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I San .Joaquin County DIRECTOR Donna Henan, REHS Environmental Health Department ASSISTANT DIRECTOR 600 East Main Street auric Coiulla , REHS Stockton , California 95202-3029 PROGRAM COORDINATORS - ' •/ -- - --- - -- Carl 8orgman. REHS \•�o . , . - .« , . 'P% Mike Huggins, RENS, RDI .q �IFORc>i;• Websifer www.sjgov.org/ehd Margaret Lagorlo REHS Phone: (209) 468.3420 Robert MuGellon. REHS Fax: (209) 464-0138 .!off Carruesro. REHS. RDr Kasey Foiey, 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 RO#: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 (Le . 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 , 4, 5 , 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 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 HU-4 in these areas.