Civil Engineering Reference
In-Depth Information
OVERFLOW ELEVATIO
N
PUMP
OFF
OPERATIONAL
STORAGE
PUMP
ON
EQUALIZING
STORAGE
EMERGENCY
AND/OR
FIRE STORAGE
DEAD STORAGE
DISTRIBUTION SYSTEM
SOURCE OR
BOOSTER PUMP
Fig. 27-1.
Storage components (Courtesy of Washington State Health Department)
curve and above the line representing average hourly flow rate on the maximum day.
Assuming that the source of supply meets the average flow demand during the max-
imum day, the shaded area below the average flow line would equal the unshaded area
under the curve above the average flow line. With this diurnal demand curve, approx-
imately 22 percent of the water volume used on the maximum day would need to be
provided in flow equalization storage to meet peak demands. This is represented by
the ratio of the shaded area to the total area below the average flow line. For example,
if the maximum daily demand for this system were 10 MG (38 ML), then 0.22
10
MG
2.2 MG (8.3 ML) of equalization storage would be required. This example
calculation assumes that the source of supply operates for 24 hours per day at the
average daily demand rate. Restricting water supply facilities to less than 24 hours of
operation would require additional storage volume or a higher-capacity source of sup-
ply to meet peak demands.
