Rain Water Harvesting

Oil Separator Installation

Please note installation of any Alltrap Engineering products must be done by a qualified plumber failure to do so will deem the product warranty null and void.

Please insure that this document is up to date and presented to manufacturer when making any warranty claims failure to do so will deem the product warranty null and void.

Installation Check List


  1. Excavation for the installation of our separator setup must conform local excavation codes and standards.
  2. Topsoil removed during excavation should NOT be used as approved backfill material. The excavation must be free from any hard or sharp material that may cause damage to the OilSep and Grit tank unit. (Care shall be taken during installation that foreign matter is not introduced into the excavation or backfill)
  3. Excavation should extend at least 300mm around the perimeter of the tanks providing sufficient clearance for installation where required. If the bottom of the excavation provides an unsuitable foundation, additional excavation may be required. In areas with a high water table, continuous dewatering must be provided to ensure that the excavation is stable and free of water.

Install and Level Granular Base

1. A +/- 150mm layer of pea / fine gravel (or approved equivalent backfill compacted) must be installed, leveled, and compacted at the bottom of the excavation to the proper elevation for the installation of the separator base.
2. Install and level the tank.

IMPORTANT: Equipment to lift the units must be of adequate size to lift and lower the tanks without dragging and dropping to ensure no damage. Make use of adequate lifting straps.

3. Fill the Separator with Water up to the Outlet Pipe

IMPORTANT: Any material left behind from installation (e.g. mortar, soil,...) must be removed prior to filling the tanks with fresh water. Fill the separator via the Grit Tank until the OilSep unit is full, and water leaves the separator through the outlet structure. Make sure that the spill control valve is secured in an open position

4. Granular Backfill to the Inlet and Outlet Pipes

Compacted Pea Gravel (or an approved equivalent backfill compacted to 98% of Standard Proctor Density in each layer) must be placed in uniform layers of 150mm (6") to not more than 200 mm (8") in depth up to the bedding for the inlet and outlet pipes.
Note: Backfill is not to contain topsoil

5. Inlet, Outlet and Vent Pipes

Install standard pipe bedding for the inlet and outlet pipes per the sewer design. Attach inlet and outlet pipes to the OilSep and GritTank unit

6. Frame and Cover

Place the frame above the opening to match the top of grade elevation. Make sure the frame is not in direct contact with the top of the OilSep or Grit Tank. A gap of 1” to 2” is required to prevent the vertical load transfer from the frame to the tank. Pour concrete around the frame to secure it in place, size to be determined by Engineer or local code based on site use.