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' 17 February 2003 • AGE-NC Project No 95-0137 ' Page 2 of 7 2 1 1 Soil Vapor System.Monitoring and Sampling A magnehelic vacuum gauge was used to measure the vacuum potential at the two Inch Influent line ' between the blower and extraction wells, the flow rate of extracted soil-vapor (influent) was measured using an direct measure flow meter The organic vapor concentrations in the extracted soil- vapor stream was measured before entering the blower(Influent stream)and after exiting the carbon units (effluent stream) using an organic vapor meter (OVM) equipped with a photo-Ionization detector PID (Thermo Environmental 580B, 10 OeV, calibrated to isobutylene 100 ppb) Field measurements, recorded at regular Intervals between September and late December 2002, are summanzed in Table 1 Soil-vapor samples were collected to document trends In concentrations of hydrocarbon vapor in the Msoil v apor e xtracted b y t he S VE n etwork and to d etermine t he t reatment s ystem h ydrocarbon destruction rate Soil-vapor samples from the influent and effluent stream and one inlet sample were collected in Tedlar vapor hags on 21 October,21 November and 12 December 2002 using a vacuum pump attached to the influent and effluent stream The samples were labeled,placed in a pre-chilled cooler and transported under chain-of-custody to transported to McCampbell Analytical Inc (MAI) a California Department of Health Services(DHS)-certified laboratory in Pacheco,California, The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015 Modified, and • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary butyl ether (MTBE) in accordance with EPA Method 8020 �- 2 1 2 In-Situ Air Sparging Monitoring and Maintenance The EnvioSparge IAS system was monitored and serviced over the quarter Regular measurements of the dissolved oxygen in the ground water wells since the Initiation of the remediation system have shown a low to moderate dissolved oxygen Increase in ground water wells Consequently the ' sparging flow rate was adjusted to approximately 4 standard cubic feet per minute (scfin) and to a pressure of 5 pounds per square inch(psi) 2 2 WELL CASING ELEVATION SURVEY ' On 22 November 2002, a California state-licensed survey engineer from Baumbach & Piazza Inc surveyed a reference point on the top of each ground water monitoring well casing at the site to the nearest 0 01-foot relative to the San Joaquin County Bench Mark No M-37, at an elevation of Advanced GeoEnvironmental,Inc