SITE INFORMATION AND CORRESPONDENCE FILE 1

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I The MPX Approach The Multiphase Extraction (MPX) or bioslurp concept is a relatively new, innovative approach to site remediation at petroleum release sites that have LNAPL contamination. The MPX system is designed to recover free-phase LNAPL via vacuum-enhanced pumping, while simultaneously removing volatiles and initiating vadose zone remediation via bioventing. MPX has been used with success at Fallon Naval Air Station where more than 8,100 gallons of JP-5 had been removed in 14 months (Kittel et.al.,1994). Currently the Air Force has 34 sites which have or plan to have bioslurping systems in operation (Battelle, 1995). The MPX system utilizes a high vacuum liquid ring pump connected by PVC piping to an extraction tube placed in each well.The extraction tube is inserted into a 50 mm(2") well and by means of adjustment, can extract (1) only vapors, (2) vapors with entrained liquid, or (3) only liquid. The differential enhancement of product thickness can be accomplished by pressure differentiation either through drawdown or upwelling. The MPX overcomes many of the drawbacks of more traditional skimmer and dual pump systems. Some of the significant features of the MPX are that it: • Enhances LNAPL recovery via vacuum-enhanced pumping; • Utilizes existing 50 mm(2")wells; • Requires only one pump to extract from multiple wells, reducing capital and maintenance costs; • Simultaneously treats the vadose zone via bioventing; • Could be optimized to significantly reduce the ratio of groundwater extracted per gallon of fuel recovered, compared to conventional dual-pump recovery systems; • Can be designed to simulate vacuum-enhanced recovery (to achieve an increase.of hydraulic gradient through negative pressure; • Provides suction lift greater than the theoretical maximum due to liquid entrainment-' Can be converted easily to a conventional bioventing or vapor extraction system when free product removal activities are completed. • The system does not have a high cost for equipment because it does not rely on additional pumps and sensors as do the traditional pump and treat systems. Our approach was to initially remove low-weight volatiles as quickly as possible and then convert the system to a bioventing emphasis while simultaneously removing LNAPL from the - aquifer. Hydraulic control by vacuum enhancement was considered a secondary feature of the system, however, hydraulic control could not be established until the plume has been completely defined. 4 M� 382