12-18-2013 Council Agenda - Laserfiche WebLink

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Available Fire Flows For the purpose of review the modeling was completed at the southern most hydrant with the water tower approximately half full and at peak day demand throughout the system. The results were a static water pressure of approximately 70 psi and a fire flow of 2,500 gpm at a residual system pressure of 20 psi. It should be pointed out that a residual system pressure of 20 psi is the recommended minimum residual pressure allowed in a system. It is our understanding that the two City engines can utilize up to 2,000 gpm each and the one aerial truck up to 1,000 gpm. The 2,500 gpm fire flow would need to be shared among the equipment as any larger demand on the system could result in less than 20 psi of residual pressure in the system. The fire flow volume could be increased to the site if the current 8 -inch dead end main were looped back to the 12 -inch main in Country Drive. We estimate looping of the 8- inch main would increase the fire flow by about 700 gpm up to a total of 3,200 gpm. Required Fire Flow The ISO is the organization that is typically used or sited for standards of fire protection. They provide formulas and guidance on recommended fire flows for commercial buildings based on several factors. However, for this property a significant portion of the concern is the outdoor storage element and the increased fire hazard it represents and unfortunately outdoor storage areas are not addressed in the standard ISO formulas. We talked to the State Fire Marshal office for guidance on calculation of a required fire flow and their recommendation was to have a fire protection engineer review the site and provide a recommended fire flow volume taking into account the stored material type, amount, and location. Recommendations Based on a review of the hydrant spacing and the proposed increased use on the west side of the property it may be beneficial to install a hydrant on the west side of the existing building. This would provide the fire department a water access point west of the building to allow more options for fighting a fire in the storage area stakes and provide standard coverage of most of the area west of the building. The City's Fire Chief should comment on the need and location of the hydrant. At this time we do not have sufficient information to make a recommendation on the need for looping of the watermain for additional fire flow. We would recommend the City require the applicant to have the site reviewed by a fire protection engineer to determine the needed fire flow volume for the site including the storage area. Once that information has been provided a decision on looping of the watermain could be made. If you have any questions concerning this information, please call me at (763) 780 -0450. 10062 Flanders Court NE — Blaine, MN 55449 — Ph: (763) 780 -0450 Fax (763) 780-0452 Z :PROD \120000E • little Canada General \2013\Memo-120613 -Fire Flow 3213 Country Orive.doe 25