Page 102 - Water and wastewater engineering

GENERAL WATER SUPPLY DESIGN CONSIDERATIONS 2-45

a plot on probability paper. Using the plot, write a short summary report for your
supervisor that discusses the following:

• A general description of the behavior of the data.
• Your impression of the degree of difficulty in operating the plant and the need
for operational flexibility.

• A recommendation regarding further data analysis.

Daily Turbidity for the Alma River, January, 2005
Day Turbidity, NTU Day Turbidity, NTU
1 11.50 17 8.47
2 5.53 18 7.10
3 7.40 19 6.47
4 5.83 20 3.77
5 3.35 21 3.60
6 2.80 22 2.65
7 3.00 23 2.77
8 3.20 24 2.63
9 2.75 25 2.30
10 2.47 26 2.10
11 1.95 27 2.03
12 4.00 28 2.10
13 63.67 29 1.95
14 59.60 30 2.15
15 24.33 31 2.00
16 12.70

2-9 DISCUSSION QUESTIONS

2-1. Your design office has been contracted to design a municipal well field for a small
village. The planning meeting has yielded the following information: no federal
or state money will be involved in the project, the bond rate is 6%, the population
growth rate is negligible. What design period would you recommend to the client?
Explain your reasoning.
2-2. Explain why a favorable yield analysis alone is not a sufficient reason to select a
surface water supply.
2-3. An intern has asked why a unit demand of less than 440 Lpcd was selected for a
village of 2,000 in the upper peninsula of Michigan. Explain why. Would your
answer be different if the village was in the southern half of Arizona? Why?
2-4. Can a well fail without “going dry”? Explain.
2-5. A probability plot of turbidity for a surface water results in a very steep slope. What
does this imply for the difficulty of operating the plant?