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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Table 8 also shows that residual pressures at these same hydrants fall below 20 psi at relatively <br />low rates of hydrant flow. The ISO, the Uniform Fire Code (UFC), and other references cite 20 <br />psi as the minimum value of residual pressure which should be sustainable at the hydrant under <br />fire flow. <br /> <br />Fire protection deficiencies were also cited by the ISO with respect to water supply. The 400,000 <br />gallon storage tank has inadequate volume to support a 3500 gpm fire flow for a 3 hour duration <br />during maximum day demand conditions, as required by both ISO and UFC. Based upon <br />hydraulic modeling results, which allowed system demand and fire flow to be delivered from <br />both storage and the treatment plant, a stored fire volume of 560,000 gallons would be required <br />to fully support the 3500 gpm/3 hour fire flow, A storage deficiency of 160,000 gallons is <br />indicated. <br /> <br />As shown in Figure 3, the existing storage tank is connected to the lower pressure zone (pressure <br />Zone 1), severely impacting the value of the storage tank to the upper pressure zone. A bypass <br />around the PRY is available, but must be manually opened. Even when opened, for example <br />during an upper zone fire event, the tank can provide only minimal support due to its relatively <br />low elevation. <br /> <br />B. System Operations & Maintenance <br /> <br />The need to replace the existing storage tank with a new tank is also justified due to operations <br />and maintenance concerns. The steel walls of the tank are corroded and are leaking in numerous <br />places. The tank supply main is an old wood stave pipe which is also suspected of leaking. The <br />difference between water production and sewage flow for 1994 is approximately 38%, based <br />upon meter data of both flow streams, While some of the flow differential is undoubtedly due <br />to irrigation, water loss through pressure main leakage is likely a significant conhibutor to water <br />loss from the system. Although no leakage studies have been performed to quantify the losses <br />resulting from the poor condition of the tank and supply main, the fact that most of town's <br />distribution mains over the past decade have been replaced with modem ductile-iron pipe and <br />fittings, suggests that the remaining sections of wood pipe are most likely the source of water <br />system losses. <br /> <br />Elimination of the existing tank and wood stave tank supply main will be accomplished through <br />the water system improvement project. Replacement of the tank, wood stave tank supply main <br />and the other wood stave pipe segments should significantly reduce water loss. <br /> <br />Town of Minturn Water System Upgrade Project, March, 1995 <br /> <br />17 <br />