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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 I <br />I <br />I <br />I I <br />I <br />I <br />I I <br />I <br /> <br />IV. EXISTING CONDITIONS <br />A. ANALYSIS OF EXISTING PUMPS <br /> <br />Pumping of stormwater is normally difficult because of the relatively <br />fast time to peak and the large volume of water. Pumps must be large <br />enough to remove the water at the same rate as the inflow or ponding <br />will occur, flooding streets, buildings, and property. <br /> <br />The city has in the past attempted to relieve the flooding near the <br />Alamosa Inn (Basin I) by installing two pumps in Blanca Avenue near <br />Highway 160/285. One of the pumps is currently inoperable and the <br />other pump leaks such that the "dry well" side is continually flooded, <br />making the second pump inoperable without special assistance from the <br />~~intenance Department. These pumps have a capacity of 3,000 gpm (7 <br />cfs) each. The lOO-year discharge tributary to this point is 100 cfs. <br />In comparing these numbers, it is obvious ponding occurs at this loca- <br />tion as the pumps cannot keep up with the anticipated runoff. Even <br />for the lower frequency storms, ponding occurs. It would not be prac- <br />tical to replace these p~mps as the discharge line is too small and <br />would have to be replaced. Since one of the alternatives evaluated <br />creates a new discharge line and can flow by gravity, it is not rec- <br />ommended to upgrade the existing pumps or add new. pumps. Until new <br />systems are constructed, it is recommended to keep at least one pump <br />working to drain this area. <br /> <br />Another pump was installed near the existing discharge point of the <br />line from the Alamosa Inn near El Rio Drive at the Rio Grande River, <br />Basin II. The pump has been inoperable for several years because of <br />an electrical failure resulting from a lightning strike. The pump <br />capacity is 4.5 cfs. Since the pump is not located in a sump area, <br />it can pump only what is pumped from the Alamosa Inn. Thus, the <br />capacity of the overall system is too small to be helpful during a <br />flood, if operable. It is recommended the pump not be repaired or <br />upgraded as the recommended alternates use a different discharge <br />poi nt. <br /> <br />-16- <br />