A04_SOW__Replace_Septic_Systems_at_Bodie_Island_Dune_Town.doc

CAPE HATTERAS NATIONAL SEASHORE

Fort Raleigh Manteo, North Carolina

STATEMENT OF WORK:

Replace Septic Tanks and Drainfields at Bodie Island Dunetown

NATIONAL PARK SERVICE

Region 2

CAPE HATTERAS NATIONAL SEASHORE

Outer Banks Group

Statement of Work Replace Septic Tanks and Drainfields at Bodie Island Dunetown

1.0 INTRODUCTION

The National Park Service (NPS) Cape Hatteras National Seashore (CAHA) has a requirement to replace two septic tanks and drainfields at the Bodie Island Dunetown area.

2.0 CONSTRUCTION SITE LOCATION

The address for the project site is 506 Park Service Rd Nags Head, NC 27959.

3.0 BACKGROUND AND EXISTING CONDITIONS

Bodie Island (BI) Dunetown is located at the end of Park Service Rd in Nags Head, past the BI Maintenance complex and four housing units. Park Service Rd provides access to 8 concrete pads with unpaved driveways suitable for long term use by recreational vehicles. Each site includes hook ups for water, septic, and electrical service. The septic connections route sewage to septic tanks and drainfields. Figure 1 below shows the existing layout of the RV Pads at BI Dunetown. The existing tanks are approximately 2,000 gallons each. The septic drain lines within the drainfields were scoped to find the location and directon of the underground piping. Some of the septic drainlines have collapsed. Approximate location is marked on site by flags. The existing ground is soft sand, well draining, and easily excavated. Existing water, sewer, and electric lines are installed at varying depths from just below the surface to approx 24 inches below grade. Some existing septic lines are close to the surface to provide proper slope for drainage and limit the ability to drive vehicles around the site off of the existing pavement.

The site was examined according to North Carolina Administrative Code Title 15A Chapter 18 Environmental Health Subchapter 18A Sanitation Section .1900 Sewage Treatment and Disposal Systems. Specifically, the topography, landscape, soil characteristics, soil wetness condition and water table depth, soil depth and restrictive horizons, daily flow rate, and setbacks for the location of tank and drainfield. Soil wetness was found approximately 36 inches below ground, however standing water was not found until greater than approximately 48 inches below ground.

Consultation with the Dare County Public Health On Site Water Protection Branch provided helpful information on the soil type in the Ft Raleigh area as a Sandy Loam. A percolation test was not conducted on site due to the sandy nature of the soil. A maximum Long Term Acceptance Rate of 0.8 is allowable for the drainfield sizing calculations, depending on the type of drainfield installed.

Figure 1: Existing septic tanks and drainfields at Bodie Island Dunetown

4.0 SCOPE OF WORK

Replace the septic systems with a new septic system.

1. Task 1: Submit product data for the proposed septic system components

2. Task 2: Locate existing utilities for the septic systems and existing utilities to remain within the Limits of construction.

3. Task 3: Demo existing Septic System 1.

a. Utilize Site 203 to access Septic 1 (See Figure 2 below). Do not cross over existing utilities to remain with heavy equipment or vehicles which could damage the utilities. Minimize crossing over utility lines which must be crossed to perform demolition and new construction. Utilize spreader boards at ground level to drive over utility lines/pipes with less than 18” cover.

b. Demo concrete septic tank, approx. 2,000 gal. and distribution box

c. Cut and protect existing drainline leading into the existing tank for reconnection to new tank.

4. Task 4: Demo existing drainfield components:

a. Remove existing drainfield pipe (approx. 150 linear ft), to include collapsed / broken / clogged lines.

5. Task 5: Provide new precast concrete septic tank: 2,000 gallons.

a. Locate new tank in same location as the existing tank. (See below sketch and attached drawings of proposed layout of new drainfield). Ensure the new tank is set at proper depth to allow proper slope of the reconnection of the existing drainline into the new tank.

b. Reconnect the existing drain line serving the RV sites to the new septic tank. Use schedule 40 PVC or approved equal material.

c. Provide properly sealed joints and connections from the existing drain pipes. to new sections of pipe which seal to the new septic tank. Use schedule 40 PVC or approved equal material which meet the International Plumbing Code Chapter 7 for sanitary drainage.

6. Task 6: Provide new distribution box and infiltrator type drainfield. Drainfield for Septic System 1 shall be a minimum of 150 LF of new drain lines.

a. Remove roots within the drainfield trench footprint. Roots larger than 1 inch in diameter shall be pulled back to 5 ft away from the trench and cut and removed.

b. Remove unsuitable soil from new trenches (approximately 10 cy). Unsuitable soil may be reused to backfill existing tank excavation, or spread on site to smooth out ruts. Replace unsuitable soil with new suitable soil within the drainfield trenches.

c. Provide 36 in wide infiltrator type septic drainfield sections similar to Infiltrator Water Technologies Quick4 Equalizer 36 which provide a minimum overall length of 150 LF of infiltration drain lines. Low profile infiltration sections with lower capacity are not acceptable.

d. Install chambers according to manufacturer’s installation instructions. Provide filter cloth above infiltrator sections according to the manufacturer’s instructions for the brand name utilized.

7. Task 7: Demo existing Septic System 2.

a. Utilize Site 209 to access Septic 2 (see Figure 2 below). Do not cross over existing utilities to remain with heavy equipment or vehicles which could damage the utilities. Minimize crossing over utility lines which must be crossed to perform demolition and new construction. Utilize spreader boards at ground level to drive over utility lines/pipes with less than 18” cover.

b. Demo concrete septic tank, approx. 2,000 gal. and distribution box

c. Cut and protect existing drainline leading into the existing tank for reconnection to new tank.

8. Task 8: Demo existing drainfield components:

a. Remove existing drainfield pipe (approx. 205 linear ft), to include collapsed / broken / clogged lines.

9. Task 9: Provide new precast concrete septic tank: 2,500 gallons.

a. Locate new tank in same location as the existing tank. (See below sketch and attached drawings of proposed layout of new drainfield). Ensure the new tank is set at proper depth to allow proper slope of the reconnection of the existing drainline into the new tank.

b. Reconnect the existing drain line serving the RV sites to the new septic tank. Use schedule 40 PVC or approved equal material.

c. Provide properly sealed joints and connections from the existing drain pipes. to new sections of pipe which seal to the new septic tank. Use schedule 40 PVC or approved equal material which meet the International Plumbing Code Chapter 7 for sanitary drainage.

10. Task 10: Provide new distribution tank and infiltrator type drainfield. Drainfield for Septic System 2 shall be a minimum of 260 LF of new drain lines.

a. Remove roots within the drainfield trench footprint. Roots larger than 1 inch in diameter shall be pulled back to 5 ft away from the trench and cut and removed.

b. Remove unsuitable soil from new trenches (approximately 10 cy). Unsuitable soil may be reused to backfill existing tank excavation, or spread on site to smooth out ruts. Replace unsuitable soil with new suitable soil within the drainfield trenches.

c. Provide 36 in wide infiltrator type septic drainfield sections similar to Infiltrator Water Technologies Quick4 Equalizer 36 which provide a minimum overall length of 150 LF of infiltration drain lines. Low profile infiltration sections with lower capacity is not acceptable.

d. Install chambers according to manufacturer’s installation instructions. Provide filter cloth above infiltrator sections according to the manufacturer’s instructions for the brand name utilized.

11. Task 11: Provide seeding to the disturbed area, including demolished drainfield, new drainfield, and ruts or other disturbance created by construction. Continue to water the grass until 75% of the area has seeded and growing.

a. Seed shall be suitable for the following:

i. Mostly sun location

ii. Residential lawn

iii. Mowing operations with hand operated push or riding mowers

iv. Sandy soils

v. Septic Field coverage (roots that do not grow deeper than 24 inches)

vi. No weeds (dandelion, bahai, pennywort)

vii. No exotic species.

b. Broadcast or Hydroseed. Add a cover crop of grain rye at 30 lbs/acre. Rake broadcasted seed mix into the soil and saturate with water 2 – 3 times per day for 7 days, or until 75% of the area has seeds germinated and growing at least 1 inch high. Hydroseeded area may be observed for 7 days or until 75% of the area has growing seeds. If after 7 days, the area is less than 75% covered with new growth, overseed again and water 2-3 times per day until 75% of the ground is covered with growth.

12. The new septic tanks shall be from a State approved septic tank manufacturer and include at a minimum:

a. Water tight joints

b. Concrete baffles

c. Effluent filter

d. Access opening less than 18 inches from the end of the tank to visually see the inflow pipe.

e. Adequate opening less than 12 inches from the effluent filter to be able to visually see and physically reach the effluent filter without entering the tank.

f. Access opening to visually see the concrete baffle.

g. Provide Concrete lids on the concrete septic tank with type 316 stainless steel handles.

h. HDPE risers and riser lids which extend a minimum of 12 inches above grade. Plastic riser lids shall be locking, mechanically sealed, or above 65 lbs in weight.

Figure 2: Access routes for Septic Systems.

NOTES:

1. The Contractor must verify existing conditions and above and below ground and mark utilities within the limits of construction prior to digging.

2. The Contractor must track demolition debris which are removed/recycled and provide NPS with receipts showing the weight and volume and type of material removed/recycled as part of this project.

3. No construction debris will be allowed to be left on premises. All public areas will remain clean and passible during normal business hours. During business hours, the contractor will ensure that no music is playing in the work areas and no foul language will be tolerated during or after business hours. Work on this project will be accomplished within the hours of 7:00 AM to 5:00 PM Monday thru Friday.

4. Due to the limited cover above some septic lines, vehicles must be kept to paved surfaces. Parking and driving of vehicles and equipment must be kept to areas without underground utility lines, valves, tanks, etc. which may be damaged.

5.0 GOVERNMENT FURNISHED PROPERTY

1. No Government property, materials, or equipment will be provided. Water and electricity at an empty RV site is available for Contractor use during this project. Contractor is responsible for lockout/tagout. Contractor is responsible for cleaning up site daily, and for repairing ruts created in grass areas. Ruts shall be filled in or raked smooth before final acceptance of the project.

6.0 SUBMITTALS

1. Work schedule: delineating the various stages of work by phase (milestones) prior to the preconstruction conference.

2. Safety Plan/Accident Prevention Plan prior to the preconstruction conference.

3. Product Samples. The Contractor shall submit written documentation or color/product samples for materials identified in the Scope of Work for selection by the CO/COR.

3.1 Septic Tank product data

3.2 Septic Drainfield Infiltrator product data

3.3 Manhole/Riser data

3.4 Seed Mix

Replace Septic Tanks and Drainfields at Bodie Island Dune Town