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Phase 11 Environmental Site Assessment Mountain House Neighborhood G July 9,2002 Page 3 4.1 SAMPLING PLAN Ten locations (I through 10)dispersed across the approximately 240-acre site were selected for soil sample collection. Two additional soil sample locations (11 and 12) were selected in the southwestern corn producing portion of the site. One discrete surface sample was collected at each location from a depth of approximately zero to six inches below grade. Surface soil samples collected from locations 1 through 10 were composited in a two-to-one ratio by the laboratory, resulting in a set of five two-to-one composite surface samples (sample numbers 1-2, 311, 5-6, 7-8, and 9-10). These composite surface samples were analyzed for organochlorine pesticides and chlorinated herbicides. The two discrete samples (sample numbers I1 and 12) from the southwestern cornfield portion of the site were analyzed for organophosphorus pesticides. The soil sample locations are shown in Figure 3. 4.2 SAMPLING METHODS The surface samples were collected at the surface (zero to six inches) by loosening the soil with a stainless steel shovel. A stainless steel spoon was used to place the loose surficial soil into laboratorysupplied glass jars. Each sample container was labeled for sample identification and placed in a cooler chilled with ice. The stainless steel shovel and stainless steel spoons were decontaminated in the field with a solution of laboratory-grade, non-phosphate detergent and deionized water and rinsed with deionized water prior to use at each surface and deep sample location. The twelve discrete surface samples were shipped in coolers chilled with ice under chain-of-custody procedures via overnight carrier to Severn Trent Laboratories, Inc. in Arvada, Colorado, for analyses. 5.0 LABORATORY ANALYSES The set of five composite surface soil samples (1-2, 3-4, 5-6, 7-8, and 9-10) collected at the site were analyzed for organochlorine and chlorinated herbicides. The two discrete surface soil samples (11 and 12) collected at the site were analyzed for organophosphorus pesticides. Severn Trent Laboratories, Inc., a California certified laboratory, performed the surface soil sample compositing and conducted all analyses according to standard Environmental Protection Agency(EPA)Methods. These methods are as follows: • EPA Method 8081 - a gas chromatographic method for determination of organochlorine pesticides in soil.(formerly EPA Method 8080) • EPA Method 8141A - a gas chromatographic method for determination of organophosphorus pesticides in water and soil. (formerly EPA Method 8140) • EPA Method 8151 A-a gas chromatographic method for determination of chlorinated phenoxy acid herbicides in water and soil. (formerly EPA Method 8150) Organophosphorus pesticides detected by EPA Method 8141A Typically adhere to the very uppermost soil profile and then degrade very rapidly. The area most likely to have received organophosphorus pesticide application is the area where corn was cultivated. Therefore, only the two samples taken from that portion of the site were analyzed by EPA Method 8141A. 6.0 LABORATORY ANALYTICAL RESULTS 6.1 COMPOSITE SAMPLES The laboratory analytical results indicate that the organochlorine pesticides gamma-BHC (lindane), DDD, DDE, DDT, endosulfan I, endosulfan II, endrin, endrin aldehyde, heptachlor, and kepone, and the chlorinated herbicide MCPP were detected in at least one of the two-to-one composite soil samples. The concentrations of these constituents detected in the samples are below the laboratory reporting limits and are estimated concentrations. A summary of detected constituents in the composite samples is presented in N94l w i, CONDOR