NCG020925_James Cahoon Mine - Cahoon_Water Height Control-2_20180220

Water Height Control: Construction Details
Half-pipe Water Level Control with Flash Board Risers
NRCS Code 587
James Cahoon Mine
US 64 East, Columbia, NC
Tyrrell County

DESCRIPTION
A structure in a water management system that conveys water, controls the direction or rate of flow, maintains a desired
water surface elevation or measures water. Water height control structure is standard structure used by agricultural and
horticultural farms in North Carolina to raise or lower water height in ditches and ponds per need (NRCS). Water height
control structure to be installed in the northeast corner of the sedimentation pond berm at the James Cahoon Mine.
Overflow to be directed down stabilized ditch to nearby blue-line stream, eventual outflow to Scuppernong River and
Albemarle Sound.

PURPOSE
To convey water from one elevation to a lower elevation within, to, or from a water conveyance system, such as a ditch,
channel, canal, or pipeline designed to operate under open channel conditions. Typical structures: drops, chutes,
turnouts, surface water inlets, head gates, pump boxes, and stilling basins (NRCS). This water management system will
be used to maintain a maximum water surface elevation in the sedimentation pond at the James Cahoon Mine, US 64
East, Columbia, NC. Sedimentation pond is a part of the dewatering management system of the James Cahoon Mine,
used to remove settleable matter and turbidity from mine dewatering wastewater.
CONSTRUCTION
Structure consists of 26’ x 3’ horizontal galvanized steel culvert running under the sedimentation pond berm. A vertical 6’
half pipe 52” x 30” is attached on the north end of the culvert with stacked flash boards allowing adjustable height of the
water level in the sedimentation pond. Water flows over the flash boards and into the discharge pipe and down the rip-rap
stabilized ditch.
Overflow ditch is lined with riprap for 20 feet down its length. Existing slopes adjacent to the culvert are heavily grassed
with natural grass and weeds with no erosion present.
MAINTENANCE
Structures will be checked and necessary maintenance, including removal of debris, shall be performed after major
storms and at least semi-annually.

Ken Elliott, consulting
January 28, 2018