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Y .WOO 2.4 Pumping Hist_yr Monitoring wells MW-2 and MW-4A were converted to groundwater extraction as part of in situ bioremediation activities (see below). initial pumping rate Of 15 gpm was not sustained. It is presumed that the sand pack or well screens have been clogged with silt, or organic matter from microbial growth. Current attainable pumping is on the order of 5 gpm or less. Pumping from MW-6 has not been attempted at this time. 2.5 Bioremediation Activities A program was initiated and operated by Chemical Specialties International (CSI) to retnediate the aquifer in-place using inoculations of microorganisms introduced into wells MW-2, MW-4A, MW-6, MW-7 and the former rinse water pond. The first inoculation was on May 14, 1993, although the program did not ofrcially commence until September of 1993. The dates and locations of inoculations performed so far are listed in Table 2. In addition, pumping from MW- 2 and MW-4A was initiated in July of 1993. Pumped water was aerated and allowed to infiltrate back into the aquifer through the former rinse water disposal pond. Samples of groundwater from monitoring wells were collected throughout the bioremediation activities. Charts of the chloroform concentration with time in each of the wells in the bioremediation program are provided in Appendix B. A comparison of mean chloroform concentrations in each well before and ager bioremediation sampling began (September 1993) is shown in Table 3. Since the beginning of bioremediation activities, the chlorofonn concentration in MW-4A has decreased from a mean of 1071 with a standard deviation of 624 to a mean of 599 with a standard deviation of 356. Chloroform concentrations greater than two standard deviations above the post-bioremediation-program mean have not occurred in this well for a frill year, whereas before the bioremediation program began half of all samples were above that level. Notwithstanding relatively smaller increases in chloroform (8 to 90 ug/1) which have occurred in MW-2, MW-6, and MW-7, Triple C management is sufficiently encouraged by the reduction in chloroform concentration in samples from MW-4A to elect to continue the bioremediation program. Table 2. CSI 11ioremediation inoculation Dates Date MW-2 MW-4A MW-6 MW-7 Pond May 14, 1993 x x x May 17, 1993 x x x Aug 27,1993 x x Sep 10, 1993 x x x x Oct 16, 1993 x Dec 1, 1993 x x x x x Mar 22, 1994 x x May 17, 1994 x x May 23, 1994 x x x Jul 22, 1994 x x x x x Aug 5, 1994 x x x x x Sep 6, 1994 x x x x x 01% llk�" L, 6 CONDOR