1. General Furnish a 15,000-gallon underground HDPE water storage tank for the collection and reuse of water from pit dewatering processes. The tank shall be manufactured for long-term below-ground installation, resistant to corrosion, chemicals, and biological growth, and shall include all specified graywater-specific fittings and components. Installation to be performed in accordance with the manufacturer’s written instructions. 2. Acceptable Product • Manufacturer: Norwesco, Inc. • Model: N-41615 – 15,000-Gallon Underground Water Tank • Or Approved Equal: Alternative products must meet or exceed these specifications and be pre-approved by the design engineer. 3. Tank Construction • Material: High-Density Polyethylene (HDPE), rotationally molded, single-piece seamless design • Capacity: 15,000 U.S. gallons • Dimensions (approx.): 511" L x 101" W x 107" H • Weight: Approx. 3,800 lbs. • Color: Black or green • Manways: Minimum of Two (2) 22" or larger gasketed lids • Risers: Minimum of Two (2) 22" x 36" or larger HDPE risers with watertight extensions to within 6" of grade • Design Life: Minimum 30 years buried • Load Rating: Non-traffic-rated (pedestrian or landscaped areas only) 4. Required Graywater Fittings and Accessories A. Inlet and Outlet • (1) 4" Schedule 80 PVC or HDPE bulkhead fitting (inlet – top third of tank) • (1) 4" Schedule 80 PVC or HDPE bulkhead fitting (outlet – bottom third of tank or sump) • (1) 2" bulkhead drain fitting with threaded plug or valve • (1) 2" overflow fitting with screened end and backflow prevention B. Venting • (1) 2" screened vent fitting • Vent to terminate above grade per code with insect-proof cover and protection from flooding C. Access & Monitoring • Minimum of (2) Two 22" access ports with gasketed, bolted lids • Minimum of (2) Two 22" x 36" HDPE risers, stackable, watertight
