Specifications

Section 5 Formulation of Alternative Plans
EAA Storage Reservoirs Revised Draft PIR and EIS February 2006
5-22
5.3.7 Emergency Overflow Spillway
All alternatives were designed to contain the routed Probable Maximum Flood
(PMF) without the use of an emergency overflow spillway. Since this is an
overground reservoir the PMF is same as capture of the Probable Maximum
Precipitation (PMP) event on the reservoir. Use of an emergency overflow
spillway will be investigated and included in the design phase.
5.3.8 Conveyance Canals Design
Back water computations using HEC RAS were performed to determine existing
conveyance capacity for the Miami and North New River Canals. Based on these
runs, the existing capacities for the Miami and North New River Canals were
3,000 and 2,000 cfs, respectively. Canal conveyance improvements up to 150%
were estimated for both the North New River and Miami Canals. Additional
conveyance improvements may be necessary to reduce irrigation demands upon
Lake Okeechobee. These improvements will be determined through a water
budget routings analysis to be performed by the sub-regional Mike-SHE model
in the final PIR.
5.3.9 Flood Damage Reduction
The EAA storage reservoirs design will be required to meet the Savings Clause
requirements of maintaining existing Level of Service (LOS) for flood protection
(see Annex G for results of this evaluation). As previously discussed, any flood
protection improvements or benefits that result from the implementation of this
Project are considered incidental, and not a specific project goal. The existing
flood protection, better described as flood damage reduction, contains a removal
rate of ¾-inch per day for the EAA basin. However, removing runoff (untreated
agricultural runoff) at this rate is not desirable due to water quality concerns in
the WCAs and Lake Okeechobee. By providing 360,000 acre feet of storage
capacity that is not currently available, the EAA reservoirs will significantly
reduce (though not eliminate) pumping of runoff into Lake Okeechobee flows to
the WCAs. The sub-regional MODFLOW model will be the design tool utilized
to ensure that the EAA Project meets the Savings Clause requirements for LOS
flood projection.
5.3.10 Land Requirements
5.3.10.1 Alternative 2
Approximately 62,000 acres would be required for the Alternative 2. This
alternative would use the entire footprint of Compartment A, comprised of
approximately 31,500 acres owned by SFWMD. All remaining lands required for