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File No. 8013-01 May 30, 1999 Page 2 The field work for the ORCO placement and monitoring has been conducted by Del-Tech Geotechnical Support Services (Del-Tech). A copy of the Del-Tech 1999 Groundwater Field Monitoring Summary Report is included as Appendix A. 3.1 Baseline Measurements The four groundwater monitoring wells were sampled on March 25, 1999. Prior to sampling, the static groundwater elevations in the wells were measured and recorded. Groundwater elevation �.. measurements are presented in Table I. Specific site conditions and sampling parameters can be found in the Del-Tech Report. Following measurement, the groundwater wells were purged until temperature, pH, conductivity, and oxidation-reduction potential readings stabilized. Down-hole dissolved oxygen (DO) readings were also recorded. ` The wells were allowed to recharge and groundwater samples were collected. The samples were collected using a stainless steel bailer, and placed in pre-cleaned containers. The samples were immediately placed on ice and transported to a State of California certified analytical laboratory for analysis. All equipment was decontaminated prior to reuse. The four groundwater samples were analyzed by BSK Analytical Laboratories (Certification No. 1180). The samples were analyzed for the following parameters: - Total petroleum hydrocarbons as gasoline, TPHg (EPA method 8015 modified/8020); The volatile fuel components "BTEX" (EPA method 8020); Methyl tertiary butyl ether, MTBE (EPA method 8020); Petroleum oxygenates (EPA method 8260 modified). L Additionally, groundwater sample MW-2 was also analyzed for the following biodegradation parameters: Lo - Biochemical oxygen demand, BOD (method SM 5210); • Chemical oxygen demand, COD (method SM 5220); • Nitrate (EPA method 300); �- Phosphate (EPA method 300); Heterotrophic Plate County (method SM 9215). Results of the groundwater analyses are summarized in Table 11. The analytical laboratory data sheets can be found in the Del-Tech Report in Appendix A. 3.2 ORCO Placement Following collection of the groundwater samples, an Oxygen Release Compound (ORCO) sock approximately 3'/z inches in diameter by 10 feet in length was inserted into monitoring well MW-2. The ORCO sock will release oxygen into the subsurface as a means of enhancing biodegradation. Following depletion of the ORCO sock, a determination of its effectiveness will be presented in the subsequent report. L. JJW GEOSCIENCES Inc. V