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I I I I I I I I I I I I I I I I I I I SECTION II ri prapped low flow channel will be provi ded for normal fl ows. Bermi ng along Clear Creek with rock protection for the end of berm near the Tucker Gulch channel is proposed to slow flood-waters and improve the transition of flows entering Clear Creek. SUMMARY OF SELECTED PHASE B PLAN The flood control improvements and recommendations selected by the City of Golden, Jefferson County, and the Urban Drainage and Flood Control District for Tucker Gulch and Kenneys Run are summarized in the following paragraphs. Preliminary design drawings and commentaries, located in Section IX of this report, present more detailed information regarding the selected Phase B plan, including a breakdown of estimated improvement costs for each sheet. During the Phase B study, mi nor modifi cat ions were made to the recommended pl an presented in Phase A and are di scussed in the fo 11 owi ng paragraphs. The modifi cat ions proposed do not const itute a change from the conceptual pl an presented in Phase A. . Maintenance access is proposed for the existing rock-lined channel upstream of 7th Place. Access to this reach, as well as other channel reaches, should utilize existing streets and R.O.W. where possible. Maintenance access to this reach can be incorporated in the design of a bike/pedestrian trail system being planned by the City of Golden. . Concrete grade beams are recommended for the upper reach of Tucker Gulch and the lower reach of Cressmans Gulch to stabilize the existing channels. Tucker Gulch/Cressmans Gulch . A possible realignment of Cressmans Gulch and a typical channel section are shown on the plan drawing for implementation by the developer. Other alternatives are also available with the recommended plan being floodplain regulation. . A 100-year capacity channel is proposed for Tucker Gulch from State Hi ghway #58 to downstream of 10th Street. A structural walled channel with a rock-lined bottom and drop structures is proposed, as compared to the Phase A plan recommendation for a concrete-lined channel. The plan changes were made with the approval of an advisory group consisting of staff members of the project sponsors and were recommended to avoi d problems associated with the design of a supercritical channel. The 9th St reet bri dge wi 11 also requi re replacement in conj unct i on with the channel design. The bridge replacement was not identified as a need in the Phase A study and the revised recommendation was also made with the approval of the advisory group. . Improvement of the State Hi ghway #93 cross i ng of Cressmans Gul ch is proposed in conjunction with future plans to realign the highway. Twin 66" RCPs are proposed wi th the master pl an for handl i ng the 100-year frequency flood without overtopping the highway. Alternative designs may be more desirable in realigning the highway. It is recommended that any alternative design utilize the hydrology and criteria presented in this report. . A concrete encasement is proposed to protect the Church Ditch si phon. The encasement is designed in conjunction with the first drop structure proposed downstream of State Highway #58. . The master plan includes the recommendation that floodplain regulations continue to be enforced and that the City of Golden and Jefferson County maintain their eligibility for participation in the National Flood Insurance Program. Residents and private property owners subject to existing flood hazards should be encouraged to purchase flood insurance. . A stilling area and debris basin is proposed for an area currently occu- pied by a trailer court at the Tucker Gulch confluence with Clear Creek. The design includes lowering the right bank of Tucker Gulch and re-shap- ing the upper portion of the stilling area to allow flows to spread. A Table 11-1 provides a summary of the estimated total cost of improvements for the Tucker Gulch and Cressmans Gulch drainageways. 11-1