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Mr Harlan Knoll, REHS 3 July 24, 1992 nondetectable concentrations of total lead. Stockpile concentrations of TPH-G ranged from 600 to 19,000 ppm, benzene from ND to 37 ppm, toluene from 3 to 490 ppm, ethylbenzene from 1 to 150 ppm, xylenes from 44 to 1400 ppm. S-ile Assessment Work Plan The Site Assessment field program will be performed in two separate field investiga- tion phases. The health and safety plan for this field program can be found in Appendix A. The first phase will consist of a soil-vapor survey Soil-vapor survey sample locations and the rationale for placement locations are discussed further herein. Upon completion, the results of the soil-vapor survey will be summarized in a Soil Vapor Survey Report which will also recommend any resultant modifications to the scope of work for the second phase of the field investigation The second phase of field investigation will consist of the drilling program The drilling program will include soil boring and soil sampling and the installation of ground water monitor- ing/vapor extraction wells. The results of both field investigations will be summarized in a Site Assessment Report The following sections outline the methods proposed for the soil-vapor survey, drilling and soil sampling, well installation, and vapor extraction testing or well development and ground water sampling, as appropriate. Phase I - Soil Vapor Survev The proposed sample locations for the soil-vapor survey are shown on Figure 2. The sample locations were selected primarily to monitor the northwest area of the site in the vicinity of the north pump island where highest concentrations were detected. Prior to commencing the soil-vapor survey, a utility locator will be subcontracted to mark all utility locations on site, as necessary A hydraulic ram will be used to advance soil-vapor probes at the 8 sampling locations at depths of approximately 9 and 15 feet. A clean probe will be used at each sample location Once the soil-vapor probe is set at the selected depth, an adaptor will be attached to the top of the probe to enable hookup of a vacuum pump The soil-vapor will be purged of three probe volumes using a constant flow sampling pump to control ' volume. A soil-gas sample will be collected in a molecular sieve polymer and charcoal tubes, as appropriate The tubes will be labeled with the site name, sample identification, depth, time , and any field observations This information will also be recorded onto a sampling log The sample tubes will be prepared for analyses using thermal desorption and methanol extraction. Samples will be analyzed on-site using a mobile laboratory equipped with a GC/FID for equivalent) The vapor samples collected will be analyzed for TPH-G and BTEX by the Environmental Protection Agency (EPA) Methods 8020 and 8015, respectively Reporting limits will be 10 ppb for TPH-G and 0 1 ppb for BTEX. 1CsnonleEnvlronmental PL191_6341REPORTSIKNOLL RPT[July 22, 19921