SOW_Const_Pkg_at_Former_BI_USCG_Station.pdf

Construct Parking Area At Former Coast Guard Entrance on Bodie Island Page 1

CAPE HATTERAS NATIONAL SEASHORE

Outer Banks Group

Statement of Work

Construct Parking Area at the Former Coast Guard Station Entrance on Bodie

Island

1.0 INTRODUCTION

The National Park Service (NPS) Cape Hatteras National Seashore (CAHA) has a requirement to build a new parking area on Bodie Island at an existing paved entrance where a Coast Guard

Station once existed.

2.0 CONSTRUCTION SITE LOCATION

The Old US Coast Guard Station on Bodie Island was located approximately ½ mile north of

Lighthouse Bay Dr on Bodie Island and 5.3 miles south of Whalebone Intersection in Nags

Head.

3.0 BACKGROUND AND EXISTING CONDITIONS

The paved entrance to an old site is still in use by park visitors. The site is generally flat and includes a paved entrance lane approximately 30 ft wide by 110 ft long. The pavement widens slightly toward the end to approximately 36 ft wide and totals approximately 3,900 sf of asphalt surface. The pavement transitions to a sand surface that continues until the grasses and sand dunes are reached. Social trails lead through the sand and beach grass over the sand dunes to the

Atlantic Ocean.

A Century Link fiber optic / communications cable runs along the north side of the paved area and runs from north to south across the sandy area between the end of the pavement and the sand dunes.

The NPS completed an Environmental Assessment (EA) in June 2013 which included this site on

Hatteras Island. The EA provides a map of the boundary which marks the extents of the area which can be disturbed for a new parking area, shown in Figure 1. The NPS has placed several flags to mark wetlands areas and boundary available for disturbance.

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Figure 1: Location of existing paved entrance for new parking area.

Figure 2: Street view of existing paved entrance to the former Coast Guard Station

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4.0 STATEMENT OF WORK

1. Task 1: Overlay the existing paved entrance to the parking area.

1.1. Overlay the existing 30 ft wide by 110 ft long paved entrance, connecting the new parking area to HWY 12, approximately 3,900 sf.

1.1.1. Prepare the existing pavement by sweeping/grading the debris/sand/vegetation from the existing pavement. Remove soil and grass from cracks in the pavement.

Pressure wash and/or airblow the cracks in the pavement to remove loose debris.

Crack and Seal the Lateral/Transverse Cracks. Repair missing and spalled asphalt to level the existing surface.

1.1.2. The new overlay shall be 2 inches of bituminous concrete asphalt, meeting

NCDOT Superpave S9.5B Surface Course to the edge of the existing pavement.

1.2. The newly overlayed paved entrance shall not be sloped to drain water onto Highway 12 and shall not result in a puddle at the intersection to Highway 12. Ensure drainage from new pavement into the ditches/turf areas adjacent to the new pavement and parking area.

1.3. Provide a painted stop bar 20 ft from the edge of Highway 12. New stop bar shall be 12 inches wide and 12 ft long on the outbound lane of the paved entrance. Provide double yellow lines at the center of the overlayed entrance for 25 ft connecting to the stop bar.

New double yellow lines shall be yellow traffic paint. Each line shall be 4 inches wide and the two parallel lines shall be 4 inches apart. New lines shall be painted in a single straight pass with enough paint thickness to completely cover the newly paved surface according to MUTCD installation standards. No markings are required inside the parking area to designate parking stalls.

2. Task 2: Construct an addition to the paved area to provide room for a minimum 10 Car parking area. Provide an area according to Figure 3 and Figure 4 below, approximately

4,100 sf of new clay and shell surface. The limits of construction must be within the area marked with flags onsite. The disturbance shall be kept to the minimum to complete the project. The disturbance shall not encroach upon wetlands. Underground Utility Marking of the existing cables is the responsibility of the contractor.

2.1. Clear and grub the site and excavate to remove vegetation and reach subgrade. Remove or mulch/chip vegetation and spread on site around the perimeter of the parking area within the established boundary. Excavate approximately 6 inches below ground to prepare for clay and shell. Excavated topsoil may be spread within the boundaries.

Clean sand free of vegetation and roots may be used as backfill material to level the site.

Topsoil with roots greater than 3/4 inch in diameter shall be mulched prior to spreading on site.

2.2. The new parking area shall be a clay and clam shell mixture according to the Material

Specification listed below. The surface of the parking area will be shells.

2.3. The parking area shall comprise of a 23 ft x 113 ft area on the south side of the existing paved entrance, and approximately 43 ft x 35 ft area on the east side of the existing paved area. The exact dimensions of the 43 ft x 35 ft area shall be adjust 1-2 ft in either direction to avoid the Century Link communications pedestal and communications cable.

Total new area shall be approximately 4,100 sf. No curb or edging required around the perimeter of the parking area.

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2.4. The clay and shell mix must be 10 inches thick minimum. The clay mixture must be placed and compacted to 90% standard proctor tests. The clay base layer must be a minimum of 4-8 inches thick to provide adequate drainage for the final surface. The final shell surface must be a minimum of 6 inches and maximum of 12 inches above grade and provide a minimum of 1:50 slope and maximum of 1:20 slope toward the south. Side slopes of the shoulder area to tie into existing grade shall be 3H:1V.

3. Task 3: Provide and install wood posts along the south and east perimeter the parking area and entrance, approximately 30 posts.

3.1. Install wood posts to mark the perimeter of the parking area. The wood posts must be new 6 in x 6 in square posts spaced 6 ft apart, with a minimum 2’-6” embedment and 3’-

6” exposed above grade. The posts must be pressure treated for ground contact according to the American Wood Preservation Association (AWPA) U1 standard. The posts shall extend around the south and east perimeter of the new shell parking area.

3.2. Chamfer the tops of the posts 1 inch on all 4 sides. Coat the exposed portion at the tops of the posts with Copper Naphthenate (8% minimum concentration) wood treatment.

Top coating must completely cover the top and cut portions of the posts.

3.3. Install 1.5 inch diameter poly-manila nylon rope through the posts. Drill holes through the posts approximately 5 inches from the top of the posts. Rope must be a continuous run through the posts. Knot, tape and burn both ends of the rope to keep the ends from fraying.

3.4. Secure the rope in place at each post using 3.5 inch type 316 stainless steel screws.

4. Task 4: Plant grass around the outside of the new shell surface parking area in disturbed areas.

4.1. Seed the disturbed areas surrounding the new parking area and paved entrance with

100% rye grass. Water/maintain the new seeded areas until at least 75% of the ground is established and growing.

4.2. Erosion controls such as silt fence, temporary seeding, etc., shall follow the State of

North Carolina Best Management Practices and must be shown on the layout. Silt Fence must be installed by hand. Temporary seed shall consist of 100% rye grass.

NOTES:

1. The Contractor shall notify NCDOT at least 7 days before mobilizing to the site.

Sand, Clay, and Shell Specifications:

Material Requirements:

1. The clay soil mixture must meet the following specifications:

a. The clay mix must be obtained from a source considered local to the Outer Banks.

Local material is considered to be material having a zero content of invasive species of plants, or any organic material. Top soil will not be accepted.

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Unsuitable material will be rejected and returned to the vendor at the vendor’s expense and will not be dumped on site.

b. The clay mix will be a product referred to as sandy loam and have an overall gradation of the following: 55-79 percent sand; 5-20 percent silt; and 12-20 percent clay.

c. Percentages of the listed soil contents may vary by plus or minus 2-3 percent.

d. The vendor supplying the clay mix is responsible for obtaining test results of the content of the material. The soil analysis must show the particle distribution including at a minimum:

i. Sieve size

ii. Percent passing each sieve

iii. Total percent gravel/coarse grains

iv. Total percent sand

v. Total percent silt

vi. Total percent clay

vii. Soil group classification

2. The clam shells must meet the following specifications:

a. The clam shells must be crushed and rolled to reduce edges. Whole shells should not account for more than 25% of the delivered material.

b. Scallops, cockle shells, whelks, and cone shells can be included but should not be more than 10% of the total shell volume.

c. Oyster shells may not be substituted.

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Figure 3: New Parking area at Former Coast Guard Station

Figure 4: Close up of new parking area and 6x6 posts