HomeMy WebLinkAboutEx_10_TIR
Western Washington Division Eastern Washington Division
165 NE Juniper St., Ste 201, Issaquah, WA 98027 407 Swiftwater Blvd, Cle Elum, WA 98922
Phone: (425) 392-0250 Fax: (425) 391-3055 Phone: (509) 674-7433 Fax: (509) 674-7419
www.EncompassES.net
PRELIMINARY TECHNICAL INFORMATION REPORT
For
Peck Short Plat
11086 SE 192nd Street
Renton, WA 98056
January 28th, 2025
Prepared by:
Gabe Garner
Encompass Engineering Job No. 23734
Prepared For:
Daniel Peck
Lake Samish, LLC
7710 203rd Street SE
Snohomish, WA 98296
Exhibit 10
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | i
Table of Contents
List of Figures ................................................................................................................................... i
I. PROJECT OVERVIEW ................................................................................................................ 1
II. CONDITIONS AND REQUIREMENTS SUMMARY ...................................................................... 7
III. DOWNSTREAM ANALYSIS ...................................................................................................... 11
IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ........................... 15
V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ..................................................................... 18
VII. OTHER PERMITS ..................................................................................................................... 18
VIII. CSWPP ANALYSIS AND DESIGN .............................................................................................. 18
IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION of COVENANT .................. 18
X. OPERATION AND MAINTENANCE MANUAL .......................................................................... 18
List of Figures
Figure 1 – TIR Worksheet
Figure 2 – Vicinity Map
Figure 3 – Soils Map and Legend
Figure 4 – Existing Conditions Map
Figure 5 – Developed Conditions Map
Figure 6 – Drainage Review Flow Chart
Figure 7 – Downstream Map
Appendix A
Geotechnical Engineering Study by Earth Solutions NW, LLC dated February 21, 2024
Appendix B
Wetland Reconnaissance by Altmann Oliver Associates, LLC dated June 12, 2024
Appendix C
Arborist Report by Layton Tree Consulting, LLC dated March 27, 2024, Updated September 3, 2024
Appendix D
WWHM Output
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Project Owner
Phone _____
Address
Project Engineer
Company ____
Phone _______
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Name _
DLS-Permitting
Permit #_____
Location Township
Range _
Section _
Site Address _______
Part 3 TYPE OF PERMIT APPLICATION
□ Land use (e.g.,Subdivision / Short Subd. / UPD)
□ Building (e.g.,M/F / Commercial / SFR)
□ Clearing and Grading
□ Right-of-Way Use
□ Other ___________________________
Part 4 OTHER REVIEWS AND PERMITS1
□ DFW HPA
□ COE CWA 404
□ ECY Dam Safety
□ FEMA Floodplain
□ COE Wetlands
□ Other _________
□ Shoreline
Management
□ Structural
Rockery/Vault/______
□ ESA Section 7
Part 5 PLAN AND REPORT INFORMATION
Technical Information Report
Type of Drainage Review
(check one):
Date (include revision
dates):
Date of Final:
□
□
□
□
□
Full
Targeted
Simplified
Large Project
Directed
Site Improvement Plan (Engr. Plans)
Plan Type (check
one):
Date (include revision
dates):
Date of Final:
□ Full
□ Modified
□ Simplified
Part 6 SWDM ADJUSTMENT APPROVALS
Type (circle one): Standard / Experimental /Blanket
Description: (include conditions in TIR Section 2)
Approved Adjustment No._ _ Date of Approval: __________________________
1 DFW: WA State Dept. of Fish and Wildlife. HPA: hydraulic project approval. COE: (Army) Corps of Engineers. CWA: Clean
Water Act. ECY: WA State Dept. of Ecology. FEMA: Federal Emergency Management Agency. ESA: Endangered Species Act.
2021 Surface Water Design Manual
1
Last revised 7/23/2021
Daniel Peck
206-660-6241
7710 203rd Street SE
Snohomish, WA 98296
Chad Allen
Encompass Engineering
425-961-2160
Peck Short Plat
TBD
23N
5E
SW33
11086 SE 192nd Streert
Renton, WA 98056
4
4
4
4
01/28/2025 01/28/2025
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 7 MONITORING REQUIREMENTS
Monitoring Required: Yes / No
Start Date:
Describe:
Completion Date:Re: KCSWDM Adjustment No.
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Community Plan :________________________________
Special District Overlays:_________________________
Drainage Basin:__________________________________
Stormwater Requirements: _______________________
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
□ River/Stream □Steep Slope
□ Lake □Erosion Hazard
□ Wetlands □Landslide Hazard
□ Closed Depression □Coal Mine Hazard
□ Floodplain □Seismic Hazard
□ Other □Habitat Protection
□
Part 10 SOILS
Soil Type Slopes Erosion Potential
□ High Groundwater Table (within 5 feet) □ Sole Source Aquifer
□ Other______________ _______________________ □ Seeps/Springs
□ Additional Sheets Attached
2021 Surface Water Design Manual
2
Last revised 7/23/2021
None
None
Soos Creek
Small Subdivision Project BMP Requirements
Alderwood gravelly
sandy loam
0-2%Low
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE LIMITATION / SITE CONSTRAINT
□ Core 2 - Offsite Analysis____________________ _________________________________
□ Sensitive/Critical Areas_____________________ _________________________________
□ SEPA_____________________________________ _________________________________
□ LID Infeasibility____________________________ _________________________________
□ Other_____________________________________ _________________________________
□
□ Additional Sheets Attached
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area)
Threshold Discharge Area:
(name or description)
Core Requirements (all 8 apply):
Discharge at Natural Location Number of Natural Discharge Locations:
Offsite Analysis Level: 1 / 2 / 3 dated:
Flow Control (include facility Level: 1 / 2 / 3 or Exemption Number ______________
summary sheet)Flow Control BMPs
Conveyance System Spill containment located at:
Erosion and Sediment Control /CSWPP/CESCL/ESC Site Supervisor:
Construction Stormwater
Pollution Prevention Contact Phone:
After Hours Phone:
Maintenance and Operation Responsibility (circle one): Private / Public
If Private, Maintenance Log Required: Yes / No
Financial Guarantees and
Liability
Provided: Yes / No
Water Quality (include facility Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog
summary sheet)or Exemption No.
Landscape Management Plan: Yes / No
For Entire Project:Total Replaced Impervious surfaces on the site
% of Target Impervious that had a
feasible FCBMP
Total New Pervious Surfaces on the site
Repl. Imp. on site mitigated w/flow control facility
implemented Repl. Imp. on site mitigated w/water quality facility
Repl. Imp. on site mitigated with FCBMP
2021 Surface Water Design Manual
3
Last revised 7/23/2021
Duwamish - Green River
1
09/19/2024
TBD
TBD
TBD
TBD
0%
22,576 SF
42,689 SF
22,576 SF
22,576 SF
0 SF
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area)
Special Requirements (as applicable):
Area Specific Drainage
Requirements
Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None
Name:
Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities Describe:
Source Control
(commercial / industrial land use)
Describe land use:
Describe any structural controls:
Oil Control High-use Site: Yes / No
Treatment BMP:
Maintenance Agreement: Yes / No
with whom?
Other Drainage Structures
Describe:
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
^ Clearing Limits
^ Cover Measures
^ Perimeter Protection
^ Traffic Area Stabilization
^ Sediment Retention
^ Surface Water Collection
^ Dewatering Control
^ Dust Control
^ Flow Control
^ Protection of Flow Control BMP Facilities
(existing and proposed)
^ Maintain BMPs / Manage Project
MINIMUM ESC REQUIREMENTS
AFTER CONSTRUCTION
^ Stabilize exposed surfaces
^ Remove and restore Temporary ESC Facilities
^ Clean and remove all silt and debris, ensure
operation of Permanent Facilities, restore
operation of Flow Control BMP Facilities as
necessary
^ Flag limits of SAO and open space preservation
areas
^ Other
2021 Surface Water Design Manual
4
Last revised 7/23/2021
None
Residential
N/A
4
4
4
4
4
4
4
4
4
4
4
4
4
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch)
Flow Control Type/Description Water Quality Type/Description
□ Detention □Vegetated Flowpath
□ Infiltration □Wetpool
□ Regional Facility □Filtration
□ Shared Facility □Oil Control
□ Flow Control BMPs □Spill Control
□ Other □Flow Control BMPs
□Other
Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS
□ Drainage Easement □ Cast in Place Vault
□ Covenant □ Retaining Wall
□ Native Growth Protection Covenant □ Rockery > 4’ High
□ Tract □ Structural on Steep Slope
□ Other □ Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information provided here is accurate.
Signed/Date
2021 Surface Water Design Manual
5
Last revised 7/23/2021
4
4
4
4
Contech CMP
Chad Allen 01/28/2025
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 1
I. PROJECT OVERVIEW
Project: Peck Short Plat
Site Address: 11806 SE 192nd Street, Renton, WA 98056 (See Vicinity Map)
Tax Parcel #: 619840-0360
Zoning District: R-4 (Single-Family Residential)
Site Area: 97,684 SF (2.24 AC) – per survey
Site Location: The site is in the City of Renton within the SW quarter of Section 33,
Township 23 North, Range 5 East, W.M, King County, Washington. The
site is located on the north side of SE 192nd Place, west of the intersection
of 120th Ave SE & 120th Ave SE.
Figure 2: Vicinity Map
Pre-developed Site Conditions:
The project site is located in the City of Renton on a 97,684 SF (2.24 AC) lot that is zoned R-4 (single-family
residential). The property is accessed from SE 192nd Street in the southern portion of the site. The site is
bordered to the east, west, and north by single-family residences, and to the south by SE 192nd Street. The
site is currently developed with a single-family residence accessed from SE 192nd Street via a gravel
driveway on the southern side of the site. The property is located within the Soos Creek drainage basin,
within the Duwamish - Green River watershed. Runoff exits the site from one natural discharge area (NDA)
located in the southeastern portion of the site, where runoff sheet flows towards SE 192nd Street and
enters the City of Kent’s storm system. Stormwater is ultimately discharged to Big Soos Creek, located
approximately 0.5 miles east of the site. See full downstream analysis in Section III of this Technical
Information Report (TIR).
An Existing Conditions Map is included as Figure 4 at the end of this Section.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 2
Critical Areas:
According to King County iMap, there are no environmentally sensitive areas located on or adjacent to
the subject site.
Soils:
Per the US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) Web Soil
Survey (WSS) information, the entire project site is underlain with Alderwood gravelly sandy loam, 0 to 8
percent slopes (See Figure 3 below). A Geotechnical Engineering Study prepared by Earth Solutions NW
(Appendix A) confirms this classification, as their soil test pits identified dense fill soils throughout the site
with groundwater seepage occurring 2-3 FT beneath the surface. Based on these geotechnical findings,
infiltration has been deemed infeasible for this project.
Figure 3: Soil Map and Legend
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 3
Developed Site Conditions
The project proposes the development of six (6) single-family lots within the 97,684 SF (2.24 AC) parcel.
Lot 1 is 9,418 SF and is proposed along the southern portion of the site, Lot 2 is 9,532 SF and is proposed
in the southwestern portion of the site, Lot 3 is 10,137 SF and proposed in the northwestern portion of
the site, Lot 4 is 9,302 SF and is proposed along the northern portion of the site, Lot 5 is 9,288 SF and is
proposed along the northern portion of the site, and Lot 6 is 15,889 SF and is proposed in the northeastern
portion of the site. A 9,654 SF storm tract is proposed in the southeastern portion of the site. A 24,465 SF
right-of-way (ROW) dedication is proposed within the site frontage and throughout the central portion of
the site to provide access to all six (6) lots.
The parcel is zoned R-4, which allows for a maximum building coverage of 35% and a maximum impervious
surface coverage of 50%. For the preliminary design of the lots, the maximum impervious surface
coverage was assumed.
• Lot 1: The maximum allowable impervious surface coverage for Lot 1 is 9,418 SF * 0.50 = 4,709
SF. The final site layout of Lot 1 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 1 will use
the maximum coverage stated above (4,709 SF).
• Lot 2: The maximum allowable impervious surface coverage for Lot 2 is 9,532 SF * 0.50 = 4,766
SF. The final site layout of Lot 2 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 2 will use
the maximum coverage stated above (4,766 SF).
• Lot 3: The maximum allowable impervious surface coverage for Lot 3 is 10,137 SF * 0.50 = 5,069
SF. The final site layout of Lot 3 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 3 will use
the maximum coverage stated above (5,069 SF).
• Lot 4: The maximum allowable impervious surface coverage for Lot 4 is 9,302 SF * 0.50 = 4,651
SF. The final site layout of Lot 4 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 4 will use
the maximum coverage stated above (4,651 SF).
• Lot 5: The maximum allowable impervious surface coverage for Lot 5 is 9,288 SF * 0.50 = 4,644
SF. The final site layout of Lot 5 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 5 will use
the maximum coverage stated above (4,644 SF).
• Lot 6: The maximum allowable impervious surface coverage for Lot 6 is 15,889 SF * 0.50 = 7,945
SF. The final site layout of Lot 6 has not been determined at this stage; therefore, this report
assumes that the future impervious surfaces required to construct the residence on Lot 6 will use
the maximum coverage stated above (7,945 SF).
• ROW Dedication: The ROW dedication proposes a total of 14,230 SF asphalt roadway.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 4
In total, this project proposes 14,230 SF of asphalt roadway, 7,622 SF of concrete sidewalk/aprons/ramps,
and a 724 SF of gravel access road (for access of the existing cell tower in the northeastern portion of the
site). This is a total of 22,576 SF of proposed impervious surfaces.
Stormwater runoff from the proposed surfaces within Lots 1-6 (when developed) and the ROW Dedication
will be collected and conveyed to a 70.5 FT x 69 FT Contech CMP detention tank with a 90” diameter
located within the stormwater tract in the southeastern corner of the site. Please refer to Core
Requirement #9 in Section II and Section IV of this TIR for additional discussion on stormwater BMPs and
flow control. A Developed Conditions Map is provided as Figure 5 at this end of this Section.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
SE 192ND ST
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EXISTING ON-SITE IMPERVIOUS COVERAGE:
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
SE 192ND ST
ROW DEDICATION
STORM TRACT
LOT 6LOT 5LOT 4LOT 3
LOT 1LOT 2
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PROPOSED ON-SITE IMPERVIOUS COVERAGE:
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 7
II. CONDITIONS AND REQUIREMENTS SUMMARY
The 2022 City of Renton Surface Water Design Manual (RSWDM) was utilized to determine and address
all core and special requirements. Based on the criteria specified in Figure 1.1.2.A of the RSWDM, the
project falls under Full Drainage Review. Per Section 1.1.2.4 of the RSWDM, the project must meet all nine
(9) core and all six (6) special requirements. See Figure 6 below for more information on how the type of
drainage review was determined.
Figure 6: Drainage Review Flow Chart
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 8
Core Requirements
Core Requirement #1: Discharge at the Natural Location
Runoff from the proposed development will follow existing drainage patterns. The project
proposes a Contech CMP detention tank which will connect back into the storm system within SE
192nd Street. This matches the drainage patterns in the existing conditions. Please refer to the full
Downstream Analysis provided in Section III of this TIR.
Core Requirement #2: Downstream Analysis
A Level 1 Downstream analysis has been completed for the site and no existing or potential
problems have been identified. This analysis is included in Section III of this TIR.
Core Requirement #3: Flow Control Facilities
Based on the City of Renton’s flow control application map, the project site is located within the
Duration Flow Control Standard (Forested Conditions). Flow control facilities are required to
match the developed peak discharge rates to historical (forested) site conditions over the range
of flows extending form 50% of the 2-year up to the full 50-year flow and match the peaks for the
2- and 10-year return periods.
A 70.5 FT x 69 FT Contech CMP detention tank with a 90” diameter is proposed to meet
stormwater requirements. This stormwater facility will be located in the southeast corner of the
site within the stormwater tract. Please refer to Section IV of this TIR for additional discussion.
Core Requirement #4: Conveyance System
Conveyance in compliance with the requirements detailed in Section 1.2.4.1 of the City of Renton
2022 SWDM is provided in Section V of this report.
Core Requirement #5: Construction Stormwater Pollution Prevention
A temporary erosion and sediment control (TESC) plan providing details on best management
practices (BMPs) to be implemented during construction is included in the engineering plan set.
A Construction Stormwater Pollution Prevention Plan (CSWPPP) will be provided with final
engineering. Please refer to Section VIII of this TIR for additional discussion.
Core Requirement #6: Maintenance and Operations
An Operation and Maintenance Manual will be provided with final engineering.
Core Requirement #7: Financial Guarantees and Liability
The owner will arrange for any financial guarantees and liabilities required by the permit.
Core Requirement #8: Water Quality Facilities
In accordance with Section 1.2.8.1.A of the RSWDM, Basic Water Quality Treatment is required
for this project as new plus replaced pollution generating impervious surfaces (PGIS) exceed 5,000
SF. To address water quality requirements, a Contech StormFilter catch basin is proposed post-
detention.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck Short Plat Preliminary Technical Information Report
01/28/2025 P a g e | 9
Core Requirement #9: Flow Control BMPs
This project is classified as a small subdivision; therefore, it is subject to the Small Subdivision
Project BMP Requirements detailed in Section 1.2.9.3.1 in the RSWDM. Although implementation
of individual lot BMPs is not required until building permit application, BMPs have been
considered for the future improvements on Lots 1-6 based on Section 1.2.9.2 and of the RSWDM.
See Section IV of this TIR for further discussion and flow control analysis.
Impervious Surface BMPs
The maximum impervious surface coverage allowed per zoning is 50%. For the design of the lots,
the maximum impervious surface coverage was assumed while evaluating future stormwater
BMPs. Their final location and design shall be determined under the single-family building permit
process.
Full Dispersion: Infeasible. A 100-foot native vegetated flowpath segment is not available on any
of the proposed lots.
Full Infiltration: Infeasible. The Geotechnical Engineering Study prepared by Earth Solutions NW
(Appendix A) states that their soil test pits identified dense fill soils throughout the site with
groundwater seepage occurring 2-3 FT beneath the surface. Based on these geotechnical findings,
infiltration has been deemed infeasible for this project.
Limited Infiltration: Infeasible. The Geotechnical Engineering Study prepared by Earth Solutions
NW (Appendix A) states that their soil test pits identified dense fill soils throughout the site with
groundwater seepage occurring 2-3 FT beneath the surface. Based on these geotechnical findings,
infiltration has been deemed infeasible for this project.
Rain Gardens/Bioretention: Infeasible. The Geotechnical Engineering Study prepared by Earth
Solutions NW (Appendix A) states that their soil test pits identified dense fill soils throughout the
site with groundwater seepage occurring 2-3 FT beneath the surface. Based on these geotechnical
findings, infiltration has been deemed infeasible for this project.
Permeable Pavement: Infeasible. The Geotechnical Engineering Study prepared by Earth Solutions
NW (Appendix A) states that their soil test pits identified dense fill soils throughout the site with
groundwater seepage occurring 2-3 FT beneath the surface. Based on these geotechnical findings,
infiltration has been deemed infeasible for this project.
Basic Dispersion: Basic Dispersion may be feasible on the proposed lots, depending on the building
footprints/layout for the future single-family residences. For now, it has been deemed infeasible
and all runoff has been designed to be directed into the proposed detention tank.
As no BMPs are feasible, stormwater runoff from the proposed surfaces within Lots 1-6 (when developed)
and the ROW Dedication will be collected and conveyed to a 70.5 FT x 69 FT Contech CMP detention tank
with a 90” diameter located within the stormwater tract in the southeastern corner of the site. Please
refer to Section IV of this TIR for additional information on the detention tank. A Developed Conditions
Map is provided as Figure 5 at this end of this Section.
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Special Requirements
Special Requirement #1: Other Adopted Area-Specific Requirements
Critical Drainage Area – N/A
Master Drainage Plan – N/A
Basin Plan – N/A
Lake management Plan – N/A
Shared Facility Drainage Plan – N/A
Special Requirement #2: Flood Hazard Area Delineation
The limits of this project do not lie within a delineated FEMA 100-year floodplain.
Special Requirement #3: Flood Protection Facilities
This project does not rely on or propose to modify/construct a new flood protection facility.
Special Requirement #4: Source controls
Source controls for the proposed short plat development are not applicable.
Special Requirement #5: Oil Control
This project is not considered high-use in need of oil control.
Special Requirement #6: Aquifer Protection Area
The site is not located within an Aquifer Protection Area per the Groundwater Protection Areas
Map in the RSWDM.
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III. DOWNSTREAM ANALYSIS
A Level 1 Downstream analysis has been conducted per the requirements in Section 1.2.2.1 of the
RSWDM. Please see Tasks 1 through 4 below for a summary of the results.
Task 1: Define and Map the Study Area
The area of analysis extends approximately a quarter-mile downstream from the natural discharge area
(NDA). This site includes one NDA in the southeastern portion of the site, therefore creating one threshold
discharge area. A Downstream Map is provided in Figure 7 below.
Figure 7: Downstream Map
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Task 2: Review All Available Information on the Study Area
Per King County resources, there have been no significant drainage complaints within a quarter-mile
downstream of the site.
Task 3: Field Inspect the Study Area
A field inspection was performed by Encompass Engineering & Surveying on September 19th, 2024. Please
refer to Task 4 for a detailed description of the downstream drainage system and analysis.
Task 4: Describe the Drainage System
Runoff from the site leaves from one natural discharge location in the southeastern portion of the site,
resulting in one threshold discharge area. Stormwater from the site begins by sheet flowing over minimal
grades of 0-2% towards the southeastern corner of the site (A). Once exiting the site, the runoff enters a
catch basin located in the right-of-way for SE 196th Street (B). This catch basin directs the runoff south
beneath SE 196th Street, where it is discharged on the southern side of the street via an 18” CMP culvert
(C). From here, the runoff sheet flows to the south through residential properties until the ¼ mile
downstream limit is reached. The ¼ mile limit is roughly where Glenridge Elementary School is located.
The runoff is assumed to enter a detention pond located downstream of the elementary school (D). No
drainage related issues were observed downstream of the site, and no relevant drainage complaints were
identified on the King County iMap system within a quarter mile of the site discharge location. Please refer
to Figure 7 above, for the approximate location of identified drainage features. Photographs from the site
visit are included below.
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Element A – Runoff sheet flows towards the southeastern corner of the site
Element B – Runoff enters stormwater system in SE 192nd St. (CB covered with vegetation)
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Element C – Storm system directs runoff south across SE 192nd St. to an 18” CMP culvert
Element D – Runoff enters detention pond south of Glenridge Elementary School
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IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN
Part A: Existing Site Hydrology
This property is located within the Soos Creek drainage basin, within the Duwamish - Green River
watershed. The 97,684 SF (2.24 AC) site is currently developed with a single-family residence accessed
from SE 192nd Street via a gravel driveway on the southern side of the site. Runoff exits the site from one
natural discharge area (NDA) located in the southeastern portion of the site, where runoff sheet flows
towards SE 192nd Street and enters the City of Kent’s storm system. Stormwater is ultimately discharged
to Big Soos Creek, located approximately 0.5 miles east of the site. See the full downstream analysis in
Section III of this Technical Information Report (TIR).
The Geotechnical Engineering Study prepared by Earth Solutions NW (Appendix A) confirms the NRCS
Alderwood gravelly sandy loam soil classification and has determined that infiltration BMPs are infeasible
for the project.
Part B: Developed Site Hydrology
The project proposes the development of six (6) single-family lots within the 97,684 SF (2.24 AC) parcel.
Lot 1 is 9,418 SF and is proposed along the southern portion of the site, Lot 2 is 9,532 SF and is proposed
in the southwestern portion of the site, Lot 3 is 10,137 SF and proposed in the northwestern portion of
the site, Lot 4 is 9,302 SF and is proposed along the northern portion of the site, Lot 5 is 9,288 SF and is
proposed along the northern portion of the site, and Lot 6 is 15,889 SF and is proposed in the northeastern
portion of the site. A 9,654 SF storm tract is proposed in the southeastern portion of the site. A 24,465 SF
right-of-way (ROW) dedication is proposed within the site frontage and throughout the central portion of
the site to provide access to all six (6) lots.
In total, this project proposes 14,230 SF of asphalt roadway, 7,622 SF of concrete sidewalk/aprons/ramps,
and a 724 SF of gravel access road (for access of the existing cell tower in the northeastern portion of the
site). This is a total of 22,576 SF of proposed impervious surfaces.
Stormwater runoff from the proposed surfaces within Lots 1-6 (when developed) and the ROW Dedication
will be collected and conveyed to a 70.5 FT x 69 FT Contech CMP detention tank with a 90” diameter
located within the stormwater tract in the southeastern corner of the site..
WWHM 2012 was used to model the proposed condition using target surfaces per Section 1.2.3 of the
2022 RSWDM. A summary of the existing and developed analyses is provided in the table below on the
following page. It should be noted that approximately 1,476 SF of proposed asphalt widening cannot be
captured and conveyed through the proposed detention tank. Therefore, an area swap diagram has been
depicted on the proposed condition map that shows the detention tank will be picking up an additional
3,526 SF of existing roadway. This additional area of existing asphalt has been considered in the modeling
for the detention tank.
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Existing Developed
Condition Measured Modeled Measured Modeled
C, Forest, Flat: 2.24 AC 2.24 AC
C, Lawn, Flat: 0.98 AC 0.98 AC
Roof Tops, Flat: 0.73 AC 0.73 AC
Roads, Flat: 0.39 AC 0.39 AC
Sidewalks, Flat: 0.14 AC 0.14 AC
Total Area: 2.24 AC 2.24 AC 2.24 AC 2.24 AC
WWHM Conditions Model
Part C: Performance Standards
Based on the City of Renton’s flow control application map, the project site is located within the Duration
Flow Control Standard (Forested Conditions). Flow control facilities are required to match the developed
peak discharge rates to historical (forested) site conditions over the range of flows extending form 50% of
the 2-year up to the full 50-year flow and match the peaks for the 2- and 10-year return periods.
This project is classified as a small subdivision; therefore, it is subject to the Small Subdivision Project BMP
Requirements detailed in Section 1.2.9.3.1 in the RSWDM. Although implementation of individual lot
BMPs is not required until building permit application, BMPs have been considered for the future
improvements on Lots 1-3 based on Section 1.2.9.2 and of the RSWDM. The site falls within a Basic Water
Quality treatment area in accordance with Section 1.2.8.1.A of the RSWDM.
Part D: Flow Control System
Flow control will be provided by a 70.5 FT x 69 FT Contech CMP detention tank with a 90” diameter located
within the stormwater tract in the southeastern corner of the site. The tank will discharge runoff into a
54” control structure post-detention. A Contech StormFilter catch basin is proposed after the control
structure in order to provide water quality for the pollution generating impervious surfaces. Per WWHM
modeling, the required storage volume of the system is 28,663 CF. The proposed tank has a provided
volume of 28,724 CF. The required volume that was produced from WWHM was utilized in the Contech
CMP Detention System Design Tool in order to get an accurate system sized. Please refer to Appendix B
for a copy of the full WWHM data output. See WWHM data inputs for detention system below:
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Part E: Water Quality System
In accordance with Section 1.2.8.1.A of the RSWDM, Basic Water Quality Treatment is required for this
project as new plus replaced pollution generating impervious surfaces (PGIS) exceed 5,000 SF. To address
water quality requirements, a Contech StormFilter catch basin is proposed post-detention. See the
engineering plans for the specifications of the storm filter.
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V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN
Conveyance system analysis and design will be completed with final engineering.
VI. SPECIAL REPORTS AND STUDIES
• Geotechnical Engineering Study by Earth Solutions NW, LLC dated February 21, 2024
• Wetland Reconnaissance by Altmann Oliver Associates, LLC dated June 12, 2024
• Arborist Report by Layton Tree Consulting, LLC dated March 27, 2024, Updated September 3,
2024
VII. OTHER PERMITS
• Civil Construction Permit
• Building Permits
• Right-of-Way Use Permit
VIII. CSWPP ANALYSIS AND DESIGN
A CSWPPP will be provided with final engineering.
IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION of
COVENANT
Bond Quantities, Facility Summaries, and a Declaration of Covenant will be provided with final
engineering.
X. OPERATION AND MAINTENANCE MANUAL
An Operation and Maintenance Manual will be provided with final engineering.
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Appendix A
Geotechnical Engineering Study by Earth Solutions NW, LLC dated February 21, 2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
EarthSolutionsNWLLC
EarthSolutionsNWLLC
Geotechnical Engineering
Construction Observation/Testing
Environmental Services
15365 NE 90th Street,Suite 100 •Redmond,WA 98052 •(425)449-4704
3130 Varney Lane,Suite 105 •Pasco,WA 99301 •(509)905-0275
esnw.com
GEOTECHNICAL ENGINEERING STUDY
PROPOSED BALES PLACE SHORT PLAT
11806 SOUTHEAST 192 STREET
RENTON,WASHINGTON
ES-9583
ND
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
PREPARED FOR
LAKE SAMISH, LLC
February 21, 2024
_______________________
John M. Neer, G.I.T.
Staff Geologist
_______________________
Henry T. Wright, P.E.
Associate Principal Engineer
GEOTECHNICAL ENGINEERING STUDY
PROPOSED BALES PLACE SHORT PLAT
11806 SOUTHEAST 192ND STREET
RENTON, WASHINGTON
ES-9583
Earth Solutions NW, LLC
15365 NE 90th Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704
3130 Varney Lane, Suite 105 • Pasco, WA 99301 • (509) 905-0275
esnw.com
02/21/2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Geotechnical-Engineering Report
Important Information about This
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, you can benefit from a lowered exposure to problems associated with subsurface conditions at project sites and development of them that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Active engagement in GBA exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project.
Understand the Geotechnical-Engineering Services Provided for this ReportGeotechnical-engineering services typically include the planning, collection, interpretation, and analysis of exploratory data from widely spaced borings and/or test pits. Field data are combined with results from laboratory tests of soil and rock samples obtained from field exploration (if applicable), observations made during site reconnaissance, and historical information to form one or more models of the expected subsurface conditions beneath the site. Local geology and alterations of the site surface and subsurface by previous and proposed construction are also important considerations. Geotechnical engineers apply their engineering training, experience, and judgment to adapt the requirements of the prospective project to the subsurface model(s). Estimates are made of the subsurface conditions that will likely be exposed during construction as well as the expected performance of foundations and other structures being planned and/or affected by construction activities.
The culmination of these geotechnical-engineering services is typically a geotechnical-engineering report providing the data obtained, a discussion of the subsurface model(s), the engineering and geologic engineering assessments and analyses made, and the recommendations developed to satisfy the given requirements of the project. These reports may be titled investigations, explorations, studies, assessments, or evaluations. Regardless of the title used, the geotechnical-engineering report is an engineering interpretation of the subsurface conditions within the context of the project and does not represent a close examination, systematic inquiry, or thorough investigation of all site and subsurface conditions.
Geotechnical-Engineering Services are Performed for Specific Purposes, Persons, and Projects, and At Specific TimesGeotechnical engineers structure their services to meet the specific needs, goals, and risk management preferences of their clients. A geotechnical-engineering study conducted for a given civil engineer
will not likely meet the needs of a civil-works constructor or even a
different civil engineer. Because each geotechnical-engineering study
is unique, each geotechnical-engineering report is unique, prepared solely for the client.
Likewise, geotechnical-engineering services are performed for a specific
project and purpose. For example, it is unlikely that a geotechnical-
engineering study for a refrigerated warehouse will be the same as
one prepared for a parking garage; and a few borings drilled during
a preliminary study to evaluate site feasibility will not be adequate to
develop geotechnical design recommendations for the project.
Do not rely on this report if your geotechnical engineer prepared it:
• for a different client;
• for a different project or purpose;
• for a different site (that may or may not include all or a portion of
the original site); or
• before important events occurred at the site or adjacent to it;
e.g., man-made events like construction or environmental
remediation, or natural events like floods, droughts, earthquakes,
or groundwater fluctuations.
Note, too, the reliability of a geotechnical-engineering report can
be affected by the passage of time, because of factors like changed
subsurface conditions; new or modified codes, standards, or
regulations; or new techniques or tools. If you are the least bit uncertain
about the continued reliability of this report, contact your geotechnical
engineer before applying the recommendations in it. A minor amount
of additional testing or analysis after the passage of time – if any is
required at all – could prevent major problems.
Read this Report in Full
Costly problems have occurred because those relying on a geotechnical-
engineering report did not read the report in its entirety. Do not rely on
an executive summary. Do not read selective elements only. Read and refer to the report in full.
You Need to Inform Your Geotechnical Engineer About Change
Your geotechnical engineer considered unique, project-specific factors
when developing the scope of study behind this report and developing
the confirmation-dependent recommendations the report conveys.
Typical changes that could erode the reliability of this report include
those that affect:
• the site’s size or shape;
• the elevation, configuration, location, orientation,
function or weight of the proposed structure and
the desired performance criteria;
• the composition of the design team; or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
or site changes – even minor ones – and request an assessment of their
impact. The geotechnical engineer who prepared this report cannot accept
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered.
Most of the “Findings” Related in This Report Are Professional Opinions
Before construction begins, geotechnical engineers explore a site’s
subsurface using various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing is performed. The data derived from
that sampling and testing were reviewed by your geotechnical engineer,
who then applied professional judgement to form opinions about
subsurface conditions throughout the site. Actual sitewide-subsurface
conditions may differ – maybe significantly – from those indicated in
this report. Confront that risk by retaining your geotechnical engineer
to serve on the design team through project completion to obtain
informed guidance quickly, whenever needed.
This Report’s Recommendations Are Confirmation-Dependent
The recommendations included in this report – including any options or
alternatives – are confirmation-dependent. In other words, they are not
final, because the geotechnical engineer who developed them relied heavily
on judgement and opinion to do so. Your geotechnical engineer can finalize
the recommendations only after observing actual subsurface conditions
exposed during construction. If through observation your geotechnical
engineer confirms that the conditions assumed to exist actually do exist,
the recommendations can be relied upon, assuming no other changes have
occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation.
This Report Could Be Misinterpreted
Other design professionals’ misinterpretation of geotechnical-
engineering reports has resulted in costly problems. Confront that risk
by having your geotechnical engineer serve as a continuing member of
the design team, to:
• confer with other design-team members;
• help develop specifications;
• review pertinent elements of other design professionals’ plans and
specifications; and
• be available whenever geotechnical-engineering guidance is needed.
You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction-phase observations.
Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note
conspicuously that you’ve included the material for information purposes only. To avoid misunderstanding, you may also want to note that
“informational purposes” means constructors have no right to rely on
the interpretations, opinions, conclusions, or recommendations in the
report. Be certain that constructors know they may learn about specific
project requirements, including options selected from the report, only
from the design drawings and specifications. Remind constructors
that they may perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in
a position to give constructors the information available to you, while
requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions. Conducting prebid and
preconstruction conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. This happens in part because soil and rock on
project sites are typically heterogeneous and not manufactured materials
with well-defined engineering properties like steel and concrete. That
lack of understanding has nurtured unrealistic expectations that have
resulted in disappointments, delays, cost overruns, claims, and disputes.
To confront that risk, geotechnical engineers commonly include
explanatory provisions in their reports. Sometimes labeled “limitations,”
many of these provisions indicate where geotechnical engineers’
responsibilities begin and end, to help others recognize their own
responsibilities and risks. Read these provisions closely. Ask questions.
Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
environmental study – e.g., a “phase-one” or “phase-two” environmental
site assessment – differ significantly from those used to perform a
geotechnical-engineering study. For that reason, a geotechnical-engineering
report does not usually provide environmental findings, conclusions, or
recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not
obtained your own environmental information about the project site,
ask your geotechnical consultant for a recommendation on how to find
environmental risk-management guidance.
Obtain Professional Assistance to Deal with Moisture Infiltration and Mold
While your geotechnical engineer may have addressed groundwater,
water infiltration, or similar issues in this report, the engineer’s
services were not designed, conducted, or intended to prevent
migration of moisture – including water vapor – from the soil
through building slabs and walls and into the building interior, where
it can cause mold growth and material-performance deficiencies.
Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by
including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists.
Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of
GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation.
Telephone: 301/565-2733
e-mail: info@geoprofessional.org www.geoprofessional.org
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
February 21, 2024
ES-9583
Lake Samish, LLC
7710 – 203rd Street Southeast
Snohomish, Washington 98296
Attention: Dan Peck
Dear Dan:
Earth Solutions NW, LLC (ESNW) is pleased to present this report titled “Geotechnical
Engineering Study, Proposed Bales Place Short Plat, 11806 – Southeast 192nd Street, Renton,
Washington”. Based on the results of the study, the proposed project is feasible from a
geotechnical standpoint. The study indicates the site is underlain primarily by near-surface fill
and competent glacial till. Light to moderate groundwater seepage was exposed at all test pit
locations during the January 2024 exploration.
We understand the site will be graded to create an access driveway and building pads. New
structural fill should be placed on competent native soil. Areas of existing fill will need to be
removed or reworked to establish suitable bearing conditions in proposed structural areas, as
recommended by ESNW at the time of construction. If earthwork activities occur during wet
weather, additional drainage measures, cement treatment of native soil, and the use of select fill
material will likely be necessary. After completing earthwork activities in accordance with
recommendations in this report, the proposed structures can be supported on conventional
spread and continuous foundations bearing on undisturbed, competent native soil, compacted
native soil, or new structural fill. If structural building pads are disturbed during wet weather,
remediation measures such as cement treatment or overexcavation and replacement with rock
may be necessary in some areas.
In our opinion, the native glacial till deposits should be considered unsuitable for infiltration
purposes from a geotechnical standpoint, given the appreciable fines contents and dense in-situ
condition. Further discussion of infiltration feasibility is provided within this report.
Pertinent geotechnical recommendations are provided in this study. We appreciate the
opportunity to be of service to you on this project. If you have any questions regarding the content
of this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
John M. Neer, G.I.T.
Staff Geologist
15365 NE 90th Street, Suite 100 • Redmond, WA 98052 •(425) 449-4704
3130 Varney Lane, Suite 105 •Pasco, WA 99301 •(509) 905-0275
esnw.com
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Earth Solutions NW, LLC
Table of Contents
ES-9583
PAGE
INTRODUCTION ................................................................................. 1
General .................................................................................... 1
Project Description ................................................................. 1
SITE CONDITIONS ............................................................................. 2
Surface ..................................................................................... 2
Subsurface .............................................................................. 2
Topsoil and Fill ............................................................. 2
Native Soil ..................................................................... 3
Geologic Setting ........................................................... 3
Groundwater ................................................................. 3
Geologically Hazardous Areas Assessment ........................ 3
DISCUSSION AND RECOMMENDATIONS ....................................... 4
General .................................................................................... 4
Site Preparation and Earthwork ............................................. 4
Temporary Erosion Control ......................................... 5
Stripping ....................................................................... 5
Topsoil and Organic Material Removal and
Replacement ................................................................. 6
In-situ and Imported Soils ........................................... 6
Structural Fill ................................................................ 7
Wet-Season Grading .................................................... 7
Excavations and Slopes .............................................. 8
Foundations ............................................................................ 8
Seismic Design ....................................................................... 9
Liquefaction .................................................................. 9
Slab-on-Grade Floors ............................................................. 10
Retaining Walls ....................................................................... 10
Drainage................................................................................... 11
Infiltration Evaluation ................................................... 11
Utility Support and Trench Backfill ....................................... 11
Preliminary Pavement Sections ............................................. 12
LIMITATIONS ...................................................................................... 13
Additional Services ................................................................. 13
REFERENCES .................................................................................... 13
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Earth Solutions NW, LLC
Table of Contents
Cont’d
ES-9583
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Test Pit Location Plan
Plate 3 Retaining Wall Drainage Detail
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration Logs
Appendix B Laboratory Test Results
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Earth Solutions NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED BALES PLACE SHORT PLAT
11806 SOUTHEAST 192ND STREET
RENTON, WASHINGTON
ES-9583
INTRODUCTION
General
This geotechnical engineering study was prepared for the proposed residential development to
be constructed at 11806 – Southeast 192nd Street in Renton, Washington. To complete this
study, we performed the following:
Subsurface exploration to characterize soil and groundwater conditions.
Laboratory testing of soil samples collected at the test pit locations.
Engineering analyses.
Preparation of this report.
Project Description
Based on our understanding of project objectives, the site will be redeveloped with several new
single-family residential lots and associated improvements. Access to the plat will be provided
by Southeast 192nd Street.
Grading plans were not available at the time this report was prepared; however, we anticipate
grading activities will include cuts and fills of up to about four feet to establish building pad and
roadway alignments.
Based on our experience with similar projects, the proposed residential structures will likely be
two to three stories in height and constructed utilizing relatively lightly loaded wood framing
supported on conventional foundations. We anticipate perimeter footing loads of 1 to 2 kips per
linear foot, isolated footing loads of less than 20 kips, and slab-on-grade loading of 150 pounds
per square foot (psf).
If the above design assumptions are incorrect or change, ESNW should be contacted to review
the recommendations in this report. ESNW should review the final design to verify the
geotechnical recommendations provided in this report have been incorporated into the plans.
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SITE CONDITIONS
Surface
The subject site is located at 11806 Southeast 192nd Street in Renton, Washington, as illustrated
on the Vicinity Map (Plate 1). The site consists of one residential tax parcel (King County parcel
number 6198400360) totaling approximately 2.25 acres of land. The site is currently developed
with a single-family residence, a cell tower and service building, and associated improvements.
The site vegetation primarily consists of grass landscaping areas with sporadic trees along the
perimeter. The site topography gently descends from north-northwest to south-southeast with
approximately six feet of elevation change occurring within property boundaries.
Subsurface
An ESNW representative observed, logged, and sampled five test pits on January 26, 2024. The
test pits were excavated within accessible portions of the property using a trackhoe and operator
provided by the client. The test pits were completed to evaluate and classify soil and groundwater
conditions within the proposed development area. The maximum exploration depth was
approximately nine feet below the existing ground surface (bgs), and all explorations were
terminated in undisturbed native soil. The approximate locations of the test pits are depicted on
Plate 2 (Test Pit Location Plan). Please refer to the test pit logs provided in Appendix A for a
more detailed description of subsurface conditions. Representative soil samples collected at the
test pit locations were evaluated in general accordance with Unified Soil Classification System
(USCS) and United States Department of Agriculture (USDA) methods and procedures.
Topsoil and Fill
Topsoil was observed within the upper 4 to 6 inches of existing grades at two test pit locations
(TP-1 and TP-3). The topsoil was characterized by its dark brown color, the presence of fine
organic material, and small root intrusions.
We encountered fill at all test pit locations extending between the existing ground surface and
two feet bgs. The fill was generally characterized as silty sand with and without gravel (USCS:
SM) in a moist to wet condition. The relative density of the fill was generally loose. Minor amounts
of plastic debris were observed within the fill at one test pit location (TP-1).
Underlying the fill, relic topsoil horizons were encountered beginning at depths of roughly 1.5 to
2.0 feet bgs and were on the order of 12 to 18 inches in thickness. The relic topsoil was
characterized by its dark brown color, the presence of fine organic material, and small root
intrusions.
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Native Soil
Underlying the topsoil and fill, native soil consisting primarily of silty sand (USCS: SM) was
encountered, and characterized primarily as glacial till deposits. Native soil relative density
generally increased with depth and became dense and weakly cemented beginning at depths of
roughly two-and-one-half feet to three-and-one-half feet bgs. The native soil was generally
encountered in a moist to wet condition.
Geologic Setting
The referenced geologic map identifies ground moraine deposits (Qgt), otherwise known as
glacial till, across the subject site. As described on the geologic map, ground moraine deposits
are characterized as ablation till over thick sections of lodgment till. Glacial till is typically
comprised of unsorted cobbles, pebbly sand, and sandy silt, with a compact layer (referred to as
“hardpan”) at depth.
The referenced Web Soil Survey (WSS) identifies Alderwood gravelly sandy loam (Map Unit:
AgB) as the primary soil unit underlying the site and surrounding areas. The Alderwood series
was formed in ridges and hills and is derived from glacial drift and/or glacial outwash over dense
glaciomarine deposits.
Based on the subsurface observations, the native soil is generally consistent with glacial till
deposits and Alderwood series soil.
Groundwater
Perched groundwater seepage was observed at all test pit locations during the January 2024
fieldwork. Light to moderate seepage was observed at depths between two to three-and-one-
half feet. Groundwater seepage rates and elevations fluctuate depending on many factors,
including precipitation duration and intensity, the time of year, and soil conditions. Groundwater
seepage flow rates are typically higher during the winter, spring, and early summer months.
Therefore, perched groundwater seepage should be expected in site excavations, particularly if
excavations are made in winter, spring, and early summer months.
Geologically Hazardous Areas Assessment
As part of the geologically hazardous areas assessment, we reviewed the City of Renton (COR)
interactive map and Chapter 4-3 of the Renton Municipal Code (RMC), which focuses on
designations, definitions, and regulations of geologically hazardous areas. RMC 4-3-050
classifies geologically hazardous areas as those areas susceptible to damage relating to
sensitive and protected slopes, landslides, erosion, seismic activity, and coal mines. Based on
our review, the subject site is not mapped within, or adjacent to, any geologically hazardous
areas. Based on the fieldwork performed at the subject site and our site-specific observations, it
is our opinion the site is not within, or adjacent to, any geologically hazardous areas recognized
by the RMC.
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DISCUSSION AND RECOMMENDATIONS
General
Based on the investigation, construction of the proposed residential development is feasible from
a geotechnical standpoint. The primary geotechnical considerations for the proposal are
associated with structural fill placement and compaction, utility trench support and backfill,
drainage, and foundation support.
The site will be graded to create an access driveway and building pads. New structural fill should
be placed on competent native soil. Areas of existing fill will need to be removed or reworked to
establish suitable bearing conditions in proposed structural areas, as recommended by ESNW at
the time of construction. If earthwork activities occur during wet weather, additional drainage
measures, cement treatment of native soil, and the use of select fill material will likely be
necessary. After completing earthwork activities in accordance with recommendations in this
report, the proposed structures can be supported on conventional spread and continuous
foundations bearing on undisturbed, competent native soil, compacted native soil, or new
structural fill. If structural building pads are disturbed during wet weather, remediation measures
such as cement treatment or overexcavation and replacement with rock may be necessary in
some areas.
Site Preparation and Earthwork
Initial site preparation activities will consist of installing temporary erosion control measures,
establishing grading limits, and performing clearing and site stripping. Subsequent earthwork
activities will involve mass site grading and related infrastructure improvements. If earthwork
activities occur during wet weather, additional drainage measures, cement treatment of native
soil (where allowed by the presiding jurisdiction), and the use of select fill material will likely be
necessary during construction.
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Temporary Erosion Control
The following temporary erosion control measures should be considered:
Temporary construction entrances and drive lanes, consisting of at least six inches of
quarry spalls, should be considered to both minimize off-site soil tracking and provide a
stable access entrance surface. Placing geotextile fabric underneath the quarry spalls will
provide greater stability if needed.
Silt fencing should be placed around the site perimeter.
When not in use, soil stockpiles should be covered or otherwise protected to reduce the
potential for soil erosion, especially during periods of wet weather.
Temporary measures for controlling surface water runoff, such as interceptor trenches,
sumps, or interceptor swales, should be installed prior to beginning earthwork activities.
Dry soils disturbed during construction should be wetted to minimize dust and airborne soil
erosion.
When appropriate, permanent planting or hydroseeding will help to stabilize site soils.
Additional TESC BMPs, as specified by the project civil engineer and indicated on the plans
and/or as required by the permitting jurisdiction, should be incorporated into construction
activities. Temporary erosion control measures may be modified during construction as site
conditions require and as recommended by the site erosion control lead.
Stripping
Topsoil was encountered generally within the upper four to six inches of existing grades at two of
the test pit locations. As such, the upper topsoil should be stripped prior to reworking the
underlying existing fill and placing new structural fill.
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Topsoil and Organic Material Removal and Replacement
Relic topsoil layers were observed underlying the fill and ranged in thickness between roughly
one and one-half to two feet. The following is recommended for topsoil and organic material
removal and replacement in structural areas:
Remove upper existing fill soil, segregate from organic and deleterious material, stockpile
and protect from moisture.
Remove topsoil and organic material.
If moderate to heavy groundwater is present following removal, place a layer of quarry
spalls and cover with filter fabric to establish a stable surface.
Begin mass grading with structural fill, utilizing the stockpiled existing fill if deemed
suitable.
In-situ and Imported Soils
Based on the conditions observed during the subsurface exploration, the on-site soil is highly
moisture sensitive. Successful use of the on-site soil as structural fill will largely be dictated by
the moisture content at the time of placement and compaction. Given the limited site area, on-
site remediation efforts (such as aeration) may not be practicable. If the on-site soil cannot be
successfully compacted, the use of an imported soil may be necessary. In our opinion, a
contingency should be provided in the project budget for export of soil that cannot be successfully
compacted as structural fill, particularly if structural backfill take place during periods of extended
rainfall activity. In general, soils with fines contents greater than 5 percent typically degrade
rapidly when exposed to periods of rainfall.
Imported structural fill should consist of a well-graded, granular soil that is capable of achieving
a suitable working moisture content. During wet weather conditions, imported soil intended for
use as structural fill should consist of a well-graded, granular soil with a fines content of 5 percent
or less (where the fines content is defined as the percent passing the Number 200 sieve, based
on the minus three-quarter-inch fraction).
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Structural Fill
Structural fill placed and compacted during site grading activities should meet the following
specifications and guidelines:
Structural fill material Granular soil
Moisture content At or slightly above optimum
Relative compaction (minimum) 95 percent (Modified Proctor)
Loose lift thickness (maximum) 12 inches
The existing soil may not be suitable for use as structural fill unless the material is at (or slightly
above) the optimum moisture content at the time of placement of and compaction. Soil shall not
be placed dry of the optimum moisture content and should be evaluated by ESNW during
construction. A minimum relative compaction of 90 percent may be feasible for certain areas of
mass grading from a geotechnical standpoint but should be evaluated by ESNW at the time of
construction and confirmed with the permitting jurisdiction.
With respect to underground utility installations and backfill, local jurisdictions may dictate the soil
type(s) and compaction requirements. Unsuitable material or debris must be removed from
structural areas, if encountered.
Wet-Season Grading
If earthwork activities occur during wet weather, additional drainage measures, cement treatment
of native soil (if approved by the presiding jurisdiction), and/or the use of select fill material will
likely be necessary. Additionally, measures to protect structural subgrades should be considered
if exposed during wet weather. Site-specific recommendations can be provided at the time of
construction and may include leaving cut areas several inches above design subgrade elevations,
covering working surfaces with crushed rock, protecting structural fill soil from adverse moisture
conditions, and additional TESC recommendations. ESNW can assist in obtaining a wet-season
grading permit if required by the governing jurisdiction.
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Excavations and Slopes
Based on the soil conditions observed at the test pit locations, the following allowable temporary
slope inclinations, as a function of horizontal to vertical (H:V) inclination, may be used. The
applicable Federal Occupation Safety and Health Administration and Washington Industrial
Safety and Health Act soil classifications are also provided:
Areas exposing groundwater seepage 1.5H:1V (Type C)
Loose soil 1.5H:1V (Type C)
Medium dense soil 1H:1V (Type B)
Dense to very dense, cemented native soil 0.75H:1V (Type A)
The presence of groundwater may cause sloughing of temporary slopes. An ESNW
representative should observe temporary and permanent slopes to confirm the slope inclinations
are suitable for the exposed soil conditions and to provide additional excavation and slope
recommendations, as necessary. If the recommended temporary slope inclinations cannot be
achieved, temporary shoring may be necessary to support excavations. Permanent slopes
should be planted with vegetation to enhance stability and to minimize erosion and should
maintain a gradient of 2H:1V or flatter.
Foundations
The proposed residential structures can be supported on conventional spread and continuous
footings bearing on undisturbed, competent native soil, compacted native soil, or new structural
fill. Provided site earthwork activities are completed in accordance with our recommendations,
suitable soil conditions should be exposed in building pad structural subgrade areas. Due to the
high moisture sensitivity of the site soil, foundation subgrade areas should be protected from wet
weather or areas of remediation should be anticipated; a layer of crushed rock can be considered
to protect foundation subgrade areas. If structural building pads are disturbed during wet
weather, remediation measures such as cement treatment or overexcavation and replacement
with rock may be necessary in some areas.
Provided the structures will be supported as described above, the following parameters can be
used for design of the new foundations:
Allowable soil bearing capacity 2,500 psf
Passive earth pressure 300 pcf (equivalent fluid)
Coefficient of friction 0.40
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A one-third increase in the allowable soil bearing capacity may be assumed for short-term wind
and seismic loading conditions. The above passive earth pressure and coefficient of friction
values include a factor-of-safety of 1.5. With structural loading as expected, total settlement in
the range of one inch and differential settlement of about one-half inch is anticipated. Most
settlement should occur during construction when dead loads are applied.
Seismic Design
The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the
Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic
design, specifically with respect to earthquake loads. Based on the soil conditions encountered
at the test pit locations, the parameters and values provided below are recommended for seismic
design per the 2018 IBC.
Parameter Value
Site Class C*
Mapped short period spectral response acceleration, SS (g) 1.365
Mapped 1-second period spectral response acceleration, S1 (g) 0.465
Short period site coefficient, Fa 1.2
Long period site coefficient, Fv 1.5
Adjusted short period spectral response acceleration, SMS (g) 1.638
Adjusted 1-second period spectral response acceleration, SM1 (g) 0.698
Design short period spectral response acceleration, SDS (g) 1.092
Design 1-second period spectral response acceleration, SD1 (g) 0.465
* Assumes very dense native soil conditions, encountered to a maximum depth of nine feet bgs during the January
2024 field exploration, remain very dense to at least 100 feet bgs.
Liquefaction
The referenced liquefaction susceptibility map indicates the subject site maintains very low
liquefaction susceptibility. Liquefaction is a phenomenon where saturated, loose, and
cohesionless sand or silt soil suddenly loses internal strength and behaves as a fluid. This
behavior is in response to increased pore water pressures resulting from an earthquake or
another intense ground shaking. In our opinion, site susceptibility to liquefaction may be
considered negligible. The composition and relatively dense characteristics of the native soil
were the primary bases for this opinion.
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Slab-on-Grade Floors
Slab-on-grade floors for the proposed residential structures should be supported on well-
compacted, firm, and unyielding subgrades. Where feasible, the native soil exposed at the slab-
on-grade subgrade levels can likely be compacted in situ to the specifications of structural fill if
groundwater seepage does not interfere with compaction activities. Unstable or yielding
subgrade areas should be recompacted or overexcavated and replaced with suitable structural
fill prior to slab construction.
A capillary break consisting of at least four inches of free-draining crushed rock or gravel should
be placed below the slabs. The free-draining material should have a fines content of 5 percent
or less (where the fines content is defined as the percent passing the Number 200 sieve, based
on the minus three-quarter-inch fraction). In areas where slab moisture is undesirable, installation
of vapor barriers below the slabs should be considered. If a vapor barrier is to be utilized, it
should be a material specifically intended for use as a vapor barrier and should be installed per
the specifications of the manufacturer.
Retaining Walls
Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The
following parameters may be used for design:
Active earth pressure (unrestrained condition) 35 pcf (equivalent fluid)
At-rest earth pressure (restrained condition) 55 pcf
Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution)*
Passive earth pressure 300 pcf (equivalent fluid)
Coefficient of friction 0.40
Seismic surcharge 8H psf**
* Where applicable.
** Where H equals the retained height (in feet).
The passive earth pressure and coefficient of friction values include a safety factor of 1.5. The
above design parameters are based on a level backfill condition and level grade at the wall toe.
Revised design values will be necessary if sloping grades are to be used above or below retaining
walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other relevant
loads should be included in the retaining wall design.
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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 12 inches of the wall
backfill may consist of a less permeable soil if desired. A perforated drainpipe should be placed
along the base of the wall and connected to an approved discharge location. A typical retaining
wall drainage detail is provided on Plate 3. If drainage is not provided, hydrostatic pressures
should be included in the wall design.
Drainage
Groundwater seepage should be anticipated in site excavations depending on the time of year
grading operations take place, particularly within excavations for utilities. Temporary measures
to control surface water runoff and groundwater during construction would likely involve
interceptor trenches, interceptor swales, and sumps. ESNW should be consulted during
preliminary grading to both identify areas of seepage and provide recommendations to reduce
the potential for seepage-related instability.
Finish grades must be designed to direct surface drain water away from the structures and slopes.
Water must not be allowed to pond adjacent to the structures or slopes. Grades adjacent to the
structures should be sloped away at a gradient of either at least 2 percent for a horizontal distance
of 10 feet or the maximum allowed by adjacent structures. In our opinion, foundation drains
should be installed along building perimeter footings. A typical foundation drain detail is provided
on Plate 4.
Infiltration Evaluation
As indicated in the Subsurface section of this report, the native soil encountered during our
fieldwork was primarily characterized as glacial till and becomes weakly cemented and dense
(hardpan) at depths of about two-and-one-half feet to three-and-one-half feet bgs. A small-scale
Pilot Infiltration Test (PIT) was completed in general accordance with the 2022 City of Renton
Surface Water Design Manual. The PIT was conducted at a depth of six and one-half feet bgs
at test pit location TP-2 in native soil. Following the necessary soaking period, no measurable
infiltration was observed at the test location.
From a geotechnical standpoint, infiltration on the subject site should be considered infeasible
based on the shallow depth to relatively impermeable native soils.
Utility Support and Trench Backfill
The native soil should generally be suitable for utility support. However, remedial measures may
be necessary in some areas to provide support for utilities, such as overexcavation and
replacement with structural fill and/or placement of geotextile fabric. Groundwater may be
encountered within utility excavations, and caving of trench walls may occur where groundwater
is encountered.
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The on-site soil may not be suitable for use as structural backfill throughout utility trench
excavations unless the soil is at (or slightly above) the optimum moisture content at the time of
placement and compaction. If utility installation occurs during the wet season, site soils will likely
be saturated and therefore difficult to use as utility backfill without treatment or aeration. Each
section of the utility lines must be adequately supported in the bedding material. Utility trench
backfill should be placed and compacted to the specifications of structural fill, as previously
detailed in this report, or to the applicable specifications of the presiding jurisdiction.
Preliminary Pavement Sections
The performance of site pavements is largely related to the condition of the underlying subgrade.
To ensure adequate pavement performance, the subgrade should be in a firm and unyielding
condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement
areas should be compacted to the specifications previously detailed in this report. Soft, wet, or
otherwise unsuitable subgrade areas may still exist after base grading activities. Areas
containing unsuitable or yielding subgrade conditions will require remedial measures, such as
overexcavation and replacement with crushed rock or structural fill, prior to pavement.
For lightly loaded pavement areas subjected primarily to passenger vehicles, the following
preliminary pavement sections may be considered:
A minimum of two inches of hot-mix asphalt (HMA) placed over four inches of crushed
rock base (CRB).
A minimum of two inches of HMA placed over three inches of asphalt-treated base (ATB).
For relatively high volume, heavily loaded pavements areas subjected to occasional truck traffic,
the following preliminary pavement sections may be considered:
A minimum of three inches of HMA placed over six inches of CRB.
A minimum of three inches of HMA placed over four and one-half inches of ATB.
A representative of ESNW should be requested to observe subgrade conditions prior to
placement of CRB or ATB. As necessary, supplemental recommendations for achieving
subgrade stability and drainage can be provided. If on-site roads will be constructed with an
inverted crown, additional drainage measures may be recommended to assist in maintaining road
subgrade and pavement stability.
Final pavement design recommendations, including recommendations for heavy traffic areas,
access roads, and frontage improvement areas, can be provided once final traffic loading has
been determined. Road standards utilized by the governing jurisdiction may supersede the
recommendations provided in this report. The HMA, ATB, and CRB materials should conform to
WSDOT specifications. All soil base material should be compacted to a relative compaction of
95 percent, based on the laboratory maximum dry density as determined by ASTM D1557.
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LIMITATIONS
This geotechnical evaluation report has been prepared for the exclusive use of Lake Samish,
LLC and its representatives. 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 observed at the test locations 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.
REFERENCES
The following documents and resources were reviewed as part of the report preparation:
Geologic map of the Renton quadrangle, King County, Washington, prepared by D.R.
Mullineaux, dated 1965
WSS, maintained by the Natural Resources Conservation Service under the USDA
RMC Chapter 4-3-050 – Critical Areas Regulations
2022 City of Renton Surface Water Design Manual, prepared by City of Renton
Liquefaction Susceptibility Map, dated May 2010, prepared by King County
COR Maps (City of Renton GIS database)
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked JMN Date Feb.2024
Date 02/19/2024 Proj.No.9583
Plate 1
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutionsNWLLC
Vicinity Map
Bales Place Short Plat
Renton,Washington
Reference:
King County,Washington
OpenStreetMap.org
NORTH
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.
SITE
Renton
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Drawn MRS
Checked JMN Date Feb.2024
Date 02/19/2024 Proj.No.9583
Plate 2
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutionsNWLLC
Test Pit Location Plan
Bales Place Short Plat
Renton,Washington
NORTH
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.
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.
LEGEND
Approximate Location of
ESNW Test Pit,Proj.No.
ES-9583,Jan.2024
Subject Site
Existing Building
0 50 100 200
Scale in Feet1"=100'
TP-1
TP-1 TP-2
TP-3
TP-4
TP-5
S.E.192ND STREET
116TH AVENUE S.E.
506
500
506
500
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked JMN Date Feb.2024
Date 02/19/2024 Proj.No.9583
Plate 3
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutionsNWLLC
NOTES:
Free-draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No.4 sieve should be
25 to 75 percent.
Sheet Drain may be feasible in lieu
of Free-draining Backfill,per ESNW
recommendations.
Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
LEGEND:
Free-draining Structural Backfill
1-inch Drain Rock
18"Min.
Structural
Fill
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAWING
Retaining Wall Drainage Detail
Bales Place Short Plat
Renton,Washington
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked JMN Date Feb.2024
Date 02/19/2024 Proj.No.9583
Plate 4
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutionsNWLLC
Slope
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
18"Min.
NOTES:
Do NOT tie roof downspouts
to Footing Drain.
Surface Seal to consist of
12"of less permeable,suitable
soil.Slope away from building.
LEGEND:
Surface Seal:native soil or
other low-permeability material.
1-inch Drain Rock
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAWING
Footing Drain Detail
Bales Place Short Plat
Renton,Washington
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Earth Solutions NW, LLC
Appendix A
Subsurface Exploration Logs
ES-9583
The subsurface conditions at the site were explored on January 26, 2024, by excavating five test
pits using a mini-trackhoe and operator provided by the client. The approximate locations of the
test pits are illustrated on Plate 2 of this study. The test pit logs are provided in this Appendix.
The test pits were advanced to a maximum depth of approximately nine feet bgs.
The final logs represent the interpretations of the field logs and the results of laboratory analyses.
The stratification lines on the logs represent the approximate boundaries between soil types. In
actuality, the transitions may be more gradual.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
>
12%
Fines
<
5%
Fines
Highly
Organic
Soils
Silts
and
Clays
Liquid
Limit
50
or
More
Silts
and
Clays
Liquid
Limit
Less
Than
50
Fine-Grained
Soils
-
50%
or
More
Passes
No.
200
Sieve
Coarse-Grained
Soils
-
More
Than
50%
Retained
on
No.
200
Sieve
Sands
-
50%
or
More
of
Coarse
Fraction
Passes
No.
4
Sieve
Gravels
-
More
Than
50%
of
Coarse
Fraction
Retained
on
No.
4
Sieve
>
12%
Fines
<
5%
Fines GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
Well-graded gravel with
or without sand,little to
no fines
Poorly graded gravel with
or without sand,little to
no fines
Silty gravel with or without
sand
Clayey gravel with or
without sand
Well-graded sand with
or without gravel,little to
no fines
Poorly graded sand with
or without gravel,little to
no fines
Silty sand with or without
gravel
Clayey sand with or
without gravel
Silt with or without sand
or gravel;sandy or
gravelly silt
Clay of low to medium
plasticity;lean clay with
or without sand or gravel;
sandy or gravelly lean clay
Organic clay or silt of
low plasticity
Elastic silt with or withoutsandorgravel;sandy or
gravelly elastic silt
Clay of high plasticity;
fat clay with or without
sand or gravel;sandy or
gravelly fat clay
Organic clay or silt of
medium to high plasticity
Peat,muck,and other
highly organic soils
EEaarrtthh SSoolluuttiioonnss NNWWLLC
Geotechnical Engineering,ConstructionObservation/Testing and Environmental Services EXPLORATION LOG KEY
Fill FILL Made Ground
Classifications of soils in this geotechnical report and as shown on the exploration logs are based on visualfieldand/or laboratory observations,which include density/consistency,moisture condition,grain size,andplasticityestimates,and should not be construed to imply field or laboratory testing unless presented herein.
Visual-manual and/or laboratory classification methods of ASTM D2487 and D2488 were used as an
identification guide for the Unified Soil Classification System.
Terms Describing Relative Density and Consistency
Coarse-Grained Soils:
Fine-Grained Soils:
SPT blows/foot
SPT blows/foot
Test Symbols &Units
Fines =Fines Content (%)
MC =Moisture Content (%)
DD =Dry Density (pcf)
Str =Shear Strength (tsf)
PID =Photoionization Detector (ppm)
OC =Organic Content (%)
CEC =Cation Exchange Capacity (meq/100 g)
LL =Liquid Limit (%)
PL =Plastic Limit (%)
PI =Plasticity Index (%)
Component Definitions
Descriptive Term Size Range and Sieve Number
Smaller than No.200 (0.075 mm)
Boulders
Modifier Definitions
Percentage by
Weight (Approx.)
<5
5 to 14
15 to 29
>30_
Modifier
Trace (sand,silt,clay,gravel)
Slightly (sandy,silty,clayey,gravelly)
Sandy,silty,clayey,gravelly
Very (sandy,silty,clayey,gravelly)
Moisture Content
Dry -Absence of moisture,dusty,dry to
the touch
Damp -Perceptible moisture,likely below
optimum MC
Moist -Damp but no visible water,likely
at/near optimum MC
Wet -Water visible but not free draining,
likely above optimum MC
Saturated/Water Bearing -Visible free
water,typically below groundwater table
Symbols
Cement groutsurfaceseal
Bentonite
chips
Grout
seal
Filter pack with
blank casing
section
Screened casing
or Hydrotip with
filter pack
End cap
ATD =At time
of drilling
Static water
level (date)
_>50
Density
Very Loose
Loose
Medium Dense
Dense
Very Dense
Consistency
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
<4
4 to 9
10 to 29
30 to 49
<2
2 to 3
4 to 7
8 to 14
15 to 29
_>30
LLC
EarthSolutionsNWLLC
Cobbles
GravelCoarse GravelFineGravel
Sand
Coarse Sand
Medium Sand
Fine Sand
Silt and Clay
Larger than 12"
3"to 12"
3"to No.4 (4.75 mm)3"to 3/4"3/4"to No.4 (4.75 mm)
No.4 (4.75 mm)to No.200 (0.075 mm)
No.4 (4.75 mm)to No.10 (2.00 mm)
No.10 (2.00 mm)to No.40 (0.425 mm)
No.40 (0.425 mm)to No.200 (0.075 mm)
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
498.5
497.0
495.5
491.0
GB
GB
GB
GB
MC = 18.7
MC = 16.0
MC = 19.9
MC = 18.7
TPSL
SM
TPSL
SM
Dark brown TOPSOIL (Fill)
Brown silty SAND, loose, wet (Fill)
-probed 12"
-plastic debris
Dark brown TOPSOIL with roots
-probed 8"
-moderate groundwater seepage
Gray silty SAND, dense, moist to wet
-mottling to 6.5', weakly cemented
-probed 2"
-becomes very dense
-elevated moisture content due to seepage entering test pit above
Test pit terminated at 8.0 feet below existing grade. Groundwater seepage encountered at3.0 feet during excavation. No caving observed.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was notsurveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for acomplete understanding of subsurface conditions.
0.5
2.0
3.5
8.0
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
PAGE 1 OF 1
TEST PIT NUMBER TP-1
CHECKED BY HTW
NOTES
SURFACE CONDITIONS Grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 1/26/24 COMPLETED 1/26/24
GROUND WATER LEVEL:
GROUND ELEVATION 499 ft
LOGGED BY JMN
LATITUDE 47.43043 LONGITUDE -122.18297
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GE
N
E
R
A
L
B
H
/
T
P
/
W
E
L
L
-
9
5
8
3
.
G
P
J
-
G
I
N
T
U
S
.
G
D
T
-
2
/
2
1
/
2
4
15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.com
Branch Office: Pasco, WA
TESTS
U.
S
.
C
.
S
.
MATERIAL DESCRIPTION
GR
A
P
H
I
C
LO
G
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
497.0
495.5
492.0
GB
GB
GB
MC = 82.5
MC = 12.5
Fines = 34.5
MC = 20.6Fines = 29.3
SM
TPSL
SM
Brown silty SAND, loose, wet (Fill)
-probed 12"
-moderate groundwater seepage at 2'
Dark brown TOPSOIL with roots
-elevated moisture content due to seepage entering test pit above
-probed 2"
Gray silty SAND, dense, moist
-light groundwater seepage
-mottling to 6', weakly cemented[USDA Classification: gravelly sandy LOAM]
-elevated moisture content due to seepage entering test pit above
[USDA Classification: slightly gravelly sandy LOAM]
Test pit terminated at 7.0 feet below existing grade. Groundwater seepage encountered at2.0 and 3.5 feet during excavation. No caving observed.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was notsurveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for acomplete understanding of subsurface conditions.
2.0
3.5
7.0
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
DE
P
T
H
(f
t
)
0.0
2.5
5.0
PAGE 1 OF 1
TEST PIT NUMBER TP-2
CHECKED BY HTW
NOTES
SURFACE CONDITIONS Grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 1/26/24 COMPLETED 1/26/24
GROUND WATER LEVEL:
GROUND ELEVATION 499 ft
LOGGED BY JMN
LATITUDE 47.43042 LONGITUDE -122.18274
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GE
N
E
R
A
L
B
H
/
T
P
/
W
E
L
L
-
9
5
8
3
.
G
P
J
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I
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U
S
.
G
D
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-
2
/
2
1
/
2
4
15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.com
Branch Office: Pasco, WA
TESTS
U.
S
.
C
.
S
.
MATERIAL DESCRIPTION
GR
A
P
H
I
C
LO
G
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
504.5
503.5
502.5
496.5
GB
GB
GB
GB
MC = 44.9
MC = 20.2
Fines = 34.1
MC = 13.9
MC = 15.2
TPSL
SM
TPSL
SM
Dark brown TOPSOIL with roots (Fill)
Brown silty SAND with gravel, loose, wet (Fill)
-probed 12"
Dark brown TOPSOIL
-moderate groundwater seepage at 2.5'
Gray silty SAND, dense, moist to wet
-mottling to 6', weakly cemented
-probed 2"
[USDA Classification: slightly gravelly sandy LOAM]
-elevated moisture content due to seepage entering test pit above
-becomes very dense
Test pit terminated at 8.5 feet below existing grade. Groundwater seepage encountered at
2.5 feet during excavation. No caving observed.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely onthis test log as a standalone document. Refer to the text of the geotechnical report for acomplete understanding of subsurface conditions.
0.5
1.5
2.5
8.5
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
PAGE 1 OF 1
TEST PIT NUMBER TP-3
CHECKED BY HTW
NOTES
SURFACE CONDITIONS Grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 1/26/24 COMPLETED 1/26/24
GROUND WATER LEVEL:
GROUND ELEVATION 505 ft
LOGGED BY JMN
LATITUDE 47.43099 LONGITUDE -122.18355
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GE
N
E
R
A
L
B
H
/
T
P
/
W
E
L
L
-
9
5
8
3
.
G
P
J
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I
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U
S
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G
D
T
-
2
/
2
1
/
2
4
15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.com
Branch Office: Pasco, WA
TESTS
U.
S
.
C
.
S
.
MATERIAL DESCRIPTION
GR
A
P
H
I
C
LO
G
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
502.0
501.0
496.0
GB
GB
MC = 22.4
MC = 13.4
SM
TPSL
SM
Brown silty SAND with gravel, loose, wet (Fill)
-probed 12"
Dark brown TOPSOIL with minor root intrusions
-moderate groundwater seepage at 3'
Gray silty SAND, dense, moist
-mottling, weakly cemented
-probed 3"
-elevated moisture content due to seepage entering test pit above
-mottling ends
-becomes very dense
Test pit terminated at 8.0 feet below existing grade. Groundwater seepage encountered at3.0 feet during excavation. No caving observed.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was notsurveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for acomplete understanding of subsurface conditions.
2.0
3.0
8.0
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
PAGE 1 OF 1
TEST PIT NUMBER TP-4
CHECKED BY HTW
NOTES
SURFACE CONDITIONS Grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 1/26/24 COMPLETED 1/26/24
GROUND WATER LEVEL:
GROUND ELEVATION 504 ft
LOGGED BY JMN
LATITUDE 47.43102 LONGITUDE -122.18294
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GE
N
E
R
A
L
B
H
/
T
P
/
W
E
L
L
-
9
5
8
3
.
G
P
J
-
G
I
N
T
U
S
.
G
D
T
-
2
/
2
1
/
2
4
15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.com
Branch Office: Pasco, WA
TESTS
U.
S
.
C
.
S
.
MATERIAL DESCRIPTION
GR
A
P
H
I
C
LO
G
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
499.0
498.0
492.0
GB
GB
GB
GB
GB
MC = 14.9Fines = 37.3
MC = 49.8
MC = 15.5
MC = 18.1
MC = 16.6
SM
TPSL
SM
Brown silty SAND, loose, moist (Fill)
[USDA Classification: slightly gravelly sandy LOAM]
-probed 14"
Dark brown TOPSOIL
-moderate groundwater seepage at 3'
Gray silty SAND, dense, moist to wet-probed 4"
-mottling to 7', weakly cemented
-becomes very dense
-elevated moisture content due to seepage entering test pit above
Test pit terminated at 9.0 feet below existing grade. Groundwater seepage encountered at
3.0 feet during excavation. No caving observed.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was notsurveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely onthis test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
3.0
9.0
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
PAGE 1 OF 1
TEST PIT NUMBER TP-5
CHECKED BY HTW
NOTES
SURFACE CONDITIONS Grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 1/26/24 COMPLETED 1/26/24
GROUND WATER LEVEL:
GROUND ELEVATION 501 ft
LOGGED BY JMN
LATITUDE 47.43073 LONGITUDE -122.18291
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GE
N
E
R
A
L
B
H
/
T
P
/
W
E
L
L
-
9
5
8
3
.
G
P
J
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G
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/
2
1
/
2
4
15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.com
Branch Office: Pasco, WA
TESTS
U.
S
.
C
.
S
.
MATERIAL DESCRIPTION
GR
A
P
H
I
C
LO
G
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Earth Solutions NW, LLC
Appendix B
Laboratory Test Results
ES-9583
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
LL
TP-02
TP-02
TP-03
TP-05
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
19
19
19
19
%Silt
TP-02
TP-02
TP-03
TP-05
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
4.0ft.
7.0ft.
4.0ft.
1.0ft.
4.00ft.
7.00ft.
4.00ft.
1.00ft.
PL
3
D100
140
Specimen Identification
1
fine
6
HYDROMETER
304
34.5
29.3
34.1
37.3
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Gray Gravelly Sandy Loam. USCS: SM.
USDA: Gray Slightly Gravelly Sandy Loam. USCS: SM.
USDA: Gray Slightly Gravelly Sandy Loam. USCS: SM.
USDA: Brown Slightly Gravelly Sandy Loam. USCS: SM.
6 60
PE
R
C
E
N
T
F
I
N
E
R
B
Y
W
E
I
G
H
T
D10
0.079
0.289
0.382
0.271
0.256
GRAIN SIZE DISTRIBUTION
100
PROJECT NUMBER ES-9583 PROJECT NAME Bales Place Short Plat
GR
A
I
N
S
I
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E
U
S
D
A
E
S
-
9
5
8
3
B
A
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P
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O
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1
3
/
2
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15365 NE 90th Street, Suite 100
Redmond, WA 98052
Office (425) 449-4704 | esnw.comBranch Office: Pasco, WA
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Appendix B
Wetland Reconnaissance by Altmann Oliver Associates, LLC dated June 12, 2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
June 12, 2024
AOA-7338 Dan Peck dan.peck@movement.com
SUBJECT: Wetland and Stream Reconnaissance for 11806 SE 192nd Street Parcel 619840-0360, City of Renton, WA
Dear Dan: On June 6, 2024 I conducted a wetland and stream reconnaissance on the subject property utilizing the methodology outlined in the May 2010 Regional Supplement to
the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys,
and Coast Region (Version 2.0). No wetlands or streams were identified on or adjacent to the property during this field investigation and no wetlands or streams are depicted on the City’s GIS mapping in the vicinity of the site.
The southwest portion of the site is currently developed with a single-family residence and the northeast corner is developed with cell tower and associated infrastructure. The remainder of the site consists primarily of a relatively flat mowed yard with garden areas and patches of black cottonwood (Populus balsamifera) trees
and dense Himalayan blackberry (Rubus armeniacus). No definitive hydrophytic plant communities were identified in the site. Borings taken throughout the site revealed higher chroma non-hydric soils and there was no evidence of ponding or prolonged soil saturation anywhere in the vicinity of
the property during the June 6, 2024 site review. Conclusion No wetlands or streams were identified on or immediately adjacent to the site. This
determination is based on a field investigation conducted on June 6, 2024 during which no hydrophytic plant communities, hydric soils, or evidence of wetland hydrology or natural channels were observed.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Dan Peck June 12, 2024 Page 2 of 2 If you have any questions regarding the reconnaissance, please give me a call.
Sincerely,
ALTMANN OLIVER ASSOCIATES, LLC
John Altmann
Ecologist Attachments
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
2,257 188
Map Title
Legend
128064 Feet
Notes
128
WGS_1984_Web_Mercator_Auxiliary_Sphere
All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The
burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the
user.
City and County Labels
Addresses
Parcels
City and County Boundary
Renton
<all other values>
Environment Designations
Natural
Shoreline High Intensity
Shoreline Isolated High Intensity
Shoreline Residential
Urban Conservancy
Jurisdictions
Streams (Classified)
S - Shoreline
F - Fish
Np - Non-Fish
Ns - Non-Fish Seasonal
Unclassfied
Wetlands
Streets
Points of Interest
Parks
Waterbodies
2021.sid
Red: Band_1
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
King County, EagleView Technologies, Inc.
King County iMap
Date: 6/12/2024 Notes:
The information included on this map has been compiled by King County staff from a variety of sources and is subject to changewithout notice. King County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness,or rights to the use of such information. This document is not intended for use as a survey product. King County shall not be liablefor any general, special, indirect, incidental, or consequential damages including, but not limited to, lost revenues or lost profitsresulting from the use or misuse of the information contained on this map. Any sale of this map or information on this map isprohibited except by written permission of King County.±
~DP 2
~DP 1
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0
WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region
VEGETATION – Use scientific names of plants
Tree Stratum (Plot size: 10'R) Absolute % Cover Dominant Species? Indicator Status Dominance Test Worksheet:
1. Populus balsamifera 90 yes FAC Number of Dominant Species That Are OBL, FACW, or FAC: (A) 2.
3. Total Number of Dominant Species Across All Strata: (B) 4.
50% = , 20% = = Total Cover Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Sapling/Shrub Stratum (Plot size: )
1. Prevalence Index worksheet:
2. Total % Cover of: Multiply by:
3. OBL species x1 =
4. FACW species x2 =
5. FAC species x3 =
50% = , 20% = = Total Cover FACU species x4 =
Herb Stratum (Plot size: 10'R) UPL species x5 =
1. Unidentified mowed grass 95 yes Column Totals: (A) (B)
2. Ranuncules repens 5 no FAC Prevalence Index = B/A =
3. Hydrophytic Vegetation Indicators:
4. 1 – Rapid Test for Hydrophytic Vegetation
5. 2 - Dominance Test is >50%
6. 3 - Prevalence Index is <3.01
7. 4 - Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) 8.
9. 5 - Wetland Non-Vascular Plants1
10. Problematic Hydrophytic Vegetation1 (Explain)
11. 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. 50% = , 20% = = Total Cover
Woody Vine Stratum (Plot size: )
1.
Hydrophytic
Vegetation
Present?
Yes No 2.
50% = , 20% = = Total Cover
% Bare Ground in Herb Stratum
Remarks:
Project Site: Parcel 619840-0360 City/County: Renton/ Sampling Date: 06/06/24
Applicant/Owner: Peck State: WA Sampling Point: DP 1
Investigator(s): John Altmann Section, Township, Range:
Landform (hillslope, terrace, etc.): Flat Local relief (concave, convex, none): none Slope (%):
Subregion (LRR): A Lat: Long: Datum:
Soil Map Unit Name: NWI classification:
Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.)
Are Vegetation , Soil , or Hydrology , significantly disturbed? Are “Normal Circumstances” present? Yes No
Are Vegetation , Soil , or Hydrology , naturally problematic? (If needed, explain any answers in Remarks.)
SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc.
Hydrophytic Vegetation Present? Yes No Is the Sampled Area within a Wetland? Yes No Hydric Soil Present? Yes No
Wetland Hydrology Present? Yes No
Remarks:
Mowed lawn - determination based primarily on soils and hydrology criteria
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0
SOIL Sampling Point: DP 1
Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.)
Depth Matrix Redox Features
(inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks
0-4 10YR 2/2 GSL
5-16 7.5YR 2.5/2 GSL
1Type: C= Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix
Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3:
Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10)
Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2)
Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12)
Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks)
Depleted Below Dark Surface (A11) Depleted Matrix (F3)
3Indicators of hydrophytic vegetation and wetland hydrology must be present, unless disturbed or problematic.
Thick Dark Surface (A12) Redox Dark Surface (F6)
Sandy Mucky Mineral (S1) Depleted Dark Surface (F7)
Sandy Gleyed Matrix (S4) Redox Depressions (F8)
Restrictive Layer (if present):
Hydric Soils Present? Yes No
Type:
Depth (inches):
Remarks: No redoximorphic features
HYDROLOGY
Wetland Hydrology Indicators:
Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required)
Surface Water (A1) Water-Stained Leaves (B9) Water-Stained Leaves (B9)
High Water Table (A2) (except MLRA 1, 2, 4A, and 4B) (MLRA 1, 2, 4A, and 4B)
Saturation (A3) Salt Crust (B11) Drainage Patterns (B10)
Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2)
Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9)
Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2)
Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3)
Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5)
Surface Soil Cracks (B6) Stunted or Stresses Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A)
Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7)
Sparsely Vegetated Concave Surface (B8)
Field Observations:
Surface Water Present? Yes No Depth (inches): Wetland Hydrology Present?
Yes
No
Water Table Present? Yes No Depth (inches):
Saturation Present? (includes capillary fringe) Yes No Depth (inches):
Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available:
Remarks: Dry
Project Site: Parcel 619840-0360
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0
WETLAND DETERMINATION DATA FORM – Western Mountains, Valleys, and Coast Region
VEGETATION – Use scientific names of plants
Tree Stratum (Plot size: ) Absolute % Cover Dominant Species? Indicator Status Dominance Test Worksheet:
1. Number of Dominant Species That Are OBL, FACW, or FAC: (A) 2.
3. Total Number of Dominant Species Across All Strata: (B) 4.
50% = , 20% = = Total Cover Percent of Dominant Species That Are OBL, FACW, or FAC: (A/B) Sapling/Shrub Stratum (Plot size: )
1. Prevalence Index worksheet:
2. Total % Cover of: Multiply by:
3. OBL species x1 =
4. FACW species x2 =
5. FAC species x3 =
50% = , 20% = = Total Cover FACU species x4 =
Herb Stratum (Plot size: 10'R) UPL species x5 =
1. Unidentified mowed grass 70 yes Column Totals: (A) (B)
2. Trifolium repens 30 yes FAC Prevalence Index = B/A =
3. Hydrophytic Vegetation Indicators:
4. 1 – Rapid Test for Hydrophytic Vegetation
5. 2 - Dominance Test is >50%
6. 3 - Prevalence Index is <3.01
7. 4 - Morphological Adaptations1 (Provide supporting data in Remarks or on a separate sheet) 8.
9. 5 - Wetland Non-Vascular Plants1
10. Problematic Hydrophytic Vegetation1 (Explain)
11. 1Indicators of hydric soil and wetland hydrology must be present, unless disturbed or problematic. 50% = , 20% = = Total Cover
Woody Vine Stratum (Plot size: )
1.
Hydrophytic
Vegetation
Present?
Yes No 2.
50% = , 20% = = Total Cover
% Bare Ground in Herb Stratum
Remarks:
Project Site: Parcel 619840-0360 City/County: Renton/ Sampling Date: 06/06/24
Applicant/Owner: Peck State: WA Sampling Point: DP 2
Investigator(s): John Altmann Section, Township, Range:
Landform (hillslope, terrace, etc.): Flat Local relief (concave, convex, none): none Slope (%):
Subregion (LRR): A Lat: Long: Datum:
Soil Map Unit Name: NWI classification:
Are climatic / hydrologic conditions on the site typical for this time of year? Yes No (If no, explain in Remarks.)
Are Vegetation , Soil , or Hydrology , significantly disturbed? Are “Normal Circumstances” present? Yes No
Are Vegetation , Soil , or Hydrology , naturally problematic? (If needed, explain any answers in Remarks.)
SUMMARY OF FINDINGS – Attach site map showing sampling point locations, transects, important features, etc.
Hydrophytic Vegetation Present? Yes No Is the Sampled Area within a Wetland? Yes No Hydric Soil Present? Yes No
Wetland Hydrology Present? Yes No
Remarks:
Mowed lawn - determination based primarily on soils and hydrology criteria
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
US Army Corps of Engineers Western Mountains, Valleys, and Coast – Version 2.0
SOIL Sampling Point: DP 2
Profile Description: (Describe to the depth needed to document the indicator or confirm the absence of indicators.)
Depth Matrix Redox Features
(inches) Color (moist) % Color (moist) % Type1 Loc2 Texture Remarks
0-16 10YR 3/3 GL
1Type: C= Concentration, D=Depletion, RM=Reduced Matrix, CS=Covered or Coated Sand Grains. 2Location: PL=Pore Lining, M=Matrix
Hydric Soil Indicators: (Applicable to all LRRs, unless otherwise noted.) Indicators for Problematic Hydric Soils3:
Histosol (A1) Sandy Redox (S5) 2 cm Muck (A10)
Histic Epipedon (A2) Stripped Matrix (S6) Red Parent Material (TF2)
Black Histic (A3) Loamy Mucky Mineral (F1) (except MLRA 1) Very Shallow Dark Surface (TF12)
Hydrogen Sulfide (A4) Loamy Gleyed Matrix (F2) Other (Explain in Remarks)
Depleted Below Dark Surface (A11) Depleted Matrix (F3)
3Indicators of hydrophytic vegetation and wetland hydrology must be present, unless disturbed or problematic.
Thick Dark Surface (A12) Redox Dark Surface (F6)
Sandy Mucky Mineral (S1) Depleted Dark Surface (F7)
Sandy Gleyed Matrix (S4) Redox Depressions (F8)
Restrictive Layer (if present):
Hydric Soils Present? Yes No
Type:
Depth (inches):
Remarks: No redoximorphic features
HYDROLOGY
Wetland Hydrology Indicators:
Primary Indicators (minimum of one required; check all that apply) Secondary Indicators (2 or more required)
Surface Water (A1) Water-Stained Leaves (B9) Water-Stained Leaves (B9)
High Water Table (A2) (except MLRA 1, 2, 4A, and 4B) (MLRA 1, 2, 4A, and 4B)
Saturation (A3) Salt Crust (B11) Drainage Patterns (B10)
Water Marks (B1) Aquatic Invertebrates (B13) Dry-Season Water Table (C2)
Sediment Deposits (B2) Hydrogen Sulfide Odor (C1) Saturation Visible on Aerial Imagery (C9)
Drift Deposits (B3) Oxidized Rhizospheres along Living Roots (C3) Geomorphic Position (D2)
Algal Mat or Crust (B4) Presence of Reduced Iron (C4) Shallow Aquitard (D3)
Iron Deposits (B5) Recent Iron Reduction in Tilled Soils (C6) FAC-Neutral Test (D5)
Surface Soil Cracks (B6) Stunted or Stresses Plants (D1) (LRR A) Raised Ant Mounds (D6) (LRR A)
Inundation Visible on Aerial Imagery (B7) Other (Explain in Remarks) Frost-Heave Hummocks (D7)
Sparsely Vegetated Concave Surface (B8)
Field Observations:
Surface Water Present? Yes No Depth (inches): Wetland Hydrology Present?
Yes
No
Water Table Present? Yes No Depth (inches):
Saturation Present? (includes capillary fringe) Yes No Depth (inches):
Describe Recorded Data (stream gauge, monitoring well, aerial photos, previous inspections), if available:
Remarks: Dry
Project Site: Parcel 619840-0360
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Appendix C
Arborist Report by Layton Tree Consulting, LLC dated March 27, 2024, Updated September 3, 2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
LAYTON TREE CONSULTING, LLC
It’s all about trees……
PO BOX 572, SNOHOMISH, WA 98291-0572 * 425-220-5711 * bob@laytontreeconsulting.com
ARBORIST REPORT
TREE RETENTION / PROTECTION PLAN
11806 SE 192nd Street
Renton, WA
Report Prepared by:
Bob Layton
Registered Consulting Arborist #670
Certified Arborist #PN-2714A
March 27, 2024
Updated December 2, 2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 2 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Table of Contents
Assignment.................................................................................................................................................... 3
Description .................................................................................................................................................... 3
Methodology ................................................................................................................................................. 3
Judging Condition...................................................................................................................................... 4
Observations ................................................................................................................................................. 4
Discussion/Recommendations ...................................................................................................................... 5
General Tree Protection Guidelines .............................................................................................................. 6
General Tree Protection Measures ............................................................................................................... 6
Tree Density-Tree Replacement ................................................................................................................... 7
Arborist Disclosure Statement ...................................................................................................................... 8
Attachments
Photos, pages 9 - 21
Tree Summary Tables
Tree Locator/Conditions Map
Tree Plan Map
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 3 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Assignment
Layton Tree Consulting, LLC was asked to compile an Arborist Report for a property in Renton, located at
11806 SE 192nd Street. The purpose of the report is to satisfy City requirements regarding tree retention
regulations associated with the proposed re-development of the property.
My assignment is to prepare a written report on present tree conditions, and to provide appropriate
recommendations for the protection of retained or protected trees during development.
This report covers all of the criteria set forth under the City of Renton’s tree regulations, Municipal Code
Section 4-4-130 - Tree Retention and Land Clearing Regulations. Properties subject to an active land
development permit shall retain a minimum of thirty percent (30%) of all significant trees on site.
Date of Field Examination: March 21, 2024
Description
Most of the property is open and covered in grasses. Trees exist mostly on the property perimeters. 48
trees that meet the size requirements for a significant tree were identified on the property. A significant
tree is any tree with a caliper of at least 6-inches or alder or cottonwood tree at least 8-inches. Trees
certified as high-risk shall not be considered significant.
Trees have been marked with a numbered aluminum tag, attached to the lower trunk. Tree numbers
correspond with the numbers on the attached Tree Summary Tables and map.
An additional 11 off-site trees were also assessed. These are located within a proximity of the east and west
property lines. There are also five trees within the right-of-way of SE 192nd Street.
Methodology
Each tree in this report was visited. Tree diameters were measured by tape. The tree heights were
measured using a Spiegel Relaskop. Each tree was visually examined for defects and vigor. The tree
assessment procedure involves the examination of many factors:
• The crown or canopy of the tree is examined for current vigor/health by examining the foliage for
appropriate color and density, the vegetative buds for color and size, and the branches for structural
form and annual shoot growth; and the overall presence of limb dieback and/or any disease issues.
• The trunk or main stem of the tree is inspected for decay, which includes cavities, wounds, fruiting
bodies of decay (conks or mushrooms), seams, insect pests, bleeding or exudation of sap, callus
development, broken or dead tops, structural defects and unnatural leans. Structural defects can
include but are not limited to excessive or unnatural leans, crooks, forks with V-shaped crotches,
multiple attachments.
• The root collar and exposed surface roots are inspected for the presence of decay, insect damage, as
well as if they have been injured or wounded, undermined or exposed, or the original grade has
been altered.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 4 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Judging Condition
The three condition categories are described as follows:
Good – free of significant structural defects, no disease concerns, minor pest issues, no significant root
issues, good structure/form with uniform crown or canopy, foliage of normal color and density, average or
normal vigor, will be wind firm if isolated or left as part of a grouping or grove of trees, suitable for its
location
Fair – minor to moderate structural defects not expected to contribute to a failure in near future, no disease
concerns, moderate pest issues, no significant root issues, asymmetric or unbalanced crown or canopy,
average or normal vigor, foliage of normal color, moderate foliage density, will be wind firm if left as part of
a grouping or grove of trees, cannot be isolated, suitable for its location
Poor – major structural defects expected to cause fail in near future, disease or significant pest concerns,
decline due to old age, significant root issues, asymmetric or unbalanced crown or canopy, sparse or
abnormally small foliage, poor vigor, not suitable for its location
The attached Tree Summary Table provides specific information on tree sizes and dripline measurements.
Observations
Most of the property is open and covered in grasses. Trees exist mostly on the property perimeters.
Noteworthy observations are discussed as follows.
14 of the subject trees are a grouping of native black cottonwood at the back of the property. Roughly
half of these have developed major leans and are highly susceptible to failure/stem breakage. See
pictures below. Eight are rated as ‘high’ risk.
Several trees were planted around the tower site and adjacent to its access drive on the east perimeter
of the property. They appear to have been planted for screening purposes. Species include
predominantly ‘Excelsa’ Western red cedar, a few Sitka spruce and a few Colorado blue spruce. These
are mostly in good condition. A few of the cedars have been damaged by drought stress in the past,
evident by some top decline/dieback. A few of the cedars along the access driveway have sunscald
damage, evident by cambium dieback on the lower trunks – west sides. This likely occurred when brush
was removed around the trees and lower trunks were exposed to the sun.
Some black cottonwood and red alder trees have naturally regenerated within the east perimeter
planting areas. Cottonwood Trees #27, #28 and #29 have overtopped the cedars and spruce are
somewhat suppressing them.
Off-site/Neighboring Trees
Trees #101 and #108 > #111 are located within the SE 192nd street right -of-way. #101 is a young
Western red cedar that was topped several of years ago at roughly 6-feet above ground. The intention
was probably to maintain it as a hedge but was left unmanaged and has developed multiple new tops to
a height of 24-feet. It is in fair condition. Tree #1 adjacent to it is in the same condition.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 5 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Tree #110 is a mature European white birch. It is in poor condition, evident by dead and broken tops. It
is infected with the Bronze Birch Borer pest. It is in an ultimate state of decline. It is not viable.
Tree #111 is a young to semi-mature bigleaf maple in a grouping with property trees #46 and #47 that
are the same size and species. Vigor appears to be good. These are surrounded by a compacted gravel
driveway.
Tree #102 is a young Douglas fir in good condition with no concerning issues.
Tree #103 is a large, mature bigleaf maple. Some decay within the lower trunk and upper bole is visible
from the subject property. Overall condition is rated as ‘fair’.
Tree #104 is a mature native Scouler’s willow located close to the west property line. It appears to be of
good vigor for age. This is a short-lived species. There is moderate deadwood within the canopy.
Tree #105 is a semi-mature bigleaf maple located roughly 12-feet off of the west property line fence. No
concerning issues were observed from the subject property side. Condition is ‘good’.
Discussion/Recommendations
48 trees that meet the size requirements for a significant tree were identified on the property. A significant
tree is any tree with a caliper of at least 6-inches or alder or cottonwood tree at least 8-inches. Trees
certified as high-risk shall not be considered significant. Eight of the subject cottonwood trees are high risk
and therefore considered non-significant. Five of the subject trees are located within the proposed new
public street right-of-way. There are a total of 35 significant trees on the property.
The cottonwood trees are problematic. This is a very fast-growing and vigorous species. The species has
brittle wood structure and is prone to large branch and stem failures. Complete crown failure, and loss
of large lateral limbs is common, especially where the tree is dominant and subject to strong winds, or
wet snow1. Sudden limb drop is common at all times of year, often with no wind or other predisposing
factors in play. These are not good candidates for retention and not suitable within the striking distance
of high value targets. They will be an issue for the new homeowners in the near future. Removal and
replacement are recommended.
The proposal is to retain the trees #3, #7, #23 and #25. These are well-positioned for successful
retention in the corners of the property away from proposed disturbances. See the attached tree plan
map. Position the tree protection barrier/fencing around them as shown on the map. Unfortunately,
there is little opportunity to retain trees at this site. Trees best positioned for successful preservation at
the back of the property are all cottonwoods.
All of the trees within the SE 192nd Street right-of-way and those adjacent to it will need to be removed
for utility upgrades and street frontage improvements.
1 Dunster, J, A. 2003. Preliminary Species Profiles for Tree Failure Assessment. Bowen Island: Dunster & Associates
Environmental Consultants Ltd. Page 27
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 6 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
A realignment of the cell tower property access drive will require the removal of Trees #35 > #39. Since
these trees are within a required easement, they are not included in the tree retention calculations.
General Tree Protection Guidelines
Tree protection fencing shall be positioned around any retained and/or protected trees prior to site
demolition or bringing any heavy equipment onto the site. This will help to define clearing limits and
protect soils and surface roots.
Any roots damaged during site work outside of the tree protection fenced area shall be pruned clean at
sound tissue prior to backfilling or finishing areas. Sound tissue is where the root is undamaged and the
bark is completely intact with the root. This will help roots to seal off potential decay and allow them to
sprout new growth. Any disturbed areas near protected trees shall be watered weekly during the dry
season of June through September. This will help to create a favorable environment for new root
growth and reduce the overall stress associated with root loss and disturbance.
Simply finish the landscape within the driplines by maintaining the existing lawn or covering the ground
with a 3 to 4-layer of organic mulch. Maintain the existing grades inside tree protection areas. Keep
large plantings, irrigation trenching and construction of hardscapes outside of tree protection areas. All
landscape work within the tree protection zone shall be completed by hand-labor only.
General Tree Protection Measures
The following guidelines are recommended to ensure that the designated space set aside for the
retained trees is protected and construction impacts are kept to a minimum. Tree Protection Standards
have been set forth under RMC 4-4-130 H. Performance Standards for Land Development/Building
Permits; 9. Protection Measures During Construction. Review this code section prior to the start of
work.
• Tree protection fencing shall be erected per prior to moving any heavy equipment on site. Doing
this will set clearing limits and avoid compaction of soils within root zones of retained trees.
• Excavation limits shall be laid out in paint on the ground to avoid over excavating.
• To establish sub grade for foundations, curbs and pavement sections near the trees, soil should
be removed parallel to the roots and not at 90-degree angles to avoid breaking and tearing
roots that lead back to the trunk within the drip-line. Any roots damaged during these
excavations should be exposed to sound tissue and cut cleanly with a saw.
• Areas excavated within the drip-line of retained trees should be thoroughly irrigated weekly
during dry periods.
• Preparations for final landscaping shall be accomplished by hand within the drip-lines of
retained trees. Large equipment shall be kept outside of the tree protection zones at all times.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 7 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Tree Density-Tree Replacement
H. PERFORMANCE STANDARDS FOR LAND DEVELOPMENT PERMITS:
1. Protected Trees: Trees required to be retained or planted pursuant to this subsection H1 are
considered protected trees, as defined in RMC 4-11-200, Definitions T. Protected trees shall be retained
or planted as follows:
a. Minimum Tree Retention Requirements: Properties subject to an active land development permit
shall retain a minimum of thirty percent (30%) of all significant trees on site.
There are a total of 35 significant trees on the property. Five of these are within the proposed new
public road right-of-way, requiring the retention of 9 trees. The proposal is to retain 4 of the 30 existing
significant trees on the property, which equates to 13.3%.
b. Tree Credit Requirements: With the exception of interior remodels not involving any building
addition, removal of trees, or alteration of impervious areas, properties subject to an active land
development permit shall comply with all of the following minimum tree credit requirements, and apply
the tree credit value table in subsection H1bv of this Section:
i. Tree credit requirements shall apply at a minimum rate of thirty (30) credits per net acre.
ii. Either tree retention or a combination of tree retention and supplemental tree planting (with new
small, medium, or large tree species) shall be provided to meet or exceed the minimum tree credits
required for the site.
Because the proposal falls short of 30% retention of significant trees, many replacement tree credits will
be required. The landscape architect will determine the number of small, medium and large
replacement trees needed to satisfy city codes and to develop an appropriate tree replacement plan for
the project.
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 8 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Arborist Disclosure Statement
Arborists are tree specialists who use their education, knowledge, training and experience to examine
and assess trees, recommend measures to enhance the beauty and health of trees, and attempt to
reduce the risks associated with living near trees. Clients may choose to accept or disregard the
recommendations of the arborist, or to seek additional advice.
Arborists cannot detect every condition that could possibly lead to the structural failure of a tree. Trees
are living organisms that grow, respond to their environment, mature, decline and sometimes fail in
ways we do not fully understand. Conditions are often hidden within trees and below ground.
Arborists cannot guarantee that a tree will be healthy and/or safe under all circumstances, or for a
specified period of time. Likewise, remedial treatments, like any medicine, cannot be guaranteed.
Treatment, pruning and removal of trees may involve considerations beyond the scope of the arborist’s
services such as property boundaries, property ownership, site lines, disputes between neighbors, and
other issues. Arborists cannot take such considerations into account unless complete and accurate
information is disclosed to the arborist. An arborist should then be expected to reasonably rely upon
the completeness and accuracy of the information provided.
Trees can be managed, but they cannot be controlled. To live near trees is to accept some degree of
risk. The only way to eliminate all risk associated with trees is to eliminate all trees
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 9 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Photo Documentation
Looking west down right-of-way, Trees #1 and #101 in background, Trees #46, #47 and #111 in
foreground
Trees #2, #3 and #4 in southwest corner of property
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 10 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Tree #2
Trees #3 and #4
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 11 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Tree #3 on left, off-site Tree #102 on right
Off-site Tree #103
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 12 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Tree #7 in back northwest corner, Neighboring trees #104 and #105 on left
Looking west to NW corner – Tree #7, #105 in background
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 13 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Looking east down north perimeter to large cottonwood grouping, Trees #8 > #22
Base of Tree #9, weak forked trunk union
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 14 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Cottonwood grouping, trees have developed major problematic leans
Upper crowns of trees pictured above
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 15 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Looking east down north perimeter to Trees #22 > #34
Trees #23 > #30
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 16 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Looking to NE corner, Tree #25 center, #106 on right opposite fence
Tree #30
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 17 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Trees #31 > #34
Looking to outer NE corner, Tree #35 center, #36 on right, #107 left opposite fence
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 18 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Trees #35 > #39 on east perimeter
Tree #39 in foreground
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 19 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Looking north down east perimeter, Tree #44 on right, large cottonwood tree farther east
ROW Tree #110
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 20 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
ROW Trees #108 and #109
Looking west to Trees #45 and #108
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Initial Arborist Report – 11806 SE 192nd ST
Page 21 Layton Tree Consulting LLC March 27, 2024
Updated December 2, 2024
Trees #46, #47 and #111
Tree #48 in back of existing house
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Layton Tree Consulting LLC
For:Lake Samish LLC
Site:11806 SE 192nd ST - Renton
Tree Summary Table
Date:
DBH/Est.Save Significant
Tree/Caliper Height Tree Risk Tree
Tag #Species (inches)(feet)Credit Condition Rating Yes/No Comments Proposal
N S E W
1 Western red cedar 8,5 (9)30 8 10 6 8 Fair Low Yes topped, multiple tops Remove
2 Western red cedar 31 62 14 14 16 16 Good Low Yes good form and vigor Remove
3 Norway spruce 15 45 7 12 14 12 14 Good Low Yes good form and vigor Save
4 English holly 7 20 NA NA NA NA Fair Low Yes typical, forked trunk Remove
5 black cottonwood 16 80 NA NA NA NA Fair Moderate Yes poor stem taper Remove
6 black cottonwood 14 80 NA NA NA NA Fair Moderate Yes poor stem taper Remove
7 bigleaf maple 16 66 7 16 16 16 14 Good Low Yes good form and vigor Save
8 black cottonwood 16 70 NA NA NA NA Fair Moderate Yes poor stem taper Remove
9 black cottonwood 14,11 (17)60 NA NA NA NA Poor High No double trunk, weak forked stem union Remove
10 black cottonwood 10 70 NA NA NA NA Poor High No heavy lean Remove
11 black cottonwood 11 60 NA NA NA NA Fair Moderate Yes lean,poor stem taper Remove
12 black cottonwood 12 65 NA NA NA NA Fair Moderate Yes poor stem taper Remove
13 black cottonwood 13 60 NA NA NA NA Poor High No heavy lean Remove
14 black cottonwood 34 130 NA NA NA NA Fair Moderate Yes mature Remove
15 black cottonwood 15 80 NA NA NA NA Poor High No heavy lean Remove
16 black cottonwood 22 95 NA NA NA NA Fair Moderate Yes crook,lean Remove
17 black cottonwood 21 100 NA NA NA NA Fair Moderate Yes moderate lean Remove
18 black cottonwood 18 110 NA NA NA NA Poor High No heavy lean Remove
19 black cottonwood 24 110 NA NA NA NA Poor High No heavy lean Remove
20 black cottonwood 8 40 NA NA NA NA Poor High No heavy lean Remove
21 black cottonwood 10,8 (13)40 NA NA NA NA Poor High No heavy lean Remove
22 black cottonwood 24 90 NA NA NA NA Fair Moderate Yes typical Remove
23 Norway spruce 13 40 6 14 8 8 12 Good Low Yes good form and vigor Save
24 black cottonwood 15 90 NA NA NA NA Fair Moderate Yes significant lean north Remove
25 Western red cedar 12 45 5 8 10 8 8 Good Low Yes good form, decent vigor Save
26 Western red cedar 11 40 8 8 8 10 Fair Low Yes foliage somewhat sparse Remove
27 black cottonwood 18 95 NA NA NA NA Fair Moderate Yes typical, suppressing cedars Remove
28 black cottonwood 17 90 NA NA NA NA Fair Moderate Yes typical, suppressing cedars Remove
29 black cottonwood 17 95 NA NA NA NA Fair Moderate Yes typical, suppressing cedars Remove
30 Western red cedar 14,12 (18)40 12 10 12 12 Fair Low Yes some top decline Remove
31 Western red cedar 15 40 12 10 12 12 Good Low Yes good form and vigor Remove
32 Sitka spruce 13 45 14 10 14 10 Good Low Yes natural lean NE,good vigor Remove
33 Western red cedar 12,9 (15)40 8 10 8 10 Fair Low Yes some top decline Remove
Drip-Line
(feet)
3/21/2024
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Layton Tree Consulting LLC
For:Lake Samish LLC
Site:11806 SE 192nd ST - Renton
Tree Summary Table
Date:
DBH/Est.Save Significant
Tree/Caliper Height Tree Risk Tree
Tag #Species (inches)(feet)Credit Condition Rating Yes/No Comments Proposal
N S E W
Drip-Line
(feet)
3/21/2024
34 Western red cedar 11,9,8 (16)40 12 12 10 8 Good Low Yes good form and vigor Remove
40 Western red cedar 17 30 12 12 10 10 Good Low Yes good form and vigor Remove
41 Colorado blue spruce 17 35 14 14 12 12 Good Low Yes good form and vigor Remove
42 Western red cedar 10,9 (13)30 10 10 10 8 Fair Low Yes trunk decay, past sunscald damage Remove
43 Western red cedar 12 25 8 8 6 6 Fair Low Yes trunk decay, past sunscald damage Remove
44 Western red cedar 11 22 10 10 8 8 Good Low Yes good form and vigor Remove
45 Sitka spruce 21 44 16 26 14 14 Good Low Yes good form and vigor Remove
46 bigleaf maple 12 46 6 6 6 10 Fair Low Yes surrounded by compacted gravel Remove
47 bigleaf maple 12 50 10 6 12 8 Fair Low Yes surrounded by compacted gravel Remove
48 Norway maple 11 40 12 16 12 12 Good Low Yes no concerns Remove
25
Within Cell Tower Access Easement
35 Western red cedar 16 36 8 10 10 12 Good Low Yes good form and vigor Remove
36 Colorado blue spruce 9 26 6 8 8 6 Good Low Yes good form and vigor Remove
37 red alder 11 20 NA NA NA NA Poor Moderate Yes broken, major lean Remove
38 Western red cedar 10,8 (13)35 8 10 8 10 Fair Low Yes significant trunk decay,decent vigor, low risk Remove
39 red alder 8 40 NA NA NA NA Fair Moderate Yes natural lean west Remove
Neighboring/Off-site Trees
101 Western red cedar 6,5,4 (9)24 NA 4 6 6 6 Fair Low Yes topped, multiple tops Remove
102 Douglas fir 8 40 NA 10 12 10 NA Good Low Yes young specimen Protect
103 bigleaf maple 30 85 NA 20 22 26 NA Fair Moderate Yes moderate trunk decay,upper bole Protect
104 Scoulers willow 24,16 (29)55 NA 12 20 16 NA Fair Moderate Yes moderate trunk decay Protect
105 bigleaf maple 26 70 NA 16 20 20 NA Good Low Yes good form and vigor Protect
106 Sitka spruce 15 50 NA 14 14 NA 10 Good Low Yes adelgids,moderate infection , forked top Protect
107 Sitka spruce 11 25 NA NA 8 6 12 Fair Low Yes suppressed, natural lean west Protect
108 Western red cedar 14 30 NA 10 12 10 10 Good Low Yes good form and vigor Remove
109 red alder 10 45 NA 8 12 8 8 Fair Moderate Yes typical, decent vigor Remove
110 white birch 16 25 NA NA NA NA NA Poor Moderate No dead,broken tops Remove
111 bigleaf maple 14 50 NA 6 14 10 14 Fair Low Yes surrounded by compacted gravel Remove
Dripline measurements from face of trunk
Calculated DBH/Caliper: the DBH is parenthesis is the square root of the sum of the dbh for each individual stem
squared (example with 3 stems: dbh = square root [(stem1)2 +(stem2)2 +(stem3)2 ]).
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Appendix D
WWHM Output
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
WWHM2012
PROJECT REPORT
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:15 AM Page 2
General Model Information
Project Name:Peck WWHM (2024-11-04)
Site Name:Bales Place Short Plat
Site Address:11806 SE 192nd Street
City:Renton
Report Date:12/5/2024
Gage:Seatac
Data Start:1948/10/01
Data End:2009/09/30
Timestep:15 Minute
Precip Scale:1.000
Version Date:2019/09/13
Version:4.2.17
POC Thresholds
Low Flow Threshold for POC1:50 Percent of the 2 Year
High Flow Threshold for POC1:50 Year
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:15 AM Page 3
Landuse Basin Data
Predeveloped Land Use
Basin 1
Bypass:No
GroundWater:No
Pervious Land Use acre
C, Forest, Flat 2.24
Pervious Total 2.24
Impervious Land Use acre
Impervious Total 0
Basin Total 2.24
Element Flows To:
Surface Interflow Groundwater
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:15 AM Page 4
Mitigated Land Use
Basin 1
Bypass:No
GroundWater:No
Pervious Land Use acre
C, Lawn, Flat 0.98
Pervious Total 0.98
Impervious Land Use acre
ROADS FLAT 0.39
ROOF TOPS FLAT 0.73
SIDEWALKS FLAT 0.14
Impervious Total 1.26
Basin Total 2.24
Element Flows To:
Surface Interflow Groundwater
Contech CMP 1 Contech CMP 1
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:15 AM Page 7
Analysis Results
POC 1
+ Predeveloped x Mitigated
Predeveloped Landuse Totals for POC #1
Total Pervious Area:2.24
Total Impervious Area:0
Mitigated Landuse Totals for POC #1
Total Pervious Area:0.98
Total Impervious Area:1.26
Flow Frequency Method:Log Pearson Type III 17B
Flow Frequency Return Periods for Predeveloped. POC #1
Return Period Flow(cfs)
2 year 0.065858
5 year 0.103432
10 year 0.124726
25 year 0.147286
50 year 0.161245
100 year 0.173119
Flow Frequency Return Periods for Mitigated. POC #1
Return Period Flow(cfs)
2 year 0.037401
5 year 0.05643
10 year 0.072206
25 year 0.096281
50 year 0.117579
100 year 0.142083
Annual Peaks
Annual Peaks for Predeveloped and Mitigated. POC #1
Year Predeveloped Mitigated
1949 0.065 0.028
1950 0.081 0.034
1951 0.145 0.096
1952 0.046 0.026
1953 0.037 0.031
1954 0.057 0.031
1955 0.091 0.031
1956 0.072 0.046
1957 0.058 0.031
1958 0.065 0.033
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:53 AM Page 8
1959 0.056 0.028
1960 0.098 0.072
1961 0.055 0.036
1962 0.034 0.026
1963 0.047 0.032
1964 0.062 0.033
1965 0.045 0.045
1966 0.043 0.030
1967 0.090 0.033
1968 0.056 0.030
1969 0.055 0.030
1970 0.045 0.032
1971 0.048 0.032
1972 0.108 0.074
1973 0.049 0.044
1974 0.053 0.033
1975 0.072 0.030
1976 0.052 0.032
1977 0.006 0.026
1978 0.046 0.034
1979 0.028 0.024
1980 0.102 0.092
1981 0.041 0.031
1982 0.079 0.046
1983 0.071 0.033
1984 0.044 0.027
1985 0.026 0.028
1986 0.114 0.038
1987 0.101 0.054
1988 0.040 0.028
1989 0.026 0.027
1990 0.211 0.075
1991 0.127 0.062
1992 0.049 0.035
1993 0.051 0.027
1994 0.017 0.024
1995 0.073 0.037
1996 0.154 0.104
1997 0.129 0.129
1998 0.029 0.027
1999 0.121 0.071
2000 0.051 0.033
2001 0.009 0.023
2002 0.056 0.043
2003 0.071 0.030
2004 0.092 0.083
2005 0.066 0.032
2006 0.078 0.045
2007 0.157 0.151
2008 0.202 0.097
2009 0.099 0.040
Ranked Annual Peaks
Ranked Annual Peaks for Predeveloped and Mitigated. POC #1
Rank Predeveloped Mitigated
1 0.2111 0.1509
2 0.2021 0.1291
3 0.1567 0.1037
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:53 AM Page 9
4 0.1543 0.0974
5 0.1450 0.0961
6 0.1290 0.0924
7 0.1271 0.0834
8 0.1210 0.0747
9 0.1142 0.0739
10 0.1080 0.0718
11 0.1024 0.0705
12 0.1010 0.0622
13 0.0993 0.0537
14 0.0981 0.0455
15 0.0922 0.0455
16 0.0905 0.0453
17 0.0896 0.0445
18 0.0807 0.0444
19 0.0787 0.0434
20 0.0780 0.0399
21 0.0732 0.0382
22 0.0721 0.0366
23 0.0720 0.0363
24 0.0712 0.0355
25 0.0705 0.0339
26 0.0661 0.0338
27 0.0655 0.0330
28 0.0647 0.0328
29 0.0622 0.0327
30 0.0581 0.0326
31 0.0568 0.0326
32 0.0562 0.0325
33 0.0559 0.0324
34 0.0558 0.0318
35 0.0553 0.0318
36 0.0546 0.0316
37 0.0532 0.0315
38 0.0522 0.0314
39 0.0511 0.0313
40 0.0509 0.0313
41 0.0491 0.0312
42 0.0490 0.0309
43 0.0482 0.0303
44 0.0473 0.0301
45 0.0458 0.0300
46 0.0457 0.0300
47 0.0451 0.0299
48 0.0445 0.0284
49 0.0435 0.0283
50 0.0428 0.0281
51 0.0409 0.0280
52 0.0398 0.0275
53 0.0370 0.0272
54 0.0344 0.0272
55 0.0292 0.0270
56 0.0277 0.0263
57 0.0260 0.0262
58 0.0258 0.0256
59 0.0172 0.0244
60 0.0091 0.0240
61 0.0062 0.0231
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:53 AM Page 11
Duration Flows
The Facility PASSED
Flow(cfs)Predev Mit Percentage Pass/Fail
0.0329 17560 14384 81 Pass
0.0342 16164 11349 70 Pass
0.0355 14964 10374 69 Pass
0.0368 13854 9390 67 Pass
0.0381 12814 8393 65 Pass
0.0394 11813 7486 63 Pass
0.0407 10900 6714 61 Pass
0.0420 10119 6000 59 Pass
0.0433 9385 5371 57 Pass
0.0446 8731 4631 53 Pass
0.0459 8143 3899 47 Pass
0.0472 7593 3598 47 Pass
0.0485 7060 3322 47 Pass
0.0498 6590 3189 48 Pass
0.0511 6147 3061 49 Pass
0.0524 5775 2920 50 Pass
0.0537 5431 2742 50 Pass
0.0550 5097 2618 51 Pass
0.0563 4808 2520 52 Pass
0.0576 4524 2398 53 Pass
0.0589 4252 2259 53 Pass
0.0601 4017 2152 53 Pass
0.0614 3782 1981 52 Pass
0.0627 3548 1818 51 Pass
0.0640 3337 1718 51 Pass
0.0653 3138 1611 51 Pass
0.0666 2952 1513 51 Pass
0.0679 2785 1418 50 Pass
0.0692 2597 1321 50 Pass
0.0705 2447 1212 49 Pass
0.0718 2304 1093 47 Pass
0.0731 2162 1005 46 Pass
0.0744 2025 923 45 Pass
0.0757 1898 854 44 Pass
0.0770 1790 796 44 Pass
0.0783 1687 730 43 Pass
0.0796 1586 661 41 Pass
0.0809 1483 597 40 Pass
0.0822 1379 560 40 Pass
0.0835 1292 514 39 Pass
0.0848 1217 471 38 Pass
0.0861 1155 447 38 Pass
0.0874 1098 418 38 Pass
0.0887 1048 390 37 Pass
0.0900 997 367 36 Pass
0.0913 930 330 35 Pass
0.0926 883 287 32 Pass
0.0938 837 265 31 Pass
0.0951 789 244 30 Pass
0.0964 743 218 29 Pass
0.0977 713 204 28 Pass
0.0990 668 194 29 Pass
0.1003 632 188 29 Pass
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:39:53 AM Page 12
0.1016 596 178 29 Pass
0.1029 566 164 28 Pass
0.1042 539 150 27 Pass
0.1055 497 146 29 Pass
0.1068 473 144 30 Pass
0.1081 434 140 32 Pass
0.1094 399 137 34 Pass
0.1107 371 134 36 Pass
0.1120 349 128 36 Pass
0.1133 324 117 36 Pass
0.1146 297 112 37 Pass
0.1159 275 106 38 Pass
0.1172 257 103 40 Pass
0.1185 235 95 40 Pass
0.1198 218 87 39 Pass
0.1211 198 83 41 Pass
0.1224 181 78 43 Pass
0.1237 158 75 47 Pass
0.1250 145 70 48 Pass
0.1262 130 64 49 Pass
0.1275 119 58 48 Pass
0.1288 109 54 49 Pass
0.1301 97 49 50 Pass
0.1314 91 47 51 Pass
0.1327 82 45 54 Pass
0.1340 76 42 55 Pass
0.1353 69 41 59 Pass
0.1366 61 40 65 Pass
0.1379 54 37 68 Pass
0.1392 48 36 75 Pass
0.1405 41 35 85 Pass
0.1418 38 33 86 Pass
0.1431 33 31 93 Pass
0.1444 27 28 103 Pass
0.1457 22 20 90 Pass
0.1470 21 17 80 Pass
0.1483 20 15 75 Pass
0.1496 19 10 52 Pass
0.1509 17 3 17 Pass
0.1522 14 0 0 Pass
0.1535 12 0 0 Pass
0.1548 9 0 0 Pass
0.1561 4 0 0 Pass
0.1574 3 0 0 Pass
0.1587 3 0 0 Pass
0.1599 3 0 0 Pass
0.1612 3 0 0 Pass
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:40:21 AM Page 16
Appendix
Predeveloped Schematic
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A
Peck WWHM (2024-11-04)12/5/2024 8:40:26 AM Page 17
Mitigated Schematic
Docusign Envelope ID: B29EB968-C739-45B8-8E1F-7522EE3C1A3A