BCC’s Water Resources Team was responsible for designing two drainage segments: Segment 2B and Segment 4. Segment 2B includes the area along 118th Avenue, SR 690 and SR 686 from south of 40th street to 28th street, proposed SR 690 viaduct and the 118th Avenue north flyover. Segment 2B is divided into six basins with 137 drainage structures, a new wet pond and nine existing ponds with minor pond/control structure modifications. Segment 4 begins from south of Gandy Boulevard to north of 4th Street North, connecting from the SB I-275 express lanes to WB Gateway Expressway and from EB Gateway Expressway to the NB I-275 express. The drainage improvements include new on-line dry detention/retention swales, modification to existing on-line dry detention ponds, re-grading infield ponds and the installation of the new control structures divided into 31 drainage basins with 349 drainage structures, the extension of three Concrete Box Culvert (CBC), 3 pipe culverts, construction of new or re-grading of 9 ponds, 17 swales and installation of 11 miles of concrete pavement subdrainage (edgedrain).

The project corridor is located within the jurisdictional boundary of the Southwest Florida Water Management District (SWFWMD) and will also conform to any additional design requirements of the Florida Department of Environmental Protection (FDEP) and United States Army Corps of Engineers (USACE), as well as the Florida Department of Transportation (FDOT), District 7.

The proposed stormwater management facilities have been designed to meet the SWFWMD water quality and water quantity criteria, with consideration of several design constraints, including avoiding right-of-way acquisition, avoiding and minimizing wetland impacts along the project avoidance, and minimizing impact to sensitive upland landscape. No permanent and secondary impacts, other than what already has occurred by construction of the conceptual approved permit.

These facilities are designed to treat and attenuate the SWFWMD requirement of runoff from impervious area due to project discharge into Outstanding Florida Water (Old Tampa Bay). The proposed stormwater management facilities will provide the necessary water quality treatment volume and limit the peak discharge rate into all receive body water to the pre-development peak discharge rate.

Software used during drainage design:

• Advanced Integrated Channel and Pond Routing (AdICPR) v3- for water quantity (peak discharge rate into all receive body water pre. Vs postconditions and peak stages)
• PONDS v3.30278- to estimate the retention recovery time and Total Maximum Daily Load (TMDL)
• Automated Strom Sewer Analysis ASAD v3- for storm drain system analysis.
• Culvert Master v3.3- for culverts analysis.
• Culvert Service Life Estimated (CSLE)- for Optional Pipe Material calculations.