Geology Reference
In-Depth Information
b.
The velocity of groundwater from pond C to Saunders
Creek is about
11.
What techniques might be used to increase the rate of flush-
ing of the high-chloride water in the areas of contaminated
soil?
ft/day.
6.
If we divide the distance of travel (measured along a flow
line) by the rate of flow of groundwater, we obtain the travel
time. What are the travel times for water from pond C to
a.
Olentangy River:
b.
Saunders Creek:
12.
A second isochlor map, based on the March 1969 data, is
shown in Figure 15.3. A contour interval of 300 mg/L was
used. This map is useful in determining the change in conta-
mination with time. Compare Figures 15.2 and 15.3 and
describe the changes that have occurred.
7. On another map (Figure 15.2) construct contours repre-
senting lines of equal chloride concentrations (isochlors).
Use the data for October 1966 (Table 15.1) and a contour
interval of 5,000 mg/L. Consider the direction of groundwa-
ter flow when drawing these contours. Thus isochlors are
given in Figure 15.2.
13.
The shallow farm well (12 ft deep) at W-l increased in
chloride concentration between 1966 and 1969 (Table 15.1).
Has this contamination resulted from brine disposal into
ponds A, B, C, or D? Explain your answer with the aid of the
cross-section sketch (Figure 15.4), which goes from points X
to X' in Figure 15.1. Complete the water table and indicate
groundwater flow by arrows in Figure 15.4.
8.
Should the Olentangy River and Saunders and North
Creeks contain higher than normal concentrations of chlo-
ride in the vicinity of the contaminated area? Why?
9.
Wells 23 and 24 (Table 15.1) contain higher concentrations
of chloride in October 1966 than in November 1965, while
the other wells contained less. Consider your answer to
question 6b in your explanation of why this is happened.
PART B. SURFACE WATER CONTAMINATION
FROM OIL FIELD BRINES IN CENTRAL OHIO
In this part of the exercise river pollution can be traced
to techniques for disposing of saltwater (brine) that is
pumped with oil. Regulations in most areas now
require subsurface disposal of oil field brines and have
significantly reduced groundwater and surface-water
pollution.
Surface waters can be contaminated directly
through effluent discharge and surface runoff or indi-
rectly through discharge of contaminated groundwa-
ter. This exercise illustrates the effects on a drainage
basin of poor waste-disposal practices of oil field
10.
What do you think the chloride concentration of the
groundwater was before brine-pit disposal began (i.e., what
was the background concentration)?
FIGURE 15.4 Cross section from points X to
X' in
Figure 15.1.
