PROJ00434

• Contract/PO #: C153337
• Contractor Name: Farmers Extension Ditch & Highland Lake Lateral Company
• Contract Type: Loan
• Water District: 1
• County: Weld
• Bill Number: FSA
• Loan Projects - Doc Type: Feasibility Study

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time on, but it does happen to every channel which has moving water. This is
illustrated on Exhibit No.5.

Velocities change constantly in an irrigation ditch due to the checking process

used to deliver water to the stockholders. When the water has been checked, up-

stream velocities are very slow causing the settlement of solids. But when the

structure is unchecked and the water velocities increase, sediment is picked up

again, and in the process forces additional sediment from the embankments and

carries it downstream. This causes a constant erosion of the embankments.

Turbulence causes scouring within the channel lining. When large stones, rocks

or other objects settle to the bottom of the ditch, currents of water swirl around

them causing turbulence in the downward direction. This movement exerts a pressure

against the embankment much the same way as the water pressure from a hose exerts

pressure on a garden bed. And in the same way as a garden bed, stability within

the soil is not enough to resist movement, therefore, scouring occurs as shown

on Exhibit No.5.

Weather, tailwaters, and stormwaters also are cuases of ~rosion and scouring.

All these factors combined will constantly work away at the ditch causing ben-

tonite or chemical sealant to wear away. When untreated soil is reached, this

process becomes more rapid and complete reconstruction is needed.

The only way an earthen ditch would be workable is if a yearly maintenance pro-

gram was established to recompact and add bentonite or a sealant to the ditch.

This, of course, violates our second rule, to minimize operation and maintenance

costs. There are appoximately eleven (11) miles of ditch. Assuming our ditch

.was of the cross-section shown in Exhibit No.4, this would mean there would be

approximately 755,000 square feet a year which would have to be maintained. The

estimated annual cost for this maintenance is $68,000 and is broken down as follows:

1. Bentonite (.02/ft2) or chemical sealant1 + additional dirt (.02/ft2)l
2. Equipment $75/hour (compactors)
3. Labor $30/hour - 2 men at $15/hour each
4. Inspection $25/hour - 1 man at $25/hour

lWestern Equipment Company - Denver, Colorado

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