30 Cubic Yard ADS Roll-Off Dewatering Unit

US Patent Number 6,364,122

Dewatering unit shall be capable of holding a maximum of 30 cubic yards of dewatered solids when full, independent of filter media.  Dewatering unit shall be open topped with a rounded bottom and constructed with a minimum of A-36 carbon steel or equivalent.

Dewatering unit dimensions (including bracing) shall be a minimum Length 23′ 1″, minimum Width 8′ 6″; Height 5′ 11″ from ground level to top of unit.  Total height of the unit will include an additional 18″ for tarp bows.

Dewatering unit shall be constructed such that it is portable and can be hauled with a standard capacity roll-off truck.

Dewatering unit shall be equipped with a side-hinged, watertight, EPDM gasketed rear door with four (4) ratchet binders — one (1) on each side and two (2) in the middle of the door.

Dewatering unit shall include six (6) 4″ drain ports with NPT female threaded ends — three (3) mounted equidistance on each side.  Center of each drain port shall be positioned level with floor of the unit to ensure complete draining of the unit.  Drain ports shall include camlock fittings (with caps & chains) capable of connecting to 3″ diameter hoses.

Two (2) 3″ drain ports with NPT female threaded ends shall be mounted on the rear door, flush with door bottom, and shall include camlock fittings (with caps & chains) capable of connecting to 3″ diameter hoses.

Two (2) 3″ inlet ports with NPT female threaded ends shall be mounted at top of hinged door, and shall include camlock fittings (with caps & chains) capable of connecting to 3″ diameter hoses.

Materials of construction for dewatering unit shall be as follows:

  • Floor Plate —  1/4″ plate
  • Sides Plate —  7 gauge
  • Front Plate —  7 gauge
  • Front Post —  8 x 3 x 7 gauge formed channel
  • Side Post —  17 x 3 x 10 gauge formed channel
  • Latch Post —  6 x 3 x 7 gauge formed channel
  • Hinge Post —  17 x 3 x 7 gauge formed channel
  • Crossmembers — 3″ structural channel, 16″ o.c.
  • Top Rails —  4 x 3 x 3/16 structural tubing
  • Door Sheet —  7 gauge
  • Door Frame —  4 x 3 x 3/16 structural tubing
  • Inside Door Frame —  4 x 3 x 7 gauge formed channel
  • Rollers —  8″ diameter x 10″ long at rear, 8″ diameter x 8″ long at front
  • Rails —  6 x 2 x 1/4 structural tubing
  • Rail Extensions —  1  7/16 plate
  • Hook —  1  1/4 plate  36,000 psi minimum yield strength
  • Hook Plate —  3/4″ plate
  • Welds — interior continuous, exterior skip-welded
  • Finish —  Primed inside and out with a 2-part epoxy; top coated with a polyurethane finish

Top of center dividing wall shall be 3″ lower than outer walls of unit so liquid material can overflow the dividing wall without overflowing the sides of the dewatering unit.  The dividing wall shall be fixed onto the front wall & floor of the dewatering unit with no auxiliary bracing.

There shall be a 1  1/2″ space between the center dividing wall and the hinged rear door to allow for equalization of liquid levels as they are being pumped into the unit.

All metal structures within the unit interior shall be not less than 3/16″ thick with the exception of filter media backing material which shall be 3/4 #9 hot dipped galvanized expanded metal.

Interior sidewalls and floor shall be covered with a filter media sized appropriately to retain flocculated solids while filtered water is allowed to pass through and be collected in a common collection chamber, then discharged from the drain ports.

Filter media shall be installed on six (6) sides, covering a minimum 410 square feet of interior walls and floor, including both sides of center dividing wall.

Standard filter media (i.e. for septage, trap grease, municipal sludge) shall be a monofilament modified satin polyester filter material having a 437 CFM, Tensile Strength of 1890 LB/IN², particulate retention of 330 microns and shall include a 5 year warranty for normal wear and tear.

Filter media shall be installed to 3/4 #9 hot dipped galvanized expanded metal using stainless steel button head bolts and stainless steel acorn nuts.  All filter media shall be mounted flush and tensioned properly. 

Dewatering unit shall include one (1) side to side roll-over tarp of not less than 22 oz. vinyl coated nylon material with five (5) removable galvanized support bows and AQUA-Zyme tarp rolling hardware.

One (1) 5″ scraper with a 20′ handle shall be attached to the outside of the dewatering unit for easy access and removal.

One (1) sliding 45″ x 7′ 6″ x 1/4″ aluminum splash guard shall be mounted onto the top of the dewatering unit.

One (1) flat shovel shall be provided for monitoring the flocculation of the liquid material as it is discharged into the dewatering unit.

Dewatering Unit must be capable of accepting 20,000 gallons of liquid material @ 1  1/2 – 2% solids within 2 hours.