Soils Pavement Report.pdf

PREPARED BY

WILBUR SMITH ASSOCIATES

1301 GERVAIS STREET

COLUMBIA, SC 29201

PREPARED FOR

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

JUNE 7, 2010

PRELIMINARY SOILS AND PAVEMENT

REHABILITATION RECOMMENDATIONS REPORT

NATCHEZ TRACE PARKWAY

SECTIONS 3H AND 3J

FROM MILEPOST 181 TO MILEPOST 204

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SOILS AND PAVEMENT REHABILITATION RECOMMENDATIONS REPORT

NATCHEZ TRACE PARKWAY SECTIONS 3H AND 3J

FROM MILEPOST 181 TO MILEPOST 204

CHOCTAW COUNTY, MISSISSIPPI

PREPARED BY

WILBUR SMITH ASSOCIATES

1301 GERVAIS STREET

COLUMBIA, SC 29201

PREPARED FOR

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDRAL LANDS HIGHWAY DIVISION

August 13, 2010

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Soils and Pavement Recommendations Report WSA Project No. 104271 Natchez Trace Parkway, Sections 3H & 3J Choctaw County, Mississippi FHWA Project No. PRA-NATR 3H23, J10 August 13, 2010 i

TABLE OF CONTENTS

Page

1.0 INTRODUCTION .......................................................................................................................... 1-1

1.1 GENERAL ...................................................................................................................................... 1-1

1.2 PROJECT DESCRIPTION ........................................................................................................... 1-1

1.3 OBJECTIVE AND SCOPE ........................................................................................................... 1-2

2.0 SITE AND GEOLOGIC CONDITIONS ...................................................................................... 2-1

2.1 SITE CONDITIONS ...................................................................................................................... 2-1

2.2 REGIONAL GEOLOGY ............................................................................................................... 2-1

3.0 FIELD AND LABORATORY EXPLORATION ........................................................................ 3-1

3.1 PAVEMENT CORING AND SOIL BORINGS ........................................................................... 3-1

3.2 LABORATORY TESTING PROGRAM ..................................................................................... 3-2

3.2.1 Moisture Content .................................................................................................................. 3-2

3.2.2 Physical Properties ................................................................................................................ 3-2

3.2.3 Compaction and California Bearing Ratio ......................................................................... 3-2

4.0 PAVEMENT SURFACE AND SUBGRADE CONDITIONS .................................................... 4-1

4.1 PAVEMENT CONDITION SURVEY RESULTS....................................................................... 4-1

4.2 PAVEMENT CORING RESULTS ............................................................................................... 4-2

4.3 STRATEGRAPHY ......................................................................................................................... 4-3

4.4 GROUNDWATER CONDITIONS ............................................................................................... 4-3

4.5 PAVEMENT NONDESTRUCTIVE TESTING .......................................................................... 4-3

5.0 PAVEMENT ANALYSES AND RECOMMENDATIONS ........................................................ 5-1

5.1 ANALYSES METHOD .................................................................................................................. 5-1

5.2 TRAFFIC DATA ............................................................................................................................ 5-1

5.3 PAVEMENT OVERLAY CALCULATIONS ............................................................................. 5-2

5.4 PAVEMENT REHABILITATION ALTERNATIVES .............................................................. 5-3

5.4.1 Natchez Trace Parkway MP 181 to MP 192.8 and Parking Area 1 .................................. 5-3

5.4.2 Natchez Trace Parkway MP 192.8 to MP 204 and Parking Areas 2, 3 and 4 .................. 5-4

5.4.3 Parking Area 5 ...................................................................................................................... 5-4

5.4.4 Jeff Busby Park ..................................................................................................................... 5-4

5.4.5 Intersecting Roads ................................................................................................................. 5-4

5.4.6 Pavement Repair Recommendations ................................................................................... 5-5

5.4.7 Paving Materials Recommendations ................................................................................... 5-6

6.0 REFERENCES ............................................................................................................................... 6-1

APPENDIX A: SITE LOCATION MAP

BORING LOCATION PLAN SHEETS

APPENDIX B: SOIL TEST BORING RECORD KEY SHEET

SOIL TEST BORING LOGS

PAVEMENT CONDITION SURVEY FORMS

APPENDIX C: LABORATORY TEST RESULTS

APPENDIX D: PHOTOGRAPHS

APPENDIX E: PAVEMENT ANALYSES

APPENDIX F: FWD TEST REPORT

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EXECUTIVE SUMMARY

Wilbur Smith Associates (WSA) is providing design services to the Eastern Federal Lands Highway Division (EFLHD) of the Federal Highway Administration for the resurfacing and rehabilitation of 23 miles of Natchez Trace Parkway from Milepost 181 to Milepost 204, including five parking areas/pull offs and Jeff Busby Park. This segment of roadway is maintained by the U.S. National Park Services (NPS). The WSA Geotechnical staff performed geotechnical exploration as part of the Conceptual Plan Phase (Phase II) of the project. The exploration included a pavement condition survey, nondestructive Falling Weight Deflectometer (FWD) testing, pavement coring, soil boring program, and laboratory testing.

From Mileposts 181 to 192.8, the pavement consists of chip seal surface; significant block cracking and rutting were observed in this segment. Subgrade failure was also observed at two locations.

From Mileposts 192.8 to 204, the road appears to have been overlaid in the past few years. The road surface condition in this segment appears to be in fairly good condition.

The soil borings indicate that the pavement subgrade consists of mostly medium dense SILTY SAND (SM). The silty sand layer is underlain by a soft to firm CLAYEY SAND (SC) or CLAY (CL) layer. Groundwater was not encountered within the boring depths at the time of drilling.

Falling Weight Deflectometer (FWD) non-destructive testing was used to determine the structural properties of the pavement structures. Based on the FWD test results and the pavement thicknesses from the core borings, the Parkway was divided into three relatively uniform sections as detailed in Section 4.5 of the report.

Pavement overlay calculations were performed in accordance with the 1993 AASHTO Design Guide.

The DARWin computer program was used in the analyses. Based on the analyses results, a 1.5-inch overlay is recommended between MP181 and 192.8 to improve the pavement surface condition and ride quality. Overlay is not structurally required for the Parkway pavement between MP 192.8 and

204. However, based on our discussions with the EFLHD and the NPS, a 1.5-inch overlay is recommended based on the project requirements and to maintain a uniform pavement surface throughout the project alignment. A 1.5-inch overlay is also recommended for parking areas 1 through 4 and for Jeff Busby Park. Variable milling should be performed at the curb sections in these areas to maintain a curb reveal of 6 inches. Overlay for Parking Area 5 is not required because the pavement has an adequate structural number and the pavement surface which was overlaid in the past 12 to 18 months is in a very good condition. However, based on discussions with the EFLHD and the NPS, a 1.5-inch overlay is recommended. Variable milling should also be performed to maintain a 6-inch curb reveal.

1-1

1.0 INTRODUCTION

1.1 GENERAL

Wilbur Smith Associates (WSA) is providing design services to the Eastern Federal Lands

Highway Division (EFLHD) of the Federal Highway Administration for the resurfacing and rehabilitation of 23 miles of pavement along the Natchez Trace Parkway, five parking areas/pull offs and Jeff Busby Park. The WSA Geotechnical staff performed geotechnical exploration as part of the Conceptual Plan Phase (Phase II) of the project. This report contains the results of our pavement investigation including descriptions of the subsurface conditions encountered and results of field and laboratory testing. This report provides recommendations for the design and construction of the proposed pavement rehabilitation.

1.2 PROJECT DESCRIPTION

This project consists of resurfacing and rehabilitation of approximately 23 miles of Natchez Trace

Parkway between Mileposts 181 and 204, including five parking areas (Parking Areas 1 through 5), and Jeff Busby Park. Jeff Busby Park consists of approximately 1.9 miles of paved roads that provide access to overlook, picnic area, campground and the overlook parking area. There are nineteen (19) bridges within the project limits. Pavement rehabilitation work for the Parkway may include milling of the existing surface, resurfacing, pavement overlay or other pavement rehabilitation methods. Parking areas and bridges consist of curb sections and require milling before resurfacing to maintain a 6-inch curb reveal. Other improvements such as additional signs, drainage improvements, pavement marking, wheelchair-accessible ramps, striping, symbols, and signing may be required.

No as built drawings were available at the time of our exploration. Based on the information provided by EFLHD, we understand that the Natchez Trace Parkway pavement in this area was constructed in 1978. Parts of the section were overlaid in 1995 and the majority of the section was chip sealed in 1997 and 1998. Based on existing drawings for the Pigeon Roost Parking Area

(Parking Area 5- Reference 1), it appears that this parking area and an adjacent 850+/- feet of the parkway were overlaid in 2008 to 2009. Based on our field observations, it appears that other portions of the Parkway have been overlaid after 1998.

1-2

1.3 OBJECTIVE AND SCOPE

The objectives of this study were to evaluate existing pavement surface and subgrade conditions and provide recommendations for pavement overlay and rehabilitation. The scope of this investigation included:

• Field reconnaissance.

• Nondestructive testing (NDT) program of pavements.

• Condition survey of the existing pavements.

• Pavement coring and soil boring program to investigate pavement subgrade conditions.

• Laboratory testing program.

• Recommendations for pavement overlay and rehabilitation.

The work was performed in general conformance with Chapters 6 and 11 of the EFLHD Project

Development and Design Manual (PDDM) (Reference 2).

2-1

2.0 SITE AND GEOLOGIC CONDITIONS

2.1 SITE CONDITIONS

The project is located along Natchez Trace Parkway, a historical path that extend roughly 440 miles from

Natchez, Mississippi to Nashville, Tennessee. The project begins at Milepost 181 located just north of

French Camp, MS and extends north to Milepost 204 located south of Mathiston, MS. The 23-mile alignment consists of two, 11-ft wide lanes of traffic and is paved with asphalt. The roadway runs through scenic wooded areas that are located mostly in rolling terrain topography. The alignment crosses numerous roads with at-grade intersections or bridge structures.

Nineteen (19) bridge structures exist within the project limits. The concrete bridge structures carry the parkway over intersecting roads or water bodies. The majority of roadway alignment appears to be on embankments with varying side slopes. The roadway shoulders are grassy and are variable in width. The tree line is typically about 20 feet or more from the edge of pavement. Shoulder drop-off exceeding 2 inches was observed in many locations along the alignment.

Pipe or box culverts cross beneath the roadway embankments at numerous locations. From MP 181 to about MP 192.8, the road consists mostly of chip seal surface that, we understand, was placed in 1997-

1998. However, two segments near MP 184 and MP 185 appeared to have been more recently overlaid with asphalt. From about MP 192.8 to 204 the road appeared to have been overlaid in the past 4 to 6 years.

2.2 REGIONAL GEOLOGY

The Natchez Trace Parkway in Choctaw and Webster County, Mississippi, is located within the Eastern

Gulf of Mexico coastal plain physiographic province of Mississippi. The coastal plain in this area of

Mississippi is characterized by flat to rolling topography, with formations that range in age from the

Paleocene to the Holocene. Geologic maps of the area, between State Route 415 and US 82, indicate the predominant geologic units in the area are the Wilcox and Midway Groups, both Paleocene-aged units.

The Wilcox Group is composed of the Tuscahoma and Nanafalia Formations, of which the Nanafalia can be further sub-divided into the Grampian Hills and Gravel Creek Sand Members. The Midway Group is composed of the Naheola Formation and can be further sub-divided into the Coal Bluff and Oak Hill

Members. Between many of the geologic map units is a Holocene-aged alluvium commonly found in the

2-2 creek and river basins, which is characterized by sand, flood plain sands and silts. Each of the geologic map units mentioned above are described in more detail below.

The Tuscahoma Formation is predominantly a very fine to coarse-grained sand that is dark greenish-gray to light gray in color and weathers to a reddish-orange to pale yellow-orange. It is interbedded to interlaminated with clay and silt that is light olive-gray to brownish-black in color and weathers to various shades of red, gray, brown, or white.

The Grampian Hills Member of the Nanafalia Formation is predominantly a clay and silt that is medium gray to pale-green in color and weathers to various shades of red, brown, and gray. It is interbedded to interlaminated with very fine to medium-grained sand that is dark greenish-gray to medium gray in color and weathers reddish-orange to pale yellowish-orange. The Gravel Creek Sand Member of the Nanafalia

Formation is predominantly a very coarse to fine-grained sand, that is medium gray to very light gray in color and weathers to a reddish-orange to pale yellowish-orange.

The Coal Bluff Member of the Naheola Formation, which is predominantly a very fine to very coarse-grained sand that is dark gray to light gray in color and weathers to a pale yellowish-orange to reddish-orange. It is interbedded to interlaminated with clay and silt that is dark gray to light gray in color.

The Oak Hill Member of the Naheola Formation is predominantly a clay that is brownish-black to medium gray in color and weathers to a grayish-brown to white. It is interbedded or interlaminated with a fine to coarse-grained sand that is dark gray to greenish-gray in color and weathers to a reddish-orange to light yellowish-orange.

3-1

3.0 FIELD AND LABORATORY EXPLORATION

3.1 PAVEMENT CORING AND SOIL BORINGS

A combined total of 33 pavement cores and soil test borings were drilled to investigate the subsurface conditions within the existing alignment for the proposed asphalt overlay of Natchez Trace Parkway.

Borings B-181 to B-204 were cored and drilled between mileposts 181 and 204, while borings P-1 to P-5 were cored and drilled at five different parking areas along the parkway, and borings JB-1 to JB-4 were cored and drilled along the roadway within Jeff Busby Park. The boring locations are shown on the

Boring Location Plans, which are included in Appendix A. Boring locations were staked out by the WSA

Geotechnical staff based on the survey stations marked on the pavement by the WSA Surveying staff.

Drilling was performed under our supervision on the May 4 -5, 2010. The borings were performed by our drilling subcontractor Burns Cooley Dennis, Inc. (BCD) using a pavement coring machine mounted on the back of a pickup truck and a Simco 2800 HS (HT) truck mounted drill rig. The borings that were drilled with the truck rig were advanced using a 2.25-inch inside diameter solid stem auger. The terminal boring depths ranged from 5 to 6.5 feet below the existing surface.

Groundwater level measurements were taken immediately after completion of drilling at all locations;

however none of the boring locations observed groundwater. All borings were backfilled with soil cuttings and then patched with asphalt. The Boring Records for this subsurface investigation are provided in Appendix B. Table 4.2, which follows in this report provides information on the asphalt cores.

Soil sampling and standard penetration testing (SPT) was performed in general accordance with ASTM

D1586. In these borings soil samples were obtained at regular intervals using a standard 1.4-inch I.D., 2-inch O.D., split-tube sampler. The sampler was first seated 6 inches to penetrate any loose cuttings, and then driven an additional 12 inches with blows of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final 12 inches was recorded and is designated the

“penetration resistance” and measured in blows per foot (bpf). In addition, a grab sample was obtained from the auger flights between regular SPT samples to verify any soil strata change. The soil samples obtained from the split-tube sampler were visually classified in the field by a WSA Geotechnical professional and then transported to the geotechnical laboratory. The purpose of using SPT procedures was to obtain an indication of density of the soil deposits.

3-2

3.2 LABORATORY TESTING PROGRAM

Laboratory testing on selected samples was performed to determine physical properties of the soils and to verify visual classifications. Results of the field and laboratory testing were used to provide estimates for design parameters used in our analyses. The laboratory tests were performed by our subcontractor BCD in general accordance with applicable ASTM standards. The results of the laboratory tests are presented in Appendix C, and a brief summary of the laboratory test results is presented in the following sections.

3.2.1 Moisture Content

Moisture content determinations were performed on 37 pavement subgrade samples obtained from the borings. The moisture contents of the samples ranged from 8 to 25 percent, although moisture contents between 10 and 16 percent are more typical.

3.2.2 Physical Properties

Grain size analysis tests or percent fines tests were performed for 37 samples. Four of the tested samples were found to be fine grained with percent fines ranging from 57 to 85 percent, while the remaining 33 samples were coarse grained with percent fines ranging from 12 to 37 percent.

3.2.3 Compaction and California Bearing Ratio

Modified Proctor compaction and CBR tests were performed on three bulk samples from the borings. The maximum dry density, optimum moisture content and CBR test results for the combined samples are tabulated below.

TABLE 3.2.3. Compaction and CBR Test Results

Sample Classifica-tion

% fines

Max.

Dry

Density (pcf)

Optimum Moisture (%) CBR at 95% compaction 0.1” Penet.

B-185 SM 17 120 10 23

B-193 SM 24 129 8 30

B-200 SM 20 119 10 27

4-1

4.0 PAVEMENT SURFACE AND SUBGRADE CONDITIONS

4.1 PAVEMENT CONDITION SURVEY RESULTS

A visual survey of pavement conditions was performed on April 26-28, 2010 by our Geotechnical staff. The survey was performed by driving the road in both directions at slow speed and occasionally stopping to closely observe distresses. Pavement distress types were examined in the condition survey and categorized using the SHRP Manual (SHRP, 1993- Reference 3). The detailed pavement condition survey sheets are included in Appendix B. Photographs showing samples of the pavement distresses are provided in Appendix D.

The types and extent of distresses observed were recorded by our staff. From MP 181 to about MP

192.8 including Parking Areas 1 and 2, the pavement surface consists of a chip seal. A majority of the pavement along this segment of the parkway has block cracking and transverse/longitudinal cracking. Low severity rutting was observed in the wheel paths along a majority of this segment.

Localized edge cracking shaped as a half moon was observed at some locations and typically occurred near embankment slopes. Edge failure/cracking is typically caused by weak subrade near the edge of the embankment. Also, very weak subgrade conditions or subgrade failure appear to have caused a pavement shear failure approximately 1,000 feet north of MP 185 (both lanes- MP

185.16 to 185.26) as shown in the photographs in Appendix D. Noticeable pavement surface settlement caused by weak subgrade was also observed about 300 feet north of MP181

(Northbound lane MP 181.06 to 181.08), immediately after Parking Area 1.

From MP 192.8 to the end of the project including Parking Areas 3 and 4, the pavement appeared to have been overlaid in the past 4 to 6 years. Overall, the pavement condition in this segment is fair to good. Low severity block cracks appeared to be reflecting to the pavement surface. Small pumps and sags exist at the reflected cracks locations. Occasional low severity rutting was also observed. Parking Area 5 has been overlaid in the past 18 months and the pavement surface is in a very good condition.

Jeff Busby Park pavements consist of a chip seal surface. These pavements appear to have the worst surface condition, especially the parking at the park entrance. Block cracking, potholes and surface depressions are prevalent.

4-2

4.2 PAVEMENT CORING RESULTS

Pavement coring was performed at the boring locations. A summary of the pavement thickness at the core locations is provided in Table 4.2 and photographs showing the recovered pavement cores are provided on the boring logs in Appendix B.

TABLE 4.2. Natchez Trace Parkway Asphalt Core Info

Boring No. Milepost Station* Lane

Asphalt Thickness (inches)

Comments

P-1 181 01+50 4.0 Parking Area

B-181 181 15+00 SB 6.0

B-182 182 5+00 NB 5.5

B-183 183 5+00 SB 5.0

B-184 184 5+00 NB 10.5

B-185 185 5+00 SB 5.0

B-186 186 5+00 NB 5.0

B-187 187 5+00 SB 5.0

B-188 188 10+00 NB 6.0

B-189 189 5+00 SB 6.0

P-2 189 49+50 4.0 Parking Area

B-190 190 5+00 NB 5.0

B-191 191 5+00 SB 7.0

B-192 192 5+00 NB 4.5

JB-1 193 8.0 Jeff Busby Park JB-2 193 8.5 Jeff Busby Park JB-3 193 4.5 Jeff Busby Park JB-4 193 5.5 Jeff Busby Park

B-193 193 16+50 SB 8.5

B-194 194 5+00 NB 6.0

B-195 195 5+00 SB 8.0

B-196 196 5+00 NB 6.0

B-197 197 10+00 SB 7.0

B-198 198 5+00 NB 6.5

P-3 198 34+00 5.75 Parking Area

B-199 199 10+00 SB 7.25

B-200 200 5+00 NB 6.5

B-201 201 5+00 SB 6.5

P-4 201 19+25 8.0 Parking Area

B-202 202 5+00 NB 7.0

B-203 203 5+00 SB 7.0

P-5 203 29+00 5.5 Parking Area

B-204 203 50+00 NB 7.5

* Station number is referenced to the MP marker for both northbound and southbound lanes

4-3

4.3 STRATEGRAPHY

The subsurface conditions encountered in our borings are presented on the Soil Test Boring Logs in

Appendix B. The soil stratification is generally described below.

Stratum I - typically consist of SILTY SAND (SM). Occasionally, clayey sand or clay was encountered. The surficial soils extend to depths ranging from 3 to 5 feet beneath the existing ground surface and exhibit Standard Penetration Resistance Blow Counts (SPT-N values) ranging from 5 and 34 blows per foot (bpf). However, SPT values in the teens are more typical. Stratum I soils were typically dry to moist at the time of our exploration.

Stratum II – typically consists of soft to very stiff CLAYEY SAND (SC) and LEAN CLAY (CL).

Occasionally, FAT CLAY (CH) was encountered within this stratum. These soils were encountered beneath Stratum I soils in most borings and extended to the boring termination depths.

SPT N-values in this stratum ranged from 1 to 35 bpf, although blow counts ranging between 5 and

14 were typical. The soils within this stratum were typically moist.

4.4 GROUNDWATER CONDITIONS

Groundwater was not encountered within the depth of drilling in any of the borings during and immediately after completion of drilling. Groundwater level 24-hour after drilling were not taken because the borings were drilled in the road pavement and had to be backfilled immediately after completion of drilling. Fluctuations in rainfall, evaporation, construction activity, and the surface water runoff will cause variations in depths to groundwater.

4.5 PAVEMENT NONDESTRUCTIVE TESTING

A series of 861 nondestructive tests (NDT) tests were conducted along Natchez Trace Parkway, the five parking areas and Jeff Busby Park. NDTs were generally located on a 150-ft.longitudinal spacing staggered between the two lanes of the road. The testing was performed on April 26-28, 2010 by our subcontractor Engineering Research International (ERI). ERI utilized a KUAB

Falling Weight Deflectometer (FWD) to perform the testing in general accordance with AASHTO

T-256. Detailed of the test procedures and test results are provided in ERI’s Report, which is provided in Appendix F.

4-4

The primary purpose of NDT is to determine the structural properties of the pavement. The load response data resulting from the dynamic force simulates the effect of moving vehicle loads. The

NDT equipment used for the testing program was designed to generate a dynamic load on the pavement surface and measure the resultant vertical response of the pavement, including subgrade, base courses, and surface layers.

Based on the results of the NDT program and the pavement thicknesses, the Parkway was divided into three relatively uniform sections. ERI calculated the subgrade resilient modulus (Mr) and the effective pavement modulus (Ep). The calculated values are summarized in Table 4.5.

TABLE 4.5 Summary of Uniform Sections and NDT Results for the Parkway

Uniform Section Limits Asphalt Thickness

(inch)

Granular Base (inch)

Mr (psi)

EP (psi) From MP To MP

181.0 181.9 6.0 2.0 16,469 282,970

181.9 192.8 5.5 2.0 23,333 359,746

192.8 204.0 7.0 2.0 17,107 234,866

Based on procedures contained in the 1993 AASHTO Guide for Design of Pavement Structures

(Reference 4), a correction factor of 0.33 was used to adjust the resilient modulus (Mr). Since the testing was performed during the spring season, the in-situ Mr values should be conservative.

5-1

5.0 PAVEMENT ANALYSES AND RECOMMENDATIONS

5.1 ANALYSES METHOD

Results of the NDT and traffic projections were used in our structural analysis to identify alternatives for pavement rehabilitation. Our analyses were performed in accordance with the 1993

AASHTO design procedures using the DARWin 3.1 computer program. The AASHTO design is based on calculating the future structural number (SNf) necessary to support the anticipated traffic and then comparing that with the effective existing structural number (SNeff) to determine the required overlay thickness. The flexible pavement design analysis and overlay design analysis were for a 20-year performance period

5.2 TRAFFIC DATA

Traffic data for the parkway were obtained from the 2004 Natchez Trace Traffic Package report by the National Park Service (Reference 5). The report includes Average Annual Daily Traffic

(AADT) values for the Parkway for the years 1955, 1991, 1994, and 2003. The data indicates a trend of declining traffic volumes on the parkway from 1988 to 2003. For the year 2003, the report indicates an AADT of 764 vehicles per day (vpd) for the southern 15-mile segment of the Parkway

(from MS 413 to MS 9), compared to an AADT of 1230 during the year 1988. The report also indicates an AADT of 650 vpd for the northern 8-mile segment (from MS 9 to MS 82) for the year

2003, compared to 1,075 for the year 1988.

We have assumed the current AADT for the Parkway to be similar to the 2003 AADT. We have also assumed a traffic volume growth rate of 2% per year over the 20-year performance period.

The following data was used for the pavement analyses:

AADT Natchez Trace Parkway (2010) = 764 AADT Natchez Trace Parkway (2030) = 1070 AADT Parking Areas 1 through 5 (2010) = 150 AADT Parking Areas 1 through 5 (2030) = 210 AADT Jeff Busby Park and Parking areas (2010) = 250 AADT Jeff Busby Park and Parking areas (2030) = 350 Performance Period 20 years Standard Deviation = 0.49 (PDDM Section 11.2.2) Reliability = 0.75 (PDDM Section 11.2.2)

The rigorous ESAL calculation method in DARWin was used to calculate the future ESAL. The truck traffic was taken based on the information provided in Reference 5. Vehicle classes higher

5-2 than class 6 are not expected on this road. Detailed traffic calculations are in DARWin output sheets provided in Appendix E and a summary of the percentages of the individual vehicle classes used in our analyses for the Parkway pavement is provided in the Table 5.2.1.

Table 5.2.1. Vehicle Classes Used for Traffic Analyses

Vehicle Class

Percent of

ADT

Annual

Growth 1 6 2 2 80 2 3 10.5 2 4 1.5 2 5 1 2 6 1 2

Total 100

Based on this traffic data, the total estimate Equivalent Single Axle Load (ESAL) for the parkway pavement over the design period is about 124,000.

5.3 PAVEMENT OVERLAY CALCULATIONS

The DARWin computer program was used to calculate the required future pavement structural number for the uniform sections of Natchez Trace Parkway, Jeff Busby Park and the parking areas.

The required future structural number (SNf) was calculated in DARWin computer program based on the anticipated future ESAL, the subgrade resilient modulus from the FWD testing, and the initial and terminal serviceability Index values. The following parameters were used to estimate the required structural number:

Initial Serviceability = 4.2 (PDDM Section 11.2.1.1) Terminal Serviceability (Natchez Trace Parkway) = 2.5 (PDDM Section 11.2.1.1) Terminal Serviceability (Jeff Busby and Parking Areas) = 2.0 (PDDM Section 11.2.1.1)

The existing effective pavement structural number (SNeff) was also calculated by DARWin based on the FWD test results using the following equation:

SNeff 0.0045 √3 (1993 AASHTO 5.4.5)

Where D = total thickness of all pavement layers above the subgrade, inches EP = effective modulus of pavement layers above the subgrade

5-3

The required overlay structural number was then calculated by subtracting the existing structural number from the future required structural number. Table 5.3 provides a summary of the calculation results for different pavement sections.

TABLE 5.3 Summary of Pavement Overlay Calculations

(1) Although structural calculations indicate that overlay is not required, we recommend 1.5-inch overlay to rehabilitate the existing surface condition.

(2) Curb sections exist at the parking area. 1.5-inch milling should be performed in those areas before placing 1.5-inch overlay to maintain a 6-inch curb reveal.

(3) 1.5-inch milling was assumed in calculating SNeff for Parking Areas 1 through 5.

5.4 PAVEMENT REHABILITATION ALTERNATIVES

Condition survey data and the results of our overlay calculations were examined to evaluate the overall condition of the pavement and to provide pavement rehabilitation alternatives. The following paragraphs provide our recommendations for pavement overlay and rehabilitation.

5.4.1 Natchez Trace Parkway MP 181 to MP 192.8 and Parking Area 1

From MP 181 to MP 192.8, the parkway pavement consists of chip seal surface. The pavement in this area has deteriorated with significant block and longitudinal/transverse cracking, rutting and depressions. The roughness of the existing chip seal surface in this segment is causing noise and low ride quality for the users. Based on our calculations, a 1.5-inch overlay is recommended for

Pavement Section Asphalt (in)

Base (in)

Mr

(FWD

Test) (psi)

Mr (Design)

(psi)

EP (psi) SNeff SNf Recommended Overlay

SN Thickness (in)

Natchez Trace

Parkway

181.0 181.9 6.0 2 16,469 5,400 282,970 2.07 2.50 0.43 1.5

181.9 192.8 5.5 2 23,333 7,700 359,746 2.24 2.18 0 1.5 (1)

192.8 204.0 7.0 2 17,107 5,600 234,866 2.50 2.46 0 1.5 (1)

Jeff Busby – Entrance Parking Area

8 2 14,000 4,700 250,000 2.51 2.16 0 1.5 (1)

Jeff Busby - Overlook Parking and Access Rd.

5 2 14,000 4,700 173000 1.56 (2) 2.16 0.60 1.5

Jeff Busby - Picnic Area 8 2 15,000 5,000 90,000 2.02 (2) 2.11 0.09 1.5

Jeff Busby - Maintenance Rd.

5 2 16,000 5,300 181,000 1.78 2.06 0.28 1.5

Parking P-1 (MP 181) 4 2 13,000 5,000 82,000 1.20 (3) 1.88 0.68 1.5

Parking P-2 (MP 189) 4 2 31,000 7,000 200,000 1.18 (3) 1.65 0.47 1.5

Parking P-3 (MP 198) 5.7 2 17,000 5,700 122,000 1.31 (3) 1.79 0.48 1.5

Parking P-4 (MP 201) 8 2 12,000 4,500 89,000 1.31 (3) 1.96 0.65 1.5

Parking P-5 (MP 203) 5.5 2 13,000 4,300 136,000 1.53 (3) 1.99 0.46 1.5

5-4 this segment of the road. The very weak subgrade condition located on the northbound lane MP

181.06 to 181.08 should be repaired with full-depth patching. Similarly, the subgrade failure area from MP 185.16 to 185.26 (both lanes) should be repaired with a full-depth patching. The recommended section for the pavement patching is 1.5-inch asphalt surface course, 3-inch asphalt intermediate course and 4-inch aggregate base course. Variable milling should be performed at the curb sections in Parking Area 1 before placing the overlay to maintain a curb reveal of 6 inches.

5.4.2 Natchez Trace Parkway MP 192.8 to MP 204 and Parking Areas 2, 3 and 4

The pavement in this segment appears to have been overlaid within the past 4 to 6 years. The pavement surface seems to be in a general good condition. Based on our calculations, overlay will not be needed to achieve the required future structural number. However, based on our discussions with the EFLHD and the NPS staff, an overlay of 1.5 inches may be used based on the project requirements and to maintain a uniform surface throughout the entire project alignment. Variable milling should be performed at the curb sections in Parking Areas 2 through 4 before placing the overlay to maintain a curb reveal of 6 inches.

5.4.3 Parking Area 5

As indicated earlier, this parking area and an adjacent approximately 850-ft segment of the parkway were overlaid in 2008 to 2009. The pavement surface is in a very good condition and overlay would not be required. However, based on our discussions with the EFLHD and the NPS staff, an overlay of 1.5 inches may be used based on the project requirements and to maintain a uniform surface throughout the entire project alignment. Variable milling should be performed at the curb sections in Parking Area 5 before placing the overlay to maintain a curb reveal of 6 inches.

5.4.4 Jeff Busby Park

Pavement in Jeff Busby Park is in a poor condition. We recommend that a 1.5-inch milling be performed for the entrance parking, the overlook access road, the picnic area and the maintenance road prior to the placement of a 1.5-inch overlay. Also, potholes and localized failed conditions should be patched before placing the overlay.

5.4.5 Intersecting Roads

Pavement repair/overlay is required for all the side roads that cross the Parkway with at-grade intersections. The repairs/overlays required for the intersecting roads typically extend to about 50

5-5 feet or less on both sides of the Parkway. The limits of paving for intersecting roads are to the end of the curb sections, where they exist, or to the end of the existing pavement limits. A summary of the intersecting roads and the recommended repairs are provided in Table 5.4.5.

TABLE 5.4.5 Intersecting Roads Repair Recommendations

Intersection

MP/

Station

Intersecting Road Name

Curb

Pavement condition Notes Recommendation East Side West Side

181/ 42+00 Camp Rd Y Block cracking Block cracking 1.5” mill & overlay 181/ 42+00 Old Preuch Rd Y Block cracking Block cracking 1.5” mill & overlay

183/43+00 Seals Crossing N Block cracking, Rutting

Block cracking, Rutting, small potholes

1.5” mill & overlay, pothole patching

184/00 Miller Crossing N Block cracking Block cracking 1.5” mill & overlay

184/18+00 Ross Crossing N Block cracking, potholes

Block cracking, potholes

1.5” mill & overlay, pothole patching

185/34+00 Simpson crossing N Block cracking Block cracking 1.5” mill & overlay

186/40+00 Stewart Crossing Y Alligator & block cracking, Patching

Alligator & block cracking Full depth Patching

187/43+00 Henderson Weir N Block cracking Block cracking 1.5” mill & overlay 188/31+00 Smith Crossing N Block cracking Block cracking 1.5” mill & overlay 189/46+50 BYWY Crossing N Block cracking Block cracking 1.5” mill & overlay

190/50+00 Rt 415 Y

Alligator & block cracking, rutting, block cracking, patching

Alligator & block cracking, rutting, block cracking

Full depth Patching

191/42+00 Nobus crossing N Block Cracking, Potholes

Block Cracking, Potholes

1.5” mill & overlay, pot hole patching

200/42+00 Pollard Crossing N Block cracking Block cracking 1.5” mill & overlay

Pavement sections over bridge structures should be milled to a depth of 1.5 inches and then overlaid to maintain a curb reveal of 6 inches.

5.4.6 Pavement Repair Recommendations

Prior to overlay placement, all potholes should be patched and the deteriorated existing patches be repaired. Areas of alligator cracking should be saw-cut and then full-depth patched. Also, major cracks should be sealed. When milling and full depth patching are required, milling should be performed first and the top of the intermediate layer should be made flush with the surface of the milled pavement. Significant edge cracking should also be repaired by full depth patching of the pavement. Edge cracking is caused by loss of subgrade support typically typically in a crescent

5-6 shape within 2 feet from the edge of pavement. This loss of support may have been caused by the proximity of the pavement edge to a steep slope.

A minimum full-depth patch width of 5 feet is recommended. The steps for full depth patching include the following:

• Marking and cutting of the boundaries

• Breakup and removal of the pavement surface and affected base/sub base layers

• Preparation and compaction of subgrade

• Placement and compaction of new aggregate base layer

• Application of tack coat along the edges of the repair area

• Placement and compaction of asphalt intermediate and surface courses

Drop off of the unpaved shoulders should be repaired by placing a suitable aggregate and topsoil mixture to within ½ inch from the final pavement surface. Significant shoulder drop off is a safety concern and it also contributes to the loss of support near the pavement edge.

5.4.7 Paving Materials Recommendations

We recommend that the pavement overlay consists of superpave asphalt concrete surface mix with a 3/8-inch nominal maximum size aggregate (NMSA). We also recommend that the full-depth patching consist of a 1.5-inch superpave asphalt concrete surface course with a 3/8-inch NMSA and 3-inch superpave asphalt concrete intermediate course with a ¾ inch NMSA. Based on the anticipated traffic and MDOT practices, we recommend that a PG 67-22 asphalt binder be used for all asphalt concrete mixes.

6-1

6.0 REFERENCES

1. Pigeon Roost Creek Parking Area Paving, Project PRA-NATR 3H24 Design Drawings, US Department of the Interior, National Park Service, 2008

2. Federal Lands Highway Project Development and Design Manual (PDDM), US Department of Transportation, Federal Highway Administration (FHWA), 2008.

3. Distress Identification Manual for the Long-Term Pavement Performance Project. Startegic Highway Research Program, SHRP-P-338, 1993.

4. AASHTO Guide for Design of Pavement Structures, American Association of State Highway and Transportation Officials, 1993.

5. 2004 Traffic Data Report, Natchez Trace Parkway, Mississippi and Tennessee, National Park Service

APPENDIX A

SITE VICINITY MAP

BORING LOCATION PLANS

Scale Date

SITE LOCATION MAP

Natchez Trace Parkway Overlay, Sections 3H & 3J

Choctaw County, Mississippi 6/1/2010

Project Location

.5

B-181

P-1 N

O LD

P R

E U

C H

R O

A

D

C A

M P

N N

MS

SE

PRA-NATR 3H23, J10

REG

STATE

PROJECT

SHEET

NO.

TOTAL

SHEETS

NATCHEZ TRACE PARKWAY

U.S. DEPARTMENT OF TRANSPORTATION

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VIRGINIA

NOTES:

1. Plans were developed from Parkway’s Land-Use Plans and from as-builts. Stationing was wheel measured and painted along the right edge of pavement every 50 ft. with P-K nails placed every 500 ft.

3. Call Mississippi One Call System, Inc. at 1-800-227-6477 or 601-362-4374 or 811 prior to digging.

4. When installing new pavement markings, match existing markings and as directed by the CO. See Permanent Pavement Marking Summary and construction plans.

5. Potholes will be patched prior to initial lift.

CONSTRUCTION PLANS

7. Ensure positive drainage on all paved areas, once paving is complete. (0.5% min. slope)

8. Seed all disturbed areas outside of pavement, in accordance with section 625.

9. Re-establish a 6" curb reveal in all parking areas and all bridges.

10. Parkway width shown is not to scale.

2. See Bridge Paving Summary and Typical Sections for additional scope of work at bridges. Sawcut and seal construction joints at the bridges (See Detail E414-A).

Transition between milling depths and provide pavement overlay tie-ins to side roads in accordance with Detail E401.

6. See Detail E204-05 for side road connections.

BORING LOCATION PLANS

20 30

.5

B-182

N

M I

E R

L L

S

S

IN

G

O R

C

D01

MP 181 to 183

NATCHEZ TRACE PARKWAY

M A

T C

H L

I N

E M

P

M A

T C

H L

IN

E

M P

M P

M A

T C

H L

IN

E

M P

/0

M A

T C

H L

I N

E M

P

M P

FRENCH CAMP

PARKING AREA

Begin Project

MP 181, Sta. 0+00

See sheet # E01 for details

N

NATCHEZ TRACE PARKWAY

2" depth SACP overlay

2" depth SACP overlay

BRIDGE NO. 1Begin 2" depth

SACP overlay

APPENDIX B

SOIL TEST BORING RECORD KEY SHEET

SOIL TEST BORING LOGS

PAVEMENT CONDITION SURVEY FORMS

Clayey sands, sand - clay mixtures.

Boulders

GC

SW

No.200 No.40

(More than 50% of material is

SMALLER than No. 200 sieve size)

(More than 50% of coarse fraction is SMALLER than the No. 4 Sieve

Size)

Fine Medium Coarse Fine

RELATIVE DENSITY

OF SAND

Silty gravels, gravel - sand - silt mixtures.

SANDS

(More than 50% of coarse fraction is LARGER than the No. 4 sieve size)

GRAVELS

Well graded sands, gravelly sands, little or no fines.

Poorly graded sands or gravelly sands, little or no fines.

No Recovery

Dilatometer

MAJOR DIVISIONS GROUP

SYMBOLS

LEGEND FOR DRILLING METHODS

HSA

CFA

DC

RW

AWG

NQ

- Hollow Stem Auger

- Continuous Flight Auger

- Driving Casing

- Rotary Wash

- Rock Core, 1-1/8"

- Rock Core, 1-7/8"

HIGHLY ORGANIC SOILS

GW

GP

SILTS AND CLAYS

(Liquid limit LESS than 50)

(Liquid limit GREATER than 50)

COARSE

GRAINED

SOILS

(More than 50% of material is LARGER than No. 200 sieve size)

(Little or no fines)

Water Table after 24 hoursCLEAN

SANDS

(Little or no fines)

SANDS WITH

FINES

Pressure Meter

Packer

Consistency Very Soft Soft Firm Stiff Very Stiff Hard

0-1 2-4 5-8 9-15 15-30 Over 30

Shelby Tube (SH)

SP

SM

SC

ML

No.10 No.4 3/4" 3" 12"

CLEAN

GRAVELS

CONSISTENCY OF

COHESIVE SOILS

OL

MH

CH

OH

PT

TYPICAL NAMES

Well graded gravels, gravel - sand mixtures, little or no fines.

Crandall Sampler

Water Table at time of drilling

CL

BOUNDARY CLASSIFICATIONS: Soils possessing characteristics of two groups are designated by combinations of group symbols.

Coarse

Rock Core (RC)

Cobbles

WOH - Weight of Hammer

(Appreciable amount of fines)

SILT OR CLAY

SAND GRAVEL

U.S. STANDARD SIEVE SIZE

Reference: The Unified Soil Classification System, Corps of Engineers, U.S. Army Technical Memorandum No. 3-357, Vol. 1, March, 1953 (Revised April, 1960)

Clayey gravels, gravel - sand - clay mixtures.

FINE

GRAINED

SOILS

Poorly graded gravels or gravel - sand mixtures, little or no fines.

Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts and with slight plasticity.

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays.

Split Spoon Sample (SS)

Auger Cuttings

Bulk Sample

Organic silts and organic silty clays of low plasticity.

Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts.

Inorganic clays of high plasticity, fat clays

Organic clays of medium to high plasticity, organic silts.

Peat and other highly organic soils.

SILTS AND CLAYS

GM

KEY TO SYMBOLS AND

DESCRIPTIONS

GRAVELS

WITH FINES

(Appreciable amount of fines)

Silty sands, sand - silt mixtures

N-Value DensityN-Value 0-4 5-10 10-30 31-50 Over 50

Very Loose Loose Medium Dense Dense Very Dense

JDAAS

Stamp

SS-1

AU-2

SS-3

6" ASPHALT

2" Gravelly SAND BASE Silty SAND (SM), trace clay, gray to red-orange, moist, loose to medium dense.

Silty CLAY (CL), trace to little sand, orange-brown to gray, moist, stiff.

Boring terminated at 5 feet.

Boring backfilled with soil cuttings and asphalt patched after drilling.

7-8-10 (N = 18)

2-5-7 (N = 12)

Solid Stem AugerSimco 2800 HS

NM (%)

Hammer Type:

Method:

WSA Representative:

LL (%)

Project No.: 104271

Casing Diameter:

Station: 15+00 Offset: 6ft L

SOIL CLASSIFICATION

AND REMARKS

Dry

N-COUNT

Date Begun: 5/5/10

T Y P E

Sheet 1 of 1

RQD

% REC

PL (%)

D E P T H

(ft)

MRH Automatic

Project:

SAMPLES

Groundwater Levels (feet)

Not Measured

Casing Length:

SPT (bpf)

FINES (%)

0:

24:

Interpretations provided are based on the intervals sampled at the time of drilling. Actual conditions between sampling intervals may differ as a result of gradual or abrupt changes.

L E G E N D

10 20 30 40 50 60 70 80 90 100

Date Completed: 5/5/10

1s t 6

2n d 6"

3r d

6"

Equipment:

SEE KEY SYMBOL SHEET FOR EXPLANATION

OF SYMBOLS AND ABBREVIATIONS BELOW.

BORING NO. B-181

I D E N T

E L E V

(ft)

Natchez Trace Parkway, 3H & 3J

Location: Natchez Trace Parkway MP 181

W S

A L

O G

N

TP

.G P

J N

A

TC

H E

Z.

G

D T

/4

/1

SS-3

5.5" ASPHALT

2" Gravelly SAND BASE Silty SAND (SM), trace clay, gray to red-brown, moist, loose to medium dense.

Boring terminated at 5 feet.

Boring backfilled with soil cuttings and asphalt patched after drilling.

7-5-5 (N = 10)

2-2-5 (N = 7)

Solid Stem AugerSimco 2800 HS

NM (%)

Hammer Type:

Method:

WSA Representative:

LL (%)

Project No.: 104271

Casing Diameter:

Station: 5+00 Offset: 6ft R

SOIL CLASSIFICATION

AND REMARKS

Dry

N-COUNT

Date Begun: 5/5/10

T Y P E

Sheet 1 of 1

RQD

% REC

PL (%)

D E P T H

(ft)

MRH Automatic

Project:

SAMPLES

Groundwater Levels (feet)

Not Measured

Casing Length:

SPT (bpf)

FINES (%)

0:

24:

Interpretations provided are based on the intervals sampled at the time of drilling. Actual conditions between sampling intervals may differ as a result of gradual or abrupt changes.

L E G E N D

10 20 30 40 50 60 70 80 90 100

Date Completed: 5/5/10

1s t 6

2n d 6"

3r d

6"

Equipment:

SEE KEY SYMBOL SHEET FOR EXPLANATION

OF SYMBOLS AND ABBREVIATIONS BELOW.

BORING NO. B-182

I D E N T

E L E V

(ft)

Natchez Trace Parkway, 3H & 3J

Location: Natchez Trace Parkway MP 182

W S

A L

O G

N

TP

.G P

J N

A

TC

H E

Z.

G

D T

/4

SS-3

5" ASPHALT

2" Gravelly SAND BASE Silty SAND (SM), trace clay, red-brown to gray to yellow tan, moist, medium dense.

Lean CLAY (CL), trace to little sand, orange-brown to gray, moist, medium stiff to stiff.

Boring terminated at 5 feet.

Boring backfilled with soil cuttings and asphalt patched after drilling.

10-10-9 (N = 19)

4-6-8 (N = 14)

Solid Stem AugerSimco 2800 HS

NM (%)

Hammer Type:

Method:

WSA Representative:

LL (%)

Project No.: 104271

Casing Diameter:

Station: 5+00 Offset: 6ft L

SOIL CLASSIFICATION

AND REMARKS

Dry

N-COUNT

Date Begun: 5/5/10

T Y P E

Sheet 1 of 1

RQD

% REC

PL (%)

D E P T H

(ft)

MRH Automatic

Project:

SAMPLES

Groundwater Levels (feet)

Not Measured

Casing Length:

SPT (bpf)

FINES (%)

0:

24:

Interpretations provided are based on the intervals sampled at the time of drilling. Actual conditions between sampling intervals may differ as a result of gradual or abrupt changes.

L E G E N D

10 20 30 40 50 60 70 80 90 100

Date Completed: 5/5/10

1s t 6

2n d 6"

3r d

6"

Equipment:

SEE KEY SYMBOL SHEET FOR EXPLANATION

OF SYMBOLS AND ABBREVIATIONS BELOW.

BORING NO. B-183

I D E N T

E L E V

(ft)

Natchez Trace Parkway, 3H & 3J

Location: Natchez Trace Parkway MP 183

W S

A L

O G

N

TP

.G P

J N

A

TC

H E

Z.

G

D T

/4

SS-3

10.5" ASPHALT

2" Gravelly SAND BASE Silty SAND (SM), trace clay, red-brown to gray to yellow-tan, moist, medium dense.

Silty CLAY (CL), trace to little sand, orange-brown to gray, moist, medium stiff to stiff.

Boring terminated at 5 feet.

Boring backfilled with soil cuttings and asphalt patched after drilling.

8-13-13 (N = 26)

4-3-5 (N = 8)

Solid Stem AugerSimco 2800 HS

NM (%)

Hammer Type:

Method:

WSA Representative:

LL (%)

Project No.: 104271

Casing Diameter:

Station: 5+00 Offset: 6ft R

SOIL CLASSIFICATION

AND REMARKS

Dry

N-COUNT

Date Begun: 5/5/10

T Y P E

Sheet 1 of 1

RQD

% REC

PL (%)

D E P T H

(ft)

MRH Automatic

Project:

SAMPLES

Groundwater Levels (feet)

Not Measured

Casing Length:

SPT (bpf)

FINES (%)

0:

24:

Interpretations provided are based on the intervals sampled at the time of drilling. Actual conditions between sampling intervals may differ as a result of gradual or abrupt changes.

L E G E N D

10 20 30 40 50 60 70 80 90 100

Date Completed: 5/5/10

1s t 6

2n d 6"

3r d

6"

Equipment:

SEE KEY SYMBOL SHEET FOR EXPLANATION

OF SYMBOLS AND ABBREVIATIONS BELOW.

BORING NO. B-184

I D E N T

E L E V

(ft)

Natchez Trace Parkway, 3H & 3J

Location: Natchez Trace Parkway MP 184

W S

A L

O G

N

TP

.G P

J N

A

TC

H E

Z.

G

D T

/4

SS-3

5" ASPHALT

2" Gravelly SAND BASE Silty SAND (SM), red-brown, moist, medium dense.

Clayey SAND (SC), red-brown to gray, moist.

Lean CLAY (CL), trace to little sand, gray to orange-brown, moist, stiff.

Boring terminated at 5 feet.

Boring backfilled with soil cuttings and asphalt patched after drilling.

9-10-10 (N = 20)

3-3-6 (N = 9)

Solid Stem AugerSimco 2800 HS

NM (%)

Hammer Type:

Method:

WSA Representative:

LL (%)

Project No.: 104271

Casing Diameter:

Station: 5+00 Offset: 6ft L

SOIL CLASSIFICATION

AND REMARKS

Dry

N-COUNT

Date Begun: 5/5/10

T Y P E

Sheet 1 of 1

RQD

% REC

PL (%)

D E P T H

(ft)

MRH Automatic

Project:

SAMPLES

Groundwater Levels (feet)

Not Measured

Casing Length:

SPT (bpf)

FINES (%)

0:

24:

Interpretations provided are based on the intervals sampled at the time of drilling. Actual conditions between sampling intervals may differ as a result of gradual or abrupt changes.

L E G E N D

10 20 30 40 50 60 70 80 90 100

Date Completed: 5/5/10

1s t 6

2n d 6"

3r d

6"

Equipment:

SEE KEY SYMBOL SHEET FOR EXPLANATION

OF SYMBOLS AND ABBREVIATIONS BELOW.

BORING NO. B-185

I D E N T

E L E V

(ft)

Natchez Trace Parkway, 3H & 3J

Location: Natchez Trace Parkway MP 185

W S

A L

O G

N

TP

.G P

J N

A

TC

H E

Z.

G

D T

/4

SS-3

5" ASPHALT

2" GRANULAR BASE

Silty SAND (SM), red-brown, moist, medium dense.

Sandy lean CLAY (CL), gray to orange, moist, stiff.

Boring terminated at 5 feet.

Boring backfilled with…