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delayed until "gradient has been established" and requested that a work plan for installation of an acceptable soil remediation option as described in the Technical Evaluation Report(Dames & Moore, 1994b) be submitted by March, 1995 On March 15, 1995, AFPC requested and received an extension for a response to the PHS- EHD letter On April 14, 1995, Dames & Moore, on behalf of AFPC, sent a letter to the PHS-EHD objecting to the premise that a 100-ppm standard was merited at the site The PHS-EHD agreed to allow AFPC to conduct additional site characterization work and geochemical modeling The results of this additional work are presented in this document and are intended to evaluate the mobility of residual hydrocarbons at the Site, and to evaluate groundwater quality and water level after the record precipitation in 1994/1995 i I 3 0 FIELD AND LABORATORY PROCEDURES This section provides a summary of the field and laboratory procedures used during the study conducted by Dames &Moore A detailed description of sampling procedures is provided in Dames & Moore's November, 1994 Work Plan prepared for this project (Appendix A), which was supplemented by an Amended Work Plan (Appendix B), following discussions with PHS,EHD 3 1 SOIL SAMPLING Two soil boring locations were selected with the approval of PHS-EHD in areas of the site with the highest concentration of residual TPH-d in soils, based on prior soil analyses (Dames & Moore, 1992, 1994a) Soil samples were collected from these two borings and from a third boring converted into a monitoring well (DMW-5) The purpose of the soil borings was to obtain samples from the most impacted material remaining in subsurface soils at the site and to conduct detailed hydrocarbon mobility evaluations of the most impacted soils On May 3 and 4, 1995, a total of 12 soil samples were collected from depths ranging from 21 to 56 feet bgs from 3 separate soil boring locations, designated SB-19, SB-20, and DMW-3 The locations of these borings are shown on Figure 2 Soil boring DMW-5 was located within 10 feet of the former waste oil tank, soil boring SB-20 was located approximately 40 feet southwest of the former waste oil tank and soil boring SB-19 was located approximately 20 feet north of the former diesel tank in the area where high TPH residuals were expected During drilling, a continuous log was prepared and is presented in Appendix C Soils were classified according to the Unified Soil Classification System SAC156 14 4 DAMES &.MOORE