Geotech Report Mar '07- 234 Edmonds 022818.pdfGary A. Flowers, PLLC
Geological & Geotechnieal Consulting
19532 12`11 Avenue NE
Shoreline, WA "155-1106
October 11, 2007
Revised March 18, 2007
Project No. 07-076 CITY COPY ilel�
�V13
Mr. Patrick Morris MAR ? 0 2008
MorDevCo, LLC 8U11-oiNG D
P.O. Box 60152 C17y. OF ED�AMMEW
Seattle, Washington 98160-0152
Subject: Subsurface Exploration and Geotechnical Engineering Report
Edmonds Commercial Development
NW Quadrant of 234ei St SW & Hwy 99
Edmonds, Washington
Dear Mr. Morris:
We have completed subsurface explorations and geologic/geotechnical engineering evaluations
at the "Edmonds Commercial Development" project site at the above noted location in Edmonds,
Washington. This report summarizes our findings, and presents information regarding
subsurface conditions and geotechnical engineering design recommendations for planning and
design of this project.
The project site is located on the west side of Hwy 99 (Aurora Ave N) just north of 230 Street
SW in the southeast portion of the town of Edmonds. Development plans indicate that three
retail buildings will be constructed on the site in the approximate locations shown on Figure 1,
Site and Exploration Plan. Associated parking lots and driveway will also be constructed as
shown. We understand that, at present, site grading details have not been finalized. However,
preliminary plans indicate that only minor grading will be required to accommodate building
sites, roads, and storm detention and utility construction.
The purpose of our site evaluation was to characterize shallow soil and ground water conditions
on the property, and to provide geotechnical engineering design recommendations for planning
and construction of the proposed development. The scope of our work included; 1) a review of
provided development plans, 2) research of geologic and soils mapping information in our files,
3) exploration of site soils conditions using small, client provided, backhoe, 4) perform geologic
and geotechnical engineering evaluations, and 4) preparation of this report. Our field
explorations were conducted on July 30, 2007.
Gary A. Planers, PLLC.
19532 12" Avenge NE Shoreline, washinginn "I55.1106
E C L U
JUL J 2008
EECE
7-7640
Proposed Edmonds Retail Development Geolol;tcati(;eotec,iiiiical Services Report
234'h St, SW (4,, Nwy99. Edmonds, Washington
EXISTING SITE CONDITONS
The subject property is shaped like a truncated triangle with the base to the north and the apex to
the south. It is bounded on the south by 2340' Street SW, on the east by Hwy 99, on the north by
a storage yard and on the west by an apartment complex.
The site slopes gently downward to the east. Most of the grade change occurs on the western
two-thirds of the site while the area along Hwy 99 is relatively level. Based on hand
measurements only, total elevation change across the site is on the order of 18 feet. The site is
about 2 to 3 feet higher in elevation than the sidewalk along the east side. No steep slopes exist
within or adjacent to the property other than a 4 to b foot berm or slope along the west property
line on the southern portion of the site. Due to very heavy vegetative cover in this area the actual
slope was difficult to observe.
Vegetation on the property consists of a stand of evergreen trees in the northwest portion of the
site, a row of tall bushes and deciduous trees along the westem property line, blackberry bushes
in the northeast portion of the site and field grass with some bramble bushes over the remainder
of the parcel. The lower, eastern portion of the site had been recently mowed.
There was no indication of standing or flowing water on the site at the time of our field work:.
No areas of erosion were observed anywhere on the site.
SUBSURFACE CONDITIONS
Explorations
Our field explorations were performed on July 30, 2007. A total of six (b) exploration pits were
excavated to determine subsurface conditions within the property. Due to the small size of the
backhoe provided for the exploration work each of the pits was advanced to depth of 4 to b feet
below existing grade. Exploration locations are shown on the accompanying Site and
Exploration Plan, Figure 1.
Exploration locations were established by tape measurement and pacing, using available
reference points, and should be considered accurate only to the degree of the methods employed.
Records of encountered soil types and conditions were maintained in the field by a licensed
engineering geologist from this office, and are summarized in the accompanying boring logs.
Soil samples obtained in the explorations were visually described by the geologist in the field.
Gary A. Flowers, PLLC
!9532 i26Avenue NE Shoreline.Wmhirtgdon99155.1106 206417.7640
Proposed Edmonds Retail Development GeolegicallGeotechnical Services Report
23-J' .St. SW (& Ntivv99, Edmonds, Washington
Geologic and Soils Mapping
The following geologic and soils mappings were reviewed in our study;
1) Geologic May of the Edmonds East and Part of the Edmonds West Quadrangles,
Washington, by J.P. Minard, 1983, U.S. Geologic Survey Miscellaneous Field
Studies, Map MF-1541
2) The Soil Survey of Snohomish County Area, Washington, 1983, U.S. Department of
Agriculture, Soil Conservation Service, Sheet 51.
The USGS mapping shows the terrain in the vicinity of the site to be formed over deposits of
Vashon age glacial Vashon age glacial till (Qvt). The SCS mapping shows the vicinity of the site
to fall within the Alderwood—Urban land complex, 8 to 15 percent slopes (soil unit 6)
classification. Alderwood series soils form over glacial till parent materials.
Soils encountered in our explorations are generally consistent with the USGS and SCS mappings.
The development site was found to be underlain by dense, poorly stratified glacial drift soils. We
interpret these materials as being the mapped Vashon till. The till consists of a poorly sorted
assemblage of sands, gravels and cobbles in a dense, grey, fine sand/silt matrix. In native or
slightly modified areas, generally on the lower or eastern portion of the site, our explorations
encountered less weathered, dense or better parent materials at depths of about 2.5 to 3.5 feet. A
zone of weathering has developed in the parent till materials. The weathered soils take on a
reddish brown color, and are in a loose to medium dense condition. The average thickness of the
looser weathered soils is estimated at about 2.5 feet.
Filling and/or ground modification were encountered in the northern portion of the site and along
the west boundary area. Indications of filling were recorded in exploration pits EP-3, EP-4, EP-5
and EP-6. Encountered fill depths were relatively minor, ranging from about 1.5 to 4.0 feet. We
also observed an area of very recent filling where a Vactor Truck had recently dumped its load of
fine grained sediment along the north property line. Other areas of deeper fills may be
encountered during development of the site. Accurate details of the extent of ground
modification will only become apparent at the time of construction of the new development.
Ground Water
No ground water seepage was observed in any of the exploration pits excavated for this study. In
addition, no indications of standing or flowing water or hydrophilic (grater loving) vegetation
was observed on the site.
During the wetter months of the year it may be possible for an interflow water to accumulate atop
the unweathered till sediments. Ground water interflow occurs as surface water migrates through
the looser, more permeable weathered zone in the till and perches atop the relatively
Gary A. Flowers, PLLC.
19532 12* Avcnuc Rt S"-line, Washinzon 98155-1106 206417-7640
Proposed Edmonds Retail Developmert GeotogicaYGeotechnieal Sert,ice-s Report
234"St. SW 0 H1,ry99. Edmonds. W' ashington
impermeable dense parent material. Depending on the slope of the ground surface (and interface
contact) within an area, the collected ground water may remain stationary, or migrate down
gradient along the top of the dense parent till surface. lntertlow is most active in the winter
months or during periods of prolonged rainfall. During these times, infiltration of perched
ground water into sandy seams or pockets in the dense parent material may also occur. This type
of activity is considered to be localized and is not an indication of a larger (regional) recharge
condition. Interflow tends to be seasonal and the level of activity generally decreases
significantly (or disappears) during the dry summer months.
CRITICAL AREAS
Geologically Hazardous Areas
Erosion Hazards
As per EMC 23.80.020 erosion hazard areas are 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. Erosion hazard areas are also
those areas impacted by shore land and/or stream bank erosion. Within the city of Edmonds
erosion hazard areas include:
1. Those areas of the city of Edmonds containing soils that may experience severe to very severe
erosion hazard. This group of soils includes, but is not limited to, the following when they occur
on slopes of 15 percent or greater:
a. Alderwood soils (15 to 25 percent slopes);
b. Alderwood/Everett series (25 to 70 percent slopes);
e. Everett series (15 to 25 percent slopes);
2. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular
soils and springs or ground water seepage; and
3. Areas with significant visible evidence of ground water seepage, and which also include
existing landslide deposits regardless of slope.
As discussed in the Geologic and Soils Mapping section above, the site is mapped as Alderwood
—Urban land complex, 8 to 15 percent slopes. Based on our exploration findings, observation of
open excavations on the adjacent property and site topography, we are of the opinion that this
classification is appropriate. Water erosion hazard for these soils is listed as moderate in the SCS
unit definitions. Therefore, the site does not meet the definition provided in the EMC for an
Cary A. Flowers, P'LLC.
19532 12" Avenue NE Shoreline, Wttihington 9815*-1106 206 4t7-7540
4
Proposed Edmondv Retail Dc veloprnent GeologicallGeotechnical Services Report
234'h St. SW 6' HvgK Edmonds, fk'ashingion
erosion hazard area. As such, and with the limited area of sloping ground and the level area
along H%tiry 99, standard erosion control practices will be suitable for this site.
Landslide Hazard Areas
Landslide hazard areas in Snohomish County are typically defined as; 1) areas of historic
landsliding, and areas subject to undercutting by streams, rivers or waves, 2) areas with slopes
steeper than 15% which intersect geologic contacts with a relatively permeable sediment
overlying a relatively impermeable sediment, and which contain springs or ground water seeps,
and 3) areas located in canyon or an active alluvial fan, susceptible to inundation by debris flows
or catastrophic flooding.
Our field measurements indicate that surface grades on this parcel are generally less than 15%.
No ground water seepage or geologic contacts were observed with the exploration pits or during
reconnaissance of the site. Considering the gentle site grades and dense or better glacial till
underlying the development area, it is our opinion that this property is not at risk from
landsliding.
Seismic Hazardr
Earthquakes occur in the Puget Lowland with great regularity. The vast majorities of these
events are small and are usually not felt by people. However, large earthquakes do occur as
evidenced by the 1949, 7.2-magnitude event, the 1965, 6.5-magnitude event, and the February
2001 magnitude 6.8 Nisqually earthquake. The 1949 earthquake appears to have been the largest
in this region during recorded history and was centered in the Olympia area.
Generally, there are four types of potential geologic hazards associated with large seismic events.
These include: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and
4) ground motion. The potential for each of these to impact the site is discussed below.
The nearest known fault is the Sound Whidbey Island Fault Zone. This fault zone consists of
multiple splays located to the north of the site. The exact locations of the fault splays are
unknown but are likely several miles to the north. The South Whidbey Island Fault Tone and
other nearby faults are being currently studied by the United States Geological Service (USGS)
and have been determined to be active and capable of producing large earthquakes. Much is still
to be learned about these fault systems but it is generally hypothesized that their recurrence
interval is several thousand years. Due to the suspected long recurrence interval, the potential for
surficial ground rupture is considered to be low during the expected life of the proposed
development.
Gary A. Flowers, PLLC ^'
19532 121h Avenue Ni; Shoreline, Wmhinxton 98) 55-11016 206- 4! 7.764it
Proposed Edmonds Retail Development Geological,Geoteehnical Senices Repon
23e St. SW 64 H► O9. Edmonds, Washington
s
Due to the lack of slopes and the dense nature of the underlying glacial till materials, it is our
opinion that there is no risk of damage to the proposed development, by seismically induced
landsliding on this site.
Based on the sediments encountered in our explorations, it is our opinion that the risk of
liquefaction is negligible.
In accordance with die 2003 International Building Code, Table 1615.1.1, the site soils within the
development area fail within the Site Class C" designation.
CONCLUSIONS AND RECOMMENDATIONS
On the basis of our geologic research and Feld explorations, the existing glacial deposits will
provide excellent support for the proposed retail structures and associated driveways and parking
areas. For foundations or paved areas to be placed on the weathered portion of the glacial till
sediments, the soils must be recompacted to a dense, nonyield.ing condition prior to concrete or
roadway fill placement. For foundations placed on the unweathered, very dense, glacial till, the
soils must be undisturbed. No structures should be placed on the encountered fill soils. The on -
site soils are very moisture sensitive and should not be worked during inclement weather. If
these soils become over optimum in their moisture content, they will be easily disturbed and
additional excavation may be necessary to reach bearing soils. If the soils are too dry at the time
of construction, it will be difficult to add water and obtain consistent moisture content
throughout. Therefore, the owner/contractor should be prepared to provide import granular
material, as needed, for structural backfill on the project during wet weather construction or
following extended periods of dry weather.
A perched interflow water zone may occur on the site during extended periods of inclement
weather. Although no ground water was observed its our exploration pits, interflow is typically
seasonal and will likely reduce significantly, or dry up, during the drier seasons of the year.
During wet weather periods the contractor should be prepared to deal with the interflow, as
necessary.
Site Grading
Site grading plans were not provided prior to completion of this report. However, due to the
relative gentle grade on the site, and the intention on the part of the client to work with the
existing grade, we anticipate that grading will be limited. The site should be cleared of all
vegetation, topsoil and existing fill soils that are not required as part of the landscape plan.
These materials should he removed from the site or stored for future landscape use.
Gary A. Flowers, PLLC.
19532 126 Avenue N!. Sht-elmr— Washington 98155-11 U6 206417.7640
Proposes! Edmonds Retail Development GeologicaliGeotechnical Servicev Report
23 `h S - SW ta, Hvvi.99, Fdmondv, Washinglon .s....�
If structural fill is necessary for site development it must be compacted to a dense, nonyielding
condition. Structural fill is defined as non -organic soil, placed in maximum 8-inch loose lifts
with each lift being compacted to at least 95 percent of the modified Proctor maximum density
using ASTM:D 1557 as the standard.
In the case of roadway and utility trench backfill, the structural fill should be placed and
compacted in accordance with current local or county codes and standards. The top of all
compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the
location of perimeter footings or pavement edges before sloping down at a maximum angle of
2H:1V. Structural fill placed in foundation excavations must extend a minimum distance of 2
feet beyond the edges of the footings.
Depending upon final grading design, it appears that the pavements for this project will be
supported by loose to medium dense, silty sand with some gravel (weathered glacial till) or
structural fill soils atop these soils. These soils will require recompaction to a dense, unyielding
condition prior to placement of any concrete, pavement or structural fill. Due to the fine grained
nature of the on -site soils, they will be subject to disturbance when above optimum moisture
content. If the subgrade soils become unstable they will require further excavation to competent
soils or moisture conditioning and compaction prior to installation of the pavement section.
All structural fill less than 4 feet below finished grade for the planned driveways and parking
areas should be compacted to 95 percent of the modified Proctor maximum dry density as
determined by ASTM:D 1557. Prior to placement of pavement base course materials over
natural subgrades, the area should be proof -rolled under the observation of a representative of
this firm with a loaded dump truck or other suitable equipment to identify any soft or yielding
areas. Any soft or yielding areas should be removed and replaced with granular structural fill
prior to continuing work. All areas to be paved should be crowned to direct storm water flaw to
the outside edge of the roadway.
Temporary Excavations
The appropriate slope configuration for excavation of soils depends on many factors including
the presence and abundance of ground water, the type and density or consistency of the soils, the
depth of cut, surcharge loadings (e.g., from adjacent structures. stock piles, construction
equipment, etc.), and the length of time over which the excavation is left open.
Construction slope angles required for stability and safety depend on a careful evaluation of all of
the above factors. Because of the many variables involved, the actual slope values required for
stability in open cuts can only be approximated prior to construction. At this site. we anticipate
that excavation cuts will encounter loose to medium dense modified ground and weathered
native soils, and underlying dense or better glacially consolidated parent soils. In our opinion,
temporary cuts of 0.5H to IV (horizontal to vertical), of up to b to 8 feet in the dense or better
Gary A. FloeFers, PLLC.
19532 12'^ Avenue NE Shurclinc. Washington 98155-1106 206417-7640
7
Propmed Edmonds ,detail LJevelvpment GeologicaliGeotechnical Services Report
234& St. SW rit Hia t, 99, L..dinond , f "ayhington
glacial soils, and I H to 1 V cuts in the overlying medium dense weathered glacial soils could be
used for planning purposes. Any loose materials should be laid back to a 1.514 to IV slope.
Some adjustments to these values are possible, but should be basest on site observations by this
office during construction. Actual sloping and maintenance of excavations during construction
should be made the responsibility of the contractor, as he is continuously present at the site to
observe the nature and condition of the excavation soils. Regardless of the construction method
used for excavations, the contractor should be aware and become familiar with applicable local,
state and federal safety regulations, including O.S.H.A_ excavation and trench safety standards.
Construction site safety and code compliance is generally the sole responsibility of the
contractor.
As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes
may have to be adjusted in the field. It may be necessary to cover the sides of temporary slopes
with plastic or otherwise protect them from the elements to minimize sloughing and erosion. As
ground water is encountered, the temporary slopes should be adjusted to a shallower gradient.
Permanent, unsupported cut or structural fill slopes should not exceed a gradient of 2H:IV.
Permanent. non-structural fill slopes should not exceed a gradient of 4H: IV.
Foundation Recommendations
We are of the opinion that the meditun dense or better native glacial till and/or glacial drift soils.
or structural fill placed over these materials, will provide a commonly acceptable level of support
for building and wall foundations. A net allowable design soil bearing pressure of 2,500 psf may
be used in design for footings set into appropriately compacted, weathered native site soils,
unweathered and undisturbed glacial till soils or approved structural fill placed over these
materials. For short term dynamic loads, a reduction of the factor of safety would be. appropriate
at this site, and a resultant increase of one-third for the above bearing pressures may be used.
Higher allowable bearing pressures will be appropriate for any foundation that is set to bear
entirely upon undisturbed glacial till soils. Should there be a need for higher bearing pressures,
such as for certain column loads, we should be contacted to discuss options with the structural
engineer.
Perimeter footings for the proposed structures should be buried a minimum of 18 inches into the
surrounding soil for frost protection. Settlement of footings placed as detailed herein should be
less than l" total and fa" differential over a 20 foot span between comparably loaded footings.
However, foundations placed on unapproved fill or disturbed soil may result in increased
settlement. All foundation excavations should be inspected by a representative of this firm, prior
to re -steel and concrete placement, to verify that the design bearing capacity of the soils has been
attained and that construction conforms to the recommendations contained in this report -
Gan, A. Flowers, PLLC.
19532 let aim NE Stxuchnc, Washing on 98155-1 1% 206417-7640
Proposed Edmonds Retail Development Cleologicat�Geotechnical Services Report
23 Sr" St_ SW td; Hw09. Edmonds, l ashnnZon
Lateral loads may be resisted by friction at the base of the footings and floor slab and as passive
pressure on the sides of footings. We recommend that an allowable coefficient of friction of 0.40
be used to calculate friction between the concrete and the underlying soil. Passive pressure may
be determined using an allowable equivalent fluid density of 250 pef. These values are allowable
and include a factor of safety of at least 1.5.
It should be noted that the area bounded by lines extending downward at IH:I V from any footing
must not intersect another footing or wall, or intersect a filled area which has not been compacted
to at least 45 percent of ASTM:D 1557. In addition, a 1.5H:I V line extending down and away
from any footing must not daylight because sloughing or raveling may eventually undermine the
footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils or
close to retaining walls unless the walls are designed for the additional surcharge load.
Retaining Walls
Retaining walls that are free to rotate may be designed for an active equivalent fluid pressure of
35 pef with level backfill or 55 pcf with sloping; backfill. If the walls are restrained and unable to
rotate they should be designed for an at rest pressure of 50 pcf for level backfill and 70 pcf with
sloping backfill. Loads from traffic, equipment or surcharges from adjacent structures should be
added to these values by the design engineer.
Resistance to lateral loads will be as provided in the Foundationv Recommendations section of
this report. All structural retaining walls or landscape walls taller than 3 feet must be lined with
a minimum of 12 inches of washed rock along their back sides to within I foot of finish grade, or
by an approved drainage mat such a MiraDrain or IncaDrain. The washed rock or drainage mat
must hydraulically connect to the footing drain.
We are unaware at this time of any mechanically stabilized earth retaining walls planned for the
site. If any such walls are planned that are over 4 feet in height, we should be contacted to
evaluate the walls and provide a suitable design.
Floor Support Recommendations
Slab -on -grade concrete floors may be placed over firm non -yielding native subgrades or atop
structural fill. Any material that has been disturbed and is not dense and unyielding should either
be recompaeted or removed and replaced with structural fill.
A capillary break layer consisting of 4 inches of washed pea gravel or other clean, washed,
granular material, and a heavy duty (minimum 10 mil), polyethylene plastic vapor barrier should
be provided under any floor slabs where moisture intrusion is a concern. If the vapor barrier
becomes compromised in any way during construction it should be replaced or an additional
layer added. Penetrations through the vapor barrier should be wrapped and taped.
- Gar}' A. Flowers, PLLC. - - -
19532 12' Avenue N8 Shurehne. Washington 98155• I 106 _-106-417-7640
Proposed Edmonds Reiad Developrneni Geological/Geoiedwical Services Repo.-t
23e St. Sti% p Hw3,99, Edmonds: Ff avhington
Site Drainage
All storm water runoff from impervious surfaces should be collected and piped into an approved
storm water drainage system. All perimeter footing walls and retaining walls should be provided
with a drain at the footing level. Drains should consist of rigid, perforated, PVC pipe surrounded
by washed pea gravel. The pipes should always be places] such that the perforations are located
on the lower one-third of the pipe section. The level of the perforations in the pipe should be set
no higher than the bottom of the footing and the drains should be constructed with sufficient
gradient to allow gravity discharge away from the buildings. Roof and surface runoff should not
discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain
that discharges into an approved storm water conveyance system- in planning, exterior grades
adjacent to walls should be sloped downward away from the structure to achieve surface
drainage.
Erasion Protection
The natural on -site soils contain a significant amount of fines and are considered to be moisture
sensitive. We anticipate that these materials, when disturbed, will be vulnerable to erosion from
both sheet flow and channelized flow. However, due to the gentle site gradient the erosion
potential should be addressed by standard erosion control methodology. The plan should
include, at a minimum, placement of silt fences along the lower reaches of the property. The silt
fences should be placed as per local municipal specifications, and be properly maintained. Soil
stockpiles should be covered with plastic sheeting during periods of inclement weather. During
rainy weather, areas stripped of vegetation and exposed backfill should be covered with plastic or
a minimum of 2 inches of straw mulch when not being worked. "lie construction entrance
should be rocked to minimize off -site soil transport.
SUMMARY
Based on our site reconnaissance and subsurface explorations, we are of the opinion that the
subject site is suitable for the proposed development provided the recommendations presented
herein are properly implemented.
We recommend. that we be retained to provide construction monitoring and consultation services
to verify that subsurface conditions are as expected and that construction conforms to the
recommendations in this report and the project plans and specifications. Should conditions be
revealed during construction that differs from the anticipated subsurface profile, we would be
able to evaluate those changed conditions, and provide alternative recommendations where
appropriate.
Gary A. Flowers, PLLC_
19532 12°i Avenue NE Shorclinc, Washington 98155-1106 206-417-7641)
10
Promised Edmonds Reiad Development GeologicaWeotechnical Services Report
234*St. SW HuyW, Edinonds, ff'ashington
Our findings and recommendations provided in this report were prepared in accordance with
generally accepted principles of engineering geology and geotechnical engineering as practiced in
the Puget Sound area at the time this report was submitted. We make no other warranty, either
express or implied.
Sincerely,
�t v't as
e�
m
Gary A. Flowers
Crary A. Flowers, P.G.. P.E.G.
Engineering Geologist
Attachments: Figure 1: Site and Exploration Plan
Appendix A —Exploration Pit Logs
Robert M. Pride, P.E.
Geotechnical Engineer
Gary A. Flowers, PLLC
19532 126 Avcnu-- NE Shomline. Washington 99155-11116 206-117-7640
-i&' /I
FFE 412
RETAA. 8
4,177 S.F.
.rEP-4
FFE 413
AutoZone
7n2 7X9 Sf
EP-3
-4
4 13
L
rT'l
i EP-2
43 EP-5
19P
RETAIL A
4.970 S.F.
FFE 412/v
EP4
LEGEND
EP-1 Approximate location of expIcratior. pit
A
SCALE IN FEET
SITE AND EXPLORATION PLAN FIGURE 1
ARY A. FLOWERS, PLCOMMERCIAL DEVELOPMENT DATE 9107
GLC
HIGHWAY 99 AT 234TH STREET SW
EDMONDS, WASHINGTON PiR.OJEC T NO. 07-076
Proposed Edmonds Retail Developme d t lenlogicaUGieotechnical Services Report
234`" St. Sir., IAwyQ()Fdmond,;, Washingtok:
APPENDIX A
EXPLORATION PIT LOGS
EP-1
o,a'- a.3' sod/topsoil
0.3'-3.5' medium dense, damp, brown, silty, SAND with gravel to 6" diameter (weathered
native)
3.5'-4.0' dense, damp, gray, silty SAND with gravel (glacial till)
BOH @ 4.0' No caving No ground water
EP-2
0.0'— 0.6' sod/topsoil
0.6'-2.6 medium dense, damp, brown. silty SAND with gravel to 6" diameter (weathered
native)
3.5'4.0' dense, damp, gray, silty SAND with gravel (glacial till)
BOH @ 4.0' No caving No ground water
EP-3
0.0'-1.5' loose, brown, silty SAND with gravel and minor debris (fill)
1.5'-2.6' medium dense, damp, brown, silty SAND with gravel to 6" diameter (weathered
native)
2.6'-4.0' dense, damp, gray, silty SAND with gravel (glacial till)
BOH @ 4.0' No caving No ground water
EP-4
0.0'— 0.7' forrest duff
0.7'- IT medium dense, dry to damp, brmvn, silty SAND with gravel to S" diameter and
minor debris (fill)
3.7'-4.0' medium dense, black, fine, sandy Sll-T with organics (relic topsoil layer)
4.0*-6.0' medium dense, damp, brown. silty SAND with gravel to 6' diameter (weathered
native)
BOH @ 6.0' No caving No groundwater
Gary A. Flowers, PLLk
19532 12* Avenue ME Shomhnc. Washingtim 9X155•1106 206417-7640
12
Proposed Edmond,; Retail Development GeolaKicaUGecrechnicat Serlices Repc-rt
234'h St. SFi' fa; fjuy99. Edmonds. Washington
EP-5
SAND with
0.0'— 3.0' Loose, brown, silty gravel to 8 inch diameter and minor debris (fill)
ilty SAND with gravel to 6" diameter (weathered
3,0'-5.0' medium dense, damp, brown, s
native)
BOH tt' 5.0' No caving No ground water
0.0'- 3.0' loose, brown, silty SAND with gravel and minor debris (fill)
3.0'-5.0' medium dense, damp, brown, silty SAND with gravel to 6" diameter (weathered
native)
BOH @a 5.0' No caving No ground water
Gary A. F'towers, PLLC .
M32 12i' Avenuc NE StH=hnc, Washington 98155-1106 2U6�I7-76dU