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S ECOR <br /> Mr. Jeffrey Wong <br /> February 8, 2005 <br /> Page 2 <br /> and fuel oxygenates including methyl tertiary butyl ether (MtBE), di-isopropyl ether (DIPS), <br /> ethyl tertiary butyl ether (EtBE), tertiary amyl methyl ether (TAME), and tertiary butyl alcohol <br /> (TBA) were analyzed by EPA Method 82606. Ethanol and methanol were analyzed in <br /> select samples by EPA Method 80156. Analytes have not been detected above laboratory <br /> reporting limits in MW-1, MW-2, and MW-3 since January 2, 2001, October 18, 2002, and <br /> August 30, 1999, respectively. Since installation of MW-4, analytes have not been detected <br /> above laboratory reporting limits in this well. <br /> WELL DESTRUCTION ACTIVITES <br /> Between December 27 and 29, 2004, SECOR supervised Cascade as they destroyed <br /> groundwater monitoring wells MW-1, MW-2, MW-3, and MW-4 (Figure 1). The wells were <br /> properly destroyed under the supervision of Mr. Jeffery Wong of the County and in <br /> accordance with San Joaquin County Well Standards section 13.17. <br /> MW-4 was cleared to eight feet bgs using a Vac truck. After being cleared, the well was <br /> drilled-out using a limited access rig (LAR) to 65 feet bgs. All of the materials within the <br /> borehole, including the well casing, screen, filter pack, and annular seal, were removed. <br /> Upon discussion with Mr. Wong, it was approved to clear the remaining boreholes to a <br /> depth of three feet bgs. The well casing for each well was cut off six inches above the <br /> bottom of the excavation and removed. The three wells were then pressure grouted, with <br /> the grout extending out of the casing. The grout was allowed to spill over into the <br /> excavation, forming a one foot "cap" or "mushroom". After the grout had set, each borehole <br /> was finished to grade with black dyed cement. <br /> If you have any questions or comments regarding these activities, please feel free to <br /> contact either David Evans of SECOR at (916) 861-0400 extension 234 or Darin Rouse of <br /> Chevron at (925) 842-1572. <br /> Sincerely, <br /> SECOR International Incorporated <br /> QED G E0C ' <br /> � D <br /> Tanya MyersDA&tNI `�• Daniel J. Da s, R.G. <br /> Staff Scientist O�`V1S �` Senior Geologist <br /> Enclosures: No•g435Q- <br /> Q� <br /> Figure 1 Site Plan sT'gT�c OF CP,'`�O <br /> Attachment 1 Regulatory dorrespondence <br /> 1:1Chevron1962581REPORTS1200412004 Well Destruction Report 1.doc <br />