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 6 a.m. to 6 p.m.  Determine the required equalizing storage volume in this case.

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