Environmental Engineering Reference
In-Depth Information
Pasquotank River
MW46
MW35D
N
ML35
ML15
MW49
ML14
ML13
ML12
MW47
ML25
MW50
ML24
ML23
ML22
ML34
ML33
ML32
ML31
ML21
MW48
Fe 0
PRB
ML11
MW38
MW18
MW compliance well
(5-10 ft. screen)
ML multilevel bundle
(6 in. screens)
0
10 m
MW13
Approx. scale
Groundwater
flow direction
Plating
shop
Hangar 79
FIGURE 6.1
Site map showing locations of the source, PRB, monitoring wells, and Transect 2.
the aquifer matrix to a reactive ferrous iron state, which drives the reduction
of mobile Cr VI to the insoluble trivalent (Cr III ) state.
6.3 Site Evaluation
The evaluation of the Elizabeth City PRB consisted of detailed groundwater
sampling, hydrologic characterization, and core collection and solid-phase
studies. In this contribution, we focus primarily on groundwater sampling
results and contaminant distributions. A detailed monitoring network of
over 130 subsurface sampling points was installed in November 1996 to pro-
vide detailed information on spatial and temporal changes in pore water
geochemistry and hydrology. A series of 10 2-inch compliance wells have
been sampled on quarterly, biannual, or annual basis (Figure 6.1). In addi-
tion, three detailed transects consisting of multilevel monitoring wells have
been sampled, generally on an annual basis. Here, we focus on Transect 2
(ML21-ML25; Figure 6.1), which was placed in a position to coincide with the
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