SGC Report No. Pardue Mill Road Findings Summary
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Page 1 of 1 2660 White Sulphur Road Gainesville, Georgia 30501 770.536.5220 phone [email protected] Geotechnical Engineering • Special Inspections • CMT • Environmental Services GEOTECHNICAL FINDINGS SUMMARY To: Mr. Jason M. Smith, P.E. From: Mr. Rodney Clark and Mr. Glenn Motes P.E. Date: December 31, 2020 Re: Geotechnical Rock Coring Summary Pardue Mill Road Bridge Repair SGC Project No. 12973G, Report No. 80236 We recently completed geotechnical exploration of the two existing bridge abutments at Pardue Mill that had become damaged following the storm event in October 2020. Plate 1 is a site location plan. As part of the exploration, three soil tests borings were made at the site and included two borings offset about 10 feet from the east abutment (Boring Nos. 2 and 3) and one about 10 feet from the west abutment (Boring No. 1). Plate 2 provides a boring location plan. Initially, the borings penetrated a pavement that ranged from about 5- to 9-inches thick. Below the pavement at each boring location, the borings penetrated about 2½ to 7 feet of existing fill. The fill is generally described as firm to very dense brown and tan reddish brown fine sand to sandy silt. Below the fill partially weathered rock was encountered. The partially weathered rock was encountered only in Boring No. 1. The borings encountered auger refusal at a depth of about 15 feet at Boring No. 1 and about 2½ and 7 feet, respectively, for Boring Nos. 2 and 3. At Boring Location Nos. 1 and 3, rock cores were extracted below the boring refusal depths. The rock cores are generally described as a mixture of biotite gneiss and schist. The competency of the rock is generally good at Boring No. 1; however, at Boring No. 3 the shist at the rock surface appears to contain numerous soil seams the lower the overall competency. Copies of the individual boring logs are attached. Based upon the boring data, it would appear that competent rock for the west abutment can be expected to be around 15 feet. At the east abutment, varied conditions are indicated based upon the boring data. At Boring No. 2, auger refusal was encountered at a depth of 2½ feet below a thin veneer of fill. At Boring No. 3, made about 12 feet away, auger refusal was encountered at a depth of about 7 feet. It is possible that the shallower refusal at Boring No. 2 was the result of rock in the fill. Nevertheless, what the rock cores indicate is the upper rock surface is of lower competency and prone to numerous soil seams. Competent rock at this abutment appears to begin around 25 feet. Any underpinning and/or lateral tie-back system will need to penetrate the competent rock vertically for bearing and laterally for support. Geotechnical Engineering Special Inspections CMT Environmental Services
Transcript of SGC Report No. Pardue Mill Road Findings Summary
Page 1 of 1
2660 White Sulphur Road Gainesville, Georgia 30501 770.536.5220 phone [email protected]
G e o t e c h n i c a l E n g i n e e r i n g • S p e c i a l
I n s p e c t i o n s • C M T • E n v i r o n m e n t a l S e r v i c e s
G EOT ECHNICAL F INDI NG S S UMMARY To: Mr. Jason M. Smith, P.E. From: Mr. Rodney Clark and Mr. Glenn Motes P.E. Date: December 31, 2020 Re: Geotechnical Rock Coring Summary Pardue Mill Road Bridge Repair SGC Project No. 12973G, Report No. 80236 We recently completed geotechnical exploration of the two existing bridge abutments at Pardue Mill that had become damaged following the storm event in October 2020. Plate 1 is a site location plan. As part of the exploration, three soil tests borings were made at the site and included two borings offset about 10 feet from the east abutment (Boring Nos. 2 and 3) and one about 10 feet from the west abutment (Boring No. 1). Plate 2 provides a boring location plan. Initially, the borings penetrated a pavement that ranged from about 5- to 9-inches thick. Below the pavement at each boring location, the borings penetrated about 2½ to 7 feet of existing fill. The fill is generally described as firm to very dense brown and tan reddish brown fine sand to sandy silt. Below the fill partially weathered rock was encountered. The partially weathered rock was encountered only in Boring No. 1. The borings encountered auger refusal at a depth of about 15 feet at Boring No. 1 and about 2½ and 7 feet, respectively, for Boring Nos. 2 and 3. At Boring Location Nos. 1 and 3, rock cores were extracted below the boring refusal depths. The rock cores are generally described as a mixture of biotite gneiss and schist. The competency of the rock is generally good at Boring No. 1; however, at Boring No. 3 the shist at the rock surface appears to contain numerous soil seams the lower the overall competency. Copies of the individual boring logs are attached. Based upon the boring data, it would appear that competent rock for the west abutment can be expected to be around 15 feet. At the east abutment, varied conditions are indicated based upon the boring data. At Boring No. 2, auger refusal was encountered at a depth of 2½ feet below a thin veneer of fill. At Boring No. 3, made about 12 feet away, auger refusal was encountered at a depth of about 7 feet. It is possible that the shallower refusal at Boring No. 2 was the result of rock in the fill. Nevertheless, what the rock cores indicate is the upper rock surface is of lower competency and prone to numerous soil seams. Competent rock at this abutment appears to begin around 25 feet. Any underpinning and/or lateral tie-back system will need to penetrate the competent rock vertically for bearing and laterally for support.
Geotechnical Engineering Special Inspections CMT Environmental Services
Adapted from Habersham County GIS Maps
SITE LOCATION PLAN
PARDUE MILL BRIDGE SITE NORTH HOLLAND DRIVE JEFFERSON, GEORGIA
DATE : 12/31/2020 REPORT NO. 80236
DRAWN BY : AGM PROJECT NO. 12973G
HORIZ. SCALE : NTS PLATE NO. 1
SITE
Adapted from Habersham County GIS Maps
APPROXIMATE BORING LOCATION
BORING LOCATION PLAN PARDUE MILL BRIDGE SITE
NORTH HOLLAND DRIVE JEFFERSON, GEORGIA
DATE : 12/31/2020 REPORT NO. 80236
DRAWN BY : AGM PROJECT NO. 12973G
HORIZ. SCALE : NTS PLATE NO. 2
GMotes
Typewritten text
1
GMotes
Typewritten text
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GMotes
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ASPHALT
(GM) GRADED AGGREGATE BASE(ML) FILL - FIRM RED-BROWN SANDY SILT WITH TRACE CLAYAND ROCK FRAGMENTS (MOIST)
(SM) FILL - FIRM BROWN SILTY FINE SAND TO SANDY SILTWITH TRACE CLAY AND ROCK FRAGMENTS
(SM) PARTIALLY WEATHERED ROCK SAMPLED AS VERYDENSE TAN-BROWN MICACEOUS SILTY FINE SAND
ROCK SAMPLED AS THICKLY BEDDED TAN, GRAY AND WHITEMICA SCHIST TO GNEISS WITH MULTIPLE THIN SOIL SEAMSAPPROXIMATELY 1-INCH THICK (REQ 95%, RQD 87%)
BORING TERMINATED AT 25 FEETBottom of borehole at 25.0 feet.
14
100
2-3-4(7)
5-3-3(6)
10-34-50/2"
50/3"
NOTES
GROUND ELEVATION
LOGGED BY JWR
DRILLING METHOD Automatic Hammer
DRILLING CONTRACTOR Drilling Solutions GROUND WATER LEVELS:
CHECKED BY AGM
DATE STARTED 12/7/20 COMPLETED 12/7/20
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
HOLE SIZE inches
FINES CONTENT (%) 20 40 60 80
20 40 60 80
PL LLMC
DE
PT
H(f
t)
0
5
10
15
20
25
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AP
HIC
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MATERIAL DESCRIPTION
SA
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BLO
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S(N
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PO
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PE
N.
(tsf
)
DR
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WT
.(p
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SPT N VALUE 20 40 60 80
PAGE 1 OF 1BORING NUMBER 1
CLIENT JM Smith Engineering, LLC
PROJECT NUMBER 12973G, 80236
PROJECT NAME Pardue Mill Road Bridge Repair SE
PROJECT LOCATION Demorest, Georgia
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JSouthern Geotechnical Consultants, LLC2660 White Sulphur Road / 14476 Duval Place West Suite 803Gainesville, Georgia 30501 / Jacksonville, Florida 32218Telephone: 770.536.5220 / 904.374.2252
>>
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ASPHALT
(GM) GRADED AGGREGATE BASE
(SM) FILL - VERY DENSE BROWN-GRAY MICACEOUS SILTYFINE SAND WITH ROCK FRAGMENTS
AUGER REFUSAL AT 2.5 FEETBottom of borehole at 2.5 feet.
8 6-5-50/1"
NOTES
GROUND ELEVATION
LOGGED BY JWR
DRILLING METHOD Automatic Hammer
DRILLING CONTRACTOR Drilling Solutions GROUND WATER LEVELS:
CHECKED BY AGM
DATE STARTED 12/10/20 COMPLETED 12/10/20
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
HOLE SIZE inches
FINES CONTENT (%) 20 40 60 80
20 40 60 80
PL LLMC
DE
PT
H(f
t)
0
1
2
GR
AP
HIC
LOG
MATERIAL DESCRIPTION
SA
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BE
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%(R
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BLO
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S(N
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PO
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(tsf
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SPT N VALUE 20 40 60 80
PAGE 1 OF 1BORING NUMBER 2
CLIENT JM Smith Engineering, LLC
PROJECT NUMBER 12973G, 80236
PROJECT NAME Pardue Mill Road Bridge Repair SE
PROJECT LOCATION Demorest, Georgia
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JSouthern Geotechnical Consultants, LLC2660 White Sulphur Road / 14476 Duval Place West Suite 803Gainesville, Georgia 30501 / Jacksonville, Florida 32218Telephone: 770.536.5220 / 904.374.2252
>>
ASPHALT(GM) GRADED AGGREGATE BASE(SM) FILL - VERY STIFF RED-BROWN MICACEOUS SILTY FINESAND TO SANDY SILT WITH TRACE CLAY
(SM) FILL - FIRM TAN-BROWN SLIGHTLY MICACEOUS SILTYFINE SAND TO SANDY SILT WITH TRACE CLAY
ROCK SAMPLED AS THICKLY BEDDED GRAY AND WHITEGNEISS (REQ 98%, RQD 97%)
SOIL SEAM
ROCK SAMPLED AS THINLY BEDDED TAN, GRAY AND WHITEMICA SCHIST TO GNEISS WITH MULTIPLE SOIL SEAMSRANGING FROM APPROXIMATELY 2-INCHES TO 1 FOOT THICK(REQ 67%, RQD 64%)
BORING TERMINATED AT 30 FEETBottom of borehole at 30.0 feet.
12-16-14(30)
5-4-2(6)
NOTES
GROUND ELEVATION
LOGGED BY JWR
DRILLING METHOD Automatic Hammer
DRILLING CONTRACTOR Drilling Solutions GROUND WATER LEVELS:
CHECKED BY AGM
DATE STARTED 12/10/20 COMPLETED 12/10/20
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
HOLE SIZE inches
FINES CONTENT (%) 20 40 60 80
20 40 60 80
PL LLMC
DE
PT
H(f
t)
0
5
10
15
20
25
30
GR
AP
HIC
LOG
MATERIAL DESCRIPTION
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PO
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PE
N.
(tsf
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DR
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WT
.(p
cf)
SPT N VALUE 20 40 60 80
PAGE 1 OF 1BORING NUMBER 3
CLIENT JM Smith Engineering, LLC
PROJECT NUMBER 12973G, 80236
PROJECT NAME Pardue Mill Road Bridge Repair SE
PROJECT LOCATION Demorest, Georgia
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JSouthern Geotechnical Consultants, LLC2660 White Sulphur Road / 14476 Duval Place West Suite 803Gainesville, Georgia 30501 / Jacksonville, Florida 32218Telephone: 770.536.5220 / 904.374.2252
