SITE INFORMATION AND CORRESPONDENCE

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bgs. The 30, 35, 40, and 45 foot soil samples from each of the wells was submitted for quantitative analysis of TPHg and benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Methods 8015M and 8020 respectively. Each of the samples contained the requested analytes. The 40 foot bgs soil sample from MW-2 was the most impacted with laboratory reported concentrations of TPHg (880 mg/kg), and BTEX: 9.2, 45, 14, and 77 mg/kg respectively). In June 1991, GAS surveyed the wells relative to a temporary benchmark and measured the depth to groundwater. GAS measured product layers of 6.125 and 7.25 inches in MW-1 and MW-2 respectively. GAS did not report observing an immiscible layer on MW-3; but states that, "water samples were not collected for analysis. GAS reported that groundwater had dropped approximately five feet since 1988; and, that the groundwater had a relatively flat gradient with a slight slope to the south. GAS concluded: that offsite migration was a possibility; the lateral extent of contamination was not yet determined; the water bearing unit at 40 feet should allow recovery of the free product and/or dissolved contamination; that a more northerly source may be contributing to the contamination; and, that 3,000 to 4,000 gallons of gasoline are potentially present. Based on this data, San Joaquin County Health Services, Environmental Health Department (SJCEHD) has requested that the wells be sampled. SCOPE OF WORK This section describes the work proposed to fulfill SJCEHD's request and provide meaningful information on which to base the next phase of investigation. Task 1: Resurvey Each of the wells will be surveyed relative to a "permanent" benchmark by a licensed land surveyor. Task 2: Redevelopment Based on the length of time since MW-1 was installed and developed and the potential that MW-2 and MW-3 were not developed, each of the wells will be (re)developed. Prior to development each of the wells will be subjectively checked for an immiscible layer by removing a bailer of water for visual inspection. If a product layer is observed, the on site geologist will attempt to remove the layer by bailing prior to developing the well. Product (if present) will be stored in a 55-gallon drum onsite pending proper disposal by the client. Each well will be developed by surging indigenous water in and out of the well screen. Surging will be performed using either a weighted bailer and/or a surge-block. After surging, a bailer will be used to remove sediment laden water from the monitor well. Surging and purging will continue until each well is relatively free of fines or a maximum of 10 well volumes has been removed. Purge water will be stored in 55-gallon drums and left onsite pending review of disposal options. Any tools which will be used in more than one of