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1 <br /> STEFFEN ROBERTSON AND KIRSTEN <br /> _ <br /> October 24, 1991 OOT 2 9 1991 <br /> Ms. LA. Cotulla, REHS CNVIRONMENTAL (HEA! TH <br /> Program Manager � i�^v1i i IJP i1 Vlll�e_ <br /> Public Health Services, San Joaquin County <br /> 1601 E Hazelton Avenue <br /> Stockton, California 95201-2009 <br /> Re: Diamond Lumber,224 North Main, Lodi, San Joaquin County Site Code 2292 <br /> Dear Ms. Cotulla: <br /> In response to your letter addressed to Ms. Ann Cerney (Arney) of Diamond Lumber, we propose to <br /> complete three borings at the above referenced facility in accordance with your requirements (page 2,para <br /> 3). These boreholes will be located so as to allow determination of the groundwater gradient beneath the <br /> property, with one of the boreholes being completed within 10 feet of the location of the underground <br /> storage tanks (USTs) removed in 1985. Since the Mokelumne River flows SW-NW approximately one <br /> quarter of a mile north of the subject property and the general topographic gradient is to the west, then it <br /> is likely that the groundwater gradient is to the north or northwest. This will be determined by installation <br /> of piezometers which will allow groundwater level monitoring, and accordingly the first boreholes will be <br /> placed to the north and south of the UST "grave" at the property perimeter (see Figure 1), with the third <br /> borehole being placed at the downgradient side of the "grave" and developed as a 2-inch monitor point. <br /> During drilling,undisturbed drive samples will be collected at 3-foot intervals and at any change in lithology <br /> below 15 feet to intersection with groundwater. No samples will be collected above 13 feet since this was <br /> the depth of the UST excavation. Samples will be field evaluated utilizing an Organic Vapor Meter, and <br /> will be preserved following correct EPA and LUFT Manual chain-of-custody procedures for sample <br /> preservation and shipment to a California certified laboratory (Sequoia Labs, Redwood City). <br /> We propose to use Turner Explorations,License C-57-602720,of Rancho Cordova as our driller,and all field <br /> work will be completed under the direct supervision of a California certified geologist. Sample test methods <br /> will be as follows: <br /> Soils: Total Petroleum Hydrocarbons as gas (modified EPA Method 8015); benzene, toluene, <br /> xylene, ethylbenzene (BTEX), EPA Method 8020; and total lead (EPA Method 7421). <br /> Water: Total Petroleum Hydrocarbons as gas and benzene,toluene,xylene,ethylbenzene(BTEX), <br /> (EPA Method 5030 and modified 8015-8020); and total lead (by AA, 239-2) Extraction <br /> methods will be by EPA Method 5030 for TPH and BTEX soils and waters. <br /> Please contact me with any questions, comments, or specific requirements you may have in order that we <br /> might schedule the necessary testing program as soon as possible. <br /> With regards, <br /> STEEFFFEN ROBERTSON AND KIRSTEN (U.S.) INC. <br /> Rob Gwilym, C.P.G. <br /> Principal, Senior Environmental Geoscientist <br /> cc: Ann Arney, Diamond <br /> RG/sal Steffen Robertson and Kirsten (U.S.) Inc. <br /> 15311 NE 90th Street, Redmond, Washington, 98052, U.S.A. <br /> Tel. (206) 881-2233 Facsimile (206) 881-1581 <br /> 235 4d4,C0t017a.02L Other offices in: U.S.A., Canada, United Kingdom and Africa <br />