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COMMENTARY SHEET 20 OF 45 STATIONS 1232+00 TO STATION 1292+00 REACHES5AND6 mended plan call s for the channel to be lowered, the tne~ of the sl ope~ should be protected with riprap. In order to acco'lJllodate the lowered chaMe 1 a 16- inch water 1 i ne at Stat i on 1274 woul d be re' o;;~ted or lowered. This reach includes rail yards and industrial properties. Flood problems in this reach are confined mainly to the right overbank area between Inter- state 25 and Speer Boulevard, an area of approx1mately2oo acres, which receives flooding from direct overflow fr~ the South Platte River and from water whiCh f10ws underneath Interstate 25 starting at 13th Avenue. This reach also includes Confluence Park and Shoemaker Plaza, a popular location for outdoor events. The first priority in this reach 1sto relocate the Farmers and Gardner's diversiondil/ll. Follow1ngthat it would be necessary to lower the existing dam and remove the material from the ehannel between the existing dam and thereloeatr.dd3r11. The next priority is to re<nove the bench area between 15th Street and 16th Street. Therecommende<l improvements on this Sheet will, howf'ver, be of limited value until the improvements on Sheet 19frOUl Station 1292 to 13th Avenue are completed. The recommended plan for this reaCh is limited structural improvements. Between 16th Street and 15th Street On the right bank ahenchareashould be removed. The Farmers and Gardnersdiversion structure should be relo- cated upstream 800 feet and the exi~ting dam replaceM with a low dam 3 feet high and ~ mod i f i ed boat chutf'. Both dams shoul d be des igned to prov ide the sound of falling water to muffle the sounds of traffic On Speer Bo ule- vardduringevents at Conf1uence Park. Upstream of the lowered confluence dam the channel bottom would be lowe~ed 5 feet underneath Speer Boulevard and the right bank underneath Speer Boulevard placed On a steeper land- scaped slope. The relocated Farmers and Garnder's diversion dam will be at Station 1262 with a crest length of 820 feet including the boat chute. This boat chute will tie into the "lOdified boat Chute at the lowered con- fl uence dam providing a total boat. chute lengt.h of n..~rl y ],000 f"..t. From Station 1262 to Station 1292 the left bank should r,",TIain undisturbed. The right bank should be benched 150 feet from the existinq bank. Thebench elevation on the right bank should he 2 feet above the crest of the relo- cateddam to provide direct access to the river. A low area of 18 acres ...ilt remalnbelo...t.he loo-year flood elev.tionwith the implementatlonof thl s pl an which would have to be fi lled to two feet above the 100~Yf'ar floodelevat1onb,.foredevelopme"tshouldnc-cur. Fill material ,nay not be ta~en from tne improved ri ver cn~nne 1 . In those areas where the rec-om_ The dam lowering and construction of the new dam upstream of Speer Boule- yard has s i gni f ieant ramHi c~t ions for both flood contro 1 and recreat iona 1 activities. Oesign is a major undertaking which will require adf'quate public review and COlTlnent. landscape design is of great signHicanceof the final project suitabi 1 ity. Hydr~ul ie model1 ing is recommended for thf' dam and boat chute. Ascale'llodel Shou1d be constructed and approved by the Greenway Foundation and the Denver Parks Oepartment. The floodplain management strate9Y for this reach is to require enforcement of fl()QMpl11n manag~ment rf'9'jl at;on~. COST €STI~ATE SHEET 20 OF 4~ SOUTH PLATTE RIVER STATIO~ 1232+00 TD STATION 1292+00 CONSTRUCTION -_._~.._---_._- Tota1constrOJctioncosts P,~17,444 35,000 '150.667 2,<)03.111 870,933 9rdioag~ improv~pnt costs Street crossinq costs Utility rplocation costs Eogineering and contingp~cips (30% of total construc'ioncnSI<) Pmrprt.y MI)"i<itinn 750.000 TQTAl IMPROVEMENf COSTS 54,524,044 Operat10n and Maintenance $35,2!l2