HomeMy WebLinkAboutGEO2023-00047 Critical Area Ordinance, Update 2023 - GEO Geological Review - 9/21/2018 1
EIVED
May 16, 2023 JUL 1 1 2023
Mr. Victor Tran, Owner PLANNING 615 W. Alder Street
18841 East WA SR-106,
Belfair, WA 98528
vtrandevl icggmai l.com
Subject: Memorandum No. 1: Update to the Critical Area Ordinance(CAO)Report
Tran Residential Property
18841 East WA SR-106
Belfair,WA 98528
MTC Project No.: 23B101
Dear Mr. Tran:
This letter transmits our memorandum to our critical areas ordinance geotechnical investigation, originally
performed August 1, 2018, for the above-referenced property (MTC Project No. 18S231 with a CAO
Report, dated September 21, 2018). Materials Testing & Consulting, Inc. (MTC) performed this
geotechnical assessment to confirm that previously reported conditions remain unchanged, as part of a
consultation for future possible geotechnical recommendations and/or design.
On May 2,2023,MTC arrived onsite to provide a limited geotechnical assessment of the onsite slopes and
the immediate vicinity. The site and subject slope are located on a small lot with an existing single-family
residence, which is founded a moderate to steep slope, which descends to Lynch Cove to the Northwest.
From the front of the house at the crest of the slope,to the base of the slope, several old growth trees could
be seen growing generally straight indicating that no lateral movement has been occurring at this section
of the property. Additionally, dense vegetation and brambles are present across the site and slope. At the
base of the slope is a small seawall which appears to be in generally good condition,with adequate drainage
and no apparent evidence of imminent failure. Drainage around the perimeter of the house also appeared
to be adequate, and at the time of our visit no water was observed to be discharging on,or around the slope
face.
MTC did not find any evidence to suggest that the slope is currently at risk of instability,failure or obvious
movement. We did not observe any concerning erosional features such as large-scale channeling or the
undercutting of foundations. Nor did we observe large-scale landslide features or relict evidence thereof
(i.e.,hummocky terrane,head-scarps,downslope accumulations,etc.)that would suggest mass movement
has occurred in the past.
Environmental •Geotechnical Engineering•Special Inspection a Non-Destructive Testing•Materials Tasting
Burlington l Olympia I Bellingham I Silverdale I Tukwila
360.755.1990
www.mtc-inc.net
t
Memorandum No.1-Tran Residence CAO Materials Testing&Consulting,Inc.
May 16,2023 MTC Project No.23B 101
Generally,conditions onsite appear largely unchanged from the 2018 investigation and appear suitable for
development utilizing the information and recommendations presented in the referenced MTC Report.
Standard Erosion Protection
Erosion is one of the most common driving forces leading to slope instability. In addition to the above
commentary, the following general recommendations should be implemented in general to reduce long-
term erosion potential at the project site:
1. The ground surface adjacent to the improvements should be sloped to drain away at a 5%minimum
to prevent ponding of water adjacent to the structure. Footing drains and surface gradients should
be incorporated as needed for the building and site design to help maintain a dry building and
adjacent site area.
2. Minimize the volume and velocity of water that travels toward and down the slope face(via proper
choice of site development features including stormwater controls discussed herein).
3. Avoid further accelerating slope erosion and mass wasting due to human activity such as:
a) Adding side-cast debris to the slopes during or after construction
b) Using heavy construction equipment on or near steep slopes
c) Excavating on or near adjacent slope face outside of approved locations
d) Placing additional tailings or soils near the slope crest or on the face
4. Construction equipment,construction materials,and native and imported soils should not be placed
behind the erosion control devices. Suitable temporary erosion and sediment control measures
should be implemented and maintained as needed at the construction site during and immediately
after any ground disturbance occurs. Temporary areas bare of vegetation should be protected from
erosion via a blanket of straw or rolled erosion control product(RECP)during prolonged breaks in
site work and prior to reseeding or revegetation.
5. At the end of the project, all disturbed vegetation should be repaired and maintained until it is
established. Concentrated surface water should not be allowed to traverse the slope during or after
the construction phase of the project. Recommendations for long-term site drainage controls should
be followed as discussed above. Footing drains should be routed into closed pipes and tightlined
to the base of the slope to outlet in a drain course or ditch, tightlined to a pre-existing catch basin
for disposal, or as directed by local regulations. Outlets for these pipes should be protected from
erosion through the use of rip-rap or some other energy dissipating device.
6. Clearing of existing vegetation outside the proposed building area near to and on the slope should
be avoided except as approved by a qualified professional. This provides additional stability to
loose top soils and minimizes the effects of down-slope water movement. This is excepting removal
of dead or dying trees if posing a direct hazard to site installations or adjacent roadways.
7. Grading or excavation of soils during construction should be accompanied by grass reseeding and
re-vegetation as the project is completed. According to "Vegetation Management: A Guide for
Puget Sound Bluff Property Owners" (Manashe, 1993)the following types of vegetation provide
good to excellent erosion control:
ti
J •
Memorandum No.1-Tran Residence CAO Materials Testing&Consulting,Inc.
May 16,2023 MTC Project No.23B 10 1
Common Name Botanical Name DeciduotwEvergreen Mature Height r?fT
Vine- a fle _ Acer cricinatum Deciduous 10+
a Nolociscus discolor D ous
Willow Salix s Deciduous 10+
Snowberry S to boric os albus Deciduous
Rose Rose s2p. Deciduous 2-10
Salmortberry =M
Spectabil Deciduaus '.
Salal Gaultheria shallon Evergreen To 4
Or
011 grape
Rcd hucklcbetTv Vaccinium arvifolium Deciduous To 12
n
Servicebe Amelanchier alnifolia Deciduous 12+
Pacific madrone Arbutus menziesii Evergreen 70
,Ps ' ver een
t
I
t
Memorandum No. 1-Tran Residence CAO Materials Testing&Consulting,Inc.
May 16,2023 MT Project No.23B101
Closing Remarks
The information included in this memorandum should be considered"for information only"and should be
considered supplemental to the information contained in the referenced original report,and as such, should
be read in conjunction with the report. The selected recommendations presented in this memorandum are
not intended to supersede any specific corresponding recommendations contained in the original report.
All other recommendations of the above-mentioned reports remain valid,unless otherwise specified herein.
Our professional services were performed using that degree of care and skill ordinarily exercised, under
similar circumstances, by reputable geotechnical engineers practicing in this or similar localities. No
warranties,express or implied,are intended or made.
Mr. Tran, we trust this memorandum presents the information you require. If you have questions,please
do not hesitate to call.
Respectfully Submitted,
Materials Testing and Consulting,Inc.
Medhanie ecle, P.E. Marcus Van Valen,E.I.T.
Engineering Manager Geotechnical Division Manager
Memorandum No.1.-Tran Residence CAO Materials Testing&Consulting,Inc.
May 16,2023 MTC Project No.23B101
f,
q,
Top Left:Photo showing the overall site setting and condition(s),as seen from the midpoint of the adjacent lot to the North.
Bottom Left. Vegetation&overgrowth on the northern side of the existing residence;typical to the crest of slope.
Top Right: Rear of existing residence,facing East.Note the vertical deck posts,which showed no sign of eccentricity due to
slope movement or soil conditions.
Middle Right: Photo showing condition of existing seawall,where trickling water was observed dripping from the drain spouts.
Bottom Right: Typical conditions at base of slope,between seawall and existing residence.No evidence of erosion,poor soils,
or pumping/shoving was observed.
16
Ocn -7
PLANNING MTC
Materials Testing & Consulting, Inc. }
Geotechnical Engineering•Materials Testing•Special Inspection•Environmental Consulting
�d�M'als Ta,Nr�&ConwltinlF�n�.
September 21, 2018
Tina Tran c/o: John Dalberg RECEIVED
18841 East WA SR-106, 111 E Keen Rd
Belfair, WA 98528 Grapeview, WA 98546
(360)277-0206 J U L 1 12023
Subject: Tran Residential Property—Critical Area Ordinance 615 W. Alder Street
18841 East WA SR-106, Belfair, WA 98528
Geotechnical Engineering& Consulting Services
MTC Project No.: 185231
Dear Mr. Dalberg:
At your request, Materials Testing & Consulting, Inc. (MTC) has completed critical area study
performed and limited slope stability analysis at the above-referenced property, including site and slope
visual reconnaissance, limited subsurface testing, and review of available geologic literature. The project
site consists of an existing home with post-and-pier foundation on a coastal property. MTC understands
that the client intends to replace the existing foundation with conventional spread footings, and possibly a
daylight basement.
MTC understands a site investigation is needed to meet Mason County critical area requirements for
geohazard assessment and confirmation of the acceptability of the proposed development. The following
report presents the findings and conclusions of �Afr literature review and site investigation, addresses
inherent concerns and feasibility of proposed site development, and provides geotechnical
recommendations for planning and design intended to reduce the inherent risks associated with site
development within a potentially geologically hazardous area.
MTC has performed this geotechnical investigation and critical area study in accordance with project
discussions with the client and our Proposal for Geotechnical Services dated June 25, 2018, as well as in
consideration of Mason County municipal code and typical regional requirements for site review for
development within or adjacent to a geologically critical area. Relevant details regarding existing site
features and proposed development are addressed herein,as applicable to the project scope at this time.
i
Corporate • 777 Chrysler Drive • Burlington, WA 98233 • Phone 360.755.1990 • Fax 360.755.1980
SW Region • 2118 Black Lake Blvd. S.
Fax 360.534.9779
NW Region • 805 Dupont, Suite 5 • Belling ate, 98226 • Phone 360.647.6061 • Fax 360.647.8111
Kitsap Region • 5451 N.W. Newberry Hi11�3id;Shiite 101 • Silverdale, WA 98383 • Phone/Fax 360.698.6787
Visit our website: www.mtc-inc.net
, r
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Site Investigation Methodology:
On August 1, 2018,MTC visited the site to perform visual reconnaissance of the surface and topographic
features of the subject property and proximal slopes, as well as to conduct subsurface exploration for
geologic hazard assessment and site characterization. Site dimensions and general slope topography
were estimated and mapped at representative intervals using hand survey equipment as access allowed.
Salient slope features and existing vegetation were documented to assess general site and slope stability,
as well as to identify historic or current local erosional or subsurface instability. The slope was observed
and measured directly from within the site.
MTC advanced two (2) Wildcat Dynamic Cone Penetrometer (DCP) tests extending to depths of
approximately 16.0 and 18.0 feet below present grade (BPG) at representative locations along the slope
profile and within the project building area to document in-situ soil strength and generally characterize
subsurface stratigraphy. Penetrometer tests were terminated upon reaching practical refusal depth on
very dense or hard conditions. During penetrometer advancement, blow counts were recorded in one-
decimeter increments as a thirty-five-pound weight was dropped a distance of 15.0 inches. Blow counts
were then converted to resistance (kg/cmz), standard penetration blow counts (N-values), and
corresponding soil consistency,with complete results shown on the attached logs.
Direct observations of soils via supplemental Hand Auger (HA) borings adjacent to DCP locations were
also used to supplement interpretation of DCP data and classify soils. Observations and visual
classifications of the exposed subsurface soils were used to correlate blow count data with generalized
subsurface conditions. Inferences from those observations are described herein. Hand Auger boring logs
are also attached for reference.
A location and vicinity map is provided as Figure 1, Appendix Al. Exploration locations are shown
schematically on the attached site plan in Figure 2, Appendix A2. Typical measured or estimated slope
conditions are shown schematically on the attached topographic profile in Figures 3, Appendix A3.
Photos showing general site features are provided in Appendix B. Complete exploration logs are
presented in Appendix C.
Summary of Geologic Literature Review:
The Geologic Map of the Belfair 7.5-minute (1:24,000) Quadrangle, Mason Kitsap and Pierce Counties,
Washington published by the Washington State Department of Natural Resource (Polenz et al., 2009)
indicates site geology is mapped as Holocene-aged Landslide deposits (Qls) from the Alderwood
Landslide dated at approximately 1.1ka. These unconsolidated landslide deposits are highly variable
consisting of an unsorted, unstratified and, loose mixture of angular gravel (up to boulder-sized), sand,
silt and clay. The Alderwood landslide is believed to be seismically triggered bg movement and lateral
2
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
spread of from the Cascadia Subduction Zone but also may have small-scale movement according to the
review of historic photographs. A trace of the Tacoma fault zone is visible via lidar approximately 0.5
miles southeast of the project site. The fault line is estimated to be Holocene in age, and appears
consistent in extent with several mapped historic landslides along the regional Belfair coastal margin.
This landslide feature is mapped to compose the majority of the surrounding region and most of the
residences in proximity to the site.
Based on available information, shallow soils within the project area are mapped by the NRCS Web Soil
Survey as Alderwood gravelly sandy loam (Ac) with 15 to 30 percent slopes. Alderwood gravelly sandy
loam was formed by glacial drift/outwash in ridge and hill landforms. The soil is described to be
moderately well drained and typically consists of very gravelly sandy loam to depths of 60 inches and
beyond. Depth to the restrictive feature is reported to be between 20 and 39 inches and, corresponding
water table is expected between 18 and 37 inches below grade. The capacity of the unit to transmit water
is considered very low to moderately low with a ksat values between 0.00 and 0.06 inches per hour.
The Liquefaction Susceptibility Map of Mason County, Washington published by the Washington DNR
DGER (Palmer et al., 2004) shows the project site area as having a low susceptibility to liquefaction
during a seismic event, consistent with observed soil and groundwater conditions. No fault traces are
mapped to occur within or near to the site area.
Surface Observations:
The proposed area of development is a coastal residential property located northwest of WA SR-106 in
Belfair, Washington. Topography of the region is typically northwest-sloping toward Hood Canal with
moderate localized slopes. Adjacent parcels are similarly developed residential properties.
The subject critical slope makes up the entire proposed area of development; the existing residential
structure is cut into the slope, with the lower extent of property development defined by a concrete
bulkhead, and its upper extent defined by WA SR-106. Slopes adjacent to the subject structure measured
to be approximately 21 degrees. Benched areas above and below the subject structure measured
approximately 37 and 21 horizontal feet, and act as a driveway and backyard/drain field.
Vegetation upland of the driveway consisted of mature evergreen trees. Vegetation along the slope and
bulkhead typically consisted of low vegetation, bramble, and second-growth trees. Tree trunks generally
did not show obvious signs of excessive tilting or significant curvature that would indicate significant
long-term slope creep or instability.
3
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Subsurface Conditions:
A general characterization of on-site soil units encountered during our explorations is presented below.
The exploration logs in Appendix C present details of soils encountered at each exploration location. The
on-site soils are generally summarized as follows in stratigraphic order to depth:
• Sandy Cover Soils—Silty Sand with Gravel(SM):
Sandy surface soils were observed at the surface at testing locations within the area of
development and the critical slope. These soils were typically silty sand with gravel, loose to
weakly medium dense, brown in color, and dry. Gravel was typically 1.0 to 2.0 inches in
diameter, and minor tree and shrub roots encountered did not appear adverse in size or extent.
Thickness of sandy cover soils extended to approximately 2.0 feet BPG at both exploration
locations.
• Glacial Drift—Silt(NM):
Weathered glacial deposits (or derived from parental glacial drift) were encountered below cover
soils at both exploration locations. This layer typically consisted of silt with minor sand, was
medium stiff to stiff, brownish-gray to gray in color, and damp. This unit was encountered to
termination depths of 16.0 to 18.0 feet BPG at both testing locations. These soils transition from
soft to generally medium stiff below depths of 4.0 feet BPG upland of the anticipated upper
retaining wall, and at approximately 3.0 feet BPG in the vicinity of the lower retaining wall.
Surface and Subsurface Water Conditions:
The nearest significant surface water feature is Hood Canal, whose shores exist at the base of the
bulkhead at the base of the slope. No major surface water features were present within or adjacent to the
upland project site during MTC's reconnaissance in the summer season. The ground surface was
generally dry throughout the site and on the slope face.
An obvious groundwater table was not encountered by end depth of MTC's explorations conducted
within the anticipated area of development or along the slope. Soils in the vicinity of DCP tests and hand
auger borings among the proposed area of development and slopes were free of water seepage or
significant excess moisture. No seepage was observed across the site surface. The actual severity and
regularity of perched water conditions is unknown due to the limitations of observations conducted
during a single visit in the winter season.
MTC's scope of work did not include determination of seasonal groundwater elevation variations,
documentation of wet season site conditions, or conclusive measurement of groundwater elevations at
depths past the extent feasible for hand-operated explorations. Regional groundwater level is inferred to
4
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
exist below the depth of concern for this study, based on topographic conditions and site elevation,
vicinity surface water occurrences, and review of available well logs in the subject area.
Critical Area Conditions:
MTC performed reconnaissance to observe and document any indications of localized surface
degradation or large-scale slope instability. No obvious features were noted that would indicate an active
or prior slope failure, such as headscarps or downslope accumulations. Topography was generally
consistent, lacking significantly oversteepened areas, channelized runout zones, or hummocky zones. No
obvious evidence of rotational or translational failures or major toppling hazards was observed on the
slope in proximity of or downhill of the proposed improvements. No obvious failure features were
observed on adjacent slope areas visible from the subject property during the visit. The risk of erosional
hazard appears to be low on the slope face due to the established vegetation.
Surficial conditions of the upland pad and adjacent slopes may become partially saturated during heavy
rainfall events, due to the presence of shallow confining soil conditions. However, seasonal water
conditions and variations do not appear to have had a significant effect on site surface conditions, and
therefore may be expected to be intermittent as opposed to pervasive in nature.
MTC considered the potential for reactivation of the existing historic landslide boundary that the site
exists within. Rather than being a site-specific issue, this is a widespread regional dormant geohazard
feature, with many existing homes located within the mapped boundary. No known widespread efforts
have been taken by the county to mitigate future landslide hazards. Failure mechanisms of the historic
slide may be interpreted to be a series of complex interactions between geologic units, and naturally
varying slope safety factors at depth across wide extents of the coast, as a natural process of erosion and
weathering of elevated coastal sedimentary deposits. Failure mechanisms of deep-seated landslide events
are commonly at depths well beneath the depth and scope of most residential construction projects,which
are typically of a weight and impact that is insignificant to global stability and safety factors.
Based on field observations and the map resources, MTC does not consider the site to be at immediate
risk of landslide hazards, provided that recommendations in this letter are followed during construction
and development.
Slope Stability Analysis:
Considering the conditions of the potential critical slope and shallow soil conditions, specific foundation
requirements must be followed for successful construction at this location. Slope factor of safety were
determined by the following the sirtiplified relationship (Landslides: Investigation and Mitigation, Turner
and Schuster, 1996):
5
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Factor of Safety(FS) = Tan Tan(a)
Where = Inferred Internal friction angle of soil
a = Angle of slope or projection plane.
Underlying glacial drift soils appeared to be in a medium stiff to stiff condition, with exposed faces
inclined shallower than the inferred safety projections. Accounting for potential surcharges of new
structures, potential failure plains were assumed to emanate from the toe of the nearest descending
feature, in this case, the approximate base of the bulkhead. In general, safety projections are to be
measured from the top of an adjacent retaining wall, as they are considered stabilization features.
However, grade adjacent to the wall does not extend over the derived safety projections, therefore safety
projections were considered from the approximate base of the seawall for general protection against
potential surcharge loads. If alternative construction methods requiring additional mathematical slope
analysis are selected, less conservative parameters may be considered. An inferred 0 = 32 degrees
friction angle was assigned to the generally medium stiff silts and sand profile for use in assessing slope
factor of safety and determining a suitable conservative building setback. Target factor of safety for
residential structures is typically FS = 1.5 for static analysis. Factor of safety is an indication of stability;
an FS = 1.0 or below corresponds to the point of failure. The setback projection angle for a suitable
factor of safety is found by using:
Factor of Safety(FS) -+ Tan Tan (a)=Tan(32)/Tan (a)= 1_5
a = 22 degrees
MTC's profile estimates were used to create a projection from the slope base for an a = 22-degree
projection angle. This geometry meets county critical area ordinance factor of safety requirements for
residential development.
Discussion and Recommendations:
The findings of MTC's reconnaissance at the subject site appear broadly consistent with available
geologic literature and do not indicate that any excessively prohibitive conditions exist for the anticipated
level of development. Designation as a critical area is based on the mapped historic slope failure rather
than present site-specific stability concerns. Based on the information herein, MTC provides the
following development and site-specific recommendations to be followed to minimize the inherent risks
of owning a sloped property.
6
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Setbacks
MTC understands the footprint of the house and deck will remain generally unchanged, with no future
developments planned to encroach on any existing setbacks. Upland slopes in line with the house are
generally stabilized by existing retaining features, and inclination of proximal slopes do not intersect any
factor of safety projections. Therefore, MTC does not recommend any additional setbacks or analysis be
conducted at this time.
Foundations
For general foundation design considerations, MTC recommends referring to guidelines and parameters
of the International Building Code (IBC, 2015; or most recent edition at the time of construction).
Footings should be placed to a minimum depth in accordance with the setback and factor of safety
projection criteria above, as well as meeting minimum IBC (2015) requirements. Excavations should be
performed during the dry season. Cutting to grade should be done with a smooth blade bucket to limit
disturbance of subgrade soils.
The proposed home modification may utilize either shallow continuous footings with slab-on-grade, or a
daylight basement foundation, depending on the chosen development style. In either situation, MTC
recommends overexcavation of loose, soft, or organic-rich cover soils down to firm bearing conditions.
New foundation elements and their fill shall be embedded such that the bottom of the closest face of the
foundation fill material is placed below a 22-degree plane projected upward from the base of the existing
bulkhead. This embedment is intended to protect future developments from any potential degradation
related to surcharges imparted by the new structure, for the design life of the structure, and to protect the
bulkhead from any adverse effect of the improvements. These measurements and delineations are
schematically detailed in the attached slope profile in Figure 3 of Appendix A3. Regional slope stability
modeling beyond conditions identified within the parcel is considered to be outside the scope of typical
residential improvements.
For continuous footing elements, upon reaching bearing strata, we recommend benching foundation lines
flat. Continuous perimeter and strip foundations may be stepped as needed to accommodate variations in
final subgrade level. We also recommend maximum steps of 18 inches with spacing of at least 5 feet be
constructed unless specified otherwise by the design engineer. Structural fill may then be placed as
needed to reestablish final foundation grade.
• Foundation Preparations:
Within the proposed building area, an elevated risk of settlement potential exists due to the presence
of shallow medium plastic fine-grained soils below the surface. Mitigation of these soil conditions
7
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
can typically be accomplished by overexcavation, and replacement with structural fill, in combination
with lowering of footing grades.
MTC recommends that foundation subgrade be overexcavated to a minimum depth of 3 feet below
present grade. If, during excavation, poor soil conditions are encountered or additional
overexcavation is required, MTC recommends footing grades be reestablished by placement of
imported structural fill.
• Allowable Bearing Capacity:
An allowable bearing capacity of 1,500 pounds per square foot (psf) for footings placed overtop a
minimum 6-inch section of compacted structural fill as presented above is recommended. Native
soils below structural fill should be suitably firm, verified by an MTC soils inspector. The allowable
bearing capacity may be increased by 1/3 for transient loading due to wind and seismic events.
If, during design, greater than anticipated loads requiring a higher bearing capacity are considered,
MTC may be contacted to provide consultation on the feasibility of alternative foundation designs
and allowable bearing capacities.
• Structural Fill:
All structural fill shall be compacted to a firm and unyielding condition and at least to 95 percent of
the modified Proctor maximum dry density per ASTM D1557. Imported structural fill material
should also conform to Section 9-03.14(1), Gravel Borrow, of the most recent edition of the WSDOT
Standard Specifications.
Note: For lateral and bearing support, structural fill placement below footings shall extend at
minimum a distance past each edge of the base of the footing equal to the depth of structural fill
placed below the footing[e.g.,for a 2.0 foot wide footing,fills placed to approximately 1.5 feet below
footing grade will require a minimum bac>fill width of 5.0 feet (1.5 feet each side plus 2.0 foot width
of footing.
• Minimum Footing Embedment:
For a shallow perimeter and spread footing system, all exterior concrete footings shall have a final
embedment of 18 inches and all interior footings shall be embedded 12 inches below the lowest
adjacent finished grade, and not less than the depth required by design. Minimum depths are
referenced per IBC requirements for frost protection; other design concerns may dictate greater
values be applied. Raising of exterior site grade may be utilizes to achieve required embedment.
8
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
• Footing Drains:
Footing drains should be incorporated to maintain dry foundation conditions. MTC recommends
footing drains employ 4-inch minimum perforated pipe. Footing drains shall be backfilled with free-
draining material (as specified below for wall drainage) wrapped in filter fabric. Footing drains
should be tightlined separately from roof drains to a catch basin system or to a permanent discharge
point at least 10 feet from the structure. A schematic illustration of a typical footing drain is shown
below.
Foundation Backfill:
Interior Floor Slab Impervious Upper I
Final grading per project specifications
Stem
Wall
Filter Fabric Wrap
�f�ftirtirtifyr1r
tirtirtir4r�ryryr
4rLrtiitiftirtirtif
ti
r.r•r•r•r.r.ti.. Drain Rock
.ti.ti
•r•r•r•r•r•r•
ryr:}.r1
r 4-inch Diameter Perforated Pipe
Footing r (graded to drain by gravity)
Retaining Wall Recommendations:
The following recommendations pertain to the design (by others) of any new laterally loaded retaining
structures founded on suitable subgrade, or on properly compacted structural fill, as detailed below.
These recommendations are not applicable to exceedingly sloping backfills, backfills composed of non-
granular soil materials, braced or tied-back walls, or for walls greater than 10 feet in height. MTC
expressly recommends that we review final plans and specifications for retaining walls to ensure
consistency with the recommendations presented herein, and to provide additional geotechnical
consultation and recommendations as needed for final design and construction.
• Foundations
MTC recommend retaining wall foundations bear on suitably medium stiff to stiff dense native silty
soils and adhere to the o n a t n reco en a ns etat a
• Active and At-Rest Pressures:
Yielding (cantilever) retaining walls should be designed to withstand an appropriate active lateral
earth pressure, whereas non-yielding (restrained) walls should be designed to withstand an
9
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
appropriate at-rest lateral earth pressure. The at-rest case is applicable where retaining wall
movement is confined to less than 0.005 H, where H is the wall height. If greater movement is
possible, the active case applies. A wall movement of about 0.02 H will be required to develop the
full passive pressure. These pressures act over the entire back of the wall and vary with the backslope
inclination. For lateral pressures relative to seismic loading conditions, we recommend applying a
uniform blanket seismic surcharge of 10psf x Height for a generalized design situation. For retaining
walls up to 10 feet in height with a level backslope and retaining intact native soils, we recommend
using parameters for active and at-rest pressure (given as equivalent fluid unit weights) provided in
the following table:
For retaining walls up to 10 feet in height with a level backslope and retaining intact native soils, we
recommend using parameters for active and at-rest pressure (given as equivalent fluid unit weights)
provided in the following table:
Table 1. Wall Pressures
UNIT ACTIVE AT-REST SEISMIC
SOIL TYPE CONDITION WEIGHT PRESSURE PRESSURE SURCHARGE
PCF PSF*H) PSF*H) PSF*H
Native Soil(ML) Retained 100 45 100 10
Structural Fill Retained/Backfilled 125 35 55 10
Retaining Wall Construction Recommendations:
• Excavations:
The duration of time that excavations behind walls remain open should be limited to only as
necessary to prepare the base pad and placement of the wall features, backfilling with drain rock
and approved fill immediately. Temporary worker protections such as trench boxes or temporary
shoring may be required for entering excavations deeper than 4 feet, and all OSHA safety
regulations should be observed. Extended open cut periods or work proceeding in wet weather
may require surface coverings, lesser cut angles, and/or temporary bracing be applied. We
suggest a minimum 5-foot horizontal buffer be maintained from the temporary cut to the upslope
property lines(to allow for some near-surface disturbance during excavation).
• Wall Drainage:
To preclude build-up of hydrostatic pressure, we recommend a minimum width of 1 foot of clean,
granular, free-draining material extend from the footing drain at the base of the wall to the ground
surface immediately behind the wall. Native soils are not considered suitable as drainage
material. Imported wall drain aggregate should conform to WSDOT Standard Specification 9-
03.12(4) Gravel Backfill for Drains or 9-03.12(5) Gravel Backfill for Drywells. A filter fabric
10
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
suitable for use in soil separation and water transmission is recommended to be placed against
retained soil cuts behind the wall (if present)to limit migration of fines into the drain corridor.
• Wall Backfill:
Native material is not considered suitable for wall backfill due to its elevated fines content. For
additional wall backfills as needed, soils should be relatively granular with less than 5 percent
fines(material passing the U.S. No. 200 sieve). MTC recommends wall backfill import material
to conform to WSDOT Standard Specification 9-03.12(2)Gravel Backfill for Walls.
• Wall Backfill Compaction:
It is recommended that wall backfill directly below pavement or other permanent structures be
compacted to 95 percent of the modified Proctor maximum dry density per ASTM D1557. Wall
backfill supporting landscaping elements and other non-structural components should be
compacted to a relatively firm and unyielding condition.
Drainage Controls
MTC recommends proper drainage controls for mitigating the increased potential for stormwater runoff
should be implemented along with site development to protect conditions of the site and slopes. MTC
anticipates on-site infiltration potential is infeasible due to the presence of shallow silty soils within the
subject site. MTC does not recommend dispersion or infiltration of collected stormwater between the
proposed development and slope, or on the slope itself, as increased runoff or localized stormwater
inundation can negatively impact long-term erosional and global slope stability.
MTC recommends roof and footing water sources be tightlined away from the building to an existing
upland catch basin and stormwater system, or down the slope to be released beyond the bulkhead using
appropriate energy-dissipating features at the outfall to minimize point erosion. Roof and footing drains
should be tightlined separately, or should be gathered in an appropriately sized catch basin structure and
redistributed collectively. If storm drains are incorporated for impervious flatworks (driveways, patios,
etc.), collected waters should also be discharged according to the above recommendations. All drainage
tightlines should be composed of appropriately sturdy material (such as rigid PVC), sized adequately
according to anticipated flow, and anchored sufficiently. MTC recommends slope tightlines be inspected
by the owner periodically to look for signs of damage or displacement requiring repair.
Site Grading and Permanent Slopes
MTC recommends that any new permanent graded slopes be inclined no greater than 3H:1 V. MTC also
recommends permanent slopes and undeveloped surfaces be planted with a deep-rooted, rapid-growth
vegetative cover as soon as possible after completion of slope construction. Alternatively, slopes may be
11
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
covered with plastic, straw, etc., until they can be landscaped. Cut or uncontrolled fill contaminated with
organic or manmade debris are not suitable for reuse as structural or grade fill. We recommend that fill
placed on slopes steeper than 3:1 (H:V) be `benched' in accordance with hillside drives entry of section
2-03.3(14) of the WSDOT Standard Specifications. We recommend any earth embankments be designed
by a qualified civil site designer.
Erosion Controls and Vegetation Improvements
Heavy compaction equipment and excessive vibratory activities should not be used adjacent to site
slopes, or the existing wall features. In general, vibratory plate or"sled"compactors are often sufficient.
Stockpiling of excavated tailings and side cast is to be prohibited above, near, or on slopes & walls.
Tailings should be removed to an inland area of the site, sufficiently away from the crest if temporary
storage of exported/imported materials is required. Marginal areas disturbed during construction should
be revegetated at the end of the construction phase,preferably using a pre-determined planting schedule.
If plans change to incorporate deep trenching, or additional excavations, or the type of installation
changes, MTC should be contacted to reevaluate site conditions and provide further analysis. If
additional developments, such as drainage features or other structures are considered, MTC should also
be contacted for further site analysis,applicable to the type and extent of development or construction.
Disturbance of the ground surface and existing vegetation outside of the planned building footprint
should be avoided in the vicinity of the slope crest as recommended above. Marginal landscape areas
disturbed during construction should be revegetated at the end of the construction phase.
Following construction and for long-term site use, maintaining existing upland vegetation and installing
additional beneficial ground plantings within the ancillary vicinity of the improvements and near the
slope crest is encouraged, assuming installation is done in a manner that minimizes slope .face
disturbance and erosional hazard in the long term. Adding resistive vegetation will increase the erosional
and hydrologic resistance of the slope, and assist in retaining cover soils. Further information and
recommendations for erosion control including typical beneficial native plantings for sloping areas are
provided herein. However, major landscaping alterations should not be undertaken without the
involvement of a qualified professional. In general, MTC recommends avoiding altering the area near
the slope or on the slope face by terracing or similar landscaping unless adequately designed as part of a
comprehensive improvement which also takes into account surface stability. In the event that surface
alterations are proposed outside of the planned building footprint,MTC should be contacted to review the
geotechnical feasibility of landscaping plans.
12
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Erosion is one of the most common driving forces leading to slope instability. In addition to the above
commentary, the following general recommendations should be implemented in general to reduce long-
term erosion potential of the slope below the project site and maintain the present slope stability:
1. The ground surface adjacent to the building should be sloped to drain away from the building pad
and slope at a 5% minimum to prevent ponding of water adjacent to the house. Footing drains
and yard drains should be incorporated as needed for the building and site design to help maintain
a dry building area.
2. Minimize the volume and velocity of water that travels toward and down the slope face (via
proper choice of site development features including stormwater controls discussed above).
3. Prior to construction, a silt fence and/or a continuous line of straw bales should be placed on the
slopeward edge of the construction area. Heavy construction equipment, construction materials,
or native and imported soils should not be placed behind the erosion control devices. Suitable
temporary erosion and sediment control measures should be implemented at the construction site
during and immediately after ground disturbance occurs. Temporary areas bare of vegetation
should be protected from erosion via a blanket of straw or rolled erosion control product (RECP)
during prolonged breaks in site work and prior to reseeding or revegetation.
4. Grading or excavation of soils during construction should be accompanied by grass reseeding and
re-vegetation as the project is completed. According to "Vegetation Management: A Guide for
Puget Sound Bluff Property Owners" (Manashe, 1993) the following types of vegetation provide
good to excellent erosion control:
Common Name Botanical Name Deciduous/Evergreen Mature Height t
Vine Maple Acer cricinatum Deciduous 10+
Oceans pray Holodiscus discolor Deciduous 10+
Willow Salix spp. Deciduous 10+
Snowbe Symphoricarpos albus Deciduous 3+
Rose Roses . Deciduous 2-10
Salmonberry Rubus s ectabilis Deciduous To 12
Salal Gaultheria shallon Evergreen To 4
Oregon Grape Mahonia spp. Evergreen To 6
Red huckleberry Vaccinium parvifolium Deciduous To 12
Evergreen Vaccinium ovatum Evergreen To 8
Serviceberry Amelanchier alnifolia Deciduous 12+
Bi leaf Maple Acer macro h llum Deciduous 60
Pacific Madrone Arbutus menziesti Evergreen 70
Douglas Fir Pseudotsu a menziesii Evergreen 200+
13
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Closing Remarks:
The project location is designated by the county as a potential critical area. Upon acceptance and use of
this report, and its interpretations and recommendations, the owner shall agree to indemnify and hold
harmless MTC, including its owners and employees, from any adverse effects resulting from
development and residence in a critical area. Ultimately it is the owner's choice to develop and live in a
geologically hazardous area, and therefore the future consequences, both anticipated and unknown, are
solely the responsibility of the owner. By using this report for development of the subject property, the
owner must accept and understand that it is not possible to fully anticipate all inherent risks of
development within a potentially geologically hazardous critical area. The recommendations provided
above are intended to reduce,but not eliminate, such risks as is practically feasible from the point of view
of geotechnical engineering.
Our professional services were performed using that degree of care and skill ordinarily exercised, under
similar circumstances, by reputable geotechnical engineers practicing in this or similar localities. No
other warranties, express or implied, are intended or made. We trust this letter satisfies your
requirements at this time; however, should you have any questions, please do not hesitate to call the
undersigned at(360) 755-1990.
Regards,
Materials Testing and Consulting,Inc.
ERTF
n,
w y iX. r
tv
50966
C/S'rB���
Ss�ONAt, LNG 09-21-2018
Luke Preston McCann, G.I.T. Medhanie G. Tecle,P.E.
Senior Geologist Engineering Manager
Attached: Limitations and Use of this Report
Appendix A1. Location and Vicinity Map
Appendix A2. Aerial Photo Overview with Test Locations
Appendix A3. Slope Profile
Appendix B. Photos of Site Reconnaissance
Appendix C. Exploration Logs
14
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Appendix D. Laboratory Test Results
15
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Limitations and Use of This Letter
Recommendations contained in this report are based on our understanding of the proposed development
and construction activities, our field observations and exploration and our laboratory test results. It is
possible that soil and groundwater conditions could vary and differ between or beyond the points
explored. If soil or groundwater conditions are encountered during construction that vary or differ from
those described herein, MTC shall be notified immediately in order that a review may be made and
supplemental recommendations provided. If the scope of the proposed construction, including the
proposed loads or structural locations, changes from that described in this report, our recommendations
shall also be reviewed.
We have prepared this letter in substantial accordance with the generally accepted geotechnical
engineering practice as it exists in the site area at the time of our study. No warranty, expressed or
implied, is made. The recommendations provided in this report are based on the assumption that an
adequate program of tests and observations will be conducted by MTC during the construction phase in
order to evaluate compliance with our recommendations. Other standards or documents referenced in
any given standard cited in this report, or otherwise relied upon by the author of this report, are only
mentioned in the given standard; they are not incorporated into it or"included by reference", as that latter
term is used relative to contracts or other matters of law.
This letter may be used only by Mr. Dalberg, the current property contractor, and their design
consultants and only for the purposes stated within a reasonable time from its issuance, but in no event
later than 18 months from the date of the report. Note that if another firm assumes Geotechnical
Engineer of Record responsibilities they need to review this report and either concur with the findings,
conclusions, and recommendations or provide alternate findings, conclusions and recommendation under
the guidance of a professional engineer registered in the State of Washington. The recommendations of
this report are based on the assumption that the Geotechnical Engineer of Record has reviewed and
agrees with the findings, conclusion and recommendations of this report.
Land or facility use, on- and off-site conditions, regulations, or other factors may change over time, and
additional work may be required with the passage of time. Based on the intended use of the report, MTC
may recommend that additional work be performed and that an updated report be issued. Non-
compliance with any of these requirements by Mr. Dalberg, the property owner or anyone else will
release MTC from any liability resulting from the use of this report by any unauthorized party and Mr.
Dalberg agrees to defend, indemnify, and hold MTC harmless from any claim or liability associated with
such unauthorized use or non-compliance. We recommend that MTC be given the opportunity to review
the final project plans and specifications to evaluate if our recommendations have been properly
interpreted. We assume no responsibility for misinterpretation of our recommendations.
The scope of work for this subsurface exploration and geotechnical report did not include environmental
assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the
soil, surface water, or groundwater at this site.
16
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Appendix Al. Site Vicinity and Location Maps
Site VicinitN'
?;
o "fair
Sktaknmisfi AHYy
Site Location ��*
IL
Got '6��-Washi�gton 166
Maps Source:
Google Imagery 2018 �
Materials Testing & Consulting,Inc. Site Vicinity and Location Maps FIGURE
2118 Black Lake Blvd SW 18841 E WA SR-106
Olympia, WA 98512 Belfair, WA 98528 1
17
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Appendix A2. Site Overview
{
Parcel Extent
18 861 E STATE
Existing Concrete }
Bulkhead 4-
IIood Canal
House
r and
DCP/HA-1 Deck
DCP/HA-2
Existing Rockery
Wall
Upper Retaining r
A
WA-SR 106
-188 21 E STATE ROUTE 106
0 40 SCALE IS APPROXIMATE Maps Source:
(Based on site measurements Mason County Assessor
and mapped topography) Accessed 9/4/18
SCALE(FEET) *Not for Construction
1 inch=40 feet
Materials Testing& Consulting,Inc. Site Overview FIGURE
2118 Black Lake Blvd SW 18841 E WA SR-106
Olympia, WA 98512 Belfair, WA 98528 2
18
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Appendix A3. Slope Profile
EAST Slope Profile A — A' WEST
DC.P-1 A'
Refusal at
A D -16 feet BPG
('P-2 ..Refusal at
WA-SR 106 -18 feet BPG -
��` Existing House Cut
io Existing Overhang
20' I Oo i
&deck
37' 1...I...................................... '
Bulkhead
I —8 feet
—20' I
srof 5� Hood Canal
Beach
................................................................................................................
Bulkhead E
0 20 SCALE IS APPROXIMATE Embed closest bottom face of `
(Based on site measurements new foundations/rill below
and mapped topography) FS Projection
SCALE(FEET) *Not for Construction
1 inch=20 feet ..................................................................................................................
:
Materials Testing & Consulting,Inc. Tran Residence CAO FIGURE
2118 Black Lake Blvd SW Slope Profile: A—A'
Olympia, WA 98501 188441 East SR-106 3
Belfair, WA 98312
19
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Appendix B. Photos of Site Reconnaissance
via .,�
R.
Photo A. Image of property facing upslope showing deck. stairway and residence. Image
facing Southeast.
a
^r
4j
Photo B. Bulkhead, lower lawn area,beach front and, hood canal. Image facing south.
20
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 185231
Appendix C. Exploration Logs
Grab soil samples were collected from each exploration location by our field geologist during Hand
Auger excavation. Soil samples collected during the field exploration were classified in accordance with
ASTM D2487. All samples were placed in plastic bags to limit moisture loss, labeled, and returned to
our laboratory for further examination and testing.
Exploration logs are shown in full in Appendix C. The explorations were monitored by our field
geologist who examined and classified the materials encountered in accordance with the Unified Soil
Classification System (USCS), obtained representative soil samples, and recorded pertinent information
including soil sample depths, stratigraphy, soil engineering characteristics, and groundwater occurrence.
Upon completion test pits were backfilled with existing native and fill soils tailings.
The stratification lines shown on the individual logs represent the approximate boundaries between soil
types; actual transitions may be either more gradual or more severe. The conditions depicted are for the
date and location indicated only, and it should not necessarily be expected that they are representative of
conditions at other locations and times.
Penetrometer results from DCP testing are shown in Appendix C. During penetrometer advancement,
blow counts were recorded in one-decimeter increments as a thirty-five-pound weight was dropped a
distance of 15 inches. Blow counts were then converted to resistance (kg/cm2), standard penetration
blow counts (N-values), and corresponding soil consistency, as displayed on the logs.
21
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Ml''
Log of Hand Auger HA-1
Tran Residential Property Date Started &1/18
Critical Area Ordinance Date Completed 8/1/18
18841 WA-106 Sampling Method :Grab Samples
BeHair,Washington 98526 Location Anticipated Lower Retairing Wall
MTC Job#:18S231 Logged By :101
m
d >
LL U
d
� = J
a U a DESCRIPTION
0 SILTY SAND with GRAVEL.Dry,roots up to 0.5',gravel up to 2.0"in diameter.Medium BROWN.
Approximately 20.0%Gravel,45.0•5 Sand,35.0'1.Fines
SM
2 SILT.Damp to most,minor roots,minor mottling,some cohesion,silt laminae.GRAYISH BROWN TO
GRAY.
Approximately 001%Gravel,5.0%Sand,95.0%Fines
4 Soil becomes moist and minorly mottled below 4.0 feet BPG.
Minor cohesion observed in soils below 5.0 feet BPG.
MIL
6
Chunks of silt laminae observed in soils below 7.0 feet BPG.
8
Termination Depth:9.0 feet BPG
No groundwater encountered.
Hand Augerterminated on difficult digging conditions.
10
22
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Materials Testing&Consulting, Inc Log of Hand Auger HA-2
2118 Black Lake Blvd SW
Olympia,WA 98512
Tran Residential Property Date Started 8/1/18
Critical Area Ordinance Date Completed :8/1/18
18841 WA-106 Sampling Method Grab Samples
Belfair,Washington 98526 Location Anticipated Upper RW
MTC Job#:18S231 Logged By KH
ILL m m
U a)
C = J
DESCRIPTION Q)
n U
0 Z)
0
SILTY SAND with GRAVEL.Dry,roots up to 0.5',gravel up to 2.0"in diameter.Medium BROWN.
Approximately 20.0%Gravel,45.0%Sand,35.0%Fines
SM
2
SILT.Damp to moist,minor roots,some cohesion.GRAYISH BROWN TO GRAY.
Approximately 0.0%Gravel,5.0%Sand,95.0%Fines
4
ML
6
Minor cohesion observed in soils below 7.0 feet BPG.
8
Termination Depth:9.0 feet BPG
No groundwater encountered
Hand Auger terminated on difficult digging conditions.
10
23
Tran Residential Property-Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
WILDCAT DYNANHC CONE LOG Page 1 of 2
Materials Testing and Consulting
2118 Black Lake Blvd SW PROJECT NUMBER: 18S231
Olympia,WA 98512 DATE STARTED: 08-01-2018
DATE COMPLETED: 08-01-2018
HOLE#: DCP-I
CREW: KH SURFACE ELEVATION: Existing Grade
PROJECT: Tran Residence CAO WATER ON COMPLETION: None encountered
ADDRESS: 18841 E STATE ROUTE 106,BELFAIR,WA HAMMER WEIGHT: 35 lbs.
LOCATION: Anticipated Lower RW CONE AREA: 10 sq.cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm K /cm2 0 50 100 150 N SAND&SILT CLAY
21 93.2 - MEDIUM DENSE VERY STIFF
26 115.4 .........................•••«••• - DENSE HARD
lft 14 62.2 ............•••••• 17 MEDIUM DENSE VERYSTIFF
3 13.3 3 VERYLOOSE SOFT
1 4.4 1 VERYLOOSE VERY SOFT
ti 1 4.4 1 VERYLOOSE VERYSOFT
1 4.4 1 VERYLOOSE VERY SOFT
3 13.3 3 VERYLOOSE SOFT
ti 4 17.8 ••• 5 LOOSE MEDIUM STIFF
1 m 8 35.5 ......•••• 10 LOOSE STIFF
15 57.9 ............•••• 16 MEDIUM DENSE VERYSTIFF
4t4 15 57.9 ............•••• 16 MEDIUM DENSE VERYSTIFF
17 65.6 ..................• 18 MEDIUM DENSE VERYSTIFF
14 54.0 ............••• 15 MEDIUM DENSE STIFF
5 ft 16 61.8 ............••••• 17 MEDIUM DENSE VERY STIFF
10 38.6 ......••••• 11 MEDIUM DENSE STIFF
10 38.6 ......••••• 11 MEDIUM DENSE STIFF
6 ft 8 30.9 ......•• 8 LOOSE MEDIUM STIFF
10 38.6 ......••••• 11 MEDIUM DENSE STIFF
- 2 m 8 30.9 ......•• 8 LOOSE MEDIUM STIFF
- 7 ft 8 27.4 ......• 7 LOOSE MEDIUM STIFF
- 8 27.4 ......• 7 LOOSE MEDIUM STIFF
- 7 23.9 •••• 6 LOOSE MEDIUM STIFF
8 ft 7 23.9 •••• 6 LOOSE MEDIUM STIFF
10 34.2 ......••• 9 LOOSE STIFF
8 27.4 ......• 7 LOOSE MEDIUM STIFF
9 ft 10 34.2 ......••• 9 LOOSE STIFF
11 37.6 ......•••• 10 LOOSE STIFF
13 44.5 ......•••••• 12 MEDIUM DENSE STIFF
m loft 13 44.5 ••• 12 MEDIUM DENSE STIFF
12 36.7 ......•••• 10 LOOSE STIFF
12 36.7 ......•••• 10 LOOSE STIFF
14 42.8 ......•••••• 12 MEDIUM DENSE STIFF
11 11 17 52.0 14 MEDIUM DENSE STIFF
18 55.1 15 MEDIUM DENSE STIFF
15 45.9 13 MEDIUM DENSE STIFF
12 t t 16 49.0 13 MEDIUM DENSE STIFF
14 42.8 ......•••••• 12 MEDIUM DENSE STIFF
16 49.0 ............•• 13 MEDIUM DENSE STIFF
- 4 m 13 ft 15 45.9 ............• 13 MEDIUM DENSE STIFF
WLMAT.XLS
24
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
HOLE#:DCP-1 WILDCAT DYNAMIC CONE LOG Page 2of 2
PROJECT:Tran Residence CAO PROJECT NUMBER: 18S231
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm= 0 50 100 150 N SAND&SILT CLAY
- 19 52.6 •............•• 15 MEDIUM DENSE STIFF
- 20 55.4 ............•••• 15 MEDIUM DENSE STIFF
14 ft 21 58.2 ...........•••• 16 MEDIUM DENSE VERYSTIFF
- 26 72.0 ..................•• 20 MEDIUM DENSE VERYSTIFF
- 27 74.8 ..................••• 21 MEDIUM DENSE VERYSTIFF
- 15 ft 36 99.7 ........................•••• - MEDIUM DENSE VERYSTIFF
- 39 108.0 ..............................• - MEDIUM DENSE VERYSTIFF
- 43 119.1 ••••••.......................•••• - DENSE HARD
- 16 ft 50 138.5 ........................................ - DENSE HARD
- 5m
17ft
- 181i
19 tit
6m
2011
21 ft
22 ft
7m 23ft
24 Ii
2;It
2011
27 ft
?8 It
29 I(
9111
Tran Residential Property-Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
W-MDCAT DYNAMIC CONE LOG Page 1 of 2
Materials Testing and Consulting
2118 Black Lake Blvd SW PROJECT NUMBER: 18S231
Olympia,WA 98512 DATE STARTED: 08-01-2018
DATE COMPLETED: 08-01-2018
HOLE#: DCP-2
CREW: KH SURFACE ELEVATION: Existing Grade
PROJECT:Tran Residence CAD WATER ON COMPLETION: None encountered
ADDRESS: 18841 ESTATE ROUTE 106,BELFAIR,WA HAMMERWEIGHT: 35lbs.
LOCATION: Anticipated UpperRW CONEAREA: 10 sq.Cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm? 0 50 100 150 N' SAND&SILT CLAY
- 22 97.7 ........................•••• MEDIUM DENSE VERY STIFF
- 37 164.3 ............................................. DENSE HARD
- 1 ft 39 173.2 ............................................. DENSE HARD
- 32 142.1 ......................................... _ DENSE HARD
- 26 115.4 ................................• - DENSE HARD
- 2 8 15 66.6 ..................• 19 MEDIUM DENSE VERY STIFF
- 9 40.0 ......••••• I MEDIUM DENSE STIFF
4 17.8 ••• 5 LOOSE MEDIUM STIFF
li 5 22.2 •••• 6 LOOSE MEDIUM STIFF
1 m 4 17.8 ••• 5 LOOSE MEDIUM STIFF
3 11.6 3 VERYLOOSE SOFT
4 Q 5 19.3 ••• 5 LOOSE MEDIUM STIFF
7 27.0 ......• 7 LOOSE MEDIUM STIFF
10 38.6 ......••••• 11 MEDIUM DENSE STIFF
5 i1 6 23.2 •••• 6 LOOSE MEDIUM STIFF
6 23.2 •••• 6 LOOSE MEDIUM STIFF
7 27.0 ......• 7 LOOSE MEDIUM STIFF
6 ft 8 30.9 ......•• 8 LOOSE MEDIUM STIFF
5 19.3 ••• 5 LOOSE MEDIUM STIFF
- 2 m 8 30.9 ......•• 8 LOOSE MEDIUM STIFF
- 7 ft 7 23.9 •••• 6 LOOSE MEDIUM STIFF
- 9 30.8 ......•• 8 LOOSE MEDIUM STIFF
- 10 34.2 ......••• 9 LOOSE STIFF
- R fl 12 41.0 ......••••• 11 MEDIUM DENSE STIFF
- 14 47.9 ............• 13 MEDIUM DENSE STIFF
- 12 41.0 ......••••• 11 MEDIUM DENSE STIFF
- 91i 11 37.6 ......•••• 10 LOOSE . STIFF
- 16 54.7 ............••• 15 MEDIUM DENSE STIFF
17 58.1 ............•••• 16 MEDIUM DENSE VERY STIFF
m l i)Il 18 61.6 ••••••••••••••••• 17 MEDIUM DENSE VERY STIFF
17 52.0 ............••• 14 MEDIUM DENSE STIFF
19 58.1 ............•••• 16 MEDIUM DENSE VERY STIFF
16 49.0 ............•• 13 MEDIUM DENSE STIFF
11 ft 15 45.9 ............• 13 MEDIUM DENSE STIFF
14 42.8 ......•••••• 12 MEDIUM DENSE STIFF
19 58.1 ............•••• 16 MEDIUM DENSE VERYSTIFF
12 ft 15 45.9 ............• 13 MEDIUM DENSE STIFF
17 52.0 ............••• 14 MEDIUM DENSE STIFF
18 55.1 ............••• 15 MEDIUM DENSE STIFF
4 m 13 ft 20 61.2 ............••••• 17 MEDIUM DENSE VERY STIFF
WILDCATXLS
26
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
HOLE#:DCP-2 WILDCAT DYNAMIC CONE LOG Page 2of 2
PROJECT:Tran Residence CAO PROJECT NUMBER: 18S231
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm? 0 50 100 150 N SAND&SILT CLAY
- 23 63.7 •............••••• 18 MEDIUM DENSE VERYSTIFF
19 52.6 ............••• 15 MEDIUM DENSE STIFF
- 14 ft 20 55.4 ............•••• 15 MEDIUM DENSE STIFF
- 26 72.0 ..................•• 20 MEDIUM DENSE VERYSTIFF
26 72.0 ..................•• 20 MEDIUM DENSE VERYSTIFF
- 15 ft 24 66.5 ..................• 18 MEDIUM DENSE VERYSTIFF
- 25 69.3 ..................•• 19 MEDIUM DENSE VERYSTIFF
- 24 66.5 ..................• 18 MEDIUM DENSE VERYSTIFF
- 16 ft 29 80.3 ..................••••• 22 MEDIUM DENSE VERYSTIFF
- 5 m 35 97.0 ........................•••• - MEDIUM DENSE VERYSTIFF
37 94.0 ........................••• MEDIUM DENSE VERYSTIFF
- 17 ft 39 99.1 ........................•••• - MEDIUM DENSE VERYSTIFF
- 44 111.8 ...............................• - DENSE HARD
- 44 111.8 ...............................• - DENSE HARD
- 18 ft 50 127.0 ...................................• DENSE HARD
19ft
6m
20 ft
21ft
22 ft
7m 2',it
24 R
15(i
26 ft
- 8m
27 ft
28 ft
29 ft
9m
WLDCATALS
27
Tran Residential Property—Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Appendix D. Laboratory Test Results
Laboratory tests were conducted on several representative soil samples to better identify the soil
classification of the units encountered and to evaluate the material's general physical properties and
engineering characteristics. A brief description of the tests performed for this study is provided below.
The results of laboratory tests performed on specific samples are provided at the appropriate sample
depths on the individual boring logs. However, it is important to note that these test results may not
accurately represent in situ soil conditions. All of our recommendations are based on our interpretation
of these test results and their use in guiding our engineering judgment. MTC cannot be responsible for
the interpretation of these data by others.
Soil samples for this project will be retained for a period of 3 months following completion of this report,
unless we are otherwise directed in writing.
SOIL CLASSIFICATION
Soil samples were visually examined in the field by our representative at the time they were obtained.
They were subsequently packaged and returned to our laboratory where they were re-examined and the
original description checked and verified or modified. With the help of information obtained from the
other classification tests, described below, the samples were described in general accordance with ASTM
Standard D2487. The resulting descriptions are provided at the appropriate locations on the individual
exploration logs and are qualitative only.
GRAIN-SIZE DISTRIBUTION
Grain-size distribution analyses were conducted in general accordance with ASTM Standard D422 on
representative soil samples to determine the grain-size distribution of the on-site soil. The information
gained from these analyses allows us to provide a description and classification of the in-place materials.
In turn, this information helps us to understand engineering properties of the soil and thus how the in-
place materials will react to conditions such as heavy seepage, traffic action, loading, potential
liquefaction,and so forth. The results are presented in this Appendix.
28
Tran Residential Property-Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
Sieve Report
Project.Tran Residence Critical Area Ordinance Date Received:l l-Sep-18 ASTM D-2487 Unified Soils Classification System
Project#: 18S231 Sampled By:KH L,Silt
Client.John Dalberg Date Tested:13-Sep-18 Sample Color:
Source:HA1 @-6 Tested By:JE Gay ACCREDITED
G'Mra T•.L.YRM
Sam e#:S18 2075
ASTM D-2216 ASTM D-2419 ASTM D-4318 ASTM W5821
D,,;=0.004 mm %Gravel=0.0% Cceff.of Curvature,Cc=1.50
Specifications DOo;=0.008 mm %Sand=1.2% Cceff.of Uniformity,Cc=6.00
No Spas Dp,1=0,011 mm %Silt&Clay=98.8% Fineness Modulus=0.02
S ample Meets Specs?N/A Dpot=0.023 mm Liquid Limit=36.4% Plastic Limit=25.68/6
Dt,u=0.038 mm Plasticity Index=10.8% Moisture%,as sampled=28.3%
D(6o)=0.046 nun Sand Equivalent=n/a Req'd Sand Equivalent=P
D„o;=0.068 mm Fracture%,I Face=n/a Req'd Fracture%,1 Face=r
Dust Ratio= # Fracture%2+Faces=n/a R 'd Fracture%,2+Faces=
ASTM C-136,ASTM D-6913
Actual Interpolated
Gran Si.DislnWlim
Cumulative Cumulative
Sieve Size Percent Percent Specs Specs
US Metric Passin Passing Ma: Min
12.00" 300.00 100% 100.0% 0.0'/o I IIII:I I ;'III ! iit 't�'ti}II I it
I y,. I t i
10.001, 250.00 1000/0 100.0% 0.0e/ i ,lii,ii I !iiiliil i Ilii i i illi,• .�i,li
8,00" 200.00 1000/a 100.0% 0.Oa/o sna
6.00^ 150.00 loos/ 100.0% o.oe/ i�i�iil l ' I till ! !i iii ii�! i
4.00" 100.00 100% loo.o^/o 0.0% II'ittt ! `IN H:i Iltt
4 - I
ern _}___ -+-i7i41++- -i -S enos
3.00" 75.00 100% 100.0% 0.0% ; j j illl l i I !liiil i i i ?Hil l i I
2.50" 63.00 100% 100.0% 0.00/0illtll�' I i i li11 E ittii
illlli
2.00" 50.00 100% 100.00/0 0.0"/o r� �-_!il�ill _Ittit j _7__ LI: „. � i rnws
•: I i 1
1.75" 45.00 100% 100.0% 0.oe/ i iliiiii ! �i ilEEi
;III II.•
1.50" 37.50 100% 100.00/0 0.0% I 'I " I
I•I I
I iHIM i illllll i :::: Iiiil° 3H '
,ii• • I ;
1.25" 31.50 100% 100.00/0 0.00/0T -j j(i III i;
1.00" 25.00 100% 100.0% 0.0% .F I"li!I I lilt li I i till!
3/4" 19.00 100% 100.00/0 0.00/0 >° tiilitt IL'iit:' I^ ii :lit
-t rirt1
--- +
t 1
5/8" 16.00 100% 100.0% 0.00/1 r i--: HICC* - I t I E I I II'II! '
1/2" 12.50 100% 100.00/0 0.00/ !NH
1 I i wi
iii f 1 t 'il�ll� I "iiiii
3/8" 9.50 100"/0 100.0% 0.0% ,as T--;il l i 1 -�-.i1• 1
1/4" 6.30 room t00.00/ o.oei I ;lilt i i iiiii i itIii'•i 1 i!i it I
i i y;tilil i t
#4 4.75 1000/0 1000/0 100.0% o.o^/ i It:ittt I i IIIII I I ! IillllE I i illlli!I I ^iiiii i i
#8 2.36 100% 100.0% 0.00/ -- 'F-+----fffl::-1 I i -- 11 lilt,
#10 2.00 100% 1000/0 B 100.0% o.o% I I I! i i i� ••;
#16 1.18 100% 100.00/ 0.00/ i l i i III I i1; 11 i a 1
#20 0.850 100% 100% 100.0% 0.0% -«- i.i �_� -- -�t- '- ; zaox
i i il• i i AIM I I I digit'i
#30 o.6ao 100% 100.00/0 0.o"i i iiii ! I'tiiit Ili
ll
#40 0.425 100% 100% 100.00/0 0.0%
it
Itijµ'
t} tnox
#50 0.300 99% 100.0% 0.0% , III i I
Hit
Ili i liiiiili i ilrl!
#60 0.250 990/0 99% 100.00/0 0.oai illllili i Illillil i iiiii!!I i Itiiiili i ;iiiifl i
#80 0.180 99% 990/0 100.00/0 0.00/ 1 mm o.• o.ao omo�
#100 0.150 99"/0 99% 100.01/. 0.000/0
#140 0.106 99% 100.0% 0.01/6 Pp-5e"t0aot
#170 0.090 99"/0 100.01% 0.00/0
#200 0,075 98.8% 1 98.8% 100.0% 0.00/1 . se"0s�: �.-t. vim• ��nnsP•d �,.�s"""s�dn
CWrgN Speam Enain n a Tech l Services PS,199&98
29
Tran Residential Property-Critical Area Ordinance Materials Testing&Consulting,Inc.
September 21,2018 18S231
ASTM D4318 - Liquid Limit, Plastic Limit and Plasticity Index of Soils
Project: Tran Residence Critical Area( Date Received: 11-Sep-18 Unified Soils Classification System,AST-NI D-2487
Project#: 18S231 Sampled By: KH L,Silt
Client: John Dalberg Date Tested: 13-Sep-18 Sample Color
Source: HAI @-6' Tested By: JE Gray
Sans le#: S18-2075
li uid limit Determination
I'I #2 #3 F4
Weight of Wet Soils+Pan: 15.92 14.58 29.06
Weight of Dry Soils+Pan: 12.42 11.15 21.48
Weight of Pan: 1.55 1.55 1.55
Weight of Dry Soils: 10.87 9.60 1293 liquid limit @ 25 Blows: 36.4%
Weight of Moisture: 3.50 3.43 7.58 Plastic limit: 25.6%
%Moisture: 32.2% 35.7% 38.0% Plasticity Index,1p: 10.8%
N n In he r o f 111401%1: 33 28 21
Plastic limit Determination
Weight of Wet Soils+Pan: 4.01 3.41
Weight of Dry Soils+Pan: 3.51 3.03
Weight of Pan: L55 1.55
Weight of Dry Soils: 1.96 1.Fs ACCREDITED
Weight of Moisture: 0.50 0.38 eem aroc,xso,.�usoxtueea
%Moisture: 25.5% 25.7
01
60.0% -------------. - - ----------------- Plasticity Chart Liquid Limit
=' 45%
I
70.0% ,___------ ----
---------;----------;----------;-------------------;----------r---------, r=------------;--------- 40% ------------------- -- --
60.0% , ------- °- ------------------- ------- 35% - --
r,' !A' e!
X
-------- - -
,
,
+CH or H r + + i 25% } + I T I T11-+-1
Y i .
,
, ,
as ---------4--------------------'--------- ----------------- ------- ------- ----------------------------
MH or OH
a ;
�- t s% F f + ++a+1
zo.o% CL or Q ,
10.0% ----- ------: ----- r --------� t , � i L
0.0%
0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 110D% 0%
10 100
Liquid Limit Number of Blows,"N"
30