Operation aids in Florida freshwater conservation

Florida does not have a freshwater supply problem. But it does have serious freshwater storage problems.

Palm Beach Aggregates is a core part of South Florida’s solution that could meet freshwater demands for Palm Beach and Broward counties for the next 50 years, and could assist in flood control and Florida Everglades restoration, as well.

Palm Beach Aggregates Inc. (PBA) is located on 4,400 acres near Loxahatchee in western Palm Beach County, about an hour north of Fort Lauderdale. The quarry was opened in 1993 and purchased by PBA in 1997.

“We’re turning our mined-out aggregate pits into freshwater storage reservoirs,” says Albert J. Carbon III, the engineer in charge of the project who has been with PBA for about two years. “Previously I was the city of Fort Lauderdale’s public works director, which includes freshwater management. “So I have been acutely aware of and involved in South Florida’s crucial water storage needs and associated problems for some time.

“Palm Beach Aggregates is in a distinctive position to develop water storage reservoirs due to the unique geologic characteristics (impermeable rock formation not found anywhere else in South Florida) here at our location,” Carbon adds. “This allows long-term surface water storage without significant seepage losses.”

PBA Operations Manager John W. Bates adds: “We are able to pump water out of a mined-out pit and keep it dry with only a few small pumps so we can work there to level the floor, line the upper part of the slanting walls with concrete, and install equipment to operate the reservoir when it is allowed to fill with water again.”

L8 and C-51 reservoirs

Seen here is construction of the inflow station to the L8 reservoir. A similar structure will connect the C-51 reservoir to L8.. Photos courtesy of Palm Beach Aggregates.

So far, PBA has constructed or will be constructing two water storage systems in mined-out pit areas that are located side-by-side: the 950-acre L8 reservoir (so named because it sits adjacent to and is fed by the L8 Canal), and the 2,200-acre C-51 reservoir (adjacent to and fed by the C-51 Canal). The L8 and C-51 canals are part of a canal network used for stormwater management, environmental restoration and drinking water supply.

The L8 reservoir – recently renamed L8 Flow Equalization Basin (FEB) – was built by PBA in 2007-08 and has been operated with a temporary water control system. Currently, a permanent control system (inflow station and outflow pump station) are being constructed. The L8 FEB can store up to 45,000 acre-ft. of raw water and assist in environmental restoration of the Florida Everglades.

The C-51 reservoir’s phase-one construction is expected to start this year and take 24 months to complete. This initial phase will hold about 14,000 acre-ft. and supply 35 million gallons per day of raw water to participating utilities and/or help environmental restoration.

Phase two will hold an additional 46,000 acre-ft. of water. The distance between the C-51 and L8 reservoirs is about 800 ft., so water from C-51 can be easily transferred to L8 through a connecting control structure for additional widespread distribution. C-51 capitalizes on the current construction and engineering work of L8, including intake structure and pumping facilities.

PBA’s operation

The C-51 reservoir will supply 35 million gallons per day of raw water to participating utilities and/or help environmental restoration.

Initially, PBA mines its quarry pits as follows: 8 to 10 ft. of overburden is stripped off. Next are two 9- to 10-ft. layers of lime rock consisting of an upper layer of coral limestone PBA calls “gold rock” and a lower layer of limestone with seashell content called “gray rock.”

These materials are removed with a giant dragline, put through primary impact crushing at the pit location, and then sent on with conveyors for additional crushing and screening. The mined-out pit depth averages 28 to 30 ft.

“Most people think of a mined-out quarry as just a leftover hole in the ground,” Carbon says. “We’re making ours a whole lot more than that.”

Photos courtesy of Palm Beach Aggregates.

Carl Emigh of CME Creative Services Inc., Marion, Ohio, is a freelance writer and marketing communications specialist serving the aggregates, recycling and construction industries. Information for this article is courtesy of Powerscreen.