Wenger 72944 Especificações descarregar pdf (Página 204)

Section 5 Formulation of Alternative Plans

EAA Storage Reservoirs Revised Draft PIR and EIS February 2006

5-50

The risks due to this project are:

1. Risk to downstream settlement due to dam breach.

2. Higher than expected downstream damages during release of major floods

due to infrastructure encroachment of flood plains.

To minimize these risks, a sub-regional model was used to determine seepage

rates and probability of spillover and the reservoirs operations manual will

include management measures such as:

1. Developing a reservoir regulation schedule.

2. Creating flood storage prior to predicted storm.

3. Design of outlet structures to handle release water after a major storm in

preparation for a subsequent storm.

5.4.4.2 Engineering

The risk and uncertainty associated with the construction and operation of the

features of the EAA Storage Reservoirs project and earthen embankment

construction should be minimal. All features have been designed and

constructed through established and applied technology. Additionally, both the

USACE and the SFWMD have extensive and reputable credibility in the design,

construction, and operation and maintenance of the proposed features from

previous water resources planning efforts.

However, there are uncertainties associated with the construction of an RCC

embankment. These include, 1) the fact that the USACE and SFWMD both

have more experience constructing earthen levees in South Florida than RCC

structures of this scale; 2) the current shortage of Portland cement in South

Florida which could significantly increase RCC cost estimates (the USACE’s

Cost Engineering Branch is currently investigating this cost issues to determine

if changes to future cost estimates are appropriate); and, 3) the fact that limited

geotechnical data is available for the entire area being considered for the

reservoirs, which could affect the cost estimates for foundation treatment and

cut-off wall required for RCC construction (both the USACE and SFWMD are

currently collecting additional geotechnical data within the Study Area that will

be available for use in the final PIR).

5.4.4.3 Evaluation of System-wide Ecological Effects of Hydrologic Performance

Measures

Hydrologic performance measures are useful for determining and comparing the

effects of alternative plans. However, to determine a plan’s outputs for purposes

of depicting NER benefits, the assumption is made that the hydrologic

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Wenger 72944 Especificações Página 204