1997-02-26 - Laserfiche WebLink

Home Browse Search

2010 346,667 480,000 480,000 500,000 2015 376,333 480,000 480,000 500,000 2020 407,667 480,000 480,000 500,000 m Assumes that ISO fire flow requirement of 1,000 gpm for 4 hours does not change. A new 400,000 gallon tank is projected to be needed well before the year 2000, which is reflected in the projected total storage volume in Table 6 -8. By the summer of 1997, the peak hour storage requirements are anticipated to exceed the available 100,000 gallon storage capacity. Since the lead time for water towers is over 42 weeks, we recommend that the City proceed with construction of the proposed new tower. The City is considering the construction of a new tower and an interconnection with the City of Lino Lakes to augment its storage and fire fighting capacities. 6.5 DISTRIBUTION SYSTEM The adequacy of a distribution system depends not only on the size of watermains but also on location and capacity of production, treatment, and storage facilities for the system. Watermain sizes are usually determined by fire demands, since fire demands result in much higher flows than other demands. Watermains must be sized to supply large demands locally and transfer water to areas more remote from supply and storage facilities. As Centerville grows, the maximum demands of the individual service areas will become more significant, relative to the fire demands. The Centerville water distribution system has been modeled with the CYBERNET computer model to aid in evaluating its current adequacy and to design future improvements. The evaluation of the existing watermain system was based on the American Water Works Association's Distribution Requirements for Fire Protection. The primary evaluation of watermain was made under peak hour demand conditions. The evaluation also included maximum day demand plus fire flow demand. In assessing model results, the predicted conditions for each individual watermain were evaluated in order to assess the performance of the watermain. The head loss per watermain was examined. The velocity predicted for each watermain and the head loss per 1,000 feet were also examined. Generally, watermains are considered potentially deficient, or most - limiting segments, if they are predicted to have any of the following conditions: • Velocities greater than 5 feet per second (ft/s), • Head losses greater than 10 ft/1,000 ft, or • Large- diameter pipes (16 inches or greater) having head losses greater than 3 ft/1000 ft. Watermains become limiting factors in delivering water at acceptable pressures to the extremities of the system when velocities approach 5 ft/s. As head losses in a watermain approach 10 ft/1,000 ft, a substantial loss of pressure occurs in that length of watermain. Watermains with head losses exceeding 10 ft/1,000 ft are generally a contr factor to inadequate system pressures. The ultimate test of water distribution system adequacy is the pressure at the point of delivery. CWP- 260A.080 6 -6 260 -080-25