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� r { NwI r..1 Port of Stockton page 2 Site 3, Port Roads 13, 14 & G. Approval of requests for no further action or evaluations of remedial alternatives are based on a complete subsurface picture of the impact and residual mass of petroleum. EHD recommends that if the existing monitoring wells must be removed, additional, multi-leveled monitoring wells be reinstalled in this area. Soil boring "133-5" yielded elevated levels of petroleum in groundwater samples collected from 20' bgs (610,000 ugll TPHg and 19,000 ugll Benzene) and 40'bgs (220 ug/l TPHg and 10 ugll Benzene). The screened interval for the well proposed in this area is from 10' to 25' bgs only. EHD concurs with your consultant's proposal to place a new monitoring well in this area, but questions why no screened interval is proposed for the sands at 34' to 40' bgs where petroleum constituents were also detected. A separate and deeper-screened monitoring well should be placed in this zone to provide repeatable confirmation groundwater sampling from depths where the previous investigation encountered the petroleum constituents. The vertical extent of the petroleum impact is to be defined before remedial alternatives or closure requests can be evaluated by EHD. Analyses for MtBE, lead scavengers, and the other oxygenates were not included in this last phase of investigation. EHD will require analyses for these constituents by EPA Method 82606 and AA 6010. lf, after two consecutive groundwater sampling events indicate that these constituents are not present, EHD will accept and approve a request to discontinue these analyses. Monitoring well installation and destruction permits are issued after your submitted work plan has been approved by EHD. The well permit application forms and associated fees (installations, $891 destructions, $60) may be submitted with the work pian, or you can wait until the work plan is approved. I hope these comments provide you with some guidance with your upcoming investigation phase. You may contact me at minfurna s'cehd.com or by phone at (209) 468-3454 should you have any questions. Donna Heran, REHS, Director Z mental Health Division Michael J. Infurna Jr., Senior REHS Nuel C. Henderson, Jr. R.G. LOP 1 Site Mitigation Unit IV LOP I Site Mitigation Unit IV MI/ c: CVRWQCB— Marty Hartzell, Sacramento. c: Geomatrix— Brad Loewen, 2444 Main St, #215 Fresno, CA. 93721-2734. c: SWRCB-CUF —Mark Owens, Sacramento.