E
 C
 c-
 0

 0.1
 0)
 0
 0
 LU
 0
 I--






 0 1 2 3 4 5 6

 Ethanol Concentration (%)


Figure 3-1. December 1998 MLS source zone TCE concentration as a function of ethanol
 concentration in the subsurface groundwater.

3.3 Source Zone Transect Concentrations

 The source zone concentrations were monitored for the six-year period after the flushing

pilot test at the MLS wells. Across the source zone transect created by MLS-1, MLS-3, and

MLS-7, the concentration of PCE, TCE, DCE, and VC was determined for each well and depth.

The data for each of the chlorinated species is available in Appendix C. Table 3-2 presents a

summary of the molar sum results, using the method described earlier.

 For the first year after the flood, the mean molar sum in each MLS showed little

variability. The source zone transect MLS detected a slight increase in molar concentrations in

January 1999, 5 months after the flood. By May 2000, the mean concentration molar sum began

to increase significantly. In 2002, the concentrations increased markedly and then began to