FLOOD08407 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I the purchase of public right-of-way in flood prone areas whenever such procurement becomes feasible. It is recommended that the channel be inspected, and any necessary repairs made on a regular basis and after all significant storms. Particular attention should be paid to those items listed under Operation and Maintenance Requirements of this Chapter. Debris, including trash, uprooted vegetation, and other material, should be removed during flood season to insure proper functioning of the channel. A venues currently exist whereby county governments have the authority to remove obstructions that constitute flood hazards in channels whether or not the channel flows through a public right-of-way. Article 30-30-102 from the State of Colorado Revised Statutes (1973) specifically outlines this mandate. In particular, Subsection (1) of this section states: "The board of county commissioners of each county shall have authority within its respective county, for flood control purposes only, to remove or cause to be removed any obstruction to the channel of any natural stream which causes a flood hazard, and for such purpose only the board of county commissioners shall have a right of access to any such natural stream, which access shall be accomplished through existing gates and lanes, if possible. Such authority includes the right to modify existing diversion or storage facilities at no expense to the diverter of a water right, but it shall in no way alter or diminish the quality or quantity of water entitled to be received under any vested water right." Implementation The Flood Control Plan for Little Dry Creek will provide protection to area residents and businesses from recurrent flooding. Because the drainage basin is urbanizing rapidly and creating a significant increase in storm runoff, it is recommended that the final design and construction of the proposed channel improvements begin immediately upon the availability of funds and the responsible maintenance of the channel commence and be carried out regularly. The expeditious implementation of the proposed plan will, of course, depend on the availability of funds for land acquisition and channel improvements. Because of the economic and jurisdictional considerations involved, it is recommended that the proposed program be undertaken in steps, Upstream improvements would be of little use if existing downstream channel conditions are such that flow is restricted, causing water to back up. Therefore, initial improvements on the main stem of Little Dry Creek should begin at the confluence with Clear Creek and proceed upward through Westminster. After the design is finalized and exact right-of-way requirements determined, priority should be placed on the acquisition of the necessary land to avoid construction delays. The construction of the channel improvements in a majority of Reach 1 in Adams County is to be a condition of developing the adjacent lands. v - 4 Implementation of the Shaws Heights Tributary improvements should begin with the modification of the detention pond and associated outlet works just east of U.S. 36. The improvements here will require the least amount of capital outlay while yielding the greatest flood damage reduction. Above and below the reservoir, the improvements are independent, and can be constructed exclusive of one another. Ideally though, the reshaping and seeding of the channel through the proposed Wolff Run Park should be performed concurrently with the park improvements. The detention pond east of Lowell Boulevard on the Shaw Heights Tributary must be built in conjunction with the construc- tion of the 10-year storm sewer system downstream, since the pond enables a reduction in the storm sewer pipe sizes. The channelization proposed for Tributary "B" immediately above Lake Arbor can be delayed until development of the adjacent innundated area appears imminent and made a part of development requirements. The culvert modifications under Wadsworth on tributary "C" and enlargement of the channel downstream from Lake Arbor are both independent of all other improvements, and can be built when funds become available. Cost Estimate For the selected flood control plan outlined in this report, the costs for constructing the respective facilities have been estimated using current real estate values, material prices, and labor rates. The unit prices used in the preparation of the cost estimate are listed in Table V-2. Also included in the cost for the selected plan is the estimated annual operation and maintenance expenditures associated with each type of flood control facility, Table V-3. For purposes of obtaining total initial improvement costs, the annual costs were capitalized over a 50-year period using a 6-3/8 percent interest rate. The cost estimate for each improvement was categorized into the following divisions: channel improvements, street crossing improvements, land acquisition costs, utility relocation costs, contingency costs and operation and maintenance costs. These estimates are broken down on a sheet-by-sheet basis and also according to jurisdiction. A 25 percent factor is added to the total construction costs which is included to account for fiscal, legal and administrative fees, engineering, surveying, construction inspection, and construction contingencies. The catagorized and total improvement costs for each juriSdiction are summarized in Table 1-1. These cost estimates were further seperated by Reach, the results of which are summarized in Table V-4.