When the 3.85 mgd Coatesville (Pa.) Regional Wastewater Treatment Plant needed to increase capacity and meet more stringent permit limits, owner Pennsylvania American Water built a $55 million 7 mgd treatment plant with the latest technology.

The long construction time challenged the operators, as the plant had to be built in the same footprint as the old one. “We had to construct the plant in phases, adding new pieces of equipment from May 2008 to June 2009,” says company engineer and project manager Gerald DeBalko. “From June to July 2009, we had pieces of the old and new plants running at the same time. In August, we started demolishing the old plant as part of the final phase that continued through March 2010.”

The plant, on 14.7 acres within the 200-year-old ArcelorMittal Steel property, is landlocked by the active steel mill and the west branch of Brandywine Creek. The city had purchased 6.7 acres from Lukens Steel in 1931, and in November 2007, Pennsylvania American Water bought eight more acres for the expansion. Yet, even with the extra real estate, much of the new equipment had to fit on the original acreage.

“We were literally running two processes at the same time,” says Richard (Rich) Lutz, production supervisor. “We had to put in piping so we could have half the incoming wastewater going to the old plant and the other half to the new plant.”

Challenges for the operators included working around an active construction site, collecting samples and maintaining equipment for both the old and new processes, and learning the new equipment and controls while keeping the old equipment working.

“Sampling was a bit of a challenge, but we continued to test daily for process control and twice a week for the permit, and we continued to meet all our limits,” says Lutz.

 

Aging plant

Building the new plant was the only way around a worsening situation. “The old plant was barely meeting its limits and would not have met the new permit requirements for phosphorus, nitrogen and copper,” says DeBalko. “In 2006, we were adding 400 to 500 houses a year, and the old plant would not have been able to meet this growth.”

Even more serious were the maintenance issues with the old plant. “We were always worried about the coat hangers and duct tape” breaking at the old plant, says DeBalko. Lutz adds, “Since the old plant was built in 1932, with an upgrade in 1962 and 1988, we found it difficult to obtain parts. We often had to have parts made because they were no longer manufactured or kept in stock by suppliers. And if we couldn’t get parts, we had to do whatever it took to make it work.”

Lutz credits the operators with keeping the old plant working as well as it did: The team collectively had plenty of experience with the primary clarifiers, trickling filters, aeration tanks, final clarification and UV disinfection.

 

In with the new

Started up in March 2010, the new secondary treatment plant includes:

• Three screw pumps (Lakeside)

• Automatic bar screen (Headworks)

• Eutek grit removal system (Hydro International)

• Two anaerobic selection tanks and oxidation ditch (Lakeside)

• Enviroquip SymBio control process (Ovivo)

• Three final clarifiers (Envirodyne)

• Eight CenTROL tertiary filters (Siemens)

• UV disinfection system (Trojan)

• Aerobic sludge digestion followed by gravity belt thickener (Ashbrook) and centrifuges (GEA Westfalia)

A SCADA system (integrator Allied Control Services) allows operators to monitor plant operations, including chemical feed systems, from a central location. Odor control is enhanced with the new system, which eliminated the primary settling tanks.

“Before we decided what equipment to purchase, we explored the different processes that we felt would meet our goals,” says Lutz. “Then we visited several treatment facilities to see the various manufacturers’ products and discuss their operation with the operators.”

The team was able to salvage some of the old equipment. The primary and final clarifiers are now used as mud wells for the tertiary filters. The old aeration tanks were converted to aerobic digesters, and the alum storage tank remains in use, as does the old UV system (a second one was added). The old sludge handling building was expanded for the gravity belt thickener and centrifuges, and the garage is now used for storage and a maintenance workshop.

The plant serves 6,200 direct customers and four bulk wastewater customers in Coatesville and 10 surrounding boroughs and townships. The plant team oversees 79 miles of sewer main and 16 lift stations. Materials used to build the new plant included 20,050 cubic yards of concrete, 2,050 tons of rebar, and 15,750 linear feet of pipe.

The new facility is impressive, and it helps the operators do their work effectively. For one thing, the new plant is better able to handle I&I. “With the old plant, we experienced high flows from rain,” says Lutz. “Now, we have new and modern equipment to handle I&I flows from rainstorms, and we also relocated a large section of sewer main that ran along the stream bed.”

 

Learning curve

The new plant presented challenges to operators used to older technology and a completely manual process. “We went from a very manual plant to an automated facility, and there were many more pieces of equipment than we had before,” says DeBalko. “The old plant was very simple.”

As new equipment was installed, the equipment contractor trained the operators during startup. The manufacturers’ representatives also helped with the training by reviewing the operation manuals during classroom sessions, conducting hands-on equipment training and providing training videos.

But, it wasn’t easy to learn an entirely new, automated process. “Every piece of equipment, from the belt press to centrifuge to SCADA, was difficult,” says DeBalko. “Most operators had never used computerized equipment with a user interface.”

Adds Lutz, “Training in the wastewater field is a day-by-day process, as needed. A short training by the manufacturer is great, but it doesn’t take the place of hands-on experience with equipment. Our operators quickly learned the basic operations, but we are constantly learning about the new process and becoming more comfortable with it.”

 

Always adjusting

They continually adjust the new process to obtain the best phosphorus and nitrogen removal in the oxidation ditch and effective dissolved oxygen and mixing in the aerobic digesters. They also program the set points to meet seasonal requirements.

After the new plant started up, operators had to fine-tune the equipment to keep alarms from sounding. “There were so many sensors and pieces of equipment with alarms, and sometimes we would get false alarms,” says DeBalko. “The manufacturers would have to come out and get rid of the bugs.”

Says Lutz, “If there’s a power failure, the alarms go off, and if a piece of equipment goes down, the alarms go off. There is backup equipment, so if a pump goes down another one will come on, but an alarm still needs to be investigated.” All pieces of equipment have a backup, and SCADA automatically rotates the equipment weekly to keep it in top shape.

Operators take ongoing operations and safety training, and attend outside workshops if needed. Training includes day-to-day operations, arc flash protection training, OSHA 10-hour safety training, confined-space training, fire drills, emergency action planning, fire extinguisher training, defensive driving, chlorine safety, first aid/CPR, forklift training, drug and alcohol training, and security training for water and wastewater systems.

 

What’s next?

The plant is running at 3.5 mgd on average, and growth has been flat. “In the past, we had 400 to 500 new connections a year, but that has dropped and some factories have closed,” says Lutz. “Growth has not increased as much as was projected, but when it does, we will be prepared.”

The plant is sized to handle growth 10 years from now based on projections from the municipalities. The plant is also optimized to minimize power use. “The oxidation ditch has more controls that use power than the trickling filter did, but the SymBio control process reduces power by minimizing the amount of air in the aeration basin, and maximizes the effectiveness of the nutrient removal process,” notes DeBalko.

A new biosolids processing facility, started up in August 2011, allows the beneficial use of the material for land application in place of landfilling. That means environmental benefits and cost savings.

“Right now, we’re not sure how much we will land-apply, but it could be 70 to 80 percent, depending on business and weather conditions,” says DeBalko. Some of the biosolids are being applied to a coal mine reclamation site, and the plant has hired a contractor to find out which farms would want biosolids.

As part of the permit, plant staff will be required to visit farms that use the biosolids to make sure regulations are followed. “Since I raise fish, I have a big interest in the environment,” says Lutz. “As president of the Brandywine Trout & Conservation Club, and as someone who operates two trout nurseries, I am very proud that the wastewater plant is helping to improve the local environment.”

 

Educating others

Municipalities served by the Coatesville plant welcomed the new facility. “The old plant was limiting new growth and development,” says DeBalko. “We have given them tours of the new plant, and after comparing it with the old plant, they were very impressed.”

Brandywine Valley Association members have toured the plant, as have middle school students. “We bring students through and explain the impact on the environment,” says Lutz. The plant staff also invites representatives from municipalities outside the region to visit and see the technology. “We like to help other plants the way they helped us when we were touring facilities and looking at different technologies,” Lutz says.