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7 On 16 September 1997 a KBH representative visited the site to correct a manufacturing defect in the SVE unit A temperature controller to the oxidation unit was noted to malfunction,falsely Indicating an excessive temperature in the oxidation chamber, and thereby causing the unit to shut down as a precaution against destruction of the oxidation chamber A new temperature controller was added to the SVE unit, by KBH SPARGING/EXTRACTION SYSTEM OPERATION AND MONITORING The IAS/SVE system was monitored daily for the first week of operation and weekly thereafter During each monitoring event, the depth to ground water and per cent dissolved oxygen were measured for each monitoring well General system maintenance and adjustments were performed at this time The sparging flow rate was adjusted to approximately 7 to 10 scfm and to a minimum pressure of 15 psi Elevated concentrations of dissolved oxygen were detected in monitoring wells MW-1,MW-2 and MW-4, as well as observation wells surrounding the ASO-1 well on the site Dissolved oxygen concentrations In the remaining wells, down gradient showed smaller changes The greatest changes in dissolved oxygen was again observed in monitoring wells closer to the sparging well/points The dissolved oxygen data is summarized on Table 3 Sparging rates were measured at approximately 7 to 10 sefin during each monitoring event A pressure of approximately 15 was to maintain for the air sparging flow rate • The SVE unit operated at varying rates during the observation period Extraction flow rates were calculated to range from 150 to 200 scfm Typically operation averaged at 150 scfm during the period Operation of the unit was attempted at 200 scfm, the maximum operational rate of the unit, however the unit was noted to overheat and automatically shut off apparently to prevent the catalyst beds from dete>>orating An induced vacuum(negative pressure)of approximately 25 to 45 inches of water was measured in the piping between the blower and extraction wells The radius of influence at the well-heads was noted to range from 0 35 inches of water at well MW-4 to 38 inches of water at ASO-3 Three sets of extracted soil gas samples were analyzed for TPH-g, BTEX and MTBE TPH-g was detected in the 09 April, 12 May and 18 June 1997 samples collected from influent vapor stream at concentrations of 1,800 micrograms per liter pg/l, 8,900 µg/l and 5,600 gg/l,respectively BTEX compounds were detected at concentrations as high as 52 µg11 Petroleum hydrocarbons were detected at 100 gg/l the sample collected from the effluent stream on 18 June 1997 ANALYTICAL RESULTS OF GROUND WATER SAMPLES - IAS/SVE STARTUP TPH-g was detected in the water samples from wells MW-1, MW-3, MW-4 and MW-5 at concentrations of 99,000 micrograms per liter fig/I, 6,900 µg11, 100,000 µg/1 and 73 µg/l, respectively Benzene was detected in wells MW-1, MW-3 and MW-4 at concentrations of 19,000 Advanced GeoEnvironmental,Inc