preliminary report of geotechnical evaluation mebane …

PRELIMINARY REPORT OF GEOTECHNICAL EVALUATION

Mebane Site

Yadkinville, NC

GeoSci Job 00.150

PREPARED FOR

Mebane Enterprises Inc.

PREPARED BY GEOSCIENCE and TECHNOLOGY, P.A.

November, 2000

Mebane Site November, 2000 Preliminary Geotechnical Evaluation Page i

CERTIFICATION

I hereby certify on this __________ day of __________________, 2000 that this report was prepared by me or under my direct supervision in compliance with generally accepted industry standards. _________________________ Jim Gorton Civil/Geotechnical Specialist __________________________ Carl von Isenburg, P.E. Senior Civil Engineer

Mebane Site November, 2000 Preliminary Geotechnical Evaluation Page ii

TABLE OF CONTENTS

page Certification .............................................................................................................................................. i 1. Introduction ............................................................................................................................................. 1 2. Background ............................................................................................................................................. 1 2.1 Regional Geology .............................................................................................................................. 1 3. Investigative Procedures ................................................................................................................................... 1 3.1 Sample Locations ............................................................................................................................... 1 3.2 Sampling Procedures ......................................................................................................................... 2 3.3 Soil Laboratory Procedures ................................................................................................................ 2 4. Results and Interpretation ................................................................................................................................. 3 4.1 Soil Conditions ................................................................................................................................... 3 4.2 Groundwater Conditions .................................................................................................................... 3 4.3 Bedrock ............................................................................................................................................. 3 4.4 General Suitability ............................................................................................................................. 3 5. Qualifications ............................................................................................................................................. 4 LIST OF FIGURES (after the body of the report) 1 Site Location Plan 2 Boring Location Map APPENDIX A Soil Laboratory Reports B Boring Logs C Excerpt from ASTM D 2487 Classification of Soils for Engineering Purposes

Mebane Site November, 2000 Preliminary Geotechnical Evaluation Page 1

1. Introduction The proposed commercial development is located on the north side of Highway 421, adjacent to the new interchange near Yadkinville, North Carolina (Figure 1). The property is bounded to the north by a church and Shacktown Road beyond, east by NCDOT property, south by Highway 421, and the west by the new interchange. The proposed use of the site is for commercial properties. This preliminary geotechnical report presents baseline geotechnical data in support of design, by others, of the building foundation and site work. Additional geotechnical testing is warranted once the exact building locations are finalized and located in the field. Figures are located after the main body of the report. Appendix A presents results of the soil laboratory analyses, Appendix B presents the boring logs. Appendix C presents an excerpt from American Society for Testing and Materials (ASTM) D 2487 Classification of Soils for Engineering Purposes. GeoSci performed ten soil penetration test (SPT) borings, and collected disturbed samples for classification and laboratory analysis. These are designated B-1 through B-10. Figure 2 depicts the approximate location of these borings. 2. Background 2.1 Regional Geology The subject site lies in the southwest portion of the Sauratown Mountains anticlinorium, a northeast-southeast trending feature containing primarily late Ptoterozoic to Cambrian metasedimentary, and granitic rocks exposed in windows and remnant thrust sheets. According to the North Carolina Geologic map (Brown et al, 1985), the subject site lies near the contact of two lithologic units of late Ptoterozoic to Cambrian age characterized by metagraywackes (biotite gneiss), amphibolites, kyanite schist, with some quartz and microcline porphyroblasts. Biotite gneisses are interlayered with and gradational to muscovite and biotite schists. Locally, minor ultramafics and granitic rocks may occur. The nearest significant structural feature is an unnamed thrust fault separating the Sauratown Mountains anticlinorium from the other lithotectonic belts: The western extension of the Milton Belt (southeast), the Triassic Davie basin (south) and the Inner Piedmont (south and southwest). There were no rock outcrops observed at the time of the site work. 3. Investigative Procedures 3.1 Sample Locations The approximate locations of the borings are shown on Figure 2, Boring Location Map. The boring depths, N values, and other sampling results are presented in the boring logs, in Appendix B. The SPT and additional sampling points are located in accordance with the following table:


Designation Location Depth (ft) Additional Testing

B1 Northeast lot corner 31.5 Atterberg, Grain Size, Proctor

B2 East property line 17 B3 Southeast lot corner 26.5

B4a/b DOT culvert fill 29 B5 DOT fill east 24 Atterberg, Grain Size,

Proctor B6 Center of property 16.5 B7 West/center parcel border 16.5 B8 Center of west parcel 16.5 B9 Proposed roadway west 11.5 B10 Proposed roadway east 11.5

3.2 Sampling Procedures Borings were performed with a trailer mounted SIMCO 2400 drill rig. A six-inch hollow stem auger was used to advance the bore hole. Auger tailings were collected for the purpose of determining baseline compaction densities. Disturbed soil samples were obtained by means of the split-barrel sampling procedure in general accordance with the American Society for Testing and Materials (ASTM) Specification D 1586. Samples were taken at 5 foot intervals to the depth of the boring. In this procedure, a 2 inch outside diameter, 1-3/8 inch inside diameter split-barrel sampler is driven into the soil a distance of 18 inches by means of a 140 pound hammer falling 30 inches. The Standard Penetration Test (SPT) value, N, is the number of blows to drive the final 12 inches. This value correlates well with literature values for strength characteristics of cohesionless soils. Cohesive soils (clays) were not encountered, so we did not perform Shelby tube sampling (ASTM D 1587). All open borings were immediately closed. Closure was done by hand filling with remaining auger tailings. 3.3 Soil Laboratory Procedures GeoSci examined the soil samples in the laboratory, grouped the samples by soil strata, and selected representatives for Atterberg limit testing (ASTM D 4318), Laboratory Compaction Characteristics of Soil using Standard Effort (Standard Proctor, ASTM D 698) and particle size analysis (ASTM D 1140). These tested soils were classified according to ASTM D 2487 (Unified Soil Classification). The remaining soil strata were described in accordance with ASTM D 2488 (Description and Identification of Soils). Reports of soil laboratory analyses are included in Appendix A. The 5-6.5' sample from boring B1 is indicative of most of shallow soils that will likely be utilized as fill, and was tested for Atterberg limits, Particle size analysis, and Standard Proctor.


The results of the tests indicate that the soil is fine grained (69.6% passed the 200 sieve) and moderately inelastic. The soil is classified as fine sandy silt (ML). Auger tailings from the upper 10' of this boring were collected and combined into a composite sample. We performed baseline testing on the composite sample using ASTM D 698 (Standard Proctor). The results indicate an optimum moisture content of 19.5%, and a maximum dry unit density of 96.4 pounds per cubic foot. The 5-6.5' sample from boring B7 was analyzed using the same methods (Atterberg Limits, Standard Proctor and Particle size analysis). The results of the tests indicate that the soil is fine grained (58.6% passed the 200 sieve) and low in plasticity. The soil was classified as a sandy silt (ML). Auger tailings from the upper 5' of this boring were collected and combined into a composite sample for analysis using ASTM D 698 (Standard Proctor). The results indicate an optimum moisture content of 18.5%, and a maximum dry unit density of 99.7 pounds per cubic foot. Logs of the borings are included in Appendix B. The soil descriptions in the boring logs contain the two letter Unified Soil Classification (USC) group symbol. A description of the USC system is included in Appendix C. The stratification lines designating the interfaces between soil types are approximate; in-situ, the contact between material types may be transitional. The soil samples will be retained in GeoSci’s laboratory for a period of sixty (60) days after the date of this report, after which they will be discarded unless instructions as to their disposition are received. 4. Results and Interpretation 4.1 Soil Conditions ML soils are silts of low plasticity. These soils are the predominant type at the site comprising most of the deep soils and all of the shallow soils. The areas that were filled by the DOT recently are comprised of mixed soils, but are predominantly ML type soils. Some of the deep soils exhibit weathered rock characteristics, and are coarse grained and sand-like in nature. This may be an indication of proximity to bedrock in these locations. Virgin soils (borings B1, B2, B3, B6, B7, B8, B9, and B10) at the site exhibited medium to dense properties with blow counts (N values as determined by ASTM 1586) ranging from 13 to 44. The fill soils placed by the DOT (borings B4 and B5) during construction of the adjacent interchange display loose to dense properties, with N values ranging from 7 to 48. The 10' sample from boring B5 displayed the blow count of 7, which is considered fairly loose. All other sample depths in these borings displayed blow counts in excess of 13. 4.2 Groundwater Conditions


We did not encounter groundwater in any of our borings. The deepest boring was extended to a depth of approximately 30 feet below grade. The soil at this depth was characterized as moist, and is likely in close proximity to the water table. Surface water, evidently spring fed, is present in the existing gully between borings B5 and B6. 4.3 Bedrock There were no outcrops of bedrock observed at the site. Auger refusal, which can be a rough indicator of bedrock proximity, was encountered in borings B2, B3, B4a, and B5, but occured at depths greater than 15 feet below existing grade. Further, the refusal encountered in boring B4a was most likely due to a discrete boulder. This is supported by the results of boring B4b, which was performed by moving the drill rig approximately 5 feet away from boring B4a, and was successfully extended past the impediment that caused refusal.

4.4 General Suitability Soil strength is approximated by relating N values, and correlating soil index properties with literature values. These correlation's are reliable with granular soils, but less so with clays. In all but the most critical applications, N-values can be used as an indication of strength for foundation design on granular soils. ML type silts comprise much of the shallow soils and are low in plasticity. The relatively high blow counts are an indication of sufficient bearing capacity, but good engineering practice requires that additional testing be performed once the actual locations of the structures are determined. Based on our preliminary investigation, the areas tested are generally suitable for standard construction (shallow footings) except for the area near boring B5, which is borderline in compaction. The fill in the vicinity of boring B5 may not be suitable for traditional footings, but can be addressed during the site grading phase of the project by removing and replacing the soil as engineered fill. The layout of the site is such that additional grading is warranted in this area with respect to the adjacent creek. Further, there was no shallow groundwater or bedrock encountered. The soil that is proposed to be cut was tested for baseline compaction data, and is generally suitable as engineered fill. 5. Qualifications The purpose of this report is to evaluate the existing subsurface conditions with regard to preliminary geotechnical suitability with respect to the project and design loads as described to us. When construction begins, if deviations from the soils encountered in our borings are observed, or if there are any significant changes in the size, design, or location of any proposed structures or, if changes in the planned construction from the concepts previously outlined occur, or, if changes in the design parameters stated in this report occur, the conclusions and recommendations contained in this report shall not be considered valid unless these changes have been reviewed and our conclusions and recommendations reevaluated or modified, in writing. Additionally, we recommend that GeoSci or another qualified firm be retained to perform on-site


review of foundation conditions during the construction phase of this project. Further, should any unforeseen event change the environmental conditions of the site prior to construction, a reassessment of the site, in writing, will be required.

River Ridge Site August, 2000 Preliminary Geotechnical Evaluation Figures

FIGURES

870

880

900

890

890

900

910

900

900

890

890

870

870

= 845.2'Headwall

51" CSP

36" RCP

INV. = 843.0'

INV. = 857.2'

30" CSP

24" RCP

INV. = 878.0'

INV. = 885.7'

INV. = 886.6'

INV. = 887.2'

15" RCP

INV. = 881.0'

30" CSP

36"

CSP

18" CSP

EXISTING CULVERT

PONDW.E. 885.7

CHORD= N 75°16'45"W 268.40'

S 01

°35'

04"W

434

.72'

S 15

°37'

14"W

324

.65'

S 55°25'24"W

638.

39'

36.0

4'90

.01'

764.

43'

764.

43'

764.

43'

5

4

3

2

1

216.13'

N 54°40'39"W

200.89'

N 52°41'37"W

Arc 270.76' Rad 590.54'

217.61'N 00°22'19"E

91.08'N 43°05'14"W

86.90'N 88°24'55"W

S 87°10'13"E 889.47'

60.01'

802.45'

27.01'

CHORD= N 86°37'43"W 546.81'Arc 546.82' Rad 19098.53'

N 87°26'56"W 465.04'

N 87°26'56"W 701.98'

S 03

°17'

12"W

764

.43'

S 86°55'22"E 383.61'

S 04

°10'

46"W

125

.35'

5/8" IRF

3/4" IRS

5/8" IRF

1-1/4" IPF

5/8" IRF

1-1/4" IPF

C/A

C/A

C/A

C/A

C/A

access road.DOT provided

El: 902.684E: 1516545.4628N: 866976.0202

TP NAILPt#: 10

El: 891.010E: 1516901.3051N: 866133.2960Desc: TP nailPt#: 5

El: 875.521E: 1516546.1450N: 866065.3674TP nailPt#: 4

El: 864.499E: 1515652.7362N: 866110.5604

TP nailPt#: 3

E: 1515661.3853N: 866055.8874

DOT BL-7 diskPt#: 180

PAVE

D

STRE

ET

U. S. 421U. S. 421

EXISTING 36" CMP

PROPOSED 36" CMPL=245 FT

N

eTG ence

chnologyeoSci

, P. A.&

"Practical Engineering &Environmental Solutions"

Winston-Salem, NC (336) 896-1300

Boring Location Map

Title:

Project:MEBANE SITE

DEVELOPMENT

Scale:

Job No.: Location: Figure No.:

1" = 100'

00.150 YADKINVILLE, NC 2

B1

B2

B3

B4aB4b

B5

B6

B7

B8

B9B10

River Ridge Site August, 2000 Preliminary Geotechnical Evaluation A

APPENDIX A

Laboratory Reports

River Ridge Site August, 2000 Preliminary Geotechnical Evaluation B

APPENDIX B

Boring Logs

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %

Standard Penetration

UNCONFINED COMPRESSIVE STRENGTH (TON/FT2)

Boring Number Boring StartedClient Boring Completed

Geologist/Engineer

Boring Description Job Number

Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation

Description of Materials

The stratification lines represent approximate boundaries between soil types. In-situ, transitions may be gradual.

Water Table Data: Depth Below Surface App'dAugerRigForemanDrilling Contractor

GeoScience & Technology, P.A.8/18/00B1

6" augerSimcoGeoSci

Boring Terminated @ 31.5'

RJW

RJW

Mebane Enterprises, Inc.

Northeast lot corner

White-brown; none; dry; firm; laminated; ML.

15

Mebane Site Development

Red-brown; none; dry; firm; stratified;69.6% passed 200 sieve, LL=40, PI=3, Sandy Silt (ML).

5-6.5SS

8/18/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

13

16

FINE GRAINED SOILS: COLOR; ODOR; MOISTURE; CONSISTENCY; STRUCTURE; COMMENTS:

18

15

50/5

Grey-brown; none; moist; firm; stratified; weathered rock, ML.

20-21.5S-4 SS

25-26.5S-5 SS

30-31.5S-6 SS

5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci

Auger Refusal @ 17'

RJW

RJW


East property line

Grey-brown; none; dry; firm; lensed; ML.

15


Red-brown; none; dry; firm; laminated;ML.

5-6.5SS

8/18/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

13

50/4


5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


Southeast lot corner

Orange-brown; none; dry; firm; homogeneous; MH.

14


Red-brown; none; dry; firm; laminated; ML.5-6.5SS

8/18/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

15

13


18

13

Grey-brown; none; dry; firm; stratified; ML.20-21.5S-4 SS

25-26.5S-5 SS

5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation




GeoScience & Technology, P.A.8/21/00B4b

6" augerSimcoGeoSci

Auger Refusal @ 29

RJW

RJW


DOT culvert fill (Former drainage path)

Orange-brown; none; dry; firm; heterogeneous fill; ML.

20


Medium brown; none; dry; hard; heterogeneous fill; largely ML.

5-6.5SS

8/21/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

16

13


26

48White/Orange/Grey; none; moist; lensed (4"); Weathered rock; SP.

20-21.5S-4 SS

25-26.5S-5 SS

5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci

Auger Refusal @ 24'

RJW

RJW


DOT fill east

Orange-brown; none; dry; firm; homogeneous; MH.

15


Red-brown; none; dry; firm; heterogeneous fill, ML5-6.5SS

8/21/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

7

16


15Brown; none; dry; firm; laminated; ML.20-21.5S-4 SS

5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


Center of property

Grey-brown; none; dry; hard; stratified; weatherd rock, SP.

25


Red-brown to brown; none; dry; hard; stratified;rock fragments, ML.

5-6.5SS

8/22/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

23

32


5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


West/center parcel border

Grey-brown; none; dry; firm; stratified; ML.

22


Red-brown; none; dry; hard; homogeneous;58.6% passed 200 sieve, LL=47, PI=9, ML/MH.

5-6.5SS

8/22/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

13

12


5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


Center of west parcel

Grey-brown; none; dry; firm; stratified; mottles @ 15', ML.

13


Orange-brown; none; dry; firm; laminated; ML

5-6.5SS

8/22/00

00.150

S-1

10-11.5S-2 SS

15-16.5S-3 SS

11

12


5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


Proposed roadway west

22


Black-brown; none; dry; hard;laminateded;weathered rock, ML.

5-6.5SS

8/22/00

00.150

S-1

10-11.5S-2 SS 44


5

10

15

20

25

10 20 30 40 50

10 20 30 40 50

1 2 3 4 5

X O X

PlasticLimit %

WaterContent %

LiquidLimit %




Geologist/Engineer


Project Name

Depthin

Feet

Sample#

Type

DepthFrom-

ToSurface Elevation





6" augerSimcoGeoSci


RJW

RJW


Proposed roadway east

White-Grey; none; dry; firm; homogeneous; weathered rock, SP.

23


Dark Grey with white; none; dry; hard; lensed (2"); SP.

5-6.5SS

8/22/00

00.150

S-1

10-11.5S-2 SS 12


5

10

15

20

25

River Ridge Site August, 2000 Preliminary Geotechnical Evaluation C

APPENDIX C

Excerpt From ASTM D 2487 Classification of Soils for Engineering Purposes

preliminary report of geotechnical evaluation mebane …

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