Laserfiche WebLink
<br />nLI..O....UWClll... n.. <br /> <br />Excerpt from "prop. for Engineertng Services - Th.own of Lyons Water <br />. System Improvements produced by RllD, Inc., Enginee~gConsultants ~ <br /> <br />Task 3. Diversion Dam and Raw Water Intake Structure <br /> <br />Town staffhas operated the existing intake structure for many years. Initial site visits <br />and discussions with the Public Works Director have fixed the scope of the design of these <br />facilities. The existing diversion dam is to be demolished and rebuilt as a new structure. The <br />existing presedimentation basin will be cleaned and Sl1bstmtialIy modified for more efficient <br />operations. All new structures must be designed to maintain sufficiently high velocities to <br />transport stream sediments downstream through the c1iversion dam. The headworks will require <br />a trash rack and the design must exclude bedload sediments from entering the presedimentation <br />basin and grit channel. The dam structure is considered non-jurisdictional under the regulations <br />of the Colorado Division of Water Resources. <br /> <br />RED, Inc. conducted a hydrologic analysis of this potlion of North St Vrain Creek in 1991 for <br />the Apple Valley Road Bridge Project It has been determined that much of the data generated in <br />that projectwill be of use in the task <br /> <br />Allowances must also be made for: demolition of the existing structures, bypass flows, <br />. transmigration of fish, temporary intake to the raw Wllter transmission line during construction, <br />passing of flood waters and wintertime icing conditio11s. Recreational uses may also have to be <br />considered. This task is accomplished in the fono~ steps: <br /> <br />3.1 Conduct site topographic and geotechnical site SUtveys. Prepare a topographic site pIan of <br />the existing conditions, to be used in the pennitting ptocess and the final bidding documents. <br />Prepare a geotechnical report to include design crirem for the foundation design and <br />construction of a new diversion structure and reconstruction of the existing presedimentation <br />basin. Analyze existing hydrology data to determine the anticipated maximum design flood over <br />the diversion structure. Prepare hydraulic design crit~ to accomplish the functions outlined <br />above, such as allowances for sediment transfer, minimum flows and fish passage. Combine the <br />findings of these investigations and preIimiruuy design considerations in a preliminary design <br />report, to include site plan, pennitting requirements, sketch designs and opinion of probable cost, <br />for review by the town staff <br /> <br />3.2 After review by town start: prepare development design drawings (DD) of the proposed <br />improvements: diversion darn, presedimentation basin, inlet gate and high water protection <br />barrier. <br /> <br />3.3 Prepare an application for and assist the town in the processing of a Section 404 pennit for <br />construction in the river corridor. <br /> <br />3.4 Prepare final design and bidding documents (ED) for construction of the elements in subtask <br />3.1,3.2 and 3.3 above. Prepare an engineer's estimate of probable construction cost <br /> <br />4 <br />