HomeMy WebLinkAboutYelm Crossing-Preliminary Stormwater ReportYelm Crossing
16930 State Route 507 SE, Yelm, WA
Parcel No 64303100900
NE ¼ of the NW ¼ & A portion of the SE ¼ of the NW 1/4, S29, T17 N, R02E,
WM, Thurston County, WA
Stormwater Site Plan – Preliminary Drainage Report
November 2025
JKA Civil Engineering Inc.
950 Broadway, Suite 305
Tacoma, WA 98402
Ph: (253) 539-1400
E-mail: jkawills@gmail.com
Yelm Crossing
SSP – Preliminary Drainage Report
Prepared for: Stefan & Gunnar Gehring
10910 26th Avenue South
Lakewood, WA 98499
(253) 606-2639
Attn: Gunnar Gehring
gunnar@pugetpaving.com
Prepared by: JKA Civil Engineering Inc.
950 Broadway Suite 305
Tacoma, WA 98402
(253) 539-1400
jkawills@gmail.com
JKA Project No.: 2414
JKA File No.: P:\2414\Reports\SSP\2402 SSP.doc
11-6-2025
Project Engineer’s Certification:
I hereby state that this Drainage Report for Yelm Crossing located at 16930 SR 507 has been
prepared by me or under my supervision and meets the minimum standard of care and expertise
which is usual and customary in this community for professional engineers. I understand that the City
of Yelm does not and will not assume liability for the sufficiency, suitability, or performance of
drainage facilities prepared by me.
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Table of Contents
Page
SECTION 1 - PROPOSED PROJECT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . 1
SECTION 2 - EXISTING CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SECTION 3 - INFILTRATION RATES/SOILS REPORT . . . . . . . . . . . . . . . . . . . . . . 8
SECTION 4 - WELLS AND SEPTIC SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SECTION 5 - FUEL TANKS . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 9
SECTION 6 - SUB-BASIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
SECTION 7 – FLOODPLAIN ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
SECTION 8 - AESTHETIC CONSIDERATIONS FOR FACILITIES. . . . . . . . . . . . . . . 9
SECTION 9 – FACILITY SIZING AND DOWNSTREAM ANALYSIS. . . . . . . . . . . . . . 9
SECTION 10 – UTILITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SECTION 11 – CONVENANTS, DEDICATIONS AND EASEMENTS . . . . . . . . . . 10
SECTION 12 – PROPERTY OWNERS ASSOCIATION ARTICLES OF
INCORPORATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
SECTION 13 – OTHER PERMITS OR CONDITIONS PLACED ON THE
PROJECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 10
Appendices
I Project Soils Evaluation and Groundwater Monitoring Data
III Stormwater Calculations and Basin Maps (FINAL ENGINEERING)
IV Source Control BMPs (FINAL ENGINEERING
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SSP - DRAINAGE REPORT
(Note: This report has been prepared in accordance with the Department of Ecology’s 2024 Stormwater
Management Manual for Western Washington)
SECTION I - PROPOSED PROJECT DESCRIPTION
The project proponent is applying for site plan review prior to on-site grading and utility permits.
The project will include a new access road for five new commercial pads. Onsite improvements
include a paved access road with cement concrete curb and gutter, sidewalk, closed drainage,
stormwater collection/conveyance/ infiltration system and sewer, water, and dry utilities.
The project is currently served by the City of Yelm for water or sewer. Construction will include
domestic and fire supply water from a new water main extension; the point of connection will be
at SR 507 and SR 510. All buildings shall be served with a water service line and meter. A
STEP system will be installed to serve each building. The STEP system forcemain will connect
to an existing 6” diameter sewer forcemain located in SR 507.
The goal of this SSP is to obtain City of Yelm site plan review approvals to allow for submittal of
site development permits.
A tabulation of surfaces for the existing site and proposed development will be provided during
final engineering as too much is unknown for the uses of the site:
Project Area Tabulation
Item On-Site Off-Site Total
Total Project Area (ft²)
Ex Roof (SF)
Ex Driveway (SF)
Ex Walks, Porches, Conc Pads (SF)
Ex Total Impervious (SF)
Existing Pervious (ft²)
Existing Hard Surface to remain (ft²)
Amount of New Roof area (ft²)
New sidewalk and misc hard surface (SF)
Amount of New Driveway (ft²)
Replaced Driveway (SF)
Amount of New Hard Surface (ft²)
Amount of Replaced Hard Surface (ft²)
Amount of New + Replaced Hard Surface (ft²)
Amount of New Pollution Generating Hard Surface
Amount of Replaced PGHS (ft²)
Amount of New + Replaced PGHS (ft²)
Hard Surfaces to Pervious Surface (ft²)
Amount of Land Disturbed (ft²)
Native Vegetation to Lawn/Landscaped (acres)
Native Vegetation to Pasture (acres)
Value of Proposed Improvements ($) TBD TBD TBD
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Assessed Value of Existing Site Improvements ($) 0 0 0
Amount to be Graded/Filled (cubic yards)
Proposed Stormwater System –
The storm drainage mitigation objectives for this commercial development are to control runoff
of the development area by virtue of:
All new roof areas will be directed to individual downspout infiltration trenches
located on each pad.
All individual pad developments will have separate water quality and infitlration
systems to collect, treat, and infiltrate runoff from their associated parking areas.
Curb/gutter and sidewalk road improvements areas on-site will have drainage
collected and conveyed to a water quality treatment system then into an infiltration
faciltiy separate from the pad specific systems.
All areas of the site that will be disturbed, but not covered with roof or other hard
surfacing, will have soil amended and/or well-draining topsoil placed to promote
infiltration/evaporation of precipitation on individual pads.
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The project is required to address all minimum requirements because the project results in more
than 5,000 SF of new plus replaced hard surface area. The project is designed to meet the
intent of these requirements as follows:
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Minimum Requirement #1 - Preparation of Stormwater Site Plans
The project meets requirement #1 by preparation of this drainage report and the ‘Drainage
Control Plans’ (aka JKA civil sheets).
Minimum Requirement #2 - Construction Stormwater Pollution Prevention
The project is designed to meet the intent of Construction SWPPP Elements #1 through
#13 as detailed in Volume 1 - Chapter 3 of 2024 DOE Stormwater Management Manual for
Western Washington. The 13 elements are summarized below.
1. Preserve Vegetation/Mark Clearing Limits
2. Establish Construction Access
3. Control Flow Rates
4. Install Sediment Controls
5. Stabilize Soils
6. Protect Slopes
7. Protect Drain Inlets
8. Stabilize Channels and Outlets
9. Control Pollutants
10. Control Dewatering
11. Maintain BMPs
12. Manage the Project
13. Protect Low Impact Development (LID) BMP’s
These elements are discussed in the SWPPP Report for the project. The SWPPP
Report will be prepared during final engineering.
Minimum Requirement #3 – Source Control of Pollution
Source control BMP’s are structures or an operation that is intended to prevent pollutants
from coming into contact with stormwater through physical separation of areas or careful
management of activities that are sources of pollutants. There are two types of source
control BMPs; structural and operational.
Operational BMPs are non-structural practices that prevent or reduce pollutants from
entering stormwater.
Operational Source Control BMP’s for this residential project include:
Preventive maintenance procedures
Spill prevention and clean up
Good housekeeping practices
Structural source control BMPs are physical, structural, or mechanical devices or facilities
that are intended to prevent pollutants from entering stormwater.
Minimum Requirement #4 – Preservation of Natural Drainage Systems and Outfalls
This requirement is met by employing onsite BMP’s such as tightlining and directing roof
drainage to downspout infiltration trenches and infiltration of road and driveway runoff in the
infiltration galleries. Using these BMP’s will maintain natural and existing drainage patterns
and discharges from the project site to the maximum extent practicable.
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This development is a flat site with well-draining soils, thus existing conditions have no
drainage systems or outfalls. The developed condition will continue this drainage pattern
by infiltration of the entire site (either into the infiltration trenches, or simply into the well-
draining soil of the landscaping).
Minimum Requirement #5 – On-site Stormwater Management
2024 DOE SWMM Minimum Req #5:
“All projects that require Minimum Requirement #5 (per the Project Thresholds in I-3.3 Applic-ability
of the Minimum Requirements) must employ Stormwater Management BMPs as detailed below. The
compliance options for the project depend on the amount of improvements
proposed, the location of the project, the size of the parcel the project is on, and
whether or not the project is Flow Control exempt.
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This project triggers Min Req’s #1 – 9; thus, the project will use both onsite stormwater
management BMPs and onsite infiltration to meet the LID performance standard.
Low Impact Development Performance Standard:
Stormwater discharges shall match developed discharge durations to pre-developed
durations for the range of pre-developed discharge rates from 8 percent of the 2-year peak
flow to 50 percent of the 2-year peak flow. Refer to the Standard Flow Control
Requirements section in Minimum Requirement #7 for information about the assignment of
the pre-developed condition. Project sites that must also meet Minimum Requirement #7 –
flow control – must match flow durations between 8 percent of the 2-year flow through the
full 50-year flow.
Based on the proposed site plan, topography, and soils, the selected BMP’s for
meeting Requirement #5 are: soil amendment for the lawn and landscape areas;
tightlined roof drains to individual downspout infiltration trenches; infiltration of
runoff from sidewalks, driveways, and roadway pavement within infiltration systems.
Minimum Requirement #6 – Runoff Treatment
Threshold Discharge Areas (TDA’s) that have a total of 5,000 SF or more of pollution-
generating hard surface (PGHS) are required to provide runoff treatment.
Stormwater treatment is proposed for this project for the driveways and road pavement and
parking areas.
Runoff BMP options for basic treatment were reviewed in the SWMM. The BMP’s
considered were:
Manufactured Treatment Devices (such as Old Castle BioPod)
Water quality treatment systems will be designed per Ecology requirements during final
engineering.
Minimum Requirement #7 – Flow Control
Flow control is provided by infiltrating onsite precipitation/runoff within the infiltration
trenches, and soil amendment (infiltration and transpiration/evaporation). In addition, runoff
from roof areas will be directed to individual pad downspout infiltration trenches located on
each pad.
Infiltration calculations will be provided during final engineering.
Minimum Requirement #8 – Wetlands Protection
Not applicable. No wetlands exist on or near the site.
Minimum Requirement #9 – Operations and Maintenance
A stormwater maintenance plan will be prepared as part of the final SSP. It will describe
the necessary maintenance required for the collection, conveyance, infiltration, and
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treatment systems proposed for this project. The Operations and Maintenance Manual will
be prepared as a separate document.
The BioPod units will be maintained per the manufacturer’s recommendations.
SECTION 2 - EXISTING CONDITIONS
The 7.1 -acre site consists of one unoccupied rectangular parcel with no existing structures or
improvements. Topography is generally flat with a general elevation of 355’. Vegetation
consists mostly of field grasses, shrubs, and some trees.
Current access is off SR 507 and Walmart Boulevard.
SECTION 3 - INFILTRATION RATES/SOILS REPORT
The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey indicates that the
site is underlain by Spanaway gravelly sandy loam (110) and Spanaway stony sandy loam (112)
soils. Spanaway soils are derived from volcanic ash over gravelly outwash. These soils have
are generally excessively well drained and are included in hydrologic soils group A.
On October 10, 2023, Terra Associates, Inc. visited the site and monitored the excavation of
seven test pits and three borings. See Appendix I for the soils report.
They found the soils to be Spanaway series as mapped. Test pits were excavated to a
maximum depth of 108” below existing grade and borings were drilled to a maximum depth of
25 feet. Grain size analysis was used to determine design infiltration rates of 20 in/hr. The
seasonal high groundwater was found to be 16-feet below existing grade.
SECTION 4 - WELLS AND SEPTIC SYSTEMS
There is one observation well known to exist on the site and will be decommissioned with this
development.
The project will derive domestic and fire water supply from City of Yelm with a new main
extension into the site. Fire hydrants will be placed pursuant to City preferences and homes
shall have sprinkler systems installed.
There are no known septic systems on-site. The site will be served by City of Yelm sewer.
SECTION 5 - FUEL TANKS
No underground fuel tanks are known to exist. If such tanks are found, they will be abandoned
or removed in accordance with current DOE regulations.
SECTION 6 - SUB-BASIN DESCRIPTION
There is no significant offsite drainage tributary to the project’s developable area.
SECTION 7 – FLOOD PLAIN ANALYSIS
Review of Thurston County Geodata mapping indicates that the proposed development is
outside any areas indicated as 100-year flood zone.
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SECTION 8 – AESTHETIC CONSIDERATIONS FOR FACILITIES
The site will be landscaped as appropriate.
SECTION 9 – FACILITY SIZING AND DOWNSTREAM ANALYSIS
Proposed stormwater BMP's for the commercial development encourages infiltration and
evaporation of site precipitation by amending soil and utilizing roof drain infiltration. Primary
stormwater BMP’s will consists of treatment and infiltration of PGHS areas. Downstream
analysis is not needed due to 100% infiltration onsite.
Facility sizing will be performed during final engineering.
SECTION 10 – UTILITIES
Stormwater quantity control measures such as roof drain piping, and the infiltration trenches will
be located away from other utilities as much as possible; however, conflicts may occur during
construction. The contractor and owner are advised to inform the project engineer if conditions
are encountered which could affect the storm drainage systems, as designed, due to utility
conflicts.
SECTION 11 – CONVENANTS, DEDICATIONS AND EASEMENTS
Onsite drainage facilities including catch basins, piping, and downspout infiltration trenches will
require routine maintenance. The responsibility for maintenance will lie with the property owner
and/or their project management team.
SECTION 12 – PROPERTY OWNERS ASSOCIATION ARTICLES OF
INCORPORATION
A Homeowners Association will not be needed as this is a commercial development.
SECTION 13 – OTHER PERMITS OR CONDITIONS PLACED ON THE PROJECT
Besides a site development permit required for grading, drainage, paving, access, and erosion
control improvements, the following approvals may also be required:
City of Yelm - Building permits
City of Yelm – Sewer Main Extension
Puget Sound Energy – Power service
City of Yelm - Water service
WA State DOE - UIC Program
WSDOT – ROW Permit
UIC Program discussion:
The Washington State Department of Ecology has an underground injection control (UIC)
program (chapter 17-218 WAC) that has requirements related to the infiltration trench proposed
on this project. The individual roof drain infiltration trenches are not classified as UIC wells, but
the infiltration trench designed to accept road runoff does meet the definition of a UIC well and
will require the project owner to register it with the DOE.
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The UIC program is described on the Ecology website. According to the website, “all injection
wells must either receive a program rule authorization or a state discharge permit in order to
operate.” Injection wells used for stormwater runoff are considered Class V wells.
Ecology defines injection wells as follows:
“Underground Injection Control (UIC) wells — or injection wells — are structures built to allow
fluids to flow into the ground (usually) under the force of gravity. The most common in
Washington are known as drywells.
An injection well is designed and built:
Deeper than the largest surface dimension.
To contain an assemblage of perforated pipe.
As an improved sinkhole.
As a chamber or vault designed to capture and infiltrate stormwater.
Examples include: sump pump, drywell, drainfield, an infiltration trench containing perforated
pipe, a stormwater chamber, and temporary injection points.”
The DOE’s website section on UIC wells refers to the EPA website for facilities that they
regulate as injection wells; that table from the EPA is shown below:
The table above does describe that an infiltration trench would “probably be considered a Class
V injection well”. This is because the perforated pipe runs the length of the trench to distribute
water “below the surface of the ground”.
The UIC Program has two requirements:
1. The non-endangerment standard of WAC 173-218-080 must be met at all times,
prohibiting discharges that allow movement of fluids containing contaminants to
reach the ground-water.
2. All UIC facility owners/operators must register their UIC well(s) using Ecology's
online registration application that can be found at the following web address:
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https://ecology.wa.gov/Regulations-Permits/Guidance-technical-
assistance/Underground-injection-control-program/Register-UIC-wells-online
Appendix I
Project Soils Evaluation
GEOTECHNICAL REPORT
Visconsi SR 507 Retail
16930 SR 507 Southeast
Yelm, Washington
Project No. T-8944
Prepared for:
Visconsi Companies, Ltd
Pepper Pike, Ohio
October 10, 2023
Final Draft May 16, 2024
5-16-2024
TABLE OF CONTENTS
Page No.
1.0 Project Description .......................................................................................................... 1
2.0 Scope of Work ................................................................................................................ 1
3.0 Site Conditions ................................................................................................................ 2
3.1 Surface ............................................................................................................... 2
3.2 Soils .................................................................................................................... 2
3.3 Groundwater ...................................................................................................... 2
3.4 Geologically Hazardous Areas ........................................................................... 3
3.4.1 Erosion Hazard Areas .............................................................................. 3
3.4.2 Landslide Hazard Areas ........................................................................... 4
3.4.3 Seismic Hazard Areas .............................................................................. 4
3.5 Seismic Site Class .............................................................................................. 5
4.0 Discussion and Recommendations .................................................................................. 5
4.1 General ............................................................................................................... 5
4.2 Site Preparation and Grading ............................................................................. 6
4.3 Excavations ........................................................................................................ 7
4.4 Foundations ........................................................................................................ 7
4.5 Slab-on-Grade Floors ......................................................................................... 8
4.6 Infiltration Feasibility ........................................................................................ 8
4.7 Stormwater Facilities ......................................................................................... 9
4.8 Drainage ............................................................................................................. 9
4.9 Utilities ............................................................................................................. 10
4.10 Pavements ........................................................................................................ 10
5.0 Additional Services ....................................................................................................... 11
6.0 Limitations .................................................................................................................... 11
Figures
Vicinity Map ........................................................................................................................ Figure 1
Exploration Location Plan ................................................................................................... Figure 2
Depth to Groundwater Hydrographs .................................................................................... Figure 3
Appendix
Field Exploration and Laboratory Testing ........................................................................ Appendix A
Geotechnical Report
Visconsi SR 507 Retail
Yelm, Washington
1.0 PROJECT DESCRIPTION
We understand that the proposed project is a retail development with associated infrastructure improvements. Site
development and building plans are currently not available. The recommendations in the following sections of this
report are based on our understanding of the proposed development. We should review design drawings as they
become available to verify our recommendations have been properly interpreted and to supplement them, if
required.
2.0 SCOPE OF WORK
We explored subsurface conditions at the site in seven test pits excavated to depths ranging from about 8 to 9 feet
below ground surface using a track-mounted excavator and in three test borings drilled to maximum depths ranging
between about 15 and 25 feet with a track-mounted drill rig using hollow-stem auger drilling methods. Groundwater
monitoring wells were installed in each of the test borings subsequent to drilling and sampling.
Using information obtained from the subsurface explorations and the results of laboratory testing, we performed
analyses to develop geotechnical recommendations for project design and construction. Specifically, this report
addresses the following:
Soil and groundwater conditions.
Geologic hazards per the City of Yelm Municipal Code.
Seismic Site Class per the current International Building Code (IBC).
Site preparation and grading.
Excavations.
Foundations.
Slab-on-grade floors.
Infiltration Feasibility.
Stormwater Facilities.
Utilities.
Pavements.
It should be noted that recommendations outlined in this report regarding drainage are associated with soil strength,
design earth pressures, erosion, and stability. Design and performance issues with respect to moisture as it relates
to the structure environment are beyond Terra Associates’ purview. A building envelope specialist or contractor
should be consulted to address these issues, as needed.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 2
3.0 SITE CONDITIONS
3.1 Surface
The site is vacant 8.59-acre parcel located northwest of and adjacent to the intersection of State Route 507 (SR 507)
and Walmart Boulevard SE in Yelm, Washington. The site location is shown on Figure 1.
Site topography is relatively flat. Elevation contours obtained for the site using the Thurston GeoData Center online
mapping website (https://www.thurstoncountywa.gov/departments/geodata-center) shows a topographic relief of
about seven feet between the southwestern and northeastern site corners. Site vegetation consists mainly of grasses
and brush with several mature coniferous trees and younger deciduous trees scattered about the northwestern and
southern portions of the site, respectively.
Review of historical aerial photographs available on Google Earth shows a residence and several farm outbuildings
occupying the southern portion of the site until mid-2006. We observed several small piles of wood debris in the
southern portion of the site that appear to be related to the previous development.
3.2 Soils
The native soils observed in the subsurface explorations consist primarily of sand and gravel with variable minor
proportions of silt, cobbles, and boulders that are interpreted to be glacial recessional outwash deposits. Based on
our test pit observations, the soils are generally in a loose to medium dense condition, and are generally dry above
depths of about five to seven feet.
The Geologic map of the McKenna and northern half of the Lake Lawrence 7.5-minute quadrangles, Thurston and
Pierce Counties, Washington by M. Polenz et al., dated December 2022, shows the site and adjacent properties
underlain by recessional or proglacial outwash gravel (Qgog). These deposits are described as loose pebbles,
cobbles, and boulders, in various amounts, commonly with sandy matrix and sand lenses or interbeds. The native
deposits observed in the test pits and test borings are generally consistent with this geologic map unit.
Detailed descriptions of the conditions observed in the subsurface explorations are presented on the Test Pit Logs
and Boring Logs in Appendix A. The approximate locations of the subsurface explorations are shown on Figure 2.
3.3 Groundwater
Groundwater was not encountered in any of the test pits or test borings at the time our field work was completed.
Review of drillers logs on file with the Washington State Department of Ecology (DOE) shows static water levels
in wells located about 3,000 to 6,000 feet from the site ranging between depths of about 29 feet and 57 feet.
Subsequent well construction automated dataloggers were installed in each well and set to record groundwater
levels should they develop daily at two-hour intervals.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 3
Instrument depths below the ground surface at each well are as follows:
Well ID Instrument Depth (feet)
B-1 24.03
B-2 15.52
B-3 21.46
The data loggers were retrieved and downloaded on May 6, 2024. Review of the data shows groundwater rising to
the elevation of the B-1 instrument on December 10, 2023 and at the B-3 instrument on December 15, 2023.
Groundwater never rose to the level of the instrument installed in B-2. The shallowest depth to groundwater was
recorded in early February 2024 with water at a depth of 16.79 feet and 16.72 feet at wells B-1 and B-3 respectively.
Hydrographs of the data showing the seasonal fluctuation are attached as Figure 3.
3.4 Geologically Hazardous Areas
We evaluated site conditions for the presence of geologic hazards as designated in Section 18.21.100 (Geologically
hazardous areas) of the Yelm Municipal Code (YMC). YMC Chapter 18.21.100.B specifically designates erosion
hazard areas, landslide hazard areas, and seismic hazard areas as geologically hazardous areas.
3.4.1 Erosion Hazard Areas
YMC Chapter 18.21.100.B.1 defines erosion hazard areas as “…at least those areas identified by the U.S.
Department of Agriculture’s Natural Resources Conservation Service as having a “moderate to severe,” “severe,”
or “very severe” rill and inter-rill erosion hazard. Rill or inter-rill are areas subject to sheet wash, or steep-sided
channels resulting from accelerated erosion. Erosion hazard areas are also those areas impacted by shoreland and/or
streambank erosion and those areas within a river’s channel migration zone.”
The NRCS has mapped the site soils as Spanaway gravelly sandy loam, zero to three percent slopes, which are
described as having a slight erosion hazard. Based on the NRCS soil mapping, and considering that the site is not
susceptible to shoreland and/or streambank erosion or located within a river’s channel migration zone, erosion
hazards meeting the above defining criteria do not exist at the site.
Although not defined as an erosion hazard area, the potential for soil erosion at the site will increase during
construction. In our opinion, proper implementation, and maintenance of Best Management Practices (BMPs) for
erosion prevention and sediment control will adequately mitigate the erosion potential in the planned development
area. BMPs for erosion prevention and sediment control must be in place prior to and throughout grading activity
at the site.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 4
3.4.2 Landslide Hazard Areas
YMC Chapter 18.21.100.B.2 defines landslide hazard areas as “…areas potentially subject to landslides based on a
combination of geologic, topographic, and hydrologic factors. They include areas susceptible because of any
combination of bedrock, soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Examples of
these may include, but are not limited to, the following:
a.Areas of historic failures;
b.Areas with all three of the following characteristics:
i.Slopes steeper than 15 percent;
ii.Hillsides intersecting geologic contacts with a relatively permeable sediment overlying a relatively
impermeable sediment or bedrock; and
iii.Springs or ground water seepage;
c.Areas that have shown movement during the Holocene epoch (from 10,000 years ago to the present) or that
are underlain or covered by mass wastage debris of that epoch;
d.Slopes that are parallel or subparallel to planes of weakness (such as bedding planes, joint systems, and
fault planes) in subsurface materials;
e.Slopes having gradients steeper than 80 percent, subject to rock fall during seismic shaking;
f.Areas potentially unstable because of rapid stream incision, streambank erosion, and undercutting by wave
action;
g.Areas that show evidence of or are at risk from snow avalanches;
h.Areas located in a canyon or on an active alluvial fan, presently or potentially subject to inundation by
debris flows or catastrophic flooding; and
i.Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet, except areas
composed of consolidated rock. A slope is delineated by establishing its toe and top and is measured by
averaging the inclination over at least ten feet of vertical relief.”
Conditions meeting the above criteria do not exist at the site. Therefore, no potential landslide hazards exist at the
site.
3.4.3 Seismic Hazard Areas
YMC Chapter 18.21.100.B.3 defines seismic hazard areas as “…areas subject to severe risk of damage as a result
of earthquake induced ground shaking, slope failure, settlement, soil liquefaction, lateral spreading, or surface
faulting. One indicator of potential for future earthquake damage is a record of earthquake damage in the past. Ground
shaking is the primary cause of earthquake damage in Washington.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 5
The strength of ground shaking is primarily affected by:
a.The magnitude of an earthquake;
b.The distance from the source of an earthquake;
c.The type of thickness of geologic materials at the surface; and
d.The type of subsurface geologic structure.”
The Washington State Department of Natural Resources (DNR) Geologic Information Portal website
(https://www.dnr.wa.gov/geologyportal) shows the nearest fault suspected of Quaternary activity (designated
“Class B”) located over four miles southwest of the site. Based on its proximity to the site, there is a low risk of
surface rupture at the site during a seismic event along this fault line.
Based on the observed surface and subsurface site conditions, it is our opinion that the risk for damage resulting
from earthquake induced slope failure, settlement, soil liquefaction, and lateral spreading to occur at the site is
negligible. In our opinion, unusual seismic hazards do not exist at the site, and potential impacts associated with
ground shaking would be adequately mitigated by designing in accordance with local building codes.
3.5 Seismic Site Class
Based on the site soil conditions and our knowledge of the area geology, per the current International Building Code
(IBC), site class “D” should be used in structural design.
4.0 DISCUSSION AND RECOMMENDATIONS
4.1 General
Based on our study, it is our opinion that the planned development is feasible from a geotechnical engineering
standpoint. In general, buildings can be supported on conventional spread footings bearing on competent native
soils, or on structural fill placed on a competent native soil subgrade. Floor slabs and pavements can be similarly
supported.
The upper approximately one and one-half feet of soil observed in most of the test pits contain a sufficient amount
of soil fines that will make the soils difficult to compact as structural fill when too wet. The ability to use these
upper soils as structural fill will depend on the soil moisture content and the prevailing weather conditions at the
time of construction. The contractor should be prepared to dry the soils by aeration during the normally dry summer
season to facilitate compaction as structural fill. Alternatively, stabilizing the moisture in the native soil with cement
or lime can be considered. If grading activities will take place during the winter season, the contractor should be
prepared to import clean granular material for use as structural fill and backfill. The underlying outwash gravel and
sand soils should be suitable for use as structural fill under most conditions.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 6
Detailed recommendations regarding these issues and other geotechnical design considerations are provided in the
following sections. These recommendations should be incorporated into the final design drawings and construction
specifications.
4.2 Site Preparation and Grading
To prepare the site for construction, all vegetation, organic surface soils, and other deleterious material should be
stripped and removed from the site. Existing relic building elements, pavements, and buried utilities should also be
removed. Abandoned utility pipes that fall outside of new building areas can be left in place provided they are
sealed to prevent intrusion of groundwater seepage and soil. Given current site conditions, we expect stripping
depths of about four to six inches will be required to remove the surficial organic soils.
Once stripping operations are complete, cut and fill operations can be initiated to establish desired building grades.
Prior to placing fill, all exposed bearing surfaces should be observed by a representative of Terra Associates, Inc.
to verify soil conditions are as expected and suitable for support of new fill or building elements. Our representative
may request a proofroll using heavy rubber-tired equipment to determine if any isolated soft and yielding areas are
present. If excessively yielding areas are observed, and they cannot be stabilized in place by compaction, the
affected soils should be excavated and removed to firm bearing and grade restored with new structural fill. If the
depth of excavation to remove unstable soils is excessive, the use of geotextile fabrics, such as Mirafi 500X, or an
equivalent fabric, can be used in conjunction with clean granular structural fill. Our experience has shown that, in
general, a minimum of 18 inches of a clean, granular structural fill place and compacted over the geotextile fabric
should establish a stable bearing surface.
Our study indicates that most of the near-surface soils contain a sufficient percentage of fines (silt and clay size
particles) that may make them difficult to compact as structural fill if they are too wet or too dry. Accordingly, the
ability to use these native soils from site excavations as structural fill will depend on their moisture content and the
prevailing weather conditions when site grading activities take place. At the time of our study, the soils in the upper
approximately five to seven feet were typically dry and would require the addition of water to facilitate adequate
compaction. Native soils that are too wet to properly compact could be dried by aeration during dry weather
conditions or mixed with an additive such as cement or lime to stabilize the soil and facilitate compaction. If an
additive is used, additional Best Management Practices (BMPs) for its use will need to be incorporated into the
Temporary Erosion and Sedimentation Control plan (TESC) for the project. Soils that are dry of optimum should
be moisture conditioned by controlled addition of water and blending prior to material placement. The relatively
clean outwash gravel and sand should be suitable for use as structural fill under most conditions provided the soils
are free of large diameter cobbles and boulders.
If grading activities are planned during the wet winter months, or if they are initiated during the summer and extend
into fall and winter, the owner should be prepared to import wet weather structural fill. For this purpose, we
recommend importing a granular soil that meets the following grading requirements:
U.S. Sieve Size Percent Passing
6 inches 100
No. 4 75 maximum
No. 200 5 maximum*
* Based on the 3/4-inch fraction.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 7
Prior to use, Terra Associates, Inc. should observe and test all materials imported to the site for use as structural fill.
Structural fill should be placed in uniform loose layers not exceeding 12 inches and compacted to a minimum of 95
percent of the soil’s maximum dry density, as determined by American Society for Testing and Materials (ASTM)
Test Designation D-698 (Standard Proctor). The moisture content of the soil at the time of compaction should be
within two percent of its optimum, as determined by this ASTM standard. In nonstructural areas, the degree of
compaction can be reduced to 90 percent.
4.3 Excavations
All excavations at the site associated with confined spaces, such as utility trenches, must be completed in accordance
with local, state, and federal requirements. Based on regulations outlined in the Washington Industrial Safety and
Health Act (WISHA), the native outwash deposits would be classified as Type C soil.
Accordingly, temporary excavations in Type C soils should have their slopes laid back at an inclination of 1.5:1
(Horizontal: Vertical) or flatter. All exposed temporary slope faces that will remain open for an extended period of
time should be covered with a durable reinforced plastic membrane during construction to prevent slope raveling
and rutting during periods of precipitation.
The above information is provided solely for the benefit of the owner and other design consultants, and should not
be construed to imply that Terra Associates, Inc. assumes responsibility for job site safety. It is understood that job
site safety is the sole responsibility of the project contractor.
4.4 Foundations
In our opinion, buildings may be supported by conventional spread footing foundations bearing on a subgrade that
is prepared as recommended in Section 4.2 of this report. Foundations exposed to the weather should bear at a
minimum depth of one and one-half feet below adjacent grades for frost protection. Interior foundations can be
supported at any convenient depth below the floor slab.
We recommend designing foundations for a net allowable bearing capacity of 3,000 psf. For short-term loads, such
as wind and seismic, a one-third increase in this allowable capacity can be used. Total and differential settlements
should not exceed one-inch and one-half inch, respectively. The predicted settlements would be immediate in
nature, occurring as building loads are applied.
For designing foundations to resist lateral loads, a base friction coefficient of 0.35 can be used. Passive earth
pressures acting on the sides of the footings can also be considered. We recommend calculating this lateral
resistance using an equivalent fluid weight of 300 pcf. We do not recommend including the upper 12 inches of soil
in this computation because it can be affected by weather or disturbed by future grading activity. This value assumes
the foundation will be backfilled with structural fill, as described in Section 4.2 of this report. The values
recommended include a safety factor of 1.5.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 8
4.5 Slab-on-Grade Floors
Slab-on-grade floors may be supported on subgrades prepared as recommended in Section 4.2 of this report.
Immediately below the floor slabs, we recommend placing a four-inch thick capillary break layer of clean,
free-draining, coarse sand or fine gravel that has less than three percent passing the No. 200 sieve. This material
will reduce the potential for upward capillary movement of water through the underlying soil and subsequent
wetting of the floor slabs.
The capillary break layer will not prevent moisture intrusion through the slab caused by water vapor transmission.
Where moisture by vapor transmission is undesirable, such as covered floor areas, a common practice is to place a
durable plastic membrane on the capillary break layer and then cover the membrane with a layer of clean sand or
fine gravel to protect it from damage during construction and aid in uniform curing of the concrete slab. It should
be noted, if the sand or gravel layer overlying the membrane is saturated prior to pouring the slab, it will be
ineffective in assisting uniform curing of the slab and can actually serve as a water supply for moisture transmission
through the slab and affecting floor coverings. Therefore, in our opinion, covering the membrane with a layer of
sand or gravel should be avoided if floor slab construction occurs during the wet winter months and the layer cannot
be effectively drained. We recommend floor designers and contractors refer to the 2003 American Concrete
Institute (ACI) Manual of Concrete Practice, Part 2, 302.1R-96, for further information regarding vapor barrier
installation below slab-on-grade floors.
4.6 Infiltration Feasibility
Based on the results of our subsurface exploration and laboratory test results, it is our opinion that the use of onsite
infiltration for management of stormwater runoff would be feasible.
We determined estimated (initial) saturated hydraulic conductivities (Ksat) for the native soils at various site
locations and depths using the results of grain size analyses as outlined in Volume V, Chapter 5.4 of the Washington
State Department of Ecology (DOE) 2019 Stormwater Management Manual for Western Washington
(SWMMWW). Estimated initial Ksat rates determined by this process are presented below:
Boring Depth (ft) Ksat (in/hr)
TP-1 2 70.35
TP-2 6 246.17
TP-4 4 170.64
B-1 20 25.59
B-2 10 34.59
B-3 15 25.17
in/hr = inches per hour
Design infiltration rates would be based on these estimated initial Ksat values, which are then adjusted with
correction factors related to: 1) site variability and number of test locations (CFv); 2) uncertainty of test method
(CFt); and 3) degree of influent control to prevent siltation and bio-buildup (CFm). We can assist the civil designers
in determining the design infiltration rates once site grading and storm drainage plans are developed.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 9
Based on the results of groundwater monitoring as described in the previous groundwater section of this report, for
design of the infiltration facilities we recommend the seasonal high groundwater be taken at depth of 16 feet from
the current surface elevations.
4.7 Stormwater Facilities
If a pond with above-grade containment berms will be used, the berm locations should be stripped of topsoil, duff, and
soils containing organic material prior to the placement of fill. The fill berms should be constructed by placing
structural fill in layers no more than 12 inches thick, compacting each layer to a minimum of 95 percent relative
compaction, as determined by ASTM Test Designation D-1557 (Modified Proctor). Material used to construct
pond berms should consist predominately of granular soils with a maximum size of 3 inches and a minimum of 20
percent fines. The results of laboratory testing indicate that most of the site soils would not meet this gradational
requirement. Terra Associates, Inc. should examine and test all onsite or imported materials proposed for use as berm
fill prior to their use.
Due to the exposure to fluctuating stored water levels, soils exposed on the interior pond slopes may be subject to
some risk of periodic shallow instability or sloughing. Establishing interior slopes at a gradient of 3:1
(Horizontal:Vertical) will significantly reduce or eliminate this potential. Exterior berm slopes and interior slopes above
the maximum water surface should be graded to a finished inclination no steeper than 2:1 (Horizontal: Vertical).
Finished slope faces should be thoroughly compacted and vegetated to guard against erosion.
Lining the pond with either a compacted soil liner or a flexible membrane liner (FML) would adequately mitigate
the potential for water loss due to infiltration into the coarse sand and gravel if the facility functions as a wet pond.
The liner can consist of soils meeting the gradation recommended above for pond containment berms. A compacted
soil liner should have a minimum thickness of two feet. If a FML is used, we recommend that it have a minimum
thickness of 40 mils. Plastic, HDPE, or composite liners can be considered. The liner should be installed on a
properly prepared subgrade in accordance with the liner manufacturer’s specifications. If the pond slopes are
required to be vegetated, it will be necessary to specify a liner that will exhibit sufficient friction to ensure topsoil
will not slide off the liner when the pond is in service. Alternatively, a geo-cell confinement system could be
installed over the liner and infilled with topsoil. As penetrations through the liner would not be allowed, the geo-
cell system would need to be anchored at the top of the pond in a keyway and supported by tendons that extend
through the geo-cell webbing. Geo-Web cellular confinement or similar systems could be considered for this
purpose.
4.8 Drainage
Surface
Final exterior grades should promote free and positive drainage away from the buildings at all times. Water must
not be allowed to pond or collect adjacent to foundations or within the immediate building areas. If a positive
drainage gradient cannot be provided, surface water should be collected adjacent to the structures and directed to
appropriate stormwater facilities.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 10
Subsurface
We recommend installing perimeter foundation drains adjacent to shallow foundations where paved surfaces do not
extend to the building perimeter and positive drainage away from the structure is not provided. The drains can be
laid to grade at an invert elevation equivalent to the bottom of footing grade. The drains can consist of four-inch
diameter perforated PVC pipe that is enveloped in washed three-quarter-inch gravel sized drainage aggregate. The
aggregate should extend six inches above and to the sides of the pipe. Roof and foundation drains should be
tightlined separately to the storm drains. All drains should be provided with cleanouts at easily accessible locations.
4.9 Utilities
Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or
local jurisdictional requirements. At minimum, trench backfill should be placed and compacted as structural fill as
described in Section 4.2 of this report. As noted, soils excavated onsite should generally be suitable for use as
backfill material. However, some of the near-surface soils are fine grained and moisture sensitive; therefore,
moisture conditioning may be necessary to facilitate proper compaction. If utility construction takes place during
the winter, it may be necessary to import suitable wet weather fill for utility trench backfilling.
4.10 Pavements
Pavements should be constructed on subgrades prepared as recommended in Section 4.2 of this report. Regardless
of the degree of relative compaction achieved, the subgrade must be firm and relatively unyielding before paving.
Proofrolling the subgrade with heavy construction equipment should be completed to verify this condition.
The pavement design section is dependent upon the supporting capability of the subgrade soils and the traffic
conditions to which it will be subjected. We expect traffic at the facility will consist of cars and light trucks, along
with heavy traffic in the form of tractor-trailer-rigs. For design considerations, we have assumed traffic in parking
and in car/light truck access pavement areas can be represented by an 18-kip Equivalent Single Axle Loading
(ESAL) of 50,000 over a 20-year design life. For heavy traffic pavement areas, we have assumed an ESAL of
300,000 would be representative of the expected loading. These ESALs represent loading approximately equivalent
to 3 and 18, loaded (80,000 pound GVW) tractor-trailer rigs traversing the pavement daily in each area, respectively.
With a stable subgrade prepared as recommended for the design ESAL values, we recommend the following
pavement sections:
Light Traffic/Car Access:
Two inches of hot mix asphalt (HMA) over four inches of crushed rock.
Full depth HMA – three and one-half inches.
Heavy Traffic/Truck Access:
Three inches of HMA over six inches of crushed rock.
Full depth HMA – five inches.
October 10, 2023
Final Draft May 16, 2024
Project No. T-8944
Page No. 11
For exterior Portland cement concrete (PCC) pavement, we recommend the following:
6 inches of PCC over 2 inches of crushed surfacing top course.
o 28-day compressive strength – 4,000 psi.
o Control joints spaced at a maximum of 15 feet.
The paving materials used should conform to the Washington State Department of Transportation (WSDOT)
specifications for one-half-inch class HMA, PCC, and CRB.
Long-term pavement performance will depend upon surface drainage. A poorly-drained pavement section will be
subject to premature failure resulting from surface water infiltrating the subgrade soils and reducing their supporting
capability. For optimum performance, we recommend surface drainage gradients of at least two percent. Some
degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular
maintenance should be planned to seal cracks as they occur.
5.0 ADDITIONAL SERVICES
Terra Associates, Inc. should review the final design drawings and specifications in order to verify earthwork and
foundation recommendations have been properly interpreted and implemented in project design. We should also
provide geotechnical services during construction to observe compliance with our design concepts, specifications,
and recommendations. This will allow for design changes if subsurface conditions differ from those anticipated
prior to the start of construction.
6.0 LIMITATIONS
We prepared this report in accordance with generally accepted geotechnical engineering practices. No other
warranty, expressed or implied, is made. This report is the copyrighted property of Terra Associates, Inc. and is
intended for specific application to the Visconsi SR 507 Retail project in Yelm, Washington. This report is for the
exclusive use of Visconsi Companies, Ltd., and their authorized representatives.
The analyses and recommendations presented in this report are based on data obtained from the onsite test pits and
test borings. Variations in soil conditions can occur, the nature and extent of which may not become evident until
construction. If variations appear evident, Terra Associates, Inc. should be requested to reevaluate the
recommendations in this report prior to proceeding with construction.
SITE
REFERENCE: WSDOT GEOPORTAL
Environmental Earth Sciences
Terra Associates, Inc.
Consultants in Geotechnical Engineering
Geology and
NOT TO SCALE
Figure 1Date MAY 2024
VICINITY MAP
YELM, WASHINGTON
VISCONSI SR 507 RETAIL
Proj. No.T-8944
WALMART
TP-1B-1
TP-2
TP-3
TP-4
TP-7
TP-5
TP-6
B-2
B-3
SR 507SR 507
Environmental Earth Sciences
Terra Associates, Inc.
Consultants in Geotechnical Engineering
Geology and
Proj. No.T-8944
VISCONSI SR 507 RETAIL
YELM, WASHINGTON
EXPLORATION LOCATION PLAN
Date MAY 2024 Figure 2
REFERENCE:
LEGEND:
APPROXIMATE TEST PIT LOCATION
0 200 400
APPROXIMATE SCALE IN FEET
APPROXIMATE TEST BORING LOCATION
THURSTON COUNTY GEODATA CENTER
NOTE: THIS SITE PLAN IS SCHEMATIC.ALL LOCATIONS AND DIMENSIONS ARE APPROXIMATE. IT IS
INTENDED FOR REFERENCE ONLY AND SHOULD NOT BE USED FOR DESIGN OR CONSTRUCTION PURPOSES.
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Date and Time
Depth to Groundwater
Visconsi SR507 Retail
Yelm, Washington
B‐1 B‐3
Project T-8944
APPENDIX A
FIELD EXPLORATION AND LABORATORY TESTING
Visconsi SR 507 Retail
Yelm, Washington
We explored subsurface conditions at the site in seven test pits excavated to depths ranging from about 8 to 9 feet
below ground surface using a track-mounted excavator and in three test borings drilled to maximum depths ranging
between about 15 and 25 feet with a track-mounted drill rig using hollow-stem auger drilling methods. The test
pits and test boring locations were determined in the field using hand-held GPS positioning and by sighting relative
to existing surface features. The approximate test pit and test boring locations are shown on the attached Exploration
Location Plan, Figure 2. The test pit and test boring logs are attached as Figures A-2 through A-11. Monitoring
wells were constructed in the three borings subsequent to drilling and sampling. Each well is equipped with an
automated datalogger that is programmed to record groundwater levels at 1-hour intervals.
An engineering geologist from our office conducted the subsurface exploration. Our representative classified the
soil conditions encountered, maintained a log of each test boring, and collected representative soil samples. All soil
samples were visually classified in accordance with the Unified Soil Classification System (USCS) described on
Figure A-1.
Representative soil samples obtained from the test pits and test borings were placed in closed containers and taken
to our laboratory for further examination and testing. The moisture content of each sample was measured and is
reported on the respective log. Grain size analyses were performed on nine soil samples. The results are shown on
Figures A-12 through A-14.
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w
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Cl)
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w en w :::c 0 0
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0 �
MAJOR DIVISIONS
Clean
GRAVELS Gravels (less
than 5%More than 50%fines)of coarse fraction
is larger than No.
4 sieve Gravels with
fines
Clean Sands
SANDS (less than
More than 50% 5% fines)
of coarse fraction
is smaller than Sands withNo. 4 sieve fines
SIL TS AND CLAYS
Liquid Limit is less than 50%
SIL TS AND CLAYS
Liquid Limit is greater than 50%
HIGHLY ORGANIC SOILS
LETTER TYPICAL DESCRIPTIONSYMBOL
GW Well-graded gravels, gravel-sand mixtures, little or no fines.
GP Poorly-graded gravels, gravel-sand mixtures, little or no fines.
GM Silty gravels, gravel-sand-silt mixtures, non-plastic fines.
GC Clayey gravels, gravel-sand-clay mixtures, plastic fines.
SW Well-graded sands, sands with gravel, little or no fines.
SP Poorly-graded sands, sands with gravel, little or no fines.
SM Silty sands, sand-silt mixtures, non-plastic fines.
SC Clayey sands, sand-clay mixtures, plastic fines.
ML Inorganic silts, rock flour, clayey silts with slight plasticity.
CL Inorganic clays of low to medium plasticity. (Lean clay)
OL Organic silts and organic clays of low plasticity.
MH Inorganic silts, elastic.
CH Inorganic clays of high plasticity. (Fat clay)
OH Organic clays of high plasticity.
PT Peat.
DEFINITION OF TERMS AND SYMBOLS
Standard Penetration I 2" OUTSIDE DIAMETER SPILT SPOON SAMPLERDensityResistance in Blows/Foot
][ 2.4" INSIDE DIAMETER RING SAMPLER OR Very Loose 0-4 SHELBY TUBE SAMPLERLoose 4-10
Medium Dense 10-30 y WATER LEVEL (Da te)Dense 30-50
Very Dense >50 Tr TORVANE READINGS, tsf
Standard Penetration Pp PENETROMETER READING, tsf
Consistancy Resistance in Blows/Foot DD DRY DENSITY, pounds per cubic foot
Very Soft 0-2
Soft 2-4 LL LIQUID LIMIT, percent
Medium Stiff 4-8
Stiff 8-16 Pl PLASTIC INDEX
Very Stiff 16-32
Hard >32 N STANDARD PENETRATION, blows per foot
� Terra UNIFIED SOIL CLASSIFICATION SYSTEM VISCONSI SR 507 RETAIL �::: .. . Associates Inc. YELM, WASHINGTON
� Consultants in Geotechnical �nglneering Geology and Proj. No.T-8944 I Date MAY 2024 I Figure A-1Environmental Earth Sciences
15..
1-
LOG OF TEST PIT NO. 1
PROJECT NAME: Visconsi SR 507 Retail PROJ. NO: T-8944
LOCATION: Yelm, Washington SURFACE CONDITIONS: �G�ra=s�s�------
FIGUREA-2
LOGGED BY:_JC_S ___ _
APPROX. ELEV: '""'NA'-'----
DATE LOGGED: September 25, 2016 DEPTH TO GROUNDWATER: _NA _____ DEPTH TO CAVING:_N_A ____ _
a. Description
4 inches Sod and Topsoil.
Brown SAND with silt and gravel, fine sand, fine to coarse gravel, dry, scattered cobbles,
numerous fine roots. (SP-SM)
Consistency/
Relative Density
Medium Dense
2-1 Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (moist
below 5 feet), scattered cobbles, trace of 1-foot diameter boulders. (GP) 4.0
3-
4-
5-
6-
7-
8-
9-
10-
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
Loose to Medium
Dense
11 �-�---------------------------------_._ _____ __._----1
NOTE: This subsurface information pertains only to this test pit location and should not be interpreted as being indicative of other locations at the site.
LOG OF TEST PIT NO. 2
PROJECT NAME: Visconsi SR 507 Retail PROJ. NO: T-8944
LOCATION: Yelm. Washington SURFACE CONDITIONS: _G_ra_s_s ______ _
FIGUREA-3
LOGGED BY:.c...JC"-S"-----
APPROX. ELEV: _N_A __ _
DATE LOGGED: Septembe r 25, 2016 DEPTH TO GROUNDWATER: -'-'N�A'---____ DEPTH TO CAVING:"""'N�A'-------
OJ a. a. OJ
1-
2-
3-
4-
5-
6-1
7-
8-2
9-
10-
11 -
Desc ription
6 inches Sod and Topsoil.
Dark gray silty GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry,
\ scattered cobbles, numerous fine roots. (GM)
Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (moist
below 5 feet), numerous cobbles, scattered 1-to 2-foot diameter boulders. (GP)
Brown SAND to SAND with silt, fine to coarse sand, scattered fine to coarse gravel,
moist, scattered silty sand pockets and layers. (SP/SP-SM)
Test pit terminated at 10 feet.
No groundwater seepage.
Minor sloughing at variable depths.
Consistency/
Relative Density
Medium Dense
Loose to Medium
Dense
Medium Dense
3.0
18.6
12�-�---------------------------------�---------t
NOTE: This subsurface information pertains only to this test pit location and should not be interpreted as being indicative of other locations at the site.
10-
LOG OF TEST PIT NO. 3
PROJECT NAME: Visconsi SR Retail PROJ. NO: T-8944
LOCATION: Yelm, Washington SURFACE CONDITIONS: �G�ra=s�s ______ _
FIGUREA-4
LOGGED BY:_JC_S ___ _
APPROX. ELEV: '""'N�A __ _
DATE LOGGED: September DEPTH TO GROUNDWATER: .:....:cNA:....:.._ ____ DEPTH TO CAVING:_N_A ____ _
E
Description
4 inches Sod and Topsoil.
Dark gray silty SAND with gravel, fine sand, fine to coarse gravel, dry, scattered cobbles.
Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry,
numerous cobbles, trace of 1-foot diameter boulders. (GP)
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
Consistency/
Relative Density
Loose to Medium
Dense
Q)
0
1-
2-
3-
LOG OF TEST PIT NO. 4 FIGUREA-5
PROJECT NAME: Visconsi SR 507 Retail PROJ. NO: T-8944 LOGGED BY:_JC_S ___ _
LOCATION: Yelm, Washington SURFACE CONDITIONS: -=G'--'--ra=s=--'s'--------APPROX. ELEV: "'"'N ""'A __ _
DATE LOGGED: September 25, 2016 DEPTH TO GROUNDWATER: _NA _____ DEPTH TO CAVING:_N_A ____ _
Q) Description
4 inches Sod and Topsoil.
Dark gray silty SAND with gravel, fine sand, fine to coarse gravel, dry, scattered cobbles.
(SM)
Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (grades
dry to moist below 7 feet), numerous cobbles (grades to scattered cobbles below 6 feet),
trace of 1-foot diameter boulders. (GP)
Consistency/
Relative Density
4-1 3.4
5-
6-
7-
8-
9-
10-
11 -
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
Loose to Medium
Dense
12_.__.,__ _________________________________ ....._ _____ __. __
NOTE: This subsurface information pertains only to this test pit location and should not be interpreted as being indicative of other locations at the site.
0
1-
2-
3-
4-
5-
6-
7-
8-
9-
10-
11 -
LOG OF TEST PIT NO. 5 FIGUREA-6
PROJECT NAME: Visconsi SR 507 Retail PROJ. NO: T-8944 LOGGED BY:_JC_S ___ _
LOCATION:Yelm, Was hington SURFACE CONDITIONS:"""G"'"ra=s"""s'---------APPROX. ELEV: "'"'N'-'A __ _
DATE LOGGED: September 25, 2016 DEPTH TO GROUNDWATER: _NA _____ DEPTH TO CAVING:_N_A ____ _
Description
6 inches Sod and Topsoil.
Dark gray silty SAND with gravel, fine sand, fine to coarse gravel, dry, scattered cobbles.
(SM)
Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (grades
dry to moist below 7 feet), numerous cobbles (grades to scattered cobbles below 7 feet),
trace of 1-to 2-foot diameter boulders. (GP)
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
Con sistency/
Relative Density
Loose to Medium
Dense
12___.__.,__ _________________________________ _._ _____ _._ __
NOTE: This subsurface information pertains only to this test pit location and should not be interpreted as being indicative of other locations at the site.
LOG OF TEST PIT NO. 6 FIGUREA-7
PROJECT NAME: Visconsi SR 507 Retail PROJ. NO: T-8944 LOGGED BY: JCS
LOCATION:Yelm, Washington SURFACE CONDITIONS: Grass
APPROX. ELEV: NA
DATE LOGGED: September 25. 2016 DEPTH TO GROUNDWATER: NA DEPTH TO CAVING: NA
6
aZ Consistency/ o
a Description Relative Density
n E
a) -
01 v7
U
6 inches Sod and Topsoil.
1 Dark gray silty GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry,
scattered cobbles, trace of 1-foot diameter boulders, trace of plastic debris near ground
surface. (GM) (Possible fill/disturbed)
21 Gray -brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (moist
below 7 feet), numerous cobbles, scattered 1- to 1.5-foot diameter boulders. (GP)
7
L.1
er
10
- Decreasing proportions of coarse gravel, cobbles, and boulders below 7 feet.
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
NOTE: This subsurface information pertains only to this test pit location and should not be
interpreted as being indicative of other locations at the site.
Loose to Medium Dense I
Terra
koAssociates, Inc.
Consultants in Geotechnical Engineering
Ge=gy and
Environmental Earth Sciences
10-
LOG OF TEST PIT NO. 7 FIGUREA-8
PROJECT NAME: PROJ. NO: LOGGED
SURFACE CONDITIONS: APPROX.
DATE LOGGED: DEPTH TO GROUNDWATER: DEPTH TO CAVING:_N_A ____ _
6 inches Sod and Topsoil.
Dark gray silty SAND with gravel, fine sand, fine to coarse gravel, dry, scattered cobbles.
Gray-brown GRAVEL with sand, fine to coarse gravel, fine to coarse sand, dry (grades
dry to moist below 7 feet), numerous cobbles (grades to scattered cobbles below 7 feet),
trace of 1-to 2-foot diameter boulders. (GP)
Test pit terminated at 9 feet.
No groundwater seepage.
Minor sloughing at variable depths.
LOG OF BORING NO. 1
Project: Visconsi SR 507 Retail
Figure No. A-9
Project No: T-8944 __ Date Drilled: September 22, 2023
Client: Visconsi Companies, Ltd Driller: Boretec
Location: Yelm, Washington Depth to Groundwater:
m
i'
a�
� Soil Description
Consistency/
a Relative Density
Q E
o in
0 —r— 7
51T
- Drills gravelly with rig chatter.
Gray GRAVEL with sand, fine to coarse gravel, fine to
coarse sand, dry. (GP)
-----------------------------------------
Brown silty SAND with gravel, fine sand, fine to coarse
gravel, moist. (SM)
10
- Drills gravelly with rig chatter.
---------------------------------------
Gray-brown SAND with silt and gravel to GRAVEL with
silt and sand, fine sand, fine to coarse gravel, moist.
15 (SP-SM/GP-GM)
- Drills gravelly with rig chatter.
2011
25—� =
30
- Auger binding in gravel and cobbles below 20 feet.
- Drills gravelly with rig chatter.
---------- -....
Gray -brown SAND with silt and gravel to silty SAND
with gravel, fine to medium sand, fine to coarse gravel,
moist. (SP-SM/SM)
Boring terminated at 25.3 feet.
No groundwater encountered.
Installed 2-inch diameter PVC well to 25 feet.
(DOE Well ID - BPG 864)
Blow counts generally overstated due to coarse gravel
and cobbles.
Very Dense
Medium Dense
Dense
Very Dense
NOTE: This borehole log has been prepared for geotechnical purposes. This information
pertains only to this boring location and should not be interpeted as being indicative of
other areas of the site
Logged By: JCS
NA Approx. Elev. NA
SPT (N) Observ.
Blows / foot w Well
D C
10 30 50 2 U
52
0.6
11
4.2
•
37
5.1
—
50/6"
4.7
50/4"
5.7
Terra
Associates, Inc.
Consultants in Geotechnical Engineering
Geology and
Environmental Earth Sciences
LOG OF BORING NO. 2 Figure No. A-10
Project: Visconsi SR 507 Retail Project No: T-8944 Date Drilled: September 22. 2023
Client: Visconsi Companies, Ltd Driller: Boretec Logged By: _J_C_S___
Location: Yelm, Washington Depth to Groundwater: ----'N"""A-'--_ Approx. Elev: -'N"""A-'----
g
Q)
cii 2: Q)
Q) 0.. E (1l Cf)
Soil Description Consistency/ Relative Density
10
SPT (N) Blows /foot
30 50
��Q) -.._ C .a Q) oo·-C 0 0 �u
Observ. Well
o�-���n
-Drills gravelly with rig chatter.
10-I
15-I
-
20-
-
-
Gray GRAVEL with sand, fine to coarse gravel, fine sand, dry to moist. (GP)
-Drills gravelly with rig chatter.
Medium Dense
------------------------------------------------
Gray-brown SAND with gravel to SAND with silt and gravel, fine to medium sand, fine to coarse gravel, moist. (SP/SP-SM)
-Drills gravelly with rig chatter.Dense
----------------------------------------1--------1 Gray-brown SAND with silt and gravel to silty SAND with gravel, fine sand, fine to coarse gravel, moist. (SPSM/SM)
Boring terminated at 15.3 feet due to auger refusal. No groundwater encountered. Installed 2-inch diameter PVC well to 15 feet. (DOE Well ID -BNY 724) Blow counts generally overstated due to coarse gravel and cobbles.
Very Dense
• 11
• 43
•50/2"
2.5
5.3
3.5
I=
,,_ ,_ -
,-,,_ ,_ ,,_
--
25_,_ _ _._ ___________________ __,L.,_ ______ ..__.___,____. _ _.__._ __ _._ __ __,_ ___ ---I
NOTE: This borehole log has been prepared for geotechnical purposes. This information pertains only to this boring location and should not be interpeted as being indicative of other areas of the site
LOG OF BORING NO. 3 Figure No. A-11
Project: Visconsi SR 507 Retail Project No: T-8944 Date Drilled: September 22, 2023
Client: Visconsi Companies. Ltd Driller: Boretec Logged By: _J_C_S __ _
Location: Yelm, Washington Depth to Groundwater: __ N_A __ Approx. Elev: _N_A ___ _
g
Q)
5
10
15
cii 2:
Q)
Q) 0.. Eco(/)
I
I
I
Soil Description
-Drills gravelly with rig chatter.
Gray-brown silty SAND with gravel, fine sand, fine to
coarse gravel, dry. (SM)
-Drills gravelly with rig chatter.
---------------------------------------
Gray-brown SAND with silt and gravel, fine to medium
sand, fine to coarse gravel, moist. (SP-SM)
-Drills gravelly with rig chatter. Auger binding.
Consistency/
Relative Density
Very Dense
Dense
Medium Dense
10
SPT (N)
Blows / foot
30 50
•
•
58
46
28
��
Q) ..... .._ C .a Q) (/)+-' ·-C0 0 2 (.)
3.6
4.0
7.7
Observ.
Well
----------------------------------------------
20 I
25
30
Gray-brown silty SAND with gravel, fine to coarse
sand, fine to coarse gravel, moist. (SM)
-Very slow, gravelly drilling with rig chatter to 25 feet.
Auger binding. Unable to sample at 25 feet due to lead
auger loss.
Boring terminated at 25 feet due to auger break.
Sampled to 21.5 feet.
No groundwater encountered.
Installed 2-inch diameter PVC well to approximately 22
feet.
(DOE Well ID -BPG 865)
Blow counts generally overstated due to coarse gravel
and cobbles.
Dense
NOTE: This borehole log has been prepared for geotechnical purposes. This information pertains only to this boring location and should not be interpeted as being indicative of
other areas of the site
• 35 6.5
, Terra
•Associates, Inc.Consultants in Geotechnical Engineering Geology and Environmental Earth Sciences
Particle Size ❑istribution Report
r a o c
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GRAIN SIZE - mm.
% Gravel
% Sand
% Fines
% +3"
_
Coarse Medium Fine
Coarse Fine
Silt I Clay
01
0.0
17.4 34.3
6.9 26.0 10.8
4.6
❑
0.0
31.6 26.3
14.2 21.3 3.7
2.9
❑
0.0
0.0 0.0
0.2 47.9 1 39.4
12.5
LL
PL
Dili
Dan
Dsn
D
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DIO
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0
20.6812
9.1987
5.3977
0.6760
0.4176
0.2881
0.17
31.93
❑
28.3516
13.7071
7.5007
2.3066
0.7767
0.5643
0.69
24.29
❑
0.6933
0.4958
0.4010
0.1875
0.0983
Material Description
USCS
AASHTO
o GRAVEL with sand
GP
❑ GRAVEL with sand
GP
L silty SAND
SM
Project No. T-8944 Client: Visconsi Companies, Ltd
Remarks:
Project: Visconsi SR 507 Retail
oTested September 29, 2023
❑Tested September 29, 2023
o Location: TP-1 Depth: 2'
❑Tested September 29, 2023
Q Location: TP-2 Depth: 6'
❑ Location: TP-2 Depth: 8'
Terra Associates, Inc.
Kirkland _WA
Figure A-12
Tested By: KJ
Particle Size Distribution Report
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GRAIN SIZE - mm.
%D Gravel
%D Sand
%D Fines
%+3„
Coarse Fine
Coarse Medium I Fine
Silt Clay
0
0.0
27.7 32.1
10.3 21.6 5.3
3.0
❑
0.0
10.5 1 28.8
9.6 27.9 12.9
10.3
0
0.0
16.4 30.4
11.2 24.8 8.2
9.0
LL
PL
D
Dan
Dsp
D
DIS
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0
26.5747
12.9038
8.5096
2.0219
0.6267
0.4788
0.66
26.95
❑
15.4723
4.5262
1.7315
0.5686
0.1706
0
20.0916
7.4288
3.7433
1 0.8639
0.3198
0.1166
0.86
63.72
Material Description
USCS
AASHTO
o GRAVEL with sand
GP
o SAND with silt and gravel
SP-SM
,o GRAVEL with silt and sand
GP -GM
Project No. T-8944 Client: Visconsi Companies, Ltd
Remarks:
Project: Visconsi SR 507 Retail
oTested September 29, 2023
❑Tested September 29, 2023
o Location: TP-4 Depth: 4'
oTested September 29, 2023
❑ Location: B-1 Depth: 15'
A Location: B-1 Depth: 20'
Terra Associates, Inc.
Kirkland, WA
Figure A-13
Tested By: _ KJ
Appendix II
Existing Topography (by Crabtree Surveying LLC)
Appendix III
Stormwater Calculations and Basin Maps
Appendix IV
Source Control BMP’s
Automobile Washing
Most residents wash their cars in the driveway or on the street. Washwaters typically flow to a
storm drain or ditch, which discharges stormwater directly to the nearest river, stream, lake, or
Puget Sound. Soaps and detergents, even the biodegradable ones, can have immediate and
long-term effects on critters living in water bodies. The grime washed off the car also contains a
variety of pollutants that can harm fish and wildlife.
Suggested BMPs
Away from Home (preferred option):
• Consider not washing your car at home. Take it to a commercial car wash that has a recycle
system and discharges wastewater to the sanitary sewer for treatment.
At Home:
• Wash your car directly over your lawn or make sure the washwater drains to a vegetated area.
This allows the water and soap to soak into the ground instead of running off into a local water
body.
• Ideally, no soaps or detergents should be used, but if you do use one, select one without
phosphates.
• Commercial products are available that allow you to clean a vehicle without water. These were
developed for areas where water is scarce, so a water saving benefit is realized, as well as
reduced pollution.
• Use a hose nozzle with a shut-off valve to save water.
• Do not wash your car if rain is expected. Rain events will rapidly wash and chemicals and
cleaning products from your property into the stormwater system (and to downstream waters).
• Pour the bucket of soapy, dirty washwater down your sink. This way the water doesn’t pollute
surface water. Instead, it’s treated at the wastewater treatment plant.
Automobile Maintenance
Many of us are “weekend mechanics”. We enjoy the cost savings of changing our own oil and
antifreeze, topping off the battery with water, and generally making our car perform its best.
There is a lot of potential for stormwater pollution associated with these activities; however, the
following BMPs will help you minimize pollution while servicing your car.
Required BMPs
• Recycle all oils, antifreeze, solvents, and batteries. Many local car parts dealers and gas
stations accept used oil. The Household Hazardous Waste facilities at the Tacoma Landfill or
LRI Landfill accept oil, oil filters, antifreeze, and solvents. Thurston County and Tacoma also
hold Household Hazardous Waste turn-in days that will accept car wastes including old
batteries. Old batteries can actually be worth money. Search for local battery recycling
businesses to find out if any offer to buy used batteries. Use the numbers listed in Chapter 7
for more information.
• Never dump new or used automotive fluids or solvents on the ground, in a storm drain or street
gutter, or in a water body. Eventually, it will make its way to local surface waters or
groundwater, including the water we drink.
• Do not mix wastes. The chlorinated solvents in some carburetor cleaners can contaminate a
huge tank of used oil, rendering it unsuitable for recycling. Always keep your wastes in
separate containers which are properly labeled and store them out of the weather.
Suggested BMPs
• Fix all leaks, to keep the leaky material off streets and out of surface water.
• To dispose of oil filters, punch a hole in the top and let drain for 24 hours. This is where a large
funnel in the top of your oil storage container will come in handy. After draining, wrap in 2
layers of plastic and dispose of in your regular garbage or recycle by taking it to the Tacoma
Landfill or LRI Landfill Household Hazardous Waste facility for Tacoma residents and non-
residents. Call the Hazardous Waste line at 1-800-287-6429 for up-to-date information on the
appropriate disposal of consumer products.
• Use care in draining and collecting antifreeze to prevent accidental spills. Spilled antifreeze
can be deadly to cats and dogs that ingest it.
• Perform your service activities on concrete or asphalt or over a plastic tarpaulin to make spill
cleanup easier. Keep a bag of kitty litter on hand to absorb spills. If there is a spill, sprinkle a
good layer on the spill, let it absorb for a little while and then sweep it up. Place the
contaminated litter in a plastic bag, tie it up, and dispose of it in your regular garbage. Take
care not to leave kitty litter out in the rain; it will form sticky goo that is hard to clean up.
• If you are doing body work outside, be sure to use a tarpaulin to catch material resulting from
grinding, sanding, and painting. Dispose of this waste by double bagging in plastic and placing
in your garbage.
Storage of Solid Wastes and Yard Wastes
Improper storage of recycling, yard waste, and trash at residences can lead not only to water
pollution problems, but problems with neighborhood pets and vermin as well.
Following the BMPs listed below can help keep your property a clean and healthy place to live.
Suggested BMPs
All recycling and waste containers kept outside should have lids (Figure 3.1). If your lid is
damaged, you should repair or replace it as soon as possible. If your container is supplied by
your hauler, please call to have the lid repaired or replaced. Find your hauler’s contact
information at: https://thurston.lemayinc.com/services/residential/residential-recycling
• Leaking containers should be replaced. If your container is supplied by your hauler, contact
the hauler to have damaged containers replaced.
• Store containers under cover if possible, or on grassy areas.
• Inspect the storage area regularly to pick up loose scraps of material and dispose of them
properly.
• Tips for reducing waste:
o Recycle as much as you can. Some Thurston County residents have access to curbside
pickup for yard waste and recyclable materials. Use the online recycling menu to find more
recycling options: https://thurston.lemayinc.com/services/residential/residential-recycling
o Purchase products which have the least amount of packaging materials.
o Compost biodegradable materials such as grass clippings and vegetable scraps instead of
throwing them away. Your flowerbeds will love the finished compost, and you’ll be helping to
conserve limited landfill space. See the section on composting for BMPs relating to that
activity.
o A fun alternative to traditional composting is worm composting. You can let worms do all the
work for you by keeping a small vermiculture box just outside your kitchen.
Composting
Composting is an earth-friendly activity as long as some common-sense rules outlined below
are followed. If you choose to compost, the following BMPs should be utilized.
Suggested BMPs
• Compost piles must be located on an unpaved area where runoff can soak into the ground or
be filtered by grass and other vegetation. Compost piles should be located in an area of your
yard not prone to water ponding during storms, and should be kept well away from wetlands,
streams, lakes, and other drainage paths.
• Compost piles must be maintained and turned over regularly to work properly. Large piles of
unattended compost may create odor and vermin problems.
• Cover the compost pile for two reasons:
1. To keep stormwater from washing nutrients into waterways.
2. To keep excess water from cooling down the pile, which will slow down the rate of
decomposition.
Build Bins of wood, chicken wire, or fencing material to contain compost so it can't be washed
away.
Building a small earthen dike around your compost pile is an effective means of preventing
nutrient-rich compost drainage from reaching stormwater paths.
Yard Maintenance and Gardening
This section deals with the normal yard maintenance activities we all perform at our homes.
Overwatering, overfertilizing, improper herbicide application, and improper disposal of trimmings
and clippings can all contribute to serious water pollution problems. Following the BMPs listed
below will help alleviate pollutant runoff.
Required BMPs
Follow the manufacturer's directions exactly for mixing and applying herbicides, fungicides, and
pesticides, and use them sparingly. Never apply when it is windy or when rain is expected.
Never apply over water, within 100 feet of a well-head, or adjacent to streams, wetlands, or
other water bodies. Triple-rinse empty containers, using the rinse for mixing your next batch of
spray, and then double-bag and dispose of the empty container in your regular garbage. Never
dispose of grass clippings or other vegetation in or near storm drains, streams, lakes, or Puget
Sound.
Suggested BMPs
• Use natural, organic soil amendments like Thurston County’s SoundGRO Mix. SoundGRO
Mix is a 100 percent recycled blend of dewatered, Class A, “Exceptional Quality” biosolids,
mixed with sawdust and sand. The excellent soil conditioning properties of the organic matter
aid water retention in lighter soils and help to break up and aerate heavier soils, so roots can
grow better and less watering is needed. It contains both readily available and long-term
nitrogen and other nutrients commonly lacking in Northwest soils.
The slow release of nitrogen better matches the needs of plants. Thus, there is much less
potential for nitrates to leach into surface or groundwater due both to less “excess nitrogen”
and less water use. Better vegetative growth can also reduce erosion and runoff.
• Follow manufacturer's directions when applying fertilizers. More is not better, either for your
lawn or for local water bodies. Never apply fertilizers over water or adjacent to ditches,
streams, or other water bodies. Remember that organic fertilizers have a slow release of
nitrogen, and less potential to pollute then synthetic fertilizers.
• Save water and prevent pollution problems by watering your lawn sensibly. Lawns and
gardens typically need the equivalent of 1 inch of rainfall per week. You can check on how
you're doing by putting a wide mouth jar out where you're sprinkling and measure the water
with a small plastic ruler. Overwatering to the point of runoff can carry polluting nutrients to the
nearest water body.
• Consider planting a vegetated buffer zone adjacent to streams or other water bodies on your
property. Call the Thurston County Conservation District at (253) 845-9770 for advice and
assistance in developing a planting plan. The Stream Team at the Conservation District may
even be able to help you plant it!
• Reduce the need for pesticides and fertilizers on lawns by improving the health of the soil.
Aerating, thatching, and topdressing with compost or the City of Tacoma’s Tagro products will
improve soil health and help wanted grasses compete with weeds and moss.
• Make sure all fertilizers and pesticides are stored in a covered location. Rain can wash the
labels off of bottles and convert 50 pounds of fertilizer into either a solid lump or a river of
nutrients.
• Use a mulching mower and mow higher to improve soil/grass health and reduce or eliminate
pesticide use.
• Compost all yard clippings or use them as mulch to save water and keep down weeds in your
garden.
• Practice organic gardening and virtually eliminate the need to use pesticides and fertilizers.
• Pull weeds instead of spraying and get some healthy exercise, too. If you must spray, use the
least toxic formulations that will get the job done.
• Work fertilizers into the soil instead of letting them lie on the ground surface exposed to the
next rain storm.
• Plant native vegetation which is suited to Northwest conditions, they require less water and
little to no fertilizers and pesticides.
• Contact your local waste disposal company for curbside pickup and recycling of yard waste.
Household Hazardous Material Use, Storage, and Disposal
Once we really start looking around our houses, the amount of hazardous materials we have
onsite is a real eye-opener. Oil-based paints and stains, paint thinner, gasoline, charcoal starter
fluid, cleaners, waxes, pesticides, fingernail polish remover, and wood preservatives are just a
few hazardous materials that most of us have around the house.
When products such as these are dumped on the ground or in a storm drain, they can be
washed directly to receiving waters where they can harm fish and wildlife. They can also
infiltrate into the ground and contaminate drinking water supplies. The same problem can occur
if they are disposed of with your regular garbage; the containers can leak at the landfill and
contaminate groundwater. The same type of contamination can also occur if hazardous
products are poured down a sink or toilet into a septic system. Don't pour them down the drain if
you're on municipal sewers, either. Many compounds can “pass through” the wastewater
treatment plant without treatment and contaminate receiving waters, or they can harm the
biological process used at the treatment plant, reducing overall treatment efficiency.
With such a diversity of hazardous products present in all homes in Thurston County, a large
potential for serious environmental harm exists if improper methods of storage, usage, and
disposal are employed. Using the following BMPs will help keep these materials out of our soils,
sediments, and waters.
Required BMPs
• Hazardous Materials must be used in accordance with the manufacturer recommendation or
guidelines as shown on the label.
• Always store hazardous materials in properly labeled containers, never in food or beverage
containers which could be misinterpreted by a child as something to eat or drink.
• Dispose of hazardous materials and their containers properly. Never dump products labeled
as poisonous, corrosive, caustic, flammable, inflammable, volatile, explosive danger, warning,
caution, or dangerous outdoors, in a storm drain, or into sinks, toilets or drains. Visit the
Hazardous Waste Web page at https://www.thurstoncountywa.gov/departments/public-
works/solid-waste/garbage-recycling/household-hazardous-waste , for information on disposal
methods, collection events, and alternative products. Household hazardous wastes from
Thurston County residents and non-residents are accepted at HazoHouse Drop-off at 2420
Hogum Bay Road NE, Lacey, WA 98516.
Suggested BMPs
• Check hazardous material containers frequently for signs of leakage. If a container is rusty
and has the potential of leaking soon, place it in a secondary container before the leak occurs
and prevent a cleanup problem.
• Hazardous materials should be stored out of the reach of children.
• Store hazardous materials containers under cover and off the ground. Keep them out of the
weather to avoid rusting, freezing, cracking, labels being washed off, etc.
• Keep appropriate spill cleanup materials on hand. Kitty litter is good for many oil-based spills.
• Ground cloths and drip pans must be used under any work outdoors which involves
hazardous materials such as oil-based paints, stains, rust removers, masonry cleaners, and
others bearing label warnings as outlined above.
Repair and Maintenance
• Latex paints are not a hazardous waste, but are not accepted in liquid form at the landfill. To
dispose of, leave uncovered in a protected place until dry, then place in the garbage. If you
wish to dry waste paint quickly, mix kitty litter or sawdust in the can to absorb the paint. Once
paint is dry, leave the lid off when you place it in the garbage so your garbage collector can
see that it is no longer liquid.
• Use less toxic products whenever possible. The Hazardous Waste Line at 1-800-287-6429
and the Washington Toxics Coalition at (206) 632-1545 have information detailing alternatives
to toxic products.
• If an activity involving the use of a hazardous material can be moved indoors out of the
weather, then do so. Make sure you can provide proper ventilation, however.
• Follow manufacturers' directions in the use of all materials. Over-application of yard
chemicals, for instance, can result in the washing of these compounds into receiving water
bodies. Never apply pesticides when rain is expected.
• When hazardous materials are in use, place the container inside a tub or bucket to minimize
spills and store materials above the local base flood elevation (BFE).
Pet Waste Management
Pet waste that washes into rivers, lakes, streams or Puget Sound begins to decay, using up
oxygen and releasing ammonia. Low oxygen levels and ammonia combined with warm water
can kill fish. Pet waste also contains nutrients that encourage weed and algae growth in waters
we use for swimming, boating and fishing. Most importantly, pet waste can carry diseases and
bacteria that could make water unsafe for contact and lead to beach closures or effect shellfish
harvest. These include:
• Campylobacteriosis—bacterial infection
• Salmonellosis—bacterial infection
• Toxocariasis—roundworm infection
• Toxoplasmosis—protozoan parasite infection
• Giardiasis—protozoan parasite infection
• Fecal Coliform—bacteria in feces, indicates contamination
• E. coli—bacteria in feces, may cause disease.
Cleaning up after your pet can be as simple as taking a plastic bag or pooper scooper along on
your next walk. Then choose one of the following:
Suggested BMPs
• Bag it – Put waste in a securely closed bag and deposit it in the trash. Do not put it in
your yard waste container because pet waste may carry diseases, and yard waste
treatment may not kill disease organisms.
• Bury it – Bury waste at least 1 foot deep and cover with soil in your yard or garden
(not in food-growing areas).
• Flush it – Only flush pet wastes if your home is served by a sanitary sewer which
goes to a sewage treatment plant. Water from your toilet goes through a treatment
process that removes pollutants before it is discharged into the environment. To
prevent plumbing problems, don’t flush debris or cat litter. Cat feces may be flushed, but used
litter should be put in a securely closed bag in the trash. Septic systems are not designed to
accommodate the high pollutant load of pet waste. To prevent premature failure or excessive
maintenance costs do not flush pet wastes to your septic system.
• Compost it – waste from small animals other than dogs and cats (rabbits, rodents, etc.),
can be put in your compost bin.