Control Room

Infilco Superpulsator® 

Front of the main WTP Building

Sedimentation Basins

Front of main building circa 1948

Pipe Gallery

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

Existing Aeraton Basins and  Incinerator Building

New 160 foot Clarifiers- Phase 2

New Tertiary Cloth Filter System- Phase 3

New Bar Screens

New Aeration Basins Construction- Phase 4

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

General History
Located in the central portion of the 
state, the City of Greensboro, formerly Greensborough, was named for Major General Nathanel Greene, commander of the American forces at the Battle of Guilford Courthouse in 1781. It is the largest city  in Guilford County and the surrounding Piedmont Triad metropolitan region, with a current population of approximately 277,000. In addition to the manufacture of textiles and tobacco products, Greensboro is a major regional freight rail hub.

The history of water reclamation in Greensboro began with the construction  of the original 4 mgd South Buffalo Creek Treatment Facility in 1928. Over the next 10 years, the North Buffalo Water Recla-mation Facility (WRF) opened to provide secondary treatment for the northern half of Greensboro. By 1984, the South Buffalo Creek Treatment Facility closed and was replaced by the T.Z. Osborne WRF. The North Buffalo WRF was decommissioned in October 2017 and converted into a transfer pump station. All of the wastewater for the City is now treated at the T.Z. Osborne WRF.  

The T.Z. Osborne WRF is a 40 mgd-rated advanced wastewater treatment facility. The plant treats both domestic and industrial wastewater from the City and the surrounding community. In addition, the plant influent consists of approximately 90% domestic and 10% industrial wastewater. The plant operates with an average daily flow of 28 mgd and a peak flow of 100 mgd and the annual operating cost is $11 million. 

The plant’s effluent discharges into 
South Buffalo Creek, which originates in Guilford County. South Buffalo Creek is a major headwater stream in the Cape Fear Watershed and affects downstream drinking water supplies, including Jordan Lake. 

Currently, the City of Greensboro Water Resources Department operates the T.Z. Osborne WRF and sewage collection system that collects and transports sewage to this plant. The collection system is made up of approximately 99,797 connections, 1,629 miles of gravity lines, 49 pump stations, and 88 miles of pressurized sewage force mains.  

Key Treatment Information:

 The current wastewater process is a two-stage activated sludge treatment process, and the primary treatment units consist of:

• Four Huber mechanical bar screens (new)
• Four influent pumps
• Two grit classifiers
• Two flow equalization tanks
• Six primary settling tanks
• 12 aeration basins
• 10 secondary settling tanks
• Three centrifuges
• Six tertiary Aqua Diamond cloth filter basins (new)
• One sodium hypochlorite disinfection system with six contact chambers
• Six cascade aeration
• Two discharge outfall pipeline

SCADA System

 This system consists of multiple computer workstations that utilize GE CIMPLICITY Human Machine Interface (HMI) software. The network communication system incorporates GE programmable logic controllers (PLCs), allowing the staff to monitor and control plant processes from the main control room located in the operations building.

Solids Treatment and Biosolids Management
The T.Z. Osborne WRF incinerates sludge in a fluidized bed incinerator. Before incineration can take place, the sludge 
(which is 96% to 98%) must be de-watered. The first step in this process is to mix a polymer solution with the liquid sludge. The polymer is a flocculant and is used to “charge” the sludge particles, so they will tend to clump, or floc, making it easier to separate the solids from the water. After being treated with the polymer, the sludge is pumped into centrifuges where centrifugal force is used to remove the excess water from the sludge. This drier sludge is referred to as sludge cake. Although the sludge cake is still about 70% water, it is now ready for incineration.

Sludge Incineration
The sludge is burned in a fluidized bed incinerator. This incinerator has one hearth, which is equipped with openings to allow air to be blown through the hearth. The flow of air raises and suspends a layer of sand above the hearth and the sand is heated to approximately 1,400°F. As the sludge is pumped into the incinerator, it comes in contact with the fluidized bed 
of hot sand and results in instantaneous evaporation and then combustion occurs. The same airflow that suspends the sand blows the ash out of the incinerator and into the air scrubbing system where the ash and some of the fine sand is removed. A sand silo provides "make-up" sand and replaces what is removed with the exhaust from the incinerator.

Incinerator Ash Disposal
Water containing ash and sand from the incinerator air scrubbing system is pumped to the ash clarifier. After the ash and sand mixture is allowed to settle in the clarifier, it is pumped to the ash press, where porous fabric belts are used for dewatering. The dewatered ash and sand mixture is hauled to the City’s landfill for disposal.

Personnel 
The T.Z. Osborne staff consists of three sections: operations, maintenance, 
and an industrial waste/lab along with administrative staff. The operations section has 23 full-time employees and two roster employees. The maintenance section has 20 full-time employees and one roster employee. The industrial waste/lab section has eight full-time employees and one roster employee. There are three administrative staff employees and there is a 10-hour work schedule for maintenance, rotating weekends for operations, and flexible work schedules for other staff.

Personnel Development
The staff is provided with the opportunity to work towards all relevant certifications in their field, from biological treatment  to physical/chemical treatment, maintenance technician, pre-treatment, collections and distribution, and lab certifications. In addition, the WaterMARK supervisor training program is provided for all employees.

Safety Program
A divisional Safety Committee exists, and the members participate with the department’s Safety Committee. The department has an incentive program that gives annual leave for participation in safety-related training/committees, along with reporting near misses and helping out with a safe work environment.

Current and Future Expansion 
The T.Z. Osborne WRF is currently under expansion to be upgraded to a 56 mgd biological nutrient reduction wastewater facility. Construction started in 2014 and will continue through 2020. The expansion construction packages are as follows:

Package One - addressed current  and future hydraulic capacity issues  at the North Buffalo WRF. The specific improvements for Package One included conversion of an existing aeration basin at the North Buffalo WRF into a flow equalization basin and adding increased transfer pumping capacity. Improvements at the T.Z. Osborne WRF are necessary to receive the pumped flow from the North Buffalo WRF and include a new flow equalization basin, equalization diversion structure, and flow control/metering vault. The North Buffalo WRF treatment facilities downstream of the influent pump station will be demolished or abandoned. 

Package Two- hydraulically expanded the T.Z. Osborne WRF for treating up to 56 mgd under the current nutrient limits and included improvements to pass the peak future flow with the North Buffalo WRF decommissioned. The improvements for Package Two include new membrane-diffuser grids in the existing aeration basins; two new single-stage blowers; and three new 160-foot diameter clarifiers with associated distribution and return activated sludge pumping, new yard piping for increased flow, and electrical improvements, including a new generator.

Package Three – increased final discharge and filtering capacity to complete hydraulic expansion of the T.Z. Osborne WRF to 56 mgd. The improvements for Package Three include new Aqua Diamond Cloth tertiary filters, two new chlorine contact tanks, modifications to the existing chemical feed facilities, and an additional outfall pipeline. 

Package Four – will add biological nutrient removal (BNR) capacity to 
the plant to meet nutrient removal requirements of the Jordan Lake Rules at the increased capacity of the plant. The improvements for Package Four include construction of six new aeration basins, modifications to the existing aeration basins, including new baffle walls, post-anoxic zone mixing, nitrified recycle, and associated electrical improvements. 
Additional major projects have included the replacement of four existing mechanical bar screens with four new Huber mechanical screens and an additional non-potable water pump station.

After a thorough review of the required BNR processes, the age of the North Buffalo WRF, the costs of the projects, and Greensboro’s unique transfer capabilities, a workgroup of Greensboro Water Reclamation staff and engineering consultants made the decision to close/decommission the North Buffalo WRF and consolidate all wastewater treatment at the T. Z. Osborne WRF. 

The City of Greensboro developed a sequenced closure plan to ensure that 
the North Buffalo WRF site was properly transitioned from an active wastewater treatment facility to a wastewater transfer pumping station. The plan outlined the activities and responsibilities of each section of the Water Reclamation Division and included a master schedule. This plan was very successful and resulted in the decommissioning of the North Buffalo WRF with no major issues. It was a total team effort that made the closure plan successful.
As part of the construction procurement process, Package Three and the Electrical Buildings in Package Four, along with the non-potable pump station, were constructed using the construction-manager-at-risk 
(CMAR) project delivery method. Using 
the CMAR method enabled the City of Greensboro to breakdown construction work packages to small enough sizes to utilize minority, women, and local contractors that would not normally be able to bid or work on this type of specialized work. The City also used mentor/protege relationships to help build capacity and train contractors for future work opportunities. 

For additional information,  please contact:
Elijah Williams, PE – 
Water Reclamation Manager
2350 Huffine Mill Road
Greensboro, NC 27402-3136
(336) 373-4632
elijah.williams@greensboro-nc.gov
www.greensboro-nc.gov

Smithfield – Tar Heel Facility WWTP. Note the
90,000,000-gallon effluent storage basin to
the right.

Aeration basins and anaerobic lagoon
in background

Routine maintenance and repairs made to Aeration Basin 1 during Labor Day Weekend 2017.

Waste solids being dewatered on a two-meter belt press.

Clarifier effluent polishing/utilizing a DAF Unit.

Tim Weaver with Fuzzy Filter media.

Jacob Davis performing a bug count in the Lab.

The Tar Heel Facility WWTP next to the small package WWTP – the Sanitary Waste Package Plant.

Originally published in theWinter 2017-2018 issue of NC Currents magazine.

General

In 1992, Virginia-based Smithfield Foods extended its operations into Bladen County in the southeastern section of North Carolina. Since that time, the Tar Heel facility has expanded into the largest pork processing facility in the world, currently employing about 4,600 associates in the daily production of Smithfield’s line of quality pork products. The production facility typically works five days a week, harvests 34,000 heads of hog per day, and is ISO 14001 certified. The Environmental Department of Smithfield – Tar Heel currently has 24 staff members, with three management and clerical staff, six operating the pretreatment unit and solids handling facilities, six operating the wastewater plant (WWTP), three operating the reuse and potable well water system, three operating the potable surface water plant, one dedicated maintenance mechanic (with production plant maintenance assistance, when required), and two lab personnel. This allows for 24/7/365 monitoring of all environmental operations within the facility. The WWTP has a “flow equalized” design flow of 3.0-mgd (monthly average) and the plant’s effluent discharges into the Cape Fear River Basin. 

Key Treatment Processes Include: Pretreatment:

 • Three rotating drum screens

• One 250,000-gallon dissolved air flotation (DAF) unit

• Two three-phase centrifuges (solids, grease, centrate)

WWTP:

 • One 90-MG effluent storage basin

• Two 13-MG anaerobic lagoons (26-MG capacity)

• One biogas system (biogas sent to feed three boilers for steam to the production facility)

• Three anoxic basins

• Three 1-MG aeration basins and one 2-MG aeration basin (5-MG of aeration capacity)

• Four clarifiers

• One clarifier effluent polishing DAF unit

• Four Schrieber Fuzzy Filters

• Dual disinfection - chlorination (sodium hypochlorite)/dichlorination (sodium bisulfite), and ultraviolet (UV) light

Solids Handling:

  • One 500,000-gallon WAS sludge holding tank

• One two-meter belt press

Water Reuse:

 • Two flocculators

• Two lamella plate clarifiers

• One Schrieber Fuzzy Filter

• One chlorine contact chamber

Treatment Processes

 The WWTP operates in concert with the main facility’s production schedule. During an average production day, the WWTP can expect to receive a flow of up to 4.6-mgd of production water, with flow decreasing on the weekends to around 600,000 gallons per day.

 The recovered processing water first flows to our pretreatment unit, where it is screened to remove any bits of meat or other solids. Next, chemicals (typically an alum-based coagulant and polymer) are added and the water is passed to a DAF system.

The system acts as a reverse clarifier, causing the solids and grease to rise to the top, where they are skimmed off. The skimmings are sent to a three-phase centrifuge, which spins the skimmings and separates out solids, grease, and the leftover centrate. The solids and grease that are recovered are then sent to the rendering facility and sold as a product, and the centrate is recycled back to the raw water for another pass. Next, the DAF effluent is pumped to the WWTP, where it is equitably split between two covered anaerobic lagoons. These lagoons process the wastewater using anaerobic bacteria and convert a portion of the remaining ‘food’ into methane gas. We typically experience a 65 to 70% drop in chemical oxygen demand (COD) through this process. The methane is utilized to fire three boilers that supply steam to the production facility, displacing the equivalent of $30,000 of natural gas monthly, on average. These lagoons also serve as flow equalization for downstream processes.

During the production week, we utilize a flow control valve and allow water to accumulate in the anaerobic basins. During the weekend when we have lower influent flows, the water level decreases. This allows a more steady state flow throughout the downstream treatment processes. As the water moves forward, we go into our aerobic biological treatment and biological nutrient removal processes. The anaerobic effluent is distributed to the anoxic basins and is mixed in with aerobic bacteria by way of return activated sludge (RAS) from the clarifiers and mixed-liquor return (MLR) from the aeration basin effluent. The anoxic effluent is then distributed to the aeration basins, which utilize aerobic bacteria to remove the remaining ‘food’ via biochemical oxygen demand (BOD) and COD.

 Excess solids are sent to a 500,000-gallon aerated storage tank and are dewatered using a two-meter belt press. The solids are sent to a landfill as a bacterial supplement to enhance methane production. The methane is then used by the landfill to generate power.

 The WWTP has limits on both ammonia and total nitrogen in our discharge. In order to satisfy both requirements, we go through the process of nitrification and denitrification. Nitrification occurs in the aeration basins at the same time the ‘food’ (BOD, COD) is being removed. A special group of aerobic bacteria (most notably nitrosomonas and nitrobacter) work to convert ammonia (NH3) to nitrite NO2 and finally to nitrate NO3. In the aeration effluent  there is little to no ammonia present, as it has been converted to nitrate. Nitrate is a nitrogenous compound, however, and contributes to the amount of total nitrogen in the discharge.

 In order to decrease the total nitrogen, high nitrate aeration effluent is recirculated (mixed liquor return) back to the anoxic basins. The anoxic basins have mixers that mix these solids with the anaerobic effluent in basins that have a low dissolved oxygen (DO). The bacteria look for air to breathe and when they find none, they start stripping the oxygen molecules off the nitrate NO3, thereby causing nitrogen to be released as a gas and dissipated to the atmosphere. For this reaction to occur, there also needs to be a carbon source applied to the anoxic basins. Although this is an extremely simplified version of the denitrification process, when the anaerobic effluent doesn’t have enough carbon, it can supplement with methanol.

From there, sedimentation occurs in four round clarifiers. The solids that settle are pumped back to the aeration basin to allow the bacteria to continue to do their work. The clarifier effluent can run either to tertiary processes that help polish and disinfect the effluent prior to discharge, or it can be pumped to a small-footprint reuse system. The tertiary processes include an additional DAF unit to remove any solids that might still be present. DAF effluent is then filtered with four Fuzzy Filters, which utilize small proprietary media resembling small cotton balls.

 Disinfection is accomplished using a sodium hypochlorite feed just prior to using the Fuzzy Filters in order to maximize  time and to prevent bacteria buildup in the filters. The chlorinated filter effluent goes to a re-aeration basin to boost DO levels prior to discharge, and then sodium bisulfite is added to the reaeration basin effluent to dechlorinate. The last stage of treatment is UV disinfection – we have three banks of 10 modules with eight bulbs each, for a total of 240 UV bulbs – and treated water is then discharged to the Cape Fear River. If for any reason the effluent does not meet our permit requirements, we can divert the entire effluent flow to the effluent storage basin. This flow is then filtered and reintroduced to the WWTP for further treatment.

 We are also fortunate to have a reuse system that is capable of additional polishing up to 2 mgd of clarifier effluent for reuse in the WWTP in non-product contact areas. The system is designed after a small footprint surface water plant and is comprised of two flocculation tanks, to which alum and polymer are added; two lamella plate clarifiers; fuzzy filtration; and chlorine disinfection in a chlorine contact basin that allows for at least 30 minutes of detention time at design flow. This system also has the ability to polish up plant effluent for discharge into the receiving stream, when needed, to help meet treatment objectives.

 Due to the requirement for the reuse system to separate out sanitary streams, we have a small package WWTP that treats all of our sanitary (bathroom and cafeteria) waste, located next to the Tar Heel Facility WWTP. The waste solids from this unit are transported to a municipal facility to maintain this requirement, and the effluent is blended into our main plant final effluent just prior to disinfection. This unit was just replaced last year. We also have a state-certified lab that handles most of our lab needs.

Challenges and Unique Features

 With so many loops and further treatment options, any upset within the production facility or any upstream process effects everything downstream of that process, usually by applying more ‘food’ than the system is designed to handle. Sometimes this is a real balancing act, facilitated by many features that are unique to this plant. The effluent storage basin allows for us to send the entire plant flow to storage and further treatment in case of plant upset or issues. We recently acquired a DAF unit to polish clarifier effluent and decrease loading on our Fuzzy Filters. We also have the ability to utilize the reuse system to polish the effluent, if needed.

 Although not typically considered during a discussion of WWTP operations, we have found that our potable water supply can have a very large impact on wastewater operations – mainly due to temperature variances. The original deep-well system is comprised of eight source wells and provides water that is fairly consistent in temperature. In 2013, when the Bladen Bluffs Surface WTP was added as an additional water source, it was discovered that the significant seasonal temperature changes had the ability to impact wastewater treatment. If the water gets too cold or too hot, anaerobic activity becomes inconsistent and leaves the potential for ‘food’ to not get processed optimally.

 Additionally, ammonia conversion within the aeration system can be negatively affected. To mitigate potential issues, the temperatures are carefully monitored, sometimes with favor given to the well system water to buffer out these temperature variations.

Personnel

 Smithfield has been very proactive in training, certification, and cross training within all areas. Currently there are: 13 Grade IV Operators, three Grade II Operators, three Grade I Operators, six Land Application Operators, two Maintenance 2 Operators, two Collection 1 Operators, three A Well Operators, two B Well Operators, five C Well Operators, three A Surface Operators, five C Surface Operators, seven Physical Chemical 1 Operators, and two Collection System Operators.

Training

 Annually, Smithfield sponsors and participates in holding state-approved continuing education training classes in both water and wastewater subjects. Usually there are four classes per year, and these training events are open to outside participants for free. Three of the staff also actively participate in teaching at NC Water and Wastewater CE Training Classes and NC Water and Wastewater Certification Classes.

Awards

 • Timothy L. Weaver – Wilbur E. Long Industrial WWTP Operator of the Year 2010

• Robert “Buddy” Harris – Wilbur E. Long Industrial WWTP Operator of the Year 2013

• Ronald Mains – NCWOA C Well Operator of the Year 2013

• Dwayne Russ – NC AWWA-WEA Industrial WWTP Operator of the Year 2014

Contact Information

 Tim Weaver

Wastewater Superintendent

Tel: (910) 862-5248

tweaver@smithfield.com   

Sedimentation Basins and WTP Operations Building

Raw Water Pumps at Pump Station # 2

Operations Staff

Filter Pipe Gallery

Filter Gallery

Original Raw Water Pump Station and Intake

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

General

The City of Shelby is located in
Cleveland County and has a current
population of approximately 20,323.
Known as the “City of Pleasant Living,”
Shelby is located in western North
Carolina about 65 miles west of Charlotte
along US 74. Shelby was incorporated
in 1843 and named for Colonel Isaac
Shelby, a Revolutionary War hero at the
nearby Battle of Kings Mountain.

The City of Shelby is a full service utility
community. The Shelby utilities system is
a municipally owned and operated public
utility system that provides residential,
commercial, and industrial customers with
water, sewer, electric, and natural gas.
The City currently operates one
WTP and one WWTP. The WTP serves
the City of Shelby and nearby Boiling
Springs. The distribution system has
220 miles of water line with two pressure
zones and includes four elevated water
storage tanks with a total capacity of
2.25 million gallons (MG) of storage.

The source water for the water treatment
plant is the First Broad River, which is a
tributary within the Broad River Basin. The
river originates in the foothills of the South
Mountains. The City of Shelby also has a
secondary intake at the Broad River.

History

In 1953, construction began on the
original WTP that included four filters
and a production capacity of 4.0 million
gallons per day (mgd). J.N. Pease was the
consulting engineer for the project.
In 1959, plant upgrades at the WTP
included the addition of four filters, and
increased the production capacity to
8.0 mgd. J.N. Pease was the consulting
engineer for this project as well.
In 1992, plant upgrades at the WTP provided two additional sedimentation basins, conversion to dual filters, new raw water intake, and new chemical storage and brought the production capacity to 12 mgd. The daily flow is approximately 6 mgd. McGill Associates was the consulting engineer for the project.

The Shelby WTP is ISO 14001 Environmental Management System certified, becoming one of the first
WTPs in the state of North Carolina to
achieve this certification. Both the water
treatment plant and the First Broad
WWTP facilities are ISO 14001 certified.

Process Flow Components

• Two permanent raw water intakes
• Influent screening
• Five (5) raw water pumps
• Three raw water storage lagoons –
19.0 MG
• Rapid mix – chemical injection
• Flocculation –
12 vertical flocculation mixers
• Sedimentation with tube settlers
• Dual media filtration – eight filters
• Chlorine disinfection
• Clearwell – 8 mgd
• High service pump station –
six pumps
• One booster pump station with
new booster station in the process of bidding
• One new 0.750 MG tank under construction

Raw Water Intake Structure and Reservoirs

The primary water source is the First Broad River with a permitted withdrawal rate of 18 mgd. Raw water is withdrawn from one of two raw water pump stations and then pumped to a series of three raw water reservoirs for temporary storage. Capacity of the two lower reservoirs is 14 MG. The upper reservoir provides an additional 5 MG of storage. Flow is then gravity fed from the upper reservoir into the rapid mix chamber at the head of the plant.

The secondary water source is the Broad River near Boiling Springs, with a permitted withdrawal rate of 9 mgd. This 30-inch line was installed as an emergency backup source after the drought of 2002.

Flocculation, Sedimentation, and Filter Operation

 
After the water leaves the rapid mix chamber, it enters the flocculator basin where the coagulation chemical (See Chemical Feed and Disinfection below) is further mixed, allowing the “floc” to Sedimentation Basins and WTP Opeerations Building Raw Water Pumps at Pump Station # 2 24 NC Currents Spring 2018 fully form. There are six vertical type flocculators in use per side, for a total of 12. Each flocculator turns at a lower speed so as not to break up the formation of the “floc.”

After the “floc” has been formed, the flocked water is drawn into the sedimentation basins allowing formed “floc” to settle or drop out. The majority of the “floc” settles here, reducing the load on the filters. The sedimentation basins also incorporate tube settlers that decrease settling time and improve performance. The settled water enters the filters from the sedimentation basins where the remaining “floc” is removed. There are eight filters for filtering settled water. These are Roberts Filter dual media filters comprised of anthracite, sand and gravel, doubling the filtering capacity from 2 ft2/min to 4 ft2/min from a conventional sand filter. The filters are also equipped with wheeler bottoms, rotary surface sweeps, and washwater troughs. The pipe gallery instrumentation includes filter effluent turbidimeters and flow meters. The original marble filter consoles are located above the pipe gallery on the main floor of the filter building. The original controls have been upgraded to electronic digital controls.

From each console, a manual backwash can be initiated. Standard operating procedure is to perform this function at the filter console so the operator can see the backwash in progress.

Chemical Feed and Disinfection System

 Coagulation is achieved through the addition of aluminum sulfate (alum) at the flash mixing chamber just prior to the flocculation basins. In addition to this, sodium hydroxide (caustic soda) is added at the flash mixing chamber to adjust the pH.

 Pre-chlorination is fed prior to the filters and post-chlorine disinfection occurs after filtration and prior to the 8-MG clearwell. The clearwell provides adequate water storage and ensures the required chlorine contact time to disinfect potential pathogens.

 In addition to this, carbon is added for taste and odor and ortho-phosphorus is added to provide a protective coating along the interior of the distribution system piping. Finally, hydrofluosilicic acid (fluoride) is added for protection of the consumer’s dental enamel.

 The chemical additions, from raw water to distribution, are tested in the lab, 24 hours a day, 7 days a week. Tests include pH, chlorine, turbidity, hardness, alkalinity, and fluoride.

SCADA System and Controls

 
Prior to 1992, the plant was equipped with a control panel with circular chart recorders and manual switches and indicator lights. In 1992, the plant installed a QEI QUICS supervisory control and data acquisition (SCADA) system to monitor the plant and distribution system. This system is still in use today but is being phased out to make room for a newer SCADA system. This system consists of computer monitors, Rockwell Human Machine Interface (HMI) software and a communication network that incorporates Allen Bradley programmable logic controllers (PLCs). The future plant upgrade includes plans to install automation of the filters in Phase II of the WTP upgrades.

Plant Staff

 
The WTP currently employs a total of 11 plant personnel, including seven certified operators and four facilities maintenance workers. All of the operations staff is trained to run the required laboratory analyses.

Personnel Development Programs and Certification Programs

 
The City offers continuing education classes to their employees and pays for all training and certifications for operators. In addition to this, the City provides cross training of staff for those interested in career development.

Challenges

 
Drought of 2002
The drought of 2001-2002 resulted in the First Broad River running dry. The City was able to maintain service through innovative cooperation of City staff and other municipal governments. From this process, the City began the planning of improvements of the raw water capabilities and partnered with Cleveland County to install a new raw water line to the Broad River. The Broad River Secondary Intake involved the construction of a 30-inch waterline from the Broad River southeast of Boiling Springs to the City of Shelby WTP. Since this installation, the water line has not been activated but is available for water supply emergencies. As a result of this drought, the City improved drought and emergency response plans for the future.

Loss of Textile Industry – 1990s
The large textile base dwindled in the 1990s, resulting in significant water sales decline that reduced capital funds for plant and system improvements. The City began to look at ways to cut costs and begin the process of attracting new manufacturing to Shelby. The City also worked very closely with Cleveland County to develop this approach. Through funding opportunities and improved water and sewer infrastructure in Northwest Shelby, the City
purchased properties with the County to develop the Foothills Commerce Center Industrial Park. Since 2010, Shelby has been able to attract a diverse manufacturing base of companies that has resulted in the creation of jobs, increased tax base and increased water and sewer revenues.

Some of these include:
• Schletter
• Clearwater Paper
• KSM Castings
• IVARS
• Greenheck Operations Staff

• Mafic
Due to this resurgence of industry, the finished water demand has increased from an average of 4.0 mgd to 6.06 mgd. Finished water demand is expected to exceed 7.0 mgd in 2019 with the Clearwater Phase II Expansion.

Future Plant Expansion

 
Since 2010, the City has developed a Water and Sewer Asset Management Plan and also conducted a thorough evaluation of the WTP. The 2016 plan has established three phases of water plant upgrades totaling over $20 Million. In 2017, the City and its consulting engineer, HDR of the Carolinas, began design for the Phase I improvements, with construction to begin in 2019. This will include:
• New clearwells – existing
clearwell to be abandoned
• New high service pump station
• Filter valves replacement
• Building improvements –
structural and ventilation

Summary

 
The City of Shelby WTP has experienced its fair share of challenges over the last 20 years. The loss of textile manufacturers in the 1990s and the 2002 drought were huge challenges for the water treatment and maintenance staff. However, things continue to improve with the resurgence of new businesses and the implementation of a drought and emergency response plan. Staff will continue to make periodic updates to the City’s Water and Sewer Asset Management Plan to continue to plan and implement infrastructure improvements and evaluate potential hurdles associated with utility management.

The water plant staff has also worked diligently to attain and maintain their ISO Environmental Management System certification. They are proud of this accomplishment and for the job that they perform every day to bring safe and quality water to the City of Shelby.

For additional information: Contact:
Michael Mull - Water Plant Supervisor/ORC
Phone: (704) 484-6885
mike.mull@cityof shelby.com

North Fork Water Treatment Plant

North Fork Water Treatment Plant Operations Building

Pipe Gallery

Filter Consoles

Filter Building

SCADA System

Chemical Feed Building

Originally published in the Fall 2017 issue of NC Currents magazine.

General

The City of Asheville is located in
Buncombe County and has a current
population of approximately 124,300. The
City of Asheville, known for its tourism,
is home to the Biltmore Estate and is
nationally known for its craft brewery
industry. Access to the Blue Ridge
Parkway and many scenic parks are just a
short drive from the city.

The City of Asheville currently
operates three publicly owned water
treatment plants. The North Fork and
William DeBruhl Water Treatment Plants
use direct filtration to treat water from
pristine reservoirs, which are surrounded
by 20,000 acres of limited access
watershed. The William DeBruhl Water
Treatment Plant (WTP) draws water from
the 500-million-gallon capacity Bee Tree
Reservoir, while the North Fork WTP
draws water from the 5.75-billion-gallon
capacity Burnett Reservoir.

Asheville Water Resource has 58,198
service connections within the City of
Asheville and Buncombe County. The
water system is designated a “Class
A” system that is permitted to serve a
population of 124,300.

The water system serves an area of
183 square miles, and has 1,681 miles of
water line, 32 water storage tanks,
37 pumping stations, and three water
treatment facilities, with a capacity to
produce and deliver 43.5 million gallons of
water per day.

The North Fork WTP has a design flow
of 31 million gallons per day (mgd) and
operates with an average daily flow of 15
mgd. The maximum daily flow is 16.9 mgd.

History

Water System Improvements: 1948-1967
The original water supply dates back to
1903. In 1951, construction began on the
Burnett Dam and Reservoir. In 1955, the dam
was completed and the reservoir filled. The
resulting reservoir was completed at the cost
of $2.5 million, with 5.7 billion gallons of water
storage capacity and increased water security
for the Asheville/Buncombe County area.

This provided water to the distribution system
through two 16-inch lines, and a 24-inch line.
The Bee Tree and North Fork WTPs treated
their respective waters without filtration.
In 1960, the City began to plan for
increased capacity from the North Fork
WTP by adding a 36-inch water line. In
1963, construction of the 36-inch pipeline
was completed. In 1967, the City began
fluoridation of the water system.

Water System Improvements: 1978-1992
In 1976, construction began on the new
North Fork WTP, which included the
addition of filtration. Four filters were added
giving the North Fork WTP a production
capacity of 25 mgd.

In 1992, plant upgrades at the North Fork
WTP added two additional filters and brought
the production capacity to 31 mgd.

Process Flow Description

Key Treatment Information

1 – Intake tower – three intakes
@ 20’, 50’, 80’
1 – Flocculation basin
6 – 722 sq. ft. filters
1 – Sodium bicarbonate feed system
1 – Sodium hypochlorite feed system
1 – 5 MG clearwell
5 – Chemical injection points

Raw Water Reservoir & Intake Structure

Filter Operation

The Filter Basins include six dual-media filters that are made up of anthracite, sand, gravel and an air scour backwash system. Each filter has an area of 722 square feet and a flow rate of 5 gpm/SF and is equipped with an airscour system  and washwater troughs. The pipe gallery instrumentation includes filter effluent turbidimeters and flow meters. Six filter consoles are located directly above the pipe gallery on the main floor of the filter building. From each console, a manual or automatic backwash control can be initiated via a touch screen graphic display. Automatic backwash can also be initiated from the SCADA system in the operations building, but standard operating procedure is to perform this function at the filter console so that the operator can see the backwash in progress.

Chemical Feed and Disinfection System

Coagulation is achieved using aluminum sulfate prior to the filters. Pre- and postchlorination is achieved using 12% sodium hypochlorite. Post-chlorination occurs after filtration and before the clearwell to allow for the correct CT ratios. The 5 MG clearwell allows time for contact and plant response if high demand occurs (fire, line break, etc.).

Sodium Bicarbonate is added to the treated water to raise the alkalinity to approximately 25 mg/l. caustic soda is added to adjust pH, and zinc orthophosphate is added to provide a protective coating along the interior of the distribution system piping. Finally, fluoride (hydrofluosilicic acid) is added to protect dental enamel.

Solids Treatment

All solids are processed through three tiered lagoons. Backwash water enters Lagoon #1 and flows through to an effluent structure, then enters Lagoon #2. Water enters Lagoon #2 and flows through to an effluent structure then enters Lagoon #3. Lagoon #3 is the largest lagoon and slows the water considerably before it exits through a parshall flume to record and track effluent flow from this system. As backwash waters flow through this tiered system and lose velocity, solids settle out and form a sludge blanket. Primary settling occurs in Lagoons #1 and #2. Typically, sludge is removed from Lagoons #1 and #2 on an annual basis. In 2017, 675,000 gallons were removed from the lagoons. This sludge is taken to the Metropolitan Sewage District and discharged into their ash basin for later treatment. Removal takes approximately five days. Currently, the plant does not have a biosolids program.

SCADA System and Controls

The original WTP built in 1978 was equipped with a control panel with analog instrumentation and a graphic display panel. The expansion in 1992 replaced the panel with a SCADA system. This system consists of multiple computer monitors, Human Machine Interface (HMI) software and a communication network that incorporates programmable logic controllers. This allows the staff to monitor and control plant processes with transducers and actuated valves that will maintain levels within the flocculation basin and filters. Backwash cycles are automated and can be performed in either automatic mode or manual mode.  

The emergency generator and switching gear are designed to start the generator and transfer the WTP to the emergency power source in the event of a power failure. When power returns to the grid, the switching gear senses the availability and begins a time-closed transition switch over. If the grid remains stable for 30 minutes without interruption, the WTP will transfer back to the grid. This transfer is seamless because of paralleling and the closed transition.

The North Fork WTP has two raw water pumps that are run by variable frequency drives. Each, when activated, will operate off a transducer signal to maintain the level in either the flocculation basin or the filters. 

Personnel Development Programs and Certification Programs

Asheville Water offers continuing education classes to their employees. In addition to this, they provide access to professional organizations such as AWWA and NCWOA. A more formalized career ladder for the City of Asheville Culture of Leadership is expected in the future. 

The following certifications are offered for the plant staff

• Surface operator certification
• Distribution certification
• Backflow certification
• Numerous lab certification
• Physical Chemical 1 certification 

Plant Safety and Health Program

Currently, Asheville Water provides basic safety training at the plant level with opportunities for more in-depth training from the City’s Risk Department and Water Administration. They have an individual who is working to provide more training opportunity for all Water Resources Department divisions. 

Awards

• Area Wide Optimization Program
• Clean Air Compliance Award 

Unique Features

• History of the water system – Providing water to Asheville as early as 1903
• Size and quality of the watershed and water (20,000-acre controlled watershed)

Wildlife

The plant sits on the lower portion of a 20,000 acre watershed. It has abundant wildlife living on acreage surrounding the facility. Wildlife such as deer, turkey, bear and eagles nesting can often be seen.

Future Expansion

 The last expansion occurred in 1993 with the addition of two new filters, which increased the WTP capacity from 25 mgd to 31 mgd. The plant currently has excess capacity, and there are no plans to expand it in the near future. The focus is on maintaining, renewing and modernizing existing facilities. Since a biosolids plan does not exist at present, lime stabilization or some other method to deal with the sludge that the facility generates will need to be considered in the future.

Contact Information

Bill Hart, Water Plant Supervisor

3374 North Fork-Left Fork Rd.

Black Mountain, NC 28711

Phone: 828-271-6101

bhart@asheville.gov

West Brunswick Water Treatment Plant

Oxidation Ditches

Tertiary Disc Filter System

ATAD Reactors

Reuse Pump Station

SCADA System

Originally published in the Spring 2017 issue of NC Currents magazine.

General

Located along the coastal portion of the
state, Brunswick County borders the Cape
Fear River to the east and South Carolina
to the southwest. It has a population of
approximately 123,000 people and is the
fourth largest county in NC by geographic
area. The Cape Fear River and its offshoot,
the Brunswick River, provide access to the
Atlantic Ocean.

Brunswick County operates six
wastewater treatment facilities (WWTF), the
largest being the West Brunswick Regional
WWTF, which is a 6.0 mgd non-discharge
facility. The facility was placed into service
in 2006 as a regional facility to serve
Brunswick County, Oak Island, Holden
Beach and Shallotte. Additionally it treats
flow from Southport and Ocean Isle Beach.
The facility was originally permitted for
3.0 mgd, but with the unprecedented
growth in the area, it was expanded to
6.0 mgd in 2009.

There are 54 lift stations associated with
the West Brunswick WWTF. The collection
system is comprised of low-pressure sewer,
vacuum, and some gravity filters. The facility
receives flow from as far as 25 miles away

Operations

The West Brunswick Regional WWTF
serves a population of approximately
55,000, but due to the geographic region,
it can see high tourist-driven flows in the
summer months. The wintertime flow
averages approximately 2.6‑2.8 mgd.
Summertime flows average 3.6-3.8 mgd,
with a maximum daily rate of over 7 mgd
(storm-related event). The facility’s annual
operating budget is approximately $3 million
and includes both the WWTF and all
dispersal sites (discussed below).

The key treatment processes include:
(4) Equalization basins
(3) Parkson bar screens
(2) Grit removal systems
(4) Lakeside Equipment oxidation ditches –
1.5 mgd each
(4) US Filter TowBro clarifiers
(4) Kruger tertiary disc filter systems
(1) Reuse pump station consisting of
6 pumps ranging from 100 to 150 HP
(1) Lakeside Equipment septage
receiving station

Solids Handling

The solids handling process consists of
two gravity belt thickeners followed by four
auto-thermal thermophilic aerobic digestion
(ATAD) reactors (Thermal Process Systems)
and an ATAD storage tank. The facility is
permitted for up to 500 dry tons per year
of biosolids disposal. Brunswick County
administers its own land application
program and contracts with Bio-Green
to handle all sludge hauling and disposal
of biosolids from the facility. The plant
produces a Class A product that is provided
to local farmers for fertilization.

SCADA

 
The entire facility is automated using a programmable logic controller (PLC)-based control system. The system is based around Schneider Electric Quantum and Momentum PLCs. The monitoring is based on Citect HMI Graphics. The department (encompassing both sewer and water) has an extensive SCADA system that requires a full-time SCADA programmer.

Disinfection

Reuse Water Dispersal

 
1. Drip Irrigation – 1.722 MG, 497.32 acres of dedicated drip irrigation, 99 million gallons of wet weather storage. This equates to over 1 million feet of drip irrigation tubing!

2. High Rate Infiltration and Dedicated Spray Irrigation – (2 sites – IP and Mercer Mill tracts) 2.540 MG, 88.74 acres of combination infiltration basins and dedicated solid set irrigation. A total of 11 infiltration basins and 14.9 MG of wet weather storage.

3. Golf Course Irrigation – 1.746 MG, 252 acres (2 sites – St James and Winding River) 16 MG of storage at the combined sites. The WWTF has a huge system dispersed across five different disposal sites, a total of approximately 840 acres. The reclaimed water infrastructure ranges from 2-inch to 24-inch “purple pipe” and pumps capable of up to 3,300 gpm. There are 17 different pumps associated with conveying the reclaimed water throughout the system and
over 25 miles of dedicated reclaimed water discharge piping. Geographically, it takes over two hours to go site to site for daily checks – excluding the golf course options.

Personnel

The facility operates with nine full-time employees and four proportional employees – maintenance mechanics/ lab personnel shared with other facilities within the county. The staff is proud of the fact that they have six full-time day and shift operations staff, four Grade IV WW operator certifications, one Grade II operator license and one trainee. Several staff members also have spray irrigation and land application certifications. In addition, the maintenance staff also hold spray irrigation and maintenance mechanic certifications. This is made possible through the Career Ladder program, which encourages staff development.

Awards

Safety

The safety of the employees is something the staff takes very seriously. They are continually looking for innovative ideas and ways to improve on the overall safety program. They are very proud of the fact that they have not had a lost-time accident in the history of this facility. The weekly tailgate meetings cover a broad spectrum of safety-related topics; the monthly meetings further enforce with a safety topic. The staff has quarterly department-wide safety meetings that encourage participation in

Contact Information

Plant staff

Aeration basin

Fine screen

Headworks

Plan effluent

Solids handling facility

Originally published in the Spring 2017 issue of NC Currents magazine.

General

Located in the central part of the state, just south of the NC/VA state line, the City of Eden is the largest city in Rockingham County. The City of Eden was incorporated in 1967 when three other towns merged. It has the nickname “Land of Two Rivers” because of the Smith and Dan Rivers flowing together on the south side of Eden. In 2011 the city received one of the All-America City Awards.

The City of Eden currently operates one WWTP that services a population of 15,488. It was put into operation in 1967 and is publicly owned. The WWTP currently employs a total of nine staff, consisting of 13 operations and maintenance staff and one laboratory staff, and has an annual operating cost of approximately $1.5 million.

The plant’s effluent discharges into the Dan River, part of the Roanoke River Basin. After leaving the WWTP, the Dan River flows back into Virginia and then eventually to the Kerr Reservoir on the Roanoke River. The WWTP has a design flow of 13.5 mgd and operates with an average daily flow of 4.5 mgd. Peak flow is 14 mgd.

Basic Treatment Processes

The city has 20 pump stations that pump all wastewater to the plant. Currently, the Mebane Bridge plant operates at one-third its capacity and is using half of the plant for treatment, with the other half ready for backup or peak flows. The plant has mechanical bar screens to remove larger inert material and a grit removal system following the bar screens. A fine screen has been added after the grit removal system to further remove any material that is missed by prior treatment systems. Extended aeration using activated sludge is the next process to reduce and remove biochemical oxygen demand. It consists of 12 brush aerators per basin and three SolarBees® for mixing, allowing the operators to turn off part of the aerators during peak power demand. The sludge is separated from treated water by circular clarifiers. Collected sludge or biosolids are wasted to the aerobic digester or returned to the aeration system. The biosolids from the digester are then dewatered and land applied on permitted sites. Treated water to the effluent leaves the clarifiers and is disinfected with chlorine and then dechlorinated. The treated effluent is then returned to the Dan River, meeting all state permit discharge requirements.

The last plant expansion was in 1992. There are no plans for expansion, but the staff is planning to redo the solids handling section of the plant and do away with the digester.

The plant has limited automation through SCADA. Alarms for high water near the bar screens are monitored along with low DO in the basins. Aerators can be controlled on and off in the aeration basins. Influent and effluent flow can be monitored along with the equipment run time.

The primary sources of influent are domestic, due to the decline of textile manufacturing in the area. There is one textile plant left, along with a chemical recycling plant, a plastic recycling plant, and a small metal finishing boiler plant.

Solids Treatment

Currently, the plant has one digester that handles all of the wasted sludge. It is original to the plant and was not part of the 1992 upgrade. The plan is to eliminate this basin and run all of the wasted sludge through a Clean B system before being dewatered.

The biosolids management program includes a 2-meter belt filter press (BFP) that dewaters all of the sludge. It is then stored onsite on a covered storage pad until it can be land applied on permitted fields in the area. All dewatering and land application is handled by Synagro. The entire system was built through a design-build-operate contract.

Disinfection

The plant’s disinfection system utilizes chlorine gas for disinfection. The system includes two 500 pounds per day (PPD) flow proportional gas feeders, one 500-PPD manual gas feeder and three baffled chlorine contact basins. Before being released to the river, the effluent is dechlorinated with sodium bisulfite. A flash mixing chamber with a turbine-type mixer provides the required mixing.

The operations personnel have a very active risk management and process safety plan to monitor the safety issues associated with having gas chlorine onsite.

Challenges and Unique Features

The plant operations team faced a difficult problem when it lost its largest industry, one that contributed 3.6 mgd, which was half of the plant’s flow. Operations had to quickly figure out how to adjust treatment in a plant with very little flexibility. They were able to use this adjustment period to get the basins cleaned out and the clarifiers rehabbed while there were still funds available. They have still had to make adjustments during low flows, but they are able to handle high peak flows from rain events with no issues.

 One of the most unique or interesting things about the facility is the SolarBee® mixers. They are the only ones in the state that are used for mixing assistance in an aeration basin. A number of trials were performed to address this issue, and it has proven to be a huge savings to the electrical budget by providing flexibility to turn aerators off for several hours every day.

Personnel

The WWTP offers personnel development programs that encourage cross training for all employees in any area of interest.

The plant personnel includes five Grade IV, one Grade III, two Grade II, and one Grade I operators. In addition to this, three have a pretreatment license and three have certifications in lab analysis, one in maintenance tech, and one in land application. As well, the superintendent has B Surface, B Distribution, and Collections II certifications. One member of the staff is cross-trained at the water plant and one is working on his backflow/cross connection and collections certifications.

The plant’s safety and health program personnel have been Safety and Health Achievement Recognition Program (SHARP) certified through the NC Occupational Safety and Health Administration (OSHA) for the past five years. Operators rotate terms on the City’s Safety Committee and assist with updating the Safety Manual. They are also active in keeping process safety manuals up to date.

Awards

George W. Burke Safety Award

Melinda Ward, William D. Hatfield Award

Contact Information

Melinda Ward, Wastewater Plant Superintendent Phone: 336-627-1009 E-mail: mward@edennc.us

General

The Kerr Lake Regional Water System (KLRWS) is located in the City of Henderson, NC, north of the Triangle on Kerr Lake and is accessible by I-85. The system provides water to approximately 50,000 customers. The City of Henderson is the main shareholder in a partnership of three, which also includes the City of Oxford and Warren County. Together, these providers supply water to Franklin County, the Village of Kittrell, the Town of Stovall, Vance County, and parts of Granville County. The Kerr Lake Regional Water Treatment Plant (WTP) is a 10-mgd facility with capacity for 15 mgd; daily average is around 7.0 mgd. The water source for the WTP is Kerr Lake.

WTP Background History

The concept of a regional water system came about around 1973 to 1975 when the Miller Brewing Company was interested in relocating to the City of Henderson. Because the Kerr Lake Regional WTP was not producing enough water, however, Miller Brewing Company decided to relocate to Eden, NC, resulting in a significant economic loss for the city and its surrounding communities. As a result, the City of Henderson, City of Oxford, and Warren County – with the collaboration of the city manager of Henderson (Melvon Holmes), the city manager of Oxford (H. T. Ragland), and the president of the Soul City Company (Floyd B. McKissick Sr.) – decided action needed to be taken in order to secure more water for their communities and attract other businesses to the region. They joined forces and set out to procure funding.

At the time, McKissick Sr. was developing Soul City, NC, which was one of the new cities across the country that were being funded by the federal government. These new communities were built in areas that had little resources to help them obtain water, roads, housing, and other basic human needs. McKissick Sr.’s first request for funding from the federal government was turned down, but he didn’t let that stop him. He went to Washington, DC, and convinced Nelson Rockefeller to get the funding he needed. After these efforts, it took several years to develop a plan, and L. E. Wooten of Raleigh was eventually hired as the consulting firm to help construct the Kerr Lake Regional WTP. The WTP was completed in 1974 and is still owned today by the City of Henderson, the City of Oxford, and Warren County.

Treatment

The Kerr Lake Regional WTP is a conventional treatment system, consisting of coagulation, flocculation, sedimentation, and filtration. Aluminum sulfate is the primary coagulant with polymer used as an aid; liquid hypochlorite is used for disinfection. In 1996, the WTP performed filter rehabilitation on all four of its filters and conducted a capacity study. As a result, it was approved as the first WTP in the state to have the ability to use a high-rate filtration in order to increase its capacity from 10 mgd to 15 mgd, without the need for a physical upgrade.

Solids Management

The basins in the sedimentation process have a “spyder” system that draws alum sludge off the bottom of the basins and sends it to two thickeners and a square cement holding clarifier. Supernatant is then decanted back to the lake, with the solids being land applied and handled by Granville Farms.

Operations

The Kerr Lake Regional WTP can be operated almost completely by its SCADA system. Most pumps and valves can be controlled from the control center in the main building. With a mostly consistent raw water source and low raw-water turbidity, operational challenges are minimized. When fully staffed, there are 12 available operators, and any operational challenges are handled promptly, effectively, and efficiently.

Staff

When staffed to capacity, there are 13 fulltime employees that work at the Kerr Lake Regional WTP. There is one director/ORC and one chief operator/ back-up ORC. There are seven operators, two maintenance personnel, one lab analyst, and one administrative secretary.

Staff Development

Table 1 on the previous page shows the certification requirements for all employees at the Kerr Lake Regional WTP. In addition, staff members are highly encouraged to go beyond requirements and attain the highest level of certification possible, where appropriate. Any available classes that employees wish to attend are always considered, taking into account schedules, time, and available funds. Cross-training is also highly encouraged. In order to accommodate a WTP that needs to be operated for 24 hours a day and seven days a week, the Kerr Lake Regional WTP has two shifts per day. Each operator has a three-day work week, with two 14-hour days and one 12-hour day. The director, chief operator, chemist, maintenance staff, and administrative secretary all work eight hours, Monday through Friday.

Health and Safety

The KLRWS takes the health and safety concern of its employees very seriously. Working around bulk chemicals on a daily basis and smaller chemical amounts in the Chemical feed Lab Filter consoles

Awards

The Kerr Lake Regional Water System has received numerous awards and achievements, as listed below. • NC AWWA-WEA Best-tasting Water º 1st place: 2000, 2001, 2002 (First and only WTP to win three times in a row) º 2nd place: 1989, 1994 • NC Rural Water Association Best-tasting Water º 1st place: 2013 º 2nd place: 2014 º 3rd place: 2011 • NC Rural Water Association Spirit Award 2003 • NC Rural Water Association – Certificate of Achievement Source Water Protection (First WTP in the state to complete) • NC’s Area Wide Optimization Program º 2004-2005 and 2007-2015

Future Plans

A major expansion of the Kerr Lake Regional WTP to double its capacity size from 10 mgd to 20 mgd is in the works for Fiscal Year 2018-2020.

Contact Information

Christy Lipscomb, Director/ORC
Email: clipscomb@ci.henderson.nc.us
Phone: 252-438-2141 Fax: 252-438-7866

By Chris Maidene, Treatment Plant Supervisor and John Rutledge, Smart Cover Systems
(NC AWWA-WEA Plant Operations & Maintenance Committee)

General

Located in central NC, the City of Albemarle is the largest city in Stanly County, with a current population of approximately 16,000. The city was incorporated in 1857 and is the county seat. In addition to several manufacturing facilities, Albemarle is only minutes from Morrow Mtn. State Park, which is part of the Uwharrie Mountains.

The City of Albemarle currently operates two Water Treatment Plants. The Tuckertown WTP is located on Highway 49 near the Tuckertown Reservoir bridge and Stanly County line. The second plant is the Highway 52 WTP located on Highway 52 North. The source water for the Highway 52 WTP is the Narrows Reservoir. The drinking water from both of these two plants is blended in the distribution system then sent to the City of Albemarle and Stanly County Utilities. In addition to this, the water is sold wholesale to Concord/Kannapolis and the Pfeiffer/N. Stanly Water Systems.

Planning began in 1983 for the Tuckertown WTP and after construction the plant was put into operation in 1991. The WTP currently employs a total of eight plant personnel with an annual operating budget of approximately $4 million.

The plant treats raw water that is pumped from the Tuckertown Reservoir, which is part of the Yadkin/Pee Dee River Basin. The reservoir is located between Badin Lake & High Rock Lake.

The WTP has a design flow of 6.8 mgd and operates with an average daily flow of 3.2 mgd and a maximum daily flow of 5.5 mgd. The plant was originally designed such that it could be expanded to 30 mgd, but due to the loss of some local industry additional water capacity is not needed at this time.

Process Flow Description

Raw Water Intake and Pump Station

The Raw Water Intake and Pump Station were originally built in 1985 to supply water to the Highway 52 WTP. After the Tuckertown WTP was completed in 1991, the water was sent to the plant and the remainder of the Highway 52 line was converted to a finished water service main. The intake structure includes one intake screen and two vertical turbine pumps rated for 3,500 gpm at 200’. The intake screen includes a backwash and air scour system. The pumps were installed as part of the original 1985 installation. A third pump was added when the new WTP came on line.

Raw Water Reservoir

The Raw Water Reservoir was built to provide water supply to the plant during periods of high turbidity or contamination in the Tuckertown Reservoir. It is an earth construction type with a HDPE liner. The maximum capacity is 42 million gallons at its highest elevation. It includes three floating aerators that are located between the outlets.

Flash Mix Tank and Flocculation

Prior to the Flash Mix Tank, alum is fed into the raw water line. It is mixed in the 16,500-gallon tank using one 5-HP vertical turbine mixer. A raw water sample is sent from here to a raw water turbidimeter and streaming current detector (SCD). The SCD is used to manually adjust the alum feed. Raw water entering the plant flows through a 20-inch Venturi flow meter with an integral butterfly control valve.

Once flow leaves the flash mix tank, it enters a dual train flocculation basin. The basin consists of six cells with each cell having a capacity of 31,500 gallons. The flocculators consist of six vertical turbine slow speed mixers – one each cell, three per train.

Sedimentation Basins and Filters

The Sedimentation Basins consist of four 439,250-gallon conventional style rectangular basins. The flow from the Flocculator Basins enters through a central channel. Each flocculation train can be isolated to flow into any of the sedimentation basins. Sludge removal is accomplished using a vacuum sludge removal system with its primary control panel located next to the main control panel in the operations building.

The Filter Basins include four conventional dual cell filters that are made up of anthracite, sand, gravel and gullet. The flow from the sedimentation basins enters through a central channel allowing flow to be isolated into any of the filters. Each filter has an area of 364 SF and a flow rate of 3.05 gpm/SF and is equipped with rotary surface sweeps and washwater troughs. The pipe gallery instrumentation includes filter effluent turbidimeters and flow meters. Three dual filter consoles are located directly above the pipe gallery on the main floor of the operations building. From each console, manual backwash control can be initiated.

Clearwell and Finished Water Pumps

The 280,000 gallon clearwell is constructed of cast-in-place concrete and includes baffle walls to provide the required cycle threshold value.

There are two 250-HP finished water pumps that are rated at 8.2 mgd. If required, the flow can be trimmed using discharge butterfly valves. Finished water is pumped to the stripping towers to remove VOCs and then pumped into the 4 MG ground storage tank. Finally, the finished water flows into the distribution system.

Chemical Feed and Disinfection System

The chemical feed system consists of fiberglass reinforced plastic (FRP) bulk storage tanks and metering pumps. Bulk storage includes two 10,000-gallon tanks each for alum and caustic, one 6,000-gallon tank each for fluoride and sodium bisulfate and drum storage for polymer and orthophosphate. Disinfection is achieved by a conventional gas chlorination feed system. It consists of two manual chlorine gas vacuum feeders (two standby) rated up to 500 PPD. In the summer the system feeds 2.3 ppm and in the winter it feeds 1.8 ppm. Chloramination was determined to not be an option due to a kidney dialysis center that receives water from the WTP.

Stripping Tower and 4 MG Ground Storage Tank

The Stripping Tower and Ground Storage Reservoir are located on a hill overlooking the plant. The finished water pumps send water from the clearwell to the stripping tower and a portion to the 1 MG backwash tank. The stripping towers consist of two force draft, packed tower aerators for removal of volatile organic compounds (VOC). The towers are 12 feet in diameter and 24 feet in height. They each utilize two 20-HP fans at 23,600 CFM. Post chlorine is fed into the tower outlet piping and then pumped to the 4-MG ground storage tank.

Solids Treatment

Sludge removed from the sedimentation basins are pumped to the sludge tank. The backwash water is collected into two decant basins. Supernate decanted off the decant basins is sent to the lagoon for holding, while sludge from the decant basins goes to the sludge pit. The sludge is removed by a sludge removal company contracted by the city then land-applied to a seven-acre field adjacent to the WTP.

SCADA System

The original WTP was equipped with a large freestanding control panel with chart recorders, meters, indicating lights and a graphic display panel. While the panel still exists in the control room, the primary control functions of the plant have been replaced with a supervisory control and data acquisition (SCADA) system. This system consists of computer monitors, human-machine interface (HMI) software and communication network that allows the operators to view the operations of the plant. The filter backwash system is automated using programmable logic controllers (PLC), but can be placed in manual if necessary.

Laboratory

The laboratory staff performs a variety of analyses at the in-house lab located in the operations facility. Process and finished water are analyzed for total coliform, E. coli bacteria, hardness, iron, and fluoride on a daily basis.

A spectrophotometer is used for many of the analyses, most frequently for iron, fluoride, and chlorine. It is also used for nitrate and copper for the purpose of reservoir management, UV254 absorbance to quantify organic material in process water, and the estimating of total trihalomethanes (THMs) content. A Colilert test is used for bacterial analysis of water sampled at the plant as well as the 15 samples collected each month in the distribution system. All parameters that require testing only quarterly or less frequently are outsourced to an independent lab.

Challenges

One of the biggest challenges for the WTP has been THM and haloacetic acid (HAA) issues. In order to address this issue, it was determined that the chlorine feed rate required adjustment to minimize the THMs and HAAs while still providing the required amount of disinfection and residual to the finished water. In addition to this, prechlorine feed to the head of the plant was eliminated to further minimize THMs.

Unique Process Features

The most remarkable feature of the plant is that it utilizes force draft, packed stripping towers for the treatment of VOCs. Air stripping is accomplished in the packed tower when dissolved molecules are transferred from water into a flowing air stream. The water is pumped to the top of the tower and sprayed uniformly across the packing through a distributor. It flows downward by gravity in a film layer along the packing surfaces. Air is blown into the base of the tower and flows upward, contacting the water. The packing provides a very large surface area for mass transfer of VOCs from the water to the air and out the top of the column. After this process, the water is sent to the ground storage tank and then on to distribution.

Wildlife

The plant sits on 200 acres and has abundant wildlife living on acreage behind the facility. Wildlife such as deer  turkey, osprey, coyotes, barn swallows  and eagles nesting can often be seen. The Tuckertown Reservoir is home to countless fishermen who can be seen anytime day or night near the plant entrance or on the water. It is one of the many beautiful areas that North Carolina has to offer.

For additional information:
Chris Maidene, WTP ORC
PO Box 190
Albemarle, NC 28002-0190
Phone: (704) 986-9656
cmaidene@albemarlenc.gov
www.albemarlenc.gov

Administrative building
South Aeration Basins
North Aeration Basins
Aerobic Digesters
Belt Filter Press
Biological Phosphorus Removal Basins
Deep Bed Sand Filters
SCADA Plant Overview
New UV System Retrofit
GUC Staff: JoEllen Gay - Environmental Compliance Coordinator; Jason Manning - Plant Superintendent; Bryan Bland - Chief of Maintenance; Chris Hill - Operations Coordinator

By Jason Manning, Greenville Utilities Superintendent and Chris Hill, Operations Coordinator
Edited by John Rutledge, Smart Cover Systems (NC AWWA-WEA Plant Operations & Maintenance Committee)

This Plant Spotlight was originally printed in the Summer 2016 issue of NC Currents magazine. 

General

Located in eastern NC, the City of Greenville is the largest city in Pitt County with a current population of approximately 91,000. In addition to 15 major manufacturing facilities, Greenville is home to East Carolina University and a well-respected medical community.

Greenville Utilities, established in 1905, is owned by the citizens of Greenville, but operates under a separate charter issued by the N.C. General Assembly. GUC is a Public Not for Profit Municipal Agency. In addition to water & wastewater services, GUC provides electric & natural gas services to the City of Greenville and 75% of Pitt County. GUC serves a combined total of nearly 150,000 customer connections.

Greenville Utilities currently operates one WWTP that services a population of 91,000 plus which includes Greenville and neighboring Bethel and Grimesland, NC. It was originally put into operation in 1985 with a rating of 10.5 MGD. In 1995, it underwent an upgrade that increased the plant rating to 17.5 MGD. The WWTP currently employees a total of 29 plant and pump station staff.  They consist of 20 O&M, four Laboratory & five administrative personnel. The plant has an annual operating cost of approximately $8 million.

The plant treats both domestic and industrial wastewater from the city and the surrounding community.
The plant influent consists of approximately 90% domestic and 10% industrial wastewater.

The plant’s effluent discharges into the Tar River, a Class C-NSW water in the Tar-Pamlico River Basin. The WWTP has a design flow of 17.5 MGD and operates with an average daily flow of 10.6 MGD. Peak flow is 30 MGD.

The key treatment processes include:

• (2) Bar Screens
• (2) Grit Removal Systems
• (1) Odor Control System
• (5) Aeration Basins with Diffused Air
• (2) Biological Phosphorous Removal Basins
• (5) Secondary Clarifiers
• (7) Tertiary Treatment Deep Bed Sand Filters
• (1) UV Disinfection System- 2 Channel
• (3) Aerobic Digesters
• (2) Belt Filter Presses
• (1) Hauled Waste Receiving Station

The WWTP is permitted for a total flow of 17.5 MGD and operates two liquid treatment processes.
The North Plant was constructed in 1985 and is comprised of three treatment trains and utilizes nitrified recycle to reduce nutrients in the final effluent.
The South Plant was constructed in 1995 and employs two oxy-ditches and biological phosphorous removal cells to attain enhanced biological nutrient removal. The effluent from both plants receives secondary clarification and tertiary treatment with sand filters. The final effluent is UV disinfected prior to discharge to the Tar River.

Both the North & South plants are in “good” overall operating condition due to an active inspection and maintenance program. Current two year ADF average (May 2013-2015) is 10.60 MGD and consumes 61% of available permitted capacity.

Biosolids are dewatered on site and trucked to contracted vendor for composting. Class A compost is the final disposition of all biosolids produced at this facility.

Current and Future Expansion

UV Disinfection Upgrade Project began construction in late 2015 and is scheduled for completion in the spring of 2016. The goal of this project is to install a more reliable and energy efficient disinfection system sized to handle Peak Flows. The current horizontal UV system is being replaced by a two channel UV system that uses modules consisting of vertical UV lamps.  Energy efficiency is achieved by the ability to turn on and off modules of UV lamps to meet the lowest diurnal flows. Reliable disinfection will be increased by this effort.

Air Piping Upgrade Project is currently in the engineering phase. The GUC staff identified issues with compressed air delivery to the South Aeration Basins. An energy efficiency study quantified energy losses in the air piping of over $172k /year. This future project will increase energy efficiency, reduce operational risks and allow staff increased operational control of aeration.

Biosolids/Dewatering Upgrade Project is currently in the engineering phase. The GUC Board approved a Biosolids Project budget to increase the sustainability and operational effectiveness of the biosolids management. The project will also be scoped to include nutrient management of dewatering process side streams.

Electric/SCADA Upgrade was completed in early 2016. The WWTP was recently upgraded with redundant electrical support for all critical equipment. A self-healing fiber ring was installed to support a comprehensive SCADA upgrade for the plant and pump station.

Master Plan for the WWTP was recently completed. This Master Plan projects future demand and the required infrastructure improvements needed to meet forecasted customer demand and predicted asset condition due to age, use and environment. The Master Plan also takes into account regulatory constraints and plots current plant performance against those predicted limits. Where performance gaps are identified – projects are proposed and supported. All aforementioned projects were accurately predicted in the Master Plan. Future projects (within 5-year window), such as additional clarification on the South Plant, will be focused on increasing treatment and permitted capacity.

SCADA System

The facility is fully automated using the latest SCADA technology and equipment, but is easily operated by hand if the need arises. The recently updated servers and software were installed to improve operation and efficiency. In addition, operations, maintenance, and lab tasks are scheduled and logged using an Oracle based work order management system. This system is easily accessible by desktop and by iPad.

Solids Treatment

Waste Activated Sludge (WAS) is stored in three aerobic digesters. Discharge from the digesters is sent to two Andritz belt filter presses for dewatering. Currently these units produce approximately 2,000 dry tons per year at an average of 17.5%.

Biosolids Management

All dewatered biosolids are sent to McGill Environmental for treatment and final disposal as a raw product for compost. The WWTP staff samples the biosolids quarterly and provides analysis results to McGill Environmental. McGill Environmental is responsible for all Class A Biosolids regulatory reporting.

Disinfection

Construction began in late 2015 to remove the existing energy intensive UV system and replace it with one that is more energy efficient. The new replacement is an Ozonia (Suez) UV system that utilizes vertical UV lamp modules and has met all expectations.

Laboratory & Pretreatment

The laboratory is staffed by three laboratory technicians who have several years of experience.  They are certified for 27 parameters with the State.  The lab performs sampling at various locations on the plant for analysis and is involved with many projects at the plant.  GUC currently regulates six Significant Industrial Users and four non-Significant Industrial Users as part of the pretreatment program.  The pretreatment program is staffed by one Industrial Pretreatment Specialist who samples all industrial locations and judges compliance once lab staff has completed the analysis.  The pretreatment/lab section of GUC’s WWTP functions paperless for the most part. The staff is seeking certification in WW Operations and in Pretreatment.  As regulations evolve, the staff adjusts accordingly.  

Treatment Limits

The wastewater effluent is permitted for the following limits:

• BOD limit 8.0 mg/l (summer): 15.0 mg/l (winter)
• NH3 limit 4.1 mg/l (summer): 8.2 mg/l (winter)
• Annually allocated 249,576 lbs of Total Nitrogen and 45,103 lbs of Total Phosphorus through the Tar Pamlico Basin Association
  
  

Personnel Development Programs

Greenville Utilities offers many internal training and development opportunities for all of its employees. These include customer service, self-leadership, situational frontline leadership, career advancement, safety, diversity, interviewing, and many more.

Certifications

The WWTP is a Grade 4 facility. Operations, maintenance, lab and administrative staff are encouraged to achieve the highest level of certification in wastewater, collections, maintenance, lab analysis, leadership, and other related areas.

Among the WWTP operations and laboratory staff, there are certified Wastewater Treatment Operators, certified Land Application Operators, certified Spray Irrigation Operators, certified Wastewater Collection System Operators, certified Lab Analysts, a certified Pretreatment Specialist, a licensed Public Pesticide Operator, a certified Maintenance Technologist, and a licensed Plumbing, Heating and Fire Sprinkler Contractor.

Among the WWTP maintenance staff, there are certified Maintenance Technologists, an ISA Certified Control Systems Technicians, a licensed Public Pesticide Operator, a State Board of Refrigeration Examiners Universal Technician, an EPA R410a certified Technician, certified Collection Systems Operators, and certified Wastewater Operators.

Personnel Management

Greenville Utilities offer flexible scheduling for both laboratory and maintenance personnel. Flexible scheduling has allowed the individual to choose a schedule which is best for their family. For example, Lab staff may choose to work four 10 hour days- this provides a benefit for the employee, the employee’s family and Greenville Utilities with increased hours of laboratory support. The managerial approach to personnel is to ensure all individuals know their worth to the plant and are provided opportunities to add value to the operation.

Safety and Health Program

Highlights of the program include Lighthouse Observation; American Heart Association First Aid, CPR and AED training; and Smith Driving System. Lighthouse is a peer observation program that reinforces positive work habits instead of punishing bad work habits. Smith Driving System is the leading provider of collision avoidance driver training and all GUC employees must complete this program every three years.

Awards

• NC Department of Labor Certificate of Safety Achievement
• 2008 WEF George W. Burke, Jr. Facility Safety Award
• 2001 EPA Operations & Maintenance Excellence Award
• 1999 EPA Beneficial Use of Biosolids Award
• 1998 EPA Biosolids Beneficial Use (Large Operating Projects) – Honorable Mention
  
  

Challenges

Some of the challenges that the operations staff have faced is implementation of Oracle Work and Asset Management fully integrated with GUC’s Financial Accounting System – Oracle’s EBS, ESRI GIS and SCADA.

Historically, the WWTP and Pump Station Staff have struggled with planning, executing and documenting work performed. Operation and maintenance of critical assets relied on word of mouth or hand written notes. GUC did not have an enterprise system in place to know what assets they had, what their value was and how they used and maintained them. In the span of less than a year, Operations and Maintenance Staff successfully transitioned to a digital – mobile mode of performing and documenting work. Plant and Pump Station Staff utilize iPads to issue work requests, record operational readings, record work effort, inspection information and access SCADA information remotely.

GUC is evolving into an asset management mindset – this is a cultural shift for employees and management alike. GUC has been blessed with visionary leadership that empowers the employees with technology and tools to be more efficient and effective for the ratepayers.

Summary

The plant is an exceptionally performing facility that is 100% biological. The staff has eliminated chemical additions in the process. The final effluent flows to the Tar River via a channel that is teeming with aquatic life that supports wildlife living on acreage behind the facility, which belongs to Greenville Utilities Commission. Wildlife such as deer, turkey, and eagles nesting can often be seen. The facility is a visually beautiful treatment plant with various trees and vegetation throughout the property. The reclaimed water from the plant is used for irrigation to enhance this landscape. The plant staff takes much pride in the operation, maintenance and appearance of the facility.

For additional information please contact

Jason Manning, WWTP Superintendent (manninmj@guc.com)
Chris Hill, Operations Coordinator (chill@guc.com)
240 Aqua Lane
Greenville, NC 27834
Phone: (252) 551-3304

General

Located in the ‘Heart of North Carolina’, the City of Asheboro is the largest city in Randolph County.  Its beginnings date back to the 1780’s and it now has a population of approximately 25,000. In addition to its industries, Asheboro has the distinction of being home to one of the world's largest natural habitat zoos with over one thousand animals.

The City of Asheboro currently operates one WWTP that is located north of the city. It was originally put into operation in 1962 and underwent expansions in 1975, 1986 and 1996. It currently employs 21 O&M, 5 Laboratory & 4 administrative personnel. The plant has an annual operating cost of approximately $2.4 million.

The plant treats both residential and industrial wastewater from the city and the surrounding community.

Since 2005 many of the major industrial users have shut down or moved. During this time, the plant influent went from 70% industrial to 70% domestic. This decline of industry resulted in a loss of 3 MGD in daily average flow. There are currently 13 significant industrial users.

The plant’s effluent discharges into Hasketts Creek and has a design flow of 9 MGD. Currently the plant operates with an average daily flow of 3.0 MGD. During significant rainfall events, the plant has experienced a peak flow of 24 MGD.

Treatment Processes

The wastewater effluent is permitted for the following limits:

• BOD limit 5mg/l : 10mg/l
• NH3 limit 2mg/l : 4mg/l
• Permitted to “monitor only” for total N and Phosphorus

The basic treatment processes include:

Preliminary Treatment

Wastewater enters the Asheboro Treatment Plant through two main collection lines.  The 36-inch sewer line flows into the plant by gravity and the 24-inch gravity sewer is pumped through the spiral lift station into the plant.  The two flows combine at Junction Box #1.  

Influent from Junction Box #1 sewer system enters the preliminary treatment structure through a 42-inch ductile iron pipe.  The wastewater passes through an automatically cleaned bar screen then a 15 MG Vortex Pitas Grit System.  Both the screenings and grit are then removed by a single belt conveyor.  Once this occurs, the wastewater flows by gravity through a parshall flume (20 MGD rated) where the influent flow is measured by an ultrasonic flow meter.

The wastewater from the preliminary treatment then flows into the primary splitter box, where the flow is split, going to a 3 MGD rated Circular Primary Clarifier, and six Rectangular Primary Clarifiers rated at 1 MGD each. The settled wastewater then flows into the trickling filter recirculation pump station.

Primary Treatment

Settled primary sludge is collected by scrapper collection equipment into a sludge hopper located at the inlet end of the rectangular tanks and the center of the circular tank.

Primary sludge is pumped out of the circular tank automatically set by timers, and removed from the rectangular tanks automatically by air, which is controlled by a PLC.

Scum is removed from the surface of all tanks, removal pipe on rectangular tank manually, and by scrapper into a hopper on the circular tank.

Secondary Treatment

Secondary biological treatment consists of a recirculation pump station, trickling filters, recirculation junction box and secondary clarifiers.  The primary settling tank effluent flows into the recirculation pump station.  The recirculation pump station consists of four centrifugal pumps rated at 6 MGD.  These pumps are utilized to pump the primary clarifier effluent and the recirculated trickling filter effluent to the trickling filters.

There are three (3) trickling filters, which are operated in parallel.  Rotating distributor arms are used to distribute the flow evenly over the surface of the filters.  As the flow trickles through the stone media, the biological growth on the stone surface absorbs the organic material in the wastewater, thus reducing the BOD in the wastewater.  The filter drainage is collected in an under drain and flows to the recirculation junction box and filter recirculation valve vault.  The recirculated flow goes to the recirculation pumping station while the remainder of the flow discharges into the secondary clarifiers.

There are two trickling filter recirculation patterns, one with trickling filter effluent back to filter influent with primary effluent and one with secondary effluent back to filter influent with primary effluent.

There are four secondary clarifiers, which are utilized to settle the trickling filter humus.  In general, 0.3 to 0.5 pounds of humus are produced for every pound of BOD removal in the trickling filter.  The sludge is removed by air on set timers.  Scum is removed to the scum pipe by the returning collector flights, and then rotating the scum pipe.  Total volume of all four tanks is 108,066 cubic feet.  The total linear footage of the weir is 816.

Tertiary Nitrification Treatment

Secondary clarifier effluent flows to two single-stage nitrification activated sludge trains.  The nitrification trains consist of a circular aeration tank and a circular center feed, peripheral take-off final clarifier.  Return sludge from the final clarifiers’ mixes with the secondary clarifier effluent in the wet well of the nitrification pump station and is pumped to the nitrification splitter box through a 30-inch DIP.  The splitter evenly divides flow into the two nitrification basins with subsequent flow to the clarifier splitter box through a 36-inch DIP.

The nitrification pump station consists of four variable speed pumps with 7 MGD capacity.  

Aeration and mixing in the nitrification basins are accomplished by the Schreiber process, whereby air is introduced at the bottom of the aeration tank by a series of diffusers, which are suspended from a rotating arm.  “Counter-current aeration” is achieved by providing the air through the rotating diffusers.  In this manner, the manufacturer claims that the air is in contact with the wastewater longer and, consequently, more efficient oxygen transfer is achieved.

The Asheboro activated sludge system is operated under conditions to foster growth of specific types of bacteria, which will convert ammonia-nitrogen (NH4-N) to nitrate-nitrogen (N03-N).  Nitrification is needed at the WTF because the conversion of NH4-N to N03-N requires a lot of oxygen, which would be taken from Haskett’s Creek if bacteria in the creek were to perform the nitrification.

The two nitrification aeration basins have a capacity of 2 MG each, with air provided by three variable speed centrifugal blowers, one up to 1,200 cfm, and two up to 5,000 cfm each, and six positive displacement blowers 760 cfm each.  Mixed liquor exits each aeration basin through a mixing chamber.  The mixing chamber is provided to allow chemical addition, if required.

Calcium Hydroxide may be added to the nitrification splitter box, if needed, due to alkalinity and pH depletion by nitrification reactions.  

The mixed liquor then flows to the clarifier splitter box.  The clarifier splitter box splits the flow to the three clarifiers.  Polymer may be added to the discharge of the clarifier splitter box to assist in precipitation in the clarifier, if needed.  The discharge from the splitter box then flows to the center inlet well of the clarifiers.  Settled sludge is continuously removed from the clarifier bottom through hydraulic suction-type collectors to the center sludge well.  From there the sludge flows by gravity to the return sludge valve vault.  The sludge then can be recirculated to the nitrification pump station through the return sludge valve vault.  Sludge is wasted through a 6-inch gravity flow line from the return sludge valve vault to the sludge conditioning building.  The waste sludge is metered utilizing an ultrasonic flow meter.  An ultrasonic flow meter is installed in each return sludge line within the return sludge valve vault.  Return sludge flow rates are adjusted by hydraulically activated plug valves within the return sludge valve vault. Skimmers remove floating solids from the surface of the water in the clarifiers.  Skimmings flow by gravity from a common sump for all clarifiers to the secondary clarifiers.  The three final clarifiers have a total volume of 211,000 cubic feet with a total of 754 weir linear feet.  

Tertiary Sand Filters

The final clarifier effluent then flows by gravity to the tertiary sand filters.  The Parkson Dynasand Filter provides a unique filtration system since it continuously cleans the sand bed while filtering liquid suspensions to the designed effluent quality.  Feed water is passed upward through the sand bed, exiting from the top of the filters as clean water.  At the same time, sand is continuously removed from the bottom, cleaned and returned to the top.  A small portion of the filtered water is used to wash the sand and leaves the filter as reject water flowing into a wet well where it is pumped to the primary splitter box.  The feed is introduced into the filter through the feed pipe.  The feed then passes down through the feed pipe to the distribution radials where it is introduced into the sand bed.  The distribution radials serve to distribute the feed water flow evenly across the sand bed.  From there, feed water passes upwards through the sand bed, being cleaned in the process.  The clean water (filtrate) passes over the filtrate weir at the top and leaves the unit.  The unit consists of four units of eight cells each with a maximum filtration rate of 8 gallons per minute/square foot. The effluent from the sand filters flows by gravity to the chlorine contact chamber where disinfection takes place.

Innovative BNR Process

In 2011, the plant personnel began exploring methods to perform BNR with the existing equipment.  They found that the process didn’t have enough BOD to denitrify. To address this issue, it was decided to form a partnership with one of the local industries, MOM brand Cereals. In the cereal manufacturing process, high strength sugar water is produced. So in order to improve the BNR process, the WTF now trucks in this sugar water and feeds this carbon source during the denitrification process.  This enables the plant to nitrify and denitrify in the same tank by cycling air on and off every 2 hrs.  Total N then dropped from a monthly average of 20 mg/l to 5 mg/l, with the lowest being 1.87 mg/l.  Total P then dropped from a monthly average of 1.0 mg/l to .07 mg/l.
To accomplish this process modification, the plant purchased a 12,000 gallon tank, 2 tanker trailers, feed pump, coriolis flow meter, nitrate sensor, and an ammonium sensor. In addition to this, some minor modifications were made to the existing SCADA system.

Solids Process & Handling

The solids treatment process consists of a Dissolved Air Flotation (DAF) system to thicken the sludge.

Once it is thickened, the sludge is pumped to anaerobic digesters (Thermophylic). After digestion, it is then dewatered utilizing two-1.5 meter belt presses. The filtrate from the presses can exceed 400 mg/l NH3.

The biosolids management program consists of land application using a private contractor.

SCADA

The plant automation system consists of a central SCADA system that controls and monitors the process equipment, instrumentation, valve actuators, motors, pump VFD’s, etc. The aeration system is controlled by blowers that receive an input signal from the dissolved oxygen probes.

Disinfection

During normal operating procedures, Sodium Hypochlorite (chlorination) is fed to the weirs of the three final clarifiers for algae control and added contact time.  It is also fed to the trickling filter influent for control of filter flies (Phychoda), the sand filter influent and then finally to the chlorine contact chamber. In order to meet EPA discharge limits dechlorination is required. This is accomplished when Sodium Biosulfite is fed at the end of the chlorine contact chamber. Once the effluent leaves the contact chamber it flows to the Cascade Aeration system where it is reaerated before discharging into Haskett’s Creek. The chlorine safety record at the plant has been excellent.

Laboratory

The Water Quality Department operates a certified laboratory at the Wastewater Treatment Plant. The laboratory is administered by a Water Quality Manager, Assistant Water Quality Manager, Chemist, Biologist and a Laboratory Technician. All employees are cross trained to perform multiple physical, chemical and biological analyses of water and wastewater parameters for plant operations, industrial survey and state and federal authorities. All analysts hold a degree in biology, chemistry or environmental sciences.  They are certified in "Bacteriological Methods in the Analysis of Drinking Water", "Process Control Chemistry" and as "Class IV through Class II Wastewater Laboratory Analyst."

The Water Quality Department is certified to perform all testing parameters for the NPDES Wastewater Treatment Plant permit, as well as, Monthly Operating Report for the Water Treatment Plant, except for a few quarterly special testing parameters. The Water Quality Department collects and analyzes more than 67,000 analyses per year.

Awards

• 2010 AWWA NC Central Region O&M award winner
• 2010 (John Stake) & 2013 (Chris Schadt) NC Operator of the year award winners
• 'Treatment Plant Operator’ (TPO) magazine article in the November 2011 issue

Future Plant Goals

• Lift Station Flow Meters for I&I
• More accurate control of Aeration Basins
• Thermophylic Digestion
• Class “A” biosolids
• Feed grease, fats, and oils and excess sugar water directly to digester. 
• Increase methane production
• Use methane to fuel generator, which will supply power for entire plant.
• Zero carbon footprint
• Optimize the plant further with additional sensors and instrumentation for monitoring and control
• Plant permit renewal in 2016

Aeration building.

Dissolved air flotation system

Digester

Headworks

Lab

SCADA

The Plant Spotlight is designed to give NC AWWA-WEA Members a comprehensive view of your treatment plant, so here’s your chance to brag about the features and approaches that make your plant exceptional.

Download and complete this questionnaire with as much detail as possible, but note that all questions may not need to be completed to give a good overview of your particular facility.  Remember to include quality digital photos of your facility that focus on specific equipment or processes.  (Digital images should have a resolution of at least 300 dpi. Images from a 4-megapixel camera set at its best setting work well).  Be sure to include captions and photo credit as appropriate.  Please contact the Plant Operations & Maintenance Committee or your plant engineering consultant, if you need assistance completing this form.