HomeMy WebLinkAboutRS_Ravi Short Plat_TIR_220816_v1.pdfTECHNICAL INFORMATION REPORT
FOR
RAVI SHORT PLAT
CLIENT:
SAAA Ventures, LLC
6463—167t�T LN. SE
Bellevue, WA 98006
Phone: (425) 208-5337
PREPARED BY:
Daley-Moi7ow-Poblete, Inc.
726 Aubui7i Way North
Auburn, WA 98002
Phone: (253) 333-2200
PROJECT No. 21-390
DATE: July 11, 2022
STAMP NOT VALID UNLESS SIGNED &DATED
TABLE VV CONTENTS
DESCRIPTION PAGE
SECTION I —PROJECT OVERVIEW
Project Overview 1
Figure 1 — TIR Worksheet 2 - 6
Figure 2 — Vicinity Map 7
Figure 3 — Basin Map 8
Figure 4 — Soils Map 9 - 10
SECTION II —CONDITIONS AND REQUIREMENTS SUMMARY
Core Requirements 1 - 2
SECTION III —OFF-SITE ANALYSIS
Off -Site Analysis 1 - 18
SECTION N —FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID
AND WATER QUALITY FACILITY ANALYSIS AND DESIGN
Existing Site Hydrology 1
Developed Site hydrology I
Performance Standards 1
Flow Control System 1
Water Quality System 1
Developed Condition Basin Map 2
Upstream Basin Map 3
Hydrologic Modeling 4 — 15
R-Tank Brochure 16 - 20
SECTION V —CONVEYANCE SYSTEM ANALYSIS AND DESIGN
Conveyance System Design To be added
SECTION VI —SPECIAL REPORTS AND STUDIES
Geotechnical Engineering Study, dated Nov. 2, 2021
SECTION VII —OTHER PERMITS N/A
SECTION VIII — C.S.W.P.P.P. ANALYSIS AND DESIGN To be added
SECTION IX —BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF
COVENANT
Bond Quantities Worksheet To be added
Storm Facility Summary Sheet N/A
Declaration of Covenant To be added
SECTION X —OPERATIONS AND MAINTENANCE MANUAL
Operation and Maintenance 1 - 8
SECTION I
PROJECT OVERVIEW
PROJECT OVERVIEW
Tax parcel 142305-9033 is within the northwest quarter of Section 14, Township 23 North,
Range 5 East, Willamette Meridian, City of Renton, King County, Washington. The property
has direct frontage along SE 2nd Place along its southern border. The property is approximately
180 feet west of the intersection of SE 2nd Place and 156"' Avenue SE. The site address is 6304
SE 2nd Place.
The approximately 1-acre property is zoned R-4. The rectangular -shaped project site is
developed with a single-family home, detached garage and landscaping. The site is a part of the
Lower Cedar drainage basin. The site has moderate slope and drains to the southwest. Site soils
are classified by the USDA Soils Conservation Service as Alderwood gravelly sandy loam
(AgC).
It is proposed to subdivide the property into 3sfngle-family residential lots. Roadway
improvements are being proposed for SE 2" d Place along the site frontage. The existing house
will remain in Lot 1, while the existing garage will remain on Lot 2 and will be converted to an
ADU. The private driveways totaling approximately 1,650 sq,ft, will be permeable pavement,
and will require no further treatment. Untreated pavement within SE 2" d Place, with an area of
766 sq.ft. will be created. Since the untreated PGIS is less than 5,000 sq.ft., we believe this area
is exempt from Core Requirement #8. Splash blocks will be provided for the back half of the
proposed houses Soil amendment will also be used.
To mitigate for the increase in runoff due to development, an R-Tank underground detention
facility will be installed in Lot 1, and will be privately maintain. Due to topography, runoff from
the improvements along SE 2nd Place will bypass the proposed detention facility. To compensate
for the bypass area, it is proposed to collect runoff from the existing impervious surfaces and
some landscaped areas within Lot 1. The mitigation trade area will have the same size as the
bypass area, but will have more impervious surfaces.
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
ProjectOwner
Y
Address
_ J 01670
Part. 3 TYPE OF .PERMIT APPLICATION
Fa
Land use (e.g.,Subdivision Short Subd / UPD)
❑ Building (e.g.,M/F / Commercial / SFR)
❑ Clearing and Grading
❑ Right -of -Way Use
❑ Other
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Name XA ys/,/a/?r 1*om
DLS-Permitting
Permit #
Location Township
Z. 3N
Range
Section /
Site Address C30J EC 2 19al 10
Part 4 OTHER REVIEWS AND PERMITS
❑ DFW HPA ❑ Shoreline
❑ COE CWA 404 Management
❑ ECY Dam Safety ❑ Structural
Rockery/Vault/
❑ FEMA Floodplain
❑ ESA Section 7
❑ COE Wetlands
❑ Other.
Part 5 PLAN AND REPORT INFORMATION
Technical Information;"
nformation eport
Site Improvement
Plan
(Engr. Plans)
Full
Type of Drainage Review
❑ Targeted
Plan Type (check
`"'
❑
' ull
(check one):
❑ Simplified
one):
Modified
❑ Large Project
❑
Simplified
Date include revision
dates):
❑ Directed
✓�j�
Date include revision
dates):
Date of Final:
Date of Final:
Part 6 SWDM ADJUSTMENT APPROVALS
Type (circle one): Standard / Experimental / Blanket
Description: (include conditions in TIR Section 2)
Approved Adjustment No.
Date of Approval:
DFW:
WA
State
Dept.
of Fish and
Wildlife. HPA: hydraulic project approval. COE: (Army) Corps
of Engineers. CWA: Clean
Water
Act.
ECY:
WA
State Dept.
of Ecology. FEMA: Federal Emergency Management Agency.
ESA: Endangered Species Act.
2021 Surface Water Design Mamiat Last revised 7/23/2021
1 E`
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) VVUK 6HEET
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes No
Start Date:
Completion Date:
Describe:
Re: KCSWDM Adjustment No.
Part 8 SITE COMMUNITY AND DRAINAGE BASIN '�
Community Plan :�Gfie ��
Special District Overlays: 120Alr7:
Drainage Basin: Z19L4l1 A C�dA A R �V
Stormwater Requirements: Z D 2 / /<1C 9 y/�14*1
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
❑ River/Stream
❑
Lake _
❑ Wetlands
❑ Closed Depression
❑ Floodplain
❑ Other
❑
Steep Slope
❑ Erosion Hazard
❑ Landslide Hazard
❑ Coal Mine Hazard
❑ Seismic Hazard
❑ Habitat Protection
Part 10 SOILS ;�
Soil Type
�
9
❑ High Groundwater Table (within 5 feet) ❑Sole Source Aquifer
❑ Other ❑ Seeps/Springs
❑ Additional Sheets Attached
Erosion Potential
2021 Surface Water Design Manual Last revised 7/23/2021
2
DING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) V1/ORKSHEET
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE
❑ Core 2 — Offsite Analysis
❑ Sensve/Crcal Areas
❑ SEPA
❑ LID Infeasibility
❑ Other
❑ Additional Sheets Attached
Part 12 TIR SUMMARY SHEET
{provide one TIR Summary Sheet per Threshold Discharge Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply):
Discharge at Natural Location
Number of Natural Discharge Locations:
Offsite Analysis
Level: 12 / 3 dated: 410RIL
Flow Control (include facility
Level: 1 / 3 or Exemption Number"('
summary sheet)
Flow Control BMPs ' ANe&- A . ` -W ?C
Conveyance System
Spill containment located at:
Erosion and Sediment Control /
CSWPP/CESCUESC Site Supervisor: _TO 94; % /L/ael
Construction Stormwater
Contact Phone: �/Z /bk %D (fOA)STAX
Pollution Prevention
After Hours Phone:
Maintenance and Operation
Responsibility (circle one): Private / Public
If Private, Maintenance Log Required: Yes / D
Financial Guarantees and
Provided: Yes / No TO .9 C %o 0 V1 46FZ7 I
Liability
)�?Cq t /le O
Water Quality (include facility
Type (circle one): Basic ! Sens. Lake ! Enhanced Basic / Bog
summary sheet)
or Exemption No.
Landscape Management Plan: Yes / No
For Entire Project:
Total Replaced Impervious surfaces on the site
% of Target Impervious that had a
Total New Pervious Surfaces on the site O, /
feasible FCBMP j
Repl. Imp. on site mitigated w/flow control facility. 0
implemented
Repl. Imp, on site mitigated w/water quality facility 0
Repl. Imp. on site mitigated with FCBMP ®, 3
2021 Snrfacc Water Design Manual Last revised 7/23/2021
3
DING COUNTY, WASIIINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 12 TIR SUMMARY SHEET
(provide one TIR Summary Sheet per Threshold Discharge Area)
Special Requirements (as applicable):
Area Specific Drainage
Type: CDA / SDO / MDP / BP / LMP / Shared Fac, one
Requirements
Name:
Flood plain/Floodway Delineation
Type (circle one): Major / Minor / Exemption / None
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities
Describe:
Source Control
Describe land use:
(commercial / industrial land use)
Describe any structural controls:
Oil Control
High -use Site: Yes / No
Treatment BMP: IZVA
Maintenance Agreement: Yes / No
with whom?
Other Drainage Structures
Describe:
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
MINIMUM ESC REQUIREMENTS
CONSTRUCTION
AFTER CONSTRUCTION
TYDURING
earing Limits
abilize exposed surfaces
�
C. ver Measures
move and restore Temporary ESC Facilities
P rimeter Protection
Clean and remove all silt and debris, ensure
® ffic Area Stabilization
operation of Permanent Facilities, restore
❑ Sediment Retention
operation of Flow Control BMP Facilities as
necessary
❑ Surface Water Collection
❑ Flag limits of SAO and open space preservation
❑ nowatering Control
areas
aDust Control
❑ Other
ow Control
protection of Flow Control BMP Facilities
existing and proposed)
Maintain BMPs / Manage Project
2021 Surface Waier Design Manual Last revised 7/23/2021
a
KING COUNTY, WASHINGTON. SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch)
low Control
Type/Description
Water Quality
Type/Description
Ld Detention
❑ Vegetated Flowpath
❑ Infiltration
❑ Wet pool
❑ Regional Facility
❑ Filtration
❑ Shared Facility
,�/
t� Flow Control BMPs
❑ Other
ddd
❑ Oil Control
❑ Spill Control
Q Flow Control BMPs
❑ Other
, .4I/ ,t •
Part 15 EASEMENTS/TRACTS
Part 16 STRUCTURAL ANALYSIS
❑ Drainage Easement
❑ Cast in Place Vault
Covenant
❑ Retaining Wall
Growth Protection Covenant
❑ Rockery > 4' High
Yative
Tract
❑ Structural on Steep Slope
❑ Other
❑ 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 Info mation Report. To the best of y
knowledge the information provided here is accurate.
2021 Surface Water Design Manual
5
Last revised 7/23/2021
0
King County Map
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subject to change without notice. King County makes no representations or vianamies, express or implied, /F a
as to accuracy, completeness, tinel'ness, or rights to the use of suchinfonnatim. This ducumentis not intended Q N
for use as a survey product. Nng County shall not be liable for any general, special, indirect, incidental, or v / c/ N/ T Y MAP
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con sequential damages indud ing, but not Iinited to, lost revenues or lost profis resulting from the use or misuse
of the information contained onthis map. Any sale of this map orinfonnatim on this map is prohilIted except by
vmten permission of King County. King County
Date: 3/21 /2022 Notes:
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Soil Map —King County Area, Washington
SOILS MAP
Map Unit Legend
Map Unit Symbol Map Unit Name
Acres in AOI
Percent of AOI
AgC Alderwood gravelly sandy
loam, 8 to 15 percent slopes
1.3
100.0%
Totals for Area of Interest
1.3
10000%
USDA Natural Resources Web Soil Survey 3/21/2022
Conservation Service National Cooperative Soil Survey Page 3 of 3
CONDITIONS AND REQUIREMENTS
SUMMARY
CORE REQUIREMENT #1: DISCHARGE Al THE NATURAL LOCATION
Site runoff will continue to drain to its natural location.
CORE REQUIREMENT #2: OFFSITE ANALYSIS
See Section III.
CORE REQUIREMENT #3: FLOW CONTROL FACILITIES
An underground R-Tank detention facility will be provide to mitigate for the increase in runoff
due to development See Section IV.
CORE REQUIREMENT #4: CONVEYANCE SYSTEM
The conveyance facilities will be sized during the engineering phase, and will be added to this
report.
CORE REQUIREMENT #5: CONSTRUCTION STORMWATER POLLUTION
PREVENTION
The SWPPP will be added during the engineering phase.
CORE REQUIREMENT #6: MAINTENANCE AND OPERATIONS
On -site facilities will be privately maintained. See Section X.
CORE REQUIREMENT #7: FINANCIAL GUARANTEES AND LIABILITY
Will be provided if required by the City.
CORE REQUIREMENT #8: WATER QUALITY
Less than 5,000 sq.ft. of pollution generating impervious surface will be untreated. Therefore,
this project is exempt from this requirement.
CORE REQUIREMENT #9: FLOW CONTROL BMPs
The following BMPs were considered:
Full Dispersion —Due to the size of the lots, this option is not feasible.
Full Infiltration —Per Geotechnical Engineering Study by Earth Solutions NW, LLC in Section
VI, full infiltration is not feasible.
Limited Infiltration — This option is not feasible because any infiltration trench installed in the
available areas will be too deep in order to pick up roof runoff, and will not meet the separation
requirements.
Bioretention — Due to the size of the lots, this BMP is not feasible. Any bioretention installed in
the available areas will be too deep, and will not meet separation requirements.
Permeable Pavement —Per Geotechnical Engineering Study, limited infiltration in the upper
weathered soil horizon is feasible. Permeable pavement will be used for the individual
driveways.
Basic Dispersion —The northern half of the proposed roofs will be provided with splash blocks
to disperse runoff. There is no sufficient flowpath to disperse runoff from the southern half of
the proposed roofs. Splash blocks may be used for the southern half of the roofs, however, the
area will not be credited as being mitigated.
Per Section C.1.3.1., for a lot greater than 11,000 sq.ft., it is required to provide BMPs to 20% of
the lot area. The BMP requirement will be met as follows:
LOT 2 LOT 3
Lot Area 11,020 sq.ft. 11,021 sq.ft.
Required Mitigation Area (Lot Area x 0.20) 2,204 sq.ft. 2,204.2 sq.ft.
Half of Roof Mitigated by Basic Dispersion 1,670 sq.ft. 1,670 sq.ft.
Permeable Pavement 825 sq.ft. 825 sq.ft.
Total Area Mitigated 2,495 sq.ft.> 2,204 2,495 sq.ft. > 2,204.2
SPECIAL REQUIREMENT #1: OTHER ADOPTED AREA -SPECIFIC
REQUIREMENTS.
N/A
SPECIAL REQUIREMENT #2: FLOOD HAZARD AREA DELINEATION
N/A
SPECIAL REQUIREMENT #3: FLOOD PROTECTION FACILITIES
N/A
SPECIAL REQUIREMENT #4: SOURCE CONTROL
N/A
SPECIAL REQUIREMENT #5: OIL CONTROL
This project is not a "High Use Site"
SECTION III
OFF -SITE ANALYSIS
TABLE OF CONTENTS
Page
TASK 1: Study Area Definition and Maps
General Information 3
On -Site Drainage Analysis 3
Upstream Drainage Analysis 3
Downstream Drainage System Description 34
Future Site Conditions 4
TASK 2: Resource Review
1. Drainage Area Map 5
2. Flood Plain/Floodway (FEMA) Maps 5
3. City of Kent Surface Water Design Manual 5
4. USDA Natural Resources Conservation Service 5
Web Soil Survey
5. Drainage Investigation Information 5
TASK 3: Field Inspection
1. Investigation of Reported or Observed Problems During 6
Resource Review
2. Location of Existing/Potential Constrictions or Lack of
Capacity in the Existing Drainage System 6
3. Identify Existing/Potential Flooding Problems 6
4. Identify Existing/Potential Overtopping, Scouring, Bank
Sloughing, or Sedimentation 6
5. Identification of Significant Destruction of Aquatic
Habitat or Organisms 6
6. Collect Qualitative Data on Land Use, Impervious
Surfaces, Topography and Soil Types 6
7. Collect Information on Pipe Sizes, Channel 6
Characteristics and Drainage Structures
8. Verify Tributary Basins Delineated in Task 1 6
9. Contact Neighboring Property Owners in the Area 7
10. Note the Date and Weather Conditions at the Time of 7
Site Visits
TASK 4: Drainage System Description and Problem Description
1. Drainage System Descriptions 8
2. Problems 8
TASK 5: Mitigation of Existing or Potential Problems 9
Page 1
APPENDIX
Exhibit A Vicinity Map
Exhibit B Developed Site Plan with Pre -developed Contours
Exhibit C Drainage Basin Map
Exhibit D Downstream System Map
Exhibit E Off -Site Analysis Drainage System Table
Exhibit F Flood Plain/Floodway (FEMA) Map
Exhibit G Assessors Map
Exhibit H City of Renton COR Map
Exhibit 1 King County Soils Survey Map
Page 2
TASK I Study Area Definition and Maps
General Information
Tax parcel 142305-9033 is wn the northwest quarter of Section 14, Township 23
North, Range 5 East, Willamette Meridian, City of Renton, King County, Washington.
The property has direct frontage along SE 2nd Place along its southern border. The
project site is approximately 180 feet west of the intersection of SE 2nd Place and 156tn
Avenue SE. The site address is 6304 SE 2nd Place.
The approximately 1-acre property is zoned R-4. The rectangular -shaped project site is
developed with a single-family home, detached garage and landscaping. The site is a
part of the Lower Cedar drainage basin. The site has moderate slope and drains to the
southwest. Site soils are classified by the USDA Soils Conservation Service as
Alderwood gravelly sandy loam (AgC).
It is proposed to subdivide the property into 3single-family residential lots. The existing
house will remain in the proposed Lot 1, while the existing garage will remain in Lot 2.
Roadway improvements are being proposed for SE 2nd Place along the site frontage.
On -Site Drainage Analysis
As previously mentioned, runoff from the site drains to the southwest corner.
Upstream Drainage Analysis
Approximately 0.39 acre of mostly yard areas contributes runoff through the site.
Upstream runoff enters the site via sheet flow along the north and east property lines.
See Exhibit C for a visual illustration of this drainage basin.
Downstream Drainage System Description
As previously mentioned, runoff from the site drains to the southwest corner of the site.
Water then enters a catch a basin where a 12" pipe conveys runoff to the west for 67
feet where it discharges into a roadside ditch. The ditch flows west for 117 feet before
reaching a 29-foot long 12" driveway culvert. Upon leaving the culvert, water will travel
84 feet west within a roadside ditch. Water then continue west within a series of 12"
culvert for a total distance of 332 feet. Water then travels west within two 18" pipe for a
total distance of 258 feet to the intersection of SE 2nd Place and Rosario Avenue SE.
Water the enter a 54400t 24" pipe that convey water to the south and into a stream
within the Maple Wood Park. Water will travel approximately1,320 feet in a
southwesterly direct before entering a conveyance system at the 148t" Place SE. Water
will then travel south more than 1 mile where it drains into The Cedar River.
See Exhibit D for a visual of illustration of the drainage course and downstream system,
and Exhibit E for the Off -Site Analysis Drainage System Table.
Future Site Conditions
As previously mentioned, this project will create 3 single-family residential lots. The
existing house and garage will remain. A new access road, storm drainage facilities,
and other utilities will be provided to service the lots.
Page 4
TASK 2: Resource Review
The following is a description of each of the resources reviewed in preparation of this
Downstream Analysis:
1. Drainage Area Map
The project is located within the Lower Cedar River drainage basin.
2. Flood Plain/Floodway (FEMA) Map
Per FEMA map, there is no flood hazard on or adjacent to the site. Refer to
Exhibit F.
3. City of Renton COR Maps
A review of the City of Renton COR map reveals that there are no critical areas
on or adjacent to the site. Per Exhibit H, there are small areas between 15 to
25%. However, they are insignificant and are not considered critical.
4. USDA Natural Resources Conservation Service Web Soil Su
The soil underlying the site is Alderwood gravelly sandy loam (AgC). The King
County Soils Survey Map is included in Exhibit I.
5. Drainage Investigation Information
The reports and as-builts for the surrounding developments were review as part
oI this analysis
Page 5
TASK 3: Field Inspection
1. Investigation of Reported or Observed Problems Dunnq Resource Review
No ongoing drainage problems were identified in the review.
2. Location of Existing/Potential Constrictions or Lack of Capacity in the Existing
Drainage System
At the time of the site visit, there did not appear to be any evidence of lack of
capacity or problems within the existing drainage system.
3. Identify Existing/Potential Flooding Problems
At the time of the site visit, there did not appear to be any existing or potential
flooding problems.
4. Identify Existing/Potential Overtopping, Scouring, Bank Sloughing, or
Sedimentation
There appeared to be no evidence of overtopping, scouring or bank scouring on
the site or downstream.
5. Identification of Significant Destruction of Aquatic Habitat or Organisms
At the time of the site visit, there did not appear to be any signs of aquatic habitat
or organism destruction.
6. Collect Qualitative Data on Land Use, Impervious Surfaces, Topography and Soil
Types
Qualitative data has been collected from field visit. The information is included
within this report.
7. Collect Information on Pipe Sizes, Channel Characteristics and Drainage
Structures
See Exhibits D and E for this information.
8. Verify Tributary Basins Delineated in Task 1
The tributary basins delineated in this report were verified during the site visit.
Page 6
9. Contact Neighboring Property Owners in the Area
No homeowners were contacted during the field reconnaissance for this analysis.
10. Note the Date and Weather Conditions at the Time of the Site Visit
The site and downstream system was visited on March 22, 2022. Weather was
sunny.
Page 7
TASK 4: Drainage System Description and Problem Description
1. Drainage System Descriptions:
See Exhibit C and D for a visual of illustration of this drainage course, and Exhibit
E for the Off -Site Analysis Drainage System Table.
2. Problems:
There was no evidence of existing or future problems within the two downstream
drainage courses.
TASK 5: Mitigation of Existing or Potential Problems
This level 1 analysis has provided a complete review of the downstream conditions.
With the implementation of storm drainage facilities, the project should not pose
significant negative impacts to the downstream drainage course or drainage properties.
Page 9
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s�hject to dlange wdhout notice. Kng County makes no representafons or warranties, express or impfed,
as to accuracy, completeness, fcnelhess, or rghls to the use of suchinfonnation. Ttis nc�umentis rot intended
br use as a survey product IGng County shdl ro[ 6e leble fo' any general, special, hdimd, inddenta� or
consequentialdamages indude�g, but nd lirrited to, pst revenues or bst profii; resuking from the use or misuse
d the information contai nod on this map. My sale of the map or!nformation on this map is prohitited except by
writen permission of King County.
Date:3123/2022 Notes:
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Information Technology - GIS This map is a user generated static output from an Internet mapping site and
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256 0 128 256 Feet RentonMapSupport@Rentonwa.gov accurate, current, or otherwise reliable.
WGS_1984_Web_Mercator_Auxiliary_Sphere 03/21/2022 THIS MAP IS NOT TO BE USED FOR NAVIGATION
Legend
City and County Labels
Addresses
Parcels
City and County Boundary
<all other values>
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Renton
Network Structures
Access Riser
® inlet
Manhole
Utility Vault
Clean Out
Unknown
Control Structure
Pump Station
Discharge Point
Water Quality
Detention Facilities
Pond
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_'E_�"_--_3 Vault
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V� Wetland
Other
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Virtual Drainline
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Finance & IT Division
3/23/2022
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SECTION IV
FLOW CONTROL AND WATER
QUALITY FACILITY ANALYSIS AND
DESIGN
EXISTING SITE HYDROLOGY (PART A)
The site is part of the Lower Cedar River drainage basin. Runoff from the site is directed to the
southwest corner and into the drainage facilities within SE 2" d Place.
DEVELOPED SITE HYDROLOGY (PART B)
Runoff from the northern half of the proposed roofs will be dispersed via splash blocks
Permeable pavement will be used for the proposed driveways. A detention facility will be
provided to mitigate for the increase in runoff due to development. Any water that leaves the site
will continue to drain to its natural drainage course.
PERFORMANCE STANDARDS (PART C)
The 2022 City of Renton Surface Water Design Manual was used.
FLOW CONTROL SYSTEM (PART D)
As previously mentioned, permeable pavement will be used for the private driveways. Basic
dispersion via splash blocks will be used for half of the roof runoff. Soil amendment will also be
used. However, no credits were taken in the modeling.
Due to topography, runoff from the improvements along SE 2nd Place will bypass the proposed
detention facility. To compensate for the bypass area, it is proposed to collect runoff from the
existing impervious surfaces and some landscaped areas within Lot 1. The mitigation trade area
will have the same size (in acres) as the bypass area, but will have more impervious surfaces.
The areas are broken down as follows:
BYPASS AREA MITIGATION TRADE AREA
Sidewalk, curb, gutter, driveways 2,746 sq.ft. 0
Existing houseroof 0 25200 sq.ft.
Existing garage roof
0
0
2,239 sq.ft
4,985sq.ft. = 0.11 ac
The sizing calculation can be found in the following pages.
WATER QUALITY SYSTEM (PART E)
1,100 sq.ft.
Private driveways will be permeable pavement, and will require no additional treatment.
Untreated pavement within the R.O.W., with an area of 766 sq.ft., will be created. Since the area
is less than 5,000 sq.ft., said area is exempt from this requirement.
•
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2. PAS/ . r ra °m I MA o u x,
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OI
WWHM2012
PROJECT REPORT
Project Name: RAVI
Site Name: RAVI SHORT PLAT
Site Address: 6304 SE 2ND PL.
City : RENTON
Report Date: 7/18/2022
Gage : Seatac
Data Start : 1948/10/01
Data End : 2009/09/30
Precip Scale: 1.17
Version Date: 2021/08/18
Version : 4.2.18
Low Flow Threshold for POC 1 50 Percent of the 2 Year
High Flow Threshold for POC 1: 50 year
PREDEVELOPED LAND USE
Name SITE
Bypass: No
Groundwater: No
Pervious Land Use acre
C, Forest, Mod .596
Pervious Total 0.596
Impervious Land Use acre
Impervious Total 0
Basin Total 0.596
Element Flows To:
Surface Interflow
Groundwater: No
Pervious Land Use
C, Lawn, Mod
Groundwater
Pervious Total 0.33
Impervious Land Use acre
Impervious Total 0
Basin Total 0.33
Element Flows To:
Surface Interflow
MITIGATED LAND USE
Name SITE AND EXISTING STRUCTURES
Bypass: No
Groundwater: No
Pervious Land Use
C, Lawn, Mod
Pervious Total
Impervious Land Use
ROADS MOD
ROOF TOPS FLAT
PARKING FLAT
Impervious Total
Basin Total
Element Flows To:
Surface
R-TANK
Name UPSTREAM
Bypass: No
Groundwater: No
Pervious Land Use
C, Lawn, Mod
acre
.311
0.311
Groundwater
acre
0.235
0 . 012 Z )pf6P0ZP&OD Lea :' ),
L7 H6 0,5.r 0 , 0 S AC�
0.285 ix CA 4P&� ' 96or ( 6 E a Zs A
0 .5 9 6 Lxe 0c _ PAW /O
Interflow
R-TANK
Pervious Total 0.33
Groundwater
Impervious Land Use
Impervious Total
Basin Total
Element Flows
Surface
R-TANK
To:
acre
C�7
0.33
Interflow
R-TANK
Groundwater
Name R-TANK
Width 2695 f t. votvmC RMPIUD Mo n
Length 53 ft.
Depth: 5.92 ft.
Discharge Structure �A ' 0
Riser Height: 4.92 ft.
Riser Diameter: 18 in.
Notch Type: Rectangular
Notch Width: 0.010 ft.
Notch Height: 1.953 ft.
Orifice 1 Diameter: 0.902 in
Element Flows To:
Outlet 1 Outlet 2
114
Elevation: 0 ft.
Vault
Hydraulic
Table
Stage
(feet)
Area(ac.)
Volume(ac-ft.)
Discharge(efs)
In£ilt(cfs)
0.0000
0.0658
0.1316
0.1973
0.2631
0.3289
0.3947
0.4604
0.5262
0.5920
0.6578
0.7236
0.7893
0.8551
0.9209
0.9867
1.0524
1.1182
1.1840
1.2498
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.032
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.017
0.019
0.021
0.023
0.025
0.027
0.029
0.031
0.033
0.036
0.038
0.040
0.000
0.005
0.008
0.009
0.011
0.012
0.013
0.015
0.016
0.017
0.017
0.018
0.019
0.020
0.021
0.021
0.022
0.023
0.024
0.024
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.3156 0.032 0.042 0.025 0.000
1.3813 0.032 09044 0.025 06000
194471 0.032 0.046 0.026 09000
195129 0.032 0.048 0.027 00000
195787 0.032 09050 06027 04000
1.6444 09032 09053 0.028 00000
197102 0.032 09055 0.028 0.000
1.7760 09032 09057 0.029 04000
1.8418 0.032 0.059 0.030 00000
1.9076 0.032 0.061 0.030 00000
1.9733 0.032 0.063 06031 00000
2.0391 09032 09065 09031 06000
2.1049 0.032 0.067 09032 06000
2.1707 0.032 09070 0.032 00000
2.2364 09032 09072 0.033 00000
293022 0.032 0.074 0.033 00000
293680 0.032 0.076 0.034 00000
294338 0.032 0.078 09034 0.000
204996 0.032 06080 09034 00000
2.5653 0.032 0.082 09035 00000
206311 0.032 0.084 0.035 0.000
2.6969 09032 09087 0.036 00000
297627 0.032 0.089 0.036 04000
298284 0.032 06091 0.037 00000
298942 0.032 0.093 0.037 00000
2.9600 0.032 09095 0.038 00000
3.0258 0.032 0.097 0.038 06000
3.0916 0.032 00099 0.040 06000
3.1573 0.032 00101 0.041 06000
362231 0.032 0.103 09043 00000
392889 0.032 0.106 0.045 00000
3.3547 09032 09108 0.047 00000
3.4204 0.032 00110 0.050 00000
3.4862 0.032 0.112 0.052 00000
3.5520 0.032 09114 0.054 04000
3.6178 0.032 0.116 0.057 00000
3.6836 0.032 0.118 00059 00000
3.7493 0.032 0.120 0.062 00000
3.8151 0.032 0.123 09064 08000
3.8809 0.032 09125 09067 00000
3.9467 0.032 09127 0.069 00000
4.0124 0.032 0.129 09072 00000
4.0782 0.032 0.131 0.075 00000
4.1440 0.032 0.133 0.078 0.000
4.2098 0.032 0.135 0.082 00000
492756 0.032 0.137 0,085 00000
4.3413 0.032 0.140 0.088 0.000
4.4071 0.032 09142 0.107 00000
4.4729 0.032 0.144 0.111 00000
4.5387 0.032 0.146 09116 00000
4.6044 0.032 0.148 09121 04000
496702 0.032 0.150 0.125 0.000
4.7360 09032 09152 0.130 0.000
4.8018 0.032 0.154 0.135 00000
4.8676 0.032 0.156 0.140 0.000
4.9333 09032 0.159 0.169 00000
499991 0.032 0.161 0.499 00000
5.0649 0.032 0.163 1.018 0.000
5.1307 0.032 0.165 1.660 0.000
5.1964 0.032 0.167 2.380 0.000
5.2622 0.032 0.169 3.130 0.000
5.3280 0.032 0.171 3.866 0.000
5.3938 0.032 0.173 4.542 0.000
5.4596 0.032 0.176 5.121 0.000
5.5253 0.032 0.178 5.581 0.000
5.5911 0.032 0.180 5.922 0.000
5.6569 0.032 0.182 6.174 0.000
5.7227 0.032 0.184 6.497 0.000
5.7884 0.032 0.186 6.753 0.000
5.8542 0.032 0.188 6.999 0.000
5.9200 0.032 0.190 7.236 0.000
5.9858 0.027 0.165 7.466 0.000
ANALYSIS RESULTS
Stream Protection Duration
?redeveloped Landuse Totals for POC #1
Total Pervious Area:0.926
Total Impervious Area:O
Mitigated Landuse Totals for POC #1
Total Pervious Area:0.641
Total Impervious Area:0.285
Flow Frequency Return Periods for ?redeveloped. POC #1
Return Period Flow(efs)
2 year 0.071562
5 year 0.120312
10 year 0.15785
25 year �0.210869
50 year 09254248
100 year 09300841
Flow Frequency Return Periods for Mitigated. POC #1
Return Period Flow(cfs)
2 year 0. 033703
5 year 0.050812
10 year 0.064989 < Olds Q a �f
25 year 09086611
50 year 09105731
100 year 0.127722
Stream Protection Duration
Annual Peaks for ?redeveloped and Mitigated. POC #1
Year ?redeveloped Mitigated
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
0.134
09129
09084
0.037
0.025
0.058
0.061
0.076
0.088
0.049
0.039
09092
0.062
09022
0.068
0.067
0.079
09042
09132
09076
06074
06066
09083
0a119
09032
0.082
0.095
0.063
0.053
09060
09026
0.183
0.061
0.145
00069
0.041
09047
0.083
09077
09027
0.024
0.029
0.034
09080
0.024
0.024
0.031
0.035
0.036
0.030
0.031
09028
0.065
0.029
0.022
0.030
09029
0.031
0.026
0.033
0.027
06028
0.028
0.033
0.047
0.027
09030
0.033
0.032
0.019
09030
0.022
0.049
0.026
06063
0.033
0.024
09027
0.046
0.052
0.026
0.022
1990
1991
1992
1993
1994
1995
1996
1997
1998
09293
0.183
00055
0.034
0.020
0.051
09152
00091
0.064
0.079
0.069
09029
0.027
0.019
0.034
0.082
0.066
0.027
1999
2000
2001
2002
2003
2004
2005
09214
09071
0.029
0.108
0.122
0.141
09073
09044
0.031
0.020
0.049
0.025
0.116
0.033
2006
2007
2008
2009
0.073 0.032
0.255 0.118
0.191 0.135
0.109 0.041
Stream Protection Duration
Ranked
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
Annual Peaks for
Predeveloped
0.2935
0.2551
0.2138
0.1907
0.1834
0.1830
0.1524
0.1449
0.1406
0.1341
0.1324
0.1286
0.1218
0.1187
0.1093
0.1083
0.0947
0.0917
0.0910
0.0878
0.0838
0.0827
0.0825
0.0824
0.0792
0.0775
0.0762
0.0762
0.0740
0.0734
0.0728
0.0706
0.0690
0.0682
0.0668
0.0662
0.0636
0.0635
0.0616
0.0612
0.0605
0.0596
0.0581
0.0552
0.0532
0.0511
0.0489
48 0.0471
Predeveloped and Mitigated. POC #1
Mitigated
0.1350
0.1177
0.1155
0.0816
0.0799
0.0794
0.0690
0.0657
0.0653
0.0632
0.0525
0.0488
0.0487
0.0468
0.0455
0.0441
0.0413
0.0356
0.0347
0.0341
0.0339
0.0334
0.0332
0.0331
0.0330
0.0328
0.0319
0.0316
0.0312
0.0310
0.0308
0.0308
0.0305
0.0303
0.0299
0.0297
0.0294
0.0292
0.0287
0.0287
0.0283
0.0278
0.0277
0.0275
0.0272
0.0269
0.0268
0.0267
49 0.0421 0.0264
50 0.0414 0.0259
51 0.0385 0.0256
52 0.0373 0.0246
53 0.0337 0.0242
54 0.0322 0.0239
55 0.0288 0.0237
56 0.0274 0.0224
57 0.0255 0.0220
58 0.0247 0.0218
59 0.0242 0.0196
60 0.0223 0.0192
61 0.0204 0.0192
Stream Protection Duration
POc #1
The Facility PASSED
The Facility PASSED.
Flow(cfs) Predev Mit Percentage Pass/Fail
0.0358 4201 4034 96 Pass
0.0380 3465 2774 80 Pass
0.0402 2896 2250 77 Pass
0.0424 2419 1898 78 Pass
0.0446 2081 1647 79 Pass
0.0468 1779 1392 78 Pass
0.0490 1482 1192 80 Pass
0.0512 1277 1054 82 Pass
0.0534 1119 927 82 Pass
0.0556 982 817 83 Pass
0.0578 836 725 86 Pass
0.0601 674 635 94 Pass
0.0623 548 518 94 Pass
0.0645 453 405 89 Pass
0.0667 365 349 95 Pass
0.0689 299 292 97 Pass
0.0711 257 245 95 Pass
0.0733 222 212 95 Pass
0.0755 197 185 93 Pass
0.0777 171 155 90 Pass
0.0799 147 122 82 Pass
0.0821 129 102 79 Pass
0.0843 113 92 81 Pass
0.0865 103 83 80 Pass
0.0887 95 74 77 Pass
0.0909 91 71 78 Pass
0.0932 81 69 85 Pass
0.0954 75 66 88 Pass
0.0976 68 62 91 Pass
0.0998 62 59 95 Pass
0.1020 61 58 95 Pass
0.1042 60 55 91 Pass
0.1064 57 52 91 Pass
0.1086 54 48 88 Pass
0.1108 52 43 82 Pass
0.1130
0.1152
0.1174
51
48
45
36
27
19
70
56
42
Pass
Pass
Pass
0.1196
0.1218
41
37
12
11
29
29
Pass
Pass
0.1241
0.1263
0.1285
0.1307
091329
0.1351
33
33
31
28
26
25
9
8
7
6
4
0
27
24
22
21
15
0
Pass
Pass
Pass
Pass
Pass
Pass
0.1373
0.1395
091417
0.1439
0.1461
0.1483
22
22
19
19
15
14
0
0
0
0
0
0
0
0
0
0
0
0
Pass
Pass
Pass
Pass
Pass
Pass
091505
0.1527
0.1549
0.1572
001594
0.1616
0.1638
091660
0.1682
14
13
13
12
12
12
12
12
12
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
0.1704
0.1726
0.1748
0.1770
0.1792
0.1814
0.1836
001858
091880
091903
091925
0.1947
0.1969
0.1991
0.2013
0.2035
0.2057
0.2079
0.2101
11
11
10
9
8
8
6
6
6
6
5
5
5
5
5
5
5
5
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
092123
0.2145
092167
092189
0.2211
0.2234
0.2256
0.2278
0.2300
5
4
3
3
3
2
2
2
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
0.2322
0.2344
0.2366
2
2
2
0
0
0
0
0
0
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Pass
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0.2388
0.2410
2
2
0
0
0
0
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092432
0.2454
0.2476
2
2
2
0
0
0
0
0
0
Pass
Pass
Pass
0.2498
2
0
0
Pass
0.2520
2
0
0
Pass
0.2542
2
0
0
Pass
Appendix
Predeveloped Schematic
RAVI 7/18/2022 3:19:21 PM
Mitigated Schematic
RAVI 7/18/2022 3:19:24 PM
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Reduce the size with the R-Tank System, an efficient
and versatile underground stormwater storage system.
This system will reduce your underground stormwater
storage system footprint to resolve a utility conflict or
free up space for a future expansion.
It will also provide additional options for vehicular
loading and cover depths, and deliver greater
installation versatility.
Ilia
With five different module configurations, R-Tank
provides system height options from 2" to over 7' deep.
It also delivers support for HS-20 and HS-25 traffic, with
cover depths from 6" to over 16'.
2
1 L
Many factors will influence the design of the R-Tank°
system. While this list is not intended to be all-inclusive,
the following design considerations are worth
highlighting:
1. PRE-TREATMENT
Removing pollutants from runoff before they enter
an underground detention system is the smart way to
design & build a system. Trash Guard Plus® (see page 6)
is a great tool for this. Be sure the system you select will
remove, heavy sediments, gross pollutants (trash) and
biodegradable debris.
2. BACKFILL MATERIALS
Backfill materials should be stone (<1.5" in diameter) or
soil (GW, GP SW or SP per the Unified Soil Classification
System). Material must be free from lumps, debris
and sharp objects that could cut the geotextile. See
the R-Tank° narrative specification section 2.03 for
additional information.
3. RUNOFF REDUCTION
Most designs incorporate an outlet to drain the system
at a controlled rate and/or an overflow to prevent
flooding in extreme events. Any infiltration that can be
achieved on the site should also be taken advantage of.
Consider raising the invert of your outlet or creating a
sump to capture and infiltrate the water quality volume
whenever possible.
TOTAL COVER: 20" AIINU.IUA1 AND 84- I.NXIAIUAI. FIRST 12' 0.SUST BE
FREE DRAINING BACKFILL (SPEC SECTION 2.030): STONE <1.5' OR SOIL
(USCS CLAS$ GW, GP, SW OR SP} ADDITIONAL FILL AIAV BE
STRUCTURAL FILL (SPEC SECTION 2.03C): STONE OR SOfL (USCS
CLASS SM, SP, SW, GM, GP OR GWI WITH MAX CLAY CONTENT<70%,
P (AX 25% PASSING NO.200 SIEVE, AND MAX PLASTICITY INDEX OF 4.A
MIN. 12' COVER MUST BE MAINTAINED BETWEEN BACKFILL
EQUIPMENT AND THE TOP OF THE R-TANK' SYSTEM AT ALL TIMES.
TOTAL HEIGHT OF TOP BACKFILL SHOULD NOT EXCEED 7'. CONTACT
ACF ENVIRONMENTAL IF MORE THAN TOR LESS THAN 20" OF TOP
BACKFILL IS REQUIRED (FROM TOP OF TANK TO TOP OF PAVEMENT).
UTILITY MARKERS AT
CORNERS (TYP.)
INLET PIPE � T�I -II -
E I�IEI I�F�II I ;
m)
R-TAtIKro UNITS VIRAPPED IN S OZ.
NONWOVEN GEOTEXTILE (OR EQUAL)
LOAD RATING: 33 4 PSI (AIDDDLE ONLY)
SUBGRADE I EXCAVATION LINE: COt.IPACT PER
SPEC SECTION 3.02 D. A BEARING CAPACITY
OF 2,000 PSF MUST BE ACHIEVED PRIOR TO
INSTALLING R-TANKro
4. WATER TABLE
While installing R-Tank° below the water table is
manageable, a stable base must be created to account
for the system's ability to drain water out or limit its
ability to enter the system. If a liner is used to prevent
ground water from entering, measures must be taken to
prevent the system from floating.
5. CONSTRUCTION LOADS
Construction loads are often the heaviest loads the
system will experience. Care must be taken during
backfilling and compaction (see specification section
3.05), and post -installation construction traffic should be
routed around the system (Install Guide step 12).
6. LATERAL LOADS
As systems get deeper, the loads acting on the sides of
the tank increase. While vertical loads often control the
design, lateral loads should also be considered.
7. R-TANK MODULES
Selecting the right module for your application is critical.
See page 3 and the specs on the back of this brochure,
for details. Our team is also here to help!
8. LOAD MODELING
A safety factor of >1.75 is required when designing an
R-Tank System using the AASHTO LRFD Bridge Design
Specifications. It is also necessary to run your own
loading model with specific site requirements. Example
models can be found in our Tech Note on loading
capabilities, and minimum cover requirements can be
found in the specs on the back of this brochure.
NOTES:
1. FOR COMPLETE MODULE DATA, SEE APPROPRIATE R-TANKro MODULE SHEET.
2. INSTALLATIONS PER THIS DETAIL h1EET GUIDELINES OF HL-93 LOADING PER THE AASHTO LRFD
BRIDGE DESIGN SPECIFICATK)NS, CUSTOAIARV U.S. UNITS, 7TH EDITION, 2014 WITH 2O15 AND
2016 INTERIM REVISIONS.
3. PRE-TREATMENT STRUCTURES NOT SHOWN.
4. FOR INFILTRATION APPLICATIONS, GEOTEXTILE ENVELOPING R-TANKSHALL BE ACF t.1200(PER
SPEC SECTION 2.02A) AND BASE SHALL BE 4' MIN. UNCOMPACTED FREE DRAINING BACKFILL
(SPEC SECTION 2.03A)TO PROVIDE A LEVEL BASE. SURFACE MUST BE SMOOTH, FREE OF LUMPS
OR DEBRIS, AND EXTEND T BEYOND R-TANKS FOOTPRINT.
GEOGRID (ACF BX-12 OR EQUAL) PLACED 12' ABOVE THE R-TANKro
SYSTEM. OVERLAP ADJACENT PANELS BY 18" MIN. GEOGRID
SHOULD EXTEND T BEYOND THE EXCAVATION FOOTPRINT.
PAVED �36-(0'9�m)AIIN. COVER FROM FINISH
OFT
SURFACE
GRADE TO TOP OF TANK
20'(0.57 m) MIN.
_ _ _. .. ... W(2.13 m)MAX.
T;
24" (0.67
BASE: 3" I.IIN. BEDDING MATERIAL (SPEC SECTION
2.07A) h1AY BE STOtJE (<1.5"I OR SOIL (USCS CLASS 6W,
GP, SW OR SPA. P.IUST BE FREE OF LLIAIPS AHD DEBRIS,
AND EXTEND 2' BEYOND R-TANK�O.
COP.(PACT PER
SPEC SECTION 3 03 A. NATR/E SOILS AIAY BE USED IF
THEY MEET THE REOUIRElAENTS OF SPEC SECTION
2.03A AND ARE ACCEPTED BY OA"BIER'S ENGINEER.
OPTIONAL
OVERFLOW
PIPE
I� oanorlAL
OUTLET
PIPE
SIDE BACKFILL 24' AIIN. OF FREE DRAINING
BACKFILL (SPEC SECTION 2.038): STONE <1.5'
OR SOIL (USCS CLASS G W, GP, SW OR SP).
h1U5T BE FREE FROI.1 LUA1P5, DEBRIS AND
OTHER SHARP OBJECTS. SPREAD EVENLY TO
PREVENT R-TAl1K^� MOVEMENT. COhIPACT
SIDE BACKFILL WITH POWERED MECHANICAL
COMPACTOR IN 72" LIFTS (PER SPEC SECTION
3.05 A2).
0
As much of the nation's Gray Infrastructure continues to decay, new concepts for rebuilding it are emerging through
Green Infrastructure (GI) and Low Impact Development (LID). This type of reconstruction moves beyond traditional
systems that do one thing well, to systems that accomplish multiple objectives simultaneously.
ACF Environmental has several technologies that dovetail with the goals of LID and GI and can playa significant role in
the redevelopment process.
R-TANK°
Pipe and stone are used in traditional systems to move
and store runoff. R-Tank accomplishes the same purpose
with several additional benefits.
Traditional pavements move vehicles efficiently, but
are easily damaged by stormwater. ACF Environmental
specializes in permeable pavements that handle traffic
loads, while providing surface infiltration rates 10x higher
than traditional pervious pavements, helping reduce the
expense of long-term maintenance.
FOCALPOINT
Traditional landscaping adds aesthetic value to
projects, but has more potential. Many developers
turn to bioretention, but are forced to surrender
massive land areas and dedicate significant future
funds to maintenance. FocalPoint reduces the space
requirements and maintenance costs of bioretention by
up to 90% while providing similar pollutant removal.
• Stores and moves runoff
• Moves water slowly, increasing time of concentration
• Open system encourages infiltration
• Fully accessible for maintenance
• Stores 138% more water than stone
° Maximizes storage potential of GI practices
• Easily handles traffic loads
• Ships flat to reduce site disturbance
• Handles all vehicular loads
• Drains ten times faster than competing pervious
pavements
• Reduces long-term maintenance costs
• Encourages infiltration
• Pair with R-Tank° to maximize water storage and
transport
• Adds aesthetic value to properties
• Cleans runoff to improve water quality
Reduces space requirements and maintenance costs
of traditional bioretention systems
• Encourages infiltration to reduce volume of water
discharged
• Pairs with R-Tank® to maximize water storage and
transport
R-Tank maximizes the storage capabilities of
bioretention and permeable pavement systems.
SECTION V
CONVEYANCE SYSTEM ANALYSIS AND
DESIGN
SECTION VI
SPECIAL REPORTS AND STUDIES
.
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SAA VENTURES, LLC
November 2, 2021
Lvels�� VL
Chase G. Waken, L.G.
Project Geologist
Engineering Goologist
oe�sed Ge°�°� 11 /02/2021
Scott S. Riegel
Scott S. Riegel, L.G., L.E.G.
Senior Project Manager
O
Amlawoo
-• • • Washington 98052
• - 425=449=4704 FaxK 42544947
www.earthsolutionsnw.com
responsibility or liability for problems that arise because the geotechnical
engineer was not informed about developments the engineer othenvise
would have considered.
Most of the ndings" Related in Phis Report
Are Professional ®pinions
Before construction begins, geotechnical engineers explore a site's
subsurface using various sampling and testing procedures. Geotechnical
engineers can observe actual subsurface conditions only at those specific
locations where sampling and testing is perfornied. The data derived from
that sampling and testing were reviewed by your geotechnical engineer,
who then applied professional judgement to form opinions about
subsurface conditions throughout the site. Actual sitewide-subsurface
conditions may differ — maybe significantly — from those indicated in
this report. Confront that risk by retaining your geotechnical engineer
to serve on the design team through project completion to obtain
informed guidance quickly, whenever needed.
This Report's Recommendations Are
Confirmation -Dependent
The recoumnendations included in this report — including any options or
alternatives — are confirmation -dependent In other words, they are not
final, because the geotechnical engineer who developed them relied heavily
on judgement and opinion to do so. Your geotechnical engineer can finalize
the recommendations only after observing actual subsunface conditions
exposed during construction. If through observation your geotechnical
engineer confirms that the conditions assumed to exist actually do exist,
the recommendations can be relied upon, assuming no other changes have
occurred. The geotechnical engineer who prepared this report cannot assume
responsibility at, liability for confirmation -dependent reconnnendations if you
fail to retain that engineer to pe>forni construction observation.
This Report Could Be Misinterpreted
Other design professionals' misinterpretation ofgeotechnical-
engineering reports has resulted in costly problems. Confront that risk
by having your geotechnical engineer serve as a continuing member of
the design team, to:
• confer with other design -team members;
• help develop specifications;
• review pertinent elements of other design professionals' plans and
specifications; and
be available whenever geotechnical-engineering guidance is needed.
You should also confront the risk of constructors misinterpreting this
report. Do so by retaining your geotechnical engineer to participate in
prebid and preconstruction conferences and to perform construction -
phase observations.
Give Constructors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can shift
unanticipated -subsurface -conditions liability to constructors by limiting
the information they provide for bid preparation. To help prevent
the costly, contentious problems this practice has caused; include the
complete geotechnical-engineering report, along with any attachments
or appendices, with your contract documents, but be certain to note
conspicuously that you've included the material for inforniation purposes
only. To avoid misunderstanding, you may also want to note that
ormational purposes" means constructors have no right to rely on
the interpretations, opinions, conclusions, or recommendations in the
report. Be certain that constructors know they may learn about specific
project requirements, including options selected from the report, only
from the design drawings and specifications. Remind constructors
that they may perform their own studies if they want to, and be sure to
allow enough time to permit them to do so. Only then might you be in
a position to give constructors the information available to you, while
requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions. Conducting prebid and
preconstruction conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. This happens in part because soil and rock on
project sites are typically heterogeneous and not manufactured materials
with well-defined engineering properties like steel and concrete. That
lack of understanding has nurtured unrealistic expectations that have
resulted in disappointments, delays, cost overruns, claims, and disputes.
To confront that risk, geotechnical engineers commonly include
explanatory provisions in their reports. Sometimes labeled "limitations,"
many of these provisions indicate where geotechnical engineers'
responsibilities begin and end, to help others recognize their own
responsibilities and risks. Read these provisions closely. Ask questions.
Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
envhonmental study — e.g., a "phase -one" or "phase -two" environmental
site assessment — differ significantly from those used to perform a
geotechnical-engineering study. For that reason, a geotechnical-engineering
report does not usually provide environmental findings, conclusions, or
recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Unanticipated subsun face
environmental problems have led to project failures. If you have not
obtained your own environmental information about the project site,
ask your geotechnical consultant for a recommendation on hoxv to find
environmental risk -management guidance.
Obtain Professional Assistance to Deal with
Moisture Infiltration and Mold
While your geotechnical engineer ma}' have addressed grouudwater,
water infiltration, or similar issues in this report, the engineer's
services were not designed, conducted, or intended to prevent
migration of moisture — including water vapor — from the soil
through building slabs and walls and into the building interior, where
it can cause mold growth and material -performance deficiencies.
Accordingly, proper implementation of the geotechnical engineer's
recommendations svill not of itself be sufficient to prevent
moisture infiltration. Confront the risk of moisture infiltration by
including building -envelope or mold specialists on the design team.
Geotechnical engineers are not building -envelope or mold specialists.
Telephone: 301/565-2733
e-hail: info@geoprofessional.org www.geoprofessional.org
Copyright 2019 by Geoprofessiona] Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly
prohibited, except with GBA's specific n°ritten permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of
GBA, and only for purposes of scholarly research or book review. Only members oEGBA may use this document or its wording as a complement to or as an element of a report of any kind.
Any other firm, individual, or other entity that so uses this document wi tout being a GBA member could be connnitting negligent or ntentional (t audulent) misrepresentation.
November 2, 2021
ES-8178
SAA Ventures, LLC
6463 — 167'" Lane Southeast
Bellevue, Washington 98006
Attention: Mr. Ravikumar Mandaleeka
Mr. Kiran Komaravolu
Greetings, Gentlemen:
Earth Solutions NW LLC
Geotechnica) Engineering, Construction
Obseivation/Testing and Environmental Services
Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical engineering report in
support of the proposed development. We understand the project is pursuing construction of a
residential short plat and associated infrastructure improvements. From a geotechnical
standpoint, development as currently proposed is feasible. Based on the conditions encountered
during our subsurface exploration, the site is underlain by glacial till deposits.
In our opinion, the proposed residential structures can be constructed on conventional continuous
and spread foundations bearing on competent native soil, recompacted native soil, or new
structural fill placed directly on competent native soils. Native soils considered capable for
support of the proposed residences are anticipated to be first encountered at depths of about two
to four -and -one-half feet below existing grades. Where loose or otherwise unsuitable soil
conditions are encountered at foundation subgrades, additional compaction efforts or
overexcavation and restoration with structural fill will likely be necessary.
From An geotechnical standpoint, full infiltration is considered infeasible for the project given the
widespread presence of unweathered glacial till across the site. Low -impact development
designs or limited infiltration elements, such as permeable pavement and bio-filtration, is
considered feasible provided that it is targeted to the weathered soil horizon encountered within
the upper few feet of existing grades. A further discussion of infiltration feasibility and design
considerations are provided within this report.
We appreciate the opportunity to be of service to you on this project. If you have any questions
regarding the content of this geotechnical engineering study, please call.
Sincerely,
-�TV
LOGO
Project Geologist
15365 N.E. 90th Street, Suite 100 Rechnond, WA 98052 (425) 449-4704 •FAX (425) 449-4711
Table of Contents
f7_[r7
INTRODUCTION.................................................................................
General..................................................................................... 1
ProiectDescription................................................................. 2
SITE CONDITIONS............................................................................. 2
Surface..SON MEN ............................ sea .... sea ................ MEANER .....stages . sea .s 2
Subsurface......... UWE Wg***Nv * 4 * * a 6 0 a * 0 R 0 a 0 a a 0 a 0 A a A a a a a a a 0 E a a 0 0 a a a a 0 a ff V 0 a a a a W I a A a a a a 0 K V a 2
Topsoil and Fill............................................................. 3
NativeSoil..................................................................... 3
Geologic Setting. Not*&* ON outgo maggam 0 a a a a a X 0 a I a ff 0 a 0 K a 0 0 K 0 0 0 a 6 A a b a 0 a 6 a a v 6 0 a a 3
Groundwater... assessawass gas ova I peso amasses 0 0 0 0 0 0 0 N 0 0 a 0 ff E a A a A a a ff 0 & 0 a 0 a a 0 8 1 dr 0 3
Critical Areas Review............................................................0 4
DISCUSSION AND RECOMMENDATIONS ....................................... 4
General..................................................................................... 4
Site Preparation and Earthwork ............................................. 4
Temporary Erosion Control.............. &bad&& mamma as**@ PRO @of Rise* 4
Excavations and Slopes .............................................. 5
In -situ and Imported Soil ............................................. 5
Structural Fill................................................................ 6
Subgrade Preparation.... mamsmammom mosamm to moo mamma motors *SOON OWNS NO OVA 6
Wet Season Grading.. . OPRMFB mmmm As an No Reassess 056 bases* toasts ROOS Raise a 6
Foundations............................................................................ 7
SeismicDesign....................................................................... 8
Slab -on -Grade Floors............................................................. 8
RetainingWallsI ....................................................................... 9
Drainage................................................................................... 10
Infiltration Evaluation. . a a 9 X I V 9 0 A ft & a I a a k a 0 a R a a 2 0 v 0 a a k 0 a a a 5 a a a 0 0 a 0 0 R a a 0 a 0 0 10
Preliminary Pavement Sections......... NKRENENRNMM Samoa mousslas Mae 0 Basses an 11
Utility Support and Trench Backfill....................................... 12
LIMITATIONS.......... opus a mamma as 040 00 Val a Osseo map an Ramos EWE ROE mamma most 994 gas 0 NSA** @*Wave Not Voss
12
Additional Services................................................................. 12
Earth Solutions NW, LLC
Table %J Contents
Cont'd
Plate 1 Vicinity AAap
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration
Test Pit Logs
Laboratory Test Results
Earth Solutions NW, lLC
1
PROPOSED
R •P., SHORT l
6304 ,i
THY JliJ
This geotechnical engineering study was prepared for the proposed residential short plat to be
constructed at 6304 Southeast 2nd Place, in Renton, Washington. The purpose of this study was
to provide geotechnical recommendations for the proposed development and included the
following geotechnical services:
® Test pits to characterize site soil and groundwater conditions.
® Laboratory testing of representative soil samples collected at the test pit locations.
® Engineering analyses.
® Preparation of this geotechnical engineering study.
The following documents and resources were reviewed as part of our report preparation:
® Geologic Map of the Renton Quadrangle, Washington, prepared by D.R. Mullineaux, 1965.
® Online Web Soil Survey (WSS) resource, maintained by the Natural Resources
Conservation Service under the United States Department of Agriculture (USDA).
® Surface Water Design Manual, prepared by the City of Renton, Washington, dated
December 12, 2016.
® GIS mapping application, maintained by the City of Renton, Washington.
® Title IV of the Renton Municipal Code.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Protect Description
ES-8178
Page 2
We understand the project is pursing construction of a four -lot short plat. The existing residence
will remain and the parcel will be subdivided to create three new home building sites. At the time
of report submission, specific building load plans were not available for review. Based on our
experience with similar developments, the proposed residential structures will likely be two to
three stories each and constructed using relatively lightly loaded wood framing supported on
conventional foundations. Perimeter footing loads will likely be about 2 to 3 kips per lineal foot.
Slab -on -grade loading is anticipated to be approximately 150 pounds per square foot (psf). We
anticipate a combination of grade modifications (cuts or fills) of about five feet will likely be
required to establish design building pad elevations.
The feasibility of infiltration is being investigated as part of the project stormwater management
)lans.
If the above design assumptions either change or are incorrect, ESNW should be contacted to
review the recommendations provided in this report. ESNW should review final designs to
confirm that appropriate geotechnical recommendations have been incorporated into the plans.
SITE CONDITIONS
Surface
The subject site is located along the north side of Southeast 2"d Place, about 130 feet west of the
intersection with 156th Avenue Southeast, in Renton, Washington. The approximate site location
is depicted on Plate 1 (Vicinity Map). The site area consists of King County parcel number
142305-9033 and totals about 0.99 acre. Topography descends to the southwest with about 18
feet of elevation change occur across the site. Surface vegetation consists primarily of hard and
soft landscaping features. The site is currently developed with a single-family residence and is
bordered to the north, east, and west by single-family residences and to the south by Southeast
2"d Place.
Subsurface
An ESNW representative observed, logged, and sampled the excavation of five test pits on
September 27, 2021. The test pit exploration was performed using amini-trackhoe and operator
retained by our firm. The approximate locations of the test pits are depicted on Plate 2 (Test Pit
Location Plan). Representative soil samples collected at the test pit locations were analyzed in
general accordance with Unified Soil Classification System (USCS) and USDA methods and
procedures.
The following sections provide a generalized characterization of the encountered subsurface
conditions. Please refer to the test pit logs provided in Appendix A for a more detailed description
of subsurface conditions.
Earth Solutions NW, LLC
SAA ventures, LLC
November 2, 2021
Topsoil Cl" Fill
ES-8178
Page 3
Topsoil was encountered in the upper approximate 4 to 12 inches of existing grades at the test
pit locations. The topsoil was characterized by a dark brown color, trace organic matter, and root
inclusions.
Fill was encountered at TP-4 and TP-5 during our subsurface exploration. The fill was
characterized as dark brown silty sand in a loose and moist condition, extending to a depth
between about one to two -and -one-half feet below the ground surface (bgs). Trace debris was
also observed within the fill. The relic topsoil horizon was observed underlying the fill and was
approximately six inches thick.
Underlying topsoil and localized fill, native soils were characterized primarily as silty sand with or
without gravel (USCS: SM). The upper approximate four to four -and -one-half feet was
characterized as the weathered horizon due to the observed brown hue and loose to medium
dense in -situ condition. Thereafter, native soils transitioned into an unweathered condition and
were observed in a dense to very dense state, extending to a maximum exploration depth of
about nine feet bgs. Localized areas of increased sands and gravel contents were locally
observed; however, silty sand is considered the predominate native soil type.
Geologic Setting
The referenced geologic map identifies ground moraine deposits (Qgt), otherwise known as
glacial till, as underlying the site and surrounding areas. Ground moraine deposits (commonly
termed hardpan) are characterized as an unsorted mixture of sand, silt, clay, and gravel. The
referenced WSS resource identifies Alderwood gravelly sandy loam (Map Unit Symbol: AgC) as
underlying the site and surrounding areas. These soils are associated with ridge and hill
landforms and formed in glacial drift. Based on our field exploration, encountered native soils
correlate with local geologic mapping designations of glacial till.
Perched groundwaterwasencountered at three test pit locations, generally at an exposure depth
between about four -and -three-quarters to eight feet bgs. The seepage was characterized as
being minor to heavy with respect to flow volume. We do not characterize the seepage to reflect
the local, shallow groundwater table.
Groundwater seepage rates and elevations fluctuate depending on many factors, including
precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater
elevations and flow rates are higher during the winter, spring, and early summer months.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Critical Areas Review
ES-8178
Page 4
We reviewed the City of Renton (COR) GIS map database to assist our field observations in
identifying the presence of jurisdictionally recognized geological hazard areas both on site and
directly adjacent to the site. We understand that the COR recognizes steep slope, landslide,
erosion, seismic, and coal mine hazards as geological hazard areas. Based on our review of the
'OR GIS database, Renton Municipal Code (RMC), Title IV, Chapter 3, and our field
observations, it is our opinion that none of the above geologic hazards are present on site or
within the immediate vicinity of the site. Therefore, standard development practices and BMPs
may be applied to this project.
Based on the results of our investigation,
feasible from a geotechnical standpoint.
proposal are in reference to structural fill
stormwater management.
Site Preparation and Earthwork
construction of the proposed residential short plat is
The primary geotechnical considerations for the
placement and compaction, foundation design, and
Initial site preparation activities will consist of installing temporary erosion control measures,
establishing grading limits, and site clearing. Subsequent earthwork activities will involve mass
excavation, foundation subgrade preparation activities, and related infrastructure improvements.
temporary Erosion Control
The following temporary erosion and sediment control (TESC) Best Management Practices
(BMPs) should be considered:
® Silt fencing should be placed around the site perimeter, where appropriate.
® Temporary construction entrances and drive lanes should be constructed with at least six
inches of quarry spalls to minimize off -site soil tracking and provide a stable access
entrance surface. A woven geotextile fabric may be placed underneath the quarry spalls
to provide greater stability, if needed.
® When not in use, soil stockpiles should be covered or otherwise protected. Soil stockpiles
should never be placed near the top of a slope.
® Temporary measures for controlling surface water runoff, such as interceptor trenches,
sumps, or interceptor swales, should be installed prior to beginning earthwork activities.
® Dry soils disturbed during construction should be wetted to minimize dust.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
ES-8178
Page 5
Additional TESC BMPs, as specified by the project design team and indicated on the plans,
should be incorporated into construction activities. TESC measures must be actively monitored
and modified during construction as site conditions require, as approved by the site erosion
control lead to ensure proper performance is maintained.
Excavations and Slopes
Based on the soil conditions observed at the test locations, the following allowable temporary
slope inclinations, as a function of horizontal to vertical (H:V) inclination, may be used. The
applicable Federal Occupation Safety and Health Administration (OSHA) and Washington
Industrial Safety and Health Act (WISHA) soil classifications are also provided:
® Loose to medium dense soil 1.5H:1 V (Type C)
® Areas exposing groundwater 1.5H:1V (Type C)
® Dense to very dense native soil 0.75H:1 V (Type A)
Steeper temporary slope inclinations within undisturbed, very dense native soil may be feasible
based on the soil and groundwater conditions exposed within the excavations. If pursued, ESNW
can evaluate the feasibility of utilizing steeper temporary slopes on a case -by -case basis at the
time of construction. In any case, an ESNW representative should observe temporary slopes to
confirm inclinations are suitable for the exposed soil conditions and to provide additional
excavation and slope stability recommendations, as necessary. If the recommended temporary
slope inclinations cannot be achieved, temporary shoring may be necessary to support
excavations. Permanent slopes should be graded to 2H:1 V (or flatter) and planted with
vegetation to enhance stability and minimize erosion potential. Permanent slopes should be
observed by ESNW prior to vegetating and landscaping.
In -situ and Imported Soil
Based on the conditions observed during our subsurface exploration, site soils will exhibit a high
sensitivity to moisture and are not suitable for use as structural fill unless the moisture content is
at or slightly above optimum (determined using modified Proctor ASTM D-1557) prior to
placement and compaction. Successful use of on -site soil as structural fill will largely be dictated
by the moisture content at the time of placement and compaction. Depending on the time of year
construction occurs, remedial measures (such as soil aeration) may be necessary as part of site
grading and earthwork activities. If the on -site soil cannot be successfully compacted, the use of
an imported soil may be necessary.
In our opinion, a contingency should be provided in the project budget for export of soil that cannot
be successfully compacted as .structural fill, particularly if grading activities take place during
periods of extended rainfall activity. In general, soils with fines contents greater than 5 percent
typically degrade rapidly when exposed to periods of rainfall.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
ES-8178
Page 6
Imported structural fill soil should consist of awell-graded, granular soil that can achieve a
suitable working moisture content. During wet weather conditions, imported soil intended for use
as structural fill should consist of a well -graded, granular soil with a fines content of 5 percent or
less (where the fines content is defined as the percent passing the Number 200 sieve, based on
the minus three -quarter -inch fraction).
Structural Fill
Structural fill is defined as compacted soil placed in slab -on -grade, roadway, permanent slope,
retaining wall, and utility trench backfill areas. The following recommendations are provided for
soils intended for use as structural fill:
® Moisture content
® Relative compaction (minimum)
® Loose lift thickness (maximum)
At or slightly above optimum
95 percent (Modified Proctor)
12 inches
The on -site soil may not be suitable for use as structural fill unless a suitable moisture content is
achieved at the time of placement and compaction. If the on -site soil cannot achieve the above
specifications, use of an imported structural fill material will likely be necessary. With respect to
underground utility installations and backfill, local jurisdictions will likely dictate soil type(s) and
compaction requirements.
subgrade Preparation
Foundation and slab subgrade surfaces should consist of competent, undisturbed native soil or
structural fill placed and compacted directly on a competent native soil subgrade. ESNW should
observe subgrade areas prior to placing formwork. Supplementary recommendations for
subgrade improvement may be provided at the time of construction; such recommendations
would likely include further mechanical compaction effort or overexcavation and replacement with
suitable structural fill.
Overexcavation of existing fill in the area of TP-4 and TP-5 should be anticipated prior to mass
grading activities. However, the extent of overexcavation should be evaluated by ESNW at the
time of construction.
Wet Season Grading
Earthwork activities that occur during wet weather conditions may require additional measures to
protect structural subgrades and soils intended for use as structural fill. Site -specific
recommendations can be provided at the time of construction and may include leaving cut areas
several inches above design elevations, covering working surfaces with crushed rock, protecting
structural fill soils from adverse moisture conditions, and additional TESC recommendations.
ESNW can also assist in obtaining a wet season grading permit or extension, where appropriate,
if required by the presiding jurisdiction.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Foundations
ES-8178
Page 7
Based on the conditions encountered during our fieldwork, in our opinion, the proposed
residences can be constructed on conventional continuous and spread foundations bearing on
competent native soil, recompacted native soil, or new structural fill placed directly on competent
native soils. Native soils considered capable for support of the proposed residences are
anticipated to be first encountered at depths of about two to four -and -one-half feet bgs. Where
loose or otherwise unsuitable soil conditions are encountered at foundation subgrades, additional
compaction efforts or overexcavation and restoration with structural fill will likely be necessary.
Provided the foundations will be supported as recommended, the following parameters may be
used for foundation design:
® Allowable soil bearing capacity
® Passive earth pressure*
® Coefficient of friction
2,500 psf
300 pcf (equivalent fluid)
0.40
Assumes sides of the foundation will be backfilled with compacted structural fill.
ESNW must be contacted to review foundation plans and design subgrade elevations to confirm
the presence of suitable soil conditions for support of the proposed foundation loads. Preliminary
review of the foundation plans will also provide an opportunity for ESNW to identify areas that
may require overexcavation and restoration prior to construction.
A one-third increase in the allowable soil bearing capacity may be assumed for short-term wind
and seismic loading conons. The above passive pressure and friction values include afactor-
of-safety of 1.5. With structural loading as expected, total settlement in the range of one inch and
differential settlement of about one-half inch is anticipated. Most settlement should occur during
construction when dead loads are applied.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Seismic Design
ES-8178
Page 8
The 2018 International Building Code (2018 IBC) recognizes the most recent eon %J the
Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic
design, specifically with respect to earthquake loads. Based on the soil conditions encountered
at the boring locations, the parameters and values provided below are recommended for seismic
design per the 2018 IBC.
Parameter
Value
Site Class
C*
Mapped short period spectral response acceleration, SS
(g)
1.371
Mapped 1-second period spectral response acceleration,
Si (g)
0.469
Short period site coefficient, Fa
1.2
Long period site coefficient, Fv
1.5
Adjusted short period spectral response acceleration, SMs (g)
1.645
Adjusted 1-second period spectral response acceleration, SMi (g)
0.703
Design short period spectral response acceleration, SoS
(g)
1.097
Design 1-second period spectral response acceleration,
SDI (g)
0.469
Assumes very dense soil conditions, encountered to a maximum depth of nine feet bgs during the September
2021 field exploration, remain very dense to at least 100 feet bgs. Based on our experience with the project
geologic setting (glacial till) across the Puget Sound region, soil conditions are likely consistent with this
assumption.
Further discussion between the project structural engineer, the project owner (or their
representative), and ESNW may be prudent to determine the possible impacts to the structural
design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide
additional consulting services to aid with design efforts, including supplementary geotechnical
and geophysical investigation, upon request.
Liquefaction is a phenomenon where saturated or loose soil suddenly loses internal strength and
behaves as a fluid. This behavior is in response to increased pore water pressures resulting from
an earthquake or another intense ground shaking. In our opinion, site susceptibility to liquefaction
may be considered negligible. The absence of a shallow groundwater table and the relatively
dense characteristics of the native soil were the primary bases for this opinion.
Slab -on -grade floors for the proposed structure should be supported on competent, well -
compacted, firm, and unyielding subgrades. Unstable or yielding subgrade areas should be
recompacted or overexcavated and replaced with suitable structural fill prior to slab construction.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
ES-8178
Page 9
A capillary break consisting of at least four inches of free -draining crushed rock or gravel should
be placed below each slab. The free -draining material should have a fines content of 5 percent
or less (where the fines content is defined as the percent passing the Number 200 sieve, based
on the minus three -quarter -inch fraction). In areas where slab moisture is undesirable, installation
of a vapor barrier below the slab should be considered. The vapor barrier should be a material
specifically designed for use as a vapor barrier and should be installed in accordance with the
specifications of the manufacturer.
Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The
following parameters may be used for design:
® Active earth pressure (unrestrained condition)
® At -rest earth pressure (restrained condition)
® Traffic surcharge (passenger vehicles)
® Passive earth pressure
® Allowable soil bearing capacity
® Coefficient of friction
® Seismic surcharge
Where applicable.
** Where H equals the retained height (in feet).
35 pcf (equivalent fluid)
55 pcf
70 psf (rectangular distribution)
300 pcf (equivalent fluid)
2,500 psf
0.40
Additional surcharge loading from foundations, sloped backfill, or other loading should be
included in the retaining wall design, as appropriate. Drainage should be provided behind
retaining walls such that hydrostatic pressures do not develop. If drainage is not provided,
hydrostatic pressures should be included in the wall design, as appropriate. ESNW should review
retaining wall designs to verify that appropriate earth pressure values have been incorporated
into the design and to provide additional recommendations, as necessary.
Retaining walls should be backfilled with free -draining material that extends along the height of
the wall and a distance of at least 12 inches behind the wall. The upper one foot of the wall
backfill may consist of a less permeable (surface seal) soil, if desired. In lieu of free -draining
backfill, use of an approved sheet drain material may also be considered, based on the observed
subsurface and groundwater conditions. ESNW should review conditions at the time of
construction and provide recommendations for sheet drain material, as appropriate. A perforated
drainpipe should be placed along the base of the wall and connected to an appropriate discharge
location. A typical retaining wall drainage detail is illustrated on Plate 3.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Drainage
ES-8178
Page 10
Surface grades must be designed to direct water away from the bungs to the extent practical.
The grade adjacent to the buildings should be sloped away at a gradient of at least 2 percent for
a horizontal distance of at least 10 feet (or as building and property setbacks allow). In no
instance should water be allowed to collect, pond, or flow uncontrolled above and over sloping
areas.
Groundwater seepage zones may be encountered during construction, depending on the time of
year grading operations take place. Temporary measures to control surface water runoff and
groundwater seepage during construction would likely involve interceptor trenches and sumps.
ESNW should be consulted during preliminary grading and excavation activities to identify areas
of seepage and to provide recommendations to reduce the potential for seepage -related
instability. In our opinion, foundation drains should be installed along building perimeter footings.
A typical foundation drain detail is provided on Plate 4.
Infiltration Evaluation
To assist in determining infiltration feasibility for the project, ESNW conducted two, small-scale
Pilot Infiltration Tests (PITs) during the September 2021 subsurface exploration. The following
table depicts each infiltration test location, test date, test depth, measured rate, appropriate safety
factors, and recommended design rate.
location
Soil
Type
lest
Depth
ft. b s
tliieasured
Rate
in/hr.
Reduction Factors
Recommended
Design Rate
in/hr.
Ft
Fg
Fp
TP-2
GM
2'
5.5
0.5
1 *
0.7
1.9
TP-3
SM
6'
0.24
0.5
1*
0.7
N/A
Correction factor of facility geometry is assumed at 1. This value may need to be updated upon final facility design.
From a geotechnical standpoint, low -impact -development (LID) designs, such as permeable
pavement, that are targeted to the upper weathered soil horizon is feasible for the proposed
project and native soil conditions. Based on our representative in -situ testing, a long-term design
rate of 1.9 in/hr, is considered appropriate for infiltration facilities that target the weathered soil
horizon, which was generally encountered in the upper approximate three -and -one-half to four
feet of existing grades. Given the consistent nature of the weathered horizon, the above rate
should be considered suitable for site infiltration facilities targeted to this section of the deposit.
Infiltration of any type into the unweathered till deposit in considered infeasible from a
geotechnical standpoint given the very low measured field rate, appreciable fines contents, and
dense to very dense in -situ condition.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
ES-8178
Page 11
Infiltration into the weathered zone should be situated as high within the native soil as possible,
to provide maximum capacity for infiltration. Areas targeted for infiltration will require protection
from traffic, compaction, or other activities that may impede or otherwise degrade the infiltration
capacity. Site runoff and other processes that could lead to sediment accumulation must not be
allowed within areas targeted for infiltration, as this could also degrade the infiltration capacity of
the native soils. Any area that will have a shallow infiltration facility must be identified and
protected prior to, and throughout, mass earthwork operations. Failure to do so may reduce the
infiltration characteristics of the near surface soils. It may be prudent to consider implementing
an overflow provision into the LID designs if practical.
ESNW should review the final grading and storm plans to confirm the recommendations in this
evaluation are incorporated. ESNW should also observe the subgrade for infiltration devices
prior to construction to confirm soil conditions are as anticipated.
Preliminary Pavement Sections
The performance of site pavements is largely related to the condition of the underlying subgrade.
To ensure adequate pavement performance, the subgrade should be in a firm and unyielding
condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement
areas should be compacted to the specifications previously detailed in this report. Soft, wet, or
otherwise unsuitable subgrade areas may still exist after base grading activities. Areas
containing unsuitable or yielding subgrade conditions will require remedial measures, such as
overexcavation and replacement with crushed rock or structural fill, prior to pavement. If roadway
areas will be designed with an inverted crown, additional drainage measures may be
recommended at the time of construction to help maintain subgrade stability and pavement
performance.
For lightly loaded pavement areas subjected primarily to passenger vehicles, the following
preliminary pavement sections may be considered:
® A minimum of two inches of hot -mix asphalt (HMA) placed over four inches of crushed
rock base (CRB).
® A minimum of two inches of HMA placed over three inches of asphalt -treated base (ATB).
The HMA, ATB, and CRB materials should conform to the specifications of the governing
jurisdiction. All soil base material should be compacted to at least 95 percent of the maximum
dry density. Final pavement design recommendations can be provided once final traffic loading
has been determined. City of Renton standards may supersede the recommendations provided
in this report.
Earth Solutions NW, LLC
SAA Ventures, LLC
November 2, 2021
Utility Support and Trench Backfill
ES-8178
Page 12
In our opinion, native soils will generally be competent for support of utilities. In general, native
soils may be suitable for use as structural backfill throughout utility trench excavations, provided
the soils are at (or slightly above) the optimum moisture content at the time of placement and
compaction. Structural trench backfill should not be placed dry of the optimum moisture content.
Each section of the site utility lines must be adequately supported in appropriate bedding material.
Utility trench backfill should be placed and compacted to the specifications of structural fill (as
previously detailed in this report) or to the applicable specifications of the presiding jurisdiction.
This study has been prepared for the exclusive use of SAA Ventures, LLC and its representatives.
No warranty, express or implied, is made. The recommendations and conclusions provided in
this geotechnical engineering study are professional opinions consistent with the level of care
and skill that is typical of other members in the profession currently practicing under similar
conditions in this area. Variations in the soil and groundwater conditions observed at the test pit
locations may exist and may not become evident until construction. ESNW should reevaluate
the conclusions provided in this geotechnical engineering study if variations are encountered.
Additional Services
ESNW should have an opportunity to review the final design with respect to the geotechnical
recommendations provided in this report. EON" should also be retained to provide testing and
consultation services during construction.
Earth Solutions NW, LLC
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TP-1I Approximate Location of
— ®— ESNW Test Pit, Proj. No.
ES-8178, Sept. 2021
Subject Site
Existing Building
NOTE: The graphics shown on this plate are not intended for design
purposes or precise scale measurements, but only to illustrate the
approximate test locations relative to the approximate locations of
existing and ( or proposed site features. The information illustrated
is largely based on data provided by the client at the time of our
study. ESNW cannot be responsible for subsequent design changes
or interpretation of the data by others.
NOTE: This plate may contain areas of color. ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
0 40 80 160
r
NOTES:
18" Min.
00 0 0 p 0 0 p 0 v0
00 CO 0 d% 0 00
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® Free -draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No. 4 sieve should be
25 to 75 percent.
® Sheet Drain may be feasible in lieu
of Free -draining Backfill, per ESNW
recommendations.
® Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
LEGEND:
0 oo 0 Free -draining Structural Backfill
o
1-inch Drain Rock
StCUCl'Ui�al
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY -NOT TO SCALE
NOTA CONSTRUCTION DRAWING
NOTES:
® Do NOT tie roof downspouts
to Footing Drain.
® Surface Seal to consist of
12" of less permeable, suitable
soil. Slope away from building.
LEGEND:
Surface Seal: native soil or
other low -permeability material.
14ch Drain Rock
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY - NOT TO SCALE
NOTA CONSTRUCTION DRAWING
Subsurface Exploration
Test Pit Logs
An ESNW representative observed, logged, and sampled five test pits on September 27, 2021.
The explorations were completed in accessible site areas using a trackhoe and operator retained
by our firm. The test pits were excavated to a maximum exploration depth of about nine feet bgs.
The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). The
test pit logs are provided in this Appendix.
The final logs represent the interpretations of the field logs and the results of laboratory analyses.
The stratification lines on the logs represent the approximate boundaries between soil types. In
actuality, the transitions may be more gradual.
Earth Solutions NW, LLC
MAJOR DIVISIONS SYM OLS TYPICAL
GRAPH LETTER DESCRIPTIONS
CLEAN ' ® ease WELL -GRADED GRAVELS, GRAVEL -
GRAVEL GRAVELS ®® ®® GW SAND MIXTURES, LITTLE OR NO
AND 04D go00 FINES
GRAVELLY Fib
o a Qa POORLY -GRADED GRAVELS,
SOILS (LITTLE OR NO FINES) o D GP GRAVEL - SAND MIXTURES, LITTLE
O C) °O OR NO FINES
COARSE °
GRAINED MORE THAN 50% GRAVELS WITH p GM SILTY GRAVELS, GRAVEL - SAND -
SOILS OF COARSE FINES Vc SILT MIXTURES
FRACTION
RETAINED ON NO.
4 SIEVE (APPRECIABLE G�+ CLAYEY GRAVELS, GRAVEL - SAND -
AMOUNT OF FINES) CLAY MIXTURES
CLEAN SANDS WELL -GRADED SANDS, GRAVELLY
MORE THAN 50% SAND SW SANDS, LITTLE OR NO FINES
OF MATERIAL IS AND
LARGER THAN SANDY
NO, 200 SIEVE SOILS POORLY -GRADED SANDS,
SIZE (LITTLE OR NO FINES) SP GRAVELLY SAND, LITTLE OR NO
FINES
SANDS WITH SILTY SANDS, SAND -SILT
MORE THAN 50% FINES SM MIXTURES
OF COARSE
FRACTION
PASSING ON NO,
4 SIEVE (APPRECIABLE SC CLAYEY SANDS, SAND - CLAY
AMOUNT OF FINES) MIXTURES
INORGANIC SILTS AND VERY FINE
ML SANDS, ROCK FLOUR, SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
SILTS INORGANIC CLAYS OF LOW TO
FINE AND LIQUID LIMIT GL MEDIUM PLASTICITY, GRAVELLY
GRAINED LESS THAN 50 CLAYS, SANDY CLAYS, SILTY CLAYS,
CLAYS LEAN CLAYS
SOILS — — —
— L ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW PLASTICITY
MORE THAN 50% INORGANIC SILTS, MICACEOUS OR
OF MATERIAL IS MH DIATOMACEOUS FINE SAND OR
SMALLER THAN SILTY SOILS
NO, 200 SIEVE
slzE SILTS
LIQUID LIMIT INORGANIC CLAYS OF HIGH
AND
CLAYS GREATER THAN 50 CH PLASTICITY
ORGANIC CLAYS OF MEDIUM TO
OH HIGH PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
HIGHLY ORGANIC SOILS PT HIGH ORGANIC CONTENTS
DUAL SYMBOLS are used to indicate borderline soil classifications.
The discussion in the text of this report is necessary for a proper understanding of the nature
of the material presented in the attached logs.
y Earth Solutions NW, LLC TEST PIT NUMBER TP_1
tar 15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
DATE STARTED 9/27/21 COMPLETED 9/27/21 GROUND ELEVATION ~465
EXCAVATION CONTRACTOR NW Excavating LATITUDE 47,48146 LONGITUDE-122,13322
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY CGH CHECKED BY SSR SZ AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 12": grass
W
= HW U_
w J Co TESTS ¢ J MATERIAL DESCRIPTION
Qz
0
'' Dark brown TOPSOIL, roots to 3'
TPSL;;,a;.,
Brown silty SAND with gravel, loose to moist to wet
MC = 35.5%
Fines = 25.5% [USDA Classification: gravelly fine sandy LOAM]
SM :•
40 -becomes gray, dense
.
MC = 10.6% Gray poorly graded SAND with silt and gravel, very dense, wet
5 SP- -moderate perched groundwater seepage
SM -trace cobbles
6.0
Gray silty SAND, very dense, moist to wet
MC = 12.6% -moderate iron oxide staining
SM :•
MC = 9.5% 9.0
Test pit terminated at 9.0 feet below existing grade. Groundwater seepage encountered at 4.75
feet during excavation. No caving observed.
N
N
F
W
F
J
a
w
F
m
_U
a
a
c6
W
J
J
W
a
m
a
W
w
W
w
V Earth Solutions NW, LLC TEST PIT NUMBER TP=2
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
. ► ► Redmond, Washington 98052
Telephone: 425449-4704
Fax: 425-4494711
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
DATE STARTED 9/27/21 COMPLETED 9/27/21 GROUND ELEVATION �460
EXCAVATION CONTRACTOR NW Excavating LATITUDE 47,48133 LONGITUDE-122,13339
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY CGH CHECKED BY SSR �Z AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 6": grass
W
_ }� U_
t- W Uj 2
w $ J TESTS Q O MATERIAL DESCRIPTION
p D Qf
Q Z C7
0
TPSL ' 0,5 Dark brown TOPSOIL, roots to 4'
Brown silty GRAVEL with sand, loose, damp
becomes gray
MC = 4.1 %
Fines = 12.2% GM [USDA Classification: extremely gravelly sandy LOAM]
)9 MC = 7.2% 4,0
Gray silty SAND with gravel, very dense, moist
5 -heavy iron oxide staining at 4'
SM
MC = 11.4% 8.0
Test pit terminated at 8.0 feet below existing grade. Groundwater seepage encountered at 4.0
feet during excavation. No caving observed.
N
N
H
W
F-
¢
J
a
w
F
m
_U
S
a
0
d
c6
m
J
a
m
J
¢
W
Z
W
Earth Solutions NW, LLC TEST PIT NUMBER iP=3
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
i Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-4494711
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
DATE STARTED 9/27121 COMPLETED 9/27121 GROUND ELEVATION �458
EXCAVATION CONTRACTOR NW Excavating LATITUDE 47,48123 LONGITUDE-122,13316
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY CGH CHECKED BY SSR �Z AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 12": grass
W
H W _
w UJ ED TESTS ¢ O MATERIAL DESCRIPTION
Q z 75 CAD
0
Dark brown TOPSOIL, roots
1.0
Brown silty SAND, loose, damp to moist
MC = 9.3%
5 -becomes gray, dense
SM
MC = 14.9% -6" thick sand/gravel lens, heavy iron oxide staining
Fines = 23.6% [USDA Classification: gravelly sandy LOAM]
-weakly cemented
MC = 11.8%
-minor to moderate perched groundwater seepage
-becomes silty sand with gravel
MC = 9.9% 9.0 [USDA Classification: very gravelly loamy SAND]
Fines = 16.5% Test pit terminated at 9.0 feet below existing grade. Groundwater seepage encountered at 8.0
feet during excavation. No caving observed.
N
H
W
F-
J
a
Uj
w
U)
U_
S
a
a
c6
m
J
J
w
3
a
m
J
K
W
Z
W
14 Earth Solutions NW, LLC TEST PIT NUMBER T =4
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
DATE STARTED 9/27121 COMPLETED 9/27/21 GROUND ELEVATION —442
EXCAVATION CONTRACTOR NW Excavating LATITUDE 47.48157 LONGITUDE-122.13409
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY CGH CHECKED BY SSR SZ AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 4": light brush
w
_ �W U
CO S
w J TESTS ¢ O MATERIAL DESCRIPTION
° QzIL 0
0
Dark brown silty SAND, loose, moist (Fill)
-roots to 3'
SM -garden hose/plastic debris
2,5 -6" thick relic topsoil horizon at south edge of test pit
Brown silty SAND with gravel, loose to medium dense, moist
MC = 23.3%
-becomes gray, dense to very dense
5 -moderate iron oxide staining
SM
MC = 9.4%
-minor to moderate perched groundwater seepage
MC = 15.3% 8.0 [USDA Classification: gravelly sandy LOAM]
Fines = 27.0% Test pit terminated at 8.0 feet below existing grade. Groundwater seepage encountered at 6.0
feet during excavation. No caving observed.
y Earth Solutions NW, LLC -EST IT NUMBER TP_5
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052 PAGE 1 OF 1
Telephone: 425-449-4704
Fax: 425-4494711
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
DATE STARTED 9/27/21 COMPLETED 9/27121 GROUND ELEVATION �465
EXCAVATION CONTRACTOR NW Excavating LATITUDE 47,48145 LONGITUDE-122.13361
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY CGH CHECKED BY SSR AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 12": grass
W
_ of U U
{— W =
w W C2 TESTS Q O MATERIAL DESCRIPTION
p n- D ry
Q Z (�
Dark brown silty SAND with gravel, loose, moist (Fill)
SM �.o -roots to 4', areas of increased organics within the fill
Brown silty SAND, loose to medium dense, moist
MC = 10.9%
Fines = 25.4% [USDA Classification: gravelly sandy LOAM]
-becomes gray, very dense
-very weakly cemented
5 MC = 5.9% SM
MC = 12.2% � 9.0
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Appendix B
Laboratory Test Results
Earth Solutions NW, LLC
t Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
t`v Telephone: 425-449-4704
Fax: 4254494711
IRMIrAM W"' Im*111061Z
PROJECT NUMBER ES-8178 PROJECT NAME 2nd Place Short Plat
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS HYDROMETER
100
95
90
85
80
75
70
65
H
60
w
55
m
w
50
z
v_
45
z
w
40
w
a
35
U)
ti
COoBLES
GRAVEL
SAND
I SILT OR CLA�
coarse
� fine
coarse
medium
fine
a Specimen Identification Classification Cc Cu
Q TP-01 2.00ft. USDA: Brown Gravelly Fine Sandy Loam. USCS: SM with Gravel.
J
® TP=02 1001"t. USDA: Gray Extremely Gravelly Sandy Loam. USCS: GM with Sand. 0.31 328.!
A TP-03 6x00ft. USDA: Gray Gravelly Sandy Loam. USCS: SM.
co
3 TP-03 9.00ft. USDA: Gray Very Gravelly Loamy Sand. USCS: SM with Gravel.
Z
o TP-04 8.0Oft. USDA: Gray Gravelly Sandy Loam, USCS: SM,
Specimen Identification D100 D60 D30 D10 LL PL PI %Silt %Clay
N ® TP=01 2.0ft. 37.5 0.394 0.09 25.5
W
o M TPm02 2.0ft. 37.5 19.12 0.59 12.2
w A TPm03 6.0ft. 19 0.487 0.109 23.6
N
z TP=03 9.Oft. 37.5 2.678 0.215 16.5
0 TP-04 8.0ft. 19 0.421 0.089 27.0
r Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
1I� Redmond, Washington 98052
Telephone: 425-4 9-4704
Fax: 425-449-4711
PROJECT NUMBER ES-8178
U.S. SIEVE OPENING IN INCHES 1
PROJECT NAME 2nd Place Short Plat
U.S. SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 4 1/23/8 3 4 6 810 1416 20 30 40 50 60 100 140 200
100
95
90
85
80
75
70
65
25 60
w
> 55
m
G✓
w 50
z
w
1-- 45
z
w
40
w
0
35
30
25
20
15
10
5
IELL
il
100 10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL I SAND SILT OR CLAY
coarse fine coarse medium fine
Specimen Identification Classification Cc Cu
TP-05 2.00ft. USDA: Brown Gravelly Sandy Loam, USCS: SNI with Gravel.
Specimen Identification D100 D60 D30 D10 LL PL PI %Silt %Clay
TP-05 Uft. 19 0.643 0.099 1 1 25A
Report ®i*zp A Ution
4. - Southeast
Washington `:1/.
Mr. Kiran Komaravolu
726 Auburn Way North
Auburn, Washington112
� "l •1 11 ■!1 ►•
Earth Solutions NW, LLC
OTHER PERMITS
-� - - -�- � '� =1=1=1
C.S.W.P.P PLAN ANALYSIS AND DESIGN
SECTION IX
BOND QUANTITIES, FACILITY SUMMARIE S
AND DECLARATION OF COVENANT
SECTION X
OPERATIONS AND MAINTENANCE MANUAL
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.3 - DETENTION TANKS AND VAULTS
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash and debris
Any trash and debris which exceed 1 cubic foot
Trash and debris cleared from site.
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
constitute a hazard to County personnel or the
removed according to applicable
public.
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Grass/groundcover
Grass or groundcover exceeds 18 inches in
Grass or groundcover mowed to a
height,
height no greater than 6 inches.
Tank or Vault
Trash and debris
Any trash and debris accumulated in vault or tank
No trash or debris in vault.
Storage Area
(includes floatables and non-floatables).
Sediment
Accumulated sediment depth exceeds 10% of the
All sediment removed from storage
accumulation
diameter of the storage area for '/z length of
area,
storage vault or any point depth exceeds 15% of
diameter. Example: 72-inch storage tank would
require cleaning when sediment reaches depth of
7 inches for more than Y2length of tank.
Tank Structure
Plugged air vent
Any blockage of the vent.
Tank or vault freely vents.
Tank bent out of
Any part of tank/pipe is bent out of shape more
Tank repaired or replaced to design.
shape
than 10% of its design shape.
Gaps between
sections, damaged
A gap wider than Yz-inch at the joint of any tank
sections or any evidence of soil particles entering
No water or soil entering tank
through joints or walls,
joints or cracks or
the tank at a joint or through a wall,
tears in wall
Vault Structure
Damage to wall,
Cracks wider than'/ -inch, any evidence of soil
Vault is sealed and structurally
frame, bottom, and/or
entering the structure through cracks or qualified
sound,
top slab
inspection personnel determines that the vault is
not structurally sound.
Inlet/Outlet Pipes
Sediment
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than '/-inch at the joint of the
No cracks more than Y<-inch wide at
inlet/outlet pipes or any evidence of soil entering
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
2021 Surface Water Design Manual —Appendix A
A-5
7/23/2021
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO, 3 - DETENTION TANKS AND VAULTS
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Access Manhole
Cover/lid not in place
Cover/lid is missing or only partially in place.
Manhole access covered.
Any open manhole requires immediate
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools,
not working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
remove
cover/lid after applying 80 Ibs of lift.
reinstalled by one maintenance
person.
Ladder rungs unsafe
Missing rungs, misalignment, rust, or cracks.
Ladder meets design standards.
Allows maintenance person safe
access.
Large access
Damaged or difficult
Large access doors or plates cannot be
Replace or repair access door so it
doors/plate
to open
opened/removed using normal equipment.
can opened as designed.
Gaps, doesn't cover
Large access doors not flat and/or access
Doors close flat; covers access
completely
opening not completely covered.
opening completely.
Lifting Rings missing,
Lifting rings not capable of lifting weight of door
Lifting rings sufficient to lift or
rusted
or plate.
remove door or plate.
7/23/2021 2021 Surface Water Design Manual —Appendix A
A-6
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.4 - CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Cleanout gate is not watertight.
Gate is watertight and works as
designed.
Gate cannot be moved up and down by one
Gate moves up and down easily and
maintenance person.
is watertight.
Chain/rod leading to gate is missing or damaged.
Chain is in place and works as
designed.
Orifice Plate
Damaged or missing
Control device is not working properly due to
Plate is in place and works as
missing, out of place, or bent orifice plate.
designed.
Obstructions
Any trash, debris, sediment, or vegetation
Plate is free of all obstructions and
blocking the plate.
works as designed.
Overflow Pipe
Obstructions
Any trash or debris blocking (or having the
Pipe is free of all obstructions and
potential of blocking) the overflow pipe,
works as designed.
Deformed or
Lip of overflow pipe is bent or deformed.
Overflow pipe does not allow
damaged lip
overflow at an elevation lower than
design
Inlet/Outlet Pipe
Sediment
accumulation
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than 1/2-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
No cracks more than 1/4-inch wide at
the joint of the inlet/outlet pipe,
at the joints of the inlet/outlet pipes.
Metal Grates
(If Applicable)
Unsafe grate opening
Grate with opening wider than inch.
Grate opening meets design
standards.
Trash and debris
Trash and debris that is blocking more than 20%
Grate free of trash and debris,
of grate surface.
Damaged or missing
Grate missing or broken member(s) of the grate.
Grate is in place and meets design
standards.
Manhole Cover/Lid
Cover/lid not in place
Cover/lid is missing or only partially in place.
Cover/lid protects opening to
Any open structure requires urgent
structure.
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
Not Working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
Remove
cover/lid after applying 80 lbs. of lift.
reinstalled by one maintenance
person.
7/23/2021
A-8
2021 Surface Water Design Manual —Appendix A
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.5 - CATCH BASINS AND MANHOLES
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Structure
Sediment
Sediment exceeds 60% of the depth from the
Sump of catch basin contains no
bottom of the catch basin to the invert of the
sediment.
lowest pipe into or out of the catch basin or is
within 6 inches of the invert of the lowest pipe
into or out of the catch basin.
Trash and debris
Trash or debris of more than cubic foot which
is located immediately in front of the catch basin
No Trash or debris blocking or
potentially blocking entrance to
opening or is blocking capacity of the catch basin
catch basin,
by more than 10%.
Trash or debris in the catch basin that exceeds
No trash or debris in the catch basin.
1/3 the depth from the bottom of basin to invert
the lowest pipe into or out of the basin.
Dead animals or vegetation that could generate
No dead animals or vegetation
odors that could cause complaints or dangerous
present within catch basin.
gases (e.g., methane).
Deposits of garbage exceeding 1 cubic foot in
No condition present which would
volume.
attract or support the breeding of
insects or rodents.
Damage to frame
Corner of frame extends more than inch past
Frame is even with curb.
and/or top slab
curb face into the street (If applicable).
Top slab has holes larger than 2 square inches or
Top slab is free of holes and cracks.
cracks wider than'/4 inch.
Frame not sitting flush on top slab, i.e.,
Frame is sitting flush on top slab,
separation of more than % inch of the frame from
the top slab.
Cracks in walls or
bottom
Cracks wider than '% inch and longer than 3 feet,
any evidence of soil particles entering catch
Catch basin is sealed and is
structurally sound,
basin through cracks, or maintenance person
judges that catch basin is unsound.
Cracks wider than'/2 inch and longer than 1 foot
No cracks more than 1/4 inch wide at
at the joint of any inlet/outlet pipe or any evidence
the joint of inlet/outlet pipe,
of soil particles entering catch basin through
cracks.
Settlement/
Catch basin has settled more than 1 inch or has
Basin replaced or repaired to design
misalignment
rotated more than 2 inches out of alignment.
standards.
Damaged pipe joints
Cracks wider than at the joint of the
inlet/outlet pipes or any evidence of soil entering
No cracks more than'/ -inch wide at
the joint of inlet/outlet pipes,
the catch basin at the joint of the inlet/outlet
pipes.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint,
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Inlet/Outlet Pipe
Sediment
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than'/z-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
No cracks more than'/ -inch wide at
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
2021 Surface Water Design Manual —Appendix A
I�
7/23/2021
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.5 - CATCH BASINS AND MANHOLES
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Metal Grates
(Catch Basins)
Unsafe grate opening
Grate with opening wider than'/8 inch.
Grate opening meets design
standards.
Trash and debris
Trash and debris that is blocking more than 20%
Grate free of trash and debris.
of grate surface.
Damaged or missing
Grate missing or broken member(s) of the grate.
Grate is in place and meets design
Any open structure requires urgent
standards.
maintenance.
Manhole Cover/Lid
Cover/lid not in place
Cover/lid is missing or only partially in place.
Cover/lid protects opening to
Any open structure requires urgent
structure.
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
Not Working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
Remove
cover/lid after applying 80 lbs. of lift.
reinstalled by one maintenance
person.
7/23/2021
2021 Surface Water Design Manual —Appendix A
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.6 - CONVEYANCE PIPES AND DITCHES
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Pipes
Sediment & debris
Accumulated sediment or debris that exceeds
Water flows freely through pipes.
accumulation
20% of the diameter of the pipe.
Vegetation/roots
Vegetation/roots that reduce free movement of
Water flows freely through pipes.
water through pipes.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint,
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to protective
Protective coating is damaged; rust or corrosion
Pipe repaired or replaced.
coating or corrosion
is weakening the structural integrity of any part of
pipe.
Damaged
Any dent that decreases the cross section area of
Pipe repaired or replaced,
pipe by more than 20% or is determined to have
weakened structural integrity of the pipe.
Ditches
Trash and debris
Trash and debris exceeds 1 cubic foot per I,000
Trash and debris cleared from
square feet of ditch and slopes.
ditches.
Sediment
accumulation
Accumulated sediment that exceeds 20% of the
design depth.
Ditch cleaned/flushed of all sediment
and debris so that it matches design.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
constitute a hazard to County personnel or the
removed according to applicable
public.
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint,
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vegetation
Vegetation that reduces free movement of water
Water flows freely through ditches.
through ditches.
Erosion damage to
Any erosion observed on a ditch slope.
Slopes are not eroding.
slopes
Rock lining out of
One layer or less of rock exists above native soil
Replace rocks to design standards,
place or missing (If
area 5 square feet or more, any exposed native
Applicable)
soil.
2021 Surface Water Design Manual —Appendix A
7/23/2021
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.30 - PERMEABLE PAVEMENT BMP
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Preventative
Surface cleaning/
Media surface vacuumed or pressure washed
No dirt, sediment, or debris clogging
vegetation control
annually, vegetation controlled to design
porous media, or vegetation limiting
maximum. Weed growth suggesting sediment
infiltration.
accumulation.
Porous Concrete,
Trash and debris
Trash and debris on the pavement interfering
No trash or debris interfering with
Porous Asphaltic
with infiltration; leaf drop in fall season.
infiltration.
Concrete, and
Permeable Pavers
Sediment
Sediment accumulation on the pavement
Pavement infiltrates as designed;
accumulation
interfering with infiltration; runoff from adjacent
adjacent areas stabilized.
areas depositing sediment/debris on pavement.
Infiltration rate
Pavement does not infiltrate at a rate of 10
Pavement infiltrates at a rate greater
inches per hour.
than 10 inches per hour.
Ponding
Standing water for a long period of time on the
Standing water infiltrates at the
surface of the pavement.
desired rate.
Broken or cracked
Pavement is broken or cracked.
No broken pavement or cracks on
pavement
the surface of the pavement.
Settlement
Uneven pavement surface indicating settlement
Pavement surface is uniformly level.
of the subsurface layer.
Moss growth
Moss growing on pavement interfering with
No moss interferes with infiltration.
infiltration.
Inflow
Inflow to the pavement is diverted, restricted, or
Inflow to pavement is unobstructed
depositing sediment and debris on the
and not bringing sediment or debris
pavement,
to the pavement.
Underdrain
Underdrain is not flowing when pavement has
Underdrain flows freely when water
been infiltrating water,
is present.
Overflow
Overflow not controlling excess water to desired
Overflow permits excess water to
location; native soil is exposed or other signs of
leave the site at the desired location;
erosion damage are present.
Overflow is stabilized and
appropriately armored.
Permeable Pavers
Broken or missing
Broken or missing paving blocks on surface of
No missing or broken paving blocks
pavers
pavement,
interfering with infiltration.
Level surface
Uneven surface due to settlement or scour of fill
Pavement surface is uniformly level.
in the interstices of the paving blocks.
Compaction
Poor infiltration due to soil compaction between
No soil compaction in the interstices
paving blocks.
of the paver blocks limiting
infiltration.
Dead grass
Grass in the interstices of the paving blocks is
Healthy grass is growing in the
dead.
interstices of the paver blocks.
Inspection
Frequency
Annually and after large storms, and as needed
Permeable pavement is functioning
seasonally to control leaf drop, evergreen
normally,
needles etc.
7/23/2021
2021 Suiiace Water Design Manual —Appendix A
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NOm 35 - SPLASH BLOCK BMP
Maintenance
Component
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Maintenance is Performed
Site
Trash and debris
Trash and debris accumulated on the splash
block.
Splash block site free of any trash or
debris.
Splash Block
Dislodged
Splash block moved from outlet of downspout.
Splash block correctly positioned to
catch discharge from downspout.
Channeling
Water coming off the splash block causing
erosion.
No erosion occurs from the splash
block.
Downspout water
misdirected
Water coming from the downspout is not
discharging to the dispersal area.
Water is discharging normally to the
dispersal area.
Inspection
Frequency
Annually and after large storms.
Rain harvesting equipment is
functioning normally.
2021 Smface Water Design Manual —Appendix A
7/23/2021