United States Solid Waste and EPA 510-F-93-020 Environmental Protection Emergency Response October 1993 Agency 5403W Groundwater Remediation For UST Sites Vacuum Enhanced Pump And Treat Vacuum enhanced pump and treat is a technique that uses a surface-mounted vacuum pump to remove contaminated soil vapors and groundwater simultaneously. This method increases the rate of pumping, reducing remediation time. The pumped water and soil vapors can then be treated with a number of techniques. Vacuum enhanced pump and treat is most effective when used in aquifers with medium to low permeability (silts and clays). This method offers pumping rates that are 3 to 10 times greater than conventional pump and treat rates. Increased pumping rates result in decreased remediation time. Petroleum Types And Constituents • Dissolved gasoline and diesel, jet fuel, and kerosene • Dissolved constituents such as benzene, toluene, ethylbenzene, and xylene (BTEX) ------- Vacuum Enhanced Pump And Treat Advantages limitations System Components Wastestream Treatment Parameters to Monitor1 Cleanup Levels and Timing2 Costs5 • Controls contaminant plume migration and reduces plume concentrations • Increases recovery rate of pumping by 3 to 10 times, reducing remediation time • Effective in aquifers with low permeability • Can remove residuals from dewatered aquifer soils • Can require treatment of vapors from vacuum pump • Generates larger volume of water for treatment in a shorter time than conventional pump and treat • Requires control of water table fluctuation to minimize smearing contaminants • High iron content/hardness can affect water treatment • Vertical or horizontal extraction wells • Trenches • Vacuum blower or pump • Water pumps • Aboveground air/water treatment systems • Vapor treatment options: • Vapor phase biofilter • Granulated activated carbon • Internal combustion engine • Catalytic oxidation unit • Thermal incinerator • Water treatment options: • Air stripping • Granulated activated carbon • Bioreactors • Vacuum/pressure monitoring at well head, pump, blower • Airflow rate • Water discharge rate • Water levels • Constituent concentrations in groundwater • Influent and effluent concentrations from water treatment system • Might not achieve maximum contaminant levels (MCLs) • For an ideal site3, 6 months to 1 year • For an average site4, 6 months to 2 years • For an ideal site3, $80,000 to $120,000 • For an average site4, $100,000 to $180,000 • Higher initial costs than some alternatives, but shorter remediation time might lower total cost '"Parameters to monitor" are for performance purposes only; compliance monitoring parameters vary by state. An Ideal site* assumes no delays in corrective action and a relatively homogenous, permeable subsurface. 4An "average site' assumes minimal delays in corrective action and a moderately heterogeneous and permeable subsurface. 5Costs include equipment, and operation and maintenance. ------- |