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The a~ove list of damayes haw;: bee" converted into dol lars and userl irt artalyzingbenefits for the fol10"ingalternative treatmefit plans. (See StructlJral'1easuresandComparisonofAlternativestables). This alternathewould InclUde no improveloents on the West Basin because there appears to be no sigriificanc flOOd damages alo"g this cnanne 1. Alternathe No.1 This alternative considers: (1) collecting runoff from the East B~sin drainage above lower Cactus Valley DitCh and using a drop inlet spillway to pass this floodwater under the ditch to a stable outlet downstream, (2) diverting Sixteenth Street Basin flows to the east boundary of Silt to ~ collection area and using a drop inlet spillway to pass this ~ater under Grand Avenue, under the lower Cactus Valley DitCh, and under US Highway 6 to d location where the flows can be outletted to a stable grade, (3) collecting Seventh Street B~sin flo~s at the mouth of the canyon north of to~n dnd using a drop inlet spillway and pipe to carry the flows to the lower Cactus Valley DitChwhereitwil1 outlet irttotheditch, (4) buildirtgup First Street and County Road 231 to divert First Street Basin flo~s that exceed culvert and channel capacities to an overflow channel. ThiS overflo>; Channel leads to an adjacent drainage to the west. The overflow would be collected at the lo~er Cactus Valley Ditch into a drop inlet spillway that would pass under the ditch aod continue to ao area below the small pond ~t City Park near Dogwood Drive, (S) liningthelowerCactusValleyOitcn from Seventh Street to the channel we~t of town that leads to the City Park referred to irt Item 4 above. The li ned ditch ~ould handle flOOd flows from Seventh Street Basin as ~ell as i rrigation f1o~s. flitch f1o~s greater thao 50 cfs would be spi lIed into the Ci ty Park d rai nage becalJ~e of the 1 imited capacity ot an i averted siphon structure a Short distance downstream. Alternative No. 2 This alternative would be the same as Alternative No.1 with the following exceptions: 1. Item number 3 ~ould include a continuatiort of the pipe under the lower Cactus Va 11 ey Oitch and on south to the ra il ro~d. A pi pe would be jacked under the railroad to allow discharge at a stable outlet above 1-70. 2. Item number 5 (ditch lining) would not be included. AlternativeNQ.3 Thi S a 1 ternat i v.. \oIOul d i nc I wI.. Ii oi ng the Lower Cactus V~ 11 "y Oi ten from Ninth Street to a spill location at the City Park Drainage. The capacity of the lined ditch would be sufficient to c~rry flOOd flo~s from Seventh Street Basi" and normal i rri gation fl o~s (50 cfs). Some dike work would also be neeessary at Couoty Road 231 on First Street Basin similar to Item No .4in Alternative No. I. There would be no improvements to West Basin, Sixteenth Street Basin, or East Basin in this alternative. - 24 - -23-