SITE INFORMATION AND CORRESPONDENCE

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OCT 24 '91 09:27 SR I K RF—OND `} P.2!2 w �I STEFFEN ROBERTSON AND KIRSTEN October 24, 1941 Ms. LA. C4t1111a, RENS Program Manager Public Health Services, San Joaquin County 1601 E Hazelton Avenue r Stockton, California 952012009 Res Diamond Dumber,224 North Main, Lodi, San Joaquin County Site Code 2292 Dear Ms. Cotulla: In resP00,se to your letter addressed to Ms. Ann Cerney (Arney) of Diamond Lumber, we propose to complete three borings at the above referenced facility in accordance with your requireinCnts (page 2, para 3). These boreholes will be located so as to allow determination of the groundwater giadient beneath the property, with one of the boreholes being completed within:10 feet of the location of the underground storage tanks (USTs) reproved in 1985. Since the M aelumne River flows SW-NW apprm6ma.tely one quarter of a axile north of the subject property and the general topographic gradient is to the west, then it is likely that the groundwater gradient is to the north or northuvost. This will be determined by installation of piezometers which will allow groundwater level nmonitoring, and accordingly the first boreholes will be placed to the north and south of the LIST "grave" at the property perimeter (sec Figure 1.), with the third borehole being placed at the dovmgradient side of the "grave" and developed as a 2-inch monitor poitt, During drilling,undisturbed drive samples will be collected at 3-foot intervals and at any change in lichology below 15 feet to intersection with groundwater. No samples will be collected above 13 feet since this was the depth of the UST excavation, Samples will be field evaluated utilL-Ing an Organic Vapor Meter, and will be preserved following correct EPA. and LUFT ;Manual chain-of-custody procedures for sample preservation and shipment to a California certified laboratory (Sequoia 'Labs, Redwood City). We propose to use Turner Explorations,License C-57-602720,of Rancho Cordova as our driller,and all field work will be completed under the direct supervision of a California certified geologist. Sample test methods will be as follows; Soils: Total Petroleum Hydrocarbons as gas (modified EPA Mrthod 8015); benzene, toluene, >,ylanc, cthylbenzene (ETEX), EPA Method 8020; and total lead (EPA Method 7421). Nater, Total Petroleum Hydrocarbons as gas and beri=ne,toluene,xylene,ethylberr=nc(BTEX), (EPA Method 5030 and modified 801.5-80M); and total lead (by AA, 239-2) Eaaraction methods will be by EPA Method 5030 for TPH and BTEC sails and waters. Please contact me with any questions, comments, or specific r`,equiremcrrts you may have in order that we might schedule the necessary testing program as soon as possible. With regards, STEFTEN ROBERTSON AND KIRSTEN (U.S.) INC. Rob Gwilym, C.P.G. Principal, Senior Environmental Geostientist s cc. Ann Arucy, Diamond Ir AG/ssl ;Steffen Robertson and Kirsten (U.S.) Inc. 15311 N E q0th Strut. Redmond, Washington, 98052, U.S.A. Tel. (206)1881-22333 Facsimile (206) 881-1581,. C.her offices in- U.S.A , Canada. United Kingdom and Africa yi li ..