FLOOD11759

• County: Mesa
• Stream Name: Bosley Wash
• Basin: Colorado Mainstem
• Title: Bosley Wash Drainage Master Plan - Phase 2: Alternative Drainage Facility Evaluation - Draft
• Date: 11/1/2002
• Prepared For: Bosley Wash Watershed, CWCB
• Prepared By: HDR Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Bosley Wash Drainage Master Plan

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Phase 2: Alternative Drainage Facility Evaluation

construction of an additional 48-inch diameter culvert or the construction of an entirely
new 60-inch diameter culvert. Cost of these improvements is estimated to be $100,000.

3.3.4 UPRR/Highway 6 Crossing

The culvert under the Hwy 6/UPRR crossing creates a significant upstream flood hazard.
This structure, when enlarged by the construction of a 36-inch pipe adjacent to the
existing structure will result in a major reduction in upstream flooding. This crossing is
also unique to the Bosley system in that the downstream channel has the capacity to
handle the flows that are likely to be conveyed by the improved culverts. The cost of
these improvements is estimated to be $100,000.

3.3.5 Upstream along UPRR

Culverts along the UPRR embankment, between 34 Yz Road and 34 1,4 Road, restrict the
flow of water. Enlargements or replacements of these culverts will reduce the out of
channel flooding that creates a nuisance along the track embankment. Cost of these
improvements, which will consist of installation of 48-inch culverts, will be $130,000.

3.4 Property Acquisition

Acquisition of flood prone properties is a very effective way of reducing flood damage.
Unfortunately, the cost of such an alternative is very high relative to the actual value of
the damages experienced during floods. In fact, in many cases, the cost of property
acquisition vastly exceeds the value of actual damage, even during the 100-year flood.
Nevertheless, the affected properties for a variety of flood scenarios have been identified
and the cost of property acquisition estimated.

3.4.1 Structures impacted by flooding

The basic level of property acquisition was the identification of parcels for which
structures were impacted during flood events. This acquisition approach resulted in the
identification of 88 acres of property with impacted structures and a cost of $1.4 million
dollars. Figure 11 depicts the parcels which have structures impacted by flooding.

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