New Castle's wastewater treatment plant lagoon got a thorough plunging Monday.
Once a year, workers clear out the city's storm surge equalization basin, known as “the lagoon,” scraping accumulated inches of sludge from the bottom. The lagoon gathers water to prevent combined sewer overflows.
If a large storm sends more water than the wastewater plant's capacity to process it, water overflows and is sent straight into the Big Blue River. Rains heavy enough to create a potential overflow occur about 8 to 10 times a year, said Fred Duvall, Water Pollution Control Superintendent.
Duvall said all manner of trash could end up in the lagoon if New Castle didn't clear out sewers with industrial Vactor suction trucks. Special grates installed at the mouth of eight storm combined sewer overflows around New Castle also serve as preliminary catch-alls to prevent litter from making its way to the Big Blue River and clogging up the works.
“The average person has no idea what it takes to run this facility,” Duvall said. After sludge leaves the lagoon, it is pumped 1,500 feet to the drying beds, and then is delivered to the landfill in Big B rubbish containers that hold 30 cubic yards each for sludge disposal.
Total cost of the annual cleanout will be $8,000 to $10,000, Duvall said. To wait longer than a year would drive the cost up, requiring more manpower and equipment.
