C153514 Feasibility Study

• Contract/PO #: C153514
• Contractor Name: Farmers Water Development Company
• Contract Type: Loan
• Water District: 60
• County: San Miguel
• Bill Number: SB 87-15
• Loan Projects - Doc Type: Feasibility Study

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Other foundation restoration alternatives considered included
blanketing of the upstream foundation and a combined foundation
grouting and blanketing program. Blanketing techniques have been
used previously at Gurley Reservoir Dam with some success over the
short-term but with little to no success over the long-term. We
believe that continued attempts to apply this remedial technique
are likely to produce unsatisfactory results and may be difficult
and expensive to apply over 1 arge areas due to the presence of
unknown thicknesses of riprap and dozed riprap/soil debris on the
upstream embankment face and foundati on. For these same reasons,
combined foundation grouting and blanketing program would rely
primarily on the foundation grouting work for continued long.,.term
effectiveness. Therefore, the money which would be spent on
blanketing would probably be better spent on upgrading the
foundation grouting program instead.

Based on the above arguments, we have desi gned a foundation
restoration program which relies extensively on foundation grouting
in conjunction with the salutory side effects of the outlet works
rehabilitation program to reduce the potential for continued
sinkhole development.

The proposed foundation grouting program will consist of the
following components:

1. Construction of a grouting platform and access road along
the upstream face of the dam in the area to be grouted;

2. Drilling, water testing and grouting a three-line grout
curtain in the dam foundation from the grouting platform;
and

3. Confirmation coring and water testing in the dam
foundation at selected locations to check the
effectiveness of the foundation grouting program.

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