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Alternatives


Preliminary alternatives have been developed for the North Delta Flood Control and Ecosystem Restoration Project. Solution components being considered for flood control include setback levees, detention basins, dredging and levee degradation for floodplain expansion. Proposed Project actions and alternatives are subdivided into two basic groups for analysis in the EIR- see discussion below regarding Alternative Groups. A preferred alternative will be chosen through the EIR process and will be identified in the Final EIR.

Group 1 Alternatives

  • Alternative 1-A: Fluvial Process Optimization $44M* (PDF: 4.7 MB)
    This alternative facilitates controlled flow-through of McCormack-Williamson Tract during high stage combined with a scientific pilot action of breaching a levee to optimize fluvial processes. The southernmost portion of the tract would be open to tidal action.
  • Alternative 1-B: Seasonal Floodplain Optimization $47M* (PDF: 4.7 MB)
    This alternative facilitates controlled flow-through of McCormack-Williamson Tract during high stage combined with actions to maximize floodplain habitat to benefit fish species that spawn or rear on the floodplain. This would be accomplished by allowing controlled flooding (with some tidal action to maintain water quality) during the wet season.
  • Alternative 1-C: Seasonal Floodplain Enhancement and Subsidence Reversal $51M* (PDF: 5.1 MB)
    This alternative facilitates controlled flow-through of McCormack-Williamson Tract during high stage combined with scientific pilot actions to create floodplain habitat (similar but less than Alternative 1-B), combined with a subsidence reversal demonstration project in the lowest area of the tract. This would be accomplished by allowing controlled flooding (with some tidal action to maintain water quality) during the wet season, as well as sediment import.

Group 2 Alternatives

  • Alternative 2-A: North Staten Detention $209M* (PDF: 5.3 MB)
    This alternative provides additional capacity in the local system through construction of an off-channel detention basin on the northern portion of Staten Island. High stage in the river would enter the detention basin upon cresting a weir in the levee. Other components are combined to protect infrastructure. Similar to all the detention alternatives, this alternative is designed to capture flows no more frequently than the 10-year event while having no measurable effect on the 100-year floodplain. The interior of the basin would continue to be farmed, consistent with current practices.
  • Alternative 2-B: West Staten Detention $327M* (PDF: 5.4 MB)
    This alternative provides additional capacity in the local system through construction of an off-channel detention basin in the western portion of Staten Island, along the North Fork Mokelumne River. High stage in the river would enter the detention basin upon cresting a weir in the levee. Habitat restoration is integrated with the construction of a setback levee. Other components are combined to protect infrastructure. Similar to all the detention alternatives, this alternative is designed to capture flows no more frequently than the 10-year event while having no measurable effect on the 100-year floodplain. The interior of the basin would continue to be farmed, consistent with current practices.
  • Alternative 2-C: East Staten Detention $248M* (PDF: 5.2 MB)
    This alternative provides additional capacity in the local system through construction of an off-channel detention basin on the eastern portion of Staten Island, along the South Fork Mokelumne River. High stage in the river would enter the detention basin upon cresting a weir in the levee. Habitat restoration is integrated with the construction of a setback levee. Other components are combined to protect infrastructure. Similar to all the detention alternatives, this alternative is designed to capture flows no more frequently than the 10-year event while having no measurable effect on the 100-year floodplain. The interior of the basin would continue to be farmed, consistent with current practices.
  • Alternative 2-D: Dredging and Levee Modifications $103M* (PDF: 5.6 MB)
    This alternative provides additional channel capacity by dredging the river bottom and modifying levees.

The flood performance of the various alternatives is presented in the Tidal and Flood Hydraulic Modeling Technical Appendix (PDF: 1.4 MB)

Alternative Groups

Proposed project actions and alternatives are subdivided into two basic groups for analysis in the Project EIR, under the following considerations.

A grouped approach has been chosen to allow flexibility in implementation depending on determination of incremental Project need, available funding, and Project partnerships. It should be noted that the grouped analysis simply facilitates a phased implementation and would not preclude the implementation of the Project as a single phase.

The groups are being developed to be independent, such that the proposed component actions are targeted to meet group-specific objectives and that the groups are not-inter-reliant for mitigating impacts (i.e. Group II is not required for mitigation of Group I).

Both groups are analyzed at the level of detail available; however, implementation of some elements may require additional CEQA analysis, depending on the specific details discovered through Project development. Such additional analysis may be documented through a tiered negative declaration or technical addendum and may not require a supplemental or subsequent EIR.

 

*“All costs identified above are approximate and based upon 2006 estimate prepared by J & S”