Municipal Wastewater Recharge to the Groundwater System

Client: Collier County, Florida

Location: Collier County, FL

Summary: Collier County, Florida desired to utilize an infiltration basin system for sustainable management of reclaimed wastewater. The recharge system was developed in a wetland area to be isolated and confined from the surrounding properties so that no surface water discharges would result. Within the immediate area of the project, the groundwater system experiences heavy use for both irrigation and potable water supply, and the shallow freshwater aquifer system has long history of problems with saline water intrusion. The effluent recharge system was intended to benefit the system by providing additional water to the shallow aquifer system and reduce stress of over pumpage. The issue of groundwater recharge was complicated by public concerns that recharge of treated effluent into the groundwater resource that was utilized for raw water supply to a regional potable water utility.

The ENTRIX work scope involved an investigation to characterize the hydraulic nature of the aquifer system and to define direction and rate of movement of the recharge plume from the infiltration area. Work elements included drilling and groundwater testing to establish hydraulic characteristics and the regional flow directions. A computer model was developed to define the groundwater mounding resulting from the wetland recharge operations, and the interaction of the groundwater mound with the drainage system and neighboring tidally influenced water bodies. Water quality analysis was conducted to identify the nature of the reclaimed water after it had been recharged to the groundwater system. A comprehensive groundwater monitoring system was developed to address the impacts on the aquifer system.