SITE INFORMATION AND CORRESPONDENCE FILE 2

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I San Joaquin County DIRECTOR PQM ' " Environmental Health Department Donna Heran, REHS ASSISTANT DIRECTOR 600 East Main Street Laurie Cotulla, REHS Stockton , California 95202-3029 PROGRAM COORDINATORS Carl Bergman, REHS c'q' • .�` P Website: www.S/gov. org1ehd Mike Huggins, REHS, RDI � tFORt� 9 Margaret Lagorio, REHS Phone : (209) 468=3420 Robert McClellon , REHS Fax : (209) 464-0138 Jeff Carruesco, REHS, RDI Kasey Foley, REHS DANTE JOHN NOMELLINI JUN 0 8 2007 NOMELLINI CONSTRUCTION PO BOX 1461 STOCKTON CA 95201 RE : Nomellini Construction Company Site Code : 1779124 1045 W . Charter Way R0#: 382 Stockton , CA. 95206 SWRCB-CUF#: 552 The San Joaquin County Environmental Health Department ( EHD) has recently discussed the above referenced site with your consultant and the following comments are included for your review. Since our last correspondence dated May 1 , 2007 ( remailed to current address on May 8 , 2007), the EHD has determined that some existing monitoring wells onsite are constructed either across multiple water bearing zones or not constructed in a water bearing zone at all . This concern has been discussed with your consultant, and is now being brought to your attention . Your consultant advised that Table 4 was included in the quarterly reports to illustrate the relationship between the construction of the monitoring well screened intervals and the subsurface soil/lithology they are installed in . Although Table 4 shows clearly defined boundaries between permeable units and the less permeable units ( Hydrological Units —HU ), most of the subsurface lithologies do not maintain the uniform and consistent width , interval , or depth below ground surface that Table 4 shows ( i . e . HU-5 and MW- 11 ) . Additionally, the screened interval shown on Table 4 for MW-2 is incorrect. MW-2 was constructed with the screened interval at 32' bgs to 52 ' bgs, and not the 30' bgs to 50' bgs depicted on Table 4 bar graph . Please correct Table 4 prior to including it in future quarterly reports. The EHD is concerned that monitoring wells MW-3 , 47 57 7 , 8 , 9 , and possibly MW- 11 have screened intervals connecting one permeable unit ( HU-2 ) across a less permeable unit, ( HU-3) to a deeper permeable unit ( HU-4). This situation provides a potential vertical conduit for the migration of contamination from one zone to another, an unacceptable condition . These wells cannot be allowed to remain in place and are to be destroyed and replaced with monitoring wells screened across only one permeable unit. Additionally, newly installed MW- 10 and MW-11 contain elevated II levels of dissolved gasoline constituents but are constructed below HU-4 in a low permeability hydrological unit, therefore these wells do not provide a monitoring well screened across HU4 in these areas .