town of linden
TRANSCRIPT
TOWN OF LINDENEAST MAIN STREET MULTIMODAL SIDEWALK PROJECT
PROPOSED 60’ PEDESTRIAN BRIDGEGEOTECHNICAL REPORT
HIGHWAY 13LINDEN, TENNESSEE
Construction Materials Laboratory, Inc.41 Heritage Square
Jackson, Tennessee 38305
Job No. 041902April 2019
Construction Materials Laboratory 2
1. INTRODUCTION
1.1 Project Overview
This report prepared by Construction Materials Laboratory (CML) of Jackson, Tennessee, details the
informal subsurface investigation for the proposed 60’ pedestrian bridge on the east side of Highway 13 in
Linden, Tennessee. This report contains a description of the site conditions and foundation recommendations
based on exploratory test pits.
Based on current information, the proposed construction consists of a 60’ long bridge across an
unnamed tributary of the Buffalo River between the Fred’s store and the Shell gas station. Although the
loading is unknown, a conservative range of 50-60 kips has been assumed on each abutment.
2. SITE CHARACTERISTICS
2.1 Summary Subsurface Investigation
The subsurface investigation was conducted by performing exploratory test pits with a mini excavator
under the direction of Construction Materials Lab. The in-situ conditions were tested at specific depth
intervals by field probing and Pocket Penetrometer (PPR). Based on the scope of the planned construction and
the accessible portions of the site due to underground and overhead utilities; 1 test pit was located on each side
of the bridge near the proposed footings. Test pits were taken to a depth of 6-7 feet. Detailed logs for each
test pit are found in Appendix A and the location of each pit is shown on the attached Location Map.
3. SUBSOIL INVESTIGATION RESULTS
3.1 Laboratory Testing Results
Samples taken from the test pits were sealed and returned to the lab for analysis. In addition to visual
classifications, each soil sample was tested for moisture content and certain samples were further analyzed for
Atterberg limits, grain size analysis and classification according to the Unified Soils Classification System
(USCS). The Atterberg limits consist of the liquid and plastic limits of the soil and are index tests that help to
further characterize the nature of the soil. All laboratory test results are found in Appendix A.
Construction Materials Laboratory 3
3.2 Soil Profile - North End
Test Pit #2 was located on the north side of the bridge and contained a top layer of topsoil, followed
by a stiff layer of sandy, gravelly clay with some large rock from a depth of 1-3 feet. From 3-5 feet, the soil
profile was a brown and gray, slightly firm and wet gravely lean clay with sand (CL). The in-place moisture
at the footing depth was28-30%, and field probing was 4-8 inches. Around 6 feet the soil transitioned to a
layer of firm, wet brown and yellow sandy clay with probing of 2-4 inches, but no large rock.
South End
Test Pit #1 was located on the south side of the bridge, inside the existing guard rail, with a layer of
gravel and rip-rap at the surface. From the surface down to about 4 feet, the profile consists of a mixture of
wet chert gravel with large pieces of concrete and asphalt debris. At 4.5 feet the profile is a mixture of rock
and stiff clayey chert gravel with probing of 2-6 inches and an in-place moisture of 27%. At a depth of 6 feet,
a layer of hard black shale rock and dense chert gravel was encountered.
4. SITE FEASIBILITY
4.1 Foundation Analysis from Subsoil Conditions
Based on the subsoil profile and the proposed construction, the new pedestrian bridges can be
supported by large shallow pier footings. However, during excavation, large rocks, asphalt debris and lenses
of wet clay will likely be encountered, particularly on the south side, where we understand a significant amount
of fill was placed. Preliminary information from the structural engineer indicates pier footings will have an
embedment depth of about 4.5 feet. Table 1 presents specific design recommendations and characteristics for
each side of the bridge. We recommend a layer of limestone base below the footing to help stabilize the base
and cushion the foundation for any large rocks or pieces of debris.
5. FOUNDATION TREATMENT
5.1 Shallow Foundation Design
Table 1 presents the foundation design recommendations for the new bridge. In this case bearing
pressure is defined as the vertical bearing load divided by the footing area. The final embedment will be around
4.5 feet. Regardless of the bearing capacity, isolated footings should be at least 3 feet wide for stability. The
bearing pressure can be increased by 1/3 for temporary transient loading. Prior to placement of the reinforcing
Construction Materials Laboratory 4
steel or concrete, we recommend the installation of an 18-inch layer of compacted Limestone Base to serve as
a stiff working layer, help reduce settlement, and act as a cushion against any large rocks below the footing.
Since these footings are near the creek slope, there should be a minimum of 5 lateral feet of soil between the
closest edge of the footing and the face of the bank to ensure stability and protection against erosion.
If the recommendations and procedures concerning site preparation, fill placement, bearing capacity
and quality control are adhered to, a total settlement of 1 inch and a differential settlement of less than 1/2 inch
are anticipated for the shallow footings.
Values in Table 1 can also be used for design of the north retaining wall.
Table 1. Shallow Foundation Design
Condition NORTH SOUTH
Total Soil Unit Weight (lb/ft3) 125 125
Active Earth Pressure (KA) 0.33 0.33
Passive Earth Pressure ( KP)1 3.50 3.50
Base Sliding Friction (μ)2 0.44 0.44
At Rest Earth Pressure (KO) 0.60 0.60
Allowable Bearing Pressure (psf) 2,200 2,200
Soil Characteristics at Ftg. Depth Wet, Firm Lean Gravelly Clay Firm Silty Gravelly Sand
Potential Undercut / Remarks
Recommend an additional 18 inch
undercut below the footing, and
installation of an 18-inch-thick
layer of Limestone Base (Type A,
Grading D) compacted in 2 lifts to
at least 97% compaction.
Will encounter large rock and
asphalt debris during excavation.
Recommend an additional 18 inch
undercut below the footing, and
installation of an 18-inch-thick
layer of Limestone Base (Type A,
Grading D) compacted in 2 lifts to
at least 97% compaction.
Notes:1. A reduction factor of 2 applied to passive pressure is recommended due to the large movement required tomobilize the passive resistance, particularly in clayey soils at these sites.2. The base sliding factor should apply only to the dead load. This is an allowable sliding factor and already has ainterface reduction factor and an overall safety factor of 1.5 applied and assumes the installation of limestone basebelow the footing.
Construction Materials Laboratory 5
6. INSPECTION AND CONTINGENCIES
6.1 Inspection and Quality Control
All modifications to the site should be monitored and inspected by a competent technician. This
includes excavations, undercutting, fill operations, and foundation preparation. Prior to fill placement;
proposed on-site or haul in fill material should be evaluated for suitable attributes, and ASTM D-698 moisture
density tests (Proctor tests) should be performed on every type of fill used on site. Moisture density tests of
compacted fill should be checked at a minimum of 1 test per 1,000 square feet for each layer of compacted fill
and at least 1 test for every lift of limestone base in the footings.
6.2 Contingencies and Limitations
All recommendations contained in this report are based on the interpretation of the limited test pit
investigation and current knowledge of the area. Although test pits were conducted at relevant locations
according to the proposed construction, it should be noted that the information obtained depicts the subsurface
conditions at the specific locations at the particular time of the investigation. Although only minor deviations
are expected, soil conditions could differ between locations as well as outside the area of the investigation.
Any significant deviations found during construction should be reported to this office in order to modify the
geotechnical report and subsequent recommendations.
The scope of this report does not contain any environmental investigation or assessment of the site or
any adjacent areas. This report does not address the corrosive potential or otherwise hazardous nature of any
soil found in the exploration. Any statements contained in this report concerning the location or conditions of
organic material are purely an assessment of the subsurface soil profile towards the evaluation of foundation
treatment.
Any changes or revisions to the final plans including loading conditions or locations of structures
should be reported to this office in order to modify this report and the subsequent recommendations.
US-57 ALIGNMENT
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END PROJECT
STA:20+21.12
N:473662.7730
E:1423816.0510
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HIGHWAY 412 (E MAIN ST) - 18+62.40
HIGHWAY 13 - 0+00.00
N:473611.2732
E:423665.9358
LIMITS OF CONSTRUCTION
4+48.29
N:474051.7287
E:142358.4962
PAPER LOCATED CENTERLINE
EXISTING R.O.W.
EXISTING R.O.W.
UN-NAMED TRIBUTARY
TO THE BUFFALO RIVER.
STA:17+00.90
OFFSET:15.02L
STA:16+66.69
OFFSET:14.99L
STA:16+60.70
OFFSET:14.87L
STA:15+82.67
OFFSET:14.61L
STA:15+45.93
OFFSET:24.24L
STA:18+00.06
OFFSET:50.95L
STA:18+14.80
OFFSET:66.24L
STA:18+18.88
OFFSET:39.78L
STA:18+26.39
OFFSET:32.87L
STA:18+37.03
OFFSET:30.51L
STA:18+87.45
OFFSET:20.62L
STA:18+93.41
OFFSET:19.49L
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STA:19+38.83
OFFSET:37.59L
STA:19+20.77
OFFSET:57.21L
STA:19+42.15
OFFSET:40.71L
STA:0+62.28
OFFSET:59.56L
STA:0+68.79
OFFSET:68.62L
2
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STA:17+97.39
OFFSET:49.62L
STA:18+04.68
OFFSET:54.82L
STA:18+08.16
OFFSET:58.41L
STA:19+10.96
OFFSET:34.20L
STA:19+27.40
OFFSET:48.42L
STA:19+24.18
OFFSET:52.24L
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473611.2732
1423665.9358
473466.9942
1423360.8215
473506.1773
1423420.9566
473531.1987
1423465.5270
473555.0960
1423514.0790
473565.6800
1423538.0840
473582.9320
1423581.8280
473608.4760
1423657.1820
473621.7090
1423698.5940
473627.9070
1423717.4240
473635.5450
1423740.1370
473640.9020
1423755.9220
473648.9330
1423778.1320
STA:17+00.70
OFFSET:30.26L
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PROPOSED CURB
RAMP W/ DETECTABLE
WARNINGS. SEE TDOT
STD DWG RP-H-5.
PROPOSED CURB RAMP W/O
DETECTABLE WARNINGS. SEE
TDOT STD DWG RP-H-7.
PROPOSED CURB RAMP W/O
DETECTABLE WARNINGS. SEE
TDOT STD DWG RP-H-7.
PROPOSED CURB
RAMP W/ DETECTABLE
WARNINGS. SEE TDOT
STD DWG RP-H-5.
PROPOSED 6-30 CURB AND
GUTTER. SEE TDOT STD
DWG RP-VC-10.
PROPOSED DRIVE
APRON. SEE TDOT
STD DWG RP-D-16.
PROPOSED DRIVE SEE
SHEET 2A FOR DETAIL.
PROPOSED
PEDESTRIAN REFUGE.
SEE TDOT STD DWG
RP-H-6. (2 PLCS)
PROPOSED 60'
PEDESTRIAN BRIDGE.
PROPOSED DRIVE
APRON. SEE TDOT STD
DWG RP-D-16.
PROPOSED 5' WIDE SIDEWALK.
MAX CROSS SLOPE 1.5%
SEE TDOT STD DWG RP-S-7.
PROPOSED CURB RAMP
W/O DETECTABLE
WARNINGS. SEE TDOT
STD DWG RP-H-7.
PROPOSED CURB RAMP W/O
DETECTABLE WARNINGS. SEE
TDOT STD DWG RP-H-10.
PROPOSED 5' WIDE SIDEWALK.
MAX CROSS SLOPE 1.5%
SEE TDOT STD DWG RP-S-7.
EXISTING EDGE OF
ASPHALT
PROPOSED CURB RAMP W/O
DETECTABLE WARNINGS. SEE
TDOT STD DWG RP-H-7.
PROPOSED CURB RAMP W/O
DETECTABLE WARNINGS. SEE
TDOT STD DWG RP-H-7.
PROPOSED DRIVE
APRON. SEE TDOT
STD DWG RP-D-16.
STA:15+29.65
OFFSET:15.29L
EXISTING
EDGE OF
ASPHALT
HWY 13
STA:1+74.56
OFFSET:24.51R
HWY 13
STA:1+44.38
OFFSET:24.17R
HWY 13
STA:1+92.98
OFFSET:24.72R
HWY 13
STA:3+05.02
OFFSET:26.92R
HWY 13
STA:3+03.00
OFFSET:38.55R
HWY 13
STA:3+67.98
OFFSET:36.77R
HWY 13
STA:4+37.83
OFFSET:36.20R
HWY 13
STA:1+69.51
OFFSET:29.95R
HWY 13
STA:1+97.96
OFFSET:30.28R
HWY 13
STA:2+96.42
OFFSET:44.65R
END OF SIDEWALK
CONSTRUCTION
HWY 13
STA:4+45.42
OFFSET:36.20R
HWY 13
STA:2+98.62
OFFSET:31.27R
LIMITS OF
CONSTRUCTION
0+25.04
LIMITS OF
CONSTRUCTION
0+26.21
BEGIN
RETAINING
WALL
STA:3+68.11
OFFSET:42.27R.
PROPOSED 8" RETAINING WALL.
SEE DETAIL SHEET 2C.
END
RETAINING
WALL
STA:3+80.11
OFFSET:42.25R
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REVISIONS
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TYPE YEARPROJECT NO.
SHEET
NO.
R.O.W. 2018 68LPLM-S2-020
COORDINATES ARE NAD/83(1995),
ARE DATUM ADJUSTED BY THE
FACTOR OF 1.00005 AND TIED TO
THE TGRN. ALL ELEVATIONS ARE
REFERENCED TO THE NAVD 1988.
SIDE
WA
LK P
ROJE
CT
2018 68LPLM-S2-020
CONST. 2019 68LPLM-S3-020
6A
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20'
80'10'
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