19-103025GEORGE GERG P. E.
vn-ELZTR c1-UKAI�TECFr- �TICAL
12701 111 th Ave E
Puye p, Wa 98374
(253) 241-333'At
GEOTECHNICAL REPORT
May 3 0, 2019
Client
Aleksander Adzhigirey
32822 5th Ave SW
Federal Way, WA
Adress
th
30523 28 Ave SW
Federal Way, WA 98023
Parcel # 416660-0600
I
Subject:
Geotechnical report, as defined by The City of Federal Way
Ordinance "Article II" Critical Areas", Division 4, Geologically
Hazardous Areas". The site is Lot 4, Block 6, Lakota Addition,
located at 30523 28th Ave SW, Federal Way, WA. It is off Dash
th
Point Road and 28 Ave SW, Federal Way, King County, WA.
It is in NW 1/4 of section 12, Township 21N, Range 08E, W.M.,
King County, WA. Parcel # 4.16660-0600
Prepared by:
George Gergis, RE
RECEIVED
JUN 21 2019
C
W
r
0
0
CITY OF FEDERAL WAY
COMMUHn YOEVELOpMENi
SHEET INDEX
Sheet 1-14
Sheet 12
Sheet 14
Sheet A
Sheet 15, 16 and 17
Sheet B
Sheet C
Sheet D
Adzhigirey Geo Report Index
May 2019
General Report
Construction Recommendations To The House
Development
Test Pits
Site Plan
Web Soil Survey
Reasonable Land Use Plan by J.S. Jones And
Associates Inc
Septic System Design by Westside Septic Design LLC
Proposed French Drain trench
Adzhigirey Geo
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May 2019
GEORGE GERGIS, P.E
12701 1111th Ave E
Puyallup, WA 98374
(253) 241-3334
May 30, 2019
Sergey Adzhigirey
ch
32822 5 Ave SW
Federal Way, WA 98023
Subject: Geotechnical report, as defined by The City of Federal Way Ordinance
"Article II" Critical Areas", Division 4, Geologically Hazardous Areas". The
site is Lot 4, Block 6, Lakota Addition, located at 30523 28I' Ave SW, Federal
th
Way, WA. It is off Dash Point Road and 28 Ave SW, Federal Way, King
County, WA. It is in NW 1/4 of section 12, Township 21N, Range 08E, W.M.,
King County, WA, Parcel # 416660-0600. Revised, amended report.
Dear Mr. and Mrs. Adzhigirey:
At your request we have carried out the necessary investigations to complete the above report in
compliance of the scope of work required by The City of Federal Way. The following letter
conveys our opinions, findings and conclusions.
(A) PURPOSE OF REPORT
This report is a revised and amended report from the original prepared on 2016. Changes and
modifications made necessitated the preparation of this report. The changes provided to us are as
follow:
1- Mostly changes to the on -site sewage system (septic system). These were due to
recommendations by the wetland reviewer/consultant that are related to develop and
construct within the wetland buffer.
2- The consultant presented some requirements to reduce the impact on the wetland buffer.
These were to easterly move the system in order to preserve some trees and other wetland
components.
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May 2019
3- The "Final revised septic", approved on 06/09/2019, was provided to us.
4- Also final " Reasonable Use Plan" prepared by J.S. Jones and Associates, dated
05/14/2019 was provided to us.
This report was prepared according to these final Septic and Reasonable Land use reports.
(B) SITE LOCATION
The property under discussion is a strip of land located off the east side of Dash Point Road and
the west side of 28th Ave SW. At that location both Dash Point Road and 28th Ave S are directed
in the north -south direction slightly to the northwest. Shortly to the north of the plat site, Dash
Point road changes direction to the south west, while 28 cnAve SW continues north but turns to
30 thAve S. The site generally is located about one mile south of Puget Sound in The City of
Federal Way area, King County, WA. At that location, The Dash Point Road was found to be
paved and developed. The 28 th Ave South is presently an access to this and other properties.
As stated in the above paragraph, the site is located directly east of Dash Point Road, however,
the access to the property is proposed to be utilizing a direct driveway that enters the site from its
east side street which is 28 th Ave SW near the north propertyline of the side.
(C) SITE TOPOGRAPHY AND DESCRIPTION
This subject site has never been previously developed and is almost presently remains in its
original natural condition.
The site generally contains slopes that may be considered medium to relatively steep.
During the site investigation, minor disturbance was found near the 28`h Ave SW Street. This
however did not affect the site topography or the remains in the natural condition, with medium
dense to dense vegetation.
During the site visits, field work and exploration, it was found that adjacent sites, to the north
and east of the subject lot, have been developed as single family residence lots. The immediate
lots of the same plat to the south of the subject lot remain undeveloped.
The subject site is almost a trapezoidal shaped parcel of land. The west rear leg spans about
1 OTfeet total length with 35'feet straight line and the remaining very flat curve. It runs in the
Adzhigirey Geo
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May 2019
north-west direction along Dash Point Road. Almost in the same direction, the east side is
101'feet long broken line, along The 28 cnAve South. The north is 478'feet and the south side is
about 450'feet, both extend in the east -west direction.
As previously stated, the property contains medium to steep slopes. The site is at its highest
uh
elevation at the east side front of 28 Ave South. From there the ground slopes down westerly to
the west and southwest toward Dash Point Road. From the top east area, for about ten feet, the
ground slopes with 40% grade to the west. That is reduced to 15% in the next 40'feet. It then
increases to an average of 27% for the next 200'feet.. From there till the west the slopes
continues to flatten to about 7% in the west direction. However, from the main street, Dash Point
up to the property, the slopes are about 65%, for about 15'feet only.
In total, the site covers an area of about one acre. Please refer to figure 1, attached to this report.
Presently, the drainage of the site is a natural surface drainage that runs westerly from the upper
areas in the east, and toward Dash Point. Due to the relatively flatter slopes of the site west area
of the site and the dense vegetation, it appears that most of the runoff is contained on site.
Originally and based on maps provided to us by the owner, Mr. Adzhigirey, it was found that
parts of the property were professionally designated as wetlands. A full wetland report was
completed and the result is stated in a later section.
(D) FIELD INVESTIGATION
Original investigation including the subsurface was made during the month of October 2015.
During which the writer visited the site and carried out a visual examination of the surface
features, slope conditions and vegetation. Two test pits were examined. Test pits allow to
investigate and to assess the subsurface conditions. The location of these pits is posted on Figure
1 and their description is as per the attached soil logs sheet. Recent site visit was made and no
changes were verified in the topography, the surface or any new slides or major erosion.
(E) GENERAL SITE SOILS
For this site, test pits were determined to be sufficient for this investigation for several reasons.
The type of soils expected on site was Indianola Loamy fine sand 0-15% or more. The verified
soil is evaluated as matching these soils mostly in the east area of the site areas. These do not
present danger of deep landslide due to the relatively denser substratum.
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May 2019
In addition, the slopes although relatively steep, they did not reach the limits of angle of rest. No
weaker layers are located at depth or top, which would result in any type of landslide. There was
no seepage or major mottling observed during the investigation in the Indianola.
As per "The United Stated Agriculture Department, USDA" and "The Natural Resources
Conservation Service, NRCS" , The Soil Survey maps show the eastern area of the site is
Indianola Soils, while the remaining to the west is Alderwood soils. The seepage in The
Alderwood is contained in small area with dense substratum.
No depressions or tension cracks, which confirm the above considerations. Please refer to a later
section "Soils Characteristics" discussing the soils components and effects in detail.
Therefore, in our opinion, the test pits were adequate and sufficient and there were no technical
or economical reasons to justified the need of deep soils boring.
Also the proposed construction is located in the eastern area of the site where the slopes are
moderate.
(F) FINDINGS
As mentioned earlier, the site generally, over most of its steep areas, was found to be covered
with medium dense to relatively dense vegetation covering. The vegetations were mix of some
mature, mid age and young trees, with dense overgrowth of berries, salal and other types. At the
time of the visit, and except for a small contained area, the site surface generally was found to be
dry and appears to be relatively well drained, with no signs or evidenced of ground water
seepage.
In the subject parcel, no signs of previous ground movement, as would be evidenced by scarps,
toppled or leaning trees, could be found on site. Our observations are detailed in the "seismic
hazard" and slope stability and landslide hazard" sections at the end of this
report. The parcel appears to be stable and we know of no historical landslide events in the
immediate area of the lot. The steep slopes were closely examined and appear to be stable.
(G) WETLAND
As previously stated, original based maps provided to us by the owner, Mr. Adzhigirey, shown
that parts of the property were designated as wetlands.
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May 2019
Complete wetland report was made to specifically assess the areas designated as wetland and
their buffers. The original report dated August 21, 2015 is made by "J. S. Jones and Associates,
Inc" of Issaquah. Attached was a Reasonable Land Use Plan. Subsequently, This was revised
multiple times on 11/22/16, 12/28/16, 12/31/18 to mostly addressing comments related to
wetlands. Final Reasonable Land Use plan was dated 05/14/19 by J.S. Jones and Associates
As per the wetland codes, the report clearly bordered the wetland areas and the associated buffers
that must be set aside from construction activities. Based on the maps and the proposed site plan:
a) The house will be to the east near the north PL to avoid the wetlands.
b) The on -site septic system will be about 125'feet to its west
c) The Civil Grading and Drainage Plans were prepared by Mr. Glen Code, P.E. of
Development Engineering PLLC dated 09/23/15. It recommends a 8'x27'x2' infiltration
trench that will be located just SW of the new house, about 70'feet from the 28t' Ave SW.
These all are as per the final Reasonable Land Use plans dated 05/14/19, stated and mentioned
above. Please see, attached is copy of this plan showing the details of the wetland, the buffers
and the locations of each of the mentioned items.
This front setback will allow the house to be away from the front slopes coming down to the
construction ground elevation from the street level. This area contains steep slopes
(I) CONCLUSIONS AND RECOMMENDATIONS
1. Discussion of Development
As mentioned earlier, the property under discussion has never been developed. It is proposed for
the construction of a single family residence. This report has been prepared to address the
proposed development. The access to this site will be through a direct driveway directing west -
east from The 28 Ave SW
As proposed, no major ground modifications are expected and we see no need for any change to
the site existing topography. The new structure proposed in the northeast area of the site, near
th
28 Ave South. This front setback will allow the house to be away from the front relatively
steeper slopes coming down from the street level.
Please refer to a later section addressing the difference in elevation between the street and the
construction ground level. This will be discussed to address the driveway and any surface water
from the street and the slopes itself.
Adzhigirey Geo
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May 2019
2. Soils Characteristics
The King County Soil Survey describes the soils of the site, as "InC, Indianola Loamy Fine sand,
4 to 15%". The Soils Conservation Service, states that other types such as Alderwood, Neilton
and Everett may be contained with these soils.
Based on the examination, in the development proposed site area, we found that generally the
soils contain a large amount of medium to coarse sand, which confirms with the Indianola soils.
The western area contained soils that are of type that may be considered Alderwood-Kitsap soils.
As per The Soil Conservation Services, The Indianola soils are a well drained soils having rapid
permeability in all of its layers. The substratum is a relatively soils that are fine to coarse sand.
To the west, the Alderwood soils however are less permeable due to the very dense substratum
layer which results in seasonal seepage and light to medium mottling. The slow permeability and
denser deep soils may cause perching that may occur atop during heavy wet periods. During our
investigation we observed seepage to the depth of about 3.50'feet.
For The Indianola, the surface runoff is medium and the erosion hazard is moderate to severe, for
the steep sloped areas. It may be considered similar for The Alderwood-Kitsap.
Our exploration have exposed a fine to coarse sand with silt below eight inches depth soils in a
medium dense condition up to about 60"inches. At that depth the soils become slightly denser.
Very light scattered mottling has been found at the top 42inches layer.
In our opinion, the site subsurface investigation reveals that the site soils generally conforms to
the above type described in The KCSS and the NRCS in the soils type and sometimes in gradual
condition from type to another but in steeper slopes. Please refer to the attached figure 2, for the
soils type description.
The site soils have adequate bearing capacity to support structural loads. All types of existing
soils are well accepted as fill especially the wet season. During these dry periods they may be
used provided that they are free of topsoil, debris and rock fragments larger than 6 inches.
However, if the moisture in the soil exceeded the optimum moisture, as defined by ASTM D-
1557-91, it will become impossible to reach 95% compaction of the maximum dry density of the
soils, as defined by the same test. Therefore the use of these soils in the rainy season or periods is
acceptable, if compaction is made to reach 95%. Otherwise structural fill may be needed, see
table 1 for specification. Generally, during wet weather construction, material with more than 6
percent fines will not be easily workable.
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For the soils described as medium dense, a bearing capacity of 1000 psf may be used in the
foundation design with an adequate factor of safety. A one- third increase in
allowable bearing capacity may be utilized for the short term loads such as the case in the wind
or seismic loads.
3- Wetlands
Please refer to the "wetland" section in page #4. The section describes the basis for the house
proposed location in the site eastern section. The attached plans show the wetland limits and the
area allowed to construct.
4- Landslide Hazard
Generally, Landslide Hazard Area are these area with slope of 40% or more and with a vertical
relief of ten or more feet. Also designated as Landslide Hazard Areas are those with over 15%,
containing hillsides intersecting geologic contacts with a relatively permeable sediment
overlaying a relatively impermeable sediment or bedrock combined with spring groundwater
seepage. Similarly are the areas which have a severe limitation for building site development
because of slope conditions, according to the Soil Conservation Service.
None of these conditions apply to the development area. The eastern slopes do not reach steep
slopes or the vertical relief. All of the remaining of the lot is under 30%% and down to about 8%
ground slopes. We have found no signs of erosion, or slides and is the site is stable. The mottling
and seepage observed in the pits is a sign of seasonal perching, the top less denser layer, about
40"inch deep, is relatively silty soft to medium dense and no construction is proposed in this
area. The development is in the sandy soils and the foundation will be recommended to be at the
medium dense layer. The small eastern area of the site contains slopes were that it is stable and
development may proceed as proposed considering the recommendations of this report.
5- Erosion Hazard
Erosion Hazard areas are usually defined as those areas classified having moderate to severe,
severe or very severe erosion potential by the Soil Conservation services.
Considering the sloped area as InC, that soil has a medium erosion hazard as per The Soil
Conservation service. A small area in the midsection reaches about 30% slopes and may be
considered as erosion hazard area. This however is not proposed for any development and
remains in its natural condition. It is well vegetated and requires no special care during and post
construction.
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May 2019
All other areas of the site are not considered erosion hazard. Please refer to the temporary and
permanent erosion sections of this report.
6- Temporary and Permanent Erosion Measures
Generally, the soils erosion hazard depends and its components and slopes. Because of
the relatively large amount of fines in the Indianola and Kitsap soils, it is relatively susceptible to
erosion when cuts, exposed surfaces exist, especially with wet weather. Long periods of water
exposure will cause erosion when the slopes reach about 30%. Therefore, we do not recommend
exposure of cuts for long times in wet or windy periods. Our recommendations in this regard will
follow and must be considered carefully to protect the site stability.
The site topography as exist does appear to necessitate medium cuts during the installation of the
structure foundation over the sloped ground. These cuts will be made to accommodate the
construction of the utilities, the drainage system, if any, and the foundation. All the exposed
temporary or permanent cuts must be protected by maintaining certain slope and protect its
surface from erosion, especially during wet periods.
The side slopes of the temporary cuts may be maintained at 1H:1.5V for The Kitsap, assuming
short period of exposure in the wet season, not to exceed few days. If open for longer periods, in
the wet season, we recommend that side cuts be flattened to 1 H: IV or
to be shored, if over 4.50'feet. The contractor is responsible to comply with the cuts state and
federal regulations, beyond the requirements of this report.
Retaining structures may be required when developing this site, as proposed in the future by the
owner. When needed, the following values may be used for that design:
Active lateral earth pressure 35pcf, Non restricted walls.
Active lateral earth pressure 45pcf, restricted walls
Passive lateral earth pressure 250pcf against native or well compacted
Coefficient of friction 0.32
Factor of safety of 1.5 is already considered for the coefficient of friction.
Areas downslope and surrounding any construction excavation should be protected from any
sedimented runoff by the use of silt fences (see the attached detail) or by covering the dirt piles
with plastic. Similarly, the concentrated runoff from upslope or surrounding areas should be
prevented from entering any construction excavation area by diverting the flow.
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All other areas of the site are not considered erosion hazard. Please refer to the temporary and
permanent erosion sections of this report.
6- Temporary and Permanent Erosion Measures
Generally, the soils erosion hazard depends and its components and slopes. Because of
the relatively large amount of fines in the Indianola and Kitsap soils, it is relatively susceptible to
erosion when cuts, exposed surfaces exist, especially with wet weather. Long periods of water
exposure Kill cause erosion when the slopes reach about 30%. Therefore, we do not recommend
exposure of cuts for long times in wet or windy periods. Our recommendations in this regard will
follow and must be considered carefully to protect the site stability.
The site topography as exist does appear to necessitate medium cuts during the installation of the
structure foundation over the sloped ground. These cuts will be made to accommodate the
construction of the utilities, the drainage system, if any, and the foundation. All the exposed
temporary or permanent cuts must be protected by maintaining certain slope and protect its
surface from erosion, especially during wet periods.
The side slopes of the temporary cuts may be maintained at 1 H:1.5V for The Kitsap; assuming
short period of exposure in the wet season, not to exceed few days. If open for longer periods, in
the wet season, we recommend that side cuts be flattened to 1H:1V or
to be shored, if over 4.50'feet. The contractor is responsible to comply with the cuts state and
federal regulations, beyond the requirements of this report.
Retaining structures may be required when developing this site, as proposed in the future by the
owner. When needed, the following values may be used for that design:
Active lateral earth pressure 35pef, Non restricted walls.
Active lateral earth pressure 45pcf, restricted walls
Passive lateral earth pressure 250pcf against native or well compacted
Coefficient of friction 0.32
Factor of safety of 1.5 is already considered for the coefficient of friction.
Areas downslope and surrounding any construction excavation should be protected from any
sedimented runoff by the use of silt fences (see the attached detail) or by covering the dirt piles
with plastic. Similarly, the concentrated runoff from upslope or surrounding areas should be
prevented from entering any construction excavation area by diverting the flow.
Adzhigirey Geo
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May 2019
All the excavated materials must be piled, stored and covered suitably until reused or to be
exported. This to be done in such a way not to spill onto slope faces, burying the vegetation in
the surrounding or downslope areas. Therefore protection of the lower areas to be undertaken by
the use of silt fences or covering of the dirt piles at minimum.
7- Site Drainage and Ground Water
The site soils have a rapid permeability in its upper layers and slower at depth. We do not expect
major variation due to the development, as proposed when the development is considering an
adequate value and system. For this type of soils a 1.50 In/Hr permeability may be used for the
Indianola, and is acceptable for the design of the any drainage system of the lot, if needed. If
needed, a site infiltration system should be a minimum of 25'feet from the top of the steep slopes
that are 30% or more. In such case there will be no changes or negative effect regarding the site
slopes.
The above ara a h recommendations, from our original re ort we found to be complied with
in "The final Reasonable Land Use" provided and attached plans.
Therefore, even if infiltration is to be used, the generated runoff from the new developed
impervious area is to have negligent effect on the site area considering:
1- The Indianola is a well draining soils.
2- Comply with top of slope setback
3- Temporary and permanent erosion measure is considered.
4- Utilizing an adequate permeability factors.
The final drainage system details are beyond the scope of this report.
8- Proposed permanent cuts & fill
Temporary cuts were discussed under the previous section " Temporary Erosion Measures".
Permanent cuts may be needed, depending on the development. If utilized, it should not exceed
2H:1 V. All permanent slopes must be as soon as possible protected at their faces by seeding with
grass or a suitable ground covering shrubs.
If room does not allow for that approach, a steeper slopes of 1H:6V may be used and protected
with rockeries. Those structures will require permits if their heights exceed 4.0'feet, and must be
engineered. Design and construction must comply with the rockery Association, The City of
Federal Way and other approved engineering methods. Other retaining structures may be used to
Adzhigirey Geo
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May 2019
provide larger spaces and required to be engineered when over 4.0'feet in height.
Permanent fill, if needed, should be also kept at 2H:1 V as a maximum finish slopes. Fill should
be compacted as mentioned earlier to 95% compaction. Fill should not be placed over grounds
with slopes exceeding 4H:1 V, unless tiered, designed and inspected, and as soon as possible
vegetated.
No runoff is permitted in the east and north setbacks without being controlled. These areas to be
well vegetated as detailed later. See the recommendation in Section (I).
9- Foundations and structures
All the foundations must rest on the native ground or compacted soil, both verified and
inspected to 1000psf with the minimum depth requirements. All the foundations may be
conventional spread foundation system.
Footing drains are required for this site. For the foundation, or as required in the retaining
structures, the drain shall consist of 11/2" washed gravel or rock with a 4"inch PVC
perforated pipe embedded in. These lines shall then be directed to the drainage system or to a
daylight location 0.50'feet below and 5.00'feet away from the foundation level, with a
splash block. The rock must be wrapped with filter fabric. The footing drain lines must not be
connected with the roof drain lines for a distance of 5.0'feet minimum.
We estimate the postconstruction settlement of the structures where supported on the
medium dense, 2000psf, soils to range from 1/4"inch on native. Maximum differential
settlement of the structures should be less than 3/8"inch, measured along 25'feet of continuous
wall footing, or between adjacent comparably loaded isolated footings.
All the ground surrounding the structure must be sloped away from the foundation with a 2%
slopes at minimum or 1 % if concrete or paved slabs.
10- Site vegetation removal
As usual, the construction activities on this site appear to require some removal of the existing
vegetation or ground growth to the east for the driveway and house areas, in preparation for the
development. All areas, post construction, adjacent to the structure and the top of the slopes, that
were affected by the development, require professional landscaping installation prior to the final
occupancy.
Adzhigirey Geo
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May 2019
Utilizing a deep rooted, less maintenance requirements, full year green type of plants are
recommended.
Please refer to the Construction Recommendation as er Section for the recommendation
to professionally vegetate the front eastern slopes
11- Seismic hazard
Seismic Hazard areas are usually defined as areas which possess either
an Alluvial surficial geologic unit and/or recessional outwash overlain by Barneston,
Everett, Neilton, Pilchuck or Spannaway soils as per The SCS description.
The Kitsap or Indianola are slow drained soils in most of its layers and with deeper and denser
substratum. Those soils are not of a type nor in a condition, which is prone to the phenomenon of
liquefaction. This occurs as a result of rapid horizontal accelerations during which a
rearrangement of the soil particle may cause a build-up in pore pressure and as this increases the
shear resistance decreases to a possible temporary total loss of shear strength. This causes the
soil to behave as liquid allowing major settlements. However, this is only possible with soils of
very uniform grain'size distribution in loose condition, which is not the case of this site. In
addition, There is no historical evidence of earthquake- induced slides in this area.
12- Slope Stability and Landslide Hazard
We believe that the danger of any landslide on this property caused by natural reasons, such as
seismic events, is unlikely. The investigation has shown a stable slope in an undisturbed
condition. We have noticed no tension cracks over or at the top of the slopes.
Also no signs of depressions, scarps or others defect were seen. No signs of previous ground
movements or major erosion were observed, such as leaning trees or old escarpments. This
confirms that no dormant, active or stabilized slides exist. The steep
slopes are relatively at about the critical grade slope and the degree of rest for these type of soils.
Surface erosion to these slopes may occur if affected by the construction.
Therefore, these slopes should permanently remain protected by complying with the buffer and a
setback and by being maintained permanently vegetated professionally.
In addition, the denser condition of the soils and the amount of the slopes with denser depth
which presents a landslides resistant soils.
Adzhigirey Geo
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May 2019
13- Setbacks and buffers
The following to be maintained as critical buffer areas or setback areas:
1) No area of the site is required to be maintained as buffer zone except as set by the
wetland report.
2) An 8 feet foundation setback from the face of the slopes to be maintained. As proposed in
the Reasonable Land Use plan, this is in compliance.
3) When complying with the- wetland report as per the attached proposed house
location, provides adequate setbacks for the needed slope stability.
4) Comply with the recommendations stated in Page #7 regarding the front eastern
slopes. Please see the attached detail regarding the runoff routing and
() CONSTRUCTION RECOMMENDATION TO THE HOUSE DEVDLOPMENT
The front entry slopes have the following effects:
1- The driveway will run from the street level down to the house construction ground level.
This is about seven to eight feet of elevation difference. The following is recommended
for the construction and placement:
(a) The driveway edges and sides may be sloped or retained by retaining walls. Please
refer to the specific section #5 "Temporary and Permanent Erosion Measures". The
section recommended both conditions of whether sloped sides or retaining wall.
2- These front slopes from the street level to the house foundation level may result in
generating some runoff to the house foundation level. This report recommends to route
and contains this flow. This may be accomplished by a combination of the following:
(a) Install berm at the top to route the flow from the street from entering the site.
(b) Install a French drain of 24" wide x30'.. dee'p fitted with a 4"perforated pipe,.at the toe
of the slopes. In order to prevent affecting the foundation place the trench 10'feet
away to the east of the foundation. The bottom of the trench is to be lower than the
footing bottom. Add a berm atop f the trench. See the trench location and detail on the
attached sheet.
(c) Professionally vegetate the slopes to prevent erosion.
Adzhigirey Geo
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May 2019
CONCLUSION
The development, as proposed, will have a minor effect on the site erosion, stability and
drainage. When the recommendations of the drainage, setback, erosion sections are complied
with, any negative effects will be minimum to negligent.
In conclusion, we believe based on the above, that the site should not experience landslides as
long as protected from erosion, drainage problems and the new development
maintains enough setbacks with adequate foundations.
LIMITATIONS
The information, recommendations and conclusions presented herein have been prepared using
generally accepted geologic and engineering practices and techniques in use in the
date the field investigation was conducted. This report is limited to identifying possible geologic
hazards as defined by The City of Federal Way Code mentioned above.
This report is limited to the stated purpose for the identified property and should not be applied
to any surrounding properties. We make no warranty either expressed or implied
with respect to any geologic conditions which can vary between sites and within any one site. If
conditions are encountered which appear to differ from those described in this
report, we should be notified immediately so that we may review, and either verify or modify our
opinions.
This report is for the information of the client only. Its reproduction or transmittal to a third
party, except in full, is prohibited without the permission of the writer.
We would like to thank you for the opportunity to be in your assistance in this report.
Should you have any questions regarding the content of this letter, please contact George Gergis
at (253) 241-3334. -1'-, } I „
Sincerely,
Georg G , P.E.
f
GEORGE GERGIS
12701 111th Ave E
Puyallup,WA 98374
LOG OF TEST PITS
Depth below Soil Group Description
Test pit #1
0.00'-0.07' SM Dark brown grayish silty
0.07'-4.20'
4.20'-5.50'
Test pit #2
0.00'-0.05'
0.05'-3.70'
3.70'-4.70'
Test pit #3
0.00'-0.05'
0.05'-3.70'
Page 14
Adzhigirey Geo
May 2019
with some gravel. Dry to moist
SM Soft to Medium dense brown to grayish
at depth grayish. Silty fine to medium sand. No
mottling. No seepage.
SM Grayish coarse sand with silt.
Medium dense to dense. No
Mottling or seepage. Moist.
SM Dark brown silty with some
gravel. Dry to moist.
SM Soft. dark brown silty fine sand.
No Mottling. seepage. Denser at
40"inches
SM Dense dark brown silty fine
sand. No Mottling. No seaapage
SM Dark brown silty with some
gravel. Dry to moist.
SM Soft to med dense. dark brown
silty fine sand. Light mottling at 36"
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BRIAN POTUCEK
FEDERAL WAY, WA. 95023
253,732.3792
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