A04_SOW__Replace_Septic_System_at_Ft_Raleigh_Maintenance.doc

CAPE HATTERAS NATIONAL SEASHORE

Fort Raleigh Manteo, North Carolina

STATEMENT OF WORK:

Replace the Septic Tank and Drainfield at the

Ft Raleigh Maintenance Building

NATIONAL PARK SERVICE

Region 2

CAPE HATTERAS NATIONAL SEASHORE

Outer Banks Group

Statement of Work Replace Septic Tank and Drainfield at Ft Raleigh Maintenance Building

1.0 INTRODUCTION

The National Park Service (NPS) Cape Hatteras National Seashore (CAHA) has a requirement to replace the septic tank and drainfield serving the Maintenance Building on Fort Raleigh National Historic Site (FORA).

2.0 CONSTRUCTION SITE LOCATION

The address for the project site is 1423 Pear Pad Rd Manteo, NC 29754.

3.0 BACKGROUND AND EXISTING CONDITIONS

The Maintenance Building at 1423 Pear Pad Rd in Manteo, NC is a CMU constructed shop and storage facility for the Outer Banks Group. The building is a CMU Block structure approximately 40 ft x 64 ft. A chain link fence surrounds the maintenance compound. The building includes a restroom with one sink and toilet, and a break room with a sink and floor drain which lead to a septic tank and drainfield located behind the building. There are 4 employees who utilize the Maintenance Building on a daily basis. The wastewater producing fixtures in the Ft Raleigh Maintenance include one toilet, one sink, one urinal, one breakroom sink, and an ice machine drain. Wastewater drains under the parking area to the west of the building to a septic tank which measures approximately 2 ft wide x 10 ft long x 4 – 5 ft deep, or approximately 500 – 750 gallons. The septic tank is approximately 20 ft from a fenceline surrounding the property. The drainfield is oriented 90 degrees from the septic tank running beside the fenceline.

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.

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 drainfield and septic tank located behind Ft Raleigh Maintenance Building.

4.0 SCOPE OF WORK

Replace the septic system with a new septic system.

1. Demo existing concrete septic tank approx. 750 gal.

2. Demo existing drainfield components:

a. Remove existing drainfield pipe and distribution box (approx. 90 linear ft)

b. Remove approximately 30 ft of existing drain pipe from the septic tank back towards the maintenance building.

c. Backfill the excavated area for the old tank and trenches with soil from new excavations.

3. Provide new precast concrete septic tank: minimum size 750 gallons and maximum size 1,000 gallons. Locate new tank on the west side of the Ft Raleigh Maintenance building in the location shown in figure 3 below, approximately 60 ft from the maintenance building. (See below sketch and attached drawings of proposed layout of new drainfield).

a. Connect the existing drain line from the maintenance building to the new septic tank. Use schedule 40 PVC or approved equal material.

b. 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.

4. The new septic tank 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.

5. Provide new distribution tank and infiltrator type drainfield. Drainfield shall be a minimum of 64 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. Replace unsuitable soil with new suitable soil.

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 or Standard profile for 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.

6. 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.

Figure 3: Proposed layout of new Septic System at Ft Raleigh Maintenance

NOTES:

1. The Contractor must verify existing conditions and above and below ground mark utilities 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.

5.0 GOVERNMENT FURNISHED PROPERTY

1. No Government property, materials, or equipment will be provided. Water and electricity on the exterior of the existing MRC 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 Drain Field Infiltrator product data

3.3 Manhole/Riser data

3.4 Seed Mix

Replace Septic Tank and Drainfield at Ft Raleigh MRC