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• QUARTERLY GROUNDWATER MONITORING REPORT SECURITY PACIFIC PROPERTY 300 S. State Street Ukiah, California INTRODUCTION In accordance with a request from Bank of America, personnel from j Geological Audit Services, Inc. (GeoAudit) have performed quarterly groundwater monitoring procedures at 300 South State Street in Ukiah, California (the site) . The project background, procedures, findings and conclusions are presented in the following sections. The site location is presented in Figure 1. A plan of the site is presented in Figure 2 . BACKGROUND The site is located in a relatively flat commercial area of Ukiah (Figure 1 - Location Map, 7 . 5 Minute Ukiah Quadrangle, USGS Topographic Series, 1975) . Three 10, 000 gallon underground gasoline tanks were removed from the subject site in 1986. Hydrocarbon contamination in the soil and groundwater was discovered following . the tank removal. Subsequent assessment activities included the installation of five on-site and four off-site groundwater monitoring wells (Figure 2) . A passive monitoring program was performed between the second quarter of 1990 and the first quarter of 1991. During the monitoring program, contamination levels showed considerable fluctuation. Between August 1991 and August 1992 , active mitigation of soil contamination was performed by removing soil in the vadose zone and capillary fringe and bioremediating the excavated soil. A work plan and a work plan addendum for these activities were submitted to the Regional Water Quality Control Board - North Coast Region (RWQCB) on 31 May and 16 July 1991, respectively, and found adequate. To comply with current air quality regulations, a permit to bioremediate the contaminated soil was also secured from the Mendocino County - Air Pollution Control District (Permit No. A/C91-20) . Following completion of the bioremediation project, a report was submitted on 21 July 1992 to the Regional Water Quality Control Board - North Coast Region (RWQCB-NCR) . During excavation and treatment, three on-site monitoring wells • were destroyed (MW-1, MW-3 and MW-5) . On 3 September 1992 three new wells were drilled in the same locations. Two additional off-site monitoring wells were installed on 4 September 1992 . The wells-were initially sampled on 11 September 1992 and results presented in the Monitoring Well Installation and Sampling report dated 9 October 1992 .