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Authority Meets Increased Summer Demands with Interim Booster Pump Station

When vacationers flock to southeastern North Carolina beaches in the summer, they use a lot of water. So much, in fact, that for 15-20 days, water demands nearly double.

Summer tourist traffic can account for a 100% increase in water demands during peak vacation season.

This posed quite a challenge for the Lower Cape Fear Water and Sewer Authority, which provides raw water to counties with several beachfront communities. How could the Authority deliver water at appropriate pressures during those peak demand times without investing in infrastructure that may be used only a few days each year?

The solution was an interim booster pump station featuring three diesel-fueled pumps that are rented only for the time they are needed. The system provides the Authority with the ability to deliver 29 mgd of raw water at required delivery pressures, and includes an emergency interconnection between two raw water mains and site infrastructure to accommodate a future, permanent pump station.

The interim station, which came online June 25, "positions the Authority to be of greater service to its customers, and enhances everybody's quality of service," said Don Betz, executive director of the Authority.

The Challenge

The Lower Cape Fear Water and Sewer Authority is a non-profit public agency that constructs and operates water systems located within its service area. Through its 45-mgd Kings Bluff Raw Water Pump Station, the Authority provides raw water to Brunswick and Pender counties, the Cape Fear Public Utility Authority in Wilmington, and two private industries. Average flow is 22 mgd, but the demand soars to 38-42 mgd during the summer.

The site allows for a fourth pump if needed, as well as the future location for the permanent booster pump station.

Eventually, as year-round water needs increase within its service area, the Authority will upgrade the Kings Bluff facility with a new raw water transmission main, a permanent raw water booster pump station, and a 15- to 20-mg ground storage tank. But immediately, the Authority needed to deliver capacity at the required pressure to meet its water supply agreement requirements while planning for a more permanent solution.

Shown here is a fuel cell provided by Mersino, Inc.

An Interim Solution

The interim station is located adjacent to the Authority's 3-mg ground tank on a remote site that has minimal available electrical infrastructure. Therefore, the engineering team opted to use diesel-fueled pumps with a rated capacity of 29 mgd. "The system has all the bells and whistles, although it's located in a very remote location. The noise of the diesel motors won't disturb anything," said Betz.

Michigan-based Mersino, Inc. provided the brand-new pumps, diesel fuel cells and a 480-volt generator, as well as all associated maintenance and upkeep. Rental costs are estimated to be less than $100,000 per year. "The Authority only pays when it utilizes the pumps. Mersino will remove the pumps during the non-peak periods, and reinstall them next year to meet summer peak demands," explained Tony Boahn, PE, regional manager with McKim & Creed, which provided full engineering services.

The diesel-driven raw water pumps are located in a remote area with limited electrical infrastructure.

State Utility Contractors of Leland, North Carolina furnished construction services for the $1.6-million project. Of that total cost, $1.25 million was for site infrastructure that will be used for the future permanent booster pump station, and included an emergency interconnection between Cape Fear Public Utility Authority's 30-inch raw water main and the Authority's 48-inch raw water main.

The interim station's controls are linked to the SCADA system operated by Brunswick County. "The way this station is designed, within 10 minutes of being notified of increased demand for water and pressure, we can provide it. That is exceptional," said Betz.

In addition, the SCADA integration at the interim station will collect data that can be used to assist in the planning and design of the future permanent booster pump station.

"This combination of a good design, a good contractor and brand-new equipment gave us the proven results," said Betz. "It's a great team effort."