By late 2007, the Town of Decatur’s South Wastewater Treatment Lagoon had lost so much volume that it was becoming ineffective. Approximately half the volume of Cell No. 1 had been eliminated due to accumulating sludge and the presence of sand being deposited there through the sanitary sewer collection system, which also restricted flow from the influent sewer main. Matters at the lagoon were made worse by flood damage from Hurricane Katrina and the presence of nutria burrowing into the banks. Furthermore, the influent main would flood during heavy rains, and even during dry weather wastewater overflows would spill adjacent to the East Central Alternative School, posing a health hazard to the community.
These factors finally led to so much deterioration at the lagoon that the town received a Notice of Violation from MDEQ for multiple permit violations. Decatur called on WGK, Inc., which had designed previous lagoon improvements, to rescue the South Lagoon.
Due to a lack of available property for land-applying the accumulate sludge, WGK designed a project to expand the lagoon’s banks and raise it by 2 feet, restoring the lost volume and protecting the cell against future inundation. A new influent pump station was installed to pump the wastewater the additional 2 feet and into the lagoon.
- Addition of influent suction-lift pump station
- Cell No. 1 levee raised by 2 feet
- Removal/disposal of 450 dry tons of sludge
- Replacement of 590 feet of floating baffles
- Planning, design and construction phase services
- Contractor used geotubes to passively dewater sludge
- Total Phase II Project Cost: $326,000
New wastewater treatment standards are here…
The release of new wastewater discharge permit limits next year could require extraordinary changes for smaller Mississippi towns operating treatment lagoons, while larger cities’ mechanical plants may also need some upgrades to meet the new restrictions.
The Mississippi Department of Environmental Quality (MDEQ) is developing water quality standards for nutrients in order to meet court-mandated environmental reforms authorized decades ago by the federal Clean Water Act of 1972, but not fully implemented. The new regulations will require wastewater treatment systems to meet total nitrogen and total phosphorous limits for the first time, and could render some lagoons and plants obsolete overnight.
If you are unsure of how new nutrient standards will affect wastewater treatment in your city, town or industry, WGK can chart a course for your facility’s future. Call Greg Gearhart, PE, BCEE, CEE at 601-925-4444 for an assessment of your treatment operation.