OKLAHOMA CITY – A project to repair the damaged spillway at Lake Ellsworth received the blessing Tuesday of the Oklahoma Water Resources Board.
The Ellsworth spillway is a 300-foot-wide concrete structure consisting of an ogee weir, apron, and a stilling basin (see accompanying diagram).
According to Yohanes Sugeng, engineering manager with the OWRB’s Planning & Management Division, several sections of the apron have been adversely affected “due to supporting expansive soil uplifting that damaged the concrete.” The uplift ranged from 0.2 feet to 0.8 feet across the spillway, and most of the damage occurred at joints in the concrete, Sugeng said.
Officials with the OWRB and the City of Lawton said rehabilitation measures will include adding more robust rock anchors, installing additional drains under the apron and grouting under the existing concrete, casting a new reinforced concrete slab over the existing apron, and replacing the stilling basin at the foot of the spillway.
Rusty Whisenhunt, Lawton’s public utilities director, said the city has applied to the Federal Emergency Management Agency for a grant that would finance 75% of the $21 million estimated cost of the spillway rehabilitation project.
The Ellsworth dam was constructed in 1961-62 to impound East Cache Creek, according to the Water Resources Board. The dam is 3,900 feet long and 96 feet high, OWRB records reflect.
The lake is one of Lawton’s primary sources of drinking water. Its normal capacity is approximately 81,000 acre-feet, which is more than 26 billion gallons of water. The reservoir encompasses 5,100 surface acres in northern Comanche and southern Caddo counties, has 53.5 miles of shoreline, and has a maximum depth of 54 feet.