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i WALLAcE•KUHL&ASSOCIATES,AC. APPENDIX FIELD PROCEDURES Monitoring Wells Three monitoring wells will be drilled and sampled using hollow-stem augers. Well construction will utilize four-inch diameter PVC casing with a screened interval extending from a minimum of 10 feet below water to a minimum of five feet above the water level. The slot size of the four-inch casing will be 0.02 inches. Number 3 sand will be used as the filter pack and will extend from the bottom of the screened interval to a minimum of three feet above the top of the screened interval. A minimum two-foot bentonite seal will be placed above the filter pack and a grout seal placed from the bentonite seal to the surface. A locking well cap will be installed along with a traffic-rated Christy box. After installation, the wells will be surveyed to mean sea level for determination of the local hydraulic gradient. Plate 2 shows a construction diagram for a typical monitoring well. Soil_Samp)€_i_ng Soil samples will be collected from the wells using a modified California sampler containing two-inch diameter, six-inch long brass tubes, cleaned with trisodium phosphate. Samples will be screened in the field using an organic vapor analyzer (OVA) at a maximum of five foot intervals from surface to total depth. Additional samples will be collected if the OVA indicates hydrocarbons are present or if lithological boundaries are encountered. Sample tubes will be sealed with aluminum foil, plastic end caps and sealed with tape. All samples will be preserved on ice and selected samples submitted to a California-certified laboratory for analysis. Soil samples will be analyzed according to EPA test methods modified 8015 and 8020 for detection of total petroleum hydrocarbons and BTX&E (benzene, toluene, xylene and ethyl benzene). Ground Water Development. Purging and Sampling Upon well completion,the water levels will be measured using an electrical well sounder, and the well checked for free product using a clear bailer. If no free product is observed, the well will then be developed using a surging block for a minimum of fifteen minutes per well. Three to five borehole volumes of water will then be removed by use of a positive displacement pump or until the parameters of Ph, turbidity, and conductivity have stabilized. After a minimum of 24 hours from the time of development, the water level in the well will be measured again and the water checked for visual signs of free product using a clear bailer. The well will then be purged of an additional three to five borehole volumes using the positive displacement pump. Water samples will then be collected using a new polyethylene disposable bailer. Ground water samples will be obtained from the three wells following development procedures. The water will be analyzed using EPA method 8015 modified and 602 for TPH and aromatic compounds. Pumping equipment will be cleaned prior to use and between each well with a trisodium phosphate cleanser to minimize the potential for cross contamination. All water removed during development and purging operations will be stored on site in sealed 55-gallon drums.