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U <br /> CHRONOLOGY <br /> GRANITE CONSTRUCTION CO. <br /> 10500 S HARLAN RD(APN: 193-270-03) <br /> 04/22/92 The date five underground storage tanks(USTs)were removed under Environmental <br /> Health Department(EHD)permit and inspection:two Gasoline,two Diesel,and one <br /> Waste Oil. <br /> 06/17/92 On this date soil analytical results were reviewed by EHD. Wallace Kuhl report dated <br /> May 12, 1992,had soil sample results that were positive for Gasoline and Diesel <br /> contamination. The highest gasoline contamination was found under the east end of <br /> Tank-3 and the highest diesel contamination was found under the dispenser island(P4). <br /> 06/18/92 EHD filed an Unauthorized Release Report and a Notification of Hazardous Waste <br /> Discharge Report on this date. <br /> 02/11/93 Date the site was placed in the LOP. <br /> 03/9-15/93 During this period three monitoring wells(MW 1-MW3)were installed and 17 soil <br /> borings(SB 1-SB 17)were drilled. <br /> 04/29/93 Date of report covering March 1993 work. Groundwater contamination was documented. <br /> 09/22-23/93 Three additional monitoring wells(MW4-MW6)were installed northeast of the former <br /> UST location during this period. <br /> 09/28/93 On this date 700 cubic yards of contaminated soil was removed from the former <br /> dispenser area and stockpiled south of the former UST area, 13 confirmation soil samples <br /> were collected from the excavation and all six monitoring wells were sampled. <br /> 12/02/93 Date of the"Report of Findings"for the work performed in September 1993. Soil and <br /> groundwater samples from MW4-MW6 were non detect for contaminants. Soil sample <br /> results from the excavation were positive for Diesel(13 ppm)and Motor Oil(26 ppm). <br /> 01/17/95 To further define the extent of groundwater contamination,MW7&MW8 were installed <br /> southeast and southwest of the former UST location. Boring B18 was drilled southwest <br /> ofBl6&B17. <br /> 01/24/95 MW7&MW and B18 soil and groundwater sample results were below detection limits. <br /> 04/07/95 Date of "Problem Assessment Report"with a well survey that identified only the 2 <br /> domestic wells on site. <br /> 02/16/99 bate of Groundwater Monitoring and Sampling Report. Groundwater samples were <br /> collected from MW 1 —MW4 on 1/9/98 and 12/17/98,analysis for MTBE was included <br /> and it was not detected. <br /> 08/18/99 The date of "Request for Closure Report". A new well survey identified 33 domestic <br /> wells within 2000 feet of the site. <br /> 11/29/01 Date of EHD letter requiring destruction of production well and connection of the facility <br /> to a public water supply. <br /> 9/17/04 Date the on-site dust control/production well was destroyed under EHD permit and <br /> inspection. The Granite facility has connected to the Lathrop Public Water Supply. <br /> 10/17/05 Date of No Further Action Request/Final Closure Report. The diesel and gasoline plume <br /> is defined and stable and the fuel oxygenates and gasoline additives analyzed for were not <br /> detected. All requirements in the EHD letter dated 11/29/01 have been met. <br />