SITE INFORMATION AND CORRESPONDENCE

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CHRONOLOGY Chevron Service Station 9-1452 Page 2 09/29/97 The EHD denied site closure because the monitoring wells were located up-gradient of the USTs, and directed a work plan be submitted for additional site assessment. 04/24/01 Date of Site Assessment Work Plan, submitted by SECOR International, Incorporated (SECOR) that proposed the advancement of three Geoprobe borings for soil and groundwater collection. 05/03/01 The EHD approved Site Assessment Work Plan dated April 24, 2001. 10/29/01 Site Assessment Report and Work Plan for Further Assessment was submitted to EHD by SECOR. Analytical results reported 0.19 mg/kg MTBE in one soil sample collected from GP-2 at .32 feet bsg; Groundwater collected at 36 feet bsg from GP-1 contained MTBE and tertiary amyl methylether (TAME) at 79 micrograms per liter (gg/L) and 6.3 µg/L, respectively; groundwater collected at 37 feet bsg from GP-2 contained benzene, xylenes, MTBE, and TAME at concentrations of 0.85 µg/L, 0.51 µg/L, 890 µg/L, and 52 µg/L, respectively; and groundwater collected at 39 feet bsg from GP-3 contained benzene, xylenes, MTBE, and TAME at concentrations of 0.51 µg/L, 0.91 µg/L, 76 µg/L, and 5.3 µg/L, respectively. SECOR proposed installing five additional monitoring wells. 11/07/01 The EHD approved Site Assessment Report and Work Plan for Further Assessment dated. October, 29, 2001, for the installation of two shallow and three deep monitoring wells and the performance of slug tests. 01/07-09/02 Shallow monitoring wells MW-5S and MW-6S, and deeper monitoring wells MW-5D, MW-6D, and MW-7D were installed onsite. 06/11/02 Date of Site Assessment Report and Work Plan for Further Assessment submitted by SECOR that reported results from the slug tests and groundwater results from the newly installed monitoring wells. SECOR proposed advancing two cone penetration test (CPT) borings to assess vertical delineation and installing one monitoring well to facilitate an aquifer pump test. 07/01/02 The EHD approved Site Assessment Report and Work Plan for Further Assessment dated June 11, 2002. 02/04-05/03 CPT-1 and CPT-2 were advanced onsite to assess soil stratigraphy and collect depth-discreet groundwater samples.