St. Johns County Deep Creek Regional Stormwater Treatment Facility

Project Description

St. Johns County receives nutrient-removal credits as part of the Lower St. Johns River (LSJR) Basin Management Action Plan (BMAP) for the long-term maintenance of the Deep Creek West (DCW) Regional Stormwater Treatment Facility (RST) built and owned by the St. Johns River Water Management District (SJRWMD). Based on initial investigations and studies, potential additional cost-effective nutrient-removal opportunities exist at the Deep Creek RST. As part of the Preliminary Engineering Report, Jones Edmunds worked with SJRWMD to verify current DCW nutrient-removal performance and identify system modifications that could increase nutrient-removal performance. During the initial phase of the project, a 30% design was prepared for the intake, forebay, wet detention pond (two alternatives), pond outfall, and wetland bypass. All of these elements were taken to final design. The design recommendations included:

Forebay

• Expand the opening to allow canals to become part of the pump station working volume.
• Reconfigure the screen between forebay and wet well.

Pump station

• Add backflow preventers on the existing pumps.
• Add pump(s) with lower flow rates than the existing pumps.

Pond

• Raise the existing berm to increase volume.
• Expand the pond footprint.
• Expand the pond footprint and raise the berm.
• Adjust the pond outfall structure.

Wetland

• Raise the perimeter berm elevation.
• Partially regrade the wetland to reduce short-circuiting.

The second phase of this project was to prepare final design modifications to the DCW RST. Jones Edmunds worked collaboratively with the County and the SJRWMD to develop site investigations, construction drawings and specifications, and opinion of construction cost. Jones Edmunds also assisted the County procure $500,000 in grant monies from SJRWMD.