Environmental Engineering Reference
In-Depth Information
N
3
1
7
3
4
512
505
514
513
3
4
2
2
2
5
1
1
509
3
506
7
6
516
510
508
511
507
#
Injection Well
#
Recovery Well
#
C-well (1 inch PVC)
Monitoring Well (2 inch PVC)
2
Figure 5.5
Well locations at the former Sage's Dry Cleaner site in Jacksonville, FL.
5.3.2.5 Groundwater flow characterization
Characterization of the groundwater flow was initially conducted by LFR
Levine Fricke (1997a, 1997b). Groundwater flow direction in the surficial
aquifer was generally westward toward the St. Johns River. Groundwater
elevations monitored over the project period showed similar results (Figure
5.6). The flow in the adjacent drainage canal is to the north, which may
impact groundwater flow. The relationship of the drainage canal to ground-
water flow in the surficial aquifer was unclear from the initial investigation.
During periods following major rainfall events, the depth to water table
would be expected to decrease, and the drainage canal could potentially
impact local groundwater flow direction. The hydraulic gradient during the
project period ranged from 0.0025 to 0.006. A slug test conducted by LFR in
MW-4, which was screened from 7 to 10.1 m bgs, gave an average hydraulic
conductivity of 3.2 m/day. Slug tests conducted in MW-1, MW-2, and MW-3,
which were screened from approximately 3 to 6.1 m bgs, gave an estimated
average hydraulic conductivity of 6.1 m/day. The results from this study
were used in the design of the solvent extraction system.
In July 2000, an electromagnet borehole flowmeter was used by the EPA
to define the relative hydraulic conductivity distribution of aquifer materials
screened by well MW-516 (Acree, 2000). The electromagnetic borehole flow-
meter is a commercially available system manufactured by Tisco, Inc., and
consists of a 1.25-cm-ID (inner diameter) downhole probe, a 2.5-cm-ID down-
hole probe, and an electronics module. The investigation was conducted
using procedures based on the methods of Molz et al. (1994) and Young et
al. (1998). Flow rate measurements using the electromagnetic borehole flow-
meter were made under ambient and constant-rate pumping conditions at
