Water Source and Storage Calculations - Basic Mathematics for Water and Wastewater Operators - page 228

WATER STORAGE
Water storage facilities for water distribution systems are required primarily to provide
for fluctuating demands of water usage (to provide a sufficient amount of water to aver-
age or equalize daily demands on the water supply system). In addition, other functions
of water storage facilities include increasing operating convenience, leveling pumping
requirements (to keep pumps from running 24 hours a day), decreasing power costs,
providing water during power source or pump failure, providing large quantities of
water to meet fire demands, providing surge relief (to reduce the surge associated with
stopping and starting pumps), increasing detention time (to provide chlorine contact
time and satisfy the desired contact time requirements), and blending water sources.

WATER STOR AGE CALCULATIONS
The storage capacity, in gallons, of a reservoir, pond, or small lake can be estimated
(see Figure 15.3) using Equation 15.15:

7.48 gal/ft 3

Capacity = Avg. length (ft)Avg. width (ft)A × × vg. depth (ft) × (15.15)

■ Example 15.17
Problem: A pond has an average length of 250 ft, an average width of 110 ft, and an
estimated average depth of 15 ft. What is the estimated volume of the pond in gallons?

Solution:

3

Volume = Avg. length (ft)Avg. width (ft)Avg × × .. depth (ft) × 7.48 gal/ft

3

= 250 ft × 110 ft × 15 ft × 7.48 gal/ft = 3,085,500 gal

Top view of a pond

Average Length (feet)

Average Width (feet)

FIGURE 15.3 Determining pond storage capacity.