FLOOD07758

• County: Denver
• County: Jefferson
• Community: Lakewood, Denver, Jefferson County
• Stream Name: Lakewood Gulch
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 12/1/1979
• Prepared For: Denver / Lakewood / Jefferson County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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present the construction and land costs and column 9 in the

same Table presents operation and maintenance costs. In order

to present a comparison of costs and the previously described

benefits, the land and construction costs are converted to

average annual costs for a 50-year life at a 6-5/8% interest

rate. These costs are then added to the operation and mainten-

ance costs to determine the Total Average Annual Costs. It

should be noted that land acquisition costs are a significant

portion of the total construction costs. These costs are more

difficult to estimate and therefore subject to considerable

variation. These land acquisition costs are for obtaining

easements to provide access for maintenance.

2l

A detailed cost estimate for each sheet of the Master Plan

drawings is shown adjacent to the plan in the following

Section. Annual unit costs for operation and maintenance are

exhibited in Table VI-2. The unit prices used for estimating

the construction costs are shown in Table VI-3.

Comparison of Costs and Benefits

Table VI-l presents, for each reach, a comparison of the costs

and benefits in the basin. It should be noted that the benefits

and costs may vary radically from reach to reach, indicating

that construction of facilities is more cost-effective in

certain reaches. This can be seen in two parameters, the net

annual benefit, which is the difference between the average

annual benefits and the average annual costs, and the benefit-

cost ratio, which is the ratio of the average annual benefits

to the average annual costs. If the net annual benefits are

negative, or if the benefit-cost ratio is less than unity, the

cost of implementation of the Master Plan exceeds the value of

the benefits to be derived.

Table VI-4 exhibits a summary of the total costs of the two
improvement phases considered.

As pointed out in the Section "Determination of Benefits,"

benefits accruing from a maintenance access along the drainage

course, and from the prevention of flooding of major arterials,

were not quantified. This must be remembered when the benefit

cost ratios for different reaches are analyzed and found to be

less than unity.

Costs shown in Table VI-l are for only the first of two phases
of construction considered herein. A detailed explanation of
the two phases is presented in Section VII.