Geotech Report.pdf- - _'_ - N GA
Main Office
17311— 1351 Ave NE, A-500
Woodinville, WA 98072
(425) 486-1669 • FAX (425) 481-2510
April 1, 2019
Mr. David Muresan
P.O. Box 3285
Bellevue, WA 98009
dbmuresan(a gmail.com
NELSON GEOTECHNICAL
ASSOCIATES, INC.
GEOTECHNICAL ENGINEERS & GEOLOGISTS
Geotechnical Engineering Evaluation - Revised
Muresan 3-Lot Short Plat
15809 — 70th Avenue West
Edmonds, Washington
NGA File No. 10487B 19
Dear Mr. Muresan:
Engineering -Geology Branch
55261ndustry Lane, #2
East Wenatchee, WA 98802
(509) 665-7696 • FAX (509) 665-7692
RECEIVE[
AUG 012019
OEVELOCOUN SERVICES
We are pleased to submit the attached report titled "Geotechnical Engineering Evaluation - Revised —
Muresan 3-Lot ShortPlat —15809 - 70'" Avenue West —Edmonds, Washington." This report summarizes
the existing surface and subsurface conditions related to the slope in the backyard area of the site and
provides recommendations for risk mitigation of slope movement. Our services were completed in general
accordance with the proposal signed by you on February 21, 2019.
The property is currently developed with a single-family residence and a detached shed. The ground surface
includes moderate topographic relief with moderate to steep slopes. Specific grading plans were not
available at the time this report was prepared; however, we understand that the proposed development will
separate the lot into three separate lots with additions to the existing residence on one of the lots, and two
new residences constructed on the remaining lots of the short plat.
We initially completed four test pit explorations, two hand auger explorations, and a small-scale pilot
infiltration test (PIT) within the property to investigate subsurface soil and groundwater conditions.
Recently, we revisited the site to investigate infiltration feasibility within proximity to the proposed
facilities with two additional test pits, five additional hand auger explorations, and another infiltration PIT.
Our explorations verified that the site was underlain by surficial topsoil or undocumented fill throughout
the site with competent, native glacial soils at relatively shallow depths.
It is our opinion that the planned development is feasible from a geotechnical standpoint, provided that our
recommendations are incorporated into the design and construction of this project. Foundations should be
advanced through any loose soils down to the competent glacial material interpreted to underlie the site, for
bearing capacity and settlement considerations. Specifically, the report includes general recommendations
for earthwork, temporary shoring, slabs -on -grade, structural fill placement, erosion control, and drainage.
We should be retained to review and comment on final development plans, provide recommendations for
design changes should the conditions revealed differ from those anticipated, and to evaluate whether or not
earthwork and foundation installation activities comply with contract plans and specifications.
Geotechnical Engineering Evaluation - Revised
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Summary - Page 2
We appreciate the opportunity to provide service to you on this project. Please contact us if you have any
questions regarding this report or require f irther information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Khaled M. Shawish, PE
Principal
TABLE OF CONTENTS
PROJECTDESCRIPTION.............................................................................................1
SCOPE...............................................................................................................................1
GEOLOGICALOVERVIEW......................................................................................... 2
SURFACECONDITIONS............................................................................................... 2
SUBSURFACECONDITIONS.......................................................................................
3
Hydrogeology...............................................................................................................
4
LaboratoryAnalyses....................................................................................................
4
CRITICALAREAS EVALUATION..............................................................................
4
SeismicHazard.............................................................................................................
4
ErosionHazard.............................................................................................................
5
LandslideHazard..........................................................................................................
5
CONCLUSIONS AND RECOMMENDATIONS.......................................................... 6
Erosion Control and Slope Protection Measures
......................................................... 6
SitePreparation and Grading.......................................................................................
6
Temporary and Permanent Slopes...............................................................................
7
FoundationSupport ......................................................................................................
8
RetainingWalls...........................................................................................................
9
StructuralFill..............................................................................................................
10
Utilities.......................................................................................................................
11
Slab-on-Grade............................................................................................................
11
Pavements...................................................................................................................
11
InfiltrationTesting......................................................................................................
11
SiteDrainage..............................................................................................................
13
USEOF THIS REPORT................................................................................................ 14
List of FijZures
Figure 1— Vicinity Map
Figure 2 — Site Plan
Figure 3 — Cross -Section A -A'
Figure 4 — Cross -Section B-B'
Figure 5 — Soil Classification Chart
Figures 6 through 9 — Log of Explorations
Figures 10 and 11— Grain Size Sieve Analyses
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation - Revised
Muresan 3-Lot Short Plat
15809 — 70th Avenue West
Edmonds, Washington
INTRODUCTION
This report presents the results of our geotechnical engineering investigation and evaluation of the proposed
Mot Residential Short Plat in Edmonds, Washington. The project site is located at 15809 — 70t' Avenue
West, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize
the site's surface and subsurface conditions and to provide geotechnical recommendations for the planned
site development.
Presently, an existing single-family home with an underground basement level and detached shed building
occupy the eastern -half of the property, but it has been proposed to subdivide the property into three separate
lots (Lots 1, 2, and 3) as a part of a new short -plat development. The existing house on the property is to
remain on Lot 2, and new developments will include two single-family residences to occupy each of the
other two subdivided lots (Lots 1 and 3). Also, it is our understanding that the owner intends to build an
addition/remodel on the north side of the house.
SCOPE
The purpose of this study was to explore and characterize the site subsurface conditions, and provide our
opinions and recommendations for geotechnical aspects of the proposed development. Specifically, our
scope of services included the following:
Geological Reconnaissance: Performed field reconnaissance of the site to assess existing soil
conditions and other site conditions.
Subsurface Investigation: Investigated subsurface conditions with test pits dug using a track -hoe.
Soil conditions encountered during the subsurface investigation were documented and soil samples
collected for the purpose of developing soils logs.
Infiltration Testing: Per City of Edmond's Appendix B — Methods for Determining Design
Infiltration Rates, infiltration testing is required when glacially consolidated (e.g. Vashon till or
advance outwash) are present at the site near the surface. NGA performed two single small-scale
pilot infiltration test (PIT) at locations of proposed infiltration facilities, as well as additional
laboratory grain size analyses on samples collected from explorations.
Slope Evaluation: Performed visual field reconnaissance of slope on subject property and shallow
hand -excavations to characterize soil conditions on the slope. Evaluated slope qualitatively based
on visual field observations and available geologic and topographical data.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 2
• Critical Area Review: Evaluated the geological hazards on the property (including landslide and
erosion hazards) based on available topographical and geological information. Provided
classification of geological hazards per City of Edmonds standards.
• Geotechnical Analysis: Performed engineering analysis and developed engineering
recommendations for geotechnical aspects of the proposed development including foundations,
slab -on -grade floors, earthwork, and subsurface drainage.
• Geotechnical Report: Prepared a report that presents findings, conclusions, and recommendations
developed during our study. The report included a site plan which identifies the test pit locations,
soils logs for each test pit, and other illustrations as appropriate.
GEOLOGICAL OVERVIEW
The Geologic map of the Edmonds East and part of the Edmonds Wcst quadrangles Washington (MF-
1541), by James P. Minard, (USGS, 1983) was reviewed for this site. This geologic map indicates the
location of the subject property is underlain by either Quaternary Vashon till (Qvt) or Quaternary advance
outwash deposits (Qva). Vashon till typically consists of a concrete -like mixture of relatively equal parts
of silt, sand, and gravel, while advance outwash generally comprises mostly clean, gray, pebbly sand. Both
of these materials were deposited by glaciers during the last glaciation period roughly 13,000 to 15,000
years ago. Because both of these materials were glacially overridden, they are typically dense in their native,
undisturbed condition, making them a favorable material to support building foundations.
In addition to geological maps, the USDA's online Web Soil Survey tool was utilized to identify the
weathered surficial soils expected to be present at the site overlying native, in -situ soils mentioned
previously. According to this resource, Alderwood-Urban Land Complex (5) is expected to be present at
the property at the surface. Alderwood-Urban Land Complex generally is a moderately well -drained soil
composed of gravelly sandy loam or gravelly ashy sandy loam (60% content similar to Alderwood soils),
generally formed on till plains with 2 to 8 percent slopes by weathering of underlying glacial soil.
SURFACE CONDITIONS
The property is bordered by 70'h Avenue West in the west, and by residential properties on all other sides.
Topographically, properties to the south is situated with approximately 10 to 15 feet of vertical relief above
the subject parcel. Associated north -facing slopes on the southern portion of the subject property step down
at moderate to steep gradients up to 26 degrees (49 percent grade). The rest of the property slopes gently to
moderately to the west toward 70' Avenue West with gradients up to 21 degrees (38 percent), as shown on
Cross Sections A -A' and B-B' in Figures 3 and 4, respectively.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 3
A distinct and separate hill forms a second -order topographical feature in the southwest portion of the
property adjacent to 70th Ave W. The hill comprises an east -facing slope of 20 degrees and a west -facing
slope of 16 degrees, as shown on Cross Section A -A' in Figure 3.
In terms of vegetation, much of the property is forested with mature -growth trees, including douglas fir,
cedar, hemlock, as well as younger madrona species. Some of the plants that constitute the understory
growth in the forested parts of the property include ivy, laurel, salal, Oregon -grape, evergreen huckleberry,
and sword ferns. The sloped areas of the property are considered moderately to well -vegetated, whereas
grass -lawn areas occupy some of the flatter portions of the property, specifically surrounding the existing
house and also adjoining to either side of the existing driveway near the property.
SUBSURFACE CONDITIONS
The subsurface conditions within the site were initially investigated on July 13th, 2018 by excavating a
total of five explorations with a track -hoe excavator. Follow up explorations were completed on March 7,
2019 with three additional test pits and five additional hand auger explorations. The approximate locations
of the explorations are shown on the Schematic Site Plan in Figure 2. Staff from Nelson Geotechnical
Associates, Inc. (NGA) conducted the explorations, collected samples of the soils encountered, and
maintained a log of the explorations.
The soils were visually classified in general accordance with the Unified Soil Classification System,
presented as Figure 5. The logs of the explorations are presented in Figures 6 through 9. We present a brief
summary of the subsurface conditions in the paragraph below. For a detailed description of the subsurface
conditions, the exploration logs should be reviewed.
Explorations in the west -central portion of the site encountered a surficial layer of mixed soils which we
interpreted as undocumented fill, the thickness of which was unconstrained by Test Pits 101 and 201, as
well as Hand Auger 201. These explorations were terminated at depths of 6.0, 9.0, and 6.0 feet, respectively.
The lateral extent of the undocumented fill on the site is shown on the Site Plan in Figure 2. Beneath the
undocumented fill in all explorations, we encountered gray or brownish gray clean sands with varying
amounts of gravel. These sandy soils are reasonably consistent with the description of advance outwash,
which was previously mapped on this site.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 4
Hydrogeology
Groundwater seepage was not encountered in any of our explorations. However, if groundwater were to be
encountered on this site, we would interpret it to be perched groundwater. Perched groundwater seepage
occurs when the water infiltrates through less dense, more permeable soils and accumulates on the top of
underlying, less permeable soils, but is not considered representative of the regional groundwater "table"
within the upper soil horizons. Perched water tends to vary spatially and is dependent on the amount of
precipitation. It also tends to flow laterally above the impermeable layer and may daylight on slopes in the
form of seasonal seepage.
Laboratory Analyses
We performed two grain size sieve analyses on samples collected from the explorations. Samples processed
in sieve analyses include those taken from Hand Auger 202 at a depth of 4.0 feet and from Hand Auger 205
at a depth of 2.3 feet below the existing ground surface. The soils tested are classified on the USDA textural
triangle as sand. The results of the sieve analyses are presented as Figures 10 and 11.
CRITICAL AREAS EVALUATION
The following subsections present assessment of geologic hazards, including seismic, erosion, and landslide
hazards.
Seismic Hazard: We reviewed the 2018 International Building Code (IBC) for seismic site classification
for this project. Based on sites with similar geology and findings from the subsurface investigation, the
soils at the site best fit the IBC description for Site Class D. The USGS design maps online application was
utilized to determine parameters for seismic design, which are provided below:
Table 1: 2018 IBC Seismic Design Parameters
Site Class
Spectral
Spectral Acceleration
Site Coefficients
Design Spectral
Acceleration at 0.2
at 1.0 sec. (g)
Response
sec. (g)
S1
Parameters
Fa
F„
SDs
SM
&
r_D_
1.325
0.521
1.000
1.500
0.883
0.521
Hazards associated with seismic activity include liquefaction potential and amplification of ground motion.
Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater
table. Because a groundwater table was not found to present near the ground surface and also because the
relative density of soils interpreted to underlie the site is predominately medium dense or better (below
weathered or disturbed surface soils), it is our opinion that the risk of liquefaction and amplification of
ground motion is low. Likewise, given the geology and our evaluation of the subsurface conditions, NGA
considers the risk of seismically -induced deep-seated failures occurring on the slope to be minimal.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotecluucal Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B19
April 1, 2019
Page 5
Erosion Hazard: The criteria used for determining the erosion hazard for the site soils includes soil type,
slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative
cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil
Survey of Sruohoruuish County Area, Washingtont by the Natural Resources Conservation Service (MRCS)
was reviewed to determine the erosion hazard of the on -site soils. The site surface soils were classified
using the NRCS classification system as Alderwood-Urban Land Complex gravelly sandy loam. These soils
are listed as having a moderate hazard of water erosion. It is our opinion that these soils should have a slight
to low hazard for erosion in areas that are not disturbed and where the vegetation cover is not removed.
Surficial erosion is a natural process and was observed on the steeper slopes at the time of our visit.
Landslide Hazard/Slope Stability: Based on our field investigation, the slopes at the site described in the
Surface Conditions section of this report appeared to be in a stable condition. No signs of significant
movement were observed on the slope (e.g. leaning trees, scarps, etc.), nor signs of shallow emergent
groundwater near the surface. The soils at the surface of slope (shallower than 2-feet below existing grade)
were in a loose condition, but this is to be expected and the vegetation observed on the slope should help
stabilize these soils. Below these looser soils, the soils became progressively denser with depth and
achieved a medium dense state at 2-feet below ground surface and a dense condition at 3-feet below existing
grade based on results from subsurface investigation.
The landslide hazard potential of the slopes on the property was also evaluated with respect to landslide
hazard definitions delineated by Edmonds City Code (ECC). Based on our review, the slopes on the subj ect
property do not meet the criteria for landslide hazards as defined by ECC Chapter 23.80.020(B)(4).
Although some of the slopes exceed 40 percent in slope grade, they neither maintain this grade for a
horizontal distance of greater than 25-feet, nor a vertical rise of at least 10-feet. A topographical survey was
not available at the time of preparing this report, so this conclusion was based on slope mapping and rough
measurements taken during our field visits.
The core of the site slopes are inferred to consist primarily of dense or better native glacial soils. Relatively
shallow sloughing failures as well as surficial erosion are natural processes and should be expected on the
steeper site slopes during extreme weather conditions. It is our opinion that while there is potential for
erosion, soil creep, and shallow failures within the loose surficial and or undocumented fill soils on the
steeper site slopes, there is not significant potential for deep-seated slope failures under current site
conditions. We anticipate that the proposed site grading will likely reduce the existing site grades and
slopes as a part of the proposed development. Proper site grading and drainage as well as adequate
foundation placement as recommended in this report should help maintain current stability conditions.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
CONCLUSIONS AND RECOMMENDATIONS
NGA File No. 10487B 19
April 1, 2019
Page 6
It is our opinion that the proposed development on the subject property is feasible from a geotechnical
standpoint, provided that the recommendations in this report are incorporated into the design and
construction of this project. The following subsections present the conclusions and recommendations
developed during our geotechnical engineering study based on our field investigation of the site.
Erosion Control and Slope Protection Measures
The erosion hazard for the on -site soils is listed as very severe throughout the property, but the actual hazard
will depend on how the site is graded and how water is managed. Best Management Practices (BMPs)
should be used to control erosion. Areas disturbed during construction should be protected from erosion.
Erosion control measures may include diverting surface water away from stripped or disturbed areas and
not allowing water to concentrate and flow uncontrolled. Silt fences and/or straw bales should be erected
to prevent muddy water from leaving the site or flowing toward the steep slope. Stockpiles should be
covered with plastic sheeting during wet weather. Disturbed areas should be planted as soon as practical
and the vegetation should be maintained until it is established. Replacement of vegetation should be
performed in accordance with City of Edmonds guidelines. The erosion potential for areas not stripped of
vegetation should be slight to low.
We recommend that the site development activities be concentrated on the benches, and that steep slopes
be disturbed as little as practical, for long-term stability of the slope. No material of any kind should be
placed on the steep slopes, or be allowed to reach them, such as excavation spoils, lawn clippings and other
yard waste, trash, and soil stockpiles. Any proposed future development should be reviewed by NGA for
the need to conduct a specific geotechnical evaluation, as needed. Under no circumstances should water be
allowed to concentrate or allowed to flow on the steep slopes. The slopes should be monitored during wet
weather and corrective measures promptly implemented should any signs of slope distress or instability be
observed.
Site Preparation and Grading
After initial erosion control measures are implemented, site preparation should consist of stripping areas to
be developed of all organic matter, organic -laden topsoil, and soil with abundant roots. Some of the stripped
materials may be stockpiled for later reuse in landscaped areas; excess materials should be removed and
disposed of offsite. This layer is approximately one -foot thick across the entire site.
We recommend that areas that are at grade, or will be supporting fill, foundations, concrete slabs, or
pavements be scarified to a depth of at least 12 inches (after stripping) to identify buried roots or any
unsuitable materials and to create more uniform conditions. Roots and other unsuitable materials should be
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 7
removed and the scarified soils should be moisture -conditioned as needed and recompacted to the
requirements of structural fill described below.
The timing of earthwork with respect to seasonal variations in the environment will have some effect on
the behavior of the native onsite soils. The amount of silt in the soil indicates that the soils are somewhat
moisture sensitive and may be difficult to compact if they are overly wet. We recommend that construction
take place during the drier summer and early autumn months, if possible. If construction takes place during
the rainy season, additional expenses and delays should be expected due to overly wet conditions.
Temporary and Permanent Slopes
Temporary excavation stability is a function of many factors, including the type and consistency of soils,
depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the
presence of surface water or groundwater. It is exceedingly difficult under these variable conditions to
estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to
maintain safe slope configurations since they are continuously at the job site, able to observe the soil and
groundwater conditions encountered, and able to monitor the nature and condition of the cut slopes.
The following information is provided solely for the benefit of the owner and other design consultants and
should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job
site safety. Job site safety is the sole responsibility of the project contractor.
For planning purposes, we recommend that all temporary cuts be no steeper than 2 Horizontal to 1 Vertical
(2H: IV). If groundwater seepage is encountered, we expect that flatter inclinations may be necessary. We
recommend that cut slopes be protected from erosion. Measures taken may include covering cut slopes with
plastic sheeting and diverting surface runoff away from the top of cut slopes. Excavated material should
not be stockpiled any closer than 10 feet from the top of the cuts. We do not recommend vertical slopes for
cuts deeper than 4 feet if worker access is necessary. We recommend that cut slope heights and inclinations
conform to WISHA/OSHA standards.
The contractor should be responsible for the implementation of safe cut slope since, they are regularly
present at the site to observe site conditions. If the above inclinations cannot be met due to site constraints
and/or worker access issues, we recommend that shoring be considered for temporary cuts. We are available
to provide specific recommendations for temporary shoring once the foundation design has been finalized.
Permanent cut and fill slopes should be no steeper than 2H:1V. Permanent slopes should be planted and
the vegetative cover should be maintained until it is established. We should review plans for this project
and visit the site to evaluate any excavations that are deeper than about 4 feet. If constraints limit safe cut
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation NGA File No. 10487B 19
Muresan 3-Lot Short Plat April 1, 2019
Edmonds, Washington Page 8
or fill slopes, retaining walls may be required. NGA is available to provide retaining wall recommendations
when needed.
Foundation Support
Conventional shallow spread foundations should be placed on medium dense or better native soils, or be
supported on structural fill or rock spalls extending to those soils. Based on our explorations, medium
dense soils are anticipated to be present at depths less than approximately 3 feet below ground surface.
If less dense soils are encountered at the footing bearing elevation, the subgrade should be over -excavated
to expose suitable bearing soil. The over -excavation may be filled with structural fill, or the footing may
be extended down to the competent native soils. If footings are supported on structural fill, the fill zone
should extend outside the edges of the footing a distance equal to one half of the depth of the over -
excavation below the bottom of the footing.
Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost
protection and bearing capacity considerations. Foundations should be designed in accordance with the
2018 IBC. Footing widths should be based on the anticipated loads and allowable soil bearing pressure.
Water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be
removed from the foundation excavation prior to placing concrete.
For foundations constructed as outlined above, we recommend an allowable design bearing pressure of not
more than 2,000 pounds per square foot (psf) be used for the design of footings founded on the medium
dense or better native soils or structural fill extending to the competent native material. The structural fill
should extend a minimum distance of half the depth of the footing on both sides of the footing. The
foundation bearing soil should be evaluated by a representative of NGA, and we should be consulted if
higher bearing pressures are needed. Current IBC guidelines should be used when considering increased
allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation settlement
using the recommended allowable bearing pressure is estimated to be less than 1 inch total and '/z-inch
differential between adjacent footings or across a distance of about 20 feet, based on our experience with
similar projects. Downhill footings should be embedded into the native bearing soil a minimum of 3.5 feet
below lowest adjacent fmished ground surface.
Lateral loads may be resisted by friction on the base of the footing and passive resistance against the
subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base
friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a
triangular equivalent fluid pressure distribution. An equivalent fluid density of 200 pounds per cubic foot
(pcf) should be used for passive resistance design for a level ground surface adjacent to the footing. This
level surface should extend a distance equal to at least three times the footing depth. These recommended
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 104871319
April 1, 2019
Page 9
values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and
passive resistance, respectively. To achieve this value of passive resistance, the foundations should be
poured "neat" against the native medium dense soils or structural fill should be used to backfill against the
front of the footing. We recommend that the upper 1 foot of soil be neglected when calculating the passive
resistance.
Retaining Walls
Specific grading plans for this project were not available at the time this report was prepared, but we
anticipate that retaining walls may be incorporated into project plans for the proposed residence basement.
In general, the lateral pressure acting on subsurface retaining walls is dependent on the nature and density
of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall
drainage conditions, and the inclination of the backfill. For walls that are free to yield at the top at least
one thousandth of the height of the wall (active condition), soil pressures will be less than if movement is
limited by such factors as wall stiffness or bracing (at -rest condition). We recommend that walls supporting
horizontal backfill and not subjected to hydrostatic forces, be designed using a triangular earth pressure
distribution equivalent to that exerted by a fluid with a density of 40 pcf for yielding (active condition)
walls, and 60 pcf for non -yielding (at -rest condition) walls. A seismic design loading of 8H in psf should
also be included in the wall design where "H" is the total height of the wall.
These recommended lateral earth pressures are for a drained granular backfill and are based on the
assumption of a horizontal ground surface behind the wall for a distance of at least the subsurface height of
the wall, and do not account for surcharge loads. Additional lateral earth pressures should be considered
for surcharge loads acting adjacent to subsurface walls and within a distance equal to the subsurface height
of the wall. This would include the effects of surcharges such as traffic loads, floor slab loads, slopes, or
other surface loads. We could consult with the structural engineer regarding additional loads on retaining
walls during final design, if needed.
The lateral pressures on walls may be resisted by friction between the foundation and subgrade soil, and by
passive resistance acting on the below -grade portion of the foundation. Recommendations for frictional
and passive resistance to lateral loads are presented in the Foundations subsection of this report.
All wall backfill should be well compacted as outlined in the Structural Fill subsection of this report. Care
should be taken to prevent the buildup of excess lateral soil pressures due to over -compaction of the wall
backfill. This can be accomplished by placing wall backfill in 8-inch loose lifts and compacting the backfill
with small, hand -operated compactors within a distance behind the wall equal to at least one-half the height
of the wall. The thickness of the loose lifts should be reduced to accommodate the lower compactive energy
of the hand -operated equipment. The recommended level of compaction should still be maintained.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation NGA File No. 10487B 19
Muresan 3-Lot Short Plat April 1, 2019
Edmonds, Washington Page 10
Permanent drainage systems should be installed for retaining walls. Recommendations for these systems
are found in the Subsurface Drainage subsection of this report. We recommend that we be retained to
evaluate the proposed wall drain backfill material and observe installation of the drainage systems.
Structural Fill
Fill placed beneath foundations, concrete slabs, pavement, or other settlement -sensitive structures should
be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods
and standards, and is monitored by an experienced geotechnical professional or soils technician. Field
monitoring procedures would include the performance of a representative number of in -place density tests
to document the attainment of the desired degree of relative compaction. The area to receive the fill should
be suitably prepared as described in the Site Preparation and Grading subsection of this report prior to
beginning fill placement. Fill placed on slopes should be a minimum of 8-foot wide benches keyed into
slopes.
Materials: Structural fill should consist of a good quality, granular soil, free of organics and other
deleterious material, and be well graded to a maximum size of about 3 inches. All-weather structural fill
should contain no more than 5 percent fines (soil finer than U.S. No. 200 sieve, based on that fraction
passing the U.S. 3/4-inch sieve). The use of on -site soils as structural fill should be feasible, but will be
dependent on moisture content of the material at the time construction takes place. We should be retained
to evaluate proposed structural fill material prior to placement.
Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All fill
placements should be accomplished in uniform lifts up to 8 inches thick. Each lift should be spread evenly
and be thoroughly compacted prior to placement of subsequent lifts.
All structural fill underlying building areas, concrete floor slabs, and pavement subgrade should be
compacted to a minimum of 95 percent of its maximum dry density. Maximum dry density in this report
refers to that density as determined by the ASTM D-1557 Compaction Test (Modified Proctor) procedure.
The moisture content of the soils to be compacted should be within about f 2 percent of optimum so that a
readily compactable condition exists. It may be necessary to over -excavate and remove wet soils where
drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of
a type and size sufficient to attain the desired degree of compaction.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 11
Utilities
We recommend that underground utilities be bedded with a minimum 6 inches of pea gravel prior to
backfilling the trench with on -site or imported material. Trenches within settlement sensitive areas should
be compacted to 95% of the modified proctor as described in the Structural Fill subsection of this report
and should be tested. Trenches located in non-structural areas should be compacted to a minimum 90% of
the maximum dry density. Trench backfill compaction should be tested.
Slab -on -Grade
Slabs -on -grade should be supported on subgrade soils prepared as described in the Site Preparation and
Grading subsection of this letter. We recommend that all floor slabs be underlain by at least six inches of
free -draining gravel with less than 3 percent by weight of the material passing the U.S. No. 200 Sieve for
use as a capillary break. We recommend that the capillary break be hydraulically connected to the footing
drain system to allow free drainage from under the slab. A suitable vapor barrier, such as heavy plastic
sheeting (6-mil minimum), should be placed over the capillary break material. An additional 2-inch-thick
moist sand layer may be used to cover the vapor barrier. This sand layer may be used to protect the vapor
barrier membrane and to aid in curing the concrete.
Pavements
Pavement (including gravel -surfacing) subgrade preparation and structural filling where required, should
be completed as recommended in the Site Preparation and Grading and Structural Fill subsections of
this letter. Pavement subgrade should be proof -rolled with a heavy, rubber -tired piece of equipment, to
identify soft or yielding areas that require repair.
Infiltration Testing
Infiltration PIT 101: We conducted a Small PIT within the southwestern portion of the site on July 13,
2018, located as shown on the attached Schematic Site Plan in Figure 2. The test was conducted within the
sandy soils which we interpreted as native advance outwash in an excavation that measured 3.0-feet long
by 5.0-feet wide by 4.0-feet deep. The pit was filled with 12-inches of water at the beginning of the day and
we began the soaking period of the PIT for approximately 6 hours. At this time, the water flow rate into
the hole was monitored with a Great Plains Industries (GPI) TM 075 water flow meter for the pre-soak
period.
After the 6-hour soaking period was completed, the water level was maintained at approximately 12-inches
for one hour during the steady-state period. During the steady-state period, the flow rate stabilized at 2.50
gallons per minute (150 gallons per hour), corresponding to an infiltration rate of 16.04 inches per hour.
The water was then shut off and the level monitored for the falling head period. After 51 minutes, the water
level within the pit completely dissipated, resulting in a measured infiltration rate of 14.1 inches per hour.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 12
Infiltration PIT 201: We conducted a Small PIT within the upper, southeastern portion of the site on
March 7, 2019, located as shown on the attached Schematic Site Plan in Figure 2. The test was conducted
within the near -surface weathered soils in an excavation that measured 4.0-feet long by 3.0-feet wide by
4.5-feet deep. The pit was filled with 12-inches of water at the beginning of the day and we began the
soaking period of the PIT for approximately 6 hours. At this time, the water flow rate into the hole was
monitored with a Great Plains Industries (GPI) TM 075 water flow meter for the pre-soak period.
After the 6-hour soaking period was completed, the water level was maintained at approximately 12-inches
for one hour during the steady-state period. During the steady-state period, the flow rate stabilized at 2.31
gallons per minute (139 gallons per hour), corresponding to an infiltration rate of 18.53 inches per hour.
The water was then shut off and the level monitored for the falling head period. After approximately 60
minutes, the water level within the pit completely dissipated, resulting in a measured infiltration rate of 12.0
inches per hour.
Long -Term Design Rate: In accordance with the Table III-3.3.1 of the 2014 SWMMWW, correction
factors of 0.9, 0.5, and 0.9 for CFv, CFt, CFm, respectively were applied to the most conservative field
measured infiltration rate of 12.0 inches per hour, obtained from the falling -head portion of the testing in
Infiltration Pit 201. A total correction factor of 0.405 was applied to the measured field infiltration rates
obtained from the falling head portion of the test to determine the long-term design infiltration rates.
Using the above correction factor, we calculated a long-term design infiltration rate of approximately 4.86
inches per hour within the granular native soils. In our opinion, this long-term design infiltration rate could
be utilized to design infiltration systems within the native deposits found on this site at respective depths.
It is our opinion that the subsurface soils within the site are suitable for traditional stormwater infiltration
systems. The subsurface soils generally consisted of surficial undoctunented fill soils underlain by fine to
medium sand with gravel that we interpreted as native glacial outwash deposits. No groundwater seepage
was encountered in our explorations within the site. We recommend that the base of any on -site infiltration
systems be terminated within the native materials found at depth within the site. We recommend these
systems be sized and designed in accordance with the 2014 Stormwatcr Management Manual for Western
Washington and in conjunction with the provided long-term design infiltration rates provided above. Siltier
soils would not support these infiltration rate, and as such, it is imperative that cleaner sands and gravels be
exposed at the bottom of these infiltration systems and that no restrictive layers are found within three feet
below bottom of infiltration systems. We should be retained during construction to evaluate the soils
exposed in the infiltration locations to confirm that the soils are appropriate for infiltration.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 13
We recommend that any proposed infiltration systems be placed as to not negatively impact any proposed
or existing nearby structures and also meet all required setbacks from existing property lines, structures,
and sensitive areas as discussed in the drainage manual. Under no circumstances should water be directed
toward or allowed to flow freely over the steep slopes on the western portion of the property. In general,
infiltration systems should not be located within proposed fill areas within the site, associated with site
grading or retaining wall backfill as such condition could lead to failures of the placed fills and/or retaining
structures. We should be retained to evaluate the infiltration system design and installation during
construction.
Site Drainage
The subsections below present recommendations for surface and subsurface drainage at the site.
Surface Drainage: Final site grades should allow for drainage away from site slopes and away from the
planned residence areas. We suggest that the finished ground be sloped at a minimum gradient of three
percent for a distance of at least 10 feet away from the building. Runoff generated on this site should be
collected and routed into a permanent discharge system. This should include all downspouts and runoff
generated on all hard surfaces and yards areas. Under no circumstances should water be allowed to flow
uncontrolled over slopes. Water should not be allowed to collect in any area where footings or slabs are to
be constructed.
Subsurface Drainage: If groundwater is encountered during construction, we recommend that the
contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where
the water can be pumped from the excavation and routed to an approved discharge point. Water should not
be allowed to flow over the steep slopes.
We recommend the use of footing drains around structures. Footing drains should be installed at least 1
foot below planned finished floor elevation. The drains should consist of a minimum 4-inch-diameter, rigid,
slotted or perforated, PVC pipe surrounded by free -draining material wrapped in a filter fabric. Footing
drains should discharge into tightlines leading to an approved collection and discharge point away from the
slope, with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected
to wall or footing drains.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Muresan 3-Lot Short Plat
Edmonds, Washington
USE OF THIS REPORT
NGA File No. 10487B 19
April 1, 2019
Page 14
NGA has prepared this report for Mr. David Muresan and his agents, for use in the planning and design of
the new classroom on this site only. The geotechnical evaluations presented in this report are specific to
the planned location of the new classroom and should not be considered an evaluation of the entire site.
There is potential for shallow failures to continue to occur on the slope. This potential can be reduced by
maintaining the drainage systems and refraining from disposing of any material onto or near the slope.
Irrigation systems near the slopes should be avoided.
The scope of our work does not include services related to construction safety precautions, and our
recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures,
except as specifically described in our letter for consideration in design. There are possible variations in
subsurface conditions between the explored and unexplored areas and also with time. Our letter,
conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A
contingency for unanticipated conditions should be included in the budget and schedule.
It should be noted that all buildings that exist near slopes are at risk for landslide movements. The property
owner should periodically inspect the slope, especially after experiencing severe inclement weather. If
distress is evident, a geotechnical engineer should be contacted for advice on remedial/preventative
measures. The probability that landsliding will occur is substantially reduced by the proper maintenance
of drainage control measures at the site (the runoff from the roofs should be led to an approved discharge
point). Therefore, the property owner should take responsibility for performing such maintenance.
Consequently, we recommend that a copy of our report be provided to any future homeowners of the
properties if the homes are sold.
We recommend that NGA be retained to review project plans prior to construction and to monitor activities
during construction. These additional services are intended to confirm that the conditions encountered are
consistent with those indicated by the explorations, to provide recommendations for design changes should
the actual site conditions differ from those anticipated, and to evaluate whether or not construction activities
comply with specifications. We should be contacted a minimum of one week prior to construction activities
and could attend pre -construction meetings if requested.
Within the limitations of scope, schedule and budget, our services have been performed in accordance with
generally accepted geotechnical engineering practices in effect in this area at the time this letter was
prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are
a means to identify and reduce the inherent risks to the owner.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechuical Engineering Evaluation
Muresan 3-Lot Short Plat
Ediuonds, Washington
NGA File No. 10487B 19
April 1, 2019
Page 15
It has been a pleasure to provide service to you on this project. If you have any questions or require further
information, please feel free to contact us.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Carston T. Curd, GIT
Staff Geologist H
Maher A. Shebl, PhD, PE, M.ASCE
Senior Engineer
CTC:MAS:dy
Eleven Figures Attached
NELSON GEOTECHNICAL ASSOCIATES, INC.
VICINITY MAP
Not to Scale
NIT AD0WDALE
-k
0
a�
a
�o
n
166th PI S'N
Project
Site
Meadowdale
Bea0i Park
N
l
1
IOIL•S'•
76�"h SI S1Y
1'•i:� "�I S71
r
3
16501 PI S'J1
Meadowdale
`l
Playflelds
`'
9
z
a
I
Meadowdale
1681h St SW
w
Middle School
Meadowdale High School
z
�
9
Q
C
,
1
�
Edmonds, WA
Project Number
10487B19
Muresan 3-Lot
Short Plat
NELSON GEOTECHNICAL
ASSOCIATES INC.
N�'� '
GEOTECHNICAL ENGINEERS & GEOLOGISTS
NO.
Date
Revision
By
CK o
r
1
3/12/19
Original
DPN
CTC
F
Figure 1
Vicinity Map
Woodinville Office Beat Wenatchee Orrice
Ave. NE,
a
17311.135th A-500 $526 Industry Lem, N2
WA
J
J
Woodinville, 95072 Eaal Wenatchee, WA 55602
(i25)e56-1659/ Fa.:451d510 v .nelsangeotachwm (509)665-7696IF-665-7692
=
o.
-n o m
cQ -i' 0
v Z
W C:
N 3
Approximate Extent of
Undocumented Fill
Proposed Residence
s�'Z
a.a o
s� m
n G) Proposed Residence —
-zo Z D
x g In
Z
z yr
Z mo
m O z
m n
3 a Y m
-i O
m -1
r:^-m (n n
boa= O
p — • Property line
N r
I N F-201
J i K I _L- OI-71 --T -
LEGEND
o Number and approximate location
N v I of infiltration test pit (3-7-19)
TP-201
Number and approximate
I location of test pit (3-7-19)
u c HA-201
Number and approximate
Z ° I location of hand auger (3-7-19)
01
o Rafaranna• Cite nian hascxi nn a ninn dateri nt-remher T
INF-101
Number and approximate location
I
of infiltration test pit (7-13-18)
TP-101
Number and approximate
I
location of test pit (7-13-18)
HA-101
Number and approximate
I
location of hand auger (7-13-18)
MI-- 9-- \A........... Ci....+ 0I-f ^ —--- 1nd h
0
oo, Existing House
Proposed Shed
0 50 100
Scale: 1 inch = 50 feet
�5
c
C)
o N
� v
v v
w
m r-
0 o
o C/)
v =r
D0
D�
v
West
120,
aD
c
60
n
> 70th Ave W 21 °
o Z W
D z �' � r 16° 24 26 HA-102
H 0 1 u � m Q 30
N r TP-103
M O Z
3 a A
-� O
O umi M 0-
Existing
SheI
2 71
A'
a
` Jn0 z Z
0
0 30 60 90 120 150 180 210 240
�os1 >
y r
Distance (feet)
Exploration
v
o a'
m Test Pit / Hand Auger Designation DTP-1 / HA-1
0
East
r 120
M
.r
30
0
d U Groundwater Level V NOTES:
0 During Exploration 1) Stratigraphic conditions are interpolated between
the explorations. Actual conditions may vary.
o v Geologic Contact ?— — —? 2) Elevations are arbitrary.
(approximate) _
Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure.
MdAcomoanv\P018 NGA Project FO:ders\10487-18 3-Lot Short Plat - David MuresanlDrafunalCS.dwp
0 a
o C/)
v =T
00 0
00 �
v
West
120,
.0
i
60
c�
Existing ►� ��--
Driveway
c, >
N n Z w 70th Ave W
1'
$10 16,
z M 21 ° LA-204
Ng0 HA-101
° � Z Q 30
M
m N o TP-101
m O Z
3 N a R
o
Existing
Driveway
3
a
No _n
r9g Z z 1 1 I 1 I I 1 I I 1 1 I I I 1 t 1 1 1 I 1 1 I 1 1 1 t 1 I I I 1
>o�' 0 0 30 60 90 120 150 180 210 240
m3 a
In r
Distance (feet)
Exploration
v
o :v
m Test Pit / Hand Auger Designation DTP-1 / HA-1
o �
m
East
120
.A
30
M
Groundwater Level NOTES:
5 During Exploration 1) Stratigraphic conditions are interpolated between
the explorations. Actual conditions may vary.
o co Geologic Contact 2) Elevations are arbitrary.
z (approximate)
� Reference: Cross Section is based on field measurements using a hand-held clinometer and 100-ft tape measure.
"hitlleNf2A P-i—I I: JrIc VInAR7_1Q'U N Chr ! Plat - 1`12-d IdvaeaMnntnirxtl('C rfun
UNIFIED SOIL CLASSIFICATION SYSTEM
GROUP
MAJOR DIVISIONS
GROUP NAME
SYMBOL
CLEAN
GW
WELL -GRADED, FINE TO COARSE GRAVEL
COARSE- GRAVEL
GRAVEL
GP
POORLY -GRADED GRAVEL
GRAINED MORE THAN 50 % GRAVEL
GM
SILTY GRAVEL
OF COARSE FRACTION
RETAINED ON
SOILS NO.4 SIEVE WITH FINES
GC
CLAYEY GRAVEL
SAND
CLEAN
SW
WELL -GRADED SAND, FINE TO COARSE SAND
SAND
SP
POORLY GRADED SAND
MORE THAN 50 %
MORE THAN 50 %
RETAINED ON
OF COARSE FRACTION
SAND
SM
SILTY SAND
NO.200 SIEVE
PASSES NO.4 SIEVE
SC
CLAYEY SAND
WITH FINES
FINE -
SILT AND CLAY
ML
SILT
INORGANIC
CL
CLAY
GRAINED
LIQUID LIMIT
LESS THAN 50 %
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SOILS
SILT AND CLAY
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
INORGANIC
MORE THAN 50 %
g
PASSES
CH
CLAY OF HIGH PLASTICITY, FAT CLAY
LIQUID LIMIT
N0.200 SIEVE
50 % OR MORE
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
9
E
HIGHLY ORGANIC SOILS PT PEAT
LL
Z
NOTES:
is
0
1) Field classification is based on visual SOIL MOISTURE MODIFIERS:
a
examination of soil in general
Dry - Absence of moisture, dusty, dry to
7
accordance with ASTM D 2488-93.
the touch
2
a
2) Soil classification using laboratory tests
Moist -Damp, but no visible water.
m
is based on ASTM D 2488-93.
0
Wet -Visible free water or saturated,
3) Descriptions of soil density or usually soil is obtained from
LL
consistency are based on
y below water table
interpretation of blowcount data,
visual appearance of soils, and/or
a
test data.
Project Number
NELSON GEOTECHNICAL
No.
Date
Revision
By
CK
o
Muresan 3-Lot
ASSOCIATES, INC.
NGA
DPN
CTC
10487B19
Short Plat
GEOTECHNICAL ENGINEERS & GEOLOGISTS
1
3/15/19
Oginal
8
Figure 5
Soil Classification Chart
M.
W1351h Ave. oFA Emt W�n�tchn ,#2
17WooOI w: ch.:
J
I',I WAl612°° Ent WA 99902
(425)�96.1659/ fu'.401•2510 N.minaq�d.cn Ccm (:09)f6575i5 rF.. L5S7u92
=
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
TEST PIT 101
0.0 - 2.0 DARK BROWN SILTY FINE TO COARSE SAND WITH ORGANIC PARTICULATE (LOOSE, MOIST)
(TOPSOIL)
2.0-5.0 BROWN -GRAY FINE TO COARSE SAND WITH GRAVEL (LOOSE -MEDIUM DENSE, DRY)
(UNDOCUMENTED FILL)
5.0 - 6.0 GRAY SILTY FINE TO COARSE SAND WITH GRAVEL (DENSE, DRY)
(GLACIAL TILL -DERIVED UNDOCUMENTED FILL)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS TERMINATED AT 6.0 FEET ON 7/13/2018
TEST PIT 102
0.0 - 2.0
DARK BROWN SILTY FINE TO COARSE SAND WITH ORGANIC PARTICULATE (LOOSE, MOIST)
(TOPSOIL)
2.0 - 3.0
SP-SM
GRAY -BROWN FINE TO COARSE SAND WITH GRAVEL AND TRACE SILT
(LOOSE -MEDIUM DENSE, DRY)
3.0 - 9.0
SP
GRAY FINE TO MEDIUM SAND WITH TRACE GRAVEL (MEDIUM DENSE, DRY)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 9.0 FEET ON 7/13/2018
TEST PIT 103
0.0 - 2.0
SP-SM
GRAY -BROWN FINE TO COARSE SAND WITH GRAVEL AND TRACE SILT
(LOOSE -MEDIUM DENSE, MOIST)
2.0 - 5.0
GP
GRAY FINE TO MEDIUM SANDY GRAVEL (MEDIUM DENSE -DENSE, DRY)
5.0 - 9.0
SP
GRAY FINE TO MEDIUM SAND WITH GRAVEL (DENSE, DRY)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 9.0 FEET ON 7/13/2018
TEST PIT 104
0.0 - 4.0 SP-SM YELLOW -BROWN FINE TO COARSE SAND WITH GRAVEL AND TRACE SILT
(LOOSE -MEDIUM DENSE, DRY)
4.0-5.5 SP-SM GRAY FINE TO MEDIUM SANDY GRAVEL WITH TRACE SILT AND ORGANIC DEBRIS,
INCLUDING TREE ROOTS (LOOSE, DRY)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS TERMINATED AT 5.5 FEET ON 7/13/2018
ABR:DCC:CTC NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 104871319
FIGURE 6
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
TEST PIT 201
0.0 -4.0 DARK BROWN TO BROWN, FINE TO MEDIUM SAND WITH SILT, ORAGNICS, ROOTS, GRAVEL,
AND TRACE METAL SCRAPS (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL)
4.0 - 6.0 GRAY -BROWN TO REDDISH BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS,
AND ORGANICS (MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL)
6.0-9.0 LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, GRAVEL, AND ROOTS
(LOOSE TO MEDIUM DENSE, DRY) (UNDOCUMENTED FILL)
SAMPLE WAS COLLECTED AT 9.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 9.0 FEET ON 3/7/2019
TEST PIT 202
0.0-0.8 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH ROOTS, GRAVEL, AND ORGANICS
(LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL)
0.8 - 3.5 SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT, TRACE ROOTS, AND GRAVEL
(MEDIUM DENSE, MOIST)
3.5 - 6.0 SP-SM GRAY, FINE TO COARSE SAND WITH SILT AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED AT 2.0 AND 6.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 6.0 FEET ON 3/7/2019
INFILTRATION PIT 101
0.0-0.8
DARK BROWN TO BROWN, ORGANIC -RICH SILTY FINE TO MEDIUM SAND WITH GRAVEL,
ROOTS, AND ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL)
8.8 - 6.0
SP-SM LIGHT BROWN TO GRAY -BROWN, FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(MEDIUM DENSE TO DENSE, MOIST)
6.0 - 8.0
SP-SM GRAY, FINE TO COARSE SAND WITH SILT AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST)
SAMPLES WERE COLLECTED AT 5.0 AND 7.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 8.0 FEET ON 3/8/2019
INFILTRATION PIT 201
0.0 - 2.0
SP-SM LIGHT BROWN TO GRAY -BROWN FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(LOOSE -MEDIUM DENSE, MOIST) (TOPSOIL)
2.0 - 4.0
SP GRAY, FINE TO COARSE SAND WITH GRAVEL (MEDIUM DENSE -DENSE, MOIST)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 4.0 FEET ON 7/13/2018
HAND AUGER 101
0.0-3.0 SP-SM DARK GRAY -BROWN FINE TO MEDIUM SAND WITH GRAVEL AND TRACE SILT (LOOSE -
MEDIUM DENSE, DRY)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER MET REFUSAL AT 3.0 FEET ON 7/13/2018
ABR:DCC:CTC NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 10487619
FIGURE 7
LOG OF EXPLORATION
DEPTH (FEET)
USC SOIL DESCRIPTION
HAND AUGER 102
0.0 - 3.0
SP-SM YELLOW -BROWN FINE TO MEDIUM SAND WITH TRACE GRAVEL AND SILT
(LOOSE -MEDIUM DENSE, MOIST)
NO SAMPLES WERE COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER MET REFUSAL AT 3.0 FEET ON 7/13/2018
HAND AUGER 201
0.0 - 3.0
FOREST FLOOR DEBRIS UNDERLAIN BY GRAY, FINE TO COARSE SAND WITH SILT,
ORGANICS, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL)
3.0-6.0
DARK BROWN TO BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ORGANICS, AND
WOOD DEBRIS (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL)
SAMPLE WAS NOT COLLECTED
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER MET REFUSAL AT 6.0 FEET ON 3/7/2019
HAND AUGER 202
0.0 -2.0
FOREST FLOOR DEBRIS UNDERLAIN BY DARK BROWN TO BROWN, SILTY FINE TO MEDIUM
SAND WITH GRAVEL, ORGANICS, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST)
(UNDOCUMENTED FILL)
2.0 - 5.0
SP-SM BROWN TO LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED AT 4.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER WAS COMPLETED AT 5.0 FEET ON 3/7/2019
HAND AUGER 203
0.0 - 3.0
FOREST FLOOR DEBRIS UNDERLAIN BY DARK BROWN TO REDDISH BROWN, SILTY FINE TO
MEDIUM SAND WITH GRAVEL, ORGANICS, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST)
(UNDOCUMENTED FILL)
3.0 - 5.0
SP-SM GRAY, FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED AT 4.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER WAS COMPLETED AT 5.0 FEET ON 3/7/2019
HAND AUGER 204
0.0 - 0.8 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ORGANICS, AND ROOTS
(LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL)
0.8 - 3.5 SP-SM LIGHT BROWN, FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED AT 3.5 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER MET REFUSAL AT 3.5 FEET ON 3/7/2019
ABR:DCC:CTC NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 104871319
FIGURE 8
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
HAND AUGER 205
0.0-0.9 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ORGANICS, AND ROOTS
(LOOSE TO MEDIUM DENSE, MOIST) (TOPSOIL)
0.9 - 5.0 SP-SM LIGHT BROWN TO GRAY -BROWN, FINE TO MEDIUM SAND WITH SILT AND GRAVEL
(MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED AT 2.3 AND 5.0 FEET
GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED
HAND AUGER CAVING WAS NOT ENCOUNTERED
HAND AUGER MET REFUSAL AT 5.0 FEET ON 3/7/2019
ABR:DCC:CTC NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 10487619
FIGURE 9
o
T!
� Cl)
U.S. STANDARD SIEVE SIZE
0
o
(0
m
100
90
v? K
80
CID C v
m Zor CCD
\
>
70
Cn
0
m60
I
z
50
m
=oaf
w
40
Z
MO
\
T>=
w
i
z y
30
a
M
m
20
Z a
_ N U)
oZ
m
10
m n
I
I
I
3 Am
' 1 0
0
Ip
"r " = 0 m m
1000
100 10 1.0 0.1
0.01 0.001
P g. o z Z
GRAIN SIZE IN MILLIMETERS
0
a:1 a
0
`=
v
m
o
m
m
s
v
�
N
0
o
Z
IX0
COBBLES
GRAVEL
SAND
SILT OR CLAY
U.S.C.
EXPLORATION
SAMPLE
SOIL
SYMBOL
NUMBER
DEPTH
SOIL DESCRIPTION
DISTRIBUTION
Fine to medium sand with silt and trace
Gravel = 11%
•SP-SM
HA-202
4.0 feet
gravel
Sand = 78%
Silt/Clay = 11
Slulllccmpany12019 NGA Pro!eC FohlersV 47876-19 Muresan Additional IN EdmontlslDreltirtg�,Sieve.dwg
� 0
U.S. STANDARD SIEVE SIZE
m
W
I `�''
co Cr
m
100
90
v?
CD
Cn
80
CDD
F-
>
70
v w
w
%< H
Cn' o
60
m
I
I
I
I
z
I
I
I
50
:o DMZ
w40
30
a
>=
>Z
IL
m
20
z y r
ka
\.
M o Z
10
m n
I
I
I
3 aM
m n
11000
100
10 1.0 0.1
0.01 0.001
o z z
GRAIN SIZE IN MILLIMETERS
n
r
GRAVEL
SAND
U.S.C.
EXPLORATION
SAMPLE
SOIL
SYMBOL
NUMBER
DEPTH
SOIL DESCRIPTION
DISTRIBUTION
Fine to medium sand with silt and trace
Gravel = 12%
•SP-SM
HA-205
2.3 feet
gravel
Sand = 81
Silt/Clay = 7%