2011-03-14_REVISION - M1977493 ‎(65)‎

• Permit No: M1977493
• IBM Index Class Name: REVISION
• Doc Date: 3/14/2011
• Doc Name: Exhibit List, Ex. 70
• From: Climax
• To: MLRB
• Type & Sequence: AM6
• Media Type: D
• Archive: No

CM0001768
Page 14
For the static slope stability evaluation, under steady state seepage and rapid drawdown
conditions, the Rules for a Class IV small dam identify the minimum FOS to be 1.5 and 1.2,
respectively. The Rules identify the psuedostatic evaluation to indicate a minimum FOS of 1.0.
Discussion of the bedrock acceleration and other key model geotechnical input parameters used
to perform the static and psuedostatic slope stability evaluations are included in the Appendix D
`Static and Pseudo-Static Slope Stability Calculation Brief. The calculation brief also includes a
FOS summary table of each slope stability analysis performed.
Four slope stability evaluations were modeled on two cross sections. The first cross section
represented the Dam on a level grade, and the second included the borrow area cuts on each side
of the Dam. For each slope and each side of the Dam, static. and pseudo-static slope stability
evaluations were performed to evaluate steady state flow and rapid drawdown conditions. All
slope stability analyses performed indicate that the Dam's slopes would provide an acceptable
FOS to meet Class IV small dam stability under the most critical rapid drawdown with
earthquake loading conditions.
4.11 Pipe Conveyance System
As shown on Figure 6, the conveyance pipe system consists of a 24 inch diameter high density
polyethylene (HDPE) pipe, epoxy-coated cast iron butterfly valves, anti-seep collar, concrete
headwalls and fiberglass/steel walkways. The conveyance pipe was' added to allow the
controlled transfer of water through the Dam between Robinson Lake and the Seepwater Pond.
The design parameters and details evaluations for specifying the conveyance pipe, concrete
headwall and associated appurtenances are contained in `Conveyance Pipe System Design';
Conveyance Pipe Headwall Design'; and `Walkway Support and Connection Design' calculation
briefs provided in Appendix E'. Table 4 identifies the conveyance pipe discharge apron material
quantity required as calculated in the `Summary of Construction Materials Calculation Brief
provided in Appendix E.
4.12 Spillway Design
1J
As shown on Figure 6, the spillway consists of a 50 feet wide by three feet deep rectangular
concrete channel constructed on the Dam crest and 50 feet wide by 3 feet deep riprap-lined
channel constructed down each face of the Dam. The spillway was included to allow an
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