
slopes (AgD) . --Depth to the substratum in t is soil
varies within short distances, but is commonly
about 40 inches. Areas are elongated and range
from 7 to about 250 acres in size.
Soils included with this soil in mapping make
up no more than 30 percent of the total acreage.
Some areas are up to 25 percent Everett soils that
have slopes of 15 to 30 percent, and some areas are
up to 2 percent Bellingham, Norma, and Seattle soils,
which are in depressions. Some areas, especially
on Squak Mountain, in Newcastle Hills, and north of
Tiger Mountain, are 25 percent Beausi te and Ovall
soils. Beausite soils are underlain by sandstone,
and Ovall soils by andesite.
Runoff is medium, and the erosion hazard is
severe. The slippage potential is moderate.
This Alderwood soil is used mostly for timber.
Some areas on the lower parts of slopes are used
for pasture. Capability unit Vle-2; woodland group
3d].
Alderwood and Kitsap soi ls, very steep (AkF) . --
This mapping unit is about 50 percent Alderwood
gravelly sandy loam and 25 percent Kitsap silt
loam. Slopes are 25 to 70 percent. Distribution
of the soils varies greatly within short distances.
About 15 percent of some mapped areas is an
included, unnamed, very deep, moderately coarse
textured soil; and about 10 percent of some areas
is a very deep, coarse-textured Indianola soil.
Drainage and penneability vary. Runoff is rapid
to very rapid, and the erosion hazard is severe to
very severe. The slippage potential is severe.
These soils are used for timber. Capability
unit VTie-1; woodland group 2dl.
10
Arents, Alderwood Material
Arents, Alderwood material consists of Alderwood
soils that have been so disturbed through urban-
ization that they no longer can be classified with
the Alderwood series. These soils, however, have
many similar features. The upper part of the soil,
to a depth of 20 to 40 inches, is brown to dark-
brown gravelly sandy loam. Below this is a grayish-
brown, consolidated and impervious substratum.
Slopes generally range from O to 15 percent.
These soils are used for urban development.
Arents, Alderwood material, 0 to 6 percent slopes
(AmB). --In many areas this soil is level, as a
result of shaping during construction for urban
faci Ii ties. Areas are rectangular in shape and
range from 5 acres to about 400 acres in size.
Representative profile of Arents, Alderwood
material, 0 to 6 percent slopes, in an urban area,
1,300 feet west and 350 feet south of the northeast
corner of sec. 23, T. 25 N., R. 5 E.:
0 to 26 inches, dark-brown (!OYR 4/3) gravelly
sandy loam, pale brown (lOYR 6/3) dry;
massive; slightly hard, very friable, non-
sticky, nonplastic; many roots; medium acid;
abrupt, smooth boundary. 23 to 29 inches
thick.
26 to 60 inches, grayish-brown (2. SY 5/2) weakly
consolidated to strongly consolidated glacial
till, light brownish gray (2.SY 6/2) dry;
common, medium, prominent mottles of yellowish
brown (lOYR 5/6) moist; massive; no roots;
medium acid. Many feet thick.
The upper, very friable part of the soil extends
to a depth of 20 to 40 inches and ranges from dark
grayish brown to dark yellowish brown.
Some areas are up to 30 percent included soils
that are similar to this soil material, but either
shallower or deeper over the compact substratum;
and some areas are 5 to 10 percent very gravelly
Everett soils and sandy Indianola soils.
This Arents 1 Alderwood soil is moderately well
drained. Permeability in the upper, disturbed soil
material is moderately rapid to moderately slow,
depending on its compaction during construction.
The substratum is very slowly permeable. Roots
penetrate to and tend to mat on the sur.face of the
consolidated substratum. Some roots enter the
substratum through cracks. Water moves on top of
the substratum in winter. Available water capacity
is low. Runoff is slow, and the erosion hazard is
slight.
This soil is used for urban development. Ca-
pability unit IVe-2; woodland group 3d2.
Arents, Alderwood material, 6 to 15 percent
slopes (AmC) .--This soil has convex slopes. Areas
are rectangular in shape and range from 10 acres to
about 450 acres in size.
Some areas are up to 30 percent included soils
that are similar to this soil material, but either
shallower or deeper over the compact substratum;
and some areas are 5 to 10 percent very gravelly
Everett soils and sandy Indianola soils.
Runoff is medium, and the erosion hazard is
,odera te to severe.
This soil is used for urban development. Ca-
pability unit IVe-2; woodland group 3d2.
Arents, Everett material (An) .--This is a level
to gently sloping, dark-brown gravelly or very
gravelly sandy loam. It is very .similar to Everett
gTavelly sandy loam (see Everett series), but it
has been disturbed and altered through urban de-
velopment. :Multicolored very gravelly coarse .sand
is at a depth of 8 to 40 inches. Areas a:re common-
ly rectangular in shape, and range from 1 to 120
acres in size.
Representative profile of Arents. Everett mate-
rial, in a home.site, 440 feet west and 100 feet
north of the center of sec. 11, T. 24 N., R. 6 E.:
D to 8 inches, dark-brown (7.SYR 3/4) gravelly
sandy loam, brown (7.SYR 5/4) dry; massive;
soft, very friable, non.sticky, nonplastic;
few roots; 30 percent gravel content;
slightly acid; clear, smooth boundary. 8 to
14 inches thick,
8 to 60 inches, grayish-brown and light olive-brown
(2.SY 5/2 and 5/4) very gravelly coarse
sand, light gray and light yellowish brown
(2.SY 7/2 and 6/.1) dry; single grain; loose,
non.sticky, nonplastic; few roots; 55 percent
gravel and 10 percent cobblestone content;
medium acid.
The upper part of the soil
brown to olive brown and from
to very gravelly loamy sand.
from black to olive brown.
ranges from dark
gravelly sandy loam
The substratum ranges
This soil is somewhat excessively drained. The
effective rooting depth is 60 inch es or more.
Permeability i.s rapid, and available water capacity
is low. Runoff is slow, and the erosion hazard
is slight.
This soil is used for urban development. Ca-
pability unit IVs-1; woodland group 3f3.
Beaus i te Seri es
The Beausite series i.s made up of well-drained
soils that are underlain by sandstone at a depth
of 20 to 40 inches. These soi1.s formed in glacial
deposits. They are rolling to very steep. Slopes
are 6 to 75 percent, The vegetation is alder, fir,
cedar, and associated bru.sh and shrubs. The annual
precipitation is 40 to 60 inches, and the mean
annual temperature is about 50 ° F. The frost-free
season ranges from 160 to 190 days. Elevation i.s
600 to 2, DOD feet.
In a representative profile, the surface layer
and the upper part of the subsoil are dark-brown
to dark yellowish-brown gravelly sandy loam that
extends to a depth of about 19 inches. The lower
part of the subsoil is olive-brown very gravelly
sandy loam. Fractured sandstone is at a depth of
about 38 inches.
Beausite soils are used for timber and pasture.
Some areas have been used for urban development.
Beau.site gravelly sandy loam, 6 to 15 percent
slopes (BeC) .--Areas of this soil are 20 acres or
more in size. Slopes are long and convex.
Representative profile of Beausite gravelly
sandy loam, 6 to 15 percent slopes, in woodland,
570 feet south and 800 feet east of the northwest
corner of sec. 29, T. 24 N., R. 6 E.:
01--2 inches to 1/2 inch, undecomposed leaf litter.
02--1/2 inch to D, black (lDYR 2/1) decomposed
leaf litter.
Al--0 to 6 inches, dark-brown (!OYR 3/3) gravelly
sandy loam, brown (lOYR 5/3) dry; weak, fine,
granular structure; soft, very friable,
non.sticky, nonplastic; many roots; slightly
acid; clear, wavy boundary, 5 to 7 inches
thick.
821--6 to 19 inches, dark yellowish-brown (lDYR 4/4)
gravelly sandy loam, light yellowish brown
(lOYR 5/4) dry; massive; .soft, very friable,
non.sticky, nonplastic; many roots; .slightly
acid; clear, irregular boundary. 10 to 15
inches thick.
822--19 to 38 inches, olive-brown (2.5Y 4/4) very
gravelly sandy loam, light yellowish brown
(2.SY 6/4) dry; massive; soft, very friable,
non.sticky, nonplastic; common roots; medium
acid~ abrupt, irregular boundary.
IIR--38 inches, fractured sandstone; medium acid.
The A horizon ranges from very dark grayish
brown to very dark brown and dark brown. The B
horizon ranges from dark grayish brown to dark
yellowish brown and olive brown. It is gravelly
and very gravelly sandy loam and gravelly loam.
Depth to sands tone ranges from 20 to 40 inches.
Some areas are up to 20 percent included Alder-
wood soils, which have a consolidated substratum,
and Ovall soils, which are underlain by andesi te;
some are up to 5 percent the wet Norma and Seattle
soils; some are up to 5 percent Beausi te .soils that
have a gravelly loam surface layer and subsoil; and
some are up to 10 percent soils that are similar to
Beausi te soils, but are more than 40 inches deep
over sandstone.
Roots penetrate easily to bedrock and enter a
few cracks in the bedrock. Permeability is
moderately rapid. Available water capacity is low.
Runoff is meditun, and the hazard of erosion is
moderate.
This soil is used for timber and pasture and for
urban development. Capability unit IVe-2; woodland
group 3d2,
11
Figure 6
Flow Chart for Determining the Type of Drainage Review
Required
24
1.1.2 DRAINAGE REVIEW TYPES Al\D REQUIREMENTS
FIGURE 1.1.2.A FLOW CHART FOR DETERMINING TYPE OF DRAINAGE REVIEW REQUIRED
Is the project a single family residential or agricultural project that results
in ;;,;2,000 sf of new and/or replaced impervious surface or ~7,000 sf of
land disturbing activity, AND meets one of the following criteria?
• The project results in s:10,000 sf of total impervious surface added since
1/8/01, s:5,000 sf of new imperv surface, and :S.35,000 sf of new pervious
surface (for RA, F, or A sites, new pervious surface is ::;52,500 sf or
remainder of site if2"65% is preserved in native vegetation), OR
• The project results in s10,000 sf of total impervious surface added since
1/8/01 and new pervious surface is s35,000 -3.25 x new impervious
surface (for sites ~22,000 sf, use 2.25, and for RA, F, or A sites, increase
by 50% or use remainder of s;te if ~65% is preserved in native vegetation),
OR
• The project results in :s:4% total lmperv surface and ::;15% new pervious
surface on a single parcel site zoned RA or F, or a single/multiple parcel
site zoned A, and all impervious area on the site, except 10,000 sf of it. will
be set back from natural location of site discharge at least 100 ft per
10,000 sf of total impervious surface?
N
Does the project result in ~2,000 sf of
new and/or replaced Impervious
surface or ;z:7,000 sf of new pervious
surface, OR is the project a
redevelopment project on a parcel or
Does the project have the characteristics of one or more of the following
categories of projects (see more detailed threshold language on p. 1~15)?
combination of parcels in which new No
plus replaced impervious surface
1. Projects containing or adjacent to a flood, erosion, or steep slope
hazard area; projects within a Critical Drainage Area or Landslide
Hazard Drainage Area; or projects that propose ;z:?,000 sf (1 ac if
project is in Small Project Drainage Review) of land disturbing
activity.
totals :2:5,000 sf and whose valuation of
proposed improvements (excluding
required mitigation and frontage
improvements) is >50% of the assessed
value of existing improvements?
2. Projects proposing to construct or modify a drainage pipe/ditch that
is 12" or larger or receives runoff from a 12" or larger drainage
pipe/ditch.
3. Redevelopment projects proposing ;z:$100,000 in improvements to
an existing high-use site.
Yes No
Reassess whether
drainage review is
required per Section
1.1.1 (p. 1·9).
Is the project an Urban Planned Development (UPD), OR
does it result in ;z:50 acres of new impervious surface No
within a subbasin or multiple subbasins that are 1------·
hydraulically connected, OR does it have a project site :2:50
acres within a critical aquifer recharge area?
Yes
2009 Surface Water Design Manual
1-11
1/9/2009
Figure 7
Flow Control Application Map
25
lake
Washington
Reference 11-A
~-S~206tt>S1 )
Flow Control Standards
D Peak Ra1e Flow Control Standard (Exis11ng Site Cond1lmns)
-FOW Control Duration Standard (EK,sting SHe Condit<ons)
-Flow Control Duratron Standard{Forested COndilrons}
-FioodProblemFlow
D Unrncorporate<l K1n9 County Flow Control Standards
!:-=-! Renton City L1m11s
L._J Potenhal Annex.abon Area
Youngs
Date:01109/2014
Flow Control Application Map
w~c s@Miil 2 •--=:11--==-----•Miles
Figure 8
Groundwater Protection Area
26
Reference 11-B
Aquifer Protection Area Zones
~Zone1
[2.23 Zeme 1 Modified
~Zone2
Cedar Valley Sole Source Network Structure
Aquifer Project Review Area e Production Well
Stream How Source Area e Spnngbroo~ Spnngs
Cedar Valley Sole Source Aquifer r.::J Renton City L1m1ts c:-:J Po1ent1al Anne.o;at,on Area
l'-1,. ___ _
Groundwater Protection Areas Date: 01/0912014
.~, 2 --==--==------Miles <@UMiiW
Figure 9
Downstream Analysis Map
27
256 0 128
WGS _ 1984_Web_Mercator_Aux iliary_Sphere
256 Feet
D0wnstrear11 Analysis f\/lap
Re ntonMapS upport@Rentonwa .gov
07/27/20 15
This m~r> is a u::.er ~tnera:~L ~ta tic outout t rorn a ri lni ernet me1JJiJing sitf:: .;nd
·~ fo~ 1 f::ference onl·~, Dato 1,1ye.-~ thc1t 8iJ ij8<:ir or, tt-,is 1n21~ rr,a , (F rr1ciy not IA:'
accurcitf:' Cllrrerrt (.,r· other,,.,i:;e r,:;,1 :~1o le.
TH IS MAP IS NOT TO BE USED FO R NAVIGAT ION
Renton Fire Hydra nt
Hydrant Other System
Control Va lve
Water Gravity Pipe
Water Main
Water Service Areas
Lift Station
Clean Outs
Man holes
Casings
Pressurized Ma ins
Otner
-Renton
Private
Gravity Ma ins
Otner
_ Ren ton
-Private
KC Metro Manhol es
KC Pressurized Ma ins
KC Gravi ty Mai ns
Network Structures
Inlet
Manhole
Ut,htyVault
Unknown Struc lure
Detention Fa cilities
P~d
-v au lt
~ Wetlalld
Pipe
Culvert
Open Dra ins
Vi rtual Dra inline
Facil ity Outline
Private Network Structure s
0
City of Rerrton 0)
Finance & IT Division
256 0 128
WGS_ 1984_ Web_Mercator_Auxiliary _ Sphere
Downstrean1 Analysis Map Cont.
256 Feet RentonMapSupport@Re ntonwa.gov
07/27/2015
1 his mi.l;J is c1 user Lleneratec! ~tatic ou1;Jut from ilri lnternei mi:ip~·in9 s1it: c:nd
is tor refererict only Dote l:3yerf thot cl;)i"J 8 <"H on tri~ m.:..:ip may ur rnoy not tJe
c1cvu ra1e cu rrent vr o tnH•Nise reli..itJle
THIS MAP IS NOT TO BE USED FOR NAVI GAT ION
Renton Fire Hydrant
Hydrant Other System
Control Valve
Water Gravity Pipe
Water Main
Water Servi ce Areas
Lift Station
Clean Outs
Manholes
Casings
Pressurized Mains
Other
-Renton
Private
Gravity Mains
0 1/'ler
-Renton
_ Priva!I'
KC Metro Manholes
KC Pressu rized Mains
KC Gra vity Mains
Network Structures
Inlet
Ma nhole
Ut,htyVault
Unknown Structure
Control Structure
Pump Station
X Wa ter Quality
Detention Fa cilities
Pono
Tank
-Vault
..:(_ We~and
Pipe
Cu lvert
Open Drain s
Virtual Dra inline
Facility Outline
Private Net>Nork Structures
0
Cityo~Qfl (jJ
Finance & IT Division
Figure 10
Downstream Analysis Worksheet
28
OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE
SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2
Basin: Lo..ve-r Gi<'e~V' \<i llev' Subbasin Name: :P"n~ Cve.,e...k. Subbasin Number:
Symbol
see map
~
3
4
5'
"
7
8
'I
10
II
,z.
t '3
, Drainage ... ·
coirlponiint t9i>e,
illarrie, and Size
Type: sh~et flow, Swale,
stream, chim~E!I, J)ipe,
pond; Siz8:.diameter,
-surface area
1'2.q CON.C.
Pl~lrl> Fl.CIA>
1-Z." C.N\>
PIPl:"1> FLbW
12.'' C.MP
1'1 rES>.. F'Lt>W
11-'1 UNI<-,
PIP..-1> f"'LDW
I@." C PfiiP/LC:..f'f!'
PIPED t=>,n~,
18" C.PsP/LC.f'~
Pl f"E'D -F<.oui
18" C.PEf' /1.( .. 1t"e
Pu"''"P Bl><
I~" cPEP/t-e.f>"C
PIPIS'.t>o Fl""'
1'2.'' C. NI i'
PIPEI> Plew
l'a" Cl"\f>
P1PE.P Fl.Ow
IS" CM?
f' I Pl<'O Fl ~.,
l'o'' c.MP
..£.\£'.E:.l> ~Lo....i
!.'tli>f<:MW.-,.YE.12.
DI 1'41 • C~A IOI EL
Drainage:.' JS1ope
Component•.
oestrlptiob
dr~iriage basin 1 vegetapon,
co*er, detith, lype of S'ehSitiv~
· area, vollime ,
c.S TYPw l
C.~ ,YPe-
c.e. ,YP't: 1
C.6 TYPc.l 'l"IH
<:.-1!, TYP6' .I Mlt
c e. ,yr e a Ml+
CB 'TYPtc \
C.~ iYPE I
cg 1'YPc.i M\!
c. e. "TYi"'€ ~ "4 H
c.:i. 'TY.PE' -i Mlt
o"'+fu\l ,\,.. Pitc.\,\
S'fD41.MWAT"~
t>r"f t:.\.1-
%
UN~.
UN\<-
Ut.11'-.
'-INK.
IAN'(..
l,(N~
UNI:.
UN.K.
l,lt.)IL...
llNl<.,
\.IN!''
l,\lol\l,,
UNK,
Distarice.
from site
discharge
!4 ml = 1..320-ft.
toi.,o'
,If,'-/, <10'
-;J.'85.,:,.1 1
35'" -'g 'L'
4'1'1.ol.f'
!, S"'I, .;i <\ •
";;1(., ."7~'
73'i.oil'
q,~.~01
"IS-0.1.11'
I 0"30, 111 1
1108,5"0 1
, 81'3.s-c/
:e•iQlj!Je~ations of field
l?C.:fhs~lidor, resource
tHre~liwef or resident
• c.qns:tri~~O!']S, l..ind~ capacify1' po.~~ir9,tf' .T;~tri_b~ta~· area .. ,like.llt,ood of problem,
OvertoPP.inQ(~.oodinQ .• ~abitat P,r6r:gal1ismj.;:,·, 1,:.0~~!1low ~~~hw8ys; potential Impacts
deSln:J~h~SC<?u~ng,.ban~tloUQh.i_rig·,~;~~· · :.·,. ,,,. ·· "
sedim~ntatibrl 1-incision, oU181° arosiOll
UtJl<-. UNIC., N/4
UNl<..
\,\ "'""· N/A
t.,"11:::. UNI'-· rvM
Ulol~. U(l)K. N/4,
IAN"-. lAIJI(.. ,.J/A.
CA lJI(.. '-\NI(.. N/A
1.41\1\<:. l.\l\lK. tJIA
LH11'~ .. Ur.II(, rJ/JJ,.
~NI<'. IIIN K.. t,JJ A,
1.1"1~. U"')'.,, Nllt
1..1NK. I,( rJ)t,.. rJ/ A,
IAN/(... 1.11'11'. N/~
NONI= fJON~ e;.(l)p OF ANA\..'(SlS
NO $1•N 01"' ~10..::i
o,~ ov~ ,e>tP•~~ --
1/9/2009
Figure 11
Bond Quantities Worksheet
29
UNIT BID ITEM QUNTITIES UNIT PRICE TOTAL
PREPARATION 1500 $1.00 $1,500.00
LS CLEAN AND GRUBBING 2000 $1.00 $2,000.00
LS REMOVING EXISTING STRUCTURE
GRADING
C.Y ROADWAY EXCAVATION INCL. HAUL 2715 $10.00 $27,150.00
TON GRAVEL BORROW INCL. HAUL 1123 $20.00 $22,460.00
L.S LANDSCAPE GRADING 5000 $1.00 $5,000.00
DRAINAGE
L.F UNDERDRAIN PIPE 6 IN. DIAM 470 $5.00 $2,350.00
EACH Manhole 2 $3,000.00 $6,000.00
L.F PVC STORM SEWER PIPE 8 IN DIAM 220 $40.00 $8,800.00
L.F PVC STORM SEWER PIPE 12 IN DIAM 50 $50.00 $2,500.00
C.Y EXCAVATION FOR DRAINAGE 100 $8.00 $800.00
I.S DETENSION VAULT 1 110000 $1.00 $110,000.00
DETENSION VAULT 2 200000 $1.00 $200,000.00
SANITARY SEWER
L.F DUCTILE IRON PIPE 8 IN. DIAM 250 $80.00 $20,000.00
EACH TEE, D.I. 6 IN I 3 $300.00 $900.00
EACH MAN HOLE, TYPE 2 $4,000.00 $8,000.00
C.Y EXCAVATION FOR DRAINAGE 120 $8.00 $960.00
WATER LINES
L.F PIPE, WATER MAIN, D.I., CL 52, 6 IN, RJ, INCL. FITTINGS 300 $80.00 $24,000.00
EACH RESETTING EXISTING HYDRANTS 1 $5,000.00 $5,000.00
EACH VALVE, GATE, 6 IN 2 $2,000.00 $4,000.00
TON MINERAL AGGREGATE, TYPE 17 3 $40.00 $120.00
EACH WATER METER 6 $2,000.00 $12,000.00
STRUCTURE
EACH BLOCK WALL (2.5'X2.5'X5') 260 $750.00 $195,000.00
SURFACING
TON CSBC 220 $30.00 $6,600.00
TON ASPHALT TREATED BASE 390 $50.00 $19,SOO.OO
CEMENT CONC. PAVEMENT
C.Y. CEMENT CONC. PAVEMENT 100 $250.00 $25,000.00
$0.00
HOT MIX ASPHALT
TON HMA CL. 1/2 IN. PG 64-22 220 $85.00 $18,700.00
LS IRRIGATION AND WATER DISTRIBUTION 1 $15,000.00 $15,000.00
L.F IRRIGATION SLEEVE 300 $15.00 $4,500.00
L.S TEMPORARY TRAFFIC CONTROL 10000 $1.00 $10,000.00
EROSION CNTLAND ROADSIDE RESTORATION
EST TESC (5% OF ESTIMATE) 65000 $1.00 $65,000.00
C.Y TOPSOIL TYPE A-PLANTING SOIL (CY) 10 $35.00 $350.00
C.Y TOPSOIL TYPE A -PLAZA SOIL (CY) 10 $35.00 $350.00
LS LANDSCAPE PLANTS 1 $10,000.00 $10,000.00
EACH INLET PROTECTION 2 $20.00 $40.00
L.F SILT FENCE 820 $10.00 $8,200.00
S.Y STABALIZED CONSTRUCTION ENTRANCE 450 $15.00 $6,750.00
EACH CHECK DAM 5 $10.00 $50.00
BUILDING STRUCTURE
S.F 3 TOWN HOUSE 7500 $120.00 $900,000.00
TOTAL $1,748,580.00
Figure 12
Maintenance and Operations Manual
30
Maintenance standards for closed treatment systems (tanks/vaults).
Maintenance Defect or cOnditlon When Results Expected When
Component Problem Maintenance is Needed Maintenance is Performed
Storage area Plugged air vents One-half of the cross section of a vent is blocked at Vents are open and
any point or the vent is damaged. functioning.
Debris and Accumulated sediment depth exceeds 10% of the AU sediment and debris are
sediment diameter of the storage area for ~ length of storage
vault or any point depth exceeds 15% of diameter.
re~oved from storage area.
(Example: 72-inch storage tank requires cleaning
when sediment reaches depth of? inches for more
than Y, the length of the tank.)
Joints between Openings or voids allow material to be transported All joints between tank/pipe
tank/pipe section into facility. sections are sealed.
{Will require engineering analysis to determine
structural stability.)
Tank/pipe bent out Any part of tank/pipe is bent out of shape for more Tank/pipe is repaired or
of shape than 10% of its design shape. replaced to design
(Review required by engineer to determine specifications.
structural stability.)
Vault structure: Cracks are wider than 12 inch and there is evidence Vault is replaced or repaired to
includes cracks in of soil particles entering the structure through the design specifications and is
walls or bottom, cracks, or maintenance/inspection personnel structuraI1y sound.
damage to frame determine that the vault is not structurally sound.
or top slab
Cracks are wider than Yi inch at the joint of any No cracks are more than
inlev'outlet pipe, or there is evidence of soil Y.-inch wide at the joint of the
particles entering the vault through the walls. inlev'outlet pipe.
Manhole Cover not in place Cover is missing or only partially in place. Any Manhole is closed.
open manhole requires maintenance.
Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper
mechanism not person with proper tools. Bolts into frame have tools.
working less than Y2 inch of thread (may not apply to self-
locking lids).
Cover difficult to One maintenance person cannot remove lid after Cover can be removed and
remove applying normal lifting pressure. reinstalled by one maintenance
Intent: To prevent cover from sealing off access to person.
maintenance.
Ladder unsafe Ladder is unsafe due to missing rungs, Ladder meets design standards.
misalignment, insecure attachment to structure Allows maintenance person
wall, rust, or cracks. safe access.
Maintenance standards for control structure/flow restrictor.
Maintenance Condidon When Results Expected When
Component Defect or Problem Maintenance is Needed Maintenance is Performed
General Trash and debris Accumulation exceeds 25% of sump depth or is Control structure orifice is not
(includes sediment) within 1 foot below orifice plate. blocked. All trash and debris are
removed.
Structural damage Structure is not secure~y attached to manhole wall. Structure is securely attached to
wall and outlet pipe.
Structure is not in upright position; allow up to Structure is in correct position.
10% from plumb.
Connections to outlet pipe are not watertight and Connections to outlet pipe are
show signs of rust. watertight; structure is repaired
or replaced and works as
designed.
Holes other than designed holes are observed in Structure has no holes other than
the structure. designed holes.
Cleanout gate Damaged or missing Cleanout gate is not watertight or is missing. Gate is watertight and works as
designed.
Gate cannot be moved up and do"'11 by one Gate moves up and down easily
maintenance person. and is watertight.
Chain/rod Jeading to gate is missing or damaged. Chain is in place and works as
designed.
Gate is rusted over 50% of its surface area. Gate is repaired or replaced to
meet design standards.
Orificl' plate Damaged or missing Control device is not working properly due to Plate is in place and works as
missing, out-of-place, or bent orifice plate. designed.
Obstructions Trash, debris, sediment, or vegetation blocks the Plate is free of all obstructions
plate. and works as designed.
Overflow pipe Obstructions Trash or debris blocks (or has the potential to Pipe is free of all obstructions
block) the overflow pipe. and works as designed.
Maintenance standards for catch basins.
Maintenance -Uefec:tor ~ :Condition When 11.<Sults Expected Wbeo _
ComJl.onent Problem· MainienaDce is Needed ·Maintenance is ·performed
General Trash and debris Trash or debris is immediately in front of the catch No trash or debris is
basin opening or is blocking inletting capacity of the immediately in front of catch
basin by more than 10%. basin or on grate opening.
Trash or debris (in the basin) exceeds 60% of the No trash or debris is in the
sump depth as measured from the bottom of basin to catch basin.
invert of the lowest pipe into or out of the basin, but
in no case is clearance less than 6 inches from the
debris surface to the invert of the lowest pipe.
Trash or debris in any inlet or outlet pipe blocks more Inlet and outlet pipes are free
than 'l3 of its height. of trash or debris.
Dead animals or vegetation could generate odors that No vegetation or dead animals
might cause complaints or dangerous gases (such as are present within the catch
methane). basin.
Sediment Sediment (in the basin) exceeds 60% of the sump No sediment is in the catch
depth as measured from the bottom of the basin to basin.
invert of the lowest pipe into or out of the basin, but
in no case is clearance less than 6 inches from the
sediment surface to the invert of the lowest pipe.
Structure Top slab has holes larger than 2 square inches or Top slab is free of holes and
damage to frame cracks wider than V.:. inch. cracks.
and/or top slab intent: To make sure no material is running into
basin.
Frame is not sitting flush on top slab (separation of Frame is sitting flush on the
more than% inch of the frame from the top slab). riser rings or top slab and is
Frame is not securely attached. firmly attached.
Fractures or Maintenance person judges that structure is unsound. Basin is replaced or repaired
cracks in basin to design standards.
walls/bottom Grout fillet has separated or cracked wider than Pipe is regrouted and secure at
Yz inch and longer than 1 foot at the joint of any the basin v,all.
inlet/outlet pipe, or there is evidence that soil particles
have entered catch basin through cracks.
Settlement/ Failure of basin has created a safety. function, or Basin is replaced or repaired
misalignment design problem. to design standards.
Vegetation Vegetation is growing across and blocking more than No vegetation blocks the
10% of the basin opening. opening to the ha.sin.
Vegetation growing in inlet/outlet pipe joints is more No vegetation or root gmwth
than 6 inches tall and less than 6 inches apart. is present.
Contamination Oil. gasoline, contaminants. or other pollutants are No pollution is present.
and pollution evident.
(Coordinate removal/cleanup with local water quality
response agency.)
Catch basin Cover not in Cover is missing or only partially in place. Any open Catch basin cover is closed.
cover place catch basin requires maintenance.
Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper
mechanism not person with proper tools. Bolts into frame have less tools.
working than 1h inch of thread.
Catch basin Cover difficult One maintenance person cannot remove lid after Cover can be removed by one
cover to remove applying normal lifting pressure. maintenance person.
(continued) intent: To prevent cover from sealing off access to
maintenance.
Maintenance
c(niipollent
Ladder
Metal grates
(if applicable)
Defector
'sl'roblem
Ladder unsafe
Grate opening
unsafe
Condition When
Maintenance is N~ded
Ladder is unsafe due to missing rungs, insecure
attachment to basin wall, misalignment, rust, cracks,
or sharp edges.
Grate opening is wider than 'l'g inch.
Trash and debris Trash and debris block more than 20% of grate
surface inletting capacity.
Damaged or Grate is missing or components of the grate are
missing broken.
Results Expected 'When
Maintenance is Performed
Ladder meets design
standards and allows
maintenance staff safe access.
Grate opening meets design
standards.
Grate is free of trash and
debris.
Grate is in place and meets
design standards.
APPENDIX A
Geotechnical Report
31
LIU & ASSOCIATES, INC.
Geotechnical Engineering
Mr. Kevin Su
4908 South Thistle Street, Apt. A
Seattle, WA 98118
Dear Mr. Su:
Subject: Geotechnical Investigation
Townhome Buildings
16826-108th Avenue SE
Renton, Washington
L&A Job No. 15-062
Engineering Geology Earth Science
------------· ---~----------~--
June 20, 2015
INTRODUCTION
We understand the development of a residential project is proposed for the subject
property located at the above address in Renton, Washington. The property is a rectangle-
shaped land elongated in the east-west direction. The development plan for the property
is to build three townhome buildings on it, with an existing residence at the west end of
the property to remain. The purpose of this investigation is to explore and characterize
the subsurface conditions of the site, evaluate feasibility of onsite stormwater disposal,
and provide geotechnical recommendations on grading, site stabilization, erosion
mitigation, surface and ground water drainage control, and foundation support to
buildings for the proposed development. Presented in this report are our findings,
conclusion, and geotechnical recommendations.
PROJECT DESCRIPTION
For our use in this investigation, you provided us with a topographic survey plan and a
plat plan of the subject project. According to the plat plan, the new townhome buildings
19213 Kenlake Place NE · Kenmore, Washington 98028
Phone (425) 483-9134 · Fax {425) 486-2746
June 20, 2015
Townhome Buildings
L&A Job No. 15-062
Page2
are to be accessed from 168"' Avenue SE via a joined-use paved driveway traversing
easterly along the south boundary of the site. The townhome buildings will be above-
grade wood-framed structures to be supported on perimeter concrete foundation walls and
interior bearing walls, beams and columns. The site generally slopes down gently to
moderately southward. Minor cut and ;ill may be required for site grading.
SCOPE OF SERVICES
Our scope of services for this study comprises specifically the following:
Review the geologic and soil conditions at the site based on a published geologic
map.
2. Explore subsurface (soil and groundwater) conditions of the site with test pits to
depths where a soil stratum of furn foundation bearing or suitable for infiltration is
encountered, or to the maximum depth (about 10 feet) capable by the backhoe used
in subsurface exploration, whichever is encountered first.
3. Conduct laboratory soil particle size distribution test on two soil samples obtained
from targeted soil layer suitable for infiltration, if encountered by test pits, in
accordance with ASTM D422. The results of the tests will be used to determine
design infiltration rate of targeted soil layer in accordance with USDA Texture
Triangle and Washington State Department of Ecology 2012 Stormwater
Management Manual for Western Washington.
4. Perform necessary geotechnical engineering analysis based on soil data obtained
from test pits.
5. Prepare a written report to present our fmdings, conclusion, and recommendations.
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..
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SITE CONDITIONS
SURFACE CONDITION
The general location of the project site is shown on Plate 1 -Vicinity Map. The site is
situated on a gentle, southerly-declining, high plateau. The site is a rectangle-shaped land
elongated in the east-west direction. It is bounded by 168th A venue SE to the west and
adjoined by residential development to the north, south and east. According to the
topographic survey plan of the site, the terrain within the site generally slopes down to the
south at grade varying from about 5% to 20% .
Currently, a single-family residence, accessed via a paved driveway on its north site,
occupies about the west one-fifth to one-fourth of the site, with detached storage sheds
and chicken coops lining the north boundary. The open space of the site is mostly
covered by over-grown grass and brush with scattered trees lining the north and east
boundaries.
GEOWGIC SETTING
The Geologic Map of the Renton Quadrangle, King County, Washington, by D. R.
Mullineaux, published by U. S.~ Geological Survey in 1965, was referenced for the
geologic and soil conditions at the project site. According to this publication, the surficial
soil unit at and in the vicinity of the subject residence site is mapped as t!f~\i:,~S£~e
~Aep.atss.
The geology of the Puget Sound Lowland has been modified by the advance and retreat of
several glaciers in the past one million years or so and the subsequent deposits and
erosions. The latest glacier advanced to the Puget Sound Lowland is referred to as the
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Vashon Stade of the Fraser Glaciation which had occurred during the later stages of the
Pleistocene Epoch, and retreated from the region some 12,500 years ago.
Tus res reeieseH 112if ie swrmt&1w•nrtt1 • rz r : n r ·u
_.a, plowed directly under glacial ice during the most recent glacial period as the
glacier advanced over an eroded, irregular surface of older formations and sediments.
~~~,.,! .. ~~~~~~~'~f?!1.~?, ~li~,}.il\.s~n~ Wt~ and
s~e,~,,cubbl»s.~dd:>.!:)ul;~;;~¥rE@f\;i;r!,d,\o;,J1S .''AAfppa,i,,;;. The overlying
ablation till is generally in a loose to medium-dense state, and is more compressible and
permeable. It has a compressive strength comparable to that of low-grade concrete and
can stand in steep natural or cut slopes for a long period. TtlaerJodgmo11t..tilJ..caa,.proYi~
ex•llen~ation·,'Support,~ith !i.tJ:lt\SfttlfII1e~t,e~e9tl;!i !:?~ctures. The overlying
ablation till is generally in a loose to medium-dense state, and is more compressible and
permeable. The underlying lodgmont till is very-dense and cemented, with a compressive
strength comparable to that of low-grade concrete, but is also of extremely low
permeability. The lodgmont till can remain stable on steep natural slopes or man-make
cuts for a long period, and can provide excellent foundation support with little or no
settlement.
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SOIL CONDITION
Subsurface conditions of the site were explored with five test pits. The test pits were
excavated on June 12, 2015, with a rubber-track backhoe to depths from 8.0 to 10.0 feet.
The approximate locations of the test pits are shown on Plate 2 -Site and Exploration
Location Plan. The test pits were located with either a tape measure or by visual
reference to existing topographic features in the field and on the topographic survey map,
and their locations should be considered only as accurate to the measuring method used.
A geotechnical engineer from our office was present during subsurface exploration,
examined the soil and geologic conditions encountered, and completed Jogs of test pits.
Soil samples obtained from each soil unit in the test pits were visually classified in
general accordance with United Soil Classification System, a copy of which is presented
on Plate 3. Detailed descriptions of soil layers encountered during by test pits are
presented in test pit logs on Plates 4 through 6.
The test pits encountered a layer of loose, organic topsoil, about 10 to 18 inches thick,
mantling the site. Underlying the topsoil is a layer of ablation till of brown to yellowish-
brown to rusty-brown, medium-dense, silty fine sand with trace to some gravel, from 1.8
to 2.5 feet thick. This ablation till layer is underlain to the depths explored by a lodgmont
till deposit of light-gray, very-dense, cemented, gravelly, silty, fine sand with occasional
cobble.
GROUNDWATER CONDITION
CW 1 J tlll!iDIIU1$M'l~~~ensi$e. The very-
dense, cemented, lodgmont till deposit underlying the site at shallow depth is of
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~~ and would perch storrnwater infiltrating into the more
permeable surficial soils. The amount of and the depth to this near-surface perched
groundwater would fluctuate seasonally, depending on precipitation, surface runoff,
ground vegetation cover, site utilization, and other factors. The perched groundwater may
dry up completely during the dryer summer and early fall seasons and accumulate and rise
in the wet winter and early spring seasons.
GEOLOGIC HAZARDS AND MITIGATION
Landslide Hazard
The site is gently to moderately sloped and is underlain at shallow depth by a very-dense
lodgmont till deposit. This deposit is of very-high shear strength and ts .. highly resi.stant
a~~.slopei/!ilures. Therefore, the potential for deep-seated slides to occur on the site
should be nil.
Erosion Hazard
The surficial topsoil and ablation till soil are more susceptible to erosion, while the
underlying very-dense lodgmont till d-iilll~wion. The site is
mostly gently to moderately sloped and the erosion hazaail:Kefthe.site·1slfouitd·beminimal ifr
e~osed.unpavedi,grgw.:u:his,c.ol,!e~4,with•vegetation. Erosion hazard of the site may be
further mitigated by protect and maintain vegetation cover outside of construction areas.
Areas devoid of vegetation by construction activities should be re-seeded and re-
vegetated as soon as possible. Concentrated storrnwater should not be discharged
uncontrolled onto the ground within the project site or adjacent properties. Storrnwater
over impervious surfaces, such as roofs and paved driveways, should be captured by
underground drain line systems connected to roof downspouts and by catch basins
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installed in paved driveways. ~-~~~~~i~~!~,.~~"·"'
ti1!1ktlined,, to ,.disch1ft,ge · into · a stbrrtf' sewei''syst~ble;;gtQ!'i'nWater.'l disposal,
facilities.
Ii
Seismic Hazard
The Puget Sound region is in an active seismic zone. The site is underlain at shallow
depth by a very-dense cemented lodgmont till deposit of very-high shear strength.
Therefore, the potential for seismic hazards, such as landslides, liquefaction, lateral soil
spreading, to occur on the site should be minimal if the erosion mitigation, drainage
control, and site stabilization measures recommended in this report are fully implemented.
The proposed townhome buildings, however, should be designed for seismic forces
induced by strong earthquakes. Based on the soil conditions encountered by the test pits,
it is our opinion that Seismic Use Group I and Site Class C should be used in the seismic
design of the proposed buildings in accordance with the 2012 International Building Code
(IBC).
DISCUSSION AND RECOMMEND A TIO NS
GENERAL
Based on the soil conditions encountered by test pits excavated on the site, it is our
opinion that the site is suitable for the proposed development from the geotechnical
engineering viewpoint, provided that the recommendations in this report are fully
implemented and observed during and following completion of construction.
Conventional footing foundations constructed on or into the underlying very-dense
lodgmont till soil may be used to support the proposed townhome buildings. Unsuitable
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surficial topsoil and ablation till soil should be stripped within footprint of paved
driveways and areas of structural fill.
The surficial topsoil and weathered soil of the site contain a high percentage of fines and
can be easily disturbed when saturated. To minimize weather-related complications,
grading and foundation construction work should proceed and be completed during the
dryer period from April I" to October 31st, if possible. If construction has to extend
beyond the dry seasons, erosion protection and drainage control measures recommended
in this report should be implemented during winter construction.
TEMPORARY DRAINAGE AND EROSION CONTROL
The surficial weak soils of the site are sensitive to moisture and can be easily disturbed by
construction traffic. A layer of clean, 2-to-4-inch quarry spalls should be placed over
areas of frequent traffic, such as the entrance to and exit from the site, as required, to
protect subgrade soils from disturbance by construction traffic.
A silt fence should be installed along the downhill sides of construction areas to minimize
transport of sediment by storm runoff onto neighboring properties or streets. The bottom
of the filter cloth of the silt fences should be anchored in a trench filled with onsite soil.
Intercepting ditches or trench drains should be installed around the construction areas, as
required, to intercept and drain away storm runoff and near-surface groundwater seepage.
Water captured by such ditches or interceptor trench drains may be discharged into a
nearby storm inlet. The storm inlet should be lined with a non-woven filter fabric sock to
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-------.---------
keep sediment from entering the storm sewer. The sock should be cleaned periodically to
keep it from clogging, and should be removed when construction is completed.
Spoil soils should be hauled off of the site as soon as possible. Spoil soils and imported
structural fill material to be stored onsite should be securely covered with plastic tarps, as
required, for protection against erosion.
SITE PREPARATION AND GENERAL GRADING
Vegetation within construction limits should be cleared and grubbed. Loose topsoil and
weak weathered soil should be completely stripped down to dense to very-dense glacial
till soil within building pads of the residences; while topsoil and unsuitable soil in root
zone should be stripped down to the medium-dense weathered soils and/or dense to very-
dense glacial till soils within paved driveways. The exposed soils should be compacted to
a non-yielding state with a mechanical compactor and proof-rolled with a piece of heavy
earthwork equipment.
EXCAVATION AND FILL SLOPES
Under no circumstance should excavation slopes be steeper than the limits specified by -
local, state and federal safety regulations if workers have to perform construction work in
or near excavated areas. Unsupported temporary cuts greater than 4 feet in height should
be no steeper than lH:lV in topsoil and weathered soil, and may be vertical in the
underlying dense to very-dense glacial till and advance outwash soils if the overall depth
of cut does not exceed 15 feet. Permanent cut banks should be no steeper than 2-1 /4H: 1 V
in topsoil and weathered soil, and no steeper than l-l/2H:1V in the underlying dense to
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very-dense glacial till and advance outwash soils. The soil units and the stability of cut
slopes should be observed and verified by a geotechnical engineer during excavation.
Permanent fill embankments required to support structural or traffic load should be
constructed with compacted structural fill placed over undisturbed. proof-rolled, firm,
native, glacial till soil after the surficial unsuitable soils are completely stripped. The
slope of permanent fill embankments should be no steeper than 2-l/4H:1V. Upon
completion, the sloping face of permanent fill embankments should be thoroughly
compacted to a non-yielding state with a hoe-pack.
The above recommended cut and fill slopes are under the assumption that groundwater
seepage would not be encountered during construction. If groundwater is encountered,
grading work should be immediately halted and slope stability re-evaluated. The slopes
may have to be flattened and other measures taken to stabilize the slopes. Stormwater
should not be allowed to flow uncontrolled over cut and fill slopes. Permanent cut slopes
or fill embankments should be seeded and vegetated as soon as possible for erosion
protection and long-term stability, and should be covered with clear plastic sheets, as
required, to protect them from erosion until the vegetation is fully established.
STRUCTURAL FILL
Structural fill is the fill that supports structural or traffic load. Structural fill for grading
work should consist of clean granular soils free of organic, debris and other deleterious
substances and with particles not larger than three inches. Structural fill should have a
moisture content within one percent of its optimum moisture content at the time of
placement. The optimum moisture content is the water content in the soils that enable the
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soils to be compacted to the highest dry density for a given compaction effort. Onsite
clean soils meeting the above requirements may be used as structural fill. Imported
material to be used as structural fill should be clean, free-draining, granular soils
containing no more than 5 percent by weight finer than the No. 200 sieve based on the
fraction of the material passing No. 4 sieve, and should have individual particles not
larger than three inches.
The ground over which structural fill is to be placed should be prepared in accordance
with recommendations in the SITE PREPARATION AND GENERAL GRADING and
EXCAVATION AND FILL SLOPES sections of this report. Structural fill should be
placed in lifts no more than 10 inches thick in its loose state, with each lift compacted to a
minimum percentage of the maximum dry density determined by ASTM D1557
(Modified Proctor Method) as follows:
Application % of Maximum Dry Density
Within building pads and under foundations 95%
Roadway/driveway subgrade 95% for top 3 feet and 90% below
Retaining/foundation wall backfill 92%
Utility trench backfill 95% for top 4 feet and 90% below
In-situ density of structural fill should be tested with a nuclear densometer by a testing
agency specialized in fill placement and construction work. Testing frequency should be
one test per every 250 square feet per lift.
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BUILDING FOUNDATIONS
Conventional footing foundations may be used to support the proposed townhome
buildings. The footing foundations should be constructed on or into the underlying, very-
dense lodgmont till soil, or on structural fill placed over this undisturbed competent till
basal deposit. Water should not be allowed to accumulate in excavated footing trenches.
Disturbed soils in footing trenches should be completely removed down to native,
undisturbed, lodgmont till soil prior to pouring concrete for the footings.
If the above recommendations are followed, our recommended design criteria for footing
foundations are as follows:
• The allowable soil bearing pressure for design of footing foundations, including
dead and live loads, should be no greater than 3,000 psf if constructed on or into
very-dense lodgmont till soil, and no greater than 2,500 psf if constructed on
structural fill placed over the till basal soil. The footing bearing soils should be
verified by a geotechnical engineer after the footing trenches are excavated and
before the footings poured.
• The minimum depth to bottom of perimeter footings below adjacent final exterior
grade should be no less than 18 inches. The minimum depth to bottom of the
interior footings below top of floor slab should be no less than 12 inches.
• The minimum width should be no Jess than 16 inches for continuous footings, and
no less than 24 inches for individual footings, except those footings supporting
light-weight decks or porches.
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A one-third increase in the above recommended allowable soil bearing pressure may be
used when considering short-term, transitory, wind or seismic loads. For footing
foundations designed and constructed per recommendations above, we estimate that the
maximum total post-construction settlement of the buildings should be 1/2 inch or less
and the differential settlement across building width should be 3/8 inch or less.
Lateral loads on the proposed buildings may be resisted by the friction force between the
foundations and the subgrade soils or the passive earth pressure acting on the below-grade
portion of the foundations. For the latter, the foundations must be poured "neat" against
undisturbed soils or backfilled with a clean, free-draining, compacted structural fill. We
recommend that an equivalent fluid density (EFD) of 300 pcf (pounds per cubic foot) for
the passive earth pressure be used for lateral resistance. The above passive pressure
assumes that the backfill is level or inclines upward away from the foundations for a
horizontal distance at least twice the depth of the foundations below the final grade. A
coefficient of friction of 0.55 between the foundations and the subgrade soils may be
used. The above soil parameters are unfactored values, and a proper factor of safety
should be used in calculating the resisting forces against lateral loads on the buildings.
SLAB-ON-GRADE FLOORS
Slab-on-grade floors, if used for the proposed residential buildings, should be placed on
firm subgrade soil prepared as outlined in the SITE PREPARATION AND GENERAL
EARTIIWORK and the STRUCTIJRAL FILL sections of this report. Where moisture
control is critical, the slab-on-grade floors should be placed on a capillary break which is
in tum placed on the compacted subgrade. The capillary break should consist of a
minimum four-inch-thick layer of clean, free-draining, 7/8-inch crushed rock, containing
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no more than 5 percent by weight passing the No. 4 sieve. A vapor barrier, such as a 6-
mil plastic membrane, may be placed over the capillary break, as required, to keep
moisture from migrating upwards.
PAVED DRIVEWAY AND PARKING AREAS
Performance of driveway and parking area pavement is critically related to the conditions
of the underlying subgrade soils. We recommend that the subgrade soils under the
driveways be treated and prepared as described in the SITE PREPARATION AND
GENERAL EARTHWORK section of this report. Prior to placing base material, the
subgrade soils should be compacted to a non-yielding state with a vibratory roller
compactor and proof-rolled with a piece of heavy construction equipment, such as a fully-
loaded dump truck. Any areas with excessive flexing or pumping should be over-
excavated and re-compacted or replaced with a structural fill or crushed rock placed and
compacted in accordance with the recommendations provided in the STRUCTURAL
FILL section of this report. We recommend that a layer of compacted, 7/8-inch crushed
rock base (CRB), be placed for the roadway/driveways. This crushed rock base should be
at least 6 inches for the joint-use driveway and at least 4 inches for private individual
driveways. This crushed rock base should be overlain with a 3-inch asphalt treated base
(ATB) topped by a 2-inch-thick Class B asphalt concrete (AC) surficial course.
DRAINAGE CONTROL
Building Footprint Excavation
Footprint excavation for proposed townhome buildings, if encountering groundwater
seepage, should have bottom of excavation sloped slightly and ditches excavated along
bases of the cut banks to direct collected groundwater into sump pits from which water
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~be.pumped qut.. AJare( .Q(.'.?cll}Ch ~hed rock should beplared over footing bearin1s
!1:ttbgp1de :soils, aS reqµired,;td pr9tect the soils'fromdisturbance' by constructibn traffi~.
This crushed rock base sh?uld De. built to a few inches above groundwater level, but not
less than 6 inches thick. The crush rock base should be compacted in 12-inch lifts to a
lf<Xl\Yieldjn:g ·state with a .vibratory mech~cal compactor.
Runoff over Imp_ervfous Surfaces
Storm runoff over impervious surfaces, Such as roofs ·and paved driveways, should· be
9ollected by underground drain line systems COI)llected to do~pout~ and by catch basins
m.Stalled in paved driveways. Stormwater thus collected should be tightlined to discharge
into a storm se~er or suitable sto~water disposal facilities.
Building Footing Drains
A subdrain should be installed; around the perimeter footings of each townhome building.
The subdrains should consist of a 4-inch-minimum-diameter, perforated, rigid, drain pipe,
laid a few inches below bottom ·of the perimeter footings ·of the buildings. The trenches
illld the drain lines should_.have a sufficient gradient (0.5% minimum) t~ generate flow by
gravity. The drain lines should be wrapped in a non-woven filter fabric sock and
completely enclosed in clean washed gravel. The remaining trenches may be backfilled
with clean onsite soils. Water collected by the perimeter footing subdrain systems should
be tightlined, separately from the roof and surface stormwater drain lines, to discharge
into a storm sewer or suitable stormwater disposal facilities.
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Surface Drainage
Water should not be allowed to stand in any areas where footings, on-grade slabs, or
pavement is to be constructed. Finish ground surface should be graded to direct surface
runoff away from the townhome buildings. We recommend the finish ground be sloped
at a gradient of 3 percent minimum for a distance of at least IO feet away from the
buildings, except in the areas to be paved.
Cleanouts
Sufficient number of cleanouts at strategic locations should be provided for underground
drain lines. The underground drain lines should be cleaned and maintained periodically
to prevent clogging.
Detention Facility
The project site is underlain at shallow depth by a very-dense cemented lodgrnont till
deposit of extremely low permeability. Therefore, onsite stormwater disposal by
infiltration will not work well. A buried concrete detention vault or corrugated metal
detention pipe may be used to detain stormwater collected over impervious surfaces
within the project site. A detention pipe is normally more economical and is
recommended.
Detention pipe trench should be excavated down to undisturbed very-dense lodgrnont till
soil. Standing water and loose disturbed soils in the trench, if any, should be thoroughly
removed. The lodgmont till should then be covered with a 4-to-6-inch layer of compacted
5/8-inch crushed rock base on which the detention pipe is to be founded. An allowable
soil bearing pressure of 4,000 psf may be sued for the design of the detention pipe. The
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trench along the sides and over the top of the detention pipe should also be backfilled
with 5/8-inch crushed rock. The crushed rock fill should be placed in loose lifts no more
than 10 inches thick, with each lift thoroughly compacted to a non-yielding state with a
vibratory mechanical compactor. It is critical to have the crushed rock fill around the
pipe compacted to a non-yielding state to support the pipe and keep it from structural
damage due to deflection.
RISK EVALUATION STATEMENT
The subject site is underlain at shallow depth by very-dense lodgmont till deposit ofvery-
high shear strength. Therefore, the site should be quite stable. It is our opinion that if the
recommendations in this report are fully implemented and observed during and following
completion of construction, the areas disturbed by construction will be stabilized and will
remain stable, and will not increase potential for soil movement. In our opinion, the risk
for damage to the proposed development and from the development to adjacent properties
due to soil instability should be minimal.
LIMITATIONS
This report has been prepared for the specific application to this project for the exclusive
use by Mr. Kevin Su, and his associates, representatives, consultants and contractors. We
recommend that this report, in its entirety, be included in the project contract documents
for the information of the prospective contractors for their estimating and bidding
purposes and for compliance with the recommendations in this report during construction.
The conclusions and interpretations in this report, however, should not be construed as a
warranty of subsurface conditions of the site. The scope of this investigation does not
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include services related to construction safety precautions and our recommendations are
not intended to direct the contractor's methods, techniques, sequences or procedures,
except as specifically described in this report for design considerations. All geotechnical
construction work should be monitored by a geotechnical engineer during construction.
Our recommendations and conclusions are based on the geologic and soil conditions
encountered in the test pits, and our experience and engineering judgment. The
conclusions and recommendations are professional opinions derived in a manner
consistent with the level of care and skill ordinarily exercised by other members of the
profession currently practicing under similar conditions in this area. No warranty,
expressed or implied, is made.
The actual subsurface conditions of the site may vary from those encountered by the test
pits excavated on the site. The nature and extent of such variations may not become
evident until construction starts. If variations appear then, we should be retained to re-
evaluate the recommendations of this report, and to verify or modify them in writing prior
to proceeding further with the construction of the proposed development of the site.
CLOSURE
We are pleased to be of service to you on this project. Please feel free to contact us if you
have any questions regarding this report or need further consultation.
LIU & ASSOCIATES, INC.
June 20, 2015
Townhome Buildings
L&A Job No. 15-062
Page 19
Six plates attached
Yours very truly, u:z:
J. S. (Julian) Liu, Ph.D., P.E.
Consulting Geotechnical Engineer
LIU & ASSOCIATES, INC.
LIU & ASSOCIATES. INC.
VICINITY MAP
SU TOWNHOMES
16826 -108TH AVENUE SE
Geotechnical Engineering· Engineering_Geology · Earth Sci,ence l----..,s;,;,-,-,,,---,R,,E~N~T;.O.:..c.N.;-,,__W~A;.,;;S;;H...:.;;IN.,:;;G;,T;.O;:..;,N;....,~~=-----1
JOB NO. 15-062 DATE 6/18/2015 PLATE _1_
tar,
\, ti
i
.i
7
SITE AND EXPLORATION LOCATION PLAN
LIU & ASSOCIATES. INC. SU TOWNHOMES
16826-108TH AVENUE SE
Geotechnical Engineering · Engineering Geology :_Earth __ sc_-,nce 1--~J=o=s-N=o-. ~~=s~-~-J-O_N-''-~-:~TS~E H-~-~-~-,!-~-
1
~~~P-LA-T~E~---
2
=-_.
UNIFIED SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GRAVEL CLEAN
COARSE-MORE THAN 50% OF GRAVEL
GRAINED COARSE FRACTION GRAVEL WITH
SOILS RETAINED ON NO. 4 SIEVE FINES
SAND CLEAN
MORE THAN 50% MORE THAN 50% OF SAND
RETAINED ON THE COARSE FRACTION SAND WITH
NO. 200 SIEVE PASSING NO. 4 SIEVE FINES
FINE-SILT AND CLAY INORGANIC
GRAINED LIQUID LIMIT
SOILS LESS THAN 50% ORGANIC
MORE THAN 50% SILTY AND CLAY INORGANIC
PASSING ON THE LIQUID LIMIT
NO. 200 SIEVE 50% OR MORE ORGANIC
HIGHLY ORGANIC SOILS
1. FIELD CLASSIFICATION IS BASED ON VISUAL EXAMINATION
OF SOIL IN GENERAL ACCORDANCE WITH ASTM D2488-83.
2. SOIL CLASSIFICATION USING LABORATORY TESTS IS BASED
ON ASTM D2487-63.
3. DESCRIPTIONS OF SOIL DENSITY OR CONSISTENCY ARE
BASED ON INTERPRETATION OF BLOW-COUNT DATA, VISUAL
APPEARANCE OF SOILS, AND/OR TEST DATA.
LIU & ASSOCIATES, INC.
-
Geotec~~ical Engineeri.ng ·-··-Engineering Geology _-___ E_a_rt_h _scie_· _n_ce_
GROUP GROUP NAME
SYMBOL
GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL
GP POORLY-GRADED GRAVEL
GM SILTY GRAVEL
GC CLAYEY GRAVEL
SW WELL-GRADED SAND, FINE TO COARSE SAND
SP POORLY-GRADED SAND
SM SILTY SAND
SC CLAYEY SAND
ML SILT
CL CLAY
OL ORGANIC SILT, ORGANIC CLAY
MH SILT OF HIGH PLASTICITY, ELASTIC SILT
CH CLAY OF HIGH PLASTICITY, FAT CLAY
OH ORGANIC SILT, ORGANIC SILT
PT PEAT AND OTHER HIGHLY ORGANIC SOILS
SOIL MOISTURE MODIFIERS:
DRY -ABSENCE OF MOISTURE, DUSTY, DRY TO
THE TOUCH
SLIGHTLY MOIST -TRACE MOISTURE, NOT DUSTY
MOIST-DAMP, BUT NO VISIBLE WATER
VERY MOIST -VERY DAMP, MOISTURE FELT TO THE TOUCH
WET -VISIBLE FREE WATER OR SATURATED,
USUALLY SOIL IS OBTAINED FROM BELOW
WATER TABLE
UNIFIED SOIL CLASSIFICATION SYSTEM -
PLATE 3
I
I
TEST PIT NO. 1
Logged By: JSL Date: 6/1212015 Ground El. ±
Depth uses Sample w Other
ft. CLASS. Soil Descriotion No. % Test
-OL Dark-brown, loose, organic, silty fine SAND, slightly moist
1 ~-CTOP~O!U_ __________________________ --------SM Brown, rn<>dium-dense, silty fine SAND, some gravel, dry
2 -
-3 -
4 --~1,i;:,-Light-gray, very-dense, gravelly, silty, fine SAND, occasional ·---cobble, cemented, slight moist (VASHON TILL)
5 --6 --7 --a -
-9 --10
-11 Test cit terminated at 10.0 ft; aroundwater seecaae not encountered.
TEST PIT NO. 2
Logged By: JSL Date: 611212015 Ground El. ±
Depth uses Sample w Other
ft. CLASS. Soil Descriotion No. % Test
OL -Dark-brown, loose, organic, silty fine SAND, slightly moist
1 -----~ _([OPSOIL) ___ ----____________________ --SM Brown, medium-dense, silty fine SAND, some gravel, dry
2 to wet --3_
·---------------------------------------
4 -SM Light-gray, very-dense, gravelly, silty, fine SAND, occasional
---
cobble, cemented, slight moist (VASHON TILL) -5 -
-6 -
-7 -
-a -
-
9_
-10 -Test pit terminated at 9.5.0 ft; groundwater not encountered. -11
TEST PIT LOGS
LIU & ASSOCIATES. INC. SU TOWNHOMES
16826-108TH AVENUE SE
--Geotechnical Engin~ring _-Engin~~~~-~eo~~~Y · Earth Science RENTON WASHINGTON --JOB NO. 10-UOL DATE o/1.;>ILU '" PLATE 4
TEST PIT NO. 3 I
Logged By: JSL Date: 6/12/215 Ground El. ±
Depth uses Sample w Other
ft Cl.ASS. Soil Descriotion No. % Test
OL -Dark-brown, loose, organic, silty fine SAND, slightly moist
1 ~----------lIOf'$0~~--------------------------
SM Brown, medium-dense, silty fine SAND, trace to some gravel, dry
2 --
-3 -----------------------------------------4 -SM Light-gray, very-dense, gravelly, silty, fine SAND, occasional
-cobble, cemented, slightly moist (VASHON TILL)
5 -
-6_
-7 --8
9 --= Test pit terminated at 8.0 ft; groundwater not encountered.
-10
TEST PIT NO. 4
Logged By: JSL Date: 6/12/2015 Ground El. ±
Depth uses Sample w Other
ft. Cl.ASS. Soil Descriotion No. % Test
OL -Dark-brown, loose, organic, silty fine SAND, slightly moist
1 (TOPSOIL) ------~------------------------------------2 -SM Yellowish-brown, medium-dense, silty fine SAND,. trace gravel, dry
-
3 ---s;;;;-,-Light-gray, very-dense, gravelly, silty, fine SAND, occasional -
4 -cobble, cemented, slightly moist (VASHON TILL)
-5 --6 --1_
-8
-9 Test pit terminated at 8.0 ft; groundwater not encountered. --10
TEST PIT LOGS
LIU & ASSOCIATES, INC. SU TOWNHOMES
16826 -108TH AVENUE SE ------------------
Geotechnical Engineering · Engineering Geology · Earth Science RENTON, WASHINGTON .. -----------------
JOB NO. 15-062 DATE 5/13/2015 Pl.ATE 5
TEST PIT NO. 5
Logged By: JSL Date: 6/121215 Ground El. ±
Depth uses Sample w Other
ft. CLASS. Soil Description No. % Test
-OL Dark-brown, loose, organic, silty fine SAND, slightly moist
1 (TOPSOIL) -
------~----------------------------------2 -SM Rusty-brown, medium-dense, silty fine SAND, trace gravel, slightly
moist
3 ...:::
-·------Light-gray, very-dense, gravelly, silty, fine SAND, occasional 4 SM -cobble, cemented, slightly moist (VASHON TILL) -5 --6 -
-7 --8
-
9 Test pit terminated at 8.0 ft; groundwater not encountered. --10
TEST PIT NO.
Logged By: Date: Ground El. ±
Depth uses Sample w other
ft. CLASS. Soil Description No. % Test
-1 -
-2 -
-3 -
-• --
-5 -
-6_
-7 --8 --9 -
-10
TEST PIT LOGS
LIU & ASSOCIATES, INC. SU TOWNHOMES
16826 -108TH AVENUE SE
-·· ·--·------~---
Geotechnical Engineering · Engineering Geology · Earth Science RENTON, WASHINGTON ·---~----
JOB NO. 15-062 DATE 5/13/2015 PLATE 6
APPENDIXB
Drainage Plans
32
FIElO 6001<: --------I
SURVEYED·-------~
SUMY BASE YAP-----~
DESIGN [NT[RED: ______ _
DESIGNED -------~
CHECKED. _______ ----"
FLOW
A
ELEV, .11125.0
~
r-----------i ----------------------------------------,
I I
: I I ,-,~---FLOW
!
I
I
I
I
WET/DRY VAULT
38' X [g'
! __________________________________________________ _
PLAN VIEW
NTS N'JT T0 S(Alf
~
A
~
'.W/S'f'/1.,'f'J;. GROUND '1.X~'lf///1;. Y,Xif1»i1, frf>.'!fl/fiJ/'i: ?AV/!i'l//l,
~
ELEV. 425,0
ELEV =.o!3~
w.a. DESJGN
SURFACE ELEV 431.5'-
12"
6' VAULT# 2 El.ID!.
RESTRICT OR
6' SEDIMENT
p
SECTION A -A
H-20 WA'1'ER 'DETENTION VAULT
M
---------""''-"""'"'"-l'ORREF~ I
NOTES
CONCRETE 28 DAYS COMPRESSIVE STREl'fGTH li;:w4:,00 pSi
REBAR: ASlM A-615 GRADE 60
MESH: ASTM A-185 GRADE 65
DESIGN:ACl-316-02 BUILDING CODE ASTIII c.8S7 "'MIINMUM STRUCTVRE DESIGN LOADING FOR
UNDERGROUND PRECAST CONCRETE UTILITY STRUCTURE$."
LOADS:H-20 TRUCK WHEEEL Wl30'll:, IMPACT PER AASHTO
ALL METAL PARTS MUST 8E CORROSION RESISTANT. STEEL PARTS MUST BBE GALVANIZED ANO
ASPHALT COATED (TREAlMENT IOR B:TTER)
PROVIDE WATER STOP AT ALL CAST~N.PLACE COHSTRUCTION JOINTS. PRECAST VAULTS SHALL
HA.VE APPROVED RUBBER GMKET SYSTEM.
CALL 2 WORKING
DAYS BEFORE YOU DIG
1-800-424-5555
(UNO[RGROUNO UTILITY LOCATIONS ARE APPROX.)
SHEET
OF
SHEETS
CONSTRUCTION ENTRANcr:
...l..; ~r:
<
~
3
Jp"'
> '
REMOVED CONCRETE ~OVED T_!:!g SHED
/ .
I '•Ls ~sl'~'SF---SF-• i --SF--SF ' -h, I
r._,,,
7
\ ·---}LJ f i _ I ~ _ .. ~-__ _::· ~ DI --D, -~ SF-SF .,, -SF'
---. ,_ " --
; ·-·~ -. t-==-:=_JSF-:--si'-s -sj;i, "''""-w . I I " SF-S I I ---SF-SF~-::-::--:_ -
' D .,.a F~QPF-• ----, -_,,_, --. __J • SF-SF-SF -"Jo', I, SF-SF-'s;--l--sa-~SF -~F L____J
: I NB9°34'54"E
sF-sFI SF---r-sF--SF-----.p~F--:..... SF-sF-sF ~ ~;6-s~ ~f'
I I 3738' ff)
-----,;'._;,6' 434 \
0
I
432 ~
: I
-,&
0 ill ~~
~
~
', REMOVED THE SHED TEMPORARY SEDIMENT TRAP ------~
0 20 40
SCALE IN FEET
SILT FENCE
TEMPORARY DITCH
-SF-SF-SF-
EXISTING PROPERTY BOUNDARY LINE
TREE REMOVED
(SEE TREE REMOVED PLAN FOR DETAILS)
........ ...,...___.._....._
SUPv[Y ONO[ MN ______ _
_.,., ;"/ ..-------.....::·: \ . ' ' ~·t._::1e,~1 1:.·i11:.f.i1:.c-J.W
s.w
s.w
\> ____ // .. ~~.:..·' ,-
=:J GROUND LINE
2' -O" SETTLING DEPTH
1-0' SEDIMENT STORAGE
TEMPORARY SEDIMENT TRAP CROSS SECTION
NOT TO SCALE
TESC PLAN
168 DEVELOPMENT
16828 108TH AVE SE
RENTON, WA 98055
CALL 2 WORKING
DAYS BEFORE YOU DIG
1-800-424-5555
';.IILL
3
11
C-3.00
FIELD BOOK:------~
SUFM:YEO: _______ _
SURVEY BASE MAPc_· ------
DESIGN ENTERED: ______ ~
DESIGNED --------
CHECKED: _______ _
w
[/)
w > <{
r
f-a:,
0
·L===~0
s :: ~
INVERT ELEVATION=431.50'
' 0 :: E~
:1 @!
f I ;~ L
" I
' ;
~~
• ,,,-J=--d=·
"' PEOPOAWS STORM SE'NER LINE -ST -ST -
PROPOSED UNOERDRAIN
PROPOSED MANHOLE
EXISTING STORM SEWER LINE
-uo-uo-
0
DETENTION VAULT FOR ROOFS
38'X19'X6
INVERT ELEVATION:431.50'
[~"" ;;~<1
~ ~ I : I Q :
I :
g
drive way
2j50
I I . -1-----+--:::::-+I----I-== '+/"' -I
~---------=----·-------· 1-:....-----'----·--"~
DETENTION VA.ULT FOR ROADWAY
143'X B'Xl'
I I ___________ ..J
20 40
SCALE IN FEET
I :;i
g:,i ,.;J ,~
~~
~ I~ !!lw
IF1N1$ GF\ADE
it H--1-kL_I\
IU::~ '"II I \ Fr T i11ii I +-4-A=U : . . . 1 1 1
,
~t1ULT
,oo "'
11
,, ,,
~,I 1111:::ili. ... ff
I I
'" "" 280
DRAINAGE PROFII£:
' 1
,lj~ -1,,
lo=i
~
1$
I
I
t--
FRAME Gke,TE ~
l~Jr
~20
SCALE IN FEET
AXB'
\
=i
i
~
~
CALL 2 WORKING
DAYS BEFORE YOU DIG
1 -800-424-5555
--------------'-("-"-"-",o_o,_o_m_1uTY LOCATIONS AR[ APPROX.)
GRADING ELEVATIONS
AND PLAN
168 DEVELOPMENT
16828 108TH AVE SE
RENTON, WA g3055
SHEET
OF
SHEETS
BOTTOM ELEV, -12-1,I
I -----------------------------------------------------------
1
I FLOWJI!, --\I
OUTLET PIPE
1
A
!
!
WET/ORY VAULT
143' X 8' A
j
·------------------------------------------------------------------------------------· V
BOTTOM ELEV, -12-4,0
F'RAMES, GRATES
ELl1l!
RESTRICTOR
9
ELEV .424.70
PLAN VIEW
NTS
--£LEV -127,70 SURFACE
I
.D.DESIGN
M
'
2· p.s• DEAD STORAGE
s• SEDIMENT
FRAMES, GRATES
.,fii:j[.~)~~':'t:
7iifili;!J!:,
12"
VAULT#
GRADATION PLAN
BOTTOM ELEV. -12-1. 7
BOTTOM£ ELEV, -12.11,6
NOTES
CONCRETE 28 DAYS COMPRESStVE STRENGTH Jr::-4500 psi
RE6AR: ASTM A-(;15 GRADE 60
MESH:ASTM A-1BS GRADE 6S
DESIGN:ACl-318-02 BUILDING CODE ASTM C-8S7 "MIINMUM STRUCTURE DESIGN LOADING FOR
UNDERGROUND PRECAST CONCRETE UTILITY STRUCTURES."
LOAOS:1-1-20 TRUCK WHEEEL W/30% IMPACT PER AASHTO
ALL METAL PARTS MUST BE CORROSION RESISTNIT.STEEL PARTS MUST BBE GALVANIZEO AND
ASPHALT COATED {lll;EATMENT I OR BETTER!
PROVIDE WATER STOP AT ALL CAST-IN-PLACE CONSTRUCTION JOINTS. PRECAST VAULTS SHALL
HAVE APPROVED RUBBER GASKET SYSTEM
LEV =~2q.z0
ELEV, .424,70
CALL 2 WORKING
DAYS BEFORE YOU DIG
1-800-424-5555
SHEET
5
OF
5
SHEETS
C-5.00
APPENDIXC
Stormwater Modeling Report (MGSFlood Program Input and
Output)
33
Program Version: MGSFlood 4.28
Program License Number: 2002100
Run Date: 07/29/2015 10:28 AM
MGS FLOOD
PROJECT REPORT
Input File Name:
Project Name:
SR 515 108th Ave SE -1.fld
SR 515108th Ave SE -1
Analysis Title:
Comments: This detention provide detention for the Roof runoff
-----------PRECIPITATION INPUT-----------
Computational Time Step (Minutes): 60
Extended Precipitation Timeseries Selected
Climatic Region Number: 13
Full Period of Record Available used for Routing
Precipitation Station: 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097
Evaporation Station : 961040 Puget East 40 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 ***********************
-···········-········SCENARIO: PREDEVELOPED
Number of Subbasins: 1
---------· Subbasin : Subbasin 1 ----------
-------Area(Acres) --------
Till Forest
Till Pasture
Till Grass
Outwash Forest
Outwash Pasture
Outwash Grass
Wetland
Green Roof
User 2
Impervious
0.196
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Subbasin Total 0.196
···-··-·-·------SCENARIO: POSTDEVELOPED
Number of Subbasins: 1
---------Subbasin : Subbasin 1 --------
-----Area(Acres) -----
Till Forest
Till Pasture
Till Grass
Outwash Forest
Outwash Pasture
Outwash Grass
Wetland
l,rP.P.n Rnnf
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
User2
Impervious
Subbasin Total
0.000
0.196
0.196
************************* LINK DATA*******************************
----------------------SCENARIO: PREDEVELOPED
Number of Links: 0
************************* LINK DAT A *******************************
---------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
Link Name: Vault 1
Link Type: Structure
Downstream Link: None
Prismatic Pond Option Used
Pond Floor Elevation (ft)
Riser Crest Elevation (ft)
Max Pond Elevation (ft)
Storage Depth (ft)
Pond Bottom Length (ft)
100.00
106.50
6.00
38.0
19.0 Pond Bottom Width (ft)
Pond Side Slopes (ft/ft)
Bottom Area (sq-ft)
Area at Riser Crest El (sq-ft)
: L 1= 0.00
722.
722.
0.017
4,332.
0.099
(acres)
Volume at Riser Crest (cu-ft)
(ac-ft)
Area at Max Elevation (sq-ft)
(acres) :
Vol at Max Elevation (cu-ft)
(ac-ft) :
Massmann Infiltration Option Used
722.
0.017
4,765.
0.109
Hydraulic Conductivity (in/hr) 0.00
106.00
L2= 0.00 W1= 0.00 W2= 0.00
Depth to Water Table (ft)
Bio-Fouling Potential
Maintenance
: 100.00
Riser Geometry
Riser Structure Type
Riser Diameter (in)
Common Length (ft)
Riser Crest Elevation
: Low
: Average or Better
: Circular
: 18.00
: 0.000
: 106.00 ft
Hydraulic Structure Geometry
Number of Devices: 2
--Device Number
Device Type
Control Elevation (ft)
Diameter (in)
Orientation
Elbow
1 ---
Circular Orifice
100.00
0.20
: Horizontal
: No
---Device Number 2 -
Device Type : Vertical Rectangular Orifice
Control Elevation (ft) : 103.65
Length (in)
Height (in)
Orientation
Elbow
: 0.01
: 28.30
Vertical
:No
**********************FLOOD FREQUENCY AND DURATION STATISTICS*******************
--------·--·····------SCENARIO: PREDEVELOPEO
Number of Subbasins: 1
Number of Links: O
---·-·-------------SCENARIO: POSTDEVELOPED
Number of Subbasins: 1
Number of Links: 1
********** Subbasin: Subbasin 1 **********
Flood Frequency Oata(cfs)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) Flood Peak (cfs)
2-Year
5-Year
10-Year
25-Year
50-Year
100-Year
200-Year
5.456E-02
7.008E-02
7.817E-02
9.138E-02
0.102
0.115
0.121
•••••••••• Link: Vault 1 Link Inflow Frequency Stats
Flood Frequency Data(cfs)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) Flood Peak (cfs)
2-Year
5-Year
10-Year
25-Year
50-Year
100-Year
200-Year
5.456E-02
6.943E-02
7.817E-02
9.138E-02
0.102
0.115
0.121
.......... Link: Vault 1 •••••••••• Link WSEL Stats
WSEL Frequency Data(ft)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) WSEL Peak (ft)
1.05-Year
1.11-Year
1.25-Year
2.00-Year
3.33-Year
5-Year
10-Year
25-Year
50-Year
100-Year
102.142
102.343
102.744
103.494
104.152
104.614
105.190
105.555
105.823
105.934
***********Groundwater Recharge Summary*************
RF>r.h;arne is comnuted as inout to Perlnd Groundwater Plus Infiltration in Structures
Total Predeveloped Recharge During Simulation
Model Element Recharge Amount (ac-ft)
Subbasin: Subbasin 1 33.984
Total: 33.984
Total Post Developed Recharge During Simulation
Model Element Recharge Amount (ac-ft)
Subbasin: Subbasin 1 0.000
Link: Vault 1 0.000
Total: 0.000
Total Predevelopment Recharge is Greater than Post Developed
Average Recharge Per Year, (Number of Years= 158)
Predeveloped: 0.215 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
********** Link: Vault 1
Basic Wet Pond Volume (91% Exceedance): 857. cu-ft
Computed Large Wet Pond Volume, 1.S*Basic Volume: 1286. cu-ft
Infiltration/Filtration Statistics----------------
Total Runoff Volume (ac-ft): 86.56
Total Runoff Infiltrated (ac-ft): 0.00, 0.00%
Total Runoff Filtered (ac-ft): 0.00, 0.00%
Percent Treated (lnfiltrated+Filtered)/Total Volume: 0.00%
***********Compliance Point Results *************
Scenario Predeveloped Compliance Subbasin: Subbasin 1
Scenario Postdeveloped Compliance Link: Vault 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 4.161E-03 2-Year 1.995E-03
5-Year 7.102E-03 5-Year 4.391E-03
10-Year 8.838E-03 10-Year 6.664E-03
25-Year 1. 140E-02 25-Year 8.503E-03
50-Year 1.373E-02 50-Year 9.745E-03
100-Year 1.648E-02 100-Year 1.026E-02
200-Year 2.228E-02 200-Year 2.578E-02
•• Record too Short to Compute Peak Discharge for These Recurrence Intervals
**** Flow Duration Performance ****
Excursion at Predeveloped 50%02 (Must be Less Than 0%):
Maximum Excursion from 50%02 to 02 (Must be Less Than 0%):
Maximum Excursion from 02 to 050 (Must be less than 10%):
Percent Excursion from 02 to 050 (Must be less than 50%):
MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS
-8.3% PASS
-6.1% PASS
0.8% PASS
1.3% PASS
J
J II
I -u, -u -
Flow Duratiun Plot
0..0,. :f I 1 fl it.th I T 1 ti·lmf I i tl ltl/11 i 1-1 if:IIU. I f t:tlrfli t I 1 IHiff ·1 :i I ;fl dil
om
1· Flow Control Performance
-~~~~;-~·~'!.~~ I Iii•
ExOUf'i.ion :50%02 to Q2: ~-1% PASS
•• 040U& • • •• ..... • • • ....... • :[ I ·1· .~~~~.9-"1:_o,.~.~~ t •· .•.
·I 11111111 111111111 111111111 I %PosExcutsioo02toO..~: 1 . .3~PASS : ~ ·; t I ltl·l llil I ~ I:~: 11,1,11 1 1 1 1 •,11u 1 ·• 1 " 1 w.,
ii: I Iii
,, 11,,
ii
~ om
lL ii 11 ll lllr ii, i
. m n. . .., HH 1111 lill
Q5G
-•-._. ,.n1.11--t,. 4-ol HI lllf--I +-11 HIHT --I -1-1-1-IMII. --1-
1!
•• • • • •m•••""' • ,• • !
I
ii
/1-lJ~ltc-
Mm ! ,0:•
i~~,02 '-ItlUlt:: -.. : I . :.O%Q2 -"i
tQ!,,,01 1 .Cl!-<l!i 1.0@,,(15 tO!-Oi 1.0Mll 1.Qe.Q2 , .0!-0, 1-0!+00
Exceeda.nce Probabltlty
/ Predeve toped / Postdevel oped
fR-inht rlir:k ~ r ~r.h t.-. ~ nM
Program Version: MGSFlood 4.28
Program License Number: 2002100
Run Date: 07/22/2015 12:51 PM
MGS FLOOD
PROJECT REPORT
Input File Name:
Project Name:
Analysis Title:
SR 515 108th Ave SE-2.fld
"R 515 108th Ave SE· 2
Comments:
-----------PRECIPITATION INPUT-----------
Computational.Time Step (Minutes): 60
Extended Precipitation Timeseries Selected
Climatic Region Number: 13
Full Period of Record Available used for Routing
Precipitation Station: 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097
Evaporation Station 961040 Puget East 40 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**'*********************
·····-······-·-····SCENARIO: PREDEVELOPED
Number of Subbasins: 1
-----····· Subbasin : Subbasin 2 -·-·-·-
Till Forest
Till Pasture
Till Grass
Outwash Forest
Outwash Pasture
Outwash Grass
Wetland
Green Roof
User2
Impervious
-----Area(Acres) ·····-·
0.475
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.079
Subbasin Total 0.554
----------------------SCENARIO: POSTDEVELOPED
Number of Subbasins: 1
---------Subbasin : Subbasin 2 ----------
Till Forest
Till Pasture
Till Grass
Outwash Forest
Outwash Pasture
Outwash Grass
Wetland
Green Roof
User2
Impervious
Subbasin Total
------Area(Acres) ------
0.000
0.000
0.304
0.000
0.000
0.000
0.000
0.000
0.000
0.250
0.554
************************* LINK DAT A *******************************
-------------------SCENARIO: PREDEVELOPED
Number of Links: 0
************************* LINK DAT A *******,.,***********************
------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
Link Name: Vault 2
Link Type: Structure
Downstream Link: None
Prismatic Pond Option Used
Pond Floor Elevation (ft)
Riser Crest Elevation (ft)
Max Pond Elevation (ft)
Storage Depth (ft)
Pond Bottom Length (ft)
Pond Bottom Width (ft)
Pond Side Slopes (ft/ft)
Bottom Area (sq-ft)
Area at Riser Crest El (sq-ft)
(acres)
Volume at Riser Crest (cu-ft)
(ac-ft)
Area at Max Elevation (sq-ft)
(acres)
Vol at Max Elevation (cu-ft)
(ac-ft)
100.00
103.50
3.00
142.0
8.0
: L1= 0.00
1136.
1,136.
0.026
3,408.
0.078
1136.
0.026
4,090.
0.094
103.00
L2= 0.00 W1 = 0.00 W2= 0.00
Massmann Infiltration Option Used
Hydraulic Conductivity (in/hr) 0.00
Depth to Water Table (ft) : 100.00
Bio-Fouling Potential : Low
Maintenance : Average or Better
Riser Geometry
Riser Structure Type
Riser Diameter (in)
Common Length (ft)
Riser Crest Elevation
Hydraulic Structure Geometry
Number of Devices: 2
1---
· Circular
: 18.00
: 0.000
: 103.00 ft
---Device Number
Device Type
Control Elevation (ft)
Diameter (in)
Orientation
Circular Orifice
100.00
0.67
Elbow
: Horizontal
: No
---Device Number 2 ---
Device Type : Vertical Rectangular Orifice
Control Elevation (ft) 101.30
Length (in) 0.05
Height (in) 20.50
Orientation : Vertical
Elbow : No
••••••••••••**********FLOOD FREQUENCY AND DURATION STATISTICS**•••••••••********
------------------SCENARIO: PREDEVELOPED
Number of Subbasins: 1
Number of Links: 0
----------------SCENARIO: POSTDEVELOPED
Number of SLibbasins: 1
Number of Links: 1
********** Subbasin: Subbasin 2 **********
Flood Frequency Data(cfs)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) Flood Peak (cfs)
2-Year
5-Year
10-Year
25-Year
50-Year
100-Year
8.620EC02
0.112
0.135
0.177
0.197
0.206
200-Year 0.253
•••••••••• Link: Vault 2
Frequency Stats
Flood Frequency Data(cfs)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) Flood Peak (cfs)
2-Year
5-Year
10-Year
25-Year
50-Year
100-Year
200-Year
8.620E-02
0.112
0.135
0.177
0.197
0.206
0.253
********** Link: Vault 2
WSEL Frequency Data(ft)
(Recurrence Interval Computed Using Gringorten Plotting Position)
Tr (yrs) WSEL Peak (ft)
1.05-Year
1.11-Year
1.25-Year
2.00-Year
3.33-Year
5-Year
10-Year
25-Year
50-Year
100-Year
100.717
100.845
100.970
101.335
101.608
101.858
102.213
102.612
102.862
102.918
***********Groundwater Recharge Summary *************
Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Siructures
Total Predeveloped Recharge During Simulation
Model Element Recharge Amount (ac-ft)
Subbasin: Subbasin 2 82.359
Total: 82.359
Total Post Developed Recharge During Simulation
Model Element Recharge Amount (ac-ft)
Subbasin: Subbasin 2
Link: Vault 2
Total:
37.368
0.000
37.368
Link Inflow
Link WSEL Stats
Total Predevelopment Recharge is Greater than Post Developed
Average Recharge Per Year, (Number of Years= 158)
Predeveloped: 0.521 ac-ft/year, Post Developed: 0.237 ac-ft/year
***********Water Quality Facility Data*************
-------------------SCENARIO: PREDEVELOPED
Number of Links: 0
------------------SCENARIO: POSTDEVELOPED
Number of Links: 1
********** Link: Vault 2
Basic Wet Pond Volume (91% Exceedance): 1468. cu-ft
Computed Large Wet Pond Volume, 1.5*Basic Volume: 2203. cu-ft
Infiltration/Filtration Statistics--------------
Total Runoff Volume (ac-ft): 171.19
Total Runoff Infiltrated (ac-ft): 0.00, 0.00%
Total Runoff Filtered (ac-ft): 0.00, 0.00%
Percent Treated (lnfiltrated+Filtered)/Total Volume: 0.00%
***********Compliance Point Results*************
Scenario Predeveloped Compliance Subbasin: Subbasin 2
Scenario Postdeveloped Compliance Link: Vault 2
••• 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 2.708E-02 2-Year 1.371 E-02
5-Year 3.888E-02 5-Year 2.110E-02
10-Year 4.690E-02 10-Year 2.806E-02
25-Year 5.849E-02 25-Year 4.030E-02
50-Year 6.486E-02 50-Year 4.331 E-02
100-Year 7.669E-02 100-Year 4.481E-02
200-Year 9.965E-02 200-Year 7.101E-02
•• Record too Short to Compute Peak Discharge for These Recurrence Intervals
•••• Flow Duration Performance ••••
Excursion at Predeveloped 50%02 (Must be Less Than 0%): -5.8% PASS
Maximum Excursion from 50%02 to 02 (Must be Less Than 0%): -5.1% PASS
Maximum Excursion from 02 to 050 (Must be less than 10%): -3.6% PASS
Percent Excursion from 02 to 050 (Must be less than 50%): 0.0% PASS
MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS
-en
"-0 .........
_.ii ~
..2
LL
0.1S
o.,o
-
0.05
-
......
O..O'J
1.0i-(17
Flow Duratit .1 Plot
'' ·-' ·, ,.,,,, .. ' '' ,,.,-... ' ' .
Flow Control Performance ,, .~~~~~~t~~~:.-~·rf~.~~ I '
Excur$ion 50%02 to 02: -5.1~ PASS
:~~~~;o~ ~~~~~:: +~:~~:~~ 111
., % Pos Excurs;on 02 ~o C-50: O.Q6k PASS
l ,] :
i '
:~ ·I
I
i
L -~ I .. -----' --,.. . .. ----o~.c
I
' ..
~""' ,-. I I
I.
i ~ ,,
~ ' ----->-. Iii~ • t------.-02
. ~ -·---.. -. .. ~ ... --r-r-1• . r, •• 1-r,
;,O%Q2
~ .: ' -r, II BIii;:: •
1.0iKJ!;i 1 ClrOS 1.0HI£ 1,0HlJ 1 Cle-02 1 Qi--01 1 Oi'+OO
Exceedance Probability
/ Predevetoped / Postdeveloped
11Riohl: Click Graoh to Ed~l
APPENDIXD
Declaration of Covenant for Maintenance and Inspection of Flow
Control BMPs
34