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HomeMy WebLinkAboutBUCKING HORSE PARK - BDR210011 - SUBMITTAL DOCUMENTS - ROUND 3 - SUPPORTING DOCUMENTATION (2)Date: 3/8/2022 To: Matt Simpson Wastewater Engineering – City of Fort Collins From: Clark & Enersen Regarding: Water Meter Service Verification The domestic water meter at Bucking Horse Park Restroom has been sized down from the maximum peak flow after discussions with Craig Kisling and the City of Fort Collins Park Planning and Development (FCPPD) department about the maximum occupancy, maximum usage and diversity. The FCPPD requested the system be sized to utilize an ¾” water meter on site. FCPPD instituted this changein order to avoid increasing the size of the water meter. The FCPPD deemed the cost associated with increasing the water meter to be prohibitive to the project given the available budget.The implications of this decision are that, in the event that all restroom fixtures are operating simultaneously at maximum possible volume†, the building will only operate fully for a short time. Clark & Enersen informed the FCPPD of these implications, and the FCPPD stated that this occurrence is very unlikely to happen over the life of the building and for Clark & Enersen to proceed with this assumption.† Maximum possible volume assumes all fixtures operating continuously resulting in 52 gallons per minute for maximum load. Though these criteria are highly improbable to ever arise in normal building operation, this is the design standard Clark & Enersen follows to ensure no possible situation arises which will overtax the domestic water system. The initial assessment by Clark & Enersen, based on the Uniform Plumbing Code (UPC), indicated the need for a 1-1/2” main in the building served by a 2” water meter. This matches the design criteria of the AWWA M22 sizing method depicted on the next page. At the request of the FCPPD, Clark & Enersen provided a potentialsolution to utilize the existing service by the inclusion of a domestic water buffer tank that will offer a pressurized reserve for high-use periods. This design maintains the 1-½” supply main required by UPC 604.3 and AWWA M22 sizing method, however allows the use of the ¾” water meter. Clark & Enersen advises against any design which does not allow for maximum possible design condition, and has informed Fort Collins FCPPD that utilizing this strategy will result in such a condition. Despite this, Clark & Enersen believes thatthis system will perform as designed if the frequency of use as defined by FCPPD is accurate. Clark & Enersen does not assume responsibility for any system deficiencies in instances of use beyond the usage criteria provided by the FCPPD. The following is a summary of the capabilities of the system. Design with buffer tank: In order to assess the system to ensure that the water service meter is overloaded, Clark and Enersen has established the following conditions and assumptions based on guidance from the FCPPD: Minimum system pressure: 40 PSI – The flush valves only require 25 psi to operate, however 40 psi creates a contingency to ensure that the fixtures will function properly. Water supply from meter: Per the Fort Collins Department of Waste and Water Management, the ¾” meter proposed will allow 30 gallons per minute of water at 120 PSI. System Drawdown - the available volume in the buffer tank before tank pressure equalizes to system pressure:Buffer tank volume: 53 GallonsMinimum system pressure: 40 PSIGTank Pre-Charge: 80 PSIGTank can provide 26.5 gallons of water at a maximum of 25 GPM System Capabilities:After one instance of simultaneous use of all fixtures, the system will require 20 seconds to fully recover the volume in the buffer tank without flushes or lavatory use occurring. If each toilet is used once every 5 minutes, and lavatories run 20 seconds per flush, the system will operate sustainably with the buffer tank refilling between uses.If the system was upsized to a 1” water meter, operating at 50 GPM, the system would operate for 15 minutes at peak volume, or indefinitely if lavatories are only used 75% of the time instead of continuously.