APPLICANT PACKET - Virginia Department of Conservation and ...
APPLICANT PACKET - Virginia Department of Conservation and ...
APPLICANT PACKET - Virginia Department of Conservation and ...
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6. Anti-Vortex Device <strong>and</strong> Trash Rack: An anti-vortex device <strong>and</strong> trash rack shall be attached to the top<br />
<strong>of</strong> the principal spillway to improve the flow characteristics <strong>of</strong> water into spillway <strong>and</strong> prevent floating<br />
debris from blocking the principal spillway.<br />
7. Dewatering: Dewatering <strong>of</strong> the dry storage should be done in a manner which removes the "cleaner"<br />
water without removing the potentially sediment-laden water found in the wet storage area or any<br />
appreciable quantities <strong>of</strong> floating debris.<br />
An economical <strong>and</strong> efficient device for performing the drawdown is a section <strong>of</strong> perforated vertical<br />
tubing that is connected to the principal spillway at two locations. See Plate 3.14-15 that depicts the<br />
orientation <strong>of</strong> such a device. By virtue <strong>of</strong> the potential for the dewatering device or orifice becoming<br />
clogged, no credit is given for drawdown by the device in the calculation <strong>of</strong> the principal or emergency<br />
spillway locations.<br />
8. Anti-Seep Collars: Anti-seep collars shall be used on the barrel <strong>of</strong> the principal spillway within the<br />
normal saturation zone <strong>of</strong> the embankment to increase the seepage length by at least 10%, if either <strong>of</strong><br />
the following two conditions is met:<br />
a. The settled height <strong>of</strong> the embankment exceeds 10 feet.<br />
b. The embankment has a low silt-clay content (Unified Soil Classes SM or GM) <strong>and</strong> the barrel is<br />
greater than 10 inches in diameter.<br />
Applicant Packet 69<br />
June 2001