APPENDIX I. TELESCOPING WEIR TECHNICAL SPECIFICATIONS USED FOR PROCUREMENT AND INSTALLATION AT CRANEY ISLAND

ERDC TN-DOER-T3

January 2001

APPENDIX I

TELESCOPING WEIR TECHNICAL SPECIFICATIONS USED FOR PROCUREMENT

AND INSTALLATION AT CRANEY ISLAND

The following specifications are based on structural and mechanical design of the specific size weirs

installed in Craney Island. The unit design was designed to meet a range of water and dredged mate-

rial storage levels common to most placement sites. The design life of a 12-ft telescoping weir was

estimated to be 10-15 years depending on the rate of filling and material consolidation within the

placement site.

Weir Crest Vertical Movement. The weir crest shall be movable over a range of 138 in. 2 in.

between its extreme low and high positions, as determined by mechanical stops. Electrical switches

that shall be set to halt movement approximately 1 in. short of the mechanical stops shall limit the

travel. There shall be sufficient length of vertical actuator to assure that, in the event of failure of the

limit switches, the weir reaches its mechanical stops before the actuators reach the end of their

stroke.

Adjustment Rate. When driven by the electrical motor, the weir height shall be adjustable at a rate

of not less than 2 in. per minute.

Flow Rate. The weir shall be capable of a maximum flow rate of approximately 25 cfs with a head

of 6 in. on the weir crest. It is infinitely adjustable to be capable of being set at the maximum flow

rate consistent with avoiding turbidity in its discharge under any given operating conditions.

Power Requirements. Weir height adjustment is expected to require an input of approximately

0.25 horsepower to lift the dead weight of the weir sections at the adjustment rate of 2 in. per minute.

A motor rated at 1/3 horsepower will be required for reserve power to overcome adverse environ-

mental conditions.

Measurement of Flow Head. The head of the water above the crest of the weir shall be indicated

by a mechanical gauge that can be read in ordinary daylight at a distance of 100 ft, and can also be

read by a person standing on the platform of the weir.

Control Means. The weir adjustment mechanism shall be capable of being actuated in three differ-

ent modes. It can be adjusted either by manipulation of a handwheel or by operation of an electric

motor. The motor can be switched either at the control box located at the weir or from a distance by

means of a hand-held control.

Weight and Envelope Dimensions. The weight of the weir as installed shall be no more than

15,000 lb. The envelope of the weir as installed shall be 8 ft wide by 8 ft long by approximately 28 ft

tall measured from the bottom of the foundation to the top of the weatherproof covers that protect the

jackscrews.

Weir Crest Section. The weir crest section shall be a thin-walled cylinder of corrosion-resistant

steel, nominally 85.5 in. in outside diameter, 48 in. long, and 0.25 in. thick. A set of bearing blocks

shall be attached around the lower perimeter of the crest section to engage the upper rim of the