FLOOD06837

• County: Alamosa
• Community: Alamosa
• Stream Name: Rio Grande
• Basin: Rio Grande
• Title: Master Drainage Plan Alamosa
• Date: 3/1/1982
• Prepared For: Alamosa
• Prepared By: McCarty-Hurst
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Each intersection will need larger inlets so as to allow
for the greater capacities.

One potential problem is the depth of excavation with the
size of the proposed pipes. Coupled withca high ground
water table and adobe clay, this problem could create con-
struction problems that would increase construction costs
over standard cost averages. Staged construction, due to
funding limitations, is possible with sections being built
from the Rio Grande River upstream. Staged construction
will relieve overloading problems, but will not eliminate
the ponding around Alamosa Inn until the entire reach is
constructed. Advantages of this alternative are smaller
costs for right-of-way and essentially eliminating all
major flooding problems.

Alternative'2. This alternative consists of a combination
of pipe and detention ponds, with laterals as in Alterna-
tive 1. In stage one, starting at the Alamosa Inn, a pipe
is proposed to cross the main highway to the borrow pit area
between the highway and the railroad embankment. This bor-
row pit area would serve as a retention/detention pond, de-
pending upon the various stages constructed and the design
frequency. This plan transfers the flooding from the Alamosa
Inn to the pit area. It would then be pumped away or left to
evaporate and solves the immediate flooding problem.

The pipe crossing can be designed for the 100-year future
flow or some lesser capacity to fit with the other portions
of Alternative 2. A pipe designed for the future 100-year
storm can function with the assumption that this pond area
will, in the future, have sufficient capacity to control
the 100-year storm. As an alternative, a pipe designed

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