Becoming a Good Neighbor

How can a wastewater treatment plant become a good neighbor in the community it serves?

Four years ago, the town of Clarksville, Ind., and American Water Operations and Maintenance answered that question.

The answer defined some key goals for their new partnership—to work collaboratively to reduce odors and overflows, improve plant safety and ensure a sound infrastructure for future development. Their strategies provide a roadmap for wastewater utilities committed to continuous improvement.

Clarksville’s 4 mgd per day wastewater plant serves 6,500 customers in this southern Indiana community. The plant is a trickling filter facility with primary and secondary sedimentation. The effluent undergoes chlorination and dechlorination before discharge into the Ohio River. Aerobic digesters stabilize the residuals before disposal. The collection system consists of 70 miles of sanitary sewer lines and 33 lift stations.

The town of Clarksville was committed to improving its wastewater system’s performance. Working with American Water, the town set priorities, defined an aggressive program of infrastructure improvement and maintenance and committed $6 million to a five-year rolling capital improvement plan.

Systematically controlling odors

When American Water began operating the Clarksville facility in September 2001, the neighborhood around the plant was plagued with odors. With an average of 19 years of experience, the Clarksville staff was well qualified to conduct a comprehensive odor control study. The scope of the study included:

• Chemical treatment evaluation—the team took dissolved oxygen, dissolved sulfide and ambient air hydrogen sulfide readings throughout the collection system. Chemical treatment to control hydrogen sulfide gas was changed from ferric chloride to magnesium hydroxide; and
• Influent structure condition assessment—the team determined that the plant’s influent channel and headworks were causing surcharges in the 36-in. pipe entering the facility. The surcharge blocked the air from entering the influent structure, where the air scrubber could treat the hydrogen sulfide, displacing the air at upstream manholes. Based on American Water’s recommendation, Clarksville rehabilitated the influent structure to handle additional flows.

The improvements were evident as hydrogen sulfide levels declined by more than 90% while chemical and power costs were cut by more than $50,000 per year. But most importantly, the number of odor complaints around the plant area declined from 96 in 2001 to zero in 2004.

John Minta, Clarksville council president said, “By partnering with American Water, not only have we improved the wastewater treatment facility for the people of Clarksville, but we have delivered significant cost savings too.”

Managing maintenance to reduce overflows

Clarksville’s three-pronged maintenance management program helps ensure maximum transmission efficiency in the collection system and minimal overflows to the environment.

For collection system maintenance, American Water cleans the entire collection system every three years and includes chemical root control in the system flushing program. This comprehensive approach reduces sewer backups and helps staff identify system problems in their early stages.

While proactive system improvements incorporate smoke testing and televised line inspection, the team identifies potential rehabilitation projects with good cost/benefit potential. A recent road renovation project provided an opportunity to rehabilitate a critical collection pipeline using cured-in-place pipe repair.

The final piece of the program includes the critical system backups. Clarksville’s investment in emergency generators and portable pump connections for lift stations has provided a needed backup in case of power outages. A SCADA monitoring system and autodialers, installed in 2001, allow the team to catch potential problems quickly.

Four years of operations demonstrated the program’s benefits—an 87% reduction in system overflows and a nomination for the 2005 USEPA Region 5 Operation and Maintenance Award.

A focus on continuing education involving safety-related issues plays an import role in the success of the facility as well.

Officials at the Clarksville wastewater treatment plant pointed out that in a typical year, employees could receive 28 continuing education units of safety training.

The numbers prove Clarksville’s safety commitment—nine years with no lost-time injuries and a safety rating that has improved from 72 to 100% in four years.

“Plant safety is critical to our role as stewards of the environment,” said Frank McClellan, safety coordinator at the wastewater treatment plant.