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ARTIV ENT ENVIi�ONl� F y ENTALUEALTu EP -� SAN JOAQUIN COUNTY Unit Supervisors a u H Carl Borgman,R.E.H.S. o?a, -:o0 ,.,•:�,� -•.� hird Floor � ins,R.E.H.S.,R.D.I. 2: z Donna R.Heran,R.E.H.S. 304 East Weber AveAvenue, Mike Hang ::4,'= ,•� Douglas W.Wilson,R.1;.H.S. Director g H. Stockton, California 95202-270 i:. Al Olsen,R.E•H.S. Margaret Lagario;R.E.H.S. _ Program Manager Telephone: (209) 468-3420 Robert McClellon,R.E.H.S. A.S. Fax: (209) 464-0138 Mark 13arcellos,R.E.H.S. Laurie A.Cotulla,R.E Program Manager JAY JAHANGARI JUN 2 4 20OZ t PORT OF STOCKTON PO SOX 2089 STOCKTON CA 95201 Re: Pork of Stockton Site Code:12$2124 Site 3, Port Roads 13,14 & G RO#: 000673 Stockton, CA. Your consultant, Geomatrix, has asked San Joaquin County Environmental Health Department (EHD) to comment on their May 17, 2002 "Results of Assessment and Recommendations for Monitoring Well Placement, UST Site No. S' report originally sent to Mr. Michael M. Luksic. EHD has reviewed the document and offers the following comments for your consideration. The report detailed the advancement of six direct push soil borings placed on February 28, 2002 under a boring permit issued by EHD. Soil samples were collected from about 20 and 40 feet below ground surface (' bgs) and analyzed for TPHg, BTEX, and 1,2- DCA by EPA Method 8260B. Groundwater samples from borings "133-8 thru B3-13" were collected from discrete-depths of 20' and 40' bgs and were also analyzed for the same petroleum constituents. The laboratory results indicated that the soil and groundwater samples were non-detect for petroleum hydrocarbons. As a screening tool, the push points were successful in helping to determine some of the lateral and vertical extents of the petroleum impact outside of the area of the former UST pit. Recommendations included in this report specified installing monitoring wells with 15' screened intervals mostly outside the zone (dotted line) your consultant has identified as impacted. One monitoring well was proposed within the zone, but approximately 80' east of the area where the three (3) existing monitoring wells are located. The groundwater samples from these three wells have consistently contained significant levels of petroleum contamination since their installation in 1999. Additionally, your consultant has proposed removing/destroying the three existing monitoring wells, but did not offer a replacement well in this area. EHD has some concerns with the well placements, specifications, and the removal proposal. By removing all of the monitoring wells from an area that has consistently been impacted by petroleum constituents in the groundwater and not proposing to replace them, you may be placing yourself in a position of being unable to fully evaluate the full extent or mass of the residual petroleum impact.