Birmingham Water Works carries out repairs to prevent Lake Purdy dam from spilling: CEG

A dam that supports one of the Birmingham, Alabama, metropolitan area's most important sources of drinking water is undergoing an $85 million renovation after years of leaking millions of gallons of water every day.

The Birmingham Water Works Board (BWW) approved construction contracts in mid-September for work on the more than 100-year-old Lake Purdy Dam in Shelby County.

The board voted 7-1 to award a $78.7 million contract to Thalle Construction Co., based in Hillsborough, North Carolina, and to award $6.8 million in management fees to Arcadis, an engineering firm with an office in Birmingham. Schnabel Engineering in Glen Allen, Virginia; and Birmingham's AG Gaston Construction.

“Our ultimate goal is to always ensure we provide our customers with safe, affordable and high-quality water,” Tereshia Huffman, chairwoman of the BWW board, told AL.com. “This dam is old and it was time for us to make a conscious effort to make sure we got the funding.”

She added that the project will improve the dam's structural stability and address water leaks at its foundation.

The Lake Purdy Dam was built in 1909 and the damming of the Little Cahaba River created the reservoir in 1923. Six years later, the dam was raised by 20 feet to bring the lake to its current size of 990 acres just above the confluence of the Little Cahaba and Cahaba Rivers.

Access to the structure is via Lake Purdy Dam Road with gated entrances at Sicard Hollow Road and Cahaba Valley Road. The water released from the reservoir's overflow enters the Cahaba, where it is received by the BWW's Cahaba pumping station.

However, the water authority has been discussing the need for repairs to Lake Purdy Dam for years.

In 1980, the structure leaked approximately 1.5 million gallons of water. per day, according to old BWW board meeting minutes obtained by AL.com. The runoff accelerated rapidly between 2018 and 2019, eventually reaching about 7.6 million gallons. daily, agency records show.

At the time, engineers estimated that rebuilding the entire structure would cost between $75 million and $100 million.

A failure of the dam would prevent BWW from delivering water to the southern end of the city system, engineers told the board in 2019.

Repair project is expected to take nearly four years

Plans call for the extensive renovation and repair project to begin in November and continue until April 2028. Trees will be removed and water will be diverted from the dam.

Crews are also expected to travel 2 miles. of road improvements from Alabama Highway 119 near the Brook Highland neighborhood to the dam site to support construction traffic.

Funding for the project comes from a $171 million federal loan from the U.S. Environmental Protection Agency (EPA) and was authorized through the Water Infrastructure Finance and Innovation Act (WIFIA), part of the Water Resources Reform and Development Act of 2014.

BWW will also use some of the money to replace main service lines that connect homes and businesses to the water mains. This is an important step in reducing the risk of lead exposure for residents and businesses, the agency said.

Along with Inland Lake in Blount County, Lake Purdy is an important source of drinking water for the 600,000 customers in the Birmingham area.