Soils and Foundation Report.pdf

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Federal Highway Administration

Eastern Federal Lands Highway

Division

Soils and Foundation Report –

Addendum 2

Pavement Analysis

Investigation

Rehabilitation of Park Roads for

Blue Ridge Parkway

Yancey and Buncombe Counties, NC

PRA-BLR1 2P14

Contract No. DTFH71-02-D-00004

Task Order 0003

Soils and Foundation Report – Addendum 2

Pavement Analysis Investigation

Rehabilitation of Park Roads for Blue Ridge Parkway Yancy and Buncombe Counties, North Carolina

Prepared for:

Federal Highway Administration

Eastern Federal Lands Highway Division

Prepared by:

ARCADIS

1210 Premier Drive

Suite 200

Chattanooga

Tennessee 37421

Tel 423.756.7193

Fax 423.756.7197

Our Ref.:

CT052885.0014

Date:

June 2008

This document is intended only for the use of the individual or entity for which it was prepared and may contain information that is privileged, confidential and exempt from disclosure under applicable law. Any dissemination, distribution or copying of this document is strictly prohibited.

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Table of Contents

Background 1

FDR Pavement Sections 2

Mainline Parkway 3

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Soils and Foundation

Report – Addendum 2

Blue Ridge Parkway Rehabilitation

Background

The Blue Ridge Parkway is a 469-mile scenic corridor that connects Shenandoah

Valley in Virginia to the Great Smoky Mountains National Park in North Carolina.

Adjacent to the parkway, which ranges in elevation from 649 feet to 6,047 feet, are recreational areas that include picnic facilities, hiking trails, visitor centers, overlooks, and campgrounds. The Blue Ridge Parkway, conceived as a Depression-relief project in the 1930s, took more than 50 years to construct.

The pavement along Blue Ridge Parkway and adjacent access roads and pull-offs is in various stages of deterioration and in need of rehabilitation. Area features such as asphalt paths, granite curbs, rubble and masonry walls and steps are also in need of repair. Under initial Task Order No. 0003, ARCADIS was authorized to investigate

Section 2P14 of the Blue Ridge Parkway and develop plans and specifications to rehabilitate this section of the parkway. Section 2P14 consists of the rehabilitation of the parkway pavement between Milepost 359.8 at the Balsam Gap Overlook and

Milepost 375.3. Also included is the reconstruction, replacement, or rehabilitation of ditches, pipes, walls, sidewalks, and curbs. A soils and foundation report has been previously submitted documenting results of subsurface and pavement investigations along Section 2P14.

Modification Nos. 0006 and 0007 to the Task Order were later issued to cover the investigation and evaluation of alternative pavement rehabilitation techniques. Full

Depth Reclamation (FDR) was determined to be the best alternative to rehabilitate the above referenced roadway. This rehabilitation process would reduce and/or eliminate the amount of excess asphalt material that would be required to be “hauled off site” and disposed. The FDR process would also minimize the net change in pavement surface elevations that are very critical along this roadway.

Full Depth Reclamation

Full Depth Reclamation (FDR) is a rehabilitation technique that uniformly pulverizes and blends the existing asphalt pavement layer, base, subbase and/or subgrade soils to produce a homogeneous base material. The FDR process generally treats and improves 6 in. to 12 in. of the existing pavement structure. The FDR process is performed without heat (similar to cold mix recycling).

The FDR process generally consists of pulverizing the existing pavement materials, adding additional aggregates (if necessary), adding stabilizing additive, mixing, g:\wp\ct052885\rpt\soils-foundationreport-addendum2\blueridgeparkwayrehabilitation-addendum2.doc 2 shaping, compaction, final shaping and placing an asphalt wearing surface. The stabilizing agents generally consist of either Portland cement, lime, fly ash or asphalt emulsion which are used to enhance the mechanical properties and structural strength of the reclaimed base materials. The FDR construction process generally utilizes common roadway construction equipment (i.e., reclaimer or pulverizer, stabilizing additive unit, motor grader and rollers).

Full depth reclamation is an innovative and cost-effective method of rehabilitating and/or reconstructing highly distressed or failed asphalt pavements. This rehabilitation process is best suited for pavements that have reached conditions that are no longer economical to maintain with common maintenance procedures.

Some of the advantages of the FDR process are listed below:

Reuses existing pavement materials

Eliminates asphalt layer distresses (i.e., cracking, rutting, potholes)

Corrects base failures

Reshapes surface profile

Improves surface drainage

Increases structural capacity

Reduces traffic disruptions during construction

FDR Pavement Sections

The FDR rehabilitation process is recommended as an alternative to reconstructing the highly distressed or failed areas along the referenced section of the Blue Ridge

Parkway near Asheville, North Carolina.

Based on the pavement design analysis presented in the Soils and Foundation Report prepared by ARCADIS dated September 2006, the following alternative structural pavement sections developed by Burns Cooley Dennis, Inc., for the Mainline Parkway and the parking areas are provided:

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Mainline Parkway

The station ranges for the Mainline Parkway are as follows:

366/24+10 to 368/20+00

370/2+00 to 374/20+37

374/30+01 to 375 04+56

These areas will receive the following applications:

• 3 inches of asphalt surface course (two 1.5-inch layers)

• 10 inches of FDR Portland cement-treated base (minimum 300 psi, 7-day compressive strength, minimum of 4% Portland cement by total dry mix)

• Design Structural Number (SN): 2.8

Parking Areas

The parking areas include the following:

Craggy Dome

Craggy Garden Visitor Center

Craggy Garden Picnic Area

These areas will receive the following applications:

• 3 inches of asphalt surface course (two 1.5-inch layers)

• 6 inches of FDR Portland cement-treated base (minimum 300 psi, 7-day unconfined compressive strength, minimum of 4% Portland cement by total dry mix)

• Design Structural Number (SN): 2.2

Determine 7-day unconfined compressive strength per ASTM D 1633, Method A.

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The above pavement structures meet or exceed the structural capacity of the reconstructed asphalt pavement sections presented in the original Soils and

Foundation Report for this project.