HomeMy WebLinkAboutGEO2012-00027 - GEO Geological Review - 5/2/2012 60 Percent Design Report
Geotechnical Engineering Services
Potlatch Transmission Lines
North Bay Crossing
Mason County, Washington
for
Tacoma Public Utilities
May 2, 2012
Geotechnical Engineering Services
Potlatch Transmission Lines i
North Bay Crossing
Mason County, Washington
File No. 4682-028-02
May 2,2012
Prepared for:
Tacoma Public Utilities f
3628 South 351h Street
Tacoma,Washington 98409-3192
Attention: Pat Leach, PE,SE
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Prepared by: 4 of
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GeoEn ineer . Inc.
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11.01 South Fawcett Avenue, Suite 200
Tacoma, Washington 98402 1
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253.383.49
SSjO`AL
Morgan McArthur, PE
Gectechnical Engineer
David S. Phelps, PE
Principal
WDSP.tt
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Table of Contents
INTRODUCTION ..........................................................................................................................................1
PROJECT UNDERSTANDING......................................................................................................................1
PURPOSE AND SCOPE OF SERVICES.......................................................................................................1
PhaseI....................................................................................................................................................2
PhaseII...................................................................................................................................................2
SITECONDITIONS.......................................................................................................................................3
SurfaceConditions.................................................................................................................................3
GeologyReview......................................................................................................................................3
Subsurface Explorations........................................................................................................................4
SubsurfaceConditions ..........................................................................................................................4
General ............................................................................................................................................4
Ili Proposed East Dead-End Tower Location......................................................................................4
Proposed In-Water Tower Location................................................................................................4
Proposed West Dead-End Tower Location.....................................................................................4
Groundwater,Artesian Groundwater and Soil Heaving.......................................................................5
TidalVariation ........................................................................................................................................5
ENGINEERING AND ANALYSIS..................................................................................................................5
Soil Profile and Soil Strength Parameters............................................................................................5
Seismic Design Considerations.............................................................................................................6
Seismic Design Approach and Discussion ....................................................................................6
LiquefactionAnalysis......................................................................................................................7
Recommended Seismic Design Parameters.................................................................................7
SlopeStabilityAnalysis..........................................................................................................................8
AnalysisMethodology.....................................................................................................................8
SlopeStability Analysis Results......................................................................................................8
CONCLUSIONS............................................................................................................................................8
RECOMMENDATIONS................................................................................................................................9
Upland Dead-End Tower Areas..............................................................................................................9
Site Preparation and General Earthwork.......................................................................................9
WetWeather Earthwork................................................................................................................10
StructuralFill Materials.................................................................................................................11
Structural Fill Placement and Compaction..................................................................................12
DrilledShafts.................................................................................................................................12
In-Water Tower Area.............................................................................................................................13
DrivenPiles....................................................................................................................................13
PileAnchors..........................................................................................................................................15
LIMITATIONS...........................................................................................................................................16
REFERENCES.......................................................................................................................................... 16
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LIST OF FIGURES
Figure 1. Vicinity Map
Figure 2. Site Plan
Figure 3. Cross Section A-A'
Figure 4. Map-Based Response Spectra
Figure 5. Recommended Response Spectra
Figures 6 through 11. LPILE Analysis
Figures 12 through 21. LRFD Drilled Shaft Analysis
APPENDICES
Appendix A.Subsurface Explorations and Laboratory Testing
Figure A-1. Key to Exploration Logs
Figures A-2 through A-7. Log of Borings
Figure A-8. Sieve Analysis Results
Appendix B. Report Limitations and Guidelines for Use
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INTRODUCTION
This report presents the results of our geotechnical engineering services for Phase II design of the
North Bay Crossing portion of Tacoma Public Utilities' (TPU) Potlatch Transmission Lines project.
This report also re-presents and updates information previously provided in our Phase I report,
dated November 2, 2009.
The project site is located near the head of North Bay, in Mason County, Washington, as shown on
the Vicinity Map in Figure 1. Our services have been provided in accordance with our agreements
with Electric Power Systems, Inc. (EPS)dated May 11, 2009 and December 5, 2011.
This report provides the results of subsurface explorations completed at the site and geotechnical
recommendations for driven pile and drilled shaft foundation support of the new mid-bay and dead-
end towers described below.
PROJECT UNDERSTANDING
The project design team includes representatives of TPU, EPS, David Evans Associates (DEA),
BergerABAM and GeoEngineers, Inc. As part of Phase I, the design team identified and evaluated
options for replacing the existing North Bay crossing, which is supported by lattice towers
constructed in 1925. The current configuration comprises two single-circuit parallel crossings with
three spans of about 1,200 feet each, and utilizes two in-water foundation landings and two
upland foundation landings for each circuit. Each circuit includes three conductors. Existing in-
water foundations are supported on timber piles. We understand the western set of in-water
foundations have tilted such that the two towers lean toward one another. The timing and rate of
foundation tilting is unknown.
We understand that the planned replacement will reconfigure the three-span crossing into a two-
span crossing by replacing the four in-water towers with a single tower near the middle of the
crossing. This tower will be approximately 170 feet tall, constructed of tubular steel and will carry
both circuits. The mid-crossing tower will be supported on a concrete platform founded on four
driven steel pipe piles. The two existing in-water towers will be removed as part of this project.
New dead-end structures will also be installed on either side of the bay to replace the existing
tangent towers, which will also be removed. Two alternatives are currently under consideration for
the dead-end structures: 1)two tubular steel structures, each of which will carry one, 3-conductor
circuit or 2) six tubular steel structures, each of which will carry a single conductor. The dead-end
structures will be founded on drilled shafts and will be self-supporting without utilizing guys to
resist loading.
PURPOSE AND SCOPE OF SERVICES
The purpose of our services is to explore subsurface soil conditions and review available
subsurface information as a basis for developing geotechnical recommendations for tower
foundation support. Our scope of services includes:
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Phase I
1. Preparing a Health and Safety Plan for use by our personnel during over-water exploration
work.
2. Contacting the Washington Utilities Coordinating Council (UTC), "One Call" service to locate
utilities near the in-water area and coordinating with TPU to confirm boring locations, clearance
requirements and minimum approach distance to energized conductors.
3. Drilling four borings to depths ranging from approximately 53 feet to 95 feet below mudline
(BMQ.
4. Completing laboratory tests on selected samples recovered from the borings. Laboratory tests
consist of percent fines and moisture/density relationship determinations.
5. Characterizing the subsurface conditions at the site based on results of our review,the borings,
laboratory testing and preparing a schematic subsurface profile.
6. Providing recommendations for seismic design considerations including seismic design criteria
consistent with American Society of Civil Engineers (ASCE) 113 - Substation Structure Design
Guide, the 2009 edition of the International Building Code (IBC) and the California State Lands
Commission Marine Oil Terminal Engineering and Maintenance Standards (MOTEMS). We also
provide an evaluation of the liquefaction potential of site soils.
7. Developing recommendations for in-water tower foundation design and installation. We
provide ultimate downward and uplift capacities for selected types/sizes of driven piles.
8. Discussing driven pile foundation construction considerations based on the results of our
subsurface explorations and our experience.
9. Providing soil parameters applicable for lateral pile and lateral shaft capacity analysis using
LPILE and Deep Foundation System Analysis Program (DFSAP)software.
Phase II
10. Preparing a job hazard analysis and geotechnical work plan for use by our personnel during
upland exploration work.
11. Contacting Washington UTC "One Call" service to locate utilities in the upland area and
coordinating with TPU to confirm boring locations, clearance requirements and minimum
approach distance to energized conductors.
12. Drilling two borings each to a depth of approximately 70 feet below ground surface (bgs).
GeoEngineers subcontracted the drilling equipment and operator.
13. Completing laboratory tests on selected samples recovered from the borings, including grain-
size distribution and percent fines determination.
14. Characterizing the subsurface conditions at the site based on results of the field explorations
and laboratory testing programs and preparing a summary subsurface cross section,
incorporating the findings of the Phase I and Phase II investigations.
15. Providing new (land-based) and updated (in-water) LPILE and DFSAP parameters for use in
lateral pile/shaft analyses and development of seismic soil springs by the structural engineers.
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16. Developing recommendations for axial capacity of land-based shaft foundations. These
recommendations are limited to two shaft foundation sizes.
17. Evaluating and discussing the possibility of the following, resulting from earthquake ground
motions: 1) slope instability, 2) liquefaction and 3) surface rupture. This includes limit-
equilibrium analysis of slope stability for the upland area.
18. Discussing drilled shaft foundation construction concerns based on the results of subsurface
explorations and experience.
19. Preparing 60%, 90% and 100% design reports presenting the geotechnical conclusions and
recommendations along with supporting field and laboratory data. The 90% and 100% design
reports will incorporate interdisciplinary review comments and outside review comments,
respectively.
20. Performing a plan review of 60%, 90%and 100%civil and structural plans and specifications.
21. Providing geotechnical consultation to the project team during the design process.
SITE CONDITIONS
Surface Conditions
Our understanding of surface conditions and topography is based on review of information
provided and our observations during site exploration activities. The ground surface or "mudline"
along the in-bay portion of the North Bay crossing alignment is relatively shallow. Based on
reported tides available from online sources and our observations during site exploration, mudline
elevation generally varies from about -2 to -3 feet mean lower low water (MLLW) adjacent to the
existing towers and from about -4 to -5 feet MLLW near the center of the North Bay Crossing.
Upland slopes are generally on the order of about 8H:1V(horizontal to vertical)on the western side
of the bay and about 5H:1V on the eastern side of the bay. Vegetation in the vicinity of the
proposed upland towers generally consists of grass and brush, and appears to be periodically
mowed.
Geology Review
The geologic information we reviewed for the project vicinity includes the Washington State
Department of Natural Resources (DNR) Geologic Map of the Belfair 7.5-minute Quadrangle,
Mason, Kitsap, and Pierce Counties, Washington, which provides elevations relative to the National
Geodetic Vertical Datum of 1929 (NGVD29). This map identifies the soils surrounding the bay as
beach deposits (Qb and Qob) and marsh deposits(Qm). Beach deposits are described as a mixture
of sand, pebbles, cobbles, silt and clay in a loose/soft condition. Marsh deposits are described as
organic sediment and clay, silt and sand in a loose/soft condition. This map does not identify or
describe soils present in the center of North Bay.
In the upland areas of the transmission line crossing, soils are mapped as consisting of glacial till
deposits (Qgt), which are described as an unsorted, unstratified mix of clay, silt, sand and gravel in
a very dense condition. Advance outwash deposits (Qga) are also mapped in the upland areas.
Advance outwash deposits are described as pebble to cobble-sized gravel and sand with layers and
lenses of silt and clay in a dense to very dense condition. Portions of the western and eastern
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slopes are mapped as recessional lake-marginal outwash deposits (Qgol), which are described as
gravel and sand, but may locally include zones of silt, especially near the base of the unit. In the
vicinity of the existing crossing, the recessional lake-marginal outwash deposits are mapped from
about Elevation 10 feet to 50 feet (NGVD29) on the western slope and about Elevation 10 feet to
120 feet(NGVD29)on the eastern slope.
Subsurface Explorations
We explored subsurface conditions at the site by advancing four over-water borings from the deck
of a barge and two on-land borings at the approximate locations shown on Figure 2. The over-
water borings were completed between August 17 and 21, 2009 and the on-land borings were
completed December 29 and 30, 2011. Details of our subsurface explorations, including summary
boring logs and laboratory test results are presented in Appendix A.
Subsurface Conditions
General
A schematic subsurface profile showing our interpretation of subsurface conditions and the extent
of the major soil units is presented on Figure 3. Although not encountered in our explorations,
cobbles and boulders may also be present in many of the soil units present in the project area.
Proposed East Dead-End Tower Location
We characterize the materials encountered in boring B-4 into three units: 1) fill and reworked
native soil, 2) recessional lake-marginal outwash and 3) advance outwash. At our exploration
location, the fill and reworked native soil comprised crushed rock gravel and very stiff sandy silt,
extending to about 2.5 feet bgs. We interpret this material to be associated with the gravel-
surfaced road through which our exploration was advanced. The recessional lake-marginal
outwash comprised loose to medium dense sand with silt and varying gravel content, extending
from about 2.5 feet bgs to 13 feet bgs. The advance outwash generally comprised dense to very
dense silty sand and sand with silt, extending from about 13 feet bgs to the full depth explored.
We interpret only the advance outwash unit to have been glacially consolidated.
Proposed In-Water Tower Location
We characterize the materials encountered in our over-water explorations (borings B-1 through B-3)
into four units: 1) marine/alluvial deposits, 2)glaciolacustrine silt, 3) glacial till and 4) advance
outwash. At our exploration locations, the marine/alluvial deposits typically comprise very soft/
very loose to soft/loose sandy silt and silty sand with organic material and shell fragments. The
glaciolacustrine silt generally consists of medium stiff sandy silt or silt with clay and sand. The
glacial till typically comprises very dense sand and gravel with varying amounts of silt. The advance
outwash generally consists of very dense sand with silt or silty sand with interbedded zones of hard
sandy silt and silt with sand. The four soil units are noted separately in our boring logs. We
interpret both the glacial till unit and advance outwash unit to have been glacially consolidated.
Proposed West Dead-End Tower Location
We characterize the materials encountered in boring B-5 into two units: 1) glacial till and
2) advance outwash. At our exploration location, the glacial till comprised a layer of dense silty
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gravel with sand, about 3.5 feet thick, overlying very dense silty sand with gravel, extending to
about 26 feet bgs. We interpret the silty gravel with sand to be the weathered portion of the glacial
till soil. The advance outwash generally comprised very dense sand with silt, extending from about
26 feet bgs to the full depth explored. We interpret the glacial till and advance outwash to have
been glacially consolidated.
Groundwater,Artesian Groundwater and Soil Heaving
In the upland areas, borings B-4 and B-5 encountered shallow perched groundwater in the
recessional lake-marginal outwash and glacial till units, each at depths of about 3 to 3.5 feet bgs.
We interpret this perched groundwater to be associated with precipitation events at the time of our
upland explorations. Based on soil conditions observed in these explorations and review of well
logs in the area, we interpret the upland regional groundwater table to be within the advance
outwash unit, at a depth of about 40 to 45 feet bgs.
Soils encountered in our over-water explorations (borings B-1 through B-3) are below Puget Sound
tidal waters except for very near surface soils during low tide. During drilling of B-2, at a depth of
about 85 feet to 90 feet bml, water flowed out of the top of the auger, which was about 12 feet
above mudline at the time. We interpret this condition as artesian groundwater. We anticipate
that artesian groundwater may be present within confined, permeable layers of the advance
outwash unit. We do not expect that artesian conditions are present within the glacial till unit.
Heaving (flowing) soil conditions were encountered in uncemented portions of the glacial till unit
and advance outwash unit while advancing some of our explorations. Heaving conditions are
commonly encountered in saturated, uncemented, sandy soils where hydrostatic pressure outside
the auger is greater than the pressure inside the auger. The soil near the tip of the auger is forced
upward into the auger by the unbalanced pressures. Artesian groundwater may cause heaving
conditions; however, heaving conditions do not necessarily indicate artesian groundwater. Where
heaving conditions are encountered, drillers typically add water or drilling fluid inside the auger or
casing to balance the pressures.
Tidal Variation
Based on tidal information available online, tidal variations in North Bay can range up to about
20 feet. During our exploration activities, the drilling barge was periodically grounded during low
tides.
ENGINEERING AND ANALYSIS
Soil Profile and Soil Strength Parameters
We developed the soil strength parameters and soil profile presented in Tables 1 through 3 for use
in design at the project site. The soil profile depth ranges provided are in feet bgs or feet bml. The
soil parameters are based on our exploration and laboratory test results, published strength values
for similar soils, our review and our experience.
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TABLE 1. DESIGN SOIL PARAMETERS - EAST DEAD-END TOWER AREA
Soil Unit Weight Shear Strength
Soil Unit Depth Range (pcf) Parameters
(feet bgs)
Total Effective �(deg) cohesion(psf]
Recessional Lake-Marginal 0-13 120 60 32 0
Outwash
Advance Outwash Below 13 120 60 36 200
TABLE 2. DESIGN SOIL PARAMETERS - IN-WATER TOWER AREA
Soil Unit Weight Shear Strength Parameters
Soil Unit Depth Range(feet bmi) (pcf) Static Liquefied
Total Effective �(deg) c(psf) �(deg) c(psf)
Marine/Alluvial Deposits 0-28 100 40 28 0 7 0
Glaciolacustrine Silt 28-33 110 50 0 1,200 0 800
Glacial Till 33-63 125 65 40 500 40 500
Advance Outwash Below 63 120 60 36 200 36 200
TABLE 3. DESIGN SOIL PARAMETERS - WEST DEAD-END TOWER AREA
Soil Unit Weight Shear Strength
Soil Unit Depth Range (pcf) Parameters
(feet bgs)
Total Effective �(deg) cohesion(psf)
Glacial Till 0-26 125 65 40 500
Advance Outwash Below 26 120 60 36 200
Seismic Design Considerations
Seismic Design Approach and Discussion
Based on design team meetings, we understand the crossing will be designed using two seismic
approaches. The upland structures and the portion of the in-water tower above the foundation
attachment will be designed using the simplified force-based procedure outlined in ASCE Manual
113. The in-water tower and foundation combination will be designed using a performance-based
approach in general accordance with the MOTEMS.
This seismic design approach requires evaluating three nominal earthquake levels. The ASCE 113
method uses a design level consistent with 2/3 of the 2,475-year return period earthquake. The
MOTEMS approach uses two hazard levels: 1) the Operating Level Earthquake (OLE), which is
based on the 72-year return period earthquake and 2) the Contingency Level Earthquake (CLE),
which is based on an envelope of 2/3 of the 2,475-year return period event and the 475-year
return period event.
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The crossing is underlain by soils we anticipate to have varying responses to earthquake forces.
During seismic shaking stiffer soil profile in the upland area will result in a significantly different
ground surface response than the less stiff soil profile present beneath North Bay. The soil profile
beneath North Bay is also characterized by a sharp contact between loose/soft marine sediments
and very dense/hard glacially consolidated soils. Because the foundations for the in-water tower
will be installed through the marine sediments and into the glacially consolidated soils, it is difficult
to understand which soil response will control the structure response without a detailed model of
soil-structure interaction. In order to provide a conservative design without detailed modeling, the
OLE and CLE response spectra for the in-water structure envelope the map-based responses for
site classes C, D and E.
Liquefaction Analysis
UPLAND DEAD-END TOWER AREAS
Based on our explorations, the soils present below the regional groundwater table in the upland
areas are generally dense to very dense and glacially consolidated. We do not anticipate a risk of
liquefaction in the areas of the upland dead-end towers.
IN-WATER TOWER AREA
We evaluated the liquefaction potential of site soils for the OLE and CLE design level earthquakes
using simplified methods (Seed et. al, 2003 and Idriss and Boulanger, 2008), which are based on
comparing the cyclic resistance ratio (CRR)of a soil layer(the cyclic shear stress required to cause
liquefaction) to the cyclic stress ratio (CSR) induced by an earthquake. The factor of safety (FS)
against liquefaction is determined by dividing the CRR by the CSR. In our analysis, we used an
earthquake magnitude of 7.0 and site-modified peak ground acceleration (PGA) of 0.36 to
represent the CLE design level earthquake, and an earthquake magnitude of 7.0 and site-modified
PGA of 0.25 to represent the OLE design level earthquake.
Based on our analysis, there is a risk of liquefaction and soil strength loss in the soils beneath
North Bay during both the OLE and CLE events. Our calculations indicate a risk of liquefaction in
the marine/alluvial deposits and a risk of partial soil strength loss in the glaciolacustrine silt unit.
We estimate liquefaction-induced settlements of about 6 to 16 inches at the mudline and
differential settlements on the order of half this amount for both design level earthquakes.
Recommended Seismic Design Parameters
UPLAND TOWER AREAS
We used map-based methods to develop seismic design parameters for use in structural design of
the upland towers, in general accordance with ASCE 113. The recommended seismic design
parameters for the upland towers are shown in Table 4.
TABLE 4. RECOMMENDED SEISMIC DESIGN PARAMETERS- UPLAND DEAD-END TOWER AREAS
Seismic Design Parameters
Site Class C
Mapped Spectral Response Acceleration at Short Period(Ss) 1.35g
Mapped Spectral Response Acceleration at 1 Second Period(Si) 0.48g
Design Peak Ground Acceleration(PGA) 0.38Q
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Seismic Design Parameters
Design Spectral Acceleration at 0.2 second period 0.90g
Design Spectral Acceleration at 1.0 second period OA2g
IN-WATER TOWER AREA
We used map-based methods to develop seismic design parameters for use in structural design of
the in-water tower, in general accordance with MOTEMS. Figure 4 shows the map-based response
spectra at the in-water tower location for site classes C, D and E and each of the design seismic
events. In order to envelope the potential responses of the different site classes and seismic
events, we recommend the OLE and CLE response spectra shown on Figure 5.
Slope Stability Analysis
Analysis Methodology
We performed slope stability analyses using the computer program SLOPE/W (GEO-SLOPE
International, Ltd., 2007). SLOPE/W evaluates the stability of numerous trial shear surfaces using
a vertical slice limit-equilibrium method. This method compares the ratio of forces and moments
driving slope movement versus forces and moments resisting slope movement for each trial shear
surface, and presents the result as the FS. The program then sorts the trial shear surfaces and
identifies the surface with the lowest FS,or the"critical"shear surface.
We assessed slope stability in the upland areas using for static and seismic conditions. We
assessed seismic conditions using pseudostatic methods, and assuming a horizontal acceleration
of 1/2 of the PGA. To perform our analyses, we developed typical cross sections at the locations of
the east and west dead-end towers, as shown on Figures 6 and 7. Soil parameters used in our
analyses are also shown on Figures 6 and 7.
Slope Stability Analysis Results
The results of our slope stability analyses are provided in Table 5 and shown on Figures 8 through
11.
TABLE 5. SLOPE STABILITY ANALYSIS RESULTS- DEAD-END TOWER LOCATIONS
Location Analyzed Condition Calculated FS
Static 2.49
East Dead-End Towers
Seismic(Pseudostatic) 1.48
Static 6.25
West Dead-End Towers
Seismic(Pseudostatic) 2.53
CONCLUSIONS
Based on our explorations and experience, we anticipate new driven pile and drilled shaft
foundations are feasible at the proposed new tower locations. Driven pile and drilled shaft
foundations should extend into the glacially consolidated soils (glacial till unit and advance
outwash unit) to develop sufficient axial capacity and limit settlement. High axial capacities are
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available for driven piles and drilled shafts with relatively shallow embedment into the glacially
consolidated soils. We expect that the minimum embedment depth for both driven piles and
drilled shafts may be controlled by lateral capacity demand rather than axial capacity demand. The
structural engineer should use the axial and lateral capacity recommendations provided in this
report to establish minimum embedments for piles and shafts. Because of the very dense nature
of the glacially consolidated soils, we anticipate hard driving or difficult drilling could be
encountered at relatively shallow penetrations into these soil units.
RECOMMENDATIONS
Upland Dead-End Tower Areas
Site Preparation and General Earthwork
GENERAL
We anticipate that site development work for the upland towers will include stripping and clearing,
site grading, preparing subgrades for access roads and placing and compacting fill and backfill
materials. We expect that the majority of site grading can be accomplished with conventional
earthmovin equipment in ro er working order. Cobbles and boulders could be present in the
i gproper g
glacial till soils and possibly the advance outwash deposits present at the site. The contractor
should be prepared to deal with cobbles and boulders. Some of the soil deposits at the site are
also dense to very dense and may be difficult to excavate. The following sections provide general
recommendations for earthwork,site development and fill materials.
STRIPPING AND CLEARING
Based on our explorations and site observations, we anticipate an initial stripping depth of 6 to
12 inches will be required to remove sod and organic-rich soil, where present. Greater stripping
depths may be required to remove fill and/or localized zones of loose or organic-rich soil, or if
stripping operations cause excessive disturbance to subgrade soil. Stripping should extend at least
5 feet beyond all structural areas. Trees, stumps and roots greater than about 1/2-inch diameter
should be removed as part of the stripping and clearing process.
SUBGRADE PREPARATION
Subgrades for access roads should be thoroughly compacted to a uniformly firm and unyielding
condition after completion of stripping, and before placing structural fill to establish grades. We
recommend that prepared subgrades be proof-rolled where practical to identify areas of yielding
prior to placement of base course material or other structural elements. Proof-rolling should be
accomplished with a heavy piece of construction equipment such as a loaded dump truck or front-
end wheel loader; where proof-rolling is not practical, the exposed subgrade soil should be probed
by an experienced person, using a steel probe rod. If soft or otherwise unsuitable areas are
revealed during proof-rolling or probing that cannot be compacted to a stable and uniformly firm
condition, we recommend that: 1) the subgrade soils be scarified (e.g., with a ripper or farmer's
r n recom acted• or 2 the unsuitable soils be removed and replaced with structural
disc), aerated and p ) p
fill, as needed. An overexcavation depth of 2 to 3 feet is typically adequate for access road
subgrades.
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TEMPORARY EXCAVATION SUPPORT
Excavations deeper than 4 feet should be shored or laid back at a stable slope if workers are
required to enter. Shoring and temporary slope inclinations must conform to the provisions of Title
296 Washington Administrative Code (WAC), Part N, "Excavation, Trenching and Shoring."
Regardless of the soil type encountered in the excavation, shoring, trench boxes or sloped
sidewalls will be required under Washington Industrial Safety and Health Act(WISHA). The contract
documents should specify that the contractor is responsible for selecting excavation and
dewatering methods, monitoring the excavations for safety and providing shoring, as required, to
protect personnel and structures.
In general, based on our observations and explorations, temporary cut slopes in on-site soils
should be inclined no steeper than about 1-1/2H:1V. This guideline assumes that all surface loads
are kept at a minimum distance of at least one-half the slope height away from the top of the slope
and that significant seepage is not present on the slope face. Flatter slopes will be necessary
where significant seepage occurs, where soils are disturbed or if voids are created during
excavation. Sloughing and raveling of temporary cut slopes should be expected. During periods of
wet weather,temporary slopes should be covered with heavy plastic sheeting.
We observed perched groundwater at depths of about 3 to 3.5 feet bgs in the upland areas.
Temporary excavations that extend below this depth may require dewatering and/or temporary
shoring. We recommend that the contract documents specify that the contractor is responsible for
design of dewatering and shoring systems, if required.
PERMANENT CUT AND FILL SLOPES
In general, we recommend that permanent cut and fill slopes be constructed at a maximum
inclination of 2H:1V. Where 2H:1V permanent slopes are not feasible, retaining structures should
be considered. Slopes should be re-vegetated as soon as practical to reduce the surface erosion
and sloughing. Temporary protection should be used until permanent protection is established. In
order to achieve uniform compaction, we recommend that fill slopes be overbuilt and subsequently
cut back to expose well-compacted fill.
Wet Weather Earthwork
Portions of the on-site soil contain a high percentage of fines (material passing the U.S. Standard
No. 200 sieve) and are moisture sensitive. When the moisture content of the soil is more than a
few percent above the optimum moisture content,this soil may become muddy and unstable and it
will be difficult or impossible to meet the required compaction criteria. Disturbance of near-surface
soil should be expected if earthwork is completed during periods of wet weather.
The wet weather season generally begins in October and continues through May in this area;
however, periods of wet weather may occur during any month of the year. The optimum earthwork
period for this type of soil is typically June through September. If wet weather earthwork is
unavoidable,we recommend that:
■ Structural fill placed during the wet season or during periods of wet weather consist of select
granular fill as defined in this report.
Page 10 May 2,2012 GeoEngineers,Inc.
File No.4682-028-02
I
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
■ The ground surface should be sloped to direct surface water away from the work area. The
ground surface should be graded such that areas of ponded water do not develop. Measures
should be taken by the contractor to prevent surface water from collecting in excavations and
trenches. Measures should also be implemented to remove surface water from the work area.
■ Earthwork activities should not take place during periods of heavy precipitation.
■ Slopes with exposed soil should be covered with plastic sheeting or otherwise protected from
erosion.
■ Measures should be taken to prevent on-site soil and soil stockpiles from becoming wet or
unstable. The site soil should not be left uncompacted and exposed to moisture. Sealing the
surficial soil by rolling with a smooth-drum roller prior to periods of precipitation should reduce
the extent that the soil becomes wet or unstable.
■ Construction traffic should be restricted to specific areas of the site, preferably areas that are
surfaced with materials not susceptible to wet weather disturbance.
■ Construction activities should be scheduled so that the length of time that soil is left exposed
to moisture is minimized.
■ A layer of 4-to 6-inch quarry spalls may be needed in high traffic areas of the site to protect the
subgrade soil from disturbance.
■ Contingencies should be included in the project schedule and budget.
Structural Fill Materials
GENERAL
Structural fill must be free of debris, organic material and rock fragments larger than 6 inches. The
workability of material used as structural fill will depend on the gradation and moisture content of
the soil. As the amount of fines increases, soil becomes increasingly sensitive to small changes in
moisture content and adequate compaction may become difficult or impossible to achieve. If
construction is performed during wet weather conditions, we recommend using fill consisting of
well-graded sand and gravel or crushed rock containing less than 5 percent fines by weight based
on the minus 3/4-inch fraction. If prolonged dry weather prevails during the earthwork phase of
construction, a somewhat higher fines content may be acceptable.
SELECT GRANULAR FILL
Select granular fill should consist of well-graded sand and gravel or crushed rock with a maximum
particle size of 3 inches and less than 5 percent fines by weight based on the minus 3/a-inch
fraction. Organic matter, debris or other deleterious material should not be present. In our
opinion, material conforming to Washington State Department of Transportation (WSDOT)
Specification 9-03.9 (Aggregates for Ballast and Crushed Surfacing), 9-03.10 (Aggregate for Gravel
Base), or 9-03.14 (Borrow) is suitable for use as select granular fill, provided that the fines content
is less than 5 percent (based on the minus 3/4-inch fraction) and the maximum particle size is
3 inches.
ON-SITE SOIL
Based on our subsurface explorations, it is our opinion that the inorganic mineral soil present on
site may be considered for use as structural fill, provided it can be placed and compacted as
recommended. Large cobbles (greater than 6 inches in maximum dimension) and boulders, if
I
GEOENGINEERS� May2,2012 Page it
File No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
present, must be removed before using on-site soil for structural fill. Portions of the on-site soils
were observed to have a relatively high fines content, which could make them difficult or
impossible to compact when wet or if earthwork is performed during wet weather.
Structural Fill Placement and Compaction
GENERAL
Structural fill should be compacted at a moisture content near optimum. The optimum moisture
content varies with the soil gradation and should be evaluated during construction. Silty soil and
other fine-grained soil can be difficult or impossible to compact during wet conditions.
Fill and backfill material should be placed in uniform, horizontal lifts and uniformly densified with
vibratory compaction equipment. The maximum lift thickness will vary depending on the material
and compaction equipment used, but generally should not exceed 12 inches in loose thickness.
Fill placement on slopes steeper than 5H:1V must be benched into the slope face. The
configuration of the benches depends on the equipment being used and the slope geometry.
We recommend structural fill be compacted to at least 95 percent of the maximum dry density
(MDD)determined by ASTM Test Method D 1557 (modified Proctor).
Drilled Shafts
INSTALLATION CONSIDERATIONS
Based on our explorations, we anticipate drilling for shaft foundations could encounter cobbles and
boulders, especially in the glacial till deposits. We also anticipate that caving could occur,
particularly within the recessional lake marginal outwash and advance outwash deposits. The
contractor must be prepared to deal with these drilling conditions.
Based on groundwater levels observed in our explorations, we expect that foundation excavations
could encounter perched groundwater at relatively shallow depths. We did not observe
groundwater under artesian pressures in our upland explorations. However, based on the
topography and our understanding of groundwater conditions in the area, groundwater under
artesian pressures could be encountered in the advance outwash deposits. We anticipate heaving
(flowing) soil conditions could also be encountered during drilled shaft excavation, in the poorly
cemented portions of the advance outwash unit. To control heave, the contractor should be
prepared to use casing and drilling fluid for the entire depth of the excavation.
DESIGN CONSIDERATIONS
AXIAL SHAFT CAPACITY
We evaluated axial downward and uplift resistance for 5- and 6-foot-diameter drilled shaft
foundations for the upland tower locations, in general accordance with the 2010 American
Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor
Design (LRFD) Bridge Design Specifications. LRFD uses resistance factors to reduce the total
foundation resistance in order to account for uncertainty in the design model and soil properties.
AASHTO provides recommended resistance factors for different foundations, soil types analysis
methods, and installation methods. AASHTO LRFD soil types include sand, clay and Intermediate
Geo Material (IGM). Figures 12 through 15 present our recommendations for factored shaft
resistance versus elevation for the east dead-end tower area. Figures 16 through 19 present our
Page 12 May2,2012 GeoEngineers,Inc.
Re No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
recommendations for factored shaft resistance versus elevation for the west dead-end tower area.
Applicable resistance factors for each soil type and limit state are shown on the respective figures.
Structural capacity of the shafts should be evaluated by the structural engineer.
SETTLEMENT
Drilled shaft settlement under design loads is not expected to exceed about 1 inch while
differential settlement between comparably loaded drilled shafts is not expected to exceed about
1/2 inch. Proper construction control is necessary to limit soil disturbance at the tip of the shaft.
Excessive soil disturbance, particularly at the tip of the shaft excavation, may result in increased
settlement.
SOIL PARAMETERS FOR DFSAP ANALYSIS
Tables 6 and 7 present our recommended soil parameters for use in DFSAP analysis of lateral
shaft resistance at the east and west dead-end tower locations. We recommend that lateral
resistance analyses for the upland drilled shafts utilize the "Slope of Ground Surface" option within
DFSAP. We recommend using a slope angle consistent with the ground surface slope in the
proposed tower locations.
TABLE 6. DFSAP SOIL PARAMETERS - EAST DEAD-END TOWER AREA
Depth DFSAP Soil Effective Unit Cohesion
Soil Unit Range Type Weight(pcf) (deg) (psf) C50
(feet bgs)
Recessional Lake-Marginal 0-20 sand 60 32 0 0.01
Outwash Deposits
Advance Outwash Deposits 20-70 c-+soil 60 36 200 0.008
TABLE 7. DFSAP SOIL PARAMETERS -WEST DEAD-END TOWER AREA
Depth DFSAP Soil Effective Unit Cohesion
Soil Unit Range Type Weight(pcf) (deg) (psf) Ssp
(feet bgs)
Glacial Till 0-26 c- soil 65 40 500 0.005
Advance Outwash Deposits 26-70 c- soil 60 36 200 0.008
In-Water Tower Area
Driven Piles
INSTALLATION CONSIDERATIONS
Based on our subsurface explorations and experience, we anticipate advancing driven piles into
the glacially consolidated soils could be difficult. Based on our experience with pile installation in
similar soil conditions, we anticipate that open-ended steel pipe piles can likely be easily vibrated
or driven through the marine/alluvial deposits unit and glaciolacustrine silt unit, and possibly
vibrated 10 to 15 feet into the glacial till unit. Greater penetration into glacially consolidated soils
will likely require impact driving and could require internally drilling out the pile during installation
to remove the soil plug. We expect cobbles and boulders could be encountered in the glacially
GEOENGINEERS� May2,2012 Page 13
File No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
consolidated soils during pile installation. Contractors should be prepared to deal with these
conditions.
The contractor should also be prepared for tidal variations, which may limit vessel mobility,
especially during low tides. Depending on the tides and anchorage equipment used, installing piles
from a barge or derrick may be difficult. If a barge or derrick is to be used during pile installation,
we recommend it be equipped with spuds rather than anchors. Alternatively, temporary work
platforms may be considered. During our drilling activities, the barge operator experienced
difficulty holding the barge steady with three anchors during rising and falling tides, due in part to
the very soft/very loose soils present at mudline.
DESIGN CONSIDERATIONS
AXIAL PILE CAPACITY
To achieve required capacity and to limit settlement, piles must extend into the glacially
consolidated soils. Capacity and required embedment depth into the glacially consolidated soils
should be determined by the structural engineer based on the capacity recommendations
provided.
We evaluated axial downward and uplift resistance for 30-inch-diameter driven steel pipe piles for
the in-water tower, in general accordance with the 2010 AASHTO LRFD Bridge Design
Specifications. LRFD uses resistance factors to reduce the total foundation resistance in order to
account for uncertainty in the design model and soil properties. AASHTO provides recommended
resistance factors for different foundations, soil types analysis methods, and installation methods.
AASHTO LRFD soil types include sand, clay and Intermediate Geo Material (IGM). Figures 20 and
21 present our recommendations for factored pile resistance versus elevation for the in-water
tower area. Applicable resistance factors for each soil type and limit state are shown on the
respective figures.
The downward resistances presented herein are based on the assumption that a soil plug will form
inside the pile during impact driving in the glacially consolidated soils. We anticipate that a soil
plug will likely form during impact driving, but is not likely to form during vibratory driving.
Structural capacity of the piles should be evaluated by the structural engineer. For the extreme
limit state,the structural engineer should also apply a downdrag load of 40 kips per pile to account
for negative skin friction resulting from soil liquefaction.
SETTLEMENT
Pile settlement under design loads is not expected to exceed about 1 inch while differential
settlement between comparably loaded piles is not expected to exceed about 1/2 inch. Proper
construction control is necessary to limit soil disturbance if pile drill-out is required. Excessive soil
disturbance at the tip may result in increased settlement. _
SOIL PARAMETERS FOR LPILE ANALYSIS
Our recommendations for soil parameters for use in lateral pile capacity analyses using LPILE are
presented in Table 8. The soil parameters are appropriate for assessing soil-pile interaction under
static loading conditions. To account for liquefied soil conditions during the design seismic events,
we recommend the p-multipliers in Table 9 be applied to the p-y curves generated by the LPILE
analysis. Depending on pile spacing, p-multipliers to account for pile group effects may also be
Page 14 May 2,2012 GeoEngineers,Inc.
Hie No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County.Washington
appropriate. Table 10 summarizes our recommended p-multipliers to account for group effects. In
our opinion, it is not necessary to consider group effects for piles spaced greater than 5 diameters
center-to-center. P-multipliers for piles spaced between 3 and 5 diameters center-to-center may be
linearly interpolated. We do not recommend pile spacing less than 3 diameters center-to-center for
this project.
TABLE S. STATIC LPILE SOIL PARAMETERS
Design Sol[ Static Soil Parameters
Soil Unit Profile Depth Effective Unit LPILE
Range(feet bmi) Weight(pci) Soil Type ¢(deg) K(psi) C(psi) Eao
Marine/Alluvial 0-28 0.023 Sand 28 20 N/A N/A
Deposits (Reese)
Glaciolacustrine 28-33 0.029 Soft Clay N/A N/A 8.33 0.015
Silt (Matlock)
Glacial Till 33-63 0.038 Silt 40 250 3.47 0.005
Advance Below 63 0.035 Silt 36 225 1.39 0.008
Outwash
TABLE 9. P-MULTIPLIERS FOR SEISMIC LPILE ANALYSIS
Depth Range(feet below mudline) P-multiplier
0-15 0.05
15-20 0.15
20-30 0.05
Below 30 1.0
TABLE 10. P-MULTIPLIERS FOR GROUP ACTION
Center-to-Center Spacing Leading Row Trailing Row
3 diameters 0.6 0.4
5 diameters 1.0 0.85
Pile Anchors
If additional uplift capacity is required for driven steel pipe piles, pile anchors (also known as
micropiles) may be considered. Pile anchors are typically used to increase uplift capacity of open-
ended piles that have been driven through weak soils to refusal on dense soils or rock. If a pile is
to be anchored,the soil within the pile is cleaned out and a drilling pipe with centralizers is lowered
to the pile tip. The anchor hole is then drilled to the required depth and drill cuttings are removed.
The anchor, generally either a steel bar or stranded cable is fed down the drilling pipe, along with a
grout injection tube. Grout is injected through the tube and allowed to cure. Anchors may be
stressed and connected to the pile cap, or left unstressed and connected to the pile with an
appropriate connection. Pile anchor diameters are commonly in the 6-to 8-inch range.
CiEOENGINEERS� May2,2012 Page 15
File No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
Based on the site soil conditions and our experience, we anticipate pile anchors with a 6-to 8-inch-
diameter would have an ultimate uplift(pull out) capacity of 5 kips or more per lineal foot(klf), over
the bonded length. We anticipate cobbles and possibly boulders may be encountered in the
glacially consolidated soils. Piles and pile anchors extending into the advance outwash may
encounter artesian conditions. We recommend the contractor be prepared to deal with difficult
pile and anchor installation conditions.
The capacity of pile anchors is performance based and highly dependent upon the contractor's
installation procedures and methods. Typically, the structural engineer will provide the contractor
with the loading, connection details and corrosion protection requirements. The contractor then
determines the size of the anchor and the installation depth. Final anchor capacities are typically
determined from field load tests.
LIMITATIONS
We have prepared this report for exclusive use by Tacoma Public Utilities, Electric Power Systems,
Inc. BergerABAM and DEA for Phase II design of the North Bay Crossing portion of the Potlatch
Transmission Lines project located in Mason County, Washington.
Within the limitations of scope, schedule and budget, our services have been executed in
accordance with generally accepted practices in the field of geotechnical engineering in this area
at the time this report was prepared. No warranty or other conditions, express or implied, should
be understood.
Please refer to Appendix B titled "Report Limitations and Guidelines for Use" for additional
information pertaining to use of this report.
REFERENCES
2002 Interactive Deaggregations, United States Geological Survey-Earthquake Hazards Program,
(http://egint.cr.usgs.gov/deaggint/2002/index.php). Accessed February 2, 2012.
American Society of Civil Engineers. "Substation Structure Design Guide."ASCE Manuals and
Reports on Engineering Practice No. 113. 2008.
California State Lands Commission. 2010. "Marine Oil Terminal Engineering and Maintenance
Standards" (MOTEMS).
Electric Power Systems, Inc. "Basis of Design Memorandum, Potlatch Transmission Line, North
Bay and Henderson Bay Crossings." 2009.
Electric Power Systems, Inc. "Basis of Design Memorandum, Potlatch Transmission Line, North
Bay Crossings." 2012.
GEO-SLOPE International, Ltd. (2007). "Slope/W"Version 7.14."
Page 16 May2,2012 GeoEngineers,Inc.
Hie No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
Idriss, I.M. and Boulanger, R.W. 2004. "Invited Paper,Semi-Empirical Procedures for Evaluating
Liquefaction Potential During Earthquakes," Proceedings of the 110 ICSDEE&3rd ICEGE,
pp 32-56.
Idriss, I.M. and Boulanger, R.W. 2008.Soil Liquefaction During Earthquakes, Monograph Series,
No. MNE-12, Earthquake Engineering Research Institute.
International Code Council, 2009. "2009 International Building Code."
Polenz, Michael;Alldritt, Katelin; Hehemann, N.J ;Sarikhan, I.Y.; Logan, R.L. 2009. Geologic Map
of the Belfair 7.5-minute Quadrangle, Mason, Kitsap, and Pierce Counties,Washington:
Washington Division of Geology and Earth Resources Open File Report 2009-7, 1 sheet,
scale 1:24,000.
Seed, H.B.,and Idriss, I.M., 1971. Simplified Procedure for Evaluating Soil Liquefaction Potential,
J. Soil Mechanics and Foundations Div.,ASCE 97(SM9), 1249-273).
Seed, R.B.,Cetin, K.O., Moss, R.E.S., Kammerer,A.M.,Wu,J., Pestana,J.M., Riemer, M.F., Sancio,
R.B., Bray,J.D., Kayen, R.E.and Faris,A. 2003. "Recent Advances in Soil Liquefaction
Engineering:A Unified and Consistent Framework," Earthquake Engineering Research
Center, Report No. EERC 2003-06, College of Engineering, University of California,
Berkeley.
Youd,T.L. and Idriss, I.M. "Liquefaction Resistance of Soils: Summary Report from the 1996
NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of
Soils",Journal of Geotechnical and Geo-environ mental Engineering,ASCE,Vol. 127, No.
10, pp. 297-313. 2001.
GEOENGINEERS/ May 2,2012 Page 17
File No.4682-028-02
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GeoEngineers, Inc. cannot guarantee the accuracy and content
of electronic files. The master file is stored by GeoEngineers,
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L Reference: ESRI Data&Maps:Street Maps USA(2005)and
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Notes: A A Feet Mason County, Washington
1.The locations of all features shown are approximate. �--� Cross Section
e2.This drawing is for infomation purposes. It is intended to assist in showing features discussed S
in an attached document. GeoEngineers,Inc.cannot guarantee the accuracy and content of �� Proposed Tower Location G EO E N G I N E E R S Figure 2
electronic files. The master file is stored by GeoEngineers,Inc. and will serve as the official record
of this communication.
a
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140 140
120 120
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Potlatch Transmission Lines - North Bay Crossing
`s Notes:
¢ Mason County Washington
ci 1. The subsurface conditions shown are based on interpolation between widely spaced explorations and should be considered approximate;actual subsurface conditions may vary from those shown.
2. Refer to Figure 2 for location of Cross Section.
3. This figure is for informational purposes only.It is intended to assist in the identification of features discussed in a related document.Data were compiled from sources as listed in this figure.The G EO E N G I N E E RS Figure re 3
data sources do not guarantee these data are accurate or complete.There may have been updates to the data since the publication of this figure.This figure is a copy of a master document.The
master hard copy is stored by GeoEngineers,Inc.and will serve as the official document of record.
a
Potlatch - North Bay Crossing
Map-Based Response Spectra
1
Site Class C Site Class D Site Class E
0.9 ———— \
4.......... \ IBC(2/3*2475) •••••• IBC(2/3*2475) ——— IBC(2/3*2475)
0.8 TA MOTEMS(475) MOTEMS(475) ——— MOTEMS(475)
11 ♦ %
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Period (seconds)
Map-Based Response Spectra
o Potlatch Transmission Lines - North Bay Crossing
N Mason County, Washington
0
CO
GEoENGINEERS Figure 4
Potlatch - North Bay Crossing
Recommended Response Spectra
1
Site Class C Site Class D Site Class E
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0.8 - - — MOTEMS(475) MOTEMS(475) --- MOTEMS(475)
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Period(seconds) Recommended Response Spectra
Potlatch Transmission Lines- North Bay Crossing
o Mason County, Washington
co
GEoENGINEERS r Figure 5
4682-028-02
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Potlatch Transmission Lines — North Bay Crossing
Mason County, Washington
GEOENGINEER Figure 6
4682-028-02
1m
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Mason County, Washington
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4682-028-02
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Potlatch Transmission Lines — North Bay Crossing
Mason County, Washington
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4682-028-02
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Potlatch Transmission Lines — North Bay Crossing
Mason County, Washington
GEOENGINEER� Figure 9
4682-028-02
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W 00 Unit Wei4h1 120 pcf ` -- ______________
so Cohesion 200 psl
f Phi,36"
ao�-
10
10
0
D;�tnre ift`
SLOPE/W Analysis —West— Static
Potlatch Transmission Lines — North Bay Crossing
Mason County, Washington
GEOENG(NEER Figure 10
4682-028-02
2.53
,m
t30 tw Bonng B-5
VA Name.Glacial
„o OE nit Weight: ,. .
§11- 00 psf
SR 3
ame Advance Outwash -------------
W ,ro Unit Weight:120 pcf - '--
� Cohesion.200 psl I
Phi 36'
40
b
20
,o - -- —
__ _ „K w wo so a aoo eo - -2w -200 -150 -100 -s0 0 50 2on
Distance(ft)
SLOPE/W Analysis — West— Seismic
Potlatch Transmission Lines — North Bay Crossing
Mason County, Washington
GEOENGINEERS Figure 11
Subsurface Extreme Limit State
Profile Axial Resistance (kips)
0 1,000 2,000 3,000 4,000 5,000
80 --- — 80 kv
Recessional — — Unfactored End Bearing
Lake-Marginal - - - Unfactored Skin Friction
Outwash
70 70 r•Extreme Skin Friction
Extreme End Bearing
Total Extreme Axial Capacity
60 60 A
Advance
Outwash t
1
50 50 —; --- —
N �
0 40 0 40 —!� — --- --' '--,
w W j
30 30 -- --- —
t
20 20 ---
4-d
10 10
0 0 1
i
1. The pile capacities were developed in general ac
Geotechnical Design Manual (GDM). North Bay Crossing - East Towers
2. The plots are based on a single shaft and do not
Potlatch Transmission Lines -
3. The service case assumes 1 inch of shaft settlerr North Bay Crossing
0 4. The appropriate LRFD resistance factors, as pre: Mason County, Washington
CO
EoENGINEERs Figure 12
LRFD Drilled Shaft Uplift Capacity
5-foot Diameter Drilled Shaft
Subsurface Uplift Capacity
Profile
Axial Resistance (kips)
0 500 1,000 1,500 2,000 2,500 3,000
80 80
Recessional
Lake-Marginal Extreme
Outwash
Strength
70 70 --- ---
-Service
44 - - - Unfactored
60 60 -- ——— -- ----
Advance
Outwashtl
t
50 50 ---
4r W i
.040 p 40 — — — -- ---
> f°
a�
w w
30 30 -- ---
20 20 ---
10 io
I
0 0
General Notes
1. See Figure 12 for general notes. North Bay Crossing - East Towers
Resistance Factors Potlatch Transmission Lines -
Uplift North Bay Crossing
o Sand 0.45 Mason County, Washington
N
o Clay 0.35
CO IGM 0.45
GEOENGINEERS Figure 13
v
LRFD Drilled Shaft Downward Capacity
6-foot Diameter Drilled Shaft
Subsurface Service Limit State Strength Limit State Extreme Limit State
Profile Axial Resistance (kips) Axial Resistance (kips) Axial Resistance (kips)
0 500 1,000 1,500 2,000 2,500 3,000 0 500 1,000 1,500 2,000 2,500 3,000 0 1,000 2,000 3,000 4,000 5,000
80 80 W j., 80 80
Recessional Unfactored End Bearing
r •Skin Friction -Skin Friction I r -— g
Lake-Marginal End Bearing I End Bearing - Unfactored Skin Friction
OUtWaSh
70 70 — — Total Service Capacity 70 -- Total Strength Capacity 70 — — Extreme Skin Friction
Extreme End Bearing
LI
Total Extreme Axial Capacity
60 60 I —
--- ——— ——— — --- 60 j - -- ----- -- 60Mon
—
Advance 1
Outwash -
50 -
50 — — --- — 50 -�— -- -- 50 -- -
OJ
t
-� CU
.2 40 o 40 — -- — -- p 40 - p 4041
- ---
ra41 41
—
> _ - - -a>i au > >
' v � v
w 44-
w - — - —
30 14+ w -- w i
30 , — --- -- 30 -- --� -- --- — — 30 --- -- --
I
_ --
10 10 FTTT. 10 — --- 10 —
i _
0
' General Notes
1. The pile capacities were developed in general accordance with the 2010 AASHTO LRFD Bridge Design Manual and the 2008 WSDOT F i esstance actors North Bay Crossing - East Towers
Geotechnical Design Manual (GDM). R y g
' 2. The plots are based on a single shaft and do not consider group effects of closely spaced shafts. Skin End Potlatch Transmission Lines-
North Bay Crossing
N
3. The service case assumes 1 inch of shaft settlement. Sand 0.55 0.5 Mason County, Washington
' 9 4. The appropriate LRFD resistance factors, as presented in the"Resistance Factors"table are included in the plots presented above. Clay 0.45 0.4
00
IGM 0.6 0.55 GEoENGINEERS� Figure 14
cfl
I �
1
LRFD Drilled Shaft Uplift Capacity
6-foot Diameter Drilled Shaft
Subsurface Uplift Capacity
Profile
Axial Resistance (kips)
0 500 1,000 1,500 2,000 2,500 3,000
80 Recessional 80
Lake-Marginal -Extreme
Outwash
70 Strength
70 •Service
— — — Unfactored
60 60 — — t I
Ni
Advance
Outwash TM
50
50
'7
t
p 40 p 40 T_
R 1 a> > -
a�
W UJ
30 30 -- --
20 20
10 10 — —
0 0 I _i
General Notes
1. See Figure 14 for general notes. North Bay Crossing - East Towers
Resistance Factors Potlatch Transmission Lines-
Uplift North Bay Crossing
q Sand 0.45 Mason County, Washington
N
o Clay 0.35
00,, IGM 0.45
GEOENGINEERS� Figure 15
Subsurface Extreme Limit State
Profile Axial Resistance (kips)
0 1,000 2,000 3,000 4,000 5,000
95 95
Glacial Till — — Unfactored End Bearing
— — — Unfactored Skin Friction
85 85 __ •Extreme Skin Friction
Extreme End Bearing
Total Extreme Axial Capacity
75 75 J— — ———
65 Advance 65
Outwash —
a� +'
0 55 p 55 -- -- ---
M *,
>
a>
w w
45 45 —
35 35 --
25 25
15 15
1. The pile capacities were developed in general ac
Geotechnical Design Manual (GDM). North Bay Crossing - West Towers
2. The plots are based on a single shaft and do not
Potlatch Transmission Lines -
3. The service case assumes 1 inch of shaft settlen North Bay Crossing
0 4. The appropriate LRFD resistance factors, as pre: Mason County, Washington
00
N
N EoENGINEERS Figure 16
LRFD Drilled Shaft Uplift Capacity
5-foot Diameter Drilled Shaft
Subsurface Uplift Capacity
Profile
Axial Resistance (kips)
0 500 1,000 1,500 2,000 2,500 3,000
95 95
Glacial Till
Extreme
Strength
85 85 --- --
Service
- - - Unfactored
75
75 -- -
65 Advance 65 —
Outwash - I
i
0 55 0 55 - — --- --- ——— —._.._...
> >
LLU Uj
45 45 --- --- _��
35 35 — — - ----
i
25 25 —
1_
15 15 ---
General Notes
1. See Figure 16 for general notes. North Bay Crossing - West Towet
Resistance Factors Potlatch Transmission Lines-
Uplift North Bay Crossing
04
o Sand o.45 Mason County, Washington
co
N
o Clay 0.35
CO(.0 IGM 0.45 GEOENGINEERS� Figure 17
Subsurface Extreme limit State
Profile Axial Resistance (kips)
0 ,000 2,000 3,000 4,000 5,000
95 95
Glacial Till — — Unfactored End
i Bearing
- - - Unfactored Skin
85 85 -- Friction
•Extreme Skin Friction
75 75 Extreme End Bearing
33 Total Extreme Axial
-t Capacity
65 Advance 65 --i -- --- --
Outwash =i
au
i
0 55 0 55 -- --
41 +,
M M
>a� >
au -
- 3 r
W W
f
45 45 -- — --
35 35 — ---
25 25 —
�t
15 J 15
1. The pile capacities were developed in general aG North Bay Crossing - West Towers
Geotechnical Design Manual (GDM).
2. The plots are based on a single shaft and do not potlatch Transmission Lines -
3. The service case assumes 1 inch of shaft settlerr North Bay Crossing
0 4. The appropriate LRFD resistance factors, as pre: Mason County, Washington
CO
N EOENGINEERS� Figure 18
00
CD
LRFD Drilled Shaft Uplift Capacity
6-foot Diameter Drilled Shaft
Subsurface Uplift Capacity
Profile
Axial Resistance (kips)
0 500 1,000 1,500 2,000 2,500 3,000
95 -- 95
Glacial Till
Extreme
Strength
85 85 -- ---
Service
- Unfactored
75 75 --- ----�
65 Advance 65 FIT
Outwash
Gvl '
t �
0 55 p 55 —
> vv
W w
45 45 --
_ _
I
35 35 --- ----
25 25 —
I
15 - 15
General Notes
1. See Figure 18 for general notes. North Bay Crossing - West Towers
Resistance Factors Potlatch Transmission Lines -
Uplift North Bay Crossing
CO
Sand 0.45 Mason County, Washington
(V
o Clay 0.35
CO
IGM 0.45 GEQENGINEERS� Figure 19
LRFD Driven Pile Downward Capacity
30-Inch Diameter Steel Pipe Pile
Subsurface Service Limit State Strength Limit State 01 Extreme Limit State
Profile Axial Resistance (kips) Axial Resistance (kips) Axial Resistance (kips)
0 500 1,000 1,500 0 500 1,000 1,500 0 500 1,000 1,500 2,000
0 Marine Deposits 0 A 0 0
•Skin Friction -Skin Friction - — — Unfactored End Bearing
End Bearing End Bearing - - - Unfactored Skin Friction
Total Service Capacity Total Strength Capacity -Extreme Skin Friction
-10 -10 --- — -10 -- ---- -10 --- Extreme End Bearing
Total Extreme Axial Capacity
-414-20 -20 — -20 -- -zo ---
--
p -30 Glaciolacustrine C _30 — --'— p -30 v--- --- p -30 ---- — — —
> > > > t
d v v
w Glacial Till iu j w
-40 -40 ` — 40 -40 — --
-50 -50 - - -50 , 50 --- --
i
-60 -60 FTI -60 -60
Lowest Elevation of Liquefaction
General Notes
1. The pile capacities were developed in general accordance with the 2010 AASHTO LRFD Bridge Design Manual and the 2008 WSDOT
Strength Resistance Factors North Bay Crossing - In-Water Foundation
Geotechnical Design Manual (GDM). y g
2. The plots are based on a single pile and do not consider group effects of closely spaced piles. Skin End Potlatch Transmission Lines-
N 3. The service case assumes 1 inch of pile settlement. Sand 0.45 0.45 North Bay Crossing
9 4. The appropriate LRFD resistance factors, as resented in the"Resistance Factors"table are included in the lots resented above. Mason Count Washington
0o P P P Clay 0.35 0.35 y, gt
o5. Effects of liquefaction are included in the Extreme Case.
w6. Resistances are not reduced to account for liquefaction-related downdrag loads in the Extreme Case. G EO E N G I N E E R Figure 20
cD
Nr
LRFD Driven Pile Uplift Capacity
Sainch Diameter Steel Pipe Pile
Subsurface
Uplift Capacity
Profile
Axial Resistance (kips)
0 100 200 300 400 Soo
0 0 -
Marine Deposits
Extreme
Strength
-10 -10 -- - Unfactored
t
t
-20 -20 t
It
t "
� t
a� v ►_
v
p 30 Glaciolacustrine p -30 �— —
.2
> I J
v >
a� -
w Glacial Till w
-40 -40 ,
,
-50 -50
i
"
-60 -60
— Lowest Elevation of Liquefaction
General Notes
1. See Figure 20 for general notes. North Bay Crossing- In-Water Foundation
Resistance Factors Potlatch Transmission Lines-
Strength Extreme North Bay Crossing
N Mason County, Washington
o Sand 0.35 0.80
00
Clay 0.25 0.801G M E N G I N E E R Figure 21
co
v
.- �,-- - — • • ,� APPENDIX A
'`' ` ' ` • Subsurface Explorations and Laboratory Testing
I
1
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
APPENDIX A
SUBSURFACE EXPLORATIONS AND LABORATORY TESTING
General
We explored subsurface conditions at the site by advancing four over-water soil borings completed
between August 17 and 21, 2009 and two on-land soil borings completed on December 29 and
30, 2011. Our representatives located the explorations using hand-held global positioning system
(GPS) equipment. A key to the symbols used on the boring logs is included as Figure A-1.
Summary boring logs are included as Figures A-2 through A-7. GPS coordinates of our boring
locations (referenced to NGVD29) are presented on the boring logs. We are available to provide
updated boring logs using a different coordinate system/datum upon request.
Soil Borings
Over-water drilling was performed by Holocene Drilling using a truck-mounted drill rig under
subcontract to GeoEngineers, from a barge under subcontract to Holocene Drilling. A combination
of hollow-stem auger and mud rotary drilling methods were used to advance the over-water
borings. On-land borings were also performed by Holocene Drilling, using track-mounted drilling
equipment and hollow-stem auger and mud rotary drilling methods. Boring B-1 was advanced to a
depth of about 54 feet below mudline (bml), at which time barge anchorage problems forced us to
abandon the boring. In order to obtain subsurface information below this level, boring B-1b was
advanced near B-1, to a depth of about 76.5 feet bml. Borings B-2 and B-3 were advanced to
depths of about 95 and 53 feet bml, respectively. Borings B-4 and B-5 were both advanced to
depths of about 71.5 feet below ground surface. The borings were backfilled by Holocene Drilling.
Disturbed soil samples were obtained from the borings using a 1.5-inch-inside-diameter split-spoon
standard penetration test(SPT)sampler driven into the soil using a 140-pound hammer free-falling
a distance of 30 inches. The number of blows required to drive the sampler the last 12 inches or
other indicated distance is recorded on the log as the blow count. Additional samples were
periodically obtained using a 2.4-inch-inside-diameter split-barrel sampler, both with and without
rings.
Our representatives continuously monitored the borings, maintained logs of the subsurface
conditions and observed 'sample attempts. The soils encountered were visually classified in
accordance with the system described in Figure A-1, and in general accordance with ASTM
International (ASTM) D 2488.
Laboratory Testing
General
Soil samples obtained from the explorations were transported to GeoEngineers' laboratory.
Representative soil samples were selected for laboratory tests to evaluate the pertinent
geotechnical engineering characteristics of the site soils and to confirm or modify our field
classification. The following paragraphs provide a description of the tests performed.
GEoENGINEERS� May 2,2012 Page A-1
File No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
Moisture Content and Dry Density
The moisture content and density of selected samples were determined in general accordance with
ASTM Test Method D 2937. Test results are used to aid in soil classification and correlation with
other pertinent engineering soil properties. Test results are presented on the boring logs (Figures
A-2 through A-7).
Percent Passing U.S.No.200 Sieve(%F)
Selected samples were "washed" through the U.S. No. 200 mesh sieve to estimate the relative
percentages of coarse-and fine-grained particles in the soil. The percent passing value represents
the percentage by weight of the sample finer than the U.S. No. 200 sieve (fines). This test was
conducted to check field descriptions and to estimate the fines content for analysis purposes. The
tests were conducted in general accordance with ASTM D 1140, and the results are shown on the
boring logs(Figures A-2 through A-7).
Grain-Size Analysis
Grain-size analyses were performed on selected samples in general accordance with ASTM Test
Method D 422. This test provides a quantitative determination of the distribution of particle sizes
in soils. Figure A-8 presents the results of the grain-size analyses.
Page A-2 May 2,2012 GeoEngineers,Inc.
File No.4682-28-02
SOIL CLASSIFICATION CHART ADDITIONAL MATERIAL SYMBOLS
MAJOR DIVISIONS SYMBOLS TYPICAL SYMBOLS TYPICAL
GRAPH LETTER DESCRIPTIONS GRAPH LETTER DESCRIPTIONS
Qo c WELL-GRADED GRAVELS,GRAVEL-
CLEAN O GW SAND MIXTURES Cement Concrete CCGRAVEL GRAVELS /\/\ \
AND
GRAVELLY (LITTLE OR NO FINES) O O O O POORLY-GRADED GRAVELS,
SOILS O O GP GRAVEL-SAND MIXTURES
AC Asphalt Concrete
COARSE GRAVELS WITH GM SILTY GRAVELS,GRAVEL-SAND-
MORE THAN 50% SILT MIXTURES
GRAINED OF COARSE FINES CR Crushed Rock/
SOILS FRACTION Quarry Spalls
RETAINED ON NO. (APPRECIABLE AMOUNT CLAYEY 4 SIEVE OF FINES) GC CLAY MIXTURES$,GRAVEL-SAND-
° TS Topsoil/
Forest Duff/Sod
SW WELL-GRADED SANDS,GRAVELLY
CLEAN SANDS SANDS
MORE THAN 50% SAND
RETAINED ON NO. AND (LITRE OR NO FINES)
200 SIEVE SANDY SIP POORLY-GRADED SANDS,
SOILS GRAVELLY SAND Measured groundwater level in
exploration,well,or piezometer
MORE THAN 50% SANDS WITH SM SILTY SANDS,SAND-SILT
OFCCTION FINES MIXTURES Groundwater observed at time of
FRACTION
PASSING NO — exploration
SIEVE (APPRECIABLE AMOUNT SIC CLAYEY SANDS,SAND-CLAY
OF FINES) JN MIXTURES Perched water observed at time of
INORGANIC SILTS,ROCK FLOUR, exploration
ML LAY SWITH SLIGHT
PLASTICITY Measured free product in well or
INORGANIC Curs OF LOW TO — piezometer
SILTS MEDIUM PLASTICITY,GRAVELLY
LIQUID LIMIT CL
FINE AND LESS THAN 50 CLAYS,SANDY CLAYS,SILTY CLAYS, Graphic Log Contact
GRAINED CLAYS LEAN curs
SOILS ORGANIC SILTS AND ORGANIC Distinct contact between soil strata or
OIL SILTY CLAYS OF LOW PLASTICITY geologic units
INORGANICSILTS,MICACEOUS OR Approximate location of soil strata
MORE THAN 50% MH DIATOMACEOUS SILTY SOILS change within a geologic soil unit
PASSING E 200 I I g g g
SIEVE
SILTS
AND GREATE LIQUID
LIMIT
S.
/ CH INOR C ICCLAYS OFHIGH Material Description Contact
R THANCLAYS ITY
Distinct contact between soil strata or
OH ORGANIC CLAYS AND SILTS OF geologic units
MEDIUM TO HIGH PLASTICITY
Approximate location of soil strata
PEAT,HUMUS,SWAMP SOILS WITH change within a geologic soil unit
HIGHLY ORGANIC SOILS — _ PT HIGH ORGANIC CONTENTS
NOTE Multiple symbols are used to indicate borderline or dual soil classifications
Laboratory/ Field Tests
Sampler Symbol Descriptions %F Percent fines
AL Atterberg limits
® 2.4-inch I.D.split barrel CA Chemical analysis
CP Laboratory compaction test
Standard Penetration Test(SPT) CS Consolidation test
DS Direct shear
■ Shelby tube HA Hydrometer analysis
MC Moisture content
® Piston MD Moisture content and dry density
OC Organic content
PM Permeability or hydraulic conductivity
Push Probe PP Pocket penetrometer
® Bulk or grab SA Sieve analysis
TX Triaxial compression
UC Unconfined compression
VS Vane shear
Blowcount is recorded for driven samplers as the number
of blows required to advance sampler 12 inches(or Sheen Classification
distance noted). See exploration log for hammer weight
and drop. NS No Visible Sheen
SS Slight Sheen
A"P"indicates sampler pushed using the weight of the MS Moderate Sheen
drill rig. HS Heavy NT Not Tested
en
NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions.
Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made;they are not warranted to be
representative of subsurface conditions at other locations or times
KEY TO EXPLORATION LOGS
GMENGINEERS� FIGUREA-1
Start End Total Logged By MM Drilling
Drilled 8/19/2009 859/2009 Depth(ft) Checked By Driller Holocene Drilling Method9Hollow Stem Auger
Surface Elevation(ft) Undetermined Hammer 140-Ib/30-in Autohammer Drilling Truck Mounted Mobile B-59
Vertical Datum Data Equipment
Easting(X) -122.820911 System Groundwater
Northing47.390324 Datum WGS84 Depth to
�) Date Measured Water ft Elevation(ft)
Notes:
FIELD DATA
m
E
MATERIAL
w _ o a z J
O 7Z6DESCRIPTION .N REMARKS
N y N 01 —J U ,�
16
t > N ll
> a y U 3 m E N " l` O m O O
W o � m 0 ins � (7 00 gc) og
ML Brown sandy silt with shell fragments and
organics(very soft,wet)(marine/alluvial
deposits)
5-1 18 7 1 _ _
SM B rown silty fine to coarse sand with trace shell
F fragments(loose,wet)(marine/alluvial 20 %F=14
,76
deposits)
10 0 4
t 5 NIL Gray silt with trace sand(medium stiff,wet)
(glaciolacustrine silt)
18 4 3 44 %F=93
%F
0
0 20 18 14 4
a
N 5 Grades to stiff 24 95
i MD
w
0
i7
w
c? P5 6
y 15 48
w SP-SM Light brown fine to coarse sand with gravel and
Z silt(dense,wet)(glacial till)
z
w
0
zi
2 30 Driller indicates 15 feet of heave in auger,
flush out
E
m
0
'a
Heave,flush out
35
Note:See Figure A-1 for explanation of symbols.
s
s
a
5
Log of Boring B-1
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
E GMENGINEER$ j yFigureA-2
A Project Number: 4682-028-01 Sheet 1 of 2
FIELD DATA
m
w v `s MATERIAL
w y Z J DESCRIPTION r REMARKS
_ °
O d m N J U
r 0
m
m o
W 0 C co fnH � U' (7U 7U cla
35 12 56
Grades to very dense
Drill to 43 feet to try to get out of heave
zone
SM Gray silty fine to coarse sand with gravel(very Driller indicates harder drilling at 38 feet
dense,wet)(glacial till)
40
Driller indicates very hard drilling at 42 fee
6 61-10" 8
45
SP-SM Brown fine to medium sand with trace gravel
(very dense,wet)(glacial till)
10 50-4" 9
50 MI, Light brown sandy silt with gravel(hard,moist) Driller indicates easier drilling at 50 feet
(glacial till)
6 62-6" 10
0
c
0
N
I
S
U
i W
F
O
tW7
I
W
O
O
N
K
2
O
Z
O
W
O
E
EE
ti
'a
c�
z
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-1 (continued)
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
GMENGINEER FigureA-2
Project Number: 4682-028-01 Sheet 2 of 2
Start End Total hogged By MM Drilling
Drilled 8/21/2009 8/21/2009 Depth(ft) 76.5 Dill Holocene Dr
Checked By Driller Drilling Method Hollow Stem Auger
Surface Elevation(ft) Undetermined Hammer 140-Ib/30-in Autohammer Drilling Truck Mounted Mobile B-59
Vertical Datum Data Equipment
Easting(X) -122.820986 System Groundwater
Northing(Y) 47.390306 Datum WGS84 Depth to
Date Measured Water ft Elevation(ft)
Notes: Drill to 50 feet,then sample
FIELD DATA
06
E E m MATERIAL
a w o � � J e REMARKS
5.
> 0 0 _ _ _ DESCRIPTION m
Y m ii C L ❑-
W t7 c tr m V � a)
Is 50 5' SP-SM Brown fine to coarse sand with silt and Dn11 to 50 feet,ffien same e
occasional gravel(very dense,wet)(glacial
till)
Driller indicates easier drilling at—52 feet
GM Brown silty fine to coarse gravel with sand(very
55 12 Sa,,, dense,wet)(glacial till)
so SM Brown silty fine to coarse sand with gravel(very
dense,wet)(glacial till)
DO 10 50-4" 3
65 SP-SM Brown fine to medium sand with silt(very dense
wet)(advance outwash)
❑
18 50-5'• 4
0 70 Driller indicates 1 foot of heave in auger
z
a
w
i
x
V
W
O
w
�I
W
L1
H
�? 75
18 50-5" 5
a
w
z
6
z
w
O
E
r
E
m
❑
a
z
Lt
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-1 b
Project: Potlatch Transmission Lines North Bay Crossing
❑ Project Location: Mason County, Washington
E GWENGINEERS FigureA-3
Project Number: 4682-028-01 Sheet 1 of 1
Start End Total Logged By MM Drilling
Drilled 8/20/2009 8/20/2009 Depth(ft) 95 Checked By Driller Holocene Drilling Method Hollow Stem Auger
Surface Elevation(ft) Undetermined Hammer 140-Ib/30-in Autohammer Drilling Truck Mounted Mobile B-59
Vertical Datum Data Equipment
Easting(X) -122.816967 System Groundwater
Northing(Y) 47.39009 Datum WGS84 Depth to
Date Measured Water ft Elevation(ft)
Notes:
FIELD DATA
a,
a.
MATERIAL
z m J .0o r REMARKS
m DESCRIPTION
ca r o v u c L aN ?m o
> a aa, U 3 m E.N " u1 H e
o � � o o 2 o o z�C
w o 0_ m 0 rn F � U (9 U �() o n
° SM Brown silty fine to medium sand with shell
fragments and organics(very loose,wet)
(marine/alluvial deposits)
5 18 0 1
2 35 %F=33
%F 26 88
3
MD
SM Gray silty fine tomedium sand with shell
fragments(very loose,wet)(marine/alluvial
deposits)
10 2 1 4
ML Brown silt with sand and shell fragments(stiff,
wet)(marine/alluvial deposits)
15 18 5
° SP-Stet Gray fine to coarse sand with silt(loose,wet)—— 16 /F=9
(marine/alluvial deposits)
0
�d 20
0
N
S
Grades to include gravel,shell fragments and
18 4 8 occasional lenses of sandy silt
9
10 hit Gray sandy silt(medium stiff,wet) —————
o (glaciolacustrine silt)
�? 2s
w
i
a
a 12 34 11
12 Slit Brown silty fine to coarse sand with gravel
E (dense,wet)(glacial till)
30
E
F=
07 DO
O
4 504" 13
z 35
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-2
Project: Potlatch Transmission Lines North Bay Crossing
iEd Project Location: Mason County, Washington
C7EOENGINEERS� FigureA-4
Project Number: 4682-028-01 Sheet 1 of 3
FIELD DATA
m
w - _ A s MATERIAL
o w ❑ a z J f0 0 � REMARKS
0 9 _ DESCRIPTION
> L Z O 3 m C N n. 7 y �v=i d p
O N O N O O N N f0 N O 2 •o O Z` i
W ❑ C tY m C,1 In H 0 00
U O a
35 0 GP-GM Brown-gray fine to coarse gravel with sand and Heavy dnll chatter
❑ silt(very dense,wet)(glacial till)
0
6 98-10" 14
0
0
0
0
40 O
0
0
3 50-3" 15 0
0
0
0
45 SP--SM Gray fine to coarse sand with gravel and silt
(very dense,wet)(glacial till)
4 50-4" 16
50
ML Gray silt with trace sand(hard,moist)(glacial
till)
55 17 75-11" 17
SM Gray silty fine to medium sand with trace wood
debris(very dense,wet)(advance outwash) Driller notes easier drilling at 58 feet
60 18 62 18
❑
c
a
z
U
W
O
W
ml 65 19
W 11 50-5"
O
H
O
y
K
W
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Z
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7l)
E
2
18 67 20 ;.
e 21 ML Gray silt with sand(hard,moist)(advance
0
outwash)
0
c?
75 SP sh)
-SM Gray fine to medium sand with silt(very dense,
F wet)(advance outwa
z
Note:See Figure A-1 for explanation of symbols.
s
s
.c
Log of Boring B-2 (continued)
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
GEOENGINEERS FigureA-4
Project Number: 4682-028-01 Sheet 2 of 3
FIELD DATA
n
W E m `s MATERIAL
0 m DESCRIPTION .N REMARKS
io 'o
• r Q 7 a m
N
W 0C LY co Cn
18 69 22
23 M[, Gray silt with sand(hard,moist)(advance
80 outwash)
18 78 24 Grades to light gray sandy silt with occasional
gravel and green and brown mottling
85
SP-SM Gray fine to medium sand with silt(very dense,
wet)(advance outwash)
18 88-9" 25
Driller notes 15 feet of heave in auger
90—
I8 66
26 Artesian groundwater encountered
95 27
28
❑
rc
a
z
a
w
x
U
W
H
O
w
O
i
w
O
r
(7
rc
w
w
z
z
w
O
E
E
r
m
❑
a
O
q�
F
z
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-2 (continued)
Project: Potlatch Transmission Lines North Bay Crossing
E Project Location: Mason County, Washington
GEOENGINEER FigureA-4
Project Number: 4682-028-01 Sheet 3 of 3
Start End Total Logged By MM Drilling
Drilled 8/17/2009 8/17/2009 Depth(ft) 53 Checked By Driller Holocene Drilling Method Mud Rotary
Surface Elevation(ft) Undetermined Hammer 140-Ib/30-in Autohammer Drilling Truck Mounted Mobile B-59
Vertical Datum Data Equipment
Easting(X) -122.819027 System Groundwater
Northing(Y) 47.389968 Datum WGS84 Depth to
Date Measured Water Elevation(ft)
[Notes:
FIELD DATA
m
E
MATERIALco
„o�
REMARKS
o m w DESCRIPTION
o N Z n y o o — E.N w m o' o`o Zvi o CIO inF-
0 ML Brown silt with sand,shell fragments and
organics(very soft,wet)(marine/alluvial
deposits)
5 18 0 1 uo %F=75
%F
10 3 I 2
SM Gray silty fine to coarse sand with shell
fragments(very loose,wet)(marine/alluvial
deposits)
15 18 14 3
4 SP-SM Gray fine to coarse sand with gravel,silt and
trace shell fragments(medium dense,wet)
(marine/alluvial deposits)
SM Gray silty fine to coarse sand with gravel and
o trace shell fragments(loose,wet)
0 20 12 6 (marine/alluvial deposits) IS %F=13
a %F
x
i
U
W
o
ML Brown silt with sand,organics and occasional
organics(very soft,wet)(marine/alluvial
o deposits)
o 25 I8 0 6 54 %F=76
rc %F
w
z
z
w
o
NIL
Gray silt with sand and gravel(medium stiff,
E wet)(glaciolacustrine silt)
30 18 6 7
E
0
a'
GM Gray silty fine to coarse gravel with sand(very
dense,wet)(glacial till)
u 35
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-3
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
GEOENGINEERS� j yFigureA-5
Project Number: 4682-028-01 Sheet 1 of 2
FIELD DATA
w l " a E m o MATERIAL
w o '0 z .@ o r REMARKS
o o m �, �, DESCRIPTION
= 2 0 3 0 v a p
w o tr m c°� inr 0U 0
35 18 71
Drill chatter
SNt Gray silty fine to coarse sand with gravel(very
dense,wet)(glacial till)
40 12 62 9
o GP-GM —Gray fine to coarse gravel sa with nd and silt
o (very dense,wet)(glacial till)
45H 0
12 106 10 o Driller notes heave in auger
0
0
0
0
0
0
0
6 504" 11 0
0
0
0
0
a
0
z
a
N
S
U
w
H
O
w
O
ti
O
m
K
W
2
O
Z
O
w
E
ti
E
m
0
'a
z
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring B-3 (continued)
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
C7EOENGINEER FigureA-5
Project Number: 4682-028-01 Sheet 2 of 2
Start End Total 71 5 Logged By CAJ Driller Holocene Drilling, Inc. Drilling Hollow-stem Auger
Drilled 12/29/2011 12/29/2011 Depth(ft) Checked By MM Method
Surface Elevation(ft) 76.0 Hammer Autohammer Drilling Diedrich D-50 Track Rig
Vertical Datum Data 140(lbs)/30(in)Drop Equipment
Easting(X) -122.810893 System Groundwater
Northing(Y) 47.389685 Datum NAD83 Depth to
Date Measured Water ft Elevation(ft)
Notes: Auger Data:3'/4 inch I.D.,7 inch O.D. 12/29/2011 8.2 67.8
FIELD DATA
w - E 6 I; o MATERIAL
o w 8 m DESCRIPTION REMARKS
io r o v u — c L a'y 5 m
d y U 3 m E N N O m 0 0 Z'U
lL c m 0 U)H ?i � 0U
0 6 5 o GP-GM Brown fine to coarse gravel with sand and silt
(loose,moist)(fill) ————————J
ML `————————
6 51 2 Brown sandy silt with gravel and occasional fine 15
organics(very stiff,moist)(reworked native
SP-SM soil)
12 30 3A Brown fine to medium sand with silt and
SP-SM occasional gravel(medium dense,wet) / %F=13
SA _(recessional lake marginal outwash)
5-1 10 8 4 Brown medium sand with silt and fine gravel
10 (loose,moist)(recessional lake marginal
outwash)
13 17 5 No free water in sample
S Grades to medium dense
10-118 21 6A
6h
6B
SM Light brown silty fine to medium sand(dense,
wet)
15 14 39 2 13 %F=16
by %F
a
a
a
z 20 16 52 8 Grades to very dense
mi y5
x
U
w
o
O
w
O
w
C7
0
r,
25 18 64 9
w
Z 5°
z
o
a
E Occasional gravel
� 30 18 60 10
E A5
m
O
'a
O
4
? 35
u
Note:See Figure A-1 for explanation of symbols.
s
s
a
Log of Boring BA
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
GMENGINEERS FigureA-6
Project Number: 4682-028-02 Sheet 1 of 2
FIELD DATA
m
a
E MATERIAL
o w o z J ° a i REMARKS
0 9 DESCRIPTION „ -
cc w z i; N m r- z.y =2 o
o o o � oo z�
w o of m V mH 0 00 M() o a
35 17 56nil o =
ap SA
40 18 54 12 Approximately 6 inches of heave
ph
SP-SM Brown with slight orange staining fine to
medium sand with silt(very dense,wet)
(advance outwash)
45 17 72 13 20 Approximately 3 inches of heave
pp %F %F=11
12 50/6" 14 Approximately 7 inches of heave
tih
55 10 65 15 Approximately 4 inches of heave
ry0
60 18 58 16 21 Approximately 4 inches of heave
y ioF %F=9
a
Z
N
2
U
W
f
�I
65 11 50/5" 17 Approximately 12 inches of heave
o �p
N
K
Z
U
Z
o
o
70 18 79 18 Approximately 8 inches of heave
e
m
0
a'
Z
(7
Note:See Figure A-1 for explanation of symbols.
s
a
Log of Boring B-4 (continued)
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
E GEOENGINEER FigureA-6
Project Number: 4682-028-02 Sheet 2 of 2
Start and Total 71.34 Logged By CAJ Driller Holocene Drilling,Inc. Drilling Hollow-stem Auger
Drilled 12/30/2011 12/30/2011 Depth(ft) checked By MM Method
Surface Elevation(ft) 93.0 Hammer Autohammer Drilling Diedrich D-50 Track Rig
Vertical Datum Data 140(lbs)/30(in)Drop Equipment
Easting(X) -122.827694 System Groundwater
Northing(Y) 47.390824 Datum NAD83 Depth to
Date Measured Water ft Elevation(ft)
Notes: Auger Data:3%inch I.D.,7 inch O.D. 12/30/2011 3.3 89.7
FIELD DATA
w - E E s MATERIAL
w o y z o r REMARKS
o o m DESCRIPTION m
't-' Z O ul m E C ..0. Q 7 y m p
N O N O f0 N N f0 O
to o c m v U)H 20 ❑8
0I GM Brown silty fine to coarse gravel with sand and
6 1 occasional roots and cobbles(dense,moist) Grab sample of cuttings
(weathered glacial till) P g
6 40 2 s
SM Mottled Tight brown snd orange silty fine to
coarse sand with gravel(very dense,wet)
5 12 50/6" 3 (glacial till) I I %F=33
SA
mh 11 50/5" 4 Without mottling
10 10 50/4" 5
�o
15 18 78 6 II %F=38
SA
�h
a
20 10 50/5" 7
N
1
S
V
f
O
w
O .�O
W
O
ti
O
O
25 9 50/3,, 8
w
w
z
SP-SM Light brown fine to medium sand with silt(very
o dense,wet)(advance outwash)
w
m bh
E
ti
� 30
14 74 9
E
0
4 0�
4
3 35
0
Note:See Figure A-1 for explanation of symbols.
s
a
Log of Boring B-5
Project: Potlatch Transmission Lines North Bay Crossing
Project Location: Mason County, Washington
C]EOENGINEERS � FigureA-7
Project Number: 4682-028-02 Sheet 1 of 2
FIELD DATA
d
c w o y z MATERIAL o REMARKS
o o m N m DESCRIPTION
t o N V — C a� L a— c d
2 3 m a y N a o
N y a> p v m•� m o
W 0 c 00 U' 00 U n
35 14 83 Lo %F=12
%F
h�
40 14 66 11
T. Light brown silty fine to medium sand(very
dense,wet)(advance outwash)
yo
45 15 77 12
hh
13 65 F 13 °„: 16
a° I!
55 16 74 14
-- ------------------
Light brown fine to medium sand with silt(very
dense,wet)(advance outwash)
60 15 85 15
0
a
0
z
a
U
H
O
w
O
i
F65 17 62 %F 19 %F=7
0
o_
w
z
0
m 70 16 96 17 Approximately 4 inches of heave
a
io
a
U
4
4
z
R Note:See Figure A-1 for explanation of symbols.
s
a
Log of Boring B-5 (continued)
C
Project: Potlatch Transmission Lines North Bay Crossing
E Project Location: Mason County, Washington
C.7EOENGINEERS FigureA-7
Project Number: 4682-028-02 Sheet 2 of 2
T
8
Q
T U
O Q
O O
z (o i
O "cn
H
Q >
m m
N -N 3 w
g -0 -a 3
C C C -p
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N
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o 0 0
zm` m` m` cD
w -_
W = �
N_ w
w J O
w
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m
0 W
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Z Z ¢ � o L22 �
1 r Q O 0
x �
o af
C w
W 2
H10 Y lo� d m co L
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(� LLI
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00,
w
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(V
co
GEoENGINEER S SIEVE ANALYSIS RESULTS
co
FIGURE A-8
` - APPENDIX B
Report Limitations and Guidelines for Use
400
.r
_. -
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
APPENDIX B
REPORT LIMITATIONS AND GUIDELINES FOR USEI
This appendix provides information to help you manage your risks with respect to the use of this
report.
Geotechnical Services are Performed for Specific Purposes, Persons and Projects
This report has been prepared for the exclusive use of Tacoma Public Utilities, and their authorized
agents, including Electric Power Systems, Inc., BergerABAM and David Evans Associates. This
report is not intended for use by others, and the information contained herein is not applicable to
any area outside the described project area.
GeoEngineers structures our services to meet the specific needs of our clients. For example, a
geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs
of a construction contractor or even another civil engineer or architect that are involved in the
same project. Because each geotechnical or geologic study is unique, each geotechnical
engineering or geologic report is unique, prepared solely for the specific client and project site. Our
report is prepared for the exclusive use of our Client. No other party may rely on the product of our
services unless we agree in advance to such reliance in writing. This is to provide our firm with
reasonable protection against open-ended liability claims by third parties with whom there would
otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and
budget, our services have been executed in accordance with our Agreement with the Client and
generally accepted geotechnical practices in this area at the time this report was prepared. This
report should not be applied for any purpose or project except the one originally contemplated.
A Geotechnical Engineering or Geologic Report is Based on a Unique Set of Project-
Specific Factors
This report has been prepared for the Potlatch Transmission Lines North Bay Crossing Phase II
Assessment located in Mason County, Washington. GeoEngineers considered a number of unique,
project-specific factors when establishing the scope of services for this project and report. Unless
GeoEngineers specifically indicates otherwise,do not rely on this report if it was:
■ not prepared for you,
■ not prepared for your project,
■ not prepared for the specific site explored, or
■ completed before important project changes were made.
For example,changes that can affect the applicability of this report include those that affect:
■ the function of the proposed structure;
■ elevation, configuration, location,orientation or weight of the proposed structure;
1 Developed based on material provided by ASFE,Professional Firms Practicing in the Geosciences;www.asfe.org.
GEoENGINEERS� May 2,2012 Page B-1
File Na.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County.Washington
■ composition of the design team; or
■ project ownership.
If important changes are made after the date of this report, GeoEngineers should be given the
opportunity to review our interpretations and recommendations and provide written modifications
or confirmation, as appropriate.
Subsurface Conditions Can Change
This geotechnical or geologic report is based on conditions that existed at the time the study was
performed. The findings and conclusions of this report may be affected by the passage of time, by
manmade events such as construction on or adjacent to the site, or by natural events such as
floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers
before applying a report to determine if it remains applicable.
Most Geotechnical and Geologic Findings are Professional Opinions
Our interpretations of subsurface conditions are based on field observations from widely spaced
sampling locations at the site. Site exploration identifies subsurface conditions only at those
points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field
and laboratory data and then applied our professional judgment to render an opinion about
subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes
significantly,from those indicated in this report. Our report,conclusions and interpretations should
not be construed as a warranty of the subsurface conditions.
Geotechnical Engineering Report Recommendations are Not Final
Do not over-rely on the preliminary construction recommendations included in this report. These
recommendations are not final, because they were developed principally from GeoEngineers'
professional judgment and opinion. GeoEngineers' recommendations can be finalized only by
observing actual subsurface conditions revealed during construction. GeoEngineers cannot
assume responsibility or liability for this report's recommendations if we do not perform
construction observation.
Sufficient monitoring, testing and consultation by GeoEngineers should be provided during
construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed
during the work differ from those anticipated, and to evaluate whether or not earthwork activities
are completed in accordance with our recommendations. Retaining GeoEngineers for construction
observation for this project is the most effective method of managing the risks associated with
unanticipated conditions.
A Geotechnical Engineering or Geologic Report Could be Subject to Misinterpretation
Misinterpretation of this report by other design team members can result in costly problems. You
could lower that risk by having GeoEngineers confer with appropriate members of the design team
after submitting the report. Also retain GeoEngineers to review pertinent elements of the design
team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or
Page B-2 May2,2012 i GeoEngineers,Inc.
Hie No.4682-028-02
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
geologic report. Reduce that risk by having GeoEngineers participate in pre-bid and
preconstruction conferences, and by providing construction observation.
Do Not Redraw the Exploration Logs
Geotechnical engineers and geologists prepare final boring and testing logs based upon their
interpretation of field logs and laboratory data. To prevent errors or omissions,the logs included in
a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural
or other design drawings. Only photographic or electronic reproduction is acceptable, but
recognize that separating logs from the report can elevate risk.
Give Contractors a Complete Report and Guidance
Some owners and design professionals believe they can make contractors liable for unanticipated
subsurface conditions by limiting what they provide for bid preparation. To help prevent costly
problems, give contractors the complete geotechnical engineering or geologic report, but preface it
with a clearly written letter of transmittal. In that letter, advise contractors that the report was not
prepared for purposes of bid development and that the report's accuracy is limited; encourage
them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of
information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors
have sufficient time to perform additional study. Only then might an owner be in a position to give
contractors the best information available, while requiring them to at least share the financial
responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated
conditions should be included in your project budget and schedule.
Contractors are Responsible for Site Safety on their Own Construction Projects
Our geotechnical recommendations are not intended to direct the contractor's procedures,
methods, schedule or management of the work site. The contractor is solely responsible for job
site safety and for managing construction operations to minimize risks to on-site personnel and to
adjacent properties.
Read These Provisions Closely
Some clients, design professionals and contractors may not recognize that the geoscience
practices (geotechnical engineering or geology) are far less exact than other engineering and
natural science disciplines. This lack of understanding can create unrealistic expectations that
could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory
"limitations" provisions in our reports to help reduce such risks. Please confer with GeoEngineers
if you are unclear how these "Report Limitations and Guidelines for,Use" apply to your project or
site.
Geotechnical, Geologic and Environmental Reports Should not be Interchanged
The equipment, techniques and personnel used to perform an environmental study differ
significantly from those used to perform a geotechnical or geologic study and vice versa. For that
reason, a geotechnical engineering or geologic report does not usually relate any environmental
findings, conclusions or recommendations; e.g., about the likelihood of encountering underground
/- May 2,2012 Page B-3
GEoENGINEERS/
File Na.4682-028-02 -
60%DESIGN POTLATCH TRANSMISSION LINES NORTH BAY CROSSING Mason County,Washington
storage tanks or regulated contaminants. Similarly, environmental reports are not used to address
geotechnical or geologic concerns regarding a specific project.
Biological Pollutants
GeoEngineers' Scope of Work specifically excludes the investigation, detection, prevention, or
assessment of the presence of Biological Pollutants in or around any structure. Accordingly, this
report includes no interpretations, recommendations, findings, or conclusions for the purpose of
detecting, preventing, assessing, or abating Biological Pollutants. The term "Biological Pollutants"
includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their
byproducts.
Page B-4 May 2,2012 GeoEngineers,Inc.
File No.4682-028-02