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7 <br /> 110 Sonora, Stockton, chronology <br /> ' Page 2 <br /> had PID readings from 10 to 40 feet. PID readings on the other <br /> borings were zero until 20 to 25 feet. <br /> 09/28/92 A vapor extraction test was performed at the site on this date. <br /> J,, 10120-22192 Pulse and,pumping tests were performed at the site on these dates. <br /> 1218192 Date. of report on August/September 1992 work. <br /> 9123-29193 Installation of MW5 (screened 37.5 — 57.5 feet), B15 (48 feet deep), <br /> VW4 (screened 33 —40 feet) and.VW5 (dual screened 10 — 30 feet <br /> and 33 — 40 feet) occurred during this time.. <br /> i <br /> 10/28/93 A 500 gallon diesel UST (Tank 2) and a 1000 gallon gasoline UST <br /> (Tank 3) that were next to Tank 1 were removed this date. In <br /> addition a.500.'gallon.diesel. UST (Tank 5) located north of the fire <br /> station building was removed this date. The soil sample beneath <br /> Tank 5 was non detect for contaminants.. <br /> 12/16/93 Date of report on September 1993 work. <br /> { <br /> 01/18/94 A second vapor extraction test was conducted this date. <br /> 06/10/94 Date of EHD closure letter for USTs 4; 5 and 6. <br /> { 10/10/94 A third vapor.extraction test was conducted this date. <br /> 3 <br /> 11/17/94 Date of Final Remediation Plan (FRP) for Soil and Groundwater <br /> Extraction recommends soil.vapor and groundwater extraction. <br /> ' 01/30/95 Date of EHD letter requesting an addendum to the FRP. <br /> 03/31/95 Date of Addendum to FRP. <br /> 07/24/95 Date of EHD letter agreeing that vapor extraction should be <br /> performed but.that-groundwater extraction should not be <br /> �r implemented. <br /> 05/05/98 Date of EHD letter recommending another vapor extraction test <br /> (vapor extraction had not been implemented at the site to date) <br /> since groundwater depth had risen from 41 feet to 27 feet below <br /> surface grade and evaluating using air sparging ,in conjunction with <br /> vapor extraction. <br />