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t City of Stockton A68104.02B August 28, 1996 Page 6 ' Table 4 Peuoleum Product conaitu'uts ftemaiu104 in X011 Miss and.VoUd6lE tiro tip ' Petroleum Product Constituent { Estimated Benzene Toluene Ethylbenzene Xylenes TPH-G Mass in Pounds 00053 0 014 0 011 0 092 42 ' Volume in <0001 <0001 <0001 <0001 07 Gallons < = less than TPH-G = total petroleum hydrocarbons-gasoline range constituents Note The volume of benzene, toluene,ethylbenzene,and xylenes indicated were based on the assumption these constituents comprise, in sum,less than 10%of the mass of a given volume of gasoline The following sections provide an outline of the well destruction procedures 1 3.0 PURPOSE AND SCOPE The purpose of this work was to properly destroy monitoring well MW-1. 4.0 GROUNDWATER MONITORING WELL DESTRUCTION Monitoring well MWA was destroyed consistent with California Well Standards (California Department of Water Resources, 1991) The material which was installed in the original borehole (i e , well casing, filter pack, and annular seal) was removed by "overdrilling" to ' depth of approximately 40 feet BSG The drilling was performed with a Central Mine Equipment CME-75, mobile drill rig equipped with an 8 and 5/8-inch, hollow-stem auger. Drilling operations were performed consistent with Twimng's standard operating procedures ' as outlined in Appendix A A copy of the State of California, Well Completion Report for this destruction action is attached in Appendix B After completing the drilling, the well casing and screen was removed from the borehole. The borehole was then be backfilled with a Portland cement slurry (1 e , neat cement) The slurry was gravity placed through the annulus in the hollow-stem augers in one continuous operation from the bottom to the top of the borehole When the annulus was filled with the slurry, auger flights were be removed (no more than 10 feet at a time) from the 16 borehole, allowing the slurry to uniformly fill the borehole to the surface The upper 18 inches of the borehole was capped with a redi-mix concrete to match the existing portland cement concrete slab at the site.