SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Response to SJCEHD's 8-19-08 Letter—Page 4 Joe's Travel Plaza,15600 S. Harlan Road the changes have been slow,they have been steadily decreasing, indicating the diminishing nature of the plume and the effectiveness of natural attenuation in the vicinity of this well and at the site in general. The groundwater plume still covers the entire 3.77 acres north of the site.10 10 See Comment No. 1, above. Although, tests for dual-phase extraction and groundwater extraction were performed in June 2004 and December 2005, active remediation has not been performed to control the migration of the contaminant plume." 11 This statement is accurate in that dual phase extraction (DPE) and groundwater extraction (GV`E) testing were performed in June 2004 and December 2005. However, the second portion of the sentence gives the false impression that the results of these tests, once submitted to EHD, were approved by EHD and that remediation has not moved forward because of reluctance on the part of the responsible party. On the contrary, SJCEHD (EHD) failed to approve either of the two previously submitted IRAPs, both of which proposed the use of groundwater extraction. Below is a summary of the testing performed to date,the results,the proposals submitted to EHD, and EHD's responses: • June 2004 — Stratus conducted DPE pilot testing; extraction at well MW-7. Sustained 7.2 gpm. Influent soil vapor concentrations low. Average concentrations at MW-7 during test were only 93 Mcg/L, Deemed technically viable, not cost-effective. • January 2005 — Stratus work plan; proposed additional assessment and the evaluation of site conditions for possible application of ozone injection (via bench scale study); also concluded air sparge not viable due to 1) thin sands 2) MTBE characteristics, 3) insufficient vadose to recapture injected air via SVE. • February 2005 — Stratus IRAP; proposed groundwater extraction (GWE) from wells MW-2, MW-3, and MWO-I x as interim action and pursuit of a discharge permit. • March 2005 — SJCDEH reviewed IRAP but specifically did not approve it, and requested extended pump tests on the three wells proposed for GWE, instead of estimating extraction rates based on the June 2004 DPE test. • May 2005 — SECOR work plan submitted proposing the SJCDEH-requested pump tests. SJCDEH approves the plan. • December 2005 — SECOR conducts the pump tests. Results: MW-3 -5 gpm, 6hrs; MW-2 -6.3 gpm, 6hrs; MWD-lx -6.0 gpm., 4.4hrs. Average MTBE: MW-3 = 240 [;g/L; MW-2 = 87 �g/L; MWO-lx = 196 µg/L. Mean transmissivity 940 gallons per day; hydraulic conductivity 3.8x10- 3 cm/sec. SECOR's estimated capture was 127 feet downgradient. • June 2006 — SECOR submits report to SJCEHD. Results/Conclusions: 5,422 gallon groundwater extracted during test; mass removal of only 3.4 grams MTBE; extraction volume to mass removal ratio indicates GWE may be ineffective. Evaluation of remedial alternatives included DPE, AS/SVE, GWE&T, and enhanced biodegradation. DPE and GWE&T deemed 4