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Section 6 The Selected Alternative Plan

EAA Storage Reservoirs Revised Draft PIR and EIS February 2006

6-12

6.1.10 Other Features

6.1.10.1 Wetlands Buffer

A 200-foot buffer area runs along the east, north, and western boundaries of the

reservoir. This seepage buffer will extend 200 feet from the base of the

embankment. It will provide both seepage control and wildlife habitat within

the project footprint, encompassing a total of 560 acres. The design of the buffer

is to mimic an upland-wetland mosaic and allow for maintenance of the reservoir

embankment (Table 6-4). The first 50 feet of the buffer will be an upland

maintenance corridor. From 50 to 100 feet, the buffer area would be regarded

post-construction to the existing grade and allowed to re-vegetate naturally as a

wetland. From 100 to 200 feet, the buffer area would contain a deeper (-2 feet

elevation from existing) excavated wetland interspersed with tree islands sloped

to 4 feet above existing grade. Tree islands will be approximately 50 feet wide,

and occupy approximately 75% of the total length of linear feet of buffer area.

Therefore, approximately 95 acres of tree island habitat will be provided within

the buffer. Wetlands created and restored in the buffer footprint will be

approximately 404 acres of wetland habitat. The wetland portions would be

hydrated by rainfall, seepage from the reservoir, and perhaps groundwater

“backed up” from the cut-off walls. The elevated tree islands will be planted

with native tree vegetation of appropriate species. See Figure 6-4 for a

conceptual cross section.

FIGURE 6-4: CONCEPTUAL CROSS-SECTION OF THE EAA PROJECT

FOOTPRINT INCLUDING THE SEEPAGE/HABITAT BUFFER AND LITTORAL

SHELVES

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