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• Page 2 December 15,2002 Ethylbenzene and xylene (less than 0 015 mg/kg reported in Borehole (BH) No C-3 as well as ethylbenzene and xylene (less than 0 065 mg/kg reported in BH No C-517) and contamination with heavier fractions (purgeable C6-C12) were found in soil between 25 and 40 FT bgs in BH Nos C-2 and C-416, ranging upwards to extractable petroleum hydrocarbons of 15,500 mg/kg at 25 FT bgs in IBH No, C-517 Groundwater was sampled when encountered in the boreholes MW No 1 was sampled on December 20, 2000 and March 30, 2009 A detectable level of BTEX of 0 500 ug/L was found in BH No C-416 Extractable hydrocarbons were identified in groundwater samples from BH Nos C-1 C-2 C-3 C-4 C-5 and MW-No 1 Ground water was sampled from the single monitoring well in December 2000, April 2001, January 2002 and April 2002 Recent Activity Following resumption of monitoring this year, it became apparent that additional characterization of contamination both on and off site would be required The San Joaquin County Public Health Services, Environmental Health Division (EHD) in ' their letter of April 2, 2002, to WOS's Mr Jeff Hopkins, reaffirmed the county's position and directed installation of at least two monitoring wells on site to confirm the on site groundwater contamination and to provide data to calculate groundwater gradient flow direction Additionally, EHD directed that a 2,000 FT well survey be conducted The area is identified on the attached LOCATION MAP ' Permission to access, bore and sample from the adjacent property was acquired by the client (WOS) A work plan was developed for May 8, 2002 submittal along with application for test well drilling on the adjacent down gradient properties Following conditional approval by EHD, six borings of which five were converted to cased monitoring wells were constructed by Woodward Drilling Company during June 6 and 7, 2002 Soil was sampled and classified by Stellar Environmental Solutions, Inc geologist Fred Hayden RG and Dan Barber PE Reference ATTACHMENT 7 "GEOLOGIST INVESTIGATION-FIELDWORK REPORT" Well construction details include 2 IN PVC casing to about 60 FT with the lowest ' 20 FT slotted at 0 20 IN The annular space of the 8 IN flight augured boring was filled with washed #3 quartz filter sand, topped by a Bentonite chip seal and approximately 36 FT of Portland cement grout upwards to near the ground surface Flush well covers with locking caps were installed on the earlier constructed MW No 1 and the new MW Nos 2,3 and 4 MW Nos 5 and 6 were extended above ground level about 2 FT and encased in mortar filled "stove pipe" covers with guard bolsters to protect from future agricultural activity Del-Tech Geotechnical Support Services developed the monitoring wells and continues to collect samples from MW Nos 1-6 for delivery to Sequoia Laboratory for analysis