Environmental Engineering Reference
In-Depth Information
N
Ground Water
Flow
DNAPL Source Area
Target Zone
Drainage
Canal
0
20
40
60
80 Ft.
Figure 5.6
Groundwater elevations at the Sage's site on September 22, 1999, showing
groundwater flow to the west toward the drainage canal.
a measurement interval between 15 and 60 cm within the well screen. The
1.25-cm-ID probe was used for flow measurements under ambient conditions
and the 2.5-cm probe was used for measurements under pumping condi-
tions. The test was performed at a constant pumping rate of 8.8 l/min and
repeated at a rate of 4.0 l/min. The rates were chosen to induce sufficient
flow from each test interval with negligible head loss across the 2.5-cm-ID
downhole probe. Measurements of vertical flow rates under ambient and
constant-rate pumping (induced flow) conditions were analyzed using meth-
ods described by Young et al. (1998).
The estimates of hydraulic conductivity for this test represent averages over
the measurement interval, which was between 15 and 60 cm within the well
screen, and are dependent upon the interval thickness. The data collected indi-
cated that relatively conductive materials were present from the water table to
a depth of approximately 7.9 m bgs at this location. Materials of lower hydraulic
conductivity were present below this depth. Drawdown in adjacent monitoring
wells was measured during the constant-flow-rate extraction test performed
for the flowmeter survey, and these data were used for estimation of the hydrau-
lic conductivity of the aquifer materials. The methods of Neuman (1975) were
used to estimate the hydraulic conductivity using an aquifer thickness of 9.1
m, which corresponds approximately to the interval from the water table to the
depth of the well screen. These estimates of aquifer hydraulic conductivity
