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I e THOMAS M. GAU -' DIRECTOR FRITZ BUCHMAN DEPUTY DIRECTOR W for YOU MICHAEL SELLING DEPUTY DIRECTOR STEVEN WINKLER DEPUTY DIRECTOR ROGERJANES BUSINESS ADMINISTRATOR December 14, 2011 Mr. Todd Del Frate, PG California Regional Water Quality Control Board 11020 Sun Center Drive, #200 Rancho Cordova, California 95670 P. O. BOX 1810 -1810 E. HAZELTON AVENUE STOCKTON, CALIFORNIA 96201 (209) 468-3000 FAX (209) 468-2999 www.sjgov.org/pubworks SUBJECT: WE L COMPLETION REPORT, CORRAL HOLLOW SANITARY LANDFILL Mr. Del Frate-�0! Enclosed, please find the Well Completion Report prepared by Geo -Logic Associates describing installation of temporary groundwater monitoring wells in Caltrans right-of-way outside the Corral Hollow Sanitary Landfill property boundary. This report is submitted in fulfillment of the reporting requirement of Item 2 on Page 4 of the Section 13267 Order for Technical Reports issued by the California Regional Water Quality Control Board — Central Valley Region (RWQCB) dated July 7, 2011. These wells were installed in accordance with the Evaluation Monitoring Program (EMP) Plan as approved by RWQCB staff on August 25, 2011. The purpose of the EMP Plan was to assess the extent of groundwater impact by volatile organic compounds (VOCs) related to landfill gas from the Corral Hollow Landfill. This Plan also described contingencies if data from these wells did not allow that assessment. These wells were installed between October 11 and 13, 2011, and were sampled on October 13 and again on November 3, 2011. We requested expedited analyses of both sets of samples to allow quick evaluation. We believe we are ahead of the schedule; we were able to preliminarily evaluate the situation one month before the December deadline to submit this Well Completion Report. You and I discussed on November 21 that samples from the temporary wells show decreasing concentrations of VOCs in a pattern consistent with previous conclusions that VOCs emanate at the northern area of the landfill. And although these data do not allow us to assess the extent of groundwater impact with certainty, they do allow us to identify locations for a second set of wells which we believe will allow that assessment. The second set will be installed with your approval, also on Caltrans property with Caltrans' permission (Figure 1). Because the rainy season is upon us, we expect that surface conditions will allow the installation of the second set of wells in the spring. We are proceeding with application for encroachment onto Caltrans property and well drilling permits based on my understanding that these locations are acceptable to RWQCB staff. Please confirm that this understanding is correct.