C153804 Feasibility Study

• Contract/PO #: C153804
• Contractor Name: Left Hand Ditch Company
• Contract Type: Loan
• Water District: 5
• County: Boulder
• Bill Number: HB 95-1155
• Loan Projects - Doc Type: Feasibility Study

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The Company's property skirts the knob just below the level of the tops of the two dams.
Therefore, to widen the existing spillway would require the purchase of a relatively large tract of
land now owned in common by the Homeowners Association. The Association officers reported
that any sale of commonly owned property would have to be approved by 75 percent of the
mortgage holders or title holders of the 157* lots within the subdivision. This approval, if it could
be obtained at all, would likely be time consuming and could be expensive because of meetings,
paying the Association's expenses for a right-or-way agent and their attorney, preparing exhibits,
etc. It is our opinion that the typical homeowner in the subdivision would not react favorably to
locating the spillway by excavating through the rock knob and therefore would not support the sale
of property to the Company.
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The financial feasibility appears to be no better, and could be much worse, than the Plan C

and Plan D alternatives discussed in subsequent sections of this report. The construction estimate

for Plan C-3b (the cheapest alternative) is approximately $384,000 (Table V-2). In order for the

excavated spillway to be more feasible it must cost less. Preliminary estimates indicate Plan B

would require approximately 60,000 to 70,000 cupic yards of excavation, $100,000 worth of riprap

for the stilling basin and for the berm guiding the flow away from the developed area to the natural

drainage in the northeast, and an allowance of $50,000 for construction of the concrete spillway

crest, revegetation and other miscellaneous con$truction expenses. Plan B also has an associated

unknown condition, the possible existence of hard rock excavation required when cutting through

the knob and down the chute. The cost of excavation of the 60,000 to 70,000 cubic yards of

material could vary dramatically depending on the nature of the material to be removed, especially

if blasting is required. Subtracting the estimated $150,000 for riprap, concrete and miscellaneous

expenses from a maximum of $384,000 (to be no more expensive than Plan C-3b) leaves $234,000

for all earthwork - including excavation, placement of excavated material as fill, and disposal of

excess material or about $3 35 to $3.90 per cubic yard.

We believe that the cheapest at which elCcavation alone could be accomplished would be

assuming that 70 percent of the material to be removed could be easily handled with standard

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