Below Ground Oil Water Separators

Smaller footprint, higher removal efficiency


Contact product manager,
Paul Desmarais
(508) 399-5771

ProductsOil Water Separators

Below Ground Oil Water Separators

Hydro Quip’s Below Ground Oil Water Separators are newly designed.

Since below ground oil water separators first entered the marketplace, there has been little innovation with the design. Most conventional designs are based on a 10:1 ratio requiring long retention times and resulting in larger units. Over the years, SPCC and NPDES have become more stringent in their guidelines, permits, and fines, yet the 10:1 design has not adapted to accommodate these ever-changing regulations.

This new design has a smaller footprint and a higher removal efficiency. It will lower your total cost of ownership by reducing media replacement frequency, disposal fees and maintenance costs.

The HQB-ES model services industries that need to prevent contaminated runoff and spills from getting into public treatment plants and natural waterways. Our design not only exceeds API 421 guidelines and meets local SPCC and NPDES Permits, but it is also capable of achieving a discharge limit of 5ppm or less in accordance with CEN EN 858-1. (See standards and regulations for more information.)

The new design incorporates a grit chamber with every model to handle settleable solids. Our equipment can be easily cleaned through the removable vapor-tight cover(s), so all servicing and maintenance can be performed outside.

Below Ground Oil Water Separators

Our below ground separator stands out from the competition because we base our design on a Reynolds Number of less than 500. A low Reynolds number is required to achieve the rise times of the oil, creating better separation of the oil from the water.

Below Ground Oil Water Separators with Effluent Pump Out Chamber

For pumping water to downstream treatment, a below ground separator design with effluent pump out chamber is available.

Like all our other equipment, these models can be customized to your needs. We can also provide calculations signed by a registered professional engineer. Our calculations take into account potential surge and flow rate, particle characteristics, and temperature. We offer a variety of options for the below ground oil water separator.

Equipment Options

  • Single Wall
  • Double Wall with interstitial space for leak detection
  • Hold down straps
  • Traffic rated covers
  • Concrete deadmen
  • Leak Detection and Level Indicating System
  • Variety of Coating Options (Internal and External)
  • Submersible Pumps
  • Control Panels


  • Diverse wastewaters
  • Events that produce stormwater runoffs
  • Spill containment
  • Vehicle maintenance facilities and washing operations