march 20, 2018 - seattle
TRANSCRIPT
Seattle, Washington 98121
Re: Preliminary Geotechnical Report for Master Use Permit (MUP) Submittal
3rd and Cherry
This report provides preliminary geotechnical information to support the Master Use Permit (MUP)
application for the 3rd and Cherry project located at 601 4th Avenue in Seattle, Washington. The project
site will occupy the block bounded by 4th Avenue, James Street, 3rd Avenue, and Cherry Street
(Figure 1). Current development plans are to construct a 708-foot-tall building with five levels of below
grade parking.
Bosa Development US LLC 19357-00
March 20, 2018 Page 2
The site is currently unoccupied and partially excavated because a prior development was not
completed. This block was previously occupied by the Seattle Public Safety Building, which was
demolished in 2005. Demolition removed both the above- and below-grade structure, except that the
existing below-grade perimeter walls were temporarily shored with tieback anchors and counterfort
structures to provide support after removal of the basement floors and columns. The existing bottom of
excavation ranges from about elevation 54 feet on the west (3rd Avenue) side of the block to about
76 feet on the east (4th Avenue) side of the block. The bottom floor slab of the demolished building is
still present and providing support to the bottom of the existing walls.
Subsurface Soil and Groundwater Conditions
Our interpretation of subsurface conditions is based on historical geotechnical borings at the locations
shown on Figure 2. The logs of these borings are attached to this report.
Figure 2. Historical Geotechnical Boring Locations
Bosa Development US LLC 19357-00
March 20, 2018 Page 3
Subsurface soil conditions are expected to consist of as much as 26 feet of fill, consisting of very loose to
medium dense, slightly silty to silty sand with variable amounts of gravel, brick, and concrete fragments,
overlying glacially overridden nonglacial and glacial deposits generally consisting of very stiff to hard
fine-grained deposits and very dense coarse-grain deposits.
Perched water is expected at the interface of the fill and native glacially overridden soils. Previously
documented water levels measured in groundwater observation wells during March 2008 measured
water levels at about elevation 17 feet, which is below the planned depth of excavation.
In addition to the existing subsurface explorations, we recommend drilling one additional boring below
the core of the proposed building.
Support of Excavation
Based on review of the architectural drawings, and assuming the excavation will extend at least 5 feet
below the finished floor elevation, the currently planned excavation is expected to extend down to
about elevation 35 feet, which is about 45 feet below 3rd Avenue and about 75 feet below 4th Avenue.
The planned excavation will extend below the current bottom of the excavation by roughly 20 to 40
feet, and so will require additional shoring. Existing shoring elements, such as tiebacks retaining the
existing basement walls, could be re-used and/or supplemented with new tiebacks. Where existing
basement walls will not be integrated into the new shoring, conventional soldier piles with tieback
anchors and wood lagging is appropriate. Adequate clearance between the existing underground
structures will need to be maintained as required by their owners. We recommend meeting with SDOT,
King County Metro, and BNSF as soon as possible during schematic design to communicate and receive
feedback on the proposed shoring plan. In addition to the tunnels and bus station, easements will be
required for any shoring element extending beyond the property boundaries. Shoring elements can
typically be installed and left below city streets and alleys provided the elements are de-tensioned after
construction and components within 4 feet of the ground surface are removed.
As part of design, surcharge loads on the new shoring and building will need to be investigated as well as
the potential for the new construction imparting new loads on existing structures, such as tunnels and
basements.
Soldier Piles, Tieback Anchors, Wood Lagging
Soldier piles consist of steel W or H sections installed in predrilled holes typically on a center-to-center
spacing of about 8 feet and extending about 10 feet below the bottom of the excavation. The holes are
typically backfilled with low-strength concrete.
Tieback anchors are drilled from the face of the excavation/soldier pile wall at an angle of about
20 degrees down from the horizontal. They are typically spaced about 8 feet to 10 feet vertically, and
Bosa Development US LLC 19357-00
March 20, 2018 Page 4
horizontally at every soldier pile. Tiebacks supporting excavations of this depth range from 40 to 80 feet
long and include an unbonded or “no-load” length near the wall, and a bonded length farther back. All
wall loads are supported in the bonded length. Tieback holes are backfilled with concrete or are
pressure grouted, and post-tensioned. They serve as anchors to the vertical wall that wants to deflect
into the excavation as the excavation deepens. Each tieback anchor is proof tested to 130% of the
design load, and a small percental of the anchors are verification tested to 200% of the design soil
pullout values.
Timber lagging, usually 3 or 4 inches thick, is installed between the soldier piles to maintain excavation
face stability as the excavation deepens. Geosynthetic drainage mats should be placed adjacent to the
lagging to avoid water build-up behind the foundation walls. The basement foundation wall is then cast
(or shotcreted) directly against the lagging and drainage mats.
Significant Underground Structures
The site is bordered on the west (3rd Avenue) by the Pioneer Square bus station and bus tunnels and is
bordered along the east (4th Avenue) by the BNSF railroad tunnel (aka BNR tunnel, aka Great Northern
Tunnel).
The BNSF tunnel centerline is located approximately along the centerline of 4th Avenue and is about
39 feet wide, placing the east tunnel wall about 20 feet east of the east shoring wall. The top of the
tunnel is at about elevation 49 feet and the bottom of the tunnel is at about elevation 13 feet.
Therefore, the planned excavation will extend roughly 15 feet below the top elevation of the tunnel and
20 feet above the bottom of the tunnel.
Along 3rd Avenue most of the existing basement wall is immediately adjacent to the Pioneer Station
walls; however, the northern 74 feet of the wall along 3rd Avenue is beyond the station and will be
adjacent to the eastern tunnel of the King County Metro twin bored tunnels. The clear space between
the west shoring wall and the east edge of the eastern bored tunnel is about 12 feet. The bottom of the
bus station is about elevation 10 feet. The top and bottom elevations of the bored tunnels are roughly
35 feet and 15 feet, respectively, along the northern 74 feet of the excavation along 3rd Avenue. Thus,
the bottom of excavation along 3rd Avenue is expected to extend about 25 feet above the bottom of the
Pioneer Square Station structure, and to be at about the same elevation as the top of the bored tunnels.
Foundation Support
Foundation soils are expected to be predominantly very stiff to hard slightly clayey to clayey silt with
layers of slightly silty to silty sand. Zones of very dense gravely and sandy soils are also likely to be
encountered, but to a lesser extent.
Bosa Development US LLC 19357-00
March 20, 2018 Page 5
Feasible foundation options include shallow spread footings and/or large mat foundations. Deep
foundations, including drilled shafts are also feasible if they are required to mitigate potential impacts
on existing underground structures. The lowest level floor can be constructed as a slab-on-grade.
Permanent Dewatering
Perched groundwater should be expected below the fill soils down to about 26 feet below street grade
and the regional groundwater table may be at about elevation 17 feet, based on previously reported
groundwater measurements. Groundwater elevations will be updated during design.
Based on the expected bottom of excavation at elevation 35 to 45 feet, previously measured
groundwater elevation, soil conditions, and our experience on similar projects in the vicinity of the
proposed building, the excavation is expected to encounter a relatively low volume of groundwater and
full-depth permanent dewatering is likely feasible. This is a much lower cost alternative compared to
waterproofing the building perimeter and designing for hydrostatic pressures.
Permanent Subgrade Walls
The permanent wall must support any surcharge loads from the weight of the surrounding buildings.
Working with the structural engineer and the shoring designer, Hart Crowser can estimate the
surcharges and the additional load supporting requirements.
Seismic Design
Hart Crowser will conduct a performance-based seismic design with external peer review, as required by
the City of Seattle. We will develop the site-specific seismic hazard and select and scale earthquake
ground motion records of acceleration for input into the structural engineer’s seismic analysis. For soil
shear wave velocity, we intend to use existing downhole shear wave velocity measurements from
Boring B-3.
Four parameters will be used to construct a code-based spectrum. They are the Site Class, the mapped
values of the short-period and 1-second spectral response accelerations (SS and S1), and the long-period
transition period (TL). These parameters were obtained from the USGS Design Maps Detailed Report for
ASCE 7-10 Site Class C. Factors used in the development of this spectrum are shown in Table 1.
Bosa Development US LLC 19357-00
March 20, 2018 Page 6
Table 1 – Spectral Acceleration Response Parameters for MCER
Parameter Design Parameters
Environmentally Critical Areas
We reviewed the Seattle Department of Construction and Inspection GIS and did not observe any
mapped Environmentally Critical Areas (ECAs) on the site.
Conclusion
Based on our current understanding of the proposed construction, the expected subsurface conditions,
and our experience on similar projects in the region, it is our opinion that the planned project is
geotechnically feasible.
SCS-1 SCS-2
2/13/2008 50(3) (16.8)
3/24/2008 39.5 (17.1) 50.2 (16.6) Notes:
3. Time of drilling bgs = below ground surface
2. Water depths were measured from the ground surface.
Water Depth (Elevation) (2) Measured in Groundwater Observation Well (feet)
1. Water readings were collected by Shannon & Wilson personnel.
Date
Hard
Trace constituents compose 0 to 5 percent of the soil (i.e., slightly silty SAND, trace of gravel).
Sheet 1 of 2
COARSE-GRAINED SOILS
Very dense
RELATIVE DENSITY
#4 to 3/4 inch (5 to 19 mm) 3/4 to 3 inches (19 to 76 mm)
3 to 12 inches (76 to 305 mm)
> 12 inches (305 mm)
Damp but no visible water
Visible free water, from below water table
SHANNON & WILSON, INC.
FINES
Minor constituents compose 12 to 50 percent of the soil and precede the major constituents (i.e., silty SAND). Minor constituents preceded by "slightly" compose 5 to 12 percent of the soil (i.e., slightly silty SAND).
WELL AND OTHER SYMBOLS
#200 to #40 (0.08 to 0.4 mm) #40 to #10 (0.4 to 2 mm) #10 to #4 (2 to 5 mm)
BOULDERS
MOISTURE CONTENT DEFINITIONS
Slough
Bedrock
Seal
* Unless otherwise noted, sand and gravel, when present, range from fine to coarse in grain size.
COBBLES
SAND*
Not applicable or not available
Non plastic
Outside diameter
Water level indicator
MAJOR constituents compose more than 50 percent, by weight, of the soil. Major consituents are capitalized (i.e., SAND).
< #200 (0.08 mm)
Shannon & Wilson, Inc. (S&W), uses a soil classification system modified from the Unified Soil Classification System (USCS). Elements of the USCS and other definitions are provided on this and the following page. Soil descriptions are based on visual-manual procedures (ASTM D 2488-93) unless otherwise noted.
ATD
Elev.
ft
FeO
MgO
HSA
ID
in
lbs
Mon.
N
NA
NP
OD
OVA
PID
ppm
PVC
SS
SPT
USC
WOH
WOR
WLI
200 sieve)
passes the No. 4 sieve)
(liquid limit less than 50)
(liquid limit 50 or more)
(50% or more passes the No.
200 sieve)
MH
SP
GP
GM
GC
SC
Organic
Inorganic
SM
Sands
Clayey sands, sand-clay mixtures
Inorganic silts of low to medium plasticity, rock flour, sandy silts, gravelly silts, or clayey silts with slight plasticity
Sheet 2 of 2
SOILS
OL
Peat, humus, swamp soils with high organic content (see ASTM D 4427)
(less than 5% fines)
Silty gravels, gravel-sand-silt mixtures
Geotechnical and Environmental Consultants SHANNON & WILSON, INC.
Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays
Inorganic clays or medium to high plasticity, sandy fat clay, or gravelly fat clay
Inorganic silts, micaceous or diatomaceous fine sands or silty soils, elastic silt
Inorganic
Silty sands, sand-silt mixtures
fraction retained on No. 4 sieve)
MAJOR DIVISIONS
GROUP/GRAPHIC SYMBOL TYPICAL DESCRIPTION
CH
OH
NOTES
1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, slightly silty fine SAND) are used for soils with between 5% and 12% fines or when the liquid limit and plasticity index values plot in the CL-ML area of the plasticity chart.
2. Borderline symbols (symbols separated by a slash, i.e., CL/ML, silty CLAY/clayey SILT; GW/SW, sandy GRAVEL/gravelly SAND) indicate that the soil may fall into one of two possible basic groups.
ML
CL
Gravels
SW
(more than 12% fines)
(less than 5% fines)
UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) (From ASTM D 2487-98 & 2488-93)
NOTE: No. 4 size = 5 mm; No. 200 size = 0.075 mm
3 /2
4 /2
0 0
trace of silt; moist; wet below 5 feet, slight
odor/sheen at 5.0 feet; (Fill) SP/SP-SM.
Hard, gray-green, silty CLAY; moist; (Qpnl)
massive; CL.
clayey SILT and very dense, silty, fine
SAND to fine sandy SILT; moist; scattered
organic fragments, layer of peat from 12.5
to 12.7 feet, abundant organics from 17 to
22 feet, trace of gravel below 25 feet;
(Qpnl) ML/SM.
CLAY; moist; (Qpnl) ML/CL/CH.
slightly silty to silty, fine to medium SAND;
moist; scattered layers of silty sand,
abundant white pumice fragments at 65
feet; (Qpnf) SP-SM/SM.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-2
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
PT.
ML/OL.
moist; massive; (Qpnf) SM.
CLAY, trace of fine sand; moist; scattered
pumice; (Qpnl) ML.
moist; (Qpnf) SM.
BOTTOM OF BORING
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-2
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
clayey SILT; moist; scattered peat
interbeds and roots, scattered iron-oxide
staining below 15 feet; (Qpnl) ML/PT.
Very dense or hard, gray to brown, silty,
fine SAND, trace of clay; moist; interbedded
with layers of silt; (Qpnf) SM/ML.
Hard, gray to dark brown, slightly clayey to
clayey SILT; moist; scattered peat layers
and woody organics, scattered fine sandy
seams; (Qpnl) ML.
medium SAND; moist; scattered silt clasts;
(Qpnf) SM/ML.
scattered sand seams, scattered organic
fragments; (Qpnl) ML.
to silty, fine to medium SAND; moist to wet;
massive; locally only trace of silt, abundant
white pumice fragments below 60 feet;
(Qpnf) SP-SM/SM/SP.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-3
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
(Qpnl) OL/PT.
clayey to clayey SILT and very dense, gray,
silty, fine to medium SAND; moist to wet;
locally organic, scattered organics and
vivianite crystals; (Qpnl) ML/SM/OL.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-3
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
trace of fine sand; moist; interbedded with
layers of peat and silty, fine sand, scattered
organics, scattered oxidation, only trace of
clay below 7.5 feet; (Qpnl) ML/SM.
Very dense, brown, slightly silty to silty, fine
to medium SAND; moist; locally trace of
gravel; (Qpnf) SP-SM/SM.
organics; (Qpnl) CL.
moist; abundant dark gray, fine sand
partings, abundant organics, scattered
Very dense, gray, silty, fine SAND; moist;
scattered to abundant organics, scattered
pumice fragments; (Qpnf) SM.
silty CLAY; moist; scattered organics and
vivianite crystals; (Qpnl) ML/CL.
slightly silty to silty, fine to medium SAND;
moist; (Qpnf) SP-SM/SM.
gravel; moist; locally slightly clayey (Qpnf)
SM.
77
79/12"
83/12"
76
50/4"
83/11"
67
89
50/5"
80
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
0
0
SAND, trace of silt, trace of fine gravel;
moist; (Qpnf) SP.
organic SILT; moist; (Qpnl) OL.
Hard, dark brown PEAT; moist; (Qpnl) PT.
Very dense, gray, silty, fine to medium
SAND; moist; brown silt layers, abundant
white pumice fragments; (Qpnf) SM.
Hard, gray, slightly fine sandy, slightly
clayey SILT; moist; abundant seams and
interbeds of silty fine sand, locally only
trace of sand, locally only trace of clay,
locally interbedded with layers of silty, fine
sand; (Qpnl) ML/SM.
grading to slightly silty to silty, fine to
medium SAND; moist; abundant silt seams
at top, only trace of silt at bottom; (Qpnf)
SM/SP-SM.
sandy SILT interbedded with very dense,
50/5"
74
70
50/5.5"
94/10"
82
50/5.5"
85/10"
76
50/5.5"
50/5"
50/5"
16
17
18
19
20
21
22
23
24
25
26
27
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
0
0
moist; locally laminated, locally chaotic
texture, scattered organics in silt layers;
(Qpnl) ML/SM.
fine to medium SAND interbedded with
hard, gray, fine sandy, clayey SILT; moist;
locally chaotic texture with clayey rip-up
clasts; (Qpnf) SP-SM/SM/ML.
moist; laminated, abundant fine sand
partings; (Qpnl) CL/CH.
organic-rich seams; (Qpnf) SM/ML/CL.
moist; laminated, interbed of moist to wet,
slightly clayey, fine sandy silt; (Qpnl)
CL/ML.
interbedded with hard, gray, silty CLAY or
clayey SILT, trace of fine sand; moist;
abundant organics in clay and silt beds;
(Qpnf) SM/ML/CL.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
light gray silt partings, scattered
slickensides, locally diced/blocky texture;
feet.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
CONCRETE.
GW.
disturbed appearance, brick debris; (Fill)
ML.
moist; layers of very soft, wet, clayey silt,
numerous cobbles at 4 to 8 feet, locally
only trace of silt; (Fill) SP-SM/SP.
Very loose to loose, brown-gray, slightly
silty SAND; moist; wet below 20 feet,
scattered clayey silt clasts and gravel,
locally only trace of silt; (Fill) SP-SM/SP.
CONCRETE.
fine organics, locally laminated, locally only
trace of clay; (Qpnl) ML/SM.
Very dense light brown, clean, fine SAND;
moist; massive; (Qpnf) SP.
depth of 23.5 feet. Drillers were able
to penetrate concrete using an
8-inch auger bit. Drillers noted that
the borehole may have intersected
the edge of a concrete pad, which
made drilling easier than anticipated.
(WOH)
65
82
91/11"
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
SP-SM/GP-GM.
brown, slightly gravelly to gravelly, silty, fine
to medium SAND; moist; wet below 28.5
feet, voids, wood debris, and very loose
material between 26 and 36 feet; (Fill) SM.
Hard, gray to dark brown, slightly clayey
SILT; moist; locally laminated, scattered
compressed peat layers; (Qpnl) ML.
Very dense, light brown, fine SAND, trace
of silt; wet; massive; (Qpnf) SP.
Hard, gray to dark brown, slightly clayey to
clayey SILT; moist; scattered compressed
peat layers and fine organics; (Qpnl) ML.
(WOH)
74
50/5"
52/6"
88
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 2
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
made during vacuum excavation.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 2
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
scattered roots; (Fill) SP-SM/SW-SM.
SILT; moist; scattered iron-oxide-stained
sand seams; (Fill) CL/ML.
silty, sandy GRAVEL; moist to wet; (Fill)
GM.
sand seams, scattered iron-oxide stains;
(Fill) CL.
SAND to silty, sandy GRAVEL; moist;
locally clayey; (Qpgm) SM/GM.
seams; (Qpgm) ML.
GRAVEL; moist; massive, locally slightly
clayey to clayey; (Qpgm) GM.
Very dense, gray, silty, gravelly SAND,
trace of clay; wet; massive, locally slightly
50/5"
52/6"
81
50/4"
50/4"
50/5"
50/4"
1
2
3
4
5
6
7
8
9
10
11
12
13
14
E
0.2
5.0
12.0
15.0
20.0
32.0
38.0
57.0
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
gravel; moist; (Qpgm/Qpgl) ML.
Very dense, gray-green-brown, slightly
GRAVEL; moist; (Qpgm) SM/GM.
silty to silty, fine to medium SAND; moist to
wet; massive; (Qpnf) SP-SM/SM.
massive; (Qpnl) ML.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
made during vacuum excavation.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 3 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
massive; (Fill) CL.
gravelly, sandy SILT to sandy SAND, trace
of clay; moist; compacted, slightly clayey to
clayey above 16.5 feet; (Qpgm) ML/SM.
Very dense, brown to light brown, slightly
silty to silty, fine to medium SAND; moist;
locally only trace of silt; (Qpnf)
SM/SP-SM/SP.
GRAVEL; wet; (Qpnf) GP-GM.
clayey SILT; moist; interbedded with layers
of peat and organic silt; (Qpnl) ML/OL/PT.
Very dense, brown to light brown, slightly
silty to silty SAND; moist; massive; (Qpnf)
SM/SP-SM.
74
65
87/11"
50/5"
50/6"
78
61
52/6"
50/6"
1
2
3
4
5
6
7
8
9
10
11
12
13
E
0.2
0.5
14.0
19.0
33.0
37.0
49.0
57.0
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
Very dense, silty, fine SAND grading to
slightly clayey SILT; moist; scattered
iron-oxide stains, slightly gravelly above
70.5 feet; (Qpnf) SM/ML.
SAND, trace of silt; moist to wet; (Qpnf) SP.
Very dense, brown and gray, silty, fine to
medium SAND; moist; locally slightly fine
gravelly, interbedded with layers of peat at
110 feet; (Qpnf) SM/PT.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 3 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
Re: Preliminary Geotechnical Report for Master Use Permit (MUP) Submittal
3rd and Cherry
This report provides preliminary geotechnical information to support the Master Use Permit (MUP)
application for the 3rd and Cherry project located at 601 4th Avenue in Seattle, Washington. The project
site will occupy the block bounded by 4th Avenue, James Street, 3rd Avenue, and Cherry Street
(Figure 1). Current development plans are to construct a 708-foot-tall building with five levels of below
grade parking.
Bosa Development US LLC 19357-00
March 20, 2018 Page 2
The site is currently unoccupied and partially excavated because a prior development was not
completed. This block was previously occupied by the Seattle Public Safety Building, which was
demolished in 2005. Demolition removed both the above- and below-grade structure, except that the
existing below-grade perimeter walls were temporarily shored with tieback anchors and counterfort
structures to provide support after removal of the basement floors and columns. The existing bottom of
excavation ranges from about elevation 54 feet on the west (3rd Avenue) side of the block to about
76 feet on the east (4th Avenue) side of the block. The bottom floor slab of the demolished building is
still present and providing support to the bottom of the existing walls.
Subsurface Soil and Groundwater Conditions
Our interpretation of subsurface conditions is based on historical geotechnical borings at the locations
shown on Figure 2. The logs of these borings are attached to this report.
Figure 2. Historical Geotechnical Boring Locations
Bosa Development US LLC 19357-00
March 20, 2018 Page 3
Subsurface soil conditions are expected to consist of as much as 26 feet of fill, consisting of very loose to
medium dense, slightly silty to silty sand with variable amounts of gravel, brick, and concrete fragments,
overlying glacially overridden nonglacial and glacial deposits generally consisting of very stiff to hard
fine-grained deposits and very dense coarse-grain deposits.
Perched water is expected at the interface of the fill and native glacially overridden soils. Previously
documented water levels measured in groundwater observation wells during March 2008 measured
water levels at about elevation 17 feet, which is below the planned depth of excavation.
In addition to the existing subsurface explorations, we recommend drilling one additional boring below
the core of the proposed building.
Support of Excavation
Based on review of the architectural drawings, and assuming the excavation will extend at least 5 feet
below the finished floor elevation, the currently planned excavation is expected to extend down to
about elevation 35 feet, which is about 45 feet below 3rd Avenue and about 75 feet below 4th Avenue.
The planned excavation will extend below the current bottom of the excavation by roughly 20 to 40
feet, and so will require additional shoring. Existing shoring elements, such as tiebacks retaining the
existing basement walls, could be re-used and/or supplemented with new tiebacks. Where existing
basement walls will not be integrated into the new shoring, conventional soldier piles with tieback
anchors and wood lagging is appropriate. Adequate clearance between the existing underground
structures will need to be maintained as required by their owners. We recommend meeting with SDOT,
King County Metro, and BNSF as soon as possible during schematic design to communicate and receive
feedback on the proposed shoring plan. In addition to the tunnels and bus station, easements will be
required for any shoring element extending beyond the property boundaries. Shoring elements can
typically be installed and left below city streets and alleys provided the elements are de-tensioned after
construction and components within 4 feet of the ground surface are removed.
As part of design, surcharge loads on the new shoring and building will need to be investigated as well as
the potential for the new construction imparting new loads on existing structures, such as tunnels and
basements.
Soldier Piles, Tieback Anchors, Wood Lagging
Soldier piles consist of steel W or H sections installed in predrilled holes typically on a center-to-center
spacing of about 8 feet and extending about 10 feet below the bottom of the excavation. The holes are
typically backfilled with low-strength concrete.
Tieback anchors are drilled from the face of the excavation/soldier pile wall at an angle of about
20 degrees down from the horizontal. They are typically spaced about 8 feet to 10 feet vertically, and
Bosa Development US LLC 19357-00
March 20, 2018 Page 4
horizontally at every soldier pile. Tiebacks supporting excavations of this depth range from 40 to 80 feet
long and include an unbonded or “no-load” length near the wall, and a bonded length farther back. All
wall loads are supported in the bonded length. Tieback holes are backfilled with concrete or are
pressure grouted, and post-tensioned. They serve as anchors to the vertical wall that wants to deflect
into the excavation as the excavation deepens. Each tieback anchor is proof tested to 130% of the
design load, and a small percental of the anchors are verification tested to 200% of the design soil
pullout values.
Timber lagging, usually 3 or 4 inches thick, is installed between the soldier piles to maintain excavation
face stability as the excavation deepens. Geosynthetic drainage mats should be placed adjacent to the
lagging to avoid water build-up behind the foundation walls. The basement foundation wall is then cast
(or shotcreted) directly against the lagging and drainage mats.
Significant Underground Structures
The site is bordered on the west (3rd Avenue) by the Pioneer Square bus station and bus tunnels and is
bordered along the east (4th Avenue) by the BNSF railroad tunnel (aka BNR tunnel, aka Great Northern
Tunnel).
The BNSF tunnel centerline is located approximately along the centerline of 4th Avenue and is about
39 feet wide, placing the east tunnel wall about 20 feet east of the east shoring wall. The top of the
tunnel is at about elevation 49 feet and the bottom of the tunnel is at about elevation 13 feet.
Therefore, the planned excavation will extend roughly 15 feet below the top elevation of the tunnel and
20 feet above the bottom of the tunnel.
Along 3rd Avenue most of the existing basement wall is immediately adjacent to the Pioneer Station
walls; however, the northern 74 feet of the wall along 3rd Avenue is beyond the station and will be
adjacent to the eastern tunnel of the King County Metro twin bored tunnels. The clear space between
the west shoring wall and the east edge of the eastern bored tunnel is about 12 feet. The bottom of the
bus station is about elevation 10 feet. The top and bottom elevations of the bored tunnels are roughly
35 feet and 15 feet, respectively, along the northern 74 feet of the excavation along 3rd Avenue. Thus,
the bottom of excavation along 3rd Avenue is expected to extend about 25 feet above the bottom of the
Pioneer Square Station structure, and to be at about the same elevation as the top of the bored tunnels.
Foundation Support
Foundation soils are expected to be predominantly very stiff to hard slightly clayey to clayey silt with
layers of slightly silty to silty sand. Zones of very dense gravely and sandy soils are also likely to be
encountered, but to a lesser extent.
Bosa Development US LLC 19357-00
March 20, 2018 Page 5
Feasible foundation options include shallow spread footings and/or large mat foundations. Deep
foundations, including drilled shafts are also feasible if they are required to mitigate potential impacts
on existing underground structures. The lowest level floor can be constructed as a slab-on-grade.
Permanent Dewatering
Perched groundwater should be expected below the fill soils down to about 26 feet below street grade
and the regional groundwater table may be at about elevation 17 feet, based on previously reported
groundwater measurements. Groundwater elevations will be updated during design.
Based on the expected bottom of excavation at elevation 35 to 45 feet, previously measured
groundwater elevation, soil conditions, and our experience on similar projects in the vicinity of the
proposed building, the excavation is expected to encounter a relatively low volume of groundwater and
full-depth permanent dewatering is likely feasible. This is a much lower cost alternative compared to
waterproofing the building perimeter and designing for hydrostatic pressures.
Permanent Subgrade Walls
The permanent wall must support any surcharge loads from the weight of the surrounding buildings.
Working with the structural engineer and the shoring designer, Hart Crowser can estimate the
surcharges and the additional load supporting requirements.
Seismic Design
Hart Crowser will conduct a performance-based seismic design with external peer review, as required by
the City of Seattle. We will develop the site-specific seismic hazard and select and scale earthquake
ground motion records of acceleration for input into the structural engineer’s seismic analysis. For soil
shear wave velocity, we intend to use existing downhole shear wave velocity measurements from
Boring B-3.
Four parameters will be used to construct a code-based spectrum. They are the Site Class, the mapped
values of the short-period and 1-second spectral response accelerations (SS and S1), and the long-period
transition period (TL). These parameters were obtained from the USGS Design Maps Detailed Report for
ASCE 7-10 Site Class C. Factors used in the development of this spectrum are shown in Table 1.
Bosa Development US LLC 19357-00
March 20, 2018 Page 6
Table 1 – Spectral Acceleration Response Parameters for MCER
Parameter Design Parameters
Environmentally Critical Areas
We reviewed the Seattle Department of Construction and Inspection GIS and did not observe any
mapped Environmentally Critical Areas (ECAs) on the site.
Conclusion
Based on our current understanding of the proposed construction, the expected subsurface conditions,
and our experience on similar projects in the region, it is our opinion that the planned project is
geotechnically feasible.
SCS-1 SCS-2
2/13/2008 50(3) (16.8)
3/24/2008 39.5 (17.1) 50.2 (16.6) Notes:
3. Time of drilling bgs = below ground surface
2. Water depths were measured from the ground surface.
Water Depth (Elevation) (2) Measured in Groundwater Observation Well (feet)
1. Water readings were collected by Shannon & Wilson personnel.
Date
Hard
Trace constituents compose 0 to 5 percent of the soil (i.e., slightly silty SAND, trace of gravel).
Sheet 1 of 2
COARSE-GRAINED SOILS
Very dense
RELATIVE DENSITY
#4 to 3/4 inch (5 to 19 mm) 3/4 to 3 inches (19 to 76 mm)
3 to 12 inches (76 to 305 mm)
> 12 inches (305 mm)
Damp but no visible water
Visible free water, from below water table
SHANNON & WILSON, INC.
FINES
Minor constituents compose 12 to 50 percent of the soil and precede the major constituents (i.e., silty SAND). Minor constituents preceded by "slightly" compose 5 to 12 percent of the soil (i.e., slightly silty SAND).
WELL AND OTHER SYMBOLS
#200 to #40 (0.08 to 0.4 mm) #40 to #10 (0.4 to 2 mm) #10 to #4 (2 to 5 mm)
BOULDERS
MOISTURE CONTENT DEFINITIONS
Slough
Bedrock
Seal
* Unless otherwise noted, sand and gravel, when present, range from fine to coarse in grain size.
COBBLES
SAND*
Not applicable or not available
Non plastic
Outside diameter
Water level indicator
MAJOR constituents compose more than 50 percent, by weight, of the soil. Major consituents are capitalized (i.e., SAND).
< #200 (0.08 mm)
Shannon & Wilson, Inc. (S&W), uses a soil classification system modified from the Unified Soil Classification System (USCS). Elements of the USCS and other definitions are provided on this and the following page. Soil descriptions are based on visual-manual procedures (ASTM D 2488-93) unless otherwise noted.
ATD
Elev.
ft
FeO
MgO
HSA
ID
in
lbs
Mon.
N
NA
NP
OD
OVA
PID
ppm
PVC
SS
SPT
USC
WOH
WOR
WLI
200 sieve)
passes the No. 4 sieve)
(liquid limit less than 50)
(liquid limit 50 or more)
(50% or more passes the No.
200 sieve)
MH
SP
GP
GM
GC
SC
Organic
Inorganic
SM
Sands
Clayey sands, sand-clay mixtures
Inorganic silts of low to medium plasticity, rock flour, sandy silts, gravelly silts, or clayey silts with slight plasticity
Sheet 2 of 2
SOILS
OL
Peat, humus, swamp soils with high organic content (see ASTM D 4427)
(less than 5% fines)
Silty gravels, gravel-sand-silt mixtures
Geotechnical and Environmental Consultants SHANNON & WILSON, INC.
Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays
Inorganic clays or medium to high plasticity, sandy fat clay, or gravelly fat clay
Inorganic silts, micaceous or diatomaceous fine sands or silty soils, elastic silt
Inorganic
Silty sands, sand-silt mixtures
fraction retained on No. 4 sieve)
MAJOR DIVISIONS
GROUP/GRAPHIC SYMBOL TYPICAL DESCRIPTION
CH
OH
NOTES
1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, slightly silty fine SAND) are used for soils with between 5% and 12% fines or when the liquid limit and plasticity index values plot in the CL-ML area of the plasticity chart.
2. Borderline symbols (symbols separated by a slash, i.e., CL/ML, silty CLAY/clayey SILT; GW/SW, sandy GRAVEL/gravelly SAND) indicate that the soil may fall into one of two possible basic groups.
ML
CL
Gravels
SW
(more than 12% fines)
(less than 5% fines)
UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) (From ASTM D 2487-98 & 2488-93)
NOTE: No. 4 size = 5 mm; No. 200 size = 0.075 mm
3 /2
4 /2
0 0
trace of silt; moist; wet below 5 feet, slight
odor/sheen at 5.0 feet; (Fill) SP/SP-SM.
Hard, gray-green, silty CLAY; moist; (Qpnl)
massive; CL.
clayey SILT and very dense, silty, fine
SAND to fine sandy SILT; moist; scattered
organic fragments, layer of peat from 12.5
to 12.7 feet, abundant organics from 17 to
22 feet, trace of gravel below 25 feet;
(Qpnl) ML/SM.
CLAY; moist; (Qpnl) ML/CL/CH.
slightly silty to silty, fine to medium SAND;
moist; scattered layers of silty sand,
abundant white pumice fragments at 65
feet; (Qpnf) SP-SM/SM.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-2
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
PT.
ML/OL.
moist; massive; (Qpnf) SM.
CLAY, trace of fine sand; moist; scattered
pumice; (Qpnl) ML.
moist; (Qpnf) SM.
BOTTOM OF BORING
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-2
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
clayey SILT; moist; scattered peat
interbeds and roots, scattered iron-oxide
staining below 15 feet; (Qpnl) ML/PT.
Very dense or hard, gray to brown, silty,
fine SAND, trace of clay; moist; interbedded
with layers of silt; (Qpnf) SM/ML.
Hard, gray to dark brown, slightly clayey to
clayey SILT; moist; scattered peat layers
and woody organics, scattered fine sandy
seams; (Qpnl) ML.
medium SAND; moist; scattered silt clasts;
(Qpnf) SM/ML.
scattered sand seams, scattered organic
fragments; (Qpnl) ML.
to silty, fine to medium SAND; moist to wet;
massive; locally only trace of silt, abundant
white pumice fragments below 60 feet;
(Qpnf) SP-SM/SM/SP.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-3
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
(Qpnl) OL/PT.
clayey to clayey SILT and very dense, gray,
silty, fine to medium SAND; moist to wet;
locally organic, scattered organics and
vivianite crystals; (Qpnl) ML/SM/OL.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-3
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
trace of fine sand; moist; interbedded with
layers of peat and silty, fine sand, scattered
organics, scattered oxidation, only trace of
clay below 7.5 feet; (Qpnl) ML/SM.
Very dense, brown, slightly silty to silty, fine
to medium SAND; moist; locally trace of
gravel; (Qpnf) SP-SM/SM.
organics; (Qpnl) CL.
moist; abundant dark gray, fine sand
partings, abundant organics, scattered
Very dense, gray, silty, fine SAND; moist;
scattered to abundant organics, scattered
pumice fragments; (Qpnf) SM.
silty CLAY; moist; scattered organics and
vivianite crystals; (Qpnl) ML/CL.
slightly silty to silty, fine to medium SAND;
moist; (Qpnf) SP-SM/SM.
gravel; moist; locally slightly clayey (Qpnf)
SM.
77
79/12"
83/12"
76
50/4"
83/11"
67
89
50/5"
80
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
0
0
SAND, trace of silt, trace of fine gravel;
moist; (Qpnf) SP.
organic SILT; moist; (Qpnl) OL.
Hard, dark brown PEAT; moist; (Qpnl) PT.
Very dense, gray, silty, fine to medium
SAND; moist; brown silt layers, abundant
white pumice fragments; (Qpnf) SM.
Hard, gray, slightly fine sandy, slightly
clayey SILT; moist; abundant seams and
interbeds of silty fine sand, locally only
trace of sand, locally only trace of clay,
locally interbedded with layers of silty, fine
sand; (Qpnl) ML/SM.
grading to slightly silty to silty, fine to
medium SAND; moist; abundant silt seams
at top, only trace of silt at bottom; (Qpnf)
SM/SP-SM.
sandy SILT interbedded with very dense,
50/5"
74
70
50/5.5"
94/10"
82
50/5.5"
85/10"
76
50/5.5"
50/5"
50/5"
16
17
18
19
20
21
22
23
24
25
26
27
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
0
0
moist; locally laminated, locally chaotic
texture, scattered organics in silt layers;
(Qpnl) ML/SM.
fine to medium SAND interbedded with
hard, gray, fine sandy, clayey SILT; moist;
locally chaotic texture with clayey rip-up
clasts; (Qpnf) SP-SM/SM/ML.
moist; laminated, abundant fine sand
partings; (Qpnl) CL/CH.
organic-rich seams; (Qpnf) SM/ML/CL.
moist; laminated, interbed of moist to wet,
slightly clayey, fine sandy silt; (Qpnl)
CL/ML.
interbedded with hard, gray, silty CLAY or
clayey SILT, trace of fine sand; moist;
abundant organics in clay and silt beds;
(Qpnf) SM/ML/CL.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
light gray silt partings, scattered
slickensides, locally diced/blocky texture;
feet.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Bentonite Chips/Pellets
FIG. A-4
Bentonite Grout
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
CONCRETE.
GW.
disturbed appearance, brick debris; (Fill)
ML.
moist; layers of very soft, wet, clayey silt,
numerous cobbles at 4 to 8 feet, locally
only trace of silt; (Fill) SP-SM/SP.
Very loose to loose, brown-gray, slightly
silty SAND; moist; wet below 20 feet,
scattered clayey silt clasts and gravel,
locally only trace of silt; (Fill) SP-SM/SP.
CONCRETE.
fine organics, locally laminated, locally only
trace of clay; (Qpnl) ML/SM.
Very dense light brown, clean, fine SAND;
moist; massive; (Qpnf) SP.
depth of 23.5 feet. Drillers were able
to penetrate concrete using an
8-inch auger bit. Drillers noted that
the borehole may have intersected
the edge of a concrete pad, which
made drilling easier than anticipated.
(WOH)
65
82
91/11"
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
SP-SM/GP-GM.
brown, slightly gravelly to gravelly, silty, fine
to medium SAND; moist; wet below 28.5
feet, voids, wood debris, and very loose
material between 26 and 36 feet; (Fill) SM.
Hard, gray to dark brown, slightly clayey
SILT; moist; locally laminated, scattered
compressed peat layers; (Qpnl) ML.
Very dense, light brown, fine SAND, trace
of silt; wet; massive; (Qpnf) SP.
Hard, gray to dark brown, slightly clayey to
clayey SILT; moist; scattered compressed
peat layers and fine organics; (Qpnl) ML.
(WOH)
74
50/5"
52/6"
88
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 2
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
made during vacuum excavation.
Ground Water Level ATD
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 2
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
Plastic Limit
scattered roots; (Fill) SP-SM/SW-SM.
SILT; moist; scattered iron-oxide-stained
sand seams; (Fill) CL/ML.
silty, sandy GRAVEL; moist to wet; (Fill)
GM.
sand seams, scattered iron-oxide stains;
(Fill) CL.
SAND to silty, sandy GRAVEL; moist;
locally clayey; (Qpgm) SM/GM.
seams; (Qpgm) ML.
GRAVEL; moist; massive, locally slightly
clayey to clayey; (Qpgm) GM.
Very dense, gray, silty, gravelly SAND,
trace of clay; wet; massive, locally slightly
50/5"
52/6"
81
50/4"
50/4"
50/5"
50/4"
1
2
3
4
5
6
7
8
9
10
11
12
13
14
E
0.2
5.0
12.0
15.0
20.0
32.0
38.0
57.0
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
0
gravel; moist; (Qpgm/Qpgl) ML.
Very dense, gray-green-brown, slightly
GRAVEL; moist; (Qpgm) SM/GM.
silty to silty, fine to medium SAND; moist to
wet; massive; (Qpnf) SP-SM/SM.
massive; (Qpnl) ML.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
made during vacuum excavation.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 3 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
massive; (Fill) CL.
gravelly, sandy SILT to sandy SAND, trace
of clay; moist; compacted, slightly clayey to
clayey above 16.5 feet; (Qpgm) ML/SM.
Very dense, brown to light brown, slightly
silty to silty, fine to medium SAND; moist;
locally only trace of silt; (Qpnf)
SM/SP-SM/SP.
GRAVEL; wet; (Qpnf) GP-GM.
clayey SILT; moist; interbedded with layers
of peat and organic silt; (Qpnl) ML/OL/PT.
Very dense, brown to light brown, slightly
silty to silty SAND; moist; massive; (Qpnf)
SM/SP-SM.
74
65
87/11"
50/5"
50/6"
78
61
52/6"
50/6"
1
2
3
4
5
6
7
8
9
10
11
12
13
E
0.2
0.5
14.0
19.0
33.0
37.0
49.0
57.0
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 1 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
0
0
0
0
0
0
0
0
0
Very dense, silty, fine SAND grading to
slightly clayey SILT; moist; scattered
iron-oxide stains, slightly gravelly above
70.5 feet; (Qpnf) SM/ML.
SAND, trace of silt; moist to wet; (Qpnf) SP.
Very dense, brown and gray, silty, fine to
medium SAND; moist; locally slightly fine
gravelly, interbedded with layers of peat at
110 feet; (Qpnf) SM/PT.
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 2 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines
p m
Total Depth:
Top Elevation:
Vert. Datum:
Horiz. Datum:
Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The
stratification lines represent the approximate boundaries between material types, and the transition may be gradual.
August 2008 21-1-20885-003
Sheet 3 of 3
Hole Diam.:
Rod Diam.:
Hammer Type:
NOTES
1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.
2. The stratification lines represent the approximate boundaries between soil types, and the transition may be gradual.
3. The discussion in the text of this report is necessary for a proper understanding of the nature of the subsurface materials.
4. Groundwater level, if indicated above, is for the date specified and may vary.
5. USCS designation is based on visual-manual classification and selected lab testing.
M A
S T
E R
(blows/foot)
% Fines