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2. UVB SYSTEM COMPONENTS 2.1 TREATMENT SYSTEM The UVB treatment system consists of an in situ, 400-millimeter diameter reduced pressure, air stripper/aerator and a 5 horsepower blower and includes a weatherproof cover and moisture knockout The moisture knockout has a built-in stripping unit to treat any accumulated water prior to removal Vapors stripped from groundwater are extracted by the vacuum blower, which is connected to an oxidizer The thermaUcatalytic oxidizer, a Thermtech VAC 25, is designed to destroy vapors in a heated chamber prior to release into the ambient air The Thermtech VAC 25 is permitted, installed, and operating at the site It is equipped to handle volatiles stripped from groundwater by the UVB system A process and instrumentation diagram is included as Figure 2 The UVB system consists of one standard flow circulation well The upper and lower well screens and well casing are 16-inch nominal diameter The well casing is made of mild galvanized steel with a 0 25-inch thickness The lower (Irrigator®) well screen has 4 feet of 0 040-inch slots and a 2-foot-long tight-wind sump with plate bottom The upper well screen is double-cased and has approximately 6 feet of 0 040-inch slots A UVB well diagram is provided as Figure 3 The wellhead is sealed with a steel flange and HDPE cover The internal circulation well components are a fixed packer, a single-speed support pump, and an air stripper The support pump permits a controlled rate of water circulation within the cell that is independent of the airlift pump effect created by the stripping reactor Essentially, the support sump allows a regulated amount of water to enter the air stripping reactor, regardless of the stripping time within the reactor UVB well components are depicted in Figure 4 2.2 UVB SYSTEM GENERAL DESCRIPTION ' The UVB well is an in situ groundwater remediation system which removes petroleum hydrocarbons using a combination of physical and biological processes The UVB system creates a circulation cell that transports the mobile, dissolved phase and residual phase hydrocarbons to a central well casing for treatment The treatment methodology is primarily air stripping, and secondarily bioremediation for the light and middle range hydrocarbon fractions During operation, the water level rises inside the air-tight UVB well due to the reduced pressure generated by the blower Atmospheric air enters the well, also due to the pressure differential, through a fresh air pipe connected to the stripping reactor, which floats in the raised groundwater in the casing The incoming fresh air forms bubbles as it is jetted through the pinhole plate of the stripping reactor into the groundwater in the well casing, creating an airlift effect as the bubbles rise to the surface The support pump controls the flow direction and allows a predetermined amount of water to pass through the well and into the stripping reactor ' WP61 73942 WP M6 TX 5 2