Environmental Engineering Reference
In-Depth Information
5.5.2 Residual biotreatment (RB) monitoring and assessment
The postflush assessment of the ethanol-enhanced in situ microbial degra-
dation of the chlorinated solvents is ongoing. This assessment of in situ
reductive dechlorination, the residual biotreatment phase of SERB, is based
on site monitoring of geochemistry and contaminant chemistry as well as
laboratory and field evaluations of the impact of ethanol on site microbial
communities.
Groundwater samples from the monitoring wells at the site have been
collected and analyzed quarterly for 2 1 / 2 years along with additional site
characterization activities (Table 5.4). A database has been established that
contains the measured results, including residual ethanol concentrations, its
possible metabolic products, PCE and potential biotransformation interme-
diates, and other geochemical parameters.
The compiled data were graphed by individual wells to show changes
in concentration of the parameters over time. Relatively complete data sets
were obtained for all MW- and C-wells. IWs and RWs were not sampled
consistently throughout the field evaluation; thus, the bar charts of this data
are somewhat limited. IW-1 to IW-3, RW-2, and RW-5 were not sampled after
September 1999.
Contour plots of the data were made to better visualize the changes in
the parameters over time. Surferâ„¢ was used to create these contour plots
Table 5.4 Sampling Dates and Activities at the Sage's Site
Date
Event
July 16, 1998
Preethanol flush groundwater monitoring, site
characterization, partitioning tracer test
August 11, 1998
C-wells sampled (included with preethanol flush)
August 9-15, 1998
Cosolvent flushing test
August 15, 1998
Partitioning tracer test, hydraulic containment
August 25, 1998
End hydraulic containment
September 8, 1998
1-month groundwater monitoring
October 20, 1998
2-month groundwater monitoring
December 3, 1998
3.5-month groundwater monitoring
January 26, 1999
5.5-month groundwater monitoring
May 26, 1999
9.5-month groundwater monitoring
July 14, 1999
11-month groundwater monitoring
Hydrogen gas survey, core sampling
September 23, 1999
13.5-month groundwater monitoring
March 14, 2000
19-month groundwater monitoring
June 14, 2000
22-month groundwater monitoring
July 13, 2000
23-month groundwater sampling (partial)
Core sampling
September 23, 2000
25-month groundwater monitoring
December 29, 2000
28-month groundwater monitoring
March 20, 2000
31-month groundwater monitoring
 
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