60,000 Gallon Per Day Leachate Treatment Facility Design, Southeast County Landfill in Hillsborough County, FL

Hillsborough County needed a long-term plan for managing leachate at the Southeast County Landfill. The County wanted to carefully evaluate its options, so it retained SCS to conduct a feasibility study.

SCS’s analysis included biological, physical, and physicochemical treatment processes and off-site disposal at a publicly-owned and operated wastewater treatment facility. Considering the County’s desire to manage leachate on-site, SCS recommended an on-site treatment system, with effluent disposal through a spray irrigation system over completed sections of the landfill.

Challenges and Solutions

The primary constituent of concern was ammonia; SCS selected an activated carbon treatment process, which included nitrification and denitrification unit processes. The design is based on leachate generation estimates using the EPA’s Hydrologic Landfill Performance Model (HELP) and leachate characterization studies. The system includes a 570,000-gallon leachate storage tank, full secondary containment system for treatment and storage vessels, effluent storage pond, and a 21-acre leachate spray field.

SCS successfully addressed regulatory concerns throughout the project. The Florida Department of Environmental Protection (FDEP) instituted stringent spray irrigation limitations on the system based on rainfall patterns. SCS adapted the leachate management plan for the site to accommodate the limitations.

SCS has also provided ongoing operational support for the treatment plant, including the following:

  • Oversight of the rehabilitation of five leachate storage tanks
  • Rehabilitating a 550,000-gallon leachate storage tank
  • Re-programming the storage tank’s active cathodic protection system

Since completion and startup, the system has effectively treated the target contaminants.