Rural GA Convenience Store Remediation Site
MAE2 was selected to design and build a Multi Phase Extraction and Groundwater Treatment remediation system for a convenience store site in rural GA.
The consultant was tasked with removing free product which was part of a long narrow plume between the tanks and the gas pump island.
The consultant and MAE2 chose a high vacuum system that could treat extracted groundwater at 15-20 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 vacuum wells located on site. The water needed to be treated to meet NPDES limits and was discharged into a roadside ditch.
The system uses 2 high vacuum rotary claw pumps, providing over 500 ACFM flow at 25” 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. A 55 gallon drum with a high level alarm is used as a Product Storage Tank. 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 to a Poly Stackable Tray Air Stripper to remove dissolved phase gasoline. The water is pumped through bag filters, with valves allowing them to be used in parallel or series, to remove solids and particles from the water. Finally the water passes through two Steel High Pressure 250 LB Liquid Carbon Vessels before being discharged to a roadside ditch.
The custom integrated PLC control panel provides runtime hours, vacuum trends, temperature, carbon vessel pressure and water flow totals. The controls use two Variable Frequency Drives (VFD) to convert from 240, single phase power to 240, 3 phase power to operate the system motors.
VFD’s allow users to adjust motor speeds and reduce/save energy. 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.