OWASA Jones Ferry Road Water Treatment Plant

Originally published in the Fall 2018 issue of NC Currents magazine.

General

The Orange Water and Sewer Authority (OWASA) is a publicly owned agency located in southern Orange County that serves a

population of approximately 83,300. Located in Carrboro, OWASA was established in 1977 to provide drinking water,  wastewater   treatment and reclaimed water to the towns of Carrboro and Chapel Hill and the University

of North Carolina (UNC).

OWASA operates the Jones Ferry Road Water Treatment Plant and the Mason Farm Wastewater Treatment Plant (WTP). The distribution system has 380 miles of water main and includes five water storage tanks with a total capacity of 6.5 million gallons of storage.

History

Prior to construction of the Jones Ferry Road WTP in 1948, there were two WTPs on the campus of UNC. University Lake Reservoir was built circa 1932 and was used to provide raw water to the two WTPs. These WTPs were eventually taken out of service. The Jones Ferry Road WTP was completed in 1950 on a 17-acre site. It included three filters, three sedimentation basins and a production capacity of 3 million gallons per day (mgd). In 1962, the WTP was upgraded with two additional filters and sedimentation basins, which brought the capacity up to 5 mgd. The 1974 expansion brought the capacity to 10 mgd.  Circa 1990, the sedimentation basin capacity was increased from 10 to 20 mgd with the addition of the Superpulsators®. Circa 1993, the administration building, control room and lab were upgraded, and the filter capacity was expanded by 15 mgd with the addition of three filters. In 2002, the plant was upgraded to 20 mgd with two additional filters and an ammonia feed system. The current design flow is 20 mgd with an average daily flow of 7 mgd. 

Process Flow Components

• Three Raw Water Reservoirs and Pump Intakes

• Rapid Mix with Chemical Injection

• Flocculation Basins • Five Sedimentation Basins

 • Continuous Solids Collector System

• Two Superpulsators®

• Ten Dual Media Filters

 • Sodium Hypochlorite Disinfection

 • Clearwell with a capacity of 1.5 mgd 

Raw Water Intake and Reservoirs

The WTP's source water is provided by three reservoirs that include the Cane Creek Reservoir, University Lake Reservoir and Quarry Reservoir. Cane Creek Reservoir has a storage capacity of 3 billion gallons and a pumping capacity of 10.5 mgd. The University Lake has a capacity of 450 million gallons and a pumping capacity of 20 mgd. The Quarry Reservoir has a capacity of 200 million gallons and a pumping capacity of 8 mgd. 

Sedimentation and Filter Operation

One of the unique features of the plant is how the sedimentation process is split between the Superpulsator® and the conventional sedimentation basins. Side One includes five conventional sedimentation basins, treating 2 million gallons each. A TRAC-VAC® sludge collector system removes the accumulated solids from the conventional sedimentation basins. Side Two has two Infilco Superpulsators® upflow clarifiers treating 5 million gallons each. The two clarification processes are operated together to meet system demands.  Clarified water is further treated through 10 dual-media filters with a total surface area of 3,880 square feet. When operated at the permitted filtration rate of 4 gallons per square foot per minute, the filters have a combined capacity of 22.3 mgd. Blowers are used to provide air scouring of the filters. The pipe and filter gallery instrumentation include Hach FilterTrak filter effluent turbidimeters, chlorine residual analyzers, filter effluent flow meters and control valves. A Chem Scan analyzer monitors ammonia monochloramine levels. From each filter console, a manual backwash can be initiated. Standard operating procedure is to perform this operation at the filter console so the operator can monitor the backwash in progress. 

Chemical Feed and Disinfection System

 Coagulation is achieved through the addition of ferric sulfate at the flash-mixing chamber. Liquid caustic (sodium hydroxide) is fed for pH control. A blend of orthophosphates and polyphosphates is added for corrosion control in the piping. In 2002, a sodium hypochlorite and ammonia sulfate feed system was added for chloramine disinfection. This process decreases the concentration of disinfection byproducts (DBPs) and improves water taste. At the Cane Creek Reservoir, sodium permanganate is fed to treat for organics, along with taste and odor. 

Solids Treatment

A solids handling facility, completed in 2001, increased the ability to handle sedimentation solids and filter backwash requirements. A belt filter press and gravity thickener was added to dewater the solids, and 100% of the solids sent to McGill Environmental Systems for composting are recycled. 

SCADA System and Controls

 OWASA installed a Supervisory Control and Data Acquisition (SCADA) system to monitor the plant, reservoirs and distribution system. This system consists of computer monitors, iFix Human-Machine Interface (HMI) software and a communication network that incorporates Modicon programmable logic controllers (PLCs). The SCADA system provides flow-pacing capabilities to control selected chemical feed systems.

 Plant Staff

 OWASA currently employs 22 plant personnel. This includes 15 operations and maintenance staff, three laboratory staff and one administrative employee. In addition to this, all operators are “A” Certified, with one exception. Of special note, since the beginning of operation of the Jones Ferry Road WTP in 1950, there have been only three plant superintendents. 

Awards

The Jones Ferry WTP received the Partnership for Safe Water, Excellence in Water Treatment (Phase IV) Award in 2011. The Phase IV standards have been maintained since 2011, so the plant has been honored with the award for the past seven years. The plant also received the Area-Wide Optimization Program (AWOP) award for the past 7 years. 

Personnel Development Programs

• OWASA offers a mentoring program for employees that elect to participate.

 • Bonus pay for additional certifications.

 • Bonus pay for additional education and educational reimbursement.

• Spot bonus program.

 • Flexible work schedules are available.

 Safety and Health Program

Safety is the number one priority for OWASA: it has employee safety and senior safety committees. OWASA also has a safety ‘time out’ policy. Any OWASA employee that witnesses an unsafe act or process can call a safety time out. The project or process must be discontinued until the safety issue can be addressed and corrected. 

Plant Improvement Projects

 In 2018, the backwash system and filters were rehabilitated. This consisted of new media and wash water troughs. In addition to this, the system was modified so the operator can use either the backwash pump or the system pressure for backwash operation. In the fall of 2018, construction will begin on a rehab of the original concrete structures. This project will consist of a rehab of the five original sedimentation and flocculator basins. In addition to this, influent valves, effluent valves and mud valves will be replaced. In 2019, a rehabilitation project for the University Lake Raw Water Pump Station will begin. This will include an electric and pumping equipment upgrade. OWASA will also build a sodium permanganate feed facility at University Lake. 

For additional information, please contact:

 Ken Loflin, Water Supply and Treatment Manager 400 Jones Ferry Road Carrboro, NC 27510-2001 919-537-4232 kloflin@owasa.org