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Mr.Ron Rowe <br /> C A M B R I A June 19, 2000 <br /> Groundwater Monitoring: Since installation, these wells have been monitored quarterly for <br /> TPHg, BTEX and MTBE. Reported MTBE concentrations are typically confirmed using EPA <br /> Method 8260. <br /> TPHg and BTEX have not been detected in MW-2 or MW-3. Only low concentrations of MTBE <br /> have been detected in MW-2 and MW-3 by EPA Method 8260. MW-1 contains the highest and <br /> most consistent concentrations of petroleum hydrocarbons and MTBE. Detected TPHg and <br /> benzene concentrations in MW-1 have ranged from 120.to 460 parts per billion (ppb) and 0.50 to <br /> 1.6 ppb, respectively. MTBE detected in MW-1 by EPA Method 8260 has ranged from 120 to <br /> 1,800 ppb. <br /> Groundwater: Depth to groundwater, as measured in the onsite monitoring wells, has ranged <br /> from approximately 15 to 21 fbg. The local groundwater gradient has ranged from south to west- <br /> southwest. <br /> PROPOSED SCOPE OF WORK <br /> Cambria proposes a phased assessment approach to further define the extent of hydrocarbons at <br /> the site. For the first phase of work we propose to advance one Geoprobe boring onsite <br /> upgradient of well MW4 and the former USTs and five Geoprobe borings on private property <br /> west of the site. We intend to use the data gained from the initial phase of assessment to <br /> determine locations for two additional groundwater monitoring wells. The proposed boring <br /> locations are shown on Figure 1. Cambria's Standard Field Procedures for Geoprobe Borings and <br /> Groundwater Monitoring Wells are presented as Attachment A. <br /> Specific tasks to be performed during the assessment include: <br /> Utility.Location: Cambria will notify Underground Service Alert of our drilling activities to <br /> identify utilities in the site vicinity. <br /> Site Health and Safety Plan: We will prepare a comprehensive site safety plan to protect site <br /> workers. The plan will be reviewed and signed by all site workers and kept on site at all times. <br /> Permits and Right-of-Entry Agreements: Cambria will obtain boring/well permits from San <br /> Joaquin County Department of Public Health Services .(SJCPHS) and necessary right-of-entry <br /> agreements or encroachment permits prior to commencement of field activity. <br /> Notification: The SJCPS will be notified at least 48 hours prior to field work. All work may be <br /> witnessed by SJCPHS staff. <br /> 2 <br />