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HomeMy WebLinkAboutBURNS RANCH AT QUAIL RIDGE RF CLUSTER PLAN AND RF SUBDIVISION REVIEW - 23-90B - CORRESPONDENCE - CITY STAFFCity of Fort Collins July 19, 1990 Utili:'! sen —S Water & lVastewatei M E M O R A N D U M t iZ 5�'EN TO: Tom Peterson, Director of Planning FROM: Roger Buffington, Systems Engineer THROUGH: Mike Smith, Director of Water and Wastewater Ut'lities Jim Hibbard, Distribution & Collection Manager RE: Water Service above Elevation 5200 1,c.? s-IGTS TC N 6 In response to the recent development proposal received from Rex Burns and to discussions with Planning Department staff, the Water and Wastewater Department has completed an evaluation of providing water service above elevation 5200. For the purpose of this proposed development and the surrounding area, the scope of this analysis has included the area between Harmony Road on the south and County Road 42C on the north. A determination has been made regarding the water storage facilities which would be required, and the overall feasibility of providing service in this vicinity has been reviewed. One of the initial considerations in evaluating a possible third pressure zone is the band elevations to be served by the system. The present Foothills Zone has the capability of adequately serving to Elev. 5200. If a typical pressure range of 45 to 100 psi is used, the corresponding elevations for water service in the third zone could extend from 5200 to 5315. This would maximize the utilization of that system. In this case, the band of service is limited by City Code to Elev. 5250. This creates a situation that utilizes less than half of the potential of a third pressure zone. From a design standpoint, this is inefficient and increases the cost per unit of development being served. For the situation under study, the potential development area which is between Elev. 5200 and 5250 and which lies within the City's water service area is quite limited. On the west, it is bordered by the Pineridge Open Space and the Dixon Reservoir. To the south, the boundary between the City and the Fort Collins - Loveland Water District is located at Horsetooth Road. The remainder of the area is relatively small with little or no chance of expansion. (See attached map.) P.O. Box 580 • I twt Collins, CC) 80522-0580 • (303) 221-668I L] LJ Water Service July 19, 1990 Page 2 of 3 above Elevation 5200 The remaining area which has development potential is approximately 60 to 70 acres. Planning staff has indicated that portions of that area may never develop; however, from the standpoint of water supply needs, a conservative approach has been taken in assuming that 70 acres will be developed at 1 unit per acre. Alternatives for providing water service which have been reviewed include the following: Alt l: In -line booster pump station near Quail Hollow to increase the pressure for the potential development area. Alt 2: Pump station and water storage reservoir to meet domestic demands and provide typical fire flows and fire storage. Alt 3: Pump station and water storage reservoir to meet domestic demands, to provide capacity for residential fire sprinkler systems and to furnish a reduced fire flow and fire storage. The in -line booster pump alternative was eliminated from consideration for two major reasons. First, it is not able to provide the level of reliability to meet the Utility's customers expectations. Secondly, this alternative will not meet Poudre Fire Authority's requirements which state that all developments served by municipal or district water distribution systems or located within one mile of systems capable of supplying required fire flows shall have fire hydrants installed in the development. The minimum fire flow required from these hydrants is 500 gpm if residential fire sprinkler systems are provided and 1000 gpm with no sprinkler systems. (These are minimum requirements and may vary depending upon density of the development.) Alternative 2 or 3 will provide an adequate water supply system and will meet PFA requirements. The only difference in the alternatives from a water supply standpoint is the volume of storage which is required. In order to provide fire protection storage and a level of reliability similar to the main distribution system and the Foothills Pressure Zone, the total water storage requirements and the preliminary cost estimates for the water storage reservoirs and pressure zone pump stations are as follows: Storage Volume Preliminary Requirement, gallons Cost Estimate Alternative 2 170,000 $400,000 Alternative 3 110,000 $310,000 The high cost for providing the water storage and pumping system for a third pressure zone is caused by the following: It is very costly to construct relatively small storage reservoirs as compared to large reservoirs which can take advantage of the economies of scale. 0 • Water Service above Elevation 5200 July 19, 1990 Page 3 of 3 2. In order to provide adequate pressure at Elev. 5250, the tank must be constructed at a site with an elevation in excess of 5355. As a result, access will be more difficult and construction more costly. In addition, this elevation requirement causes the tank site to be a significant distance from the developed area which will add substantially to the water main costs. These costs cannot be determined until a tank site is identified. 3. Construction of a tank in the Foothills is more costly than typical construction because of the need to blend the facility into the surrounding landscape while still providing adequate security in a remote area. These cost estimates do not include the cost of land for the storage and pumping facilities nor the cost of the water mains to interconnect the existing water distribution system, the pump station, the development area and the water storage reservoir. Due to the topography in the area, it appears that at least a half to three -fourths mile of water main will be needed; therefore, the water main costs will be substantial. In addition to the high capital costs to initially establish this pressure zone, the Water Utility has other concerns regarding the development of this system. The ongoing operation and maintenance effort to maintain any pressure system with a level of reliability expected by water customers creates a significant 0 & M expense. When this level of cost is applied to a relatively small system, the unit cost per 1000 gallons of water delivered becomes unrealistically high and difficult to justify. Small systems also cause concerns regarding water quality. In this case, the volume of storage for fire protection is a major portion of the total storage. This creates a situation in which there is very little circulation and turnover of the water in the reservoir. These circumstances often lead to very low or nonexistent chlorine residuals which will not meet water quality standards. For the reasons outlined above, the Water Utility strongly suggests that alternatives other than the establishment of a third pressure zone be pursued. These alternatives might include obtaining water service from the Fort Collins - Loveland Water District which has a tank at a higher elevation than the City's Foothills reservoir or not allowing development above the elevation which can be served by the Foothills Pressure Zone (Elev. 5200). Attachment cc: Rich Shannon Ken Waido Kirsten Whetstone Sherry Albertson -Clark Roger Frasco � • , � \. ;I' ,� /. � �\. b 87 •PRO •il: � .� 1 . 50 HY hes_ 1 � \ ✓' d J! J / \ C snNo S ,um 21� , ^� lG,ano J_ IDriyon� " � � I DiwnG Von� 4 ta'oh1 --- •-w _...�� Q _ 5;44 KET�°�° DRAKE RD RAKE rz j AIZEAS 7 \ v e s, s`.. �V1,11yv vv /p; N \J f b CITif i0F F©RT CAtt�IdS FC INEI2IDGE OPEN SPACEWO OOT14 � S�-VICE .D►STi2JCT BOUN[ 0 �.� 32 33 c, a v �qI ;, I� SS s�lv a,t' r j• Dam r� v ' l f ��— c-+ r� �L2 27-