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Section 6 The Selected Alternative Plan

EAA Storage Reservoirs Revised Draft PIR and EIS February 2006

6-19

6.4.1.1.2 RipRap Slope Protection

The interior face of the earthen reservoir embankment will be protected with a

24-inch thick layer of riprap revetment for erosion protection against wave

action and water level fluctuation. The material for this riprap will come from

blasting the caprock layer immediately below the superficial peat-silt layer

overlaying the EAA area. The riprap revetment will cover the top sloped face of

the embankment and the top of the wave breaking berm. The sloped face of the

wave breaking berm will be protected with a 12-inch thick layer of soil-cement.

Geotextile filter fabric will be placed under the riprap revetment layer.

6.4.1.1.3 Soil-Cement Slope Protection

The slope face of the wave breaking berm for the earth embankments will be

protected by a 12-inch layer of cement treated soil. The soil will be select fill

from the layer under the caprock. An approximate 12% Portland Cement will be

added into the soil, together with a designed amount of water, mixed in a pug-

mill, placed and compacted.

6.4.1.2 General Construction Considerations

6.4.1.2.1 General Embankment Foundation Preparation

The reservoir embankment foundation footprint should be cleared of the peat-silt

layer, to the caprock. The embankment fill material will be placed and

compacted directly over the caprock. About one foot of the caprock layer will be

scrapped off to secure an even and stable foundation for the embankment.

6.4.1.2.2 Peat-Silt Layer

During excavation of the seepage collection canal, clearing of the embankment

footprint and excavation of the borrow pits, a substantial quantity of peat-silt

material will be generated. Although some of this material will be used in the

creation of tree islands in the exterior seepage buffer, there will be a surplus of

this type of material. The surplus material may be placed back into the borrow

pits.

6.4.1.3 Seepage Canal and Seepage Buffer Area

6.4.1.3.1 Seepage Canal

Excavation of the seepage canal and borrow pits will require clearing of the peat-

silt layer, followed by blasting of the caprock layer prior to the excavation of silty

sand/limestone layer. The seepage canal is 50 feet wide at the bottom and 18

feet deep. The side slopes are 1V:2H. A 30-foot wide environmental littoral shelf

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Wenger 72944 Spezifikationen Seite 247