SITE INFORMATION AND CORRESPONDENCE FILE 2

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Message - Page 1 of 2 Mike Infurna [EH] From : Art Deicke [adeicke@advgeoenv.com] Sent: Monday , July 23 , 2007 4 : 55 PM To : Mike Infurna [EH] ; Margaret Lagorio [EH]; Nuel Henderson [EH] Cc: Bob Marty; Bill Little; ngmpics@pacbell .net Subject: Nomellini Construction Company Site San Joaquin County EHD, As requested via a phone call from EHD (Mr. Infurna) to AGE (Mr. Little) on Monday 7-23-2007 afternoon, we present our reasons for disagreeing with EHD determination in correspondence dated 08 June 2007 that seven ground water monitoring wells, including three off-site wells must be destroyed and replaced with wells located within discrete hydrogeologic units. At this time, we do not believe the destruction of EHD-approved and permited wells MW-3 through MW-9 will hasten clean-up at the site. As you are fully aware, all well installation at this site have gone through a rigorous work plan submittal/EHD approval/permitting process . No wells have been ' arbitrarily installed at the site. We do not believe , as EHD states, that wells MW-3 through MW-9 provide a conduit to cross- contaminate separate hydrogeologic units at the site. When wells MW-3 through MW-9 were installed, depth to ground water was approximately 32 feet bsg and the wells were constructed appropriately for the water levels in 1991 to 1994. Wells MW-3, MW-4 and off-site MW-7 have been hydrocarbon-impacted since the first samples were collected in 1991 to 1994 when water levels were at approximately 32 feet bsg and these wells have remained impacted when water levels increased to the present day levels of approximately 15 feet bsg. Additionally, CPT samples collected in 2004 indicated soil was impacted at 70 to 90 feet bsg while wells MW-3 through MW-9 are screened to a maximum depth of 52 feet bsg. Apparently, the impacted ground water is moving downward through the soil, not the wells. No definitive data that shows permeable flow units are continuous and do not terminate into less permeable units at the site. CPT geotechnical boring logs do NOT indicate a continous sandy or more permeable flow zone that connects the four on-site CPT locations. The sandy, more permeable flow zones appear and disappear throughout the sub-surface of the site . Off-site wells MW-5 and MW-9 have remained relatively non-impacted for the past 7 or more years and serve to delineate the southwest and east of the plume. On-site well MW-6 had recent reported impacts only during the past year. Well MW-8 has remained non-impacted the past seven years and serves to delineate the north, although at some distance. Each of the wells EHD states must be destroyed (MW-3 through MW-9) have current and viable assessment function or can provide future remediation functions, i . e. , wells MW-3 . MW-4 and MW-6 could be used for dual-phase extraction. At this time, it appears premature to destroy functioning wells that have current and may have additional (future) purpose. If additional assessment is required, then additional wells can be placed 7/24/2007