Exhibit A-3_Subsurface Exploration Services-Oct 7 2010

Tai and Associates, PLLC
5561 McNeely Drive, Suite 101 Raleigh, NC 27612 [phone] [phone] (Fax)
October 7, 2010
Mr. Brian J. Natwick
Crescent Resources, LLC
400 South Tryon Street
Charlotte, North Carolina 28285
Re:Subsurface Exploration Services
Erwin Square -Residential
Durham, North Carolina
Tai Job No.: 10-165-1
Dear Mr. Natwick:
In accordance with your authorization, we have completed a subsurface exploration program for
the referenced project. This program consisted of the drilling of thirteen (13) soil borings, classification of
soil samples recovered, engineering services including analyses of subsurface conditions, consultation, and
the preparation of this written report. The work was performed in general conformance with our
September 13, 2010 proposal.
FIELD EXPLORATION
The field exploration program consisted of the drilling of thirteen (13) soil borings (B-1 thru B-12,
and B-11A) to a maximum depth of 40.0 feet below the existing ground surface. The drilling was
performed with a CME 550 ATV drill rig equipped with 2-1/4” inside diameter hollow stem augers to
advance the boreholes. Standard Penetration Tests (ASTM D-1586) were performed in all borings at every
2.5-foot interval to 10.0 feet deep followed by one at every 5.0 foot interval.
The approximate locations and logs of the thirteen (13) borings are shown on the attached “Boring
Location Plan” and “Boring Logs”. The boring locations were staked by measuring from existing ground
features and should be considered approximate. The boring elevations are interpolated from 2.0 and 10.0
foot contour lines shown on the Durham County GIS website and should be considered approximate.
LABORATORY TESTING
The laboratory-testing program consisted of the visual classification of all soil samples recovered
(ASTM D-2488). The descriptions of the subsurface materials as represented by the soil samples
recovered are indicated on the “Boring Logs.” All samples obtained will be discarded in 60 days unless
otherwise instructed.
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 2
SUBSURFACE CONDITIONS
Based on the results of the field exploration program, the subsurface material of the project site
can be described as consisting of the following units of soil:
1.Surface Materials (Topsoil): The surface material in all the borings consists of 1.0 to 3.0
inches of topsoil containing sandy-silty organic soil and/or mulch. Root mat may extend to a
deeper depth.
2.Fill Soil:Existing fill or backfill soils are found in eleven (11) borings. Borings B-11 and B-
11A did not encounter any fill. The deepest fill was encountered in borings B-3 and B-4 at
depths of 16.0 and 18.3 feet below the ground surface, respectively. The fill depth in the
remaining borings varies between 5.5 feet and 12.0 feet deep. It consists of fine sandy clay
and silt with gravel. Deeper fill or backfill soil may exist elsewhere on site not drilled. We
assume that the existing fill was placed in multiple phases for the construction of utility lines
and structures. The upper 8.0 to 12.0 feet of this unit of soil is of moderate engineering
quality. The deep fill encountered in B-3 and B-4 is of poor engineering quality and not
suitable to support the proposed structures.
3.Silty-Clayey Soil: Below the fill soil is the natural residual soil and it was encountered in all
thirteen (13) borings. It contains sandy-silty, or sandy-clayey, natural residual soils derived
from the in-place weathering of the parent Triassic rocks. This moderate engineering quality,
stiff to hard material varies in thickness from 11.0 to 23.0 feet. Boring B-12 contained a 2.5
foot thick layer of firm, clay of medium to high plasticity.
4.Diabase Dikes and Sills: Diabase dikes and sills are intrusive geologic formations. This very
poor engineering quality material consists of wet plastic silts, wet silty sands, gravels, and
boulders of varying sizes. Evidence of diabase was encountered in boring B-11.
As depicted on the boring location plan, this geologic anomaly is often found in a 5-foot. to
25-foot wide dike running slightly east of north.
5.Weathered Rock: The next unit of soil at the project site is the Weathered Triassic siltstone or
sandstone which occurs below the above soil overburden. As indicated in the “Boring Logs,”
the depth of this very hard material occurs at depths varying from 18.3 feet to 34.5 feet below
the existing ground surface.
The Triassic rock found at the site consists of a random mixture of slightly lighter colored
sandstone and darker colored siltstone. This is evident by the samples collected in the
weathered rock mass and also the residual soil layer above. This unit is of good engineering
quality.
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 3
6.Partially Weathered Rock/Boulders: Some of the weathered rock becomes much harder with
depth and is classified as partially weathered rock (PWR) or boulders. For this project, the
partially weathered rock is defined as very hard, rock-like material having an N value of 50
blows over one inch or less. PWR was encountered in borings B-3 and B-7 at an elevation of
381.0 and 388.0, respectively. The difference between weathered rock and partially weathered
rock can be very small and may vary erratically in depths from place to place.
7.Groundwater: Trapped or perched groundwater was encountered all thirteen (13) boreholes.
The groundwater encountered exists in the fill above the silty-clayey residual soil. Additional
trapped or perched water may exist elsewhere on site not drilled. Surface water control
measures will be required throughout the site during construction.
The subsurface materials encountered in the thirteen (13) borings are presented in three (3)
“Subsurface Cross Sections” and a “Summary of Subsurface Materials” attached to this report.
PROPOSED PROJECT
We understand that the proposed project will involve the design/construction of a four-story
residential structure and three-story parking deck. The residential structure will consist of one cast-in-
place story and three wood framed stories above. Cut and fill depths are assumed to be 3.0 to 5.0 across
the site. The proposed finish floor elevation, foundation plan, and grading plan is not available for review
at the time of this report. We assume the finish floor elevation will be about 410.0.
RECOMMENDATIONS
Apartment Building
We recommend that the columns and load bearing walls of the proposed Erwin Square Residential
Apartment Building should be supported on single, combined, or continuous footings designed for a 3,000
psf bearing capacity. Subgrade improvement consisting of VibroPiers will be required.
Parking Deck
We recommend that the columns and load bearing walls of the proposed Erwin Square Residential
Parking Deck should be supported on single, combined, or continuous footings on an improved subgrade
and designed for the bearing capacity shown below.
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 4
Subgrade Improvement-Parking Deck
1.Localized Undercut and Replacement
We recommend the shallow foundations for the parking deck be undercut and supported
on an ABC stone mat layered with geotextiles. A layer of separation geofabric (Mirafi HP370)
should be installed prior to ABC stone placement. The geofabric should be placed in the
excavation with 2.0 feet of overlap and 2.0 of wrap-up at the edges. Two (2) layers of stabilization
geogrid (Tensar Triax TX5) should be installed after the first and second lift of ABC stone with
2.0 feet overlap and 2.0 feet of wrap-up at the edges. The ABC stone should be compacted to 98%
of the NC DOT modified proctor. See “Subgrade Improvement Section” attached to this report for
additional details. The design bearing capacity of this option is 8,000 psf.
2.VibroPiers
We recommend the VibroPiers extend to residual soil. The VibroPier size and locations
should be determined on a design-build basis by a registered professional engineer. We
recommend consulting with Mr. Todd Ross, PE, Hayward Baker, Inc., 336-668-0884. Our firm
should review the VibroPier submittal with design calculations, pier locations, depths and
specifications. The design bearing capacity for this option is 6,000 psf.
The VibroPier design and construction must take into account fill soils, groundwater, and possible
soft diabase soils. It appears that pre-drilling will be required to advance the piers through the fill and a
bottom-feed VibroPier system will be required.
All footing excavations must be inspected for the design bearing capacity. The maximum total and
differential post-construction settlement will be about 1.0 inches and 0.5 inches, respectively. Expansion
joints should be provided on the exterior walls at regular intervals and at every building break. There
should be at least 12 inches of cover on all exterior footings to prevent frost penetration. Footings should
be designed at an elevation that no utility lines, utility line excavation, and any other footings are located
within the 1:1 zone of influence of the subject footing edge.
Seismic Site Classification
The project site belongs to seismic Site Class D, according to the 2009 International Building
Code.
Groundwater
During construction, the groundwater will not cause major construction problems but trapped
water within the existing fill will enter deep excavations during construction. We expect that, at least in
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 5
some areas, surface and groundwater control measures, such as trenching, ditching, sumps, pumps, French
drains, etc., will be required.
Excavation
All normal size earth-moving equipment can easily move the materials above the weathered rock
layer. Normally, slow excavation with a large hydraulic excavator such as CAT 330, or equal, should be
able to excavate the hard soil and most of the weathered rock layer.Rock should be defined as material
that cannot be excavated with a track mounted hydraulic excavator, equipped with rock teeth, equivalent to
a CAT 330. Boulders exceeding 1.0 cy in mass excavations and 0.75 cy in trench excavations should also
be classified as rock. Definition and unit prices for rock and trench excavation should be included in the
specification and contract. Rock excavation in utility trenches and footings may be required near boring
B-11 and possibly elsewhere between the borings.
Fill and Backfill
All fill and any backfill should be placed and compacted to a minimum of 98% of the Standard
Proctor Density (ASTM D-698). The moisture content of the fill during placement must be kept within 3%
of the optimum value. Most of the dry fill, natural soil, hard soil, and weathered rock in the cut areas
should provide suitable regular backfill material except for any plastic clay pockets and all boulders larger
than 6.0 inches in any dimension. In-place density tests should be performed at a rate of one test per 2,500
sf, per lift, per day (ASTM D-1556). The final slope of cut and fill should be 2H:1V starting at least 5.0
feet from the edge of all footings and paved areas.
Utilities
All utility pipes should be supported on top of at least 6.0 inches of suitable granular soil or #57
washed stone. The backfill should consist of clean natural soil, or suitable fill, and should be compacted to
98% of the Standard Proctor Density (ASTM D-698). Removal of weathered rock or isolated boulders by
a large track backhoe equipped with rock teeth will be required in any deep utility trenches.
Pavement
The pavement system should be supported on a carefully prepared site subgrade as outlined in the
next section. Based on the AASHTO Method, 20-year life, and assumed soaked CBR Value of 6.0, the
heavy-duty pavement should consist of 4.0 inches of asphalt over 10.0 inches of ABC stone. Regular
parking areas should be paved with 2.0 inches of asphalt over 7.0 inches of ABC stone. A layer of
geofabric such as Mirafi 500X may be required.
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 6
Slabs
The floor slab area should be constructed over 4.0 inches of compacted ABC stone over a well
prepared compacted subgrade. Any plastic clay soil or existing fill soil encountered in the subgrade should
be undercut at least 2.0 feet and replaced with suitable soil compacted to 98% of the Standard Proctor
Density. Expansion joints should be provided as required by ACI to minimize uncontrolled shrinkage
cracks. The fine, silty, clayey soil will be disturbed after grading by the construction activities. Any
damaged subgrade must be repaired prior to the placement of stone and concrete. The modulus of
subgrade reaction for slabs and concrete pavements is 300 kips per cubic foot.
CONSTRUCTION CONSIDERATIONS
Engineering Behavior of Soils
The on-site silty soils are sensitive to surface water damage. Grading operations performed in the
wet winter months of November through March will be difficult, time consuming, and expensive.
Grading
The project site should be cleared of all the existing surface features such as topsoil, debris, etc.
Most of the non-plastic fill and natural, residual soil can be reused as structural fill.
Surface water control measures must be placed prior to any grading and earthwork activity. The
cleared site will not promote surface water drainage. We anticipate that very little surface water will
percolate into the fine silty-clayey soil. As a result, the construction team should plan for all surface water
being directed trenches and stormwater ponds.
The cleared site where fill is required should be carefully proofrolled and inspected to identify any
soft soil, plastic clay, or other unsuitable soil that requires undercutting and backfilling with suitable soil
and/or placement of geofabric (Mirafi 500X or equal).
Backfill should consist of clean, existing fill, sandy-silty, residual soil, or approved off-site
borrow, placed in 8.0-inch layers and compacted to 98% of the required Standard Proctor Density (ASTM
D-698). The moisture content should be maintained to within 3% of the optimum. In -Place Density tests
should be performed on the fill and backfill at a rate of one test per 2,500 sf, per lift, per day (ASTM D-
1556).
We recommend removing the soft, loose existing backfill above the utility line near borings B-1
and B-4 and replacing with suitable well-compacted backfill. Where located below foundations, the utility
should be removed or grouted solid and abandoned in-place
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 7
Shallow Foundations
The building pad should be rough graded prior to Vibro Pier Installation. Footings not poured on
the same day of excavation should be protected with a 2-inch thick concrete mud-mat to protect from
surface water damage. All footing subgrades must be compacted with a rammax or jumping jack and
inspected by a representative of this firm utilizing field engineering judgment.
VibroPiers
The VibroPier design should be submitted for review to the structural engineer and to our firm.
The pier installation should take place after mass grading and after the building pad is on rough grade.
Clean, dry, non plastic soil excavated during pre-drilling may be suitable for re-use as structural fill.
VibroPier installation will be time consuming and difficult where diabase is encountered due to boulders.
Boulders or obstructions encountered within the top 10.0 should be excavated using normal earth moving
equipment. Once the excavation is properly backfilled, VibroPier installation can resume.
Slab Subgrades
The subgrade for the concrete slab system will require inspection of the subgrade and ABC stone
subbase using field engineering judgment. Some additional improvement may be required including
undercutting and/or placement of Mirafi 500X geofabric due to damage by surface water and construction
traffic.
ADDITIONAL SERVICES
Based on our experience working on projects similar to Erwin Square Residential, revisions and
modifications may be necessary as the design progresses. The foundation and earthwork design
recommendations presented in this report are based not only on our field and laboratory test results, but
also on the very limited preliminary project information currently available to us.
When grading and foundation plans become available, we would be pleased to have the
opportunity to review the plans to check for compatibility with the geotechnical recommendations.
We believe that the vibro piers may be able to be omitted in the residential section. Instead,
additional undercut would be required. For this option to be explored, we recommend additional
exploration by Test Pits in the general area of borings B-3 and B-4.
FIELD SERVICES
All earthwork, foundation, slab, and utility construction activities should be observed by one of
our experienced geotechnicians. He will offer assistance in determining the depth of any unsuitable
subgrade soil, the foundation bearing capacity, the adequacy of compaction, the areas that require
Mr. Brian J. Natwick
Re: Tai Job No.: 10-165-1
October 7,2010
Page 8
geofabric, the definition of rock or trench rock, and any other site-related problems. We cannot be held
responsible for any construction problems or the performance of the foundation unless we are authorized
to provide these field services.
CLOSURE
It has been a pleasure to work with you on the pre-design phase of this project. If you have any
questions, or if you would like to discuss the issue further, please feel free to call at your convenience.
Very Truly Yours,
Tai and Associates, PLLC
Firm License No.: P-0370
Allan Paul, EI
Matthew T. Ryan, PE
Attachments:
1.Boring Location Plan (1)
2.Boring Logs (13)
3.Subsurface Cross Sections (3)
4.Summary of Subsurface Materials
5.Subgrade Improvement Section
BORING LOCATION PLAN WITH ELEVATION OF RESIDUAL SOIL
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
TAI JOB NO.: 10-165-1 SEPTEMBER 2010
B-1
(388.0)
B-11/11A
B-12
B-10
B-2
B-3
B-4
B-5
B-6
B-7
B-8
B-9
(397.5)
(386.7)
(399.5)(406.5)
(402.5)
(402.0)(407.5)
(405.5)
(408.5)(414.0)
(394.0)
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
19
8
11
8
9
33
0.4
13.1
0.1
2.5
5.5
8.0
12.0
16.0
23.5
30.0
TOPSOIL
FILL - Brown, very stiff, sandy SILT
FILL - Tan, Brown, firm, sandy SILT
FILL - Brown, stiff, sandy SILT with asphalt
FILL - Tan, firm, sandy SILT with gravel
Dark brown, gray, stiff, fine sandy, silty, CLAY
Gray, dark brown, hard, SILT
WEATHERED ROCK - Gray Triassic SANDSTONE
Boring Terminated at 30.0 Feet
10-165-1
B-1
SEPTEMBER 20, 2010
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC
50
0.4
50
400
395
390
385
380
375
370
365
360
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
26
11
13
15
24
48
20
12.0
0.2
3.0
5.5
12.0
16.0
22.0
28.0
35.0
TOPSOIL
FILL - Brown, gray, very stiff, sandy SILT
POSSIBLE FILL - Gray, orange, stiff, silty CLAY
Brown, gray, stiff, silty CLAY
Brown, very stiff, slightly sandy, silty CLAY
Dark brown, hard, silty CLAY
Dark brown, gray, very stiff, silty CLAY
WEATHERED ROCK - Gray Triassic SANDSTONE
Boring Terminated at 35.0 Feet
10-165-1
B-2ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 17, 2010
0.3
50
0.5
50
403
398
393
388
383
378
373
368
363
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
6
5
9
5
1
34
21
10.9
0.1
2.5
5.5
8.0
12.0
16.0
27.0
31.0
TOPSOIL
FILL - Brown, orange, tan, firm, sandy SILT
FILL - Tan, brown, firm, sandy CLAY
FILL - Brown, tan, orange, stiff, sandy SILT
FILL - Brown, orange, gray, moist, firm, sandy CLAY
FILL - Tan, gray, wet, very soft, sandy SILT
Dark brown, gray, hard to very stiff, silty CLAY
WEATHERED ROCK - Brown Triassic SILTSTONE
10-165-1
B-3ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
35.0
Boring Terminated at 35.0 Feet
PARTIALLY WEATHERED ROCK - Gray
Triassic SANDSTONE
0.2
50
0.1
50
410
405
400
395
390
385
380
375
370
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
16
8
16
8
1
18.2
0.1
2.5
5.5
8.0
12.0
18.3
25.0
TOPSOIL
FILL - Tan, brown, very stiff, sandy SILT
FILL - Tan, brown, firm, sandy SILT
FILL - Gray, very stiff, sandy CLAY
FILL - Brown, gray, sandy CLAY with coal
FILL - Gray, moist, very soft, sandy CLAY
WEATHERED ROCK - Gray Triassic SANDSTONE
Boring Terminated at 25.0 Feet
10-165-1
B-4ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
*Petroleum Odor
0.5
50
0.2
50
405
400
395
390
385
380
375
370
365
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
17
7
11
9
16
22
10.2
0.1
2.5
5.5
8.0
16.0
30.0
TOPSOIL
FILL - Gray, brown, black, firm, silty SAND
FILL - Gray, brown, orange, firm, silty CLAY
Gray, brown, stiff, silty CLAY
Brown, stiff to very stiff, silty CLAY
Gray, dark brown, very stiff, fine sandy, silty CLAY
WEATHERED ROCK - Gray Triassic SANDSTONE
Boring Terminated at 30.0 Feet
10-165-1
B-5ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 17, 2010
22.0
0.5
50
0.3
50
405
400
395
390
385
380
375
370
365
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
17
8
11
4
5
27
18
11.2
0.2
3.0
5.5
8.0
12.0
16.0
22.0
28.5
TOPSOIL
FILL - Tan, firm, silty SAND
FILL - Tan, brown, firm, sandy CLAY
Tan, brown, black, firm, silty SAND with slickensides
Light brown, tan, orange, moist, very loose, silty SAND
Tan, gray, moist, loose, silty SAND
Tan, purple, moist, very firm, silty SAND
Tan, brown, yellow, wet, firm, silty SAND
10-165-1
B-6ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
35.0
Boring Terminated at 35.0 Feet
WEATHERED ROCK - Reddish brown, wet,
WEATHERED ROCK - Gray, wet, Triassic SILTSTONE
32.0
Triassic SILTSTONE
0.3
50
0.5
50
with mica
with mica
with mica
with mica
with mica
412
407
402
397
392
387
382
377
372
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
19
10
6
12
16
20.8
0.1
3.0
6.0
8.5
13.0
19.0
23.0
25.0
TOPSOIL
FILL - Brown, gray, silty, firm, clayey, medium to
FILL - Brown, stiff, sandy, silty CLAY
FILL - Brown, tan, firm, plastic CLAY
Gray, stiff, fine sandy, clayey SILT
Gray, brown, very stiff, CLAY
WEATHERED ROCK - Brown Triassic SANDSTONE
PARTIALLY WEATHERED ROCK - Brown
Boring Terminated at 25.0 Feet
10-165-1
B-7ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
coarse SAND
Triassic SANDSTONE
0.2
50
0.1
50
411
406
401
396
391
386
381
376
371
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
41
8
7
12
43
43
7.0
0.1
3.0
5.5
8.0
12.0
20.5
30.0
TOPSOIL
FILL - Gray, dense, silty SAND
FILL - Gray, tan, firm, silty CLAY
FILL - Gray, firm, silty CLAY
Brown, black, stiff, slightly sandy, silty CLAY
Brown, hard, silty CLAY
WEATHERED ROCK - Brown Triassic SILTSTONE
Boring Terminated at 30.0 Feet
10-165-1
B-8ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 17, 2010
0.3
50
0.3
50
410
405
400
395
390
385
380
375
370
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
9
4
7
12
14
28
10.3
0.2
3.0
5.5
8.0
16.0
30.0
TOPSOIL
FILL - Brown, red, gray, stiff, silty CLAY
POSSIBLE FILL - Tan, orange, soft, slightly sandy,
Gray, tan, firm, fine sandy SILT
Tan, firm, silty SAND
Gray, very firm, silty SAND
WEATHERED ROCK - Tan Triassic SANDSTONE
Boring Terminated at 30.0 Feet
10-165-1
B-9ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
21.9
0.3
50
0.5
50
silty CLAY
413
408
403
398
393
388
383
378
373
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
14
7
11
23
23
31
27
48
29.1
0.1
3.0
5.5
16.0
22.0
25.0
36.0
40.0
TOPSOIL
FILL - Brown, stiff, sandy SILT
FILL - Brown, tan, wet, firm, silty CLAY
Dark brown, gray, very stiff, silty CLAY
Gray, dense, silty, fine SAND
Gray, brown, very stiff to hard, silty CLAY
WEATHERED ROCK - Brown Triassic SILTSTONE
WEATHERED ROCK - Gray Triassic SANDSTONE
Boring Terminated at 40.0 Feet
10-165-1
B-10ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
0.3
50
0.550
8.5
FILL - Brown, gray, stiff, silty CLAY
414
409
404
399
394
389
384
379
374
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
11
10
15
12
13.2
0.1
3.0
5.5
13.5
TOPSOIL
Orange, red, brown, stiff, sandy SILT
Red, brown, firm, silty CLAY with slickensides
Brown, moist, stiff, sandy SILT (Diabase Dike)
Auger Refusal at 13.5 Feet
10-165-1
B-11ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 17, 2010
Numerous boulders and cobbles encountered
0.050
414
409
404
399
394
389
384
379
374
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
5
17
13
30
51
12.8
13.5
17.0
22.0
27.0
34.5
40.0
AUGER PROBE TO 13.5'
Dark tan, firm, sandy, silty CLAY
Dark tan, firm, silty SAND
Dark brown, purple, hard, fine sandy, silty CLAY
Tan, wet, hard, slightly sandy SILT
WEATHERED ROCK - Brown, wet, Triassic
Boring Terminated at 40.0 Feet
10-165-1
B-11AERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 17, 2010
OFFSET 10' TOWARD B-12
SILTSTONE
0.350
414
409
404
399
394
389
384
379
374
DEPTH DESCRIPTION GW ELEV 10 50 90
BORING LOG
TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
PROJECT:
LOCATION:
CLIENT:
BORING NO.
PAGE 1 OF 1
DATE: N-VALUE (ASTM D-1586)
27
11
9
8
9
73
19
47
14.2
0.1
3.0
5.5
9.5
12.0
18.5
22.0
27.0
TOPSOIL
FILL - Tan, very stiff, sandy SILT
FILL - Tan, brown, stiff, sandy CLAY
FILL - Orange, tan, gray, stiff, clayey, sandy SILT
Gray, firm, plastic CLAY
Gray, dark brown, stiff, silty CLAY
Gray, moist, very dense, silty SAND
Tan, moist, firm, silty SAND
10-165-1
B-12ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC SEPTEMBER 20, 2010
27.0
Tan, moist, dense, silty SAND
40.0
WEATHERED ROCK - Gray, wet, Triassic
Boring Terminated at 40.0 Feet
SILTSTONE
WEATHERED ROCK - Brown, wet, Triassic
SILTSTONE
35.0
0.550
0.4
50
418
413
408
403
398
393
388
383
378
13.118.2
20.8
12.0
23.5
30.0
18.3
25.0
8.5
19.0
23.0
25.029.1
25.0
40.0
8.5
420
415
410
405
395
400
385
390
380
375
370
B-10
B-7
B-4
B-1
14
7
11
23
23
31
27
48
19
8
11
8
9
33
0.4
0.4
0.5
0.3
19
10
6
12
16
0.2
0.1
16
8
16
8
1
0.2
0.5
FILL
RESIDUAL
WR
PWR
DIABASE
TAI JOB NO. 10-165-1 TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
SUBSURFACE CROSS SECTION - A
PROJECT:
LOCATION:
CLIENT:
PAGE 1 OF 1
DATE:
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC
SEPTEMBER 2010
12.0
10.2
7.0
13.2 12.8
5.5
28.0
35.0
5.5
30.0
8.0
20.5
30.0
5.5
13.5 13.5
34.5
40.0
22.0
420
415
410
405
395
400
385
390
380
375
370
B-11 B-11A B-8
B-5
B-2
11
10
15
12
0.0
5
17
13
30
0.3
51
41
8
7
12
43
43
0.3
0.3
17
7
11
9
16
22
0.3
0.5
26
11
13
15
24
48
20
0.5
0.3
FILL
RESIDUAL
WR
PWR
DIABASE
TAI JOB NO. 10-165-1 TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
SUBSURFACE CROSS SECTION - B
PROJECT:
LOCATION:
CLIENT:
PAGE 1 OF 1
DATE:
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC
SEPTEMBER 2010
10.9
11.2
10.3
14.2
16.0
27.0
31.0
5.5
28.5
5.5
30.0
9.5
35.0
35.0
21.9
30.0
40.0
420
415
410
405
395
400
385
390
380
375
370
B-12
B-9 B-6
B-3
27
11
9
8
9
73
19
47
0.5
0.4
9
4
7
12
14
28
0.5
0.3
17
8
11
4
5
27
18
0.5
0.3
6
5
9
5
1
34
21
0.2
0.1
FILL
RESIDUAL
WR
PWR
DIABASE
TAI JOB NO. 10-165-1 TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
SUBSURFACE CROSS SECTION - C
PROJECT:
LOCATION:
CLIENT:
PAGE 1 OF 1
DATE:
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC
SEPTEMBER 2010
SUMMARY OF SUBSURFACE MATERIALS
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
B-1 30.0 400.0 12.0 388.0 23.5 376.5 13.1 386.9
B-2 35.0 403.0 5.5 397.5 28.0 375.0 12.0 391.0
B-3 35.0 410.0 16.0 394.0 27.0 383.0 10.9 399.1
B-4 25.0 405.0 18.3 386.7 18.3 386.7 18.2 386.8
B-5 30.0 405.0 5.5 399.5 22.0 383.0 10.2 394.8
B-6 35.0 412.0 5.5 406.5 28.5 383.5 11.2 400.8
B-7 25.0 411.0 8.5 402.5 19.0 392.0 20.8 390.2
B-8 30.0 410.0 8.0 402.0 20.5 389.5 7.0 403.0
B-9 30.0 413.0 5.5 407.5 21.9 391.1 10.3 402.7
B-10 40.0 414.0 8.5 405.5 25.0 389.0 29.1 384.9
B-11/B11A 40.0 414.0 414.0 34.5 379.5 12.8 401.2
B-12 40.0 418.0 9.5 408.5 27.0 391.0 14.2 403.8
DEPTH TO
GROUNDWATER
(ft)
GROUNDWATER
ELEVATION (ft)BORING ID BORING
DEPTH (ft)
FILL DEPTH
(ft)
ELEVATION OF
RESIDUAL (ft)
SURFACE
ELEVATION
DEPTH TO
WEATHERED
ROCK (ft)
ELEVATION OF
WEATHERED
ROCK (ft)
TAI JOB NO.: 10-165-1 9/29/2010
GEOFABRIC (MIRAFI HP 370)
GEOGRID (TENSAR TX160)
ABC STONE
95% NC DOT
MODIFIED PROCTOR
ADD WATER EACH LIFT
2.0 FOOT OVERLAP
2.0 FOOT WRAP-UP ON EACH EDGE
2.0 FOOT OVERLAP
2.0 FOOT WRAP-UP ON EACH EDGE
TAI JOB NO. 10-165-1 TAI and ASSOCIATES, PLLC
5561 McNEELY DRIVE, SUITE 101, RALEIGH, NC 27612, 919-782-9525
SUBGRADE IMPROVEMENT SECTION (TYP)
PROJECT:
LOCATION:
CLIENT:
PAGE 1 OF 1
DATE:
ERWIN SQUARE RESIDENTIAL
DURHAM, NORTH CAROLINA
CRESCENT RESOURCES, LLC
SEPTEMBER 2010