Laserfiche WebLink
building at Former Tank Site 42 within the interval of approximately 5 to <br /> 11 feet bgs The total estimated volume of TPH-impacted soil beneath the <br /> former warehouse footprint is approximately 210 cubic yards <br /> 36 MASS CALCULATIONS FOR SOIL TREATMENT <br /> ' Mass calculations were completed to evaluate the volume of soil treated at <br /> Site #2 by excavation and aeration Appendix C presents the details of the <br /> ' mass calculations In summary, these calculations indicate that the mass <br /> of TPH and BTEX were reduced by 79 percent and 73 percent, <br /> ' respectively <br /> 3.7 GROUND WATER MONITORING AND EXTRACTION EVENTS <br /> The originally selected ground water remedial alternative for Former <br />' Tank Site #2 involved extraction of a fixed volume of hydrocarbon- <br /> containing ground water from existing monitoring wells Ground water <br />' was extracted from monitoring well MW-1A during three events <br /> December 1993/January 1994, May 1994, and September 1994 The <br /> ground water extracted during each event was pumped into Baker tanks <br /> for temporary storage and subsequently transported via vacuum trucks to <br /> the City of Stockton POTW for direct discharge In October 1996, oxygen <br /> regenerating compounds ORC were introduced to the monitoring system <br />' to enhance natural biodegradation processes <br /> Ground water samples were collected routinely from the five wells <br /> installed at Site #2 during the period from April 1991 through July 1999 <br /> Ground water levels measured during these monitoring events are <br />' consistent with an overall south-southwest (away from the Channel) flow <br /> direction The ground water samples were analyzed for purgeable <br /> hydrocarbons and BTEX constituents as well as general water quality <br /> parameters Analyses during the earliest monitoring events also included <br />' organic and total lead and ethylene dibromide Recent sampling events <br /> have also included fuel oxygenates and 1,2-DCA Tables 6 and 7 present a <br /> summary of the quarterly ground water sample results for Site #2 <br /> The highest concentrations of TPH and BTEX detected since the October <br />' 1993 excavation were in ground water samples collected at monitoring <br /> wells MW-IA and MW-2A Over time, the results of quarterly ground <br />' water samples collected from morutoring wells MW-1A and MW-2A have <br /> shown a steady decline in the concentrations of TPH (as gasoline and/or <br /> diesel) and BTEX in ground water During the most recent monitoring <br /> round (July 1999), TPH as gasoline and unknown TPH were detected at <br />' )RM 17 CAT£Ll US/299610-10/13/99 <br />