Sewer district plans $85.9 million in upgrades

Plans are still under way for the Little Blue Valley Sewer District’s $85.9 million in improvements.

Such improvements will begin in the summer of 2011 and will continue through the spring of 2014. With its customer cities including Independence and Blue Springs, sewer district officials presented an update on upcoming improvements Monday night to the Independence City Council.

The council plans to consider a resolution supporting the project since the sewer district requires 75 percent customer approval before moving forward. The district will use Build America taxable bonds by the end of 2010 to finance the improvements. The bonds, part of the federal economic stimulus effort, aim to reduce the cost of borrowing for state and local government entities.

Through the bond repayment, the project may have a 6 percent maximum single-year increase on customers, compared with a 6.75 percent maximum single-year increase based on the existing sewer district budget.  

Involving the solids portion of the wastewater treatment process, the planned improvements include the replacement of aging biosolids equipment, meeting new disinfection regulations and managing peak wet weather flows.

Biosolids capacity and maintenance: Constructed in the mid-1980s, the sewer district’s biosolids incinerator is designed for a capacity of 40 million gallons of wastewater per day. However, the district is now experiencing 50 million gallons of wastewater per day, and that’s expected to increase to 52 million gallons per day by 2020. A new $49.6 million incinerator will be constructed to address biosolids capacity and maintenance.

The plant’s incinerator and sludge conditioning system also have reached their design life, said Stan Christopher, a consultant with HDR Inc. and the project manager. According to Christopher, the existing sludge conditioning system is a potential odor source and also effects the proposed disinfection process.  

Disinfection: The district would build an ultraviolet light disinfection facility. The sewer district must comply by December 2013 with state regulations adopted five years ago.

The $22.7 million facility will have the capacity to disinfect up to 150 million gallons of wastewater per day. The stakeholder group also considered a chlorine disinfection facility as an option.

“Ultraviolet is a cleaner operation, and chemicals will not be involved on the plant site on a daily basis,” Christopher said. “It does use slightly more electricity, but all in all, it has a better carbon footprint and is more socially acceptable.”

Ammonia removal: The sewer district had considered ammonia removal as part of this round of improvements but determined the improvements made in 2001 were adequate.   

“Right now, our plant is doing very well in meeting those ammonia limits,” said John Reece, the sewer district’s executive director, “but in the future, we see more stricter limits and we’ll probably have to keep doing additional modifications for our liquid portion of the plant in order to reduce our ammonia discharge.”

Conveyance: Conveyance, or the means by which water is transferred from one point to another, is among the biggest challenges that cities encounter with wastewater treatment, Christopher said.

Significant rain can increase the sewer district’s flow to more than 200 million gallons per day. In some cases, Reece said, flows as high as 400 million gallons per day have taken place. (Infiltration and inflow is known as excess water that flows into sewer pipes from groundwater and stormwater.)

“We need to get a better handle on our peak wet weather flows,” Reece said. “We’re continuing to work with our customers and customer cities, encouraging them to address the infiltration/inflow issues, not only in their system but also to make improvements such that we can, over time, reduce that infiltration/inflow.”  

The sewer district recommended the following measures in addressing wet weather issues: encourage customers, including the city of Independence, to continue efforts to reduce infiltration/inflow; and construct a new $13.6 million excess flow holding basin at Interstate 470 and Raytown Road to hold excessive flows during peak flow times.

Improvements completed between 2001 and 2006 involved the liquid portion of the treatment process and included odor elimination, expanding the district’s liquid capacity in millions of gallons per day and ensuring more effective metering accuracy.