muddy run pumped storage project (ferc no. 2355) - Exelon ...

MUDDY RUN PUMPED STORAGE PROJECT (FERC NO. 2355)
EXHIBIT A-PROJECT DESCRIPTION
1.4. Canal Embankment
The Canal Embankment (NID PA83008), or the Muddy Run Intake Channel Dam, forms the upper part
of the intake channel which leads from the upper reservoir to the intake structure. The lower part of the
channel is excavated in rock. The embankment has a maximum height of about 35 feet, side slopes of
1.5H: 1V and a minimum crest width of 25 feet. The upstream face of the embankment and the rock cut
channel are lined with a nine-inch-thick reinforced concrete slab extending about 1,000 feet upstream on
both sides of the canal from the cylinder gates. The upstream portion of the canal is an unlined soil and
rock cut. River Road Bridge crosses this section of the canal.
1.5. Upper Reservoir Spillway
The spillway for the upper reservoir is located on the west side of the intake canal. It is a concrete ogee
type structure 200 feet long, 20 feet high, has a crest elevation of 521 feet and discharges into a vegetated
natural ravine. A rating curve for this structure is depicted in Figure 1.5-1. The spillway is constructed
within the canal dike and is flanked by concrete retaining walls. Discharges over the spillway would
follow the natural ravine which joins Muddy Run Creek just above its confluence with the Susquehanna
River.
The purpose of the spillway is to protect the embankments from overtopping in the event of inadvertent
over-pumping or in the case of a flood which could not be passed through the generating units. Since
initial filling of the upper reservoir in 1967, the spillway has never been required to pass discharges from
either natural inflows or over-pumping.
1.6. Intake Structure
The Intake Structure which admits water for power generation consists of four cylinder gates with trash
racks (clear spacing of 5.375 inches) (Table 1.6-1). Each intake supplies two units and includes a
cylindrical tower which leads to a 430-foot-deep vertical shaft. The vertical shafts and horizontal power
tunnels are concrete lined with a diameter of 24.5 feet. The concrete lined power tunnels bifurcate
approximately 500 feet upstream of the powerhouse. Beginning approximately 400 feet upstream of the
powerhouse, the tunnels transition to 14-foot-diameter steel penstocks that continue downstream to
connect to one of eight pump turbine units in the powerhouse. There are no inlet valves at the
downstream end of the penstocks.
A-4