PROJ00382

• Contract/PO #: C153685
• Contractor Name: Monument, Town of
• Contract Type: Loan
• Water District: 10
• County: El Paso
• Bill Number: SB 94-029
• Loan Projects - Doc Type: Feasibility Study

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Chapter III - Background Information

outfall and gate chamber. Site photographs tak0n during the inspection are presented in
Appendix B.

The operational status of the dam and reservoir during the inspection was as follows. The

reservoir was approximately three feet below the spillway crest, which is the restricted level

imposed by the SEO, and as indicated by a metal rod in the approach channel of the spillway.

The right outlet works gate was closed, and the left outlet works gate was partially open. The

outlet discharge, however, is not known. The weather during the inspection was pleasant and

sunny, with temperatures in the 40's. Portion of the reservoir surface was frozen, and most of the

exposed upstream slope was still with snow.

The annual dam inspection was performed by the SEO on July 12, 1999. During the

month of June sever storms occurred, which reqllired the use of the spillway. The water depth

over the weir was approximately 2 feet during the storm events. During the annual inspection, it

was observed that additional erosion had occurred in the spillway chute due to the storm event.

The foundation of the gab ion structure showed additional signs of erosion, which caused the

gabion structure to lean into the spillway chute even more than observed during the inspection in

February.

Additional erosion occurred along the ea~;t-training wall during the storm event. A 2- to

3-foot-wide erosion gully along the toe of the left training wall was formed during the storm

event.

The following is a description of the obs~rvations that were made during the site

inspection. Comparisons are made with previow; reported observations in the SEO report where

appropriate. Photographs were taken and referenced in this report to illustrate some of the

observations.

The upstream slope of the reservoir is protected with riprap stones that are typically 6 to

12 inches in size. These stone sizes appear to be too small. Some weathering was observed in

the stones, but the stones are considered to be of acceptable quality. The slope has some locally

steep scarps about one foot high near the former nigh water line, with embankment fill exposed

on the scarp faces. Beaching had occurred below the high water line, with very flat slopes along

Monument Lake Dam Feasibility Study

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BDYLE