PROJ00206

• Contract/PO #: C153574
• Contractor Name: Longmont, City of
• Contract Type: Loan
• Water District: 5
• County: Boulder
• Bill Number: SB 88-30
• Loan Projects - Doc Type: Feasibility Study

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VI. PLAN OF DEVELOPMENT

A. Introduction

The purpose of this project is to rehabilitate McCall Lake Dam. In addition

to rehabilitating the dam, some additional appurtenances associated with the dam

are proposed that will give the City of Longmont numerous options for use of

McCall Lake water.

Over the years, the embankment and spillway have deteriorated to the point

of needing complete rehabilitation. This need was highlighted recently by the
State Engineers Office (SED) during their last dam inspection. Copies of the
1985, 1986 and 1987 dam inspection reports are in Appendix D.

McCall Lake dam has a Class II Moderate Hazard Classification. Major

problems identifed by the dam inspector at the SED included:
- The upstream embankment slope is too steep,
- Riprap protection of the embankment is required,
- Brush and trees from the downstream slope and rotten stumps
from the upstream slope need to be removed,
Repair or replacement of the existing pipe outlet is required.
Improvements or new structures considered by the City of Longmont in addi-
tion to SED recommendations include:

- Construct a more permanent concrete spillway and provide riprap
protection of the concrete spillway,

- Construct a diversion structure from the Longmont Supply Ditch to the
Oligarchy Ditch; and

Extend the toe drain pipe near the dam outlet to Independent Reservoir.
B. Proposed Improvements
The City of Longmont proposes to make the following improvements to McCall
Lake: (1) flatten and protect the existing embankment, (2) construct a new
spillway, (3) construct new outlet works, (4) extend the existing toe

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