St. John’s County Masters Tract Regional Stormwater Treatment Facility
St. Johns County is required to implement projects to reduce nutrient loads to the Lower St. Johns River (LSJR) to meet the Total Maximum Daily Load (TMDL) compliance goals of the LSJR Basin Management Action Plan. To assist the County, Jones Edmunds prepared a Preliminary Engineering Report (PER) and helped with the design, permitting, and construction-phase services for the Masters Tract Regional Stormwater Treatment Facility.
Masters Tract is a 272-acre parcel owned by St. Johns County adjacent to Deep Creek, a tributary of the LSJR. Stormwater runoff from upstream areas is negatively impacted by agricultural uses, resulting in high nutrient loads to Deep Creek. The design focused on optimizing nitrogen removal through multiple treatment methodologies including wet pond construction, stormwater harvesting, infiltration canals, and constructed wetland communities. Jones Edmunds completed extensive wetland field investigations to delineate all on-site wetlands, identify wetland mitigation areas, and determine wetland creation design elevations using Deep Creek floodplain wetlands. We also provided a Phase I Environmental Assessment and soil nutrient for the County.
The project included routing incoming creek flows to a stormwater pump station that discharges to a regional stormwater basin for initial treatment and nutrient removal. Water is then routed to agricultural irrigation (i.e., stormwater harvesting), two large emergent marsh flow-ways, or a series of three 13+-acre treatment wetland cells for further water-quality polishing. A key element of the project provides the ability to use excess stormwater for irrigation of a nearby farm that is currently using groundwater.
In addition, the project provides 21 wetland mitigation credits (valued at approximately $2.1M) generated by the constructed wetlands to offset the future County Capital Improvement Program wetland impacts. Jones Edmunds assisted the County in securing $2.9 million in grant funding and is providing grant administration and construction services.