vapor liquid separator tank

City Convenience Store Environmental Remediation Site

MAE2 was selected to design and build a remediation system for a convenience store site in mixed use city location.

The consultant conducted a multiple day test at the site. The pilot study indicated a need for a high vacuum system that could treat extracted groundwater at 10-15 GPM and to remove large amounts of free product gasoline. MAE2 used this data to design a system that would extract and treat groundwater and free product from 6 wells located on site. The water needed to be treated to meet the discharge limits for water quality and suspended solids required by the local POTW.

MAE2 used the pilot test data to design and provide written specifications for a Multi Phase Extraction and Groundwater Treatment system. The system needed to remove and treat TPH-Gasoline concentrations as high as 230,000 PPB and MTBE concentrations of 4,600 PPB along with free product gasoline.

The system uses 3 high vacuum rotary claw pumps, providing over 700 ACFM flow at 18” HG vacuum, to extract impacted groundwater and vapors. The client prefers to use multiple pumps operating in parallel rather than a single large pump. This design provides more flexibility to save energy as site needs change over time, along with redundancy to reduce downtime. The system uses a 6 point custom inlet manifold and a marine grade aluminum 120 gallon Air Water Separator.

A progressive cavity transfer pump is used to pump the water to a 20 GPM Oil Water Separator to remove any free product gasoline. Progressive Cavity pumps are selected because they do not create the chemical emulsification of the gasoline and water that other pumps cause. After the Oil Water Separator removes the free product a centrifugal transfer pump sends the water through a bag filter to remove solids and particles from the water before being treated by an oversized Poly Stackable Tray Air Stripper.

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The stripper is oversized to provide additional residence time to treat the MTBE. Finally the water is pumped through another bag filter and then two 250 LB Liquid carbon vessels before being discharged to the POTW.

The custom integrated PLC control panel provides runtime hours, vacuum trends, temperature, carbon vessel pressure and water flow totals. The system uses a cellular data connection allowing full system control and data access through easy to use web browser access. The data allows easy access to system operational status and the data needed for writing reports as required by the regulators.

This Environmental Remediation System uses the following components and subsystems

Vapor Liquid Separator Tanks

Vapor Liquid Separator (VLS) or Knockout Tanks are used to remove liquids from airstreams in Soil Vapor Extraction and Dual Phase Extraction systems.

MAE2’s VLS tanks are custom designed based on air flow requirements and come in a range of sizes. The tanks can be constructed from marine grade aluminum or stainless steel. Each tank is custom built to your specification and can have inlets, site tubes, pump out and drains arranged in any orientation you choose. A full 3 CAD drawing will be provided to you for approval prior to construction.

Typical options include 2” clear site tube assembly, Single Point High level switch or multi point pump out switch, vacuum relief valve, vacuum gauges, sample ports, sturdy steel reinforced clean out plug and drain valves.


  • Skid Mounted, Custom Water Tight Secondary Containment Enclosures
  • Secondary Demister Elements
  • MPT, FMPT and Flanged Inlet/Outlet Fittings
  • Custom Inlet Filters
  • Pump Out Packages