CEE 371 

Fall 2009 
Homework #4 Water Distribution
System Storage
1. Given the hourly average demand rates shown below (in gpm), calculate the uniform 24 hour supply (or pumping) rate and the required equalizing storage volume (in million gallons). Prepare both a diurnal demand hydrograph and a “mass diagram” for the problem. Find the equalizing storage using the demand hydrograph, and confirm on the mass diagram.
12 midnight 
2000 

12 noon 
6300 
1 AM 
1900 

1 PM 
6500 
2 
1800 

2 
6460 
3 
1795 

3 
6463 
4 
1700 

4 
6500 
5 
1800 

5 
6700 
6 
1910 

6 
7119 
7 
3200 

7 
9000 
8 
5000 

8 
8690 
9 
5650 

9 
5220 
10 
6000 

10 
2200 
11 
6210 

11 
2100 



12 midnight 
2000 
2. Suppose that the supply or pumping period is
only 12 hours, from
3. Make an estimate of the total required distribution storage volume for this community. Assume that the information for part 1 is for the maximum day flow for a community of 35,000 people and that the ratio of Q max day to Q average day is 1.5 for this community. Use the population method to calculate a design fire flow and assume a fire duration of 10 hours. Clearly state your assumptions and reasoning for estimating the emergency reserve storage volume.
Assigned: 5 Oct 09
Due: 13 Oct 09