PROJ00158

• Contract/PO #: C150098
• Contractor Name: Lake Henry Reservoir Company
• Contract Type: Loan
• Water District: 17
• County: Crowley
• Bill Number: HB 02-1152
• Loan Projects - Doc Type: Feasibility Study

Allen Ringle

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Graber, Mike ([e-mail])
Thursday, August 02, 2001 1 :41 PM
Allen Ringle
The Long Awaited Lake Henry Hydrology and spillway study

Allen-

I told you I would have a hydrology study, approximate spillway size and
very rough cost estimate for you by the first week in August and true to my
word. Here it is, This was a pretty quick study, but it gets you in the ball
park, not home plate mind you but more like the nose bleed section, For a
50% Probable Maximum Flood, which is what Lake Henry is required to safely
rout with one foot of residual reservoir freeboard, you would need a 4 feet
deep by 400 foot long concrete spillway, The spillway would be flowing 3
feet deep with this inflow flood having a spillway discharge of 2150 CFS,
The actual construction cost of the spillway would be in the neighborhood of
$250,000, add about $75,000 for engineering and contract administration and
arrive at $325,000. It would be prudent to consider building the spillway to
handle 75% of the probable Maximum Flood as is required for a Class 1, in
the event the dam changes hazard class due to downstream development, If
that were to happen, you would have to increase the spillway capacity to
handle the larger flood or suffer a storage restriction. This would add an
additional 25% cost to the project, which puts you at roughly $400,000. I
would go for much larger loan than you think you might need, because you
only have to borrow what you need, but if you need more than your borrowing
limit, it means starting over with a lengthy process.

Please remember that all of these numbers are very approximate and should
not be used for more than planning purposes, Good luck with the project and
I hope this information is helpful,

Mike Graber

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