HomeMy WebLinkAboutMisc''
City of l'f ent
Planning Div/sio~n
FEB -6 2013
26TH SHORl IPlAl
TECHNICAL INFORMATION REPORT
TARGETED DRAINAGE REVIEW
February 4, 2013
JOB NO, 258-040-012
Prepared for
Conner Homes
846 1081h Avenue NE
Bellevue. WA 98004
Submitted by
ESM Consulting Engineers. LLC
33400 8'h Avenue South
Suite 205
FederalVVay. VVA 98003
253.838.6113 tel
253.838.7104 fax
www.esmcivil.com
February 4, 2013
TECHNICAL INFORMATION REPORT
FOR
26TH SHORT PLAT
Prepared for:
Conner Homes
846 1 081h Avenue NE
Bellewe, WA 98004
Prepared by:
ESM Consultlng Engineers
33400 81h Avenue South
Suite 210
Federal Way, WA 98003
l\esm8\engrlesm-jobs\258\040\0121document\rprt-001.docx
Job No. 258-040-012
TABLE OF CONTENTS
1. Project Overview................................................................................................................................................. 1
2. Conditions and Requirements Summary.............................................................................. 10
3. Offsite Analysis................................................................................................................................................... 12
4. Flow Control and Water Quality Facility Analysis and Design....................... 12
5. Conveyance System Analysis and Design.......................................................................... 12
6. Special Reports and Studies............................................................................................................... 12
7. Other Permits......................................................................................................................................................... 12
8. CSWPPP Analysis and Design.......................................................................................................... 12
9. Bond Quantities, Facility Summaries, and Declaration of Covenant...... 15
10. Operations and Maintenance Manual...................................................................................... 15
Appendices
Appendix A
Appendix B
Appendix C
Geotechnical Report
TESC BMP Details
Roof Infiltration Detail
1. PROJECT OVERVIEW
The 25th Short Plat project is a proposed 3-lot single family short plat The project is
situated in the NW Quarter of Sections 5, Township 23 North, Range 5 East W.M., King
County. This project is located in King County within City of Renton. The King County
parcel identification number is 52305-9023. Refer to Figure 1 for the TIR Worksheet and
Figure 2 for the Vicinity Map. The site address is 1311 North 25th Street, Renton WA 98057.
The property is currently one lot with a single family residence. The site is 0.528 acres
which it will be divided into a three lot short plat.
Under the direction from the City Staff, the project will be reviewed under the Small Project
Drainage Review requirements. Due to steep slope found on site, it will require a
Category-1 Targeted Drainage Review outlined in Section 1.1.2.1 of the City of Renton
Amendments to the 2009 King County Surface Water Design Manual (Manual).
The site is in the "Conservation Flow Control Area" for Flow Control Duration Standard. No
detention facilities are proposed for this project because the roof areas will be infiltrated
on each lot This site is also in a "Basic Water Quality Treatment Area" for duration
standard water quality treatment. The site is exempt from water quality treatment facility
because of less than 5,000 square feet of new pollution-generating impervious surfaces
that is not fully dispersed will be added and less than 35,000 square feet of new pollution-
generating pervious surfaces that is not fully dispersed.
The King County Area Soils Survey by the USDA Soils Conservation Services (1973)
generalizes the soils in the vicinity of this project as being predominantly Indianola loamy
fine sand (lnC). Refer to Figure 4 for the Soil Conservation Service Map. Geotechnical
analysis of the site has been conducted by Earth Solutions NW. A copy of the
geotechnical report dated December 2, 2012 is included in Appendix C of this report.
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Project Owner _R_o_b_R_i_s,_·n_g_er ____ _
Phone (425)455-9280
Address 846 108th Ave. NE
Bellevue, WA 98004
Project Engineer _T_re_v_o_r_S_ti_ff ____ _
Company ESM Consulting Engineers
Phone (253) 838-6113
Part 3 TYPE OF PERMIT APPLICATION
0 Landuse Services
Subdivison / Short Subd. / UPD
D Building Services
M/F / Commerical / SFR
D Clearing and Grading
D Right-of-Way Use
D Other
Part 5. PLAN AND REPORT INFORMATION
Technical Information Report
Type of Drainage Review Full~/
(circle): Larges, e
Date (include revision
dates):
Date of Final:
..
Part 6 ADJUSTMENT APPROVALS
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Name North 26th Street Short Plat
ODES Permit# ----------
Location Township _2_3_N ___ _
Range _5_E _____ _
Section 5 -------
Site Address 1311 N. 26th Street, Renton, WA
Part 4 OTHER REVIEWS AND PERMITS
D DFWHPA
0 COE404
[J DOE Dam Safety
D FEMA Floodplain
D COE Wetlands
D Other ---
D Shoreline
Management
D Structural
RockeryNaulU __
D ESA Section 7
Site Improvement Plan (Engr. Plans)
Type (circle one): Full / Modified I
CSmall Site)
Date (include revision
dates):
Date of Final:
Type (circle one): Standard I Complex / Preapplication / Experimental/ Blanket
Description: (include conditions in TIR Section 2)
Date of Aooroval:
2009 Surface Water Design Manual 1-2 l/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes I No Describe:
Start Date:
Completion Date:
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan : _K_e_nn_y_d_a_le _________ _
Special District Overlays:------------------------
Drainage Basin: Lake Washington East
Stormwater Requirements: -----------------------
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS . . .
bl River/Stream ----------
Q Lake
bl Wetlands __________ _
D Closed Depression _______ _
bl Floodplain-----------
0 Other ___________ _
Part 10 SOILS
.
LJ Steep Slope ---------
0 Erosion Hazard _______ _
bl Landslide Hazard --------
0 Coal Mine Hazard -------
0 Seismic Hazard --------
CJ Habitat Protection ______ _
O __________ _
.
Soil Type Slopes Erosion Potential
Indianola loamy fine 4 to 15% Slight
sand (lnC)
Alderwood gravelly 15 to 30%
sandy loam
CJ High Groundwater Table (within 5 feet) D Sole Source Aquifer
D Other D Seeps/Springs
0 Additional Sheets Attached
2009 Surface Water Design Manual 1/9/2009
1-3
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE LIMITATION/ SITE CONSTRAINT
D Core 2 -Offsite Anal~sis
D Sensitive/Critical Areas
D SEPA
D Other
D
D Additional Sheets Attached
Part 12 TIR'SUMMARY SHEET · lnrovide one TIR Summarv Sheet.oar Threshold Discharae Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply)
DischarQe at Natural Location Number of Natural Discharoe Locations:
Offsite Analysis N/A Level: 1 / 2 I 3 dated:
Flow Control N/A Level: 1 / 2 / 3 or Exemption Number
(incl. facilitv summarv sheet\ Small Site BMPs
Conveyance System N/A Spill containment located at:
Erosion and Sediment Control ESC Site Supervisor:
Contact Phone: TBD After Hours Phone:
Maintenance and Operation Responsibility: C Private )I Public
If Private, Maintenance Loa Reauired: Yes~
Financial Guarantees and Provided: Yes I No -
Liabilitv
Water Quality N/A Type: Basic / Sens. Lake / Enhanced Basicm / Bog
(include facility summary sheet) or Exemption No.
Landscaoe Manaaement Plan: Yes I No
Special Requirements las aoolicablel
Area Specific Drainage Type: CDA / SDO I MOP/ BP/ LMP / Shared Fae. I None
Reauirements Name:
Floodplain/Floodway Delineation Type: Major / Minor / Exemption 19
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities Describe: N/ A
Source Control Describe landuse:
(comm./industrial landuse) Describe any structural controls:
2009 Surface Water Design Manual
1-4
1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Oil Control High-use Site: Yes IQ!i)
Treatment BMP:
Maintenance Agreement: Yes / No
with whom?
Other Drainaae Structures
Describe:
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS ·
MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION AFTER CONSTRUCTION
D Clearing Limits D Stabilize Exposed Surfaces
D Cover Measures D Remove and Restore Temporary ESC Facilities
D Perimeter Protection D Clean and Remove All Silt and Debris, Ensure
D Traffic Area Stabilization Operation of Permanent Facilities
0 Sediment Retention D Flag Limits of SAO and open space
D Surface Water Collection
preservation areas
0 Other 0 Dewatering Control
D Dust Control
Q Flow Control
Part 14 STORMWATER FACILITY DESCRIPTIONS /Note: Include Facilitv Summarv and Sketchl
Flow Control T"ne/Descriotion Water Qualitv Tvne/Descriotion
Q Detention D Biofiltration
0 Infiltration Trench D Wetpool
CJ Regional Facility Q Media Filtration
D Shared Facility D Oil Control
D Flow Control D Spill Control
BMPs D Flow Control BMPs
D Other D Other
2009 Surface Water Desib'!l Manual 1-5 1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
,•
Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS
D Drainage Easement D Cast in Place Vault
D Covenant 0 Retaining Wall
D Native Growth Protection Covenant D Rockery> 4' High
D Tract D Structural on Steep Slope
D Other D Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER · ,.
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this w ksheet and the attached Technical Information Report. To the best of my
kno 1n orm n provided here is accurate.
2009 Surface Water Design Manual
1-6
1/9/2009
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Figure 4 -Soils
Cqlenian Pain ..
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Soil types on site:
AgD
lnC
Alderwood gravelly sandy loam
Indianola loamy fine sand
·:,. ,• . . ' ' ... . . . . . : ... • •
15-30% slopes
4-15% slopes
9
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2. CONDITIONS AND REQUIREMENTS SUMMARY
There have been no preliminary approval conditions for this project
Review of Eight Core Requirements & Six Special Requirements
The proposed project has been reviewed in accordance with the Core and Special
Requirements in Sections 1.2 and 1.3 of the Manual. Since there will be over 7,000 square
feet of land disturbing activity and the site is adjacent to steep slope hazard area
therefore; A Targeted Drainage Review (TOR) under Project Category 1 will be required. A
TDR requires that the project complies with the following requirements:
• Core Requirement #1: Discharge at the Natural Location, Section
• Core Requirement #5: Erosion and Sediment Control, Section
• Special Requirement #1: Other Adopted Area-Specific Requirements
• Special Requirement #2: Floodplain/Floodway Analysis
• Special Requirement #3: Flood Protection Facilities
• Special Requirement #4: Source Control
• Special Requirement #6: Aquifer Protection Area
Although not required for the TOR, this TIR will also address these requirements:
• Core Requirement #3: Flow Control
Core Requirement No. 1 Discharge at the Natural Locatjon
The roof runoff will be discharged through individual lot infiltration trenches.
Core Requirement No. 2 -Offsite Analysis
Not required for TDR
Core Requirement No. 3 -Flow Control
A flow control facilities is not required for TDR. The project site is proposing to utilize
Single Family Roof Downspout Infiltration Trenches based on City of Renton Standard Plan
225.20.
Core Requirement No. 4 Conveyance System
Not required for TDR
Core Requirement No. 5 Temporary Erosion and Sedimentation Control
All proposed projects that will clear, grade, or otherwise disturb the site must provide
erosion and sediment controls to prevent, to the maximum extent practicable, the transport
of sediment from the project site to downstream drainage facilities, water resources, and
adjacent properties. To prevent sediment transport as well as other impacts related to
IO
land-disturbing activities, Erosion and Sediment Control (ESC) measures that are
appropriate to the project site must be applied as described in Section 1.2.5.1 and shall be
implemented consistent with the requirements in Section 1.2.5.3 that apply to the
proposed project.
A copy of the grading and ESC plans and notes are included in Section 8 of this report.
Core Requirement No. 6 -Maintenance and Operations
Not required for TOR
Core Requirement No. 7 -Financial Guarantees and Liability
Not required for TOR
Core Requirement No. 8 -Water Quality
Not required for TOR
Special Requirement No. 1 -Other Adopted Area-Specific Requirements
The project is located within the Lake Washington East drainage basin. It does not
appear to be any specific requirements for this project's downstream path.
Special Requirement No. 2 -Floodplain/Floodway Delineation
This project is not within a floodplain or floodway.
Special Requirement No. 3 -Flood Protection Facilities
This requirement does not apply since the project is outside any defined floodplains.
Special Requirement No. 4 -Source Controls
This project does not propose a commercial building or commercial site development
permit; therefore additional source controls are not needed.
Special Requirement No. 5 -Oil Control
The project does not contain any high use areas; therefore additional oil control measures
are not needed.
Special Requirement No. 6 -Aquifer Protection Area
The project is in Zone 2 of the Aquifer Protection Area. Only clean roof runoff will be
infiltrated, therefore no facility liners are required.
11
3. OFFSITE ANALYSIS
Not required for Targeted Drainage Review.
4. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS & DESIGN
Not required for Targeted Drainage Review.
5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN
Not required for Targeted Drainage Review.
6. SPECIAL REPORTS AND STUDIES
• Geotechnical Report by Earth Solutions NW LLC, dated December 4, 2012.
A copy is provided in Appendix B of this report.
7. OTHER PERMITS
Other permits may be needed.
8. TESC ANALYSIS AND DESIGN
The Temporary Erosion and Sediment Control (TESC) Plan is shown on sheets GR-01 and
GR-02 of the construction plan set The TESC Plan was developed in accordance with the
criteria in Section 1.2.5.1 and Appendix D of the 2009 King County Stormwater Drainage
Manual. A copy of the grading and TESC plans and notes are included in this section.
The site also receives very little offsite flows. The erosion control plan consists of installing
silt fence around the perimeter of the site, and grading a ditch to intercept flow and
prevent it from running down steep slopes to minimize any runoffs. Catch basin filters will
also installed in the catch basins during construction to minimize the amount of sediment
that will enter the existing storm drainage system. The majority of the site will be cleared
prior to site grading, although no clearing or grading will occur on the steep slopes on the
western portion of the site.
Construction activities will include site preparation, TESC installation and site-wide grading.
The scheduling for these activities will be determined after plan approval.
The following BMPs will be used during the site grading activities. Further description of
the BMPs from the Manual is included in this section.
BMP 214.00 -Silt Fence
BMP 216.30 -Catch Basin Filter
BMP details are presented in Appendix C.
12
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CO,iCEPlUAI. GRADN3 Pl.AN
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9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF
COVENANT
The Bond Quantities and Declaration of Covenant are not required for Targeted Drainage
Review.
10. OPERATIONS AND MAINTENANCE MANUAL
Not required for Targeted Drainage Review
15
9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF
COVENANT
The Bond Quantities and Declaration of Covenant are not required for Targeted Drainage
Review.
10. OPERATIONS AND MAINTENANCE MANUAL
Not required for Targeted Drainage Review
15
APPENDiXA
Geotechnical Report
,-------
Geo technical Engi neering
Geology
Environmenta l Scientists
Co nstruction Monitoring
GEOTECHN ICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLAT
1311 NORTH 26TH STREET
RENTON , WASHINGTON
ES-2590
PREPARED FOR
CONNER HOMES
December 4, 2012
Kyle R. Campbell, P.E.
Principal
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLAT
1311 NORTH 26™ STREET
RENTON, WASHINGTON
ES-2590
Earth Solutions NW, LLC
1805-136th Place Northeast, Suite 201, Bellevue, Washington 98005
Ph: 425-449-4704 Fax: 425-449-4711
Toll Free: 866-336-8710
Geotechnlcal Engineering Report
Geotecbnlcal Services ire Performed lor
UpeclDc Purposes, PBl'IIDll8, and ProjeCt8
Geotechnical engineers structure their services to meet the specific needs of
their clients. A geotechnical engineering study conducted for a civil engi-
neer may not fulfill the needs of a construction contractor or even another
civil engineer. Because each geotechnical engineering study is unique, each
geotechnicaf engineering report Is unique, prepared solely for the client. No
one except you should rely on your geotechnical engineering report without
first conferring with the geotechnical engineer who prepared it. And no one
-not even you-should apply the report for any purpose or project
except the one originally contemplated.
llleallll llie !FUii RepmiR
Serious problems have occurred because those relying on a geotechnical
engineering report did not read it all. Do not rely on an executive summary.
Do not read selected elements only.
lil Geoteclmll:al Engineering Report Us Baseall on
Iii Unique Set DI Pl'Oject-Spaclllc IFactol's
Geotechnical engineers consider a number of unique, project-specific fac-
tors when establishing the scope of a study. Typical factors include: the
client's goals, objectives, and risk management preferences: the general
nature of the structure Involved, its size, and configuration: the location of
the structure on the site: and other planned or existing site improvements,
such as access roads, parking lots, and underground utilities. Unless the
geotechnical engineer who conducted the study specifically indicates oth-
erwise, do not rely on a geotechnical engineering report that was:
o not prepared for you,
o not prepared for your project,
o not prepared for the specific site explored, or
o completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those that affect:
0 the function of the proposed structure, as when it's changed from a
parking garage to an office building, or from a light industrial plant
to a refrigerated warehouse,
o elevation, configuration, location, orientation, or weight of the
proposed structure,
0 composition of the design team, or
o project ownership.
As a general rule, a/vmys inform your geotechnical engineer of project
changes-even minor ones-ruid request an assessment of their impact.
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider deVBlopments of which
they were not informed.
Subsurface Candillons can Cliange
A geotechnical engineering report is based on conditions that existed at
the time the study was performed. Do not rely on a geotechnical engineer-
ing repartwhose adequacy may have been affected by: the passage of
time: by man-made events, such as construction on or adjacent to the site:
or by natural events, such as floods, earthquakes, or groundwater fluctua-
tions. Alw.iys contact the geotechnical engineer before applying the report
to determine if it is still reliable. A minor amount of additional testing or
analysis could prevent major problems.
iVIDBI Geotechnlcal Flmllnllll Are Prol11181onal --Site exploration identtties subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnicat engi-
neers review field and laboratory data and then apply their professional
judgment to render an opinion about subsurtace conditions throughout the
site. Actual subsurtace conditions may differ-;;ometimes significantly--
from those indicated in your report. Retaining the geotechnical engineer
who developed your report to provide construction observation is the
most effective method of managing the risks associated with unanticipated
conditions.
ft Report's Recommendations lire Not Rnal
Do not overrely on the construction recommendations included in your
report. Those recommendations are not final, because geotechnical eng~
neers develop them principally from judgment and opinion. Geotechnical
engineers can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnica/
engineer who developed your report cannot a~ume responsibility or
liability tor the report's recommendallons if that engineer does not pedorm
cons/Ille/ion observation.
A Geotechnlcal Engineerinu Report Is SUb.lect tu
Misinterpretation
Other design team members' misinterpretation of geotechnical engineering
reports has resulted in costly problems. Lower that risk by having your geo-
technical engineer confer with appropriate members of the design team after
submitting the report. Also retain your geofechnical engineer to review perti-
nent elements of the design team's plans and specifications. Contractors can
also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconstruction
conferences, and by providing construction observation.
IIDO l\lD1t R&dl'l!lll lh81EqinB&r'II ILoD8
Geotechnical engineers prepare final boring and testing logs based upon
their interpretation of field logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating logs from lh8 report can elevats risk.
llb!I COidNa:t®rs III Co111811ete llepoft and
l!hdullance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly problems, give con-
tractors the complete geotechnical engineering report, butpreface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the
report's accuracy is limited; encourage them to confer with the geotechnlcal
engineer who prepared the report (a modest fee may be required) and/or to
conduct addltlonal study to obtain the specific types of Information they
need or prefer. A pre bid conference can also be valuable. Be sure contrac-
tors have sufficient time to pertorm additional study. Only then might you
be in a position to give contractors the best information available to you,
while requiring them to at least share some of the financial responsibillties
stemming from unanticipated conditions.
lllnd Re111111nalllllll!f IPl'ovlslons Clusei!.f
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineering disci-
plines. This lack ol understanding has created unrealistic expectations that
have led to disappointments, claims, and disputes. To help reduce the risk
of such outcomes, geotechnical engineers commonly. include a variety of
explanatory provisions in their reports. Sometimes labeled '!Imitations'
many of these provisions Indicate where geotechnlcal engineers' responsi-
bilities begin and end, to help others recognize their own responsibilities
and risks. Read these provisions closely. Ask questions. Your geofechnical
engineer should respond fully and frankly.
1B11oanvlromnentai concerns Are Not Covarad
The equipment. techniques. and personnel used to pertorm a geoenviron-
mental study differ significantly from those used to pertorm a geotechnical
study. For thal reason, a geotechnical engineering report does not usually
relate any geoenvironmental findings, conclusions, or recommendations;
e.g., about the likelihood of encountering underground storage tanks or
regulated contaminants. Unanlicipated environmental problems have led
to numerous project failures. ti you have not yet otrtained your own geoen-
vironmental information, ask your geotechnical consultant for risk man-
agement guidance. Do not rely on an environmental report prepared for
someone else.
Glbtaln Prohlnlml liBSlllt8l!JCe To Deal wllh lt/lDld
Diverse strategies can be applied during building design, construction,
operation, and maintenance to prevent significant amounts of mold from
growing on indoor surtaces. To be effective, all such strategies should be
devised for the express purpose of mold prevention, integrated into a com-
prehensive plan, and executed with diligent oversight by a professional
mold prevention consultant. Because just a small amount of water or
moisture can lead to the development of severe mold infestations, a num-
ber of mold prevention strategies focus on keeping butlding surfaces dry.
While groundwater, water Infiltration, and similar issues may have been
addressed as part of the geotechnical engineering study whose findings
are conveyed in-this report, the geotechnical engineer in charge of this
project Is not a mold prevention consultant none of the servfCIIS per-
formed In canner:tlan with the geat11chnl,:af engfneer's study
wem d1111lgned or candut:18d far the purpose al maid pmvsn-
1/an. Proper Implementation ut the fll&Ommendallons C011111Jyed
In this report wt/I not of llstl« be sufficient to prevent maid from
growing In or an the strut:lum Involved.
t:lm1U:: Yollf AIIFE-Mambei' Gaotachnclal
I' ror Add111DIIIII A1181sbtnce
Membership in ASFE/The Best People on Earth exposes geotechnical
engineers to a wide array of risk management techniques that can be of
genuine benefit for everyone involved with a construction project. Confer
with you I\SFE-member geofechnical englnoor for more infonnation.
A5FE
·1bai ·ooil .e·1oa1a oD, llitb
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone: 301/565-2733 Facsimile: 301/589-2017
e-mail: info@asfe.org www.asfe.org
Copyrl(Jht 2004 by ASFE, Inc. Ouplfcatlon, mproductlan, or copytna of this documsn~ In whoill or In pa,r. by any means whatsosver; Is strlctly prohibited, BXCBpt with ASFE)
spBcfflC written permission. Exclrpting, quotfng, or otherwlsB utracting wording from this document Is permitted only with th, ,xpress wrlttan perm/sSlon of ASFE. and only for
purposes of scholdrly re66arch or boolc twlaw. Only mtJmbers of ASFE may usB this docurmmt as a comp/ernfnt to or as an elelTlfflt of a geotschnlcaJ enointefing report. Any oth11r
firm, lndfvldual, or othsr entfty that so uses this document without being an ASFE member could b8 commlttiflQ m1gl/gent or lntsntional (fraudulent) misn,presffltl.tion.
IIGER06045.0M
December 4, 2012
ES-2590
Conner Homes
846-108th Avenue Northeast
Bellevue, Washington 98004
Attention: Mr. Rob Risinger
Dear Mr. Risinger:
Earth Solutions NW LLC
• Geotcchnical Engineering
• Construction Monitoring
• Environmental Sciences
Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical
Engineering Study, Proposed Residential Short Plat, 1311 North 26th street, Renton,
Washington". We understand the site will be subdivided into three or four detached residential
lots and associated improvements.
In our opinion, provided the recommendations of this study are incorporated into the final
design, construction of the residential structures is feasible from a geotechnical standpoint.
Based on the expected subsurface conditions, the proposed building structures can be
supported on conventional continuous and spread footing foundations bearing on medium
dense native soils (where encountered), or at least 18 inches of suitable site soil compacted to
structural fill specifications.
Recommendations for site excavations, foundation subgrade preparation, foundation design
and other pertinent geotechnical recommendations are provided in this study.
The opportunity to be of service to you is appreciated. If you have any questions regarding the
content of this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
1805 -136th Place N.E., Suite 201 • Bellevue, WA 98005 • (425) 449-4704 • FAX (425) 449-4711
INTRODUCTION
TABLE OF CONTENTS
ES-2590
... · ............................... -.~ .. ; ... ;; ... ; ........... ,· ............. ..
PAGE
1
General ............................................................. ,,.. ... .. ... ... 1
Project Description .......................................................... , 1
Surface .................... , ......... , ............. ,............................... 2
Subsurface ........................ -.-............................................... 2
Groundwater ............................. , .. , ....... ,............................ 2
CRITICAL AREAS ASSESSMENT.................................................. 3
Erosion Hazards ..................................... , ................ ,, ........ ,, 3
Landslide· Hazards............................................................. 3
Steep Slope Hazards ........................... ,, ......... , .. _.................. 3
Foundation Setbacks, ....................................•.....•...••......... 4
DISCUSSION AND RECOMMENDATIONS....................................... 4
.
General.. .................................................... ,................ .. . ... 4
Site Preparation and Earthwork ....... , .................................... 4
Temporary Erosion Control.. ............................ , .......... 5
Expected Sequence of Earthwork ... , .... .;.................... 5
Foundation Subgrade Preparation.............................. 5
Structural Fill .............................. , ... ,., ........ _............. 6
Foundations ........................................................ -.. · .• ·......... 7
Retaining Walls ................................................ _. ............... ,. 7
Slab-on-Grade Floors ....... , ...... , ......... _ ...... , ............... ,........... 8,
Drainage ........................... , .............. -.................................. 8
Excavations and Slopes ................................. _ .. _ . ., ............. 9
Seismic Considerations ............... ,........................................ 9
Utility Support and Trench Backfill. ......................... ,........... 9
LIMITATIONS ....................... · ...... ,, ........................... ,, .............. _,....... 10
_Additional Services ............................. ,.............................. 10
Earth Solutions NW, LLC
GRAPHICS
PLATE1
PLATE2
PLATE 3
PLATE4
APPENDICES
Appendix A
Appendix B
TABLE OF CONTENTS
Cont'd
ES-2590'
VICINITY MAP
TEST PIT LOCATION PLAN
RETAINING WALL DRAINAGE DETAIL
FOOTING DRAIN DETAIL
Subsurface Exploration
Test Pit Logs
Laboratory Test Results
Eerth,Solullons NW, LLC
General
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLA
1311 NORTH 26TH STREET
RENTON, WASHINGTON
ES-2590
INTRODUCTION
This geotechnical engineering study was prepared for the proposed residential short plat to be
constructed in the lower Kennydale neighborhood of Renton, Washington. The approximate
location of the site is illustrated on the Vicinity Map (Plate 1 ). The purpose of this study was to
develop geotechnical recommendations for the proposed project. The scope of services for
completing this geotechnical engineering study included the following:
o conduct subsurface explorations to characterize the soil and groundwater conditions;
o Performing engineering analyses, and;
o Preparation of this geotechnical engineering study.
As part of preparing this study, the following documents and resources were reviewed:
o The City of Renton Critical Areas Regulations.
o Geologic Map of the Renton Quadrangle, King County, Washington.
o USDA NRCS Web Soil Survey GIS database.
Project Description
We understand the property will be subdivided into three or four detached residential projects.
The approximate limits of the proposed development are illustrated on the Test Pit Location
Plan (Plate 2). Based on existing topography, grading will likely be limited to establishing
subgrade elevations for the new residential structures.
The proposed building construction will likely consist of relatively lightly-loaded wood frame
construction supported on conventional foundation systems. At the time this report was
prepared, specific building load values were not available. However, based on our experience
with similar developments, we anticipate perimeter wall loads of approximately 1 to 2 kips per
lineal foot and slab on grade loading on the order of 150 pounds per square foot.
Conner Homes
December 4, 2012
ES-2590
Page 2
If the above design estimates are incorrect or change, ESNW should be contacted to review the
recommendations in this report. ESNW should review the final design to verify that our
geotechnical recommendations have been incorporated into the final design.
Surface
The subject site is located in the southeastern corner of the intersection between North 25th
Street and Park Place North in the Lower Kennydale neighborhood of Renton, Washington.
The approximate location of the site is illustrated on the Vicinity Map (Plate 1 ). The property is
bordered to the north by North 26th Street, to the south and east by existing residential parcels
and to the west by Park Place North. The eastern margin of the site is currently occupied by a
residence and landscaped with lawn and areas of sparse vegetation. Topography is relatively
level across the approximate western 213rd of the site where the new lots will be created. A
slope descends from the west and north property boundaries to the rights-of-way and from the
south to the adjacent residential property, creating an elevated pad configuration.
Subsurface
A representative of ESNW observed, logged and sampled four test pits advanced within
accessible areas of the subject site for purposes of characterizing and classifying the site soils.
The test pits were excavated using a backhoe and operator provided by the client. Please refer
to the test pit logs provided in Appendix A for a more detailed description of the subsurface
conditions. The approximate test pit locations are illustrated on the Test Pit Location Plan
(Plate 2).
Underlying the topsoil, loose to medium dense silty sand fill (Unified Soil Classifications SM)
was encountered extending to depths of about two and one-half feet at test pit location TP-3 to
about 10.5 feet at test pit location TP-2 and about 12 feet at test pit location TP-1. Underlying
the fill, medium dense to dense silty sand and sand (SM and SP-SM) was encountered
extending to the maximum exploration depth of 12.5 feet below existing grade. The fill
contained only trace amounts of deleterious debris such as asphalt pieces and was generally
consistent from a textural standpoint.
The referenced Geologic Map identifies glacial till (Qvt) and advance outwash (Qva) across the
site and immediately surrounding areas. The native soils encountered at the test pit locations
are generally consistent with the soils within the transition zone between glacial till and advance
outwash deposits.
Groundwater
Groundwater seepage was not encountered at the time of exploration (November 2012).
Perched groundwater seepage zones are common along the contact between permeable soils
such as sand and lower permeability soils such as silt and clay. Groundwater seepage,
however, could be encountered locally within deeper excavations throughout the site, such as
the planned parking area excavation. 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 flow rates are higher during the wetter, winter months.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
CRITICAL AREAS ASSESSMENT
ES-2590
Page 3
As part of our report preparation, we assessed the site for potential instability relating to steep
slopes, landslide hazards and erosion hazards. We reviewed the online COR Map database on
the City of Renton website. Based on review of the GIS database, erosion hazard areas are
located on the western portion of the subject site, regulated slopes are mapped on portions of
the west property and landslide hazards are mapped on the eastern approximately one-half of
the property. Renton critical area regulations, Code Section 4-3-050 were reviewed as part of
this assessment.
Erosion Hazards
Erosion hazards were delineated along the steeper sloped areas of the site, generally along the
western margins. The USDA NRCS online resource indicates the approximate western one-
third of the site is underlain by Alderwood series (AgC) glacial till, 15 to 30 percent slopes and
the remainder of the site is underlain by Indianola (lnC) soils. The topography in this area
consists of a slope which descends from the existing yard area to Park Place North and North
25th Street. The slope ranges in height from about four feet and increases to the west to about
15 feet, with slope gradients generally in excess of 40 percent. The soils which comprise the
slope consist primarily of loose to medium dense silty sand and sand fill. We understand
grading in this area will be limited to establishing adequate foundation support. We understand
any grading along the steeper sloped areas of the site will be limited to enhancing stability by
removing yard waste and establishing more appropriate vegetation. In this respect, the project
envelope will be located outside the erosion hazard delineation and standard erosion and
sediment control BMPs will provide an adequate level of safety.
Landslide Hazards
The slopes along the south, west and part of the north property boundary are inclined at more
than 40 percent and range in height up to about 15 feet. Based on the conditions encountered
at the test pits in this area (TP-1, TP-2 and TP-4) the soils underlying the slope consist of
granular fill. Medium dense conditions were generally encountered at depths of about four to
five feet. In our opinion, the slopes would present a low landslide hazard. Final grading plans
must prevent water from ponding or flowing over the sloped areas of the site. With respect to
the mapped landslide hazard area, given the low existing topographic relief in the eastern one-
half of the site, this area would be considered a low landslide hazard.
Steep Slope Hazards
Based on review of the Renton Critical Areas maps, the descending slope bordering the south,
west and portions of the north property are mapped as Protected Slopes. The slopes were
created during past grading activities which consisted of placing fill to raise the site grades to
the current configuration and construction of the current rights-of-way alignments. We
understand no grading will take place on the protected slope areas other than possibly
revegetation.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
Foundation Setbacks
ES-2590
Page4
In our opinion, new foundations should maintain a minimum setback of 15 feet from the top of
the descending slopes located along the south, west and north sides of the site. Fill should not
be placed between the foundations and the slopes. Decks may be placed between the new
foundations and top of descending sloped provided the foundations are drilled (to minimize
disturbance) and extend to a depth of at least ten feet. Property survey information was not
available at the time of this report, but in any case, foundation elements should not be placed
on the descending slope.
ESNW should review the final plans to confirm the recommendations and intent of this report
are followed and to provide additional recommendations.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our study, construction of the proposed residential short plat project is
feasible from a geotechnical standpoint. The primary geotechnical considerations associated
with the proposed development include excavation for the new residences, temporary slope
construction, foundation subgrade preparation and related earthwork for the building areas, and
protecting the sloped areas of the site. Open cut excavations for purposes of facilitating
construction of the new residential structures are feasible, in our opinion. Due to the presence
of fill, overexcavation of the existing fill will be necessary as part of preparing the foundation
subgrade for the building structures. Where existing fill, loose native soil, or otherwise
unsuitable conditions are present at subgrade elevations, the minimum structural fill depth
below foundations should be 24 inches. Recommendations for preparing the building
foundation subgrade and other pertinent geotechnical recommendations are provided in the
following sections of this report.
This geotechnical engineering study has been prepared for the exclusive use of Conner Homes
and their representatives. The study has been prepared specifically for the subject project. No
warranty, expressed or implied, is made. This study has been prepared in a manner consistent
with the level of care and skill ordinarily exercised by other members of the profession currently
practicing under similar conditions in this area.
Site Preparation and Earthwork
The primary geotechnical considerations with respect to earthwork are related to foundation
excavations, temporary slope construction and foundation subgrade preparation. The soil
conditions anticipated to be encountered within the proposed building envelopes should largely
consist of existing fill (to depths of roughly 12 feet) and native sand soil deposits. The existing
fill contained little to no deleterious debris except minor organics and a relativeiy low fines
content. Soil relative density is generally expe~ed to increase with depth. Although
groundwater seepage is not expected to be a major consideration during earthwork, the
contractor should be prepared to address possible groundwater seepage issues during the,
excavation phase, particularly within the planned excavation for the underground parking level.
Earth Solutions NW. LLC
Conner Homes
December 4, 2012
Temporary Erosion Control
ES-2590
Page 5
In general, control of off-site erosion for this project will likely be limited to construction
entrances. Silt fencing should be installed as needed along the site perimeter. Construction
entrances should consist of quarry spalls underlain by a woven geotextile fabric such as Mirafi
500X. Quarry spall thickness will depend on subgrade stability at the entrance, but should
typically be at least 12 inches.
Expected Sequence of Earthwork
A schedule of earthwork activity and sequencing has not been produced at this time. However,
based on our current understanding of the project, the following should be considered for
sequencing the earthwork:
o Install erosion control measures and initiate parking garage excavation and temporary
slope construction (geotechnical engineer to confirm stability).
o Rough grade remainder of site to establish subgrade for at-grade and step foundations
(building structures). Overexcavate and establish minimum 24 inches of structural fill
below foundations (see following Foundation Subgrade Preparation section of this
study).
o Install perimeter drainage, backfill footing and foundation wall areas, and complete final
grading of the building envelope. Compaction testing of structural backfill soils, as
needed.
o Final landscaping and removal of temporary erosion control (at project completion).
Foundation Subgrade Preparation
Final site layout plans were not developed at the time of this report; however, given the current
topography across the site, grading is anticipated to be minimal. Given the presence of fill
across much of the site, new foundation areas should be overexcavated at least 24 inches and
compacted to a firm and unyielding condition and grades restored using suitable site soils
compacted to structural fill specifications provided in this report.
The following guidelines for preparing the building subgrade should be incorporated into the
final design:
Earth Solutions t#-1. LLC
Conner Homes
December 4, 2012
ES-2590
Pages
o. In general, where voids and related demolition disturbances extend below the planned
building subgrade level, restoration of these areas should be completed as necessary.
Structural fill should be used to restore voids or unstable areas resulting from existing
building removal and site demolition activities.
o Following completion of rough grading, overexcavate stepped and at-grade foundations
areas (building structures) a minimum of 24 inches. The overexcavation shall extend
horizontally a minimum of one foot beyond the perimeter of the new foundation
elements. The subgrade shall be compacted to a firm and unyielding condition prior to
restoring grades with structural fill. Temporary slope excavations to accommodate the
recommended overexcavation shall be no steeper than 1 H: 1 V.
o ENSW shall observe the overexcavated surfaces. Supplement recommendations,
including additional overexcavation, may be provided based on observed conditions.
o Compact structural fill throughout foundation areas to at least 90 percent relative
compaction, based on the maximum dry density as determined by the Modified Proctor
Method.
o ESNW should confirm overall suitability of the prepared subgrade foundation and slab
subgrade areas following the site work activities.
Structural Fill
The native and suitable existing fill soils can be considered for use as structural fill, provided the
soil is at or near the optimum level at the time of placement. Silt soils are generally not
recommended for use as structural fill or wall backfill. The native and existing fill deposits
would be considered to have a moderate to high sensitivity to moisture. These deposits,
particularly the existing silty sand fill will become unstable if exposed to excessive moisture. If
the onsite soils cannot be successfully compacted, the use of an imported soil may be
necessary. Imported soil intended for use as structural fill should consist of a well graded
granular soil with a moisture content that is at or near the optimum level. 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 five percent or less defined as the percent passing the #200
sieve, based on the minus three-quarter inch fraction.
Fills placed in foundation and slab-on-grade areas, as well as wall backfill, utility trench backfill,
and throughout roadway areas are considered structural fill. In general, soils placed in
structural areas should be placed in maximum 12-inch lifts and compacted to a relative
compaction of 90 percent, based on the maximum dry density as determined by the Modified
Proctor Method (ASTM D-1557-02). Roadway subgrade, and areas within the right-of-way will
require 95 percent relative compaction. Utility trench backfill should be compacted to the
specifications of the controlling jurisdiction.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
Foundations
ES-2590
Page 7
The foundation subgrade should be prepared as previously described in the Foundation
Subgrade Preparation section of this study. Stepped and at-grade foundations for the building
structures to be constructed at this site should be supported on a minimum of 24 inches of
structural fill. Provided the foundations are supported as described above, the following
parameters can be used for design:
o Allowable soil bearing capacity
o Coefficient of friction
o Passive resistance
2,500 psf
0.40
350 pcf (equivalent fluid)*
* Assumes foundations backfilled with structural fill
For short term wind and seismic loading, a one-third increase in the allowable soil bearing
capacity can be assumed. A factor-of-safety of 1.5 has been applied to the friction and passive
resistance values.
With structural loading as expected, total settlement in the range of 1.0 inch is anticipated, with
differential settlement of about 0.5 inch. ESNW should review the foundation plan and provide
supplement recommendations for foundation support. ESNW should also observe the prepared
foundation soils during construction to confirm soil conditions and the allowable soil bearing
capacity.
Retaining Walls
Retaining walls should be designed to resist earth pressures and applicable surcharge loads.
The following values should be used for design:
o Active earth pressure (yielding condition 35 pcf (equivalent fluid I granular fill)
o At-rest earth pressure (restrained condition) 50 pcf
o Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution)
o Passive earth pressure 350 pcf (equivalent fluid)
o Allowable soil bearing capacity 2,500 psf
o Coefficient of friction 0.40
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
ES-2590
Page8
Additional surcharge loading from foundations, sloped backfill, or other loading should be
included in the retaining wall design. 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. ESNW should review retaining wall designs to confirm
that appropriate earth pressure values have been incorporated into the design and to provide
additional recommendations.
Retaining walls should be backfilled with free draining material that extends along the height of
the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall
backfill can consist of a less permeable soil, if desired. In lieu of free draining backfill, use of an
approved sheet drain material can 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, as appropriate. A perforated drain pipe should be
placed along the base of the wall, and connected to an appropriate discharge location. A
retaining wall drainage detail is provided on Plate 3.
Slab-On-Grade Floors
Slab-on-grade floors should be supported on a firm and unyielding subgrade consisting of at
least one foot of granular structural fill. Unstable or yielding areas of the subgrade should be
recompacted or overexcavated and replaced with suitable structural fill prior to construction of
the slab. A capillary break consisting of a minimum of four inches of free draining crushed rock
or gravel should be placed below the slab. The free draining material should have a fines
content of five percent or less (percent passing the #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. If a vapor barrier is used, it should consist of a
material specifically designed for that use and installed in accordance with the manufacturer's
specifications.
Drainage
Although groundwater seepage is not expected to be a significant consideration for this project,
minor perched groundwater should be anticipated in site excavations. Temporary measures to
control surface water runoff and groundwater during construction would likely involve
interceptor trenches and sumps. ESNW should be consulted during preliminary grading to
identify areas of seepage and to provide recommendations to reduce the potential for instability
related to seepage effects.
In our opinion, foundation drains should be installed along building perimeter footings. A
footing drain detail is provided on Plate 4.
Earth Solutions NW. LLC
Conner Homes
December 4, 2012
Excavations and Slopes
ES-2590
Page9
The Federal and state Occupation Safety and Health Administration (OSHA/WISHA) classifies
soils in terms of minimum safe slope inclinations. In our opinion, based on the soil conditions
encountered during fieldwork for this site, the existing fill, loose native soil and where
groundwater is exposed would be classified by OSHA/WISHA as Type C. Temporary slopes
over four feet in height in Type C soils should be sloped at an inclination of 1.5H:1V, or flatter.
Below the existing fill deposits, the medium dense native soil deposits would be characterized
as Type B. Temporary slopes in Type B soils should be sloped at an inclination of 1H:1V, or
flatter. ESNW should observe the excavations to confirm the appropriate allowable temporary
slope inclination. Additionally, guidelines for temporary slope construction related to the
planned underground garage level excavation are provided in the previous Site Preparation and
Earthwork section of this study. If temporary slope construction cannot be accomplished, the
use of temporary shoring may be required.
Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with an
appropriate species of vegetation to enhance stability and to minimize erosion.
Seismic Considerations
The 2009 International Building Code specifies several soil profiles that are used as a basis for
seismic design of structures. Based on the soil conditions observed at the test sites, Site Class
D, from table 1613.5.2, should be used for design. In our opinion, the site has a low
susceptibility to liquefaction. The absence of an established shallow groundwater table, and
the soil relative density observed throughout the test sites is the primary basis for this
conclusion.
Utility. Support and Trench Backfill
In our opinion, the soils observed at the boring locations are generally suitable for support of
utilities. Organic or highly compressible soils encountered in the trench excavations should not
be used for supporting utilities. The onsite soils observed at the test sites may be suitable for
use as structural backfill in the utility trench excavations, pending confirmation by the
geotechnical engineer. Moisture conditioning of the soils may be necessary prior to use as
structural fill. Where the onsite soils are determined to be unsuitable for use as structural fill,
use of a suitable imported granular soil may be necessary. The presence of groundwater could
be encountered in site excavations, such as the deeper utility trench excavations. Utility trench
backfill should be placed and compacted to the specifications of structural fill provided in this
report, or to the applicable specifications of the city or utility district jurisdictions.
Earth Solutlons NW, LLC
Conner Homes
December 4, 2012
LIMITATIONS
ES-2590
Page 10
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. A warranty is not
expressed or implied. Variations in the soil and groundwater conditions identified at the test
sites may exist, and may not become evident until construction. ESNW should reevaluate the
conclusions 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. ESNW should also be retained to provide testing and
consultation services during construction.
\
Earth Solutions NW, LLC
Reference :
King County, Washington
Map 626
By The Thomas Guide
Rand McNally
32nd Edition
Mfflf.
.J
Vicinity Map
Park Place Short Plat
Renton , Washington
NOTE: This plate may contain areas of color. ESNW cannot be Drwn . GLS Date 11/19/2012 Proj . No . 2590
responsible for any subsequent misinterpretation of the information
resulting from black & white reproductions of this plate. Checked SSR Date Nov. 2012 Plate 1
------------I
I
I
I
-,_ ----------------------------
N. 26TH STREET
200 210
\ I 220
\ I 1 \ /
I ,.. ,----';;--7 "? -::::-----+-----,..C----~ -----~-----'.... , < , ' 'r/ // /,,,. -,•I TP-4 \ \ : ; /·--,----,~---~--rr1-::
I ' I I I I I / .,... ,... -.., \ \ I I \ I I I , ,,,.230
I I I I I I I / i.... I I ' I I { I I I 1/,
/..J..; /11111',! / I I/ I / I I ')'
I (.j /' / I I I I I }' J I \ I I ,,.. ,.... \ \ 1 I , / ~ I J I / / / / jl / / \ \ / ,,.. I I I I / /
I "-/ I J I I I I I I \ l / I ) \ I ,1. 1
I ct! • I / 11 / 7•1-/ I /\ I I I I I
190--11,111:, ,' r TP;1 Appft>ximate : : : : ,/ \ ; ,; ,
~ \ ' I / : : : I ( r ( ~ Top of Regulated I I I l ( / \ I ,'/ ,' ~ '/ i I I I I 1 I \ \'..er--/ ,' Slope ~ 1 I : \ ; / 1/ '
I
I
~ , 1 I I I i ) I \ \ I; I _1 I : : I \ / / ,'i ,'
' / 1 1 / / 1 , / /, ~· \<J--;;.L.-Approximate \ 1 t 1 1 ,'' ,; ,
/ ; ! 1 1 ' 1 , , / )' , ,, ,, 15' Buffer I I ..L1 1 : 1 , / '/' ,'
I
I
I
I I I I I r / / y_ ---,_• I \ / / /
I' \ / I I I I I I : f / <' TP-311 f I I \ / / /; ' \,1111,1..._,-...'" // ', 11,1: ', ,,,;,'
'I 1111, ,,,~, ' 1 I ' 1,1. / 11 11 ,, ', ,,-..:v,1~ , I It , / '/ I //r<,,;-::,,,,,'~,,,,'.,ITP-2" (111 , ,/1, \
I I [ '', '',' ' '', ~-·-\ \ I j I \ , , ,.,
L.l._ \ I , ',, ',, ',, '""' \ I ! ! \ / / j I
I --,---.._ -'---~----;-....:..-~-B>~--.!.--------..! ..t.-~---------.... -c..::::..~-.L~..!J /
I ' 'Qa..... _ _..
I ' , , I
I 200 ', ' ',
190 1 '· 220 210 230
LEGEND
TP-1-0
1
1 -Approximate Location of
ESNW Test Pit, Proj. No.
ES-2590, Nov. 2012
----·-1 ! 1 Subject Site
L---.. -'
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 I 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.
0
1 "=40"
40 80
LJ Scale in Feet
Test Pit Location Plan
ParkPlace Short Plat
Renton, Washington
NOTE: This plate may contain areas of color. ESNW cannot be
responsible for any subsequent misir1terpretation of the information
resulting from black & white reproductions of this plate.
Drwn. GLS Date11/20/2012 Proj. No. 2590
Checked SSR Date Nov. 2012 Plate 2
18" Min . .... r-----~1
NOTES:
o Free Draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing #4 should be 25 to
75 percent.
o Sheet Drain may be feasible in lieu
of Free Draining Backfill, per ESNW
recommendations.
o Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1"
Drain Rock.
LEGEND:
Free Draining Structural Backfill
1 inch Drain Rock
Structural
Fill
SCHEMATIC ONLY-NOTTO SCALE
NOT A CONSTRUCTION DRAWING
RETAINING WALL DRAINAGE DETAIL
Park Place Short Plat
Renton, Washington
Drwn. GLS Date12/04/2012 Proj. No. 2590
Checked SSR Date Dec. 2012 Plate 3
Slope
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...
2" (Min.)
Perforated Rigid Drain Pipe
(Surround with 1" Rock)
NOTES:
e Do NOT tie roof downspouts
to Footing Drain.
e 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.
1" Drain Rock
SCHEMATIC ONLY -NOTTO SCALE
NOT A CONSTRUCTION DRAWING
Drwn. GLS
FOOTING DRAIN DETAIL
Park Place Short Plat
Renton, Washington
Date12/04/2012 Proj. No. 2590
Checked SSR Date Dec. 2012 Plate 4
APPENDIX A
SUBSURFACE EXPLORATION
ES-2590
The subsurface conditions at the site were explored by excavating four test pits to maximum
depths of 12.5 feet below existing grades. The approximate locations of the test pits are
illustrated on Plate 2 of this report. The test pit logs are provided in this Appendix of the report.
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
Earth Solutions NWLLc
SOIL CLASSIFICATION CHART
MAJOR DMSIONS SYMBOLS
. GRAPH LETTER
TYPICAL
DESCRI.PTIONS
COARSE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL JS
LARGER THAN
NO. 200 SIEVE
SIZE
FINE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL IS
SMALLER THAN
NO. 200 SIEVE
SIZE
GRAVEL
AND
GRAVELLY
SOILS
MORE THAN 50%
OF COARSE
FRACTION
RETAINED ON NO.
4SIEVE
SAND
AND
SANDY
SOILS
CLEAN
GRAVELS
(LITTLE OR NO FINES)
GRAVELS WITH
FINES
(APPRECIABLE
AMOUNT OF FINES)
CLEAN SANDS
(LITTLE OR NO FINES)
SANDS WITH
MORE THAN 50% FINES
OF COARSE
FRACTION
PASSrNG ON NO.
4 SIEVE (APPRECIABLE
SILTS
AND
CLAYS
SILTS
AND
CLAYS
AMOUNT OF FINES)
LIQUID LIMIT
LESS THAN SO
LIQUID LIMIT
GREATER THAN 50
HIGHLY ORGANIC SOILS
GW
GP
GIiii
GC
SW
SP
SM
SC
iVlL
CL
OL
MH
CH
OH
PT
WELL-GRADED GRAVELS, GRAVEL·
SANO MIXTURES, LITTLE OR NO
FINES
POORLY-GRADED GRAVELS,
GAAVEL -SAND MIXTURES, umE
ORNOFINES
SILTY GRAVELS, GRAVEL ·SAND -
SILT MIXTURES
CLAYEYGRAVEl.S, GRAVEL• SAND-
CLAY MIXlURES
WELL-GRADED SANDS, GRAVELLY
SANOS, LrTTl.E. OR NO FINES
POORL Y-GRAOED SANDS,
GRAVELLY SAND, LITTLE OR NO
FINES
SIL TY SANDS, SAND· SILT
MIXTURES
CLAYEY SANDS, SAND-CLAY
MIXlURES
INORGANIC SILTS AND VERY ANE
SANDS, ROCK FLOUR, SILTY OR
ClAYEY FINE SANDS OR ClAYEY
SILTS wmt SLIGHT PlASTICITY
INORGANIC ClAYS OF LOW TO
MEOIIJM PLASTICITY, GRAVELLY
ClAYS, SANOY CIAYS, SILTY
ClAYS, LEAN CLAYS
ORGANIC SIL TS AND ORGANIC
SILTY CLAYS OF LOW PLASTICrTY
INORGANIC SILTS, MJCACEOUS OR
OIATOMACEOUS FINE SAND OR
SlllYSOILS
INORGANIC ClAYS OF HIGH
PLASTICITY
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
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 Iha material presented in the attached logs.
• Earth Solutions NW TEST PIT NUMBER TP-1
1805136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Ren1on, Washlng!on
DATE STARTED 11/5/12 COMPL~D 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION -
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES D!!!!lh ofToesoil & Sod 6": X@rd Qr.!!SS AFTER EXCAVATION -
w
:,: ~ffi ui u a;g !!I"' TESTS ti ii: 8 MA TE RIAL DESCRIPTION a.::. ui ~.J 0 i~ :j (!)
n
Brown silty SAND, loose, moist (Fill)
. . -scattered gravel
MC= 16.10%
' . . -becomes medium dense
>-2---variable silt content
.. . SM -becomes with gravel
.. . MC= 10.20%
Fines = 15.20%
. -asphalt pieces
.. '
..J.Q_ ~
-.
~ 12.D . . (:l: Brown silty SANO, medium dense, moist
MC= 14.90%
SM 12.6
Test pit terminated at 12.5 feet below existing grade. No groundwater encountered during
' excavation.
Bottom of test ptt et 12.5 feet.
• Earth Solutions NW TEST PIT NUMBER TP-2
1805 136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT ConM:r Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton, Washinaton
DATE STARTED 11/5/12 COMPLETED 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS: .
EXCAVATION MErnOD AT TIME OF EXCAVATION
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES Deg!!! ofTogaoil & Sod 6": ~rd _greas AFTER EXCAVATION -·
w
Q. Q
~=-~ ffi <Ji
w"' TESTS ti il: 8 MATERIAL DESCRIPTION w-...J::!; <Ji ~...J C 1~ :;j (.?
0
Brown silty SANO, loose, moist (Fill)
. . -scattered gravel
-.. m -fine roots
-asphalt pieces -
MC= 13.70% -becomes medium dense
" .
"""' ,_L
SM
" . ~ -phslt pieces
" .
' ~ MC= 11.70%
a .
.J.Q....
10.5
MC=11.70%
SM-:· :, . 11.0 Gray brown silty SAND, medium dense, moist . Test pit terminated at 11.0 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test pit at 11.0 feet.
i
• Earth Solutions NW TEST PIT NUMBER TP-3
1805138th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner tlOmes PROJECT NAME Park Piece Shod Plat
PROJECT NUMBER 2590 PROJECT.LOCATION Renton, WBshltigton
DATE STARTED 11/5112 COMPLETED 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION -
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES De(!!h of TQPSOII & S2d 6": lBrd 11rass AFTER EXCAVATION -
w
~g
~ ffi .; u
:CC) w co TESTS 0 ll. 0 MATERIAL DESCRIPTION ..J::;; <ri il! ..J 0 11.:::, :; iz Cl
n
Derk brown silty SAND, loose, we1 {Fill)
" SM
2.0 --. I Brown silty fine SAND, loose, moist
--
--
..
_L SM ' .
--. -,,
MC= 10.90%
I:,' 8,0 --Test pit tennineted at-_8.0 feet below axtsting grade. No groundwater encountered during
excavation;
Bottom of test pit at 8.0 feet
'
• Earth Solutions NW TEST PIT NUMBER TP-4
1805136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton 1 Washlng!on
DATE STARTED 11/5/12 COMPLETED 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION -
LOGGED BY SSR CHECKED BY. SSR AT END OF EXCAVATION
NOTES De~th of Tol!!oll & Sod 6": yanfgrass AFTER EXCAVATION -
w
0.
~€
~ ffi vi u
:i: (!) w"' TESTS u o.o MATERIAL DESCRIPTION -':; vi cl!-' 0 0.::, :;j
~z (!)
0
~I Brown silty SAND, loose, moist (Fill}
-
. -
MC= 13.60% . -Fines= 28.30%
4.0 -asphalt pieces
Brown fine SAND with silt, medium dense, moist
~I
SP-·1···
SM '
MC= 11.60% ' 6.0 .. . Fines = 9.50% Test pit terminated at 6.0 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test prt at 6.0 feet.
APPENDIX B
LABORATORY TEST RESULTS
ES-2590
Earth Solutions NW, LLC
•
Earth Solutions NW GRAIN SIZE DISTRIBUTION
.
1805-1361h Place N.E., Suite 201
BeDevue, WA 98005
Telephone: 425-284-3300
CLIENT Conner Homea
PROJECT NUMBER ES-2590
U.S. SIEVE OPENING IN INCHES I
6 4 3 2 :.."I 1 .~' i/2318 3
100 I 1 1\ ,;'. \ I I
95
\ \
90 : !
85
BO
75
:
70 I
65 !i:
(!) 60 i
f
' I'
; I
:
>-55 a,
a: w 50 z
ii:
I-z 45
w
0 40 a:
~
35
30
25 ';
20
15
I:
10 i
5
0
100 10
GRAVEL
. ' I
PROJECT NAME Park Place Short Plat
PROJECT LOCATION Renton
U.S. SIEVE NUMBERS I
,·e,0:14 1.16 20 So 4o 50 so 100140200
I II : I I I
I
""'-\
' ..
,\
; \ ;
' :
·I\. ;
: \ .
I \ :
' ! I
:, ~
""
:
I
\
1 0.1
GRAIN SIZE IN MILLIMETERS
HYDROMETER
0.01
SAND SILT OR CLAY COBBLES coarse flne coarse medium fine
0.001
Specimen Identification Classification LL PL Pl Cc Cu
~ o TP-1 i .Clft. Brown silty SAND with gravel, SM
3.0ft. Brown sllty SAND with gravel, SM
6.0ft. Brown poorly graded SAND with sllt, SP.SM I 1.45 4.24
!I!
!.1-L-----"---l------.----.---~--.---..------,-L-.....-L..,-L-L,-....L.,--I a D10
...
Specimen Identification D100 D60 D30 %Gravel %Sand %Silt %Clay
0 TP-1 7.0ft. 37.5 1.121 0.241
® TP-4 3.0ft. 19 1.307 0.094
6 TP-4 6.0ft. 37.5 ' 0.343 0.201
22.9 61.9 15.2
28.0 43.8 28.3
8.7 i 81.7 9.5
11-1-----....:....:-1-_.::_;..c....-+--=-+----l-----i~----1-o---1-o-------l
0.081 ~1-1-----...C.-'---l--'-'.C..:....-.J--.C....:..:C......j---~-+-----!-----+~=---l----~----1
!1-L.. ____ ......__ _ __.L __ ....__ _ __._ __ .L..-_......L... _ ___. ____ __.
E-MAIL COPY
REPORT DISTRIBUTION
ES-2690
Conner Homes
846-' 1081h Avenue Northeast
Bellevue,. Washington 98004
Attention: ML Rob Risinger
Earth Solutions NW,. LLC
APPENDIX B
TESC BMP Details
I I
I I
LJ
JOINTS IN FILTER FABRIC SHALL BE SPLICED
AT POSTS. USE STAPLES, WIRE RINGS, OR
EQUIVALENT TO ATIACH FABRIC TO POSTS.
POST SPACING MAY BE INCREASED
TO B' IF WIRE BACKING IS USED
NOTES
1. CONDITION OF USE
1.1. SILT FENCE MAY BE USED DOWNSLOPE OF All DISTURBED AREAS.
2·~2· BY 14 Ga. WIRE OR
EQUIVALENT, IF STANDARD
STRENGTH FABRIC USED
FILTER FABRIC ---o,-
MINIMUM4",4"TRENCH ~ /
BACKFILL TRENCH WITH
NATIVE SOI/
2"K4" WOOD POSTS STEEL FENCE
POSTS, REBAR, OR EQUIVALENT
z >
N
1.2. SILT FENCE IS NOT INTENDED TO TREAT CONCENTRATED FLOWS, NOR 1S INTENDED TO TREAT SUBSTANTIAL AMOUNTS OF OVERLAND FLOW.
ANY CONCENTRATED FLOW MOST BE CONVEYED THROUGH THE DRAINAGE SYSTEM TO A SEDIMENT TRAP OR POND.
2. DESIGN ANO INSTALLATION SPECIFICATIONS
2.1. THE GEOTEXTlLE USED MOST MET THE STANDARD LISTED BELLOW. A COPY OF THE MANUFACTURER'S FABRIC SPECIFICATIONS MOST BE
AVAILABLE ON SITE
AOS (ASTM 04751)
3().100SIEVE SIZE (0.6Q.0. 15MM) FOR SILT FILM
50.lOOSIEVE SIZE (0.30·0.lSMMl FOR OTHER FABRICS
WATER PERMITIIVITY (ASTM049ll 0.02 5[(11...l MINIMUM
GRAB TfNSILE STRENCHT (ASTM D4632) 180 LBS. MIN, FOR EXTRA STRENGH FABRIC
100 LBS. MIN. FOR STANDARD STRENGHl fABRIC
GRAB TENSILE ELONGATION IASTM D4632 30%MAX.
ULTAAVIOLATE RESISTANCE IASTM 04355 70%MIN.
2.2. STANDARD STRENGTH FABRIC REQUIRES WIRE BACKING TO INCREASE THE STRENGTH OF THE FENCE. WIRE BACKING OR CLOSER POST
SPACING MAY BE REQUIRED FOR EXTRA STRENGTH FABRIC IF FIELD PERFORMANCE WARRANTS A STRONGER FENCE.
2.3. WHERE THE FENCE IS INSTALLED, THE SLOPE SHALL NOT BE STEEPER THAN 2H:1V
2.4. IF A TYPICAL SILT FENCE IS USED, THE STANDARD 4X4 TRENCH MAY NOT BE REDUCED AS LONG AS THE BOTIOM 8 INCHES OF THE SILT FENCE
IS WELL BURIED ANO SECURE IN A TRENCH THAT STABILIZES THE FENCE AND DOES NOT ALLOW WATER TO BYPASS OR UNDERMINE THE SILT
FENCE.
3. MAINTENANCE STANDARDS
3.1. ANY DAMAGE SHALL BE REPAIR IMMEDIATELY.
3.2. IF CONCENTRATED FLOES ARE EVIDENT UPHILL OD THE FENCE, THEY MUST BE INTERCEPTED AND CONVEYED TO A SEDIMENT TRAP OR PONO.
3.3. IT IS IMPORTANT TO CHECK THE UPHILL SIDE OF THE FENCE FOR SIGNS OF THE FENCE CLOGGING AND ACTING AS A BARRIER TO FLOW AND
THEN CAUSING CHANNELIZATION OF FLOWS PARALLEL TO THE FENCE. IF THIS OCCURS, REPLACE THE FENCE OR REMOVED THE TRAP
SEDIMENT.
3.4. SEDIMENT MOST BE REMOVED WHEN SEDIMENT IS 6 INCHES HIGH.
3.5. IF THE FILTER FABRIC (GEOTEXTILE) HAS DETERIORATED DUE TO ULTRAVIOLET BREAKDOWN, IT SHALL BE REPLACED.
PUBLIC WORKS
DEPARTMENT
son.. ,r IFIEINICIE
STD. PLAN -214.00
MARCH 2008
DRAINAGE GRATE
GRATE FRAME
SEDIMENT AND DEBRIS
OVERFLOW BYPASS
.. · .. • BELOW INLET GRATE DEVICE
. " ·,
.• ' t,.' . LJ.
!,-----~-'
• • ... . ..
DRAINAGE GRATE
~ RECTANGUIAR GRATE SHOWN
BELOW INLETGRA.TE DEVICE
SECTION VIEW
180rJJETRIC VIEW
NOTES
OVERFLOW BYPASS (TYP.)
1. Size the Balow Inlet Grate Device (BIGD) fa' the storm water structure It will service.
2. The BIGD shall have a built-In high-flow reUaf syatem (Olel'ftow bypass).
3. The retrieval ayatem must allow removal of the BIGO without spllllng the collected material.
4. Perform maintenance In accordance with Standard SpedflCBtlon 8-01.3(15).
PUBLIC WORKS
DEPARTMENT
C£.'V'CIXI IBIASOti\11 IFOII.. 'V'IEIR! STD. PLAN -216.30
MARCH 2008
APPENDIX C
Roof Infiltration Detail
.. • • ""! ,g -v ? .. ~~
j~
~~
i
i
I ~~ J;
PROJECT
PROJECT
DATE:
NAME: 26TH SHORT PLAT
NO: 258-040-012
REF. DRAWING:
2013-02-04
EX-01.dwg
N t: -"
_l 24'
N t: -"
VARIES
30 LF PER 1000 SF OF ROOF' AREA
INFILTRATION TRENCH
ILTER FABRIC
AROUND TRENCH
l-----4 •11 RIGID PERFORATED PIPE
66 MIN SPACING BETWEEN TOP
OF PIPE ANO FILTER FABRIC
WASHED ROCK
1.s·, 10 o.1s•11
4•1 RIGID PERFORATED PIPE
OR 5•1 FLEXIBLE PERFORATED PIPE
PAOFLE I/IEW
10' MIN
HOUSE
4•i, SOLID PIPE
ROOF DRAIN
~-
w-~iii~~~~~~:;;:;.~~~f:11~:--:--:-:~~=--:-~~-:--::--::-:-~=--:::-:-:-~-:--::--:---:::--:-~~=-:~=-~~=-=--=-~-, ~~ UR-i&:i CQNSULJING ENGINEERS LLD
IC O --= .. --3:)4005thAva5, """~205 I • 1-t> 101 ;s. ,.,.,.www.-,oo, =-lll:l::o::: SINGLE FAMILY ROOF DOWNSPOUT INFILTRATION TRENCH ! ~ www.HmciYll.com
::::t ~.:--:..--;:~, I ~.:-:.:..,. ::--..:::-::-.. NOT TO SCALE
iu 0 [ ii: DRAWING: EX-01 SHra 1 OF 1 D~WN, ~p
Geotechnical Engi neering
Geology
Environmental Scient ists
Construction Monitoring
City of Renton
Planning Division
FEB -6 W13
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLAT
1311 NORTH 26TH STREET
RENTON, WASHINGTON
ES-2590
PREPARED FOR
CONNER HOMES
December 4, 2012
Kyle R. Campbell, P.E.
Principal
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLAT
1311 NORTH 26TH STREET
RENTON, WASHINGTON
ES-2590
Earth Solutions NW, LLC
1805-136th Place Northeast, Suite 201, Bellevue, Washington 98005
Ph: 425-449-4704 Fax: 425-449-4711
Toll Free: 866-336-8710
·. rmportant Information About Your
Geotechnical Engineering Report
-· Subsurface /Jro/Jlems a1c a p1111c11;al cause of const111ctwn delays, cost ov,,1ru11:o, c!wn,. anr! rltsputes . • The !ollmv111y 111!01111alw111s p1u,•1rler! IO help you manaye yolll 1/sAs
Geotecllnlcal Services llre Performed for
Speclllc Purposes, Persons, and Projects
Geotechnical engineers structure their services to meet the specific needs of
their clients. A geotechnical engineering study conducted for a civil engi·
neer may not fulfill the needs of a construction contractor or even another
civil engineer. Because each geotechnical engineering study is unique, each
geotechnical engineering report is unique, prepared solely for the client. No
one except you should rely on your geotechnical engineering report without
first conferring with the geotechnical engineer who prepared it And no one
-not even you -should apply the report for any purpose or project
except the one originally contemplated.
Realll lhe Full Report
Serious problems have oCCtJrred because those relying on a geotechnical
engineering report did not read it all. Do not rely on an executive summary.
Do not read selected elements only.
ll Geotechnical Engineering Report Is Based on
ll URlque Set ol ProJect-Specilic Factors
Geotechnical engineers consider a number of unique, project-specific fac-
tors when establishing the scope of a study. Typical factors include: the
client's goals, objectives, and risk management preferences; the general
nature of the structure involved, ils size, and configuration; the location of
the structure on the site; and other planned or existing site improvements,
such as access roads, parking lots, and underground utilities. Unless the
geotechnical engineer who conducted the study specifically indicates oth-
erwise, do not rely on a geotechnical engineering report that was:
o not prepared for you,
o not prepared for your project,
o not prepared for the specific site explored, or
o completed before important project changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those that affect:
0 the function of the proposed structure. as when it's changed from a
parking garage to an office building, or from a light industrial plant
to a refrigerated warehouse,
• elevation, configuration. location, orientation, or weight of the
proposed structure.
• composition of the design team, or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
changes-even minor onBS-illld request an assessment of their impact.
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider developments of which
they 11-11re not informed.
Subsurface O:Omlltl• can Change
A geotechnical engineering report is based on conditions that existed at
the time the study was pertormed. Do not rely on a geotechnical engineer-
ing repollwhose adequacy may have been affected by: the passage of
time; by man-made events. such as construction on or adjacent to the site;
or by natural events, such as floods, earthquakes, or groundwater fluctua-
tions. Alw.1yscontact the geotechnical engineer before applying the report
to determine if it is still reliable. A minor amount of additional testing or
analysis could prevent major problems.
Most Geotecllnical Findings llre Professional
Opinions
Site exploration identifies subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnical engi-
neers review 1ield and laboratory data and then apply their professional
judgment to render an opinion about subsurtace conditions throughout the
site. Actual subsurface conditions may differ-sometimes significantly--
from those indicated in your report. Retaining the geotechnical engineer
who developed your report to provide construction observation is the
most effective method of managing the risks associated with unanticipated
conditions.
ll Report's Recommendations Are 11/ot Final
Do not overrely on the construction recommendations included in your
report. Those recommendations are not final. because geotechnical engi-
neers develop them principally from judgment and opinion. Geotechnical
engineers can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnica/
engineer who developed your report cannot as_sume responsibilily or
liability tor the report's recommendations if that engineer does not perform
construction observation.
Ii Geotechnical EngineerinU Report Is Subject to
Misinterpretation
Other design team members' misintB1Pretation of geotechnical engineering
reports has resulted in costly problems. Lower that risk by having your geo-
technical engineer confer with appropriate members of the design team after
submitting the report. Also retain your geotechnical engineer to review perti-
nent elements of the design team's pians and specifications. Contractors can
also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconslruction
conferences, and by providing construction observation.
Do Not Redraw the Engineer's Logs
Geotechnical engineers prepare final boring and testing logs based upon
their interpretation of field logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating togs from the report can elevate risk.
Give Contractors a Complete Report and
Guidance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly problems, give con-
tractors the complete geotechnical engineering report, bu/preface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the
report's accuracy is limited; encourage them to confer with the geotechnical
engineer who prepared the report (a modest fee may be required) and/or to
conduct additional study to obtain the specific types of information they
need or prefer. A prebid conference can also be valuable. Be sure contrac-
tors have sufficient time to perform additional study. Only then might you
be in a position to give contractors the best information available to you,
while requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions.
Realll Responsll!IDIY ProVlslons Closely
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineering disci-
plines. This lack of understanding has created unrealistic expectations that
have led to disappointments, claims, and disputes. To help reduce the risk
of such outcomes, geotechnical engineers commonly include a variety of
explanatory provisions in their reports. Sometimes labeled 'limitations"
many of these provisions indicate where geotechnical engineers' responsi-
bilities 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.
Geoenvlronmental Concerns Are Not Covered
The equipment, techniques, and personnel used to pertorm a geoenviron-
mental study differ significantly from those used to pertorrn a geotechnical
study. For that reason, a geotechnical engineering report does not usually
relate any geoenvironmental findings, conclusions, or recommendations;
e.g., about the likelihood of encountering underground storage tanks or
regulated contaminants. Unanticipated environmenliil problems have led
to numerous project failures. If you have not yet obtained your own geoen-
vironmental information, ask your geotechnical consultant for risk man-
agement guidance. Do not rely on an environmental report prepared for
someone else.
Obtain Proresslonal Assistance To Deal with Mold
Diverse strategies can be applied during building design, construction,
operation, and maintenance to prevent significant amounts of mold from
growing on indoor surfaces. To be effective, all such strategies should be
devised for the express purpose of mold prevention, integrated into a com-
prehensive plan, and executed with diligent oversight by a professional
mold prevention consultant. Because just a small amount of water or
moisture can lead to the development of severe mold infestations, a num-
ber of mold prevention strategies focus on keeping building surtaces dry.
While groundwater, water infiltration, and similar issues may have been
addressed as part of the geotechnical engineering study whose findings
are conveyed in-this report, the geotechnical engineer in charge of this
project is not a mold prevention consultant; none of the services per-
formed In connection with the geotechnlcal engineer's s/udy
were designed or conducted for /he purpose ol mold prsvsn-
1/on. Proper lmplsmslllalion of ths recommsndatlons conveyed
In this report will not of ltsslf be sufficient to prevent mold from
growing In or on the structure Involved.
~ely, on Your ASFH'iember Geotechnclal
Engllleer lor AddWonal Assistance
Membership in ASFE/The Best People on Earth exposes geotechnical
engineers to a wide array of risk management techniques that can be of
genuine benefit for everyone involved with a construction project. Confer
with you A;,FE-member geotechnical engineer for more information.
ASFE
Ibo DIii PoiDII Ii IUIII
8811 Colesville Road/Suite 6106, Silver Spring, MD 20910
Telephone: 301/565-2733 Facsimile: 301/589-2017 •
e-mail: into@aste.org www.asfe.org
Copyright 2004 by ASFE, Inc. Oup/lcatlon, reproduction, or copying of this document, In whole or In pan, by any medns wha+,r. Is strictly prohibited, except with ASFE's
specific written perm;sslon. Excsrpting, quoting, or otherwisB extracting wording from this document Is permitted only with ths"e.Vpress written pennlsslon of ASFE. and only for
purposes of scholarly research or book rsvlew. Only members of ASFE may use this document as a complement to or as an element of a geotechnlcal engineering report. Any other
ffrm, lndfvfdua/, or oth6r entity that so uses this document without being an ASFE member coufd be cr,mmlttfng negfigent or Intentional (fraudulent) misrepresentation.
IIGER06045.0M
December 4, 2012
ES-2590
Conner Homes
846 -1 oath Avenue Northeast
Bellevue, Washington 98004
Attention: Mr. Rob Risinger
Dear Mr. Risinger:
Earth Solutions NW LLC
• Geolechnical Engineering
• Construction Monitoring
• Environmental Sciences
Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical
Engineering Study, Proposed Residential Short Plat, 1311 North 25th Street, Renton,
Washington". We understand the site will be subdivided into three or four detached residential
lots and associated improvements.
In our opinion, provided the recommendations of this study are incorporated into the final
design, construction of the residential structures is feasible from a geotechnical standpoint.
Based on the expected subsurface conditions, the proposed building structures can be
supported on conventional continuous and spread footing foundations bearing on medium
dense native soils (where encountered), or at least 18 inches of suitable site soil compacted to
structural fill specifications.
Recommendations for site excavations, foundation subgrade preparation, foundation design
and other pertinent geotechnical recommendations are provided in this study.
The opportunity to be of service to you is appreciated. If you have any questions regarding the
content of this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
1805 -136th Place N.E., Suite 201 • Bellevue, WA 96005 • (425) 449-4704 • FAX (425) 449-4711
INTRODUCTION
TABLE OF CONTENTS
ES-2590
PAGE
... ~; .. ~.-........ ·.-. ..................... · .. ; ............................ .. 1
General ........................................................................ · ... , 1
Project Description . . . . . . . •. . . . . . .. . .. . .. .. . . . . . .. . .. . . . .. . .. . . . . . . . . . . .. . . . . . 1
Surface ....................•... , .. , ...... ,, .... ,................................... 2
Subsurface ..................... ,.· .... , .......... ,................................ 2
Groundwater ................................ , .................................... 2
CRITICAL AREAS ASSESSMENT ........................................... .c ••• ,. 3
Erosion Hazards ................................... ,., ................. , ........ 3
Landslide Hazards .......•............. : ..... :................................. 3
Steep Slope Hazards .............................. , ........................... 3
Foundation Setbacks ..................................•...... , .... ,.......... 4
DISCUSSION AND RECOMMENDATIONS ............................... , ....•.. 4
GeneraL •. , ................................................... , .. , ... ,,,. ... , ..•... 4
Site Preparation and Earthwork ............ , ... ,., .... , ................... 4
Temporary Erosion Control ........................................ 5
Expected Sequence of Earthwork ... , .•..• , .•..•... , .......... :. 5
Foundation Subgrade Preparation............................. 5
Structural Fill. ....................................................... :. 6
Foundations .................................................... , ....... ,., ..... :.. 7
Retaining Walls ........•.•.... ,.-............... , .......................... , ... ,. 7
Slab-on-Grade Floors ............................. , ... :,...................... 8
Drainage ................................ , .... , .......•. ,., ... · ...................... 8
Excavations and Slopes ............................... , ................ , .. , 9
Seismic Considerations ................. :....... ............ .....•... ... ....... 9
Utility Support and Trench Backfill.. ........................ , ......... ,. 9
LIMITATIONS .............. :............................................................... 10
Additional Services ...................... , ................•. , .... :·············· 10
Earth Solutions NW, LLC
GRAPHICS
PLATE 1
PLATE2
P~TE~
PLATE4
APPENDICES
Appendix A
Appendix B
TABLE OF CONTENTS
Cont'd
VICINITY MAP
TEST PIT LOCATION PLAN
RETAINING WALL DRAINAGE DETAIL
FOOTING DRAIN DETAIL
Subsurface Exploration
Test Pit Logs
Laboratory Test Results
Eatth.Soltillons NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL SHORT PLA
1311 NORTH 26TH STREET
RENTON, WASHINGTON
ES-2590
INTRODUCTION
General
This geotechnical engineering study was prepared for the proposed residential short plat to be
constructed in the lower Kennydale neighborhood of Renton, Washington. The approximate
location of the site is illustrated on the Vicinity Map (Plate 1 ). The purpose of this study was to
develop geotechnical recommendations for the proposed project. The scope of services for
completing this geotechnical engineering study included the following:
o conduct subsurface explorations to characterize the soil and groundwater conditions;
o Performing engineering analyses, and;
o Preparation of this geotechnical engineering study.
As part of preparing this study, the following documents and resources were reviewed:
o The City of Renton Critical Areas Regulations.
o Geologic Map of the Renton Quadrangle, King County, Washington.
o USDA NRCS Web Soil Survey GIS database.
Project Description
We understand the property will be subdivided into three or four detached residential projects.
The approximate limits of the proposed development are illustrated on the Test Pit Location
Plan (Plate 2). Based on existing topography, grading will likely be limited to establishing
subgrade elevations for the new residential structures.
The proposed building construction will likely consist of relatively lightly-loaded wood frame
construction supported on conventional foundation systems. At the time this report was
prepared, specific building load values were not available. However, based on our experience
with similar developments, we anticipate perimeter wall loads of approximately 1 to 2 kips per
lineal foot and slab on grade loading on the order of 150 pounds per square foot.
Conner Homes
December 4, 2012
ES-2590
Page 2
If the above design estimates are incorrect or change, ESNW should be contacted to review the
recommendations in this report. ESNW should review the final design to verify that our
geotechnical recommendations have been incorporated into the final design.
Surface
The subject site is located in the southeastern corner of the intersection between North 261h
Street and Park Place North in the Lower Kennydale neighborhood of Renton, Washington.
The approximate location of the site is illustrated on the Vicinity Map (Plate 1 ). The property is
bordered to the north by North 26th Street, to the south and east by existing residential parcels
and to the west by Park Place North. The eastern margin of the site is currently occupied by a
residence and landscaped with lawn and areas of sparse vegetation. Topography is relatively
level across the approximate western 213rd of the site where the new lots will be created. A
slope descends from the west and north property boundaries to the rights-of-way and from the
south to the adjacent residential property, creating an elevated pad configuration.
Subsurface
A representative of ESNW observed, logged and sampled four test pits advanced within
accessible areas of the subject site for purposes of characterizing and classifying the site soils.
The test pits were excavated using a backhoe and operator provided by the client. Please refer
to the test pit logs provided in Appendix A for a more detailed description of the subsurface
conditions. The approximate test pit locations are illustrated on the Test Pit Location Plan
(Plate 2).
Underlying the topsoil, loose to medium dense silty sand fill (Unified Soil Classifications SM)
was encountered extending to depths of about two and one-half feet at test pit location TP-3 to
about 10.5 feet at test pit location TP-2 and about 12 feet at test pit location TP-1. Underlying
the fill, medium dense to dense silty sand and sand (SM and SP-SM) was encountered
extending to the maximum exploration depth of 12.5 feet below existing grade. The fill
contained only trace amounts of deleterious debris such as asphalt pieces and was generally
consistent from a textural standpoint.
The referenced Geologic Map identifies glacial till (Qvt) and advance outwash (Qva) across the
site and immediately surrounding areas. The native soils encountered at the test pit locations
are generally consistent with the soils within the transition zone between glacial till and advance
outwash deposits.
Groundwater
Groundwater seepage was not encountered at the time of exploration (November 2012).
Perched groundwater seepage zones are common along the contact between permeable soils
such as sand and lower permeability soils such as silt and clay. Groundwater seepage,
however, could be encountered locally within deeper excavations throughout the site, such as
the planned parking area excavation. 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 flow rates are higher during the wetter, winter months.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
CRITICAL AREAS ASSESSMENT
ES-2590
Page 3
As part of our report preparation, we assessed the site for potential instability relating to steep
slopes, landslide hazards and erosion hazards. We reviewed the online COR Map database on
the City of Renton website. Based on review of the GIS database, erosion hazard areas are
located on the western portion of the subject site, regulated slopes are mapped on portions of
the west property and landslide hazards are mapped on the eastern approximately one-half of
the property. Renton critical area regulations, Code Section 4-3-050 were reviewed as part of
this assessment.
Erosion Hazards
Erosion hazards were delineated along the steeper sloped areas of the site, generally along the
western margins. The USDA NRCS online resource indicates the approximate western one-
third of the site is underlain by Alderwood series (AgC) glacial till, 15 to 30 percent slopes and
the remainder of the site is underlain by Indianola (lnC) soils. The topography in this area
consists of a slope which descends from the existing yard area to Park Place North and North
26 1h Street. The slope ranges in height from about four feet and increases to the west to about
15 feet, with slope gradients generally in excess of 40 percent. The soils which comprise the
slope consist primarily of loose to medium dense silty sand and sand fill. We understand
grading in this area will be limited to establishing adequate foundation support. We understand
any grading along the steeper sloped areas of the site will be limited to enhancing stability by
removing yard waste and establishing more appropriate vegetation. In this respect, the project
envelope will be located outside the erosion hazard delineation and standard erosion and
sediment control BMPs will provide an adequate level of safety.
Landslide Hazards
The slopes along the south, west and part of the north property boundary are inclined at more
than 40 percent and range in height up to about 15 feet. Based on the conditions encountered
at the test pits in this area (TP-1, TP-2 and TP-4) the soils underlying the slope consist of
granular fill. Medium dense conditions were generally encountered at depths of about four to
five feet. In our opinion, the slopes would present a low landslide hazard. Final grading plans
must prevent water from ponding or flowing over the sloped areas of the site. With respect to
the mapped landslide hazard area, given the low existing topographic relief in the eastern one-
half of the site, this area would be considered a low landslide hazard.
Steep Slope Hazards
Based on review of the Renton Critical Areas maps, the descending slope bordering the south,
west and portions of the north property are mapped as Protected Slopes. The slopes were
created during past grading activities which consisted of placing fill to raise the site grades to
the current configuration and construction of the current rights-of-way alignments. We
understand no grading will take place on the protected slope areas other than possibly
revegetation.
Earth Solutions t#V, LLC
Conner Homes
December 4, 2012
Foundation Setbacks
ES-2590
Page4
In our opinion, new foundations should maintain a minimum setback of 15 feet from the top of
the descending slopes located along the south, west and north sides of the site. Fill should not
be placed between the foundations and the slopes. Decks may be placed between the new
foundations and top of descending sloped provided the foundations are drilled (to minimize
disturbance) and extend to a depth of at least ten feet. Property survey information was not
available at the time of this report, but in any case, foundation elements should not be placed
on the descending slope.
ESNW should review the final plans to confirm the recommendations and intent of this report
are followed and to provide additional recommendations.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our study, construction of the proposed residential short plat project is
feasible from a geotechnical standpoint. The primary geotechnical considerations associated
with the proposed development include excavation for the new residences, temporary slope
construction, foundation subgrade preparation and related earthwork for the building areas, and
protecting the sloped areas of the site. Open cut excavations for purposes of facilitating
construction of the new residential structures are feasible, in our opinion. Due to the presence
of fill, overexcavation of the existing fill will be necessary as part of preparing the foundation
subgrade for the building structures. Where existing fill, loose native soil, or otherwise
unsuitable conditions are present at subgrade elevations, the minimum structural fill depth
below foundations should be 24 inches. Recommendations for preparing the building
foundation subgrade and other pertinent geotechnical recommendations are provided in the
following sections of this report.
This geotechnical engineering study has been prepared for the exclusive use of Conner Homes
and their representatives. The study has been prepared specifically for the subject project. No
warranty, expressed or implied, is made. This study has been prepared in a manner consistent
with the level of care and skill ordinarily exercised by other members of the profession currently
practicing under similar conditions in this area.
Site Preparation and Earthwork
The primary geotechnical considerations with respect to earthwork are related to foundation
excavations, temporary slope construction and foundation subgrade preparation. The soil
conditions anticipated to be encountered within the j:>i'opo·sed building envel!)pes should largely
consist of existing fill (to depths of roughly 12 feet) and native sand soil deposits. The existing
fill contained little to no deleterious debris except minor organics and a f~latilieiy low fines
content. Soil relative density is generally expected to increase with depth. Although
groundwater seepage is not expected to be a major consideration during earthwork, the
contractor should be prepared to address possible grounclwater seepage issues during the
excavation phase, particularly within the planned excavation for·the underground parking level.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
Temporary Erosion Control
ES-2590
Page 5
In general, control of off-site erosion for this project will likely be limited to construction
entrances. Silt fencing should be installed as needed along the site perimeter. Construction
entrances should consist of quarry spalls underlain by a woven geotextile fabric such as Mirafi
500X. Quarry spall thickness will depend on subgrade stability at the entrance, but should
typically be at least 12 inches.
Expected Sequence of Earthwork
A schedule of earthwork activity and sequencing has not been produced at this time. However,
based on our current understanding of the project, the following should be considered for
sequencing the earthwork:
o Install erosion control measures and initiate parking garage excavation and temporary
slope construction (geotechnical engineer to confirm stability).
o Rough grade remainder of site to establish subgrade for at-grade and step foundations
(building structures). Overexcavate and establish minimum 24 inches of structural fill
below foundations (see following Foundation Subgrade Preparation section of this
study).
o Install perimeter drainage, backfill footing and foundation wall areas, and complete final
grading of the building envelope. Compaction testing of structural backfill soils, as
needed.
o Final landscaping and removal of temporary erosion control (at project completion).
Foundation Subgrade Preparation
Final site layout plans were not developed at the time of this report; however, given the current
topography across the site, grading is anticipated to be minimal. Given the presence of fill
across much of the site, new foundation areas should be overexcavated at least 24 inches and
compacted to a firm and unyielding condition and grades restored using suitable site soils
compacted to structural fill specifications provided in this report.
The following guidelines for preparing the building subgrade should be incorporated into the
final design:
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
ES-2590
Page 6
o In general, where voids and related demolition disturbances extend below the planned
building subgrade level, restoration of these areas should be completed as necessary.
Structural fill should be used to restore voids or unstable areas resulting from existing
building removal and site demolition activities.
o Following completion of rough grading, overexcavate stepped and at-grade foundations
areas (building structures) a minimum of 24 inches. The overexcavation shall extend
horizontally a minimum of one foot beyond the perimeter of the new foundation
elements. The subgrade shall be compacted to a firm and unyielding condition prior to
restoring grades with structural fill. Temporary slope excavations to accommodate the
recommended overexcavation shall be no steeper than 1 H:1V.
o ENSW shall observe the overexcavated surfaces. Supplement recommendations,
including additional overexcavation, may be provided based on observed conditions.
o Compact structural fill throughout foundation areas to at least 90 percent relative
compaction, based on the maximum dry density as determined by the Modified Proctor
Method.
o ESNW should confirm overall suitability of the prepared subgrade foundation and slab
subgrade areas following the site work activities.
Structural Fill
The native and suitable existing fill soils can be considered for use as structural fill, provided the
soil is at or near the optimum level at the time of placement. Silt soils are generally not
recommended for use as structural fill or wall backfill. The native and existing fill deposits
would be considered to have a moderate to high sensitivity to moisture. These deposits,
particularly the existing silty sand fill will become unstable if exposed to excessive moisture. If
the onsite soils cannot be successfully compacted, the use of an imported soil may be
necessary. Imported soil intended for use as structural fill should consist of a well graded
granular soil with a moisture content that is at or near the optimum level. 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 five percent or less defined as the percent passing the #200
sieve, based on the minus three-quarter inch fraction.
Fills placed in foundation and slab-on-grade areas, as well as wall backfill, utility trench backfill,
and throughout roadway areas are considered structural fill. In general, soils placed in
structural areas should be placed in maximum 12-inch lifts and compacted to a relative
compaction of 90 percent, based on the maximum dry density as determined by the Modified
Proctor Method (ASTM D-1557-02). Roadway subgrade, and areas within the right-of-way will
require 95 percent relative compaction. Utility trench backfill should be compacted to the
specifications of the controlling jurisdiction.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
Foundations
ES-2590
Page7
The foundation subgrade should be prepared as previously described in the Foundation
Subgrade Preparation section of this study. Stepped and at-grade foundations for the building
structures to be constructed at this site should be supported on a minimum of 24 inches of
structural fill. Provided the foundations are supported as described above, the following
parameters can be used for design:
o Allowable soil bearing capacity
o Coefficient of friction
o Passive resistance
2,500 psf
0.40
350 pcf (equivalent fluid)*
• Assumes foundations backfilled with structural fill
For short term wind and seismic loading, a one-third increase in the allowable soil bearing
capacity can be assumed. A factor-of-safety of 1.5 has been applied to the friction and passive
resistance values.
With structural loading as expected, total settlement in the range of 1.0 inch is anticipated, with
differential settlement of about 0.5 inch. ESNW should review the foundation plan and provide
supplement recommendations for foundation support. ESNW should also observe the prepared
foundation soils during construction to confirm soil conditions and the allowable soil bearing
capacity.
Retaining Walls
Retaining walls should be designed to resist earth pressures and applicable surcharge loads.
The following values should be used for design:
o Active earth pressure (yielding condition 35 pcf (equivalent fluid/ granular fill)
o At-rest earth pressure (restrained condition) 50 pcf
o Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution)
o Passive earth pressure 350 pct (equivalent fluid)
o Allowable soil bearing capacity 2,500 psf
o Coefficient of friction 0.40
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
ES-2590
Page 8
Additional surcharge loading from foundations, sloped backfill, or other loading should be
included in the retaining wall design. 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. ESNW should review retaining wall designs to confirm
that appropriate earth pressure values have been incorporated into the design and to provide
additional recommendations.
Retaining walls should be backfilled with free draining material that extends along the height of
the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall
backfill can consist of a less permeable soil, if desired. In lieu of free draining backfill, use of an
approved sheet drain material can 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, as appropriate. A perforated drain pipe should be
placed along the base of the wall, and connected to an appropriate discharge location. A
retaining wall drainage detail is provided on Plate 3.
Slab-On-Grade Floors
Slab-on-grade floors should be supported on a firm and unyielding subgrade consisting of at
least one foot of granular structural fill. Unstable or yielding areas of the subgrade should be
recompacted or overexcavated and replaced with suitable structural fill prior to construction of
the slab. A capillary break consisting of a minimum of four inches of free draining crushed rock
or gravel should be placed below the slab. The free draining material should have a fines
content of five percent or less (percent passing the #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. If a vapor barrier is used, it should consist of a
material specifically designed for that use and installed in accordance with the manufacturer's
specifications.
Drainage
Although groundwater seepage is not expected to be a significant consideration for this project,
minor perched groundwater should be anticipated in site excavations. Temporary measures to
control surface water runoff and groundwater during construction would likely involve
interceptor trenches and sumps. ESNW should be consulted during preliminary grading to
identify areas of seepage and to provide recommendations to reduce the potential for instability
related to seepage effects.
In our opinion, foundation drains should be installed along building perimeter footings. A
footing drain detail is provided on Plate 4.
Earth Solutions WV, LLC
Conner Homes
December 4, 2012
Excavations and Slopes
ES-2590
Page 9
The Federal and state Occupation Safety and Health Administration (OSHAIWISHA) classifies
soils in terms of minimum safe slope inclinations. In our opinion, based on the soil conditions
encountered during fieldwork for this site, the existing fill, loose native soil and where
groundwater is exposed would be classified by OSHAIWISHA as Type C. Temporary slopes
over four feet in height in Type C soils should be sloped at an inclination of 1.5H:1V, or flatter.
Below the existing fill deposits, the medium dense native soil deposits would be characterized
as Type 8. Temporary slopes in Type B soils should be sloped at an inclination of 1H:1V, or
flatter. ESNW should observe the excavations to confirm the appropriate allowable temporary
slope inclination. Additionally, guidelines for temporary slope construction related to the
planned underground garage level excavation are provided in the previous Site Preparation and
Earthwork section of this study. If temporary slope construction cannot be accomplished, the
use of temporary shoring may be required.
Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with an
appropriate species of vegetation to enhance stability and to minimize erosion.
Seismic Considerations
The 2009 International Building Code specifies several soil profiles that are used as a basis for
seismic design of structures. Based on the soil conditions observed at the test sites, Site Class
D, from table 1613.5.2, should be used for design. In our opinion, the site has a low
susceptibility to liquefaction. The absence of an established shallow groundwater table, and
the soil relative density observed throughout the test sites is the primary basis for this
conclusion.
Utility. Support and Trench Backfill
In our opinion, the soils observed at the boring locations are generally suitable for support of
utilities. Organic or highly compressible soils encountered in the trench excavations should not
be used for supporting utilities. The onsite soils observed at the test sites may be suitable for
use as structural backfill in the utility trench excavations, pending confirmation by the
geotechnical engineer. Moisture conditioning of the soils may be necessary prior to use as
structural fill. Where the onsite soils are determined to be unsuitable for use as structural fill,
use of a suitable imported granular soil may be necessary. The presence of groundwater could
be encountered in site excavations, such as the deeper utility trench excavations. Utility trench
backfill should be placed and compacted to the specifications of structural fill provided in this
report, or to the applicable specifications of the city or utility district jurisdictions.
Earth Solutions NW, LLC
Conner Homes
December 4, 2012
LIMITATIONS
ES-2590
Page 10
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. A warranty is not
expressed or implied. Variations in the soil and groundwater conditions identified at the test
sites may exist, and may not become evident until construction. ESNW should reevaluate the
conclusions 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. ESNW should also be retained to provide testing and
consultation services during construction.
Earth Solutlons NW, LLC
Reference:
King County, Washington
Map 626
By The Thomas Guide
Rand McNally
32nd Edition
Vicinity Map
Park Place Short Plat
Renton, Washington
NOTE: This plate may contain areas of color. ESNW cannot be Drwn. GLS Date 11/19/2012 Proj. No. 2590
responsible for any subsequent misinterpretation of the information
resulting from black & white reproductions of this plate. Checked SSR Date Nov. 2012 Plate 1
------I
I
I
I
-,_ ----------------------------.
200
I
I
I
N. 26TH STKEET
2 1° 220
I ',
/ \
I
I < / 7..-,,-----/ ---·-,·---r-\ I I / / .,.,. .,,.. --;ii-\ r ·--.... --.... ~-~~--i-·n -
I//'/// .,,..,,.--..,ITP-4 \ \ J 1 ,1 / ', ,' I '//2/30
I I I I/// r,,,. I I I J / t \ I I I /
!.J..; /II/Ill I ) J J / \ \ I lj/
(_) 1 111 1 11 1 I l I \ ! /
J ) / / / / / t[ I I \ \ f (".,,..,,.. \ \ : 1/' /
I ::i //11 1 1/..-.J.a-· I \ )// J I JI
I ' 1111,, 'ITP.1 / I II / I 1, /
190--/1 1111 1 ',', ' AppfOXimste , : : : /' , ; 1/ I
, ~ \ I : 1 u I I I : ; __ Top of, RegulatGd , I I I ( / , , 1' · ,,
"'< < I ( I -SI I 11 I 1, 0::: k ' , I J \ I l I IL', ' / ope I I I I \ 1, I I 0::: 11 I I I I I I I I I I I I I I I I I / 'l I
I
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: / / i: // //; \<--.,.~ A!Jproximt.la \ 1 1 : \ //11
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1
1 I/ /
11///1/1! Y. :--:i• I I
/
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11 1111, 1,,'-... // \ : ', 11111· /
I I / I 11 I J ', '' ' ' ...._ I I \ I I (
II '' ' '' ' ' . I IJ/ ,'..._,,,,,I. I I \ I\ ! r , , ',, , , , ' , , TP-2 1 \ / I 'J 1 I I l '', '',' ' '', ~t-I I I \ / ' Li.', I ',,,,,,,,,,~, I I I l \ 1/11 I
I --: .. > .... :.........) ~ ..... ~ ~--... ~----1....L.~·----~·~< -/ J ,, /
I ', -', (, ~
1J0 200 '1_ , ~
• 220 210 230
LEGEND
TP-1-f-Approximate Location of
ESNW Test Pit, Proj. No.
ES-2590, Nov. 2012 ,--,
L __ _J Subject Site
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.
1 "=40'
Test Pit Location Plan
Park Place Short Plat
Renton, Washington
Drwn. GLS Date 11/20/2012 Proj. No.
Checked SSR Date Nov. 2012 Plate
2590
2
18" Min. ~ <l------'----------1!>1.1
NOTES:
o Free Draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing #4 should be 25 to
75 percent.
o Sheet Drain may be feasible in lieu
of Free Draining Backfill, per ESNW
recommendations.
o Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1"
Drain Rock.
LEGEND:
Free Draining Structural Backfill
1 inch Drain Rock
Structural
Fill
SCHEMATIC ONLY· NOT TO SCALE
NOT A CONSTRUCTION DRAWING
RETAINING WALL DRAINAGE DETAIL
Park Place Short Plat
Renton, Washington
Drwn. GLS Date12/04/2012 Proj. No. 2590
Checked SSR Date Dec. 2012 Plate 3
Slope
I>
2" (Min.)
Perforated Rigid Drain Pipe
(Surround with 1" Rock)
NOTES:
o Do NOT tie roof downspouts
to Footing Drain.
o 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.
1" Drain Rock
SCHEMATIC ONLY-NOTTO SCALE
NOT A CONSTRUCTION DRAWING
Drwn. GLS
FOOTING DRAIN DETAIL
Park Place Short Plat
Renton, Washington
Date12/04/2012 Proj. No. 2590
Checked SSR Date Dec. 2012 Plate 4
APPENDIX A
SUBSURFACE EXPLORATION
ES-2590
The subsurface conditions at the site were explored by excavating four test pits to maximum
depths of 12.5 feet below existing grades. The approximate locations of the test pits are
illustrated on Plate 2 of this report. The test pit logs are provided in this Appendix of the report.
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
Earth Solutions NWLLc
SOIL CLASSIFICATION CHART
MAJOR DIVISIONS SYMBOLS
GRAPH LETTER
TYPICAL
DESCRI.PTIONS
COARSE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL IS
LARGER THAN
NO. 200 SIEVE
SIZE
FINE
GRAINED
SOILS
MORE THAN 50%
OF MATERIAL tS
SMALLER THAN
NO. 200 SIEVE
SIZE
GRAVEL
AND
GRAVELLY
SOILS
MORE THAN 50%
OF COARSE
FRACTION
RETAINED ON NO.
4SIEVE
SAND
AND
SANDY
SOILS
CLEAN
GRAVELS
GRAVELS WITH
FINES
(APPRECIABLE
AMOUNT OF FINES)
CLEAN SANDS
(LITTlE OR NO FINES)
SANDS WITH
MORE THAN SO% FINES
OF COARSE
FRACTION
PASSING ON NO,
4 SIEVE (APPRECIABLE
SILTS
AND
CLAYS
SILTS
AND
CLAYS
AMOUNT OF FINES)
LIQUID LIMIT
LESS THAN SO
LIQUID LIMIT
GREATER THAN !SO
HIGHLY ORGANIC SOILS
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
WELL-GRADED GRAVELS, GRAVEL-
SAND MIXTURES, LITTlE OR NO
FINES
POORLY-GRADED GRAVELS.
GRAVEL-SAND MIXTURES, LITTLE
OR NO FINES
SILTY GRAVELS, GRAVEL· SAND·
SILT MIXTURES
CLAYEY GRAVELS, GRAVEL·SAND-
CLAY MIXTURES
WELL-GRADED SANDS, GRAVELLY
SANDS, UTil.E OR NO FINES
POORLY-GRADED SANDS,
GRAVELLY SAND, LITTLE OR NO
FINES
SILTY SANDS, SAND-SILT
MIXTURES
CLAYEY SANDS, SAND-CLAY
MIXTURES
INORGANIC SILTS AND VERY FINE
SANDS, ROCK FLOUR, SIL TY OR
CLAVEY FINE SANDS OR CLAVEY
SILTS WrTH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLY
CLAYS, SANDY CLAYS, S1L1Y
CLAYS, LEAN CLAYS
ORGANIC SILTS AND ORGANIC ·
SILTY CLAYS OF LOW PLASTICITY
INORGANIC SIL TS, MICACEOUS OR
DIATOMACEOUS FINE SAND OR
SILTY SOILS
INORGANIC CLAYS OF HIGH
PLASTICITY
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICllY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
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 Jogs.
• Earth Solutions NW TEST PIT NUMBER TP-1
1805 136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton 1 Washington
DATE STARTED 11/5/12 COMPLETED 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES Deeth of Toesoil & Sod 6": y:ard grass AFTER EXCAVATION
w
:,: ~ ffi ui <J
li: 2 ~CD TESTS (.j ii: 8 MA TERI AL OESCRIPTION w-0.::. ui iii ..., 0 t~ :;j Cl
0
Brown silty SAND, loose, moist (Fill)
-scattered gravel
--
MC= 16.10%
---becomes medium dense
5 -variable silt content
~
I-. SM -becomes with gravel
I-MC= 10.20%
Fines = 15.20%
--asphalt pieces
'
_!Q__
~ -
12.0 --. -Brown silty SAND, medium dense, moist SM .. 12:5 MC= 14.90% Test pit tenninated at 12.5 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test pit at 12.5 feet.
• Earth Solutions NW TEST PIT NUMBER TP-2
1805 136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton 1 Washington
DATE STARTED 11/5112 COMPLETED 11/5112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ~
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES ...!1fillth of Togsoil & Sod 6": ~ard grass AFTER EXCAVATION --
w
0. C)
ii: "' ~ ffi ui :i:8 W III TESTS cj MATERIAL DESCRIPTION w-.., ::;; ui ~.., C 0.:, :;j !z C)
0
Brown silty SAND, loose, moist (Fill)
' . --scattered gravel
-fine roots
--
-asphalt pieces -
MC= 13.70% -becomes medium dense
--
,.....L
SM
f-. -asphalt pieces
" -
" ' MC= 11.70%
'
" '
...1Q_
10,5
MC= 11.70% SM 11.0 Gray brown silty SAND, medium dense, moist
Test pit terminated at 11.0 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test pit at 11.0 feet.
• Earth Solutions NW TEST PIT NUMBER TP-3
1805136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton, Was!![,ig!on
DATE STARTED 1115112 COMPLETED 1115112 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
' EXCAVATION METHOD AT TIME OF EXCAVATION -
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES Depth of Topsoil & Sod 6": ~ard grass AFTER EXCAVATION ~
w
~g
~ ffi en 0
i: (!) w a, TESTS t.i 0. 0 MATERIAL DESCRIPTION ..J :;; ~ ~..J C 0.:::, !z :::, (!)
o
SMG
Dark brown silty SAND, loose, wet (Fill)
2.0
Brown silty fine SAND, loose, moist
" .
" .
__L SM
.,
" . MC= 10.90%
< ·, 8.0 -. Test pit tenninated at.8.0 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test pi\ at 8.0 feet.
• Earth Solutions NW TEST PIT NUMBER TP-4
1805136th Place N.E., Suite 201 PAGE 1 OF 1
Bellevue, Washington 98005
Telephone: 425-284-3300
CLIENT Conner Homes PROJECT NAME Park Place Short Plat
PROJECT NUMBER 2590 PROJECT LOCATION Renton, Washington
DATE STARTED 11/5/12 COMPLETED 11/5/12 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION
LOGGED BY SSR CHECKED BY SSR AT END OF EXCAVATION
NOTES ..Qru11h of Topsoil & Sod 6": yaid grass AFTER EXCAVATION -
w a. 0
i:: ii,
~ ffi ui :i: Cl wa> TESTS q a.o MATERIAL DESCRIPTION w-..J:::; en ~..J C a.:::, :;; :l: z Cl
en
0
I Brown silty SAND, loose, moist (Fill)
-
. . SM
MC= 13.60%
Fines= 28.30%
~ 4.0 -asphalt pieces . . Brown flne SAND with slit, medium dense, moist
r-L SP-
SM
MC= 11.60% 6.0
Fines= 9.50% Test pit terminated at 6.0 feet below existing grade. No groundwater encountered during
excavation.
Bottom of test pit at 6.0 feet.
I l < t
APPENDIXB
LABORATORY TEST RESULTS
ES-2590
Earth Solutions NW, LLC
4 ' • •
Earth Solutions NW GRAIN SIZE DISTRIBUTION
1805-136th Place N.E., Suite 201
Bellevue, WA 98005
Telephone: 425-284-3300
CLIENT Conner H9m~s
PROJECT NUMBER ES-2590
U.S. SIEVE OPENING IN INCHES I
6432•1 1123183 ... 8
100
95
I ,~ ·1 I
. : '.,' I
90 ).___ \
85
80 .
75
70
!i:
65
C) 60 ~
~ 55
0:: w 50 z
ii:
>-45 z w
~ 40
w a.
35
30
25
20 ''
15
10
5
0
100 10
GRAVEL
PROJECT NAME Park Plaoe Short Pia)
PROJECT LOCATION Renton
U:S, SIEVE NUMBERS I
·e10 1415 20 .so 40 so 60 100140200
1 I I I I
:
\
!
" '
:
;
' \ .
·. \
:
) \ \
; ~ :
! \ :
\
\
~
: \
; '
1 0.1
GRAIN SIZE IN MILLIMETERS
HYDROMETER
0.01
SAND SILT OR CLAY COBBLES coarse fine coarse medium fine I
.
'
' -
0.001
Specimen Identification Classification LL PL Pl_· Cc Cu
~ 0 TP-1 7.0ft. Brown silty SAND with gravel, SM
~ 181 TP-4 3.0ft. Brown silty SAND with gravel, SM TP-4 6.0ft. Brown poorly graded SAND with silt, SP-SM 1.45 4.24 I" !!ll-+------+---~-------'-----------lc---+--+-+~+'-'--1
!.~----'--1---~-~~~~---,-~-'-"<-'--'-'--'--',,--L--'-i-~--l a D10 %Gravel %Sand %Silt %Clay
& 22.9 61.9 15.2
!~:=========~~~=:===~==:======~======~======~~=~2~8-=0=~~==4~3-=8==~=====2~8=.3=====~ ~ 0.081 8.7 81,7 9.5 ~1-1~-------'-'-lf--..:.C..-+-----+-----+~---1---~f--~--1-----------1
Speci_men Identification. D100 D60 D30
0 TP-1 7.0ft.' 37.5 1.121 0.241
181 TP-4 3.0ft. 19 1.307 0.094
" TP-4 6.0ft. 37.5 0.343 0.201
IL...L..---"'"---'-----'---'---'---L------L---.1.----L------'
~ I ' •·
EaMAILCOPY
REPORT DISTRIBUTION
ES-2590
Conner Homes
846 -·1081h Avenue Northeast
Bellevue, Washington 98004
Attention: Mr. Rob Risinger
Earth Solutions NW, LLC
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