PROJ00476

• Contract/PO #: C153594
• Contractor Name: Handy Ditch Company
• Contract Type: Loan
• Water District: 4
• County: Larimer
• Bill Number: HB 91-1006
• Loan Projects - Doc Type: Feasibility Study

.
I
I
I
I
I
I

J

I
-
,
I
I
I
I
I
I
f
I
I

CHAPTER V
PlAN OF DEVELOPMENT

A. Physical Plan
A sink hole was discovered near the toe of Welch Reservoir on June 25,
1990. The sink hole was located at the No. 1 outlet, directly above the
outlet pipe where the outlet pipe is crossed by an irrigation lateral which
runs along the downstream toe of the dam. The sink hole was approximately 6
to 8 feet deep and 8 feet in diameter. On June 27, 1990 a video inspection of
the outlet pipe was conducted. The video revealed a clay tile pipe with water
leaking through several joints and a longitudinal crack along the top of the
pipe approximately 50 feet in length. The camera was not able to travel
further than 100 feet into the outlet pipe from the south end as the pipe
appears to decrease in diameter from 18 inches to 15 inches at this 100-foot
point. The location of the decrease in pipe diameter corresponds with the
sink hole location.
A temporary repair design and monitoring program were developed by Rocky
Mountain Consultants, Inc. and approved by the State engineer's Office on June
18, 1990. Construction began on the same day. The sink hole area was
excavated and a filter pack was constructed. The irrigation lateral was also
repaired. The reservoir outlet was opened slowly on June 29, 1990 to allow
water flow to meet the downstream irrigation demands. The temporary repair
was designed to allow irrigation for this season. During outlet operation,
the Handy Ditch Company was required to follow a stringent monitoring program
of twice daily inspections of the dam and outlet works.
The State Engineer's Office approval (see Appendix B) of the plan was
contingent on:
1. Submission of a report of the work done, materials used and

22