Page 196 - Water and wastewater engineering

WELLS 4-51

40.0 1.11
60.0 1.17
100.0 1.28
120.0 1.31
180.0 1.39
240.0 1.45

4-7 DISCUSSION QUESTIONS
4-1. An artesian aquifer is under pressure because of the weight of the overlying geologic
strata. Is this sentence true or false? If it is false, rewrite the sentence to make it true.

4-2. For the following well boring log, identify the pertinent hydrogeologic features. The
well screen is set at 6.0–8.0 m, and the static water level after drilling is 1.8 m from
the ground surface.
Strata Depth, m Remarks

Top soil 0.0–0.5
Sandy till 0.5–6.0 Water encountered at 1.8 m
Sand 6.0–8.0
Clay 8.0–9.0
Shale 9.0–10.0 Well terminated

4-3. For the following well boring log (Bracebridge, Ontario, Canada), identify the per-
tinent hydrogeologic features. The well screen is set at 48.0–51.8 m, and the static
water level after drilling is 10.2 m from the ground surface.

Strata Depth, m Remarks
Sand 0.0–6.1
Gravelly clay 6.10–8.6
Fine sand 8.6–13.7
Clay 13.7–17.5 Casing sealed
Fine sand 17.5–51.8
Bedrock 51.8 Well terminated

4-4. Sketch the piezometric profiles for two wells that interfere with one another. Well A
3
3
pumps at 0.028 m /s and well B pumps at 0.052 m /s. Show the ground water table
before pumping, the drawdown curve of each well pumping alone, and the resultant
when both wells are operated together.

4-8 REFERENCES

AWWA, 1999 Design and Construction of Small Systems, American Water Works Association,
Denver, Colorado.
Boulton, N. S. (1954) “The Drawdown of Water Table under Nonsteady Conditions near Pumped Well in
an Unconfined Formation,” Proceedings of Institute of Civil Engineering (London), vol. 3, part III,
pp. 564–579.