One of the city's biggest infrastructure projects in recent years is nearing completion, and with it the possibility for the city to expand in areas it could not before.
The city’s new sewage treatment plant just south of the Wakarusa River is undergoing final inspections and is scheduled to open next month. The more than $74 million Wakarusa Wastewater Treatment Plant will improve the city’s ability to manage heavy rainfall and nutrient pollution as well as enable additional development.
Melinda Harger, utilities engineer for the city, said that the city’s existing sewage plant in eastern Lawrence is projected to meet capacity this year, and the new plant allows development in areas the city’s current plant can’t accommodate.
“It allows for future growth in west and south Lawrence, because there were some places that could not develop until this (plant) was here,” Harger said.
The plant, at 2300 E. 41st St. — it is basically south of where O'Connell Road ends at the Wakarusa River — will increase the capacity of the city sewer system by 2.5 million gallons per day, or by about 20 percent, Harger said. The main plant covers about 25 acres, and includes labs, water storage, control stations and nutrient-removal basins.
"It's the largest capital project the city has done in the last 10-20 years," Harger said.
The plant’s cleaning process has four main steps, Harger said: an initial grit and trash removal, biological nutrient removal, final clarification to remove solids, and disinfection via ultraviolet bulbs. She said the plant is scheduled to open in mid-March and will operate with about six staff members during the day and one at night. Lawrence's existing plant east of Eighth and Delaware streets will continue to operate.
The new plant's nutrient removal step will ensure the city meets Kansas Department of Health and Environment and Environmental Protection Agency requirements. Harger said the city must ensure that the amount of nitrogen, phosphorus and ammonia in the water released into the river are below certain levels because too much can harm the ecosystem.
For instance, too much nitrogen and phosphorus in the water — a form of nutrient pollution — can cause large algae blooms that harm water quality and decrease the oxygen that fish and other aquatic animals need to survive, according to the Environmental Protection Agency. The EPA states that nutrient pollution has impacted many streams, rivers, lakes, bays and coastal waters for the past several decades, resulting in serious environmental and human health issues.
The new plant is also designed to reduce the amount of rainwater that enters the current plant during large rainstorms, which can reduce overflows of sanitary sewers into waterways. The Wakarusa plant includes a 5-million-gallon basin that Harger said will help the city manage heavy rainfall and reduce overflows.
“During those wet weather events, some of those higher flows can be sent to the Wakarusa plant,” Harger said.
City officials previously have said the existing plant takes on about 80 million gallons of storm water and sewage during a 10-year storm, even though the plant has a design capacity of about 65 million gallons.
The new plant is being paid for through previously approved rate increases for water and wastewater. In 2013, city commissioners approved a new five-year rate plan that increases water and sewer rates by 5 to 7 percent each year.