| DRAINAGE OVERVIEW | |
| Where does the Storm water Go?
To fully understand the existing drainage patterns and storm water facilities along the Midway Road corridor, Brian Good, P.E. has made numerous site visits to evaluated existing drainage patterns, met with Mr. Ray Murankus of St. Lucie County Engineering Road and Bridge Department and spoken to Mike Brock of St. Lucie County Public Works Department to discuss historical drainage and maintenance problems located along the study corridor.
For discussion purposes, we have broken down the Midway Road corridor into three segments:
Segment No. 1 (South 25th Street to the North Fork of the St. Lucie River) Storm water runoff along this segment of Midway Road sheet flows to roadside swales located within the County right-of-way. These roadside swales convey the storm water runoff to the east, where the runoff is discharged into a tributary of the North Fork of the St. Lucie River. There is no storm water management facilities located along this segment of Midway Road that provide water quality treatment or storm water attenuation prior to discharge into the St. Lucie River.
Approximately 2000 feet east of S. 25th Street lies a 29”x45” cross drain culvert, which hydraulically connects the open channel swale located along the north side of Midway Road to the St. Lucie River tributary. Segment No. 2 (North Fork of the St. Lucie River to Oleander Blvd) This segment of the corridor lacks any defined storm water collection and conveyance facilities. There is no storm water management facilities located along this segment of Midway Road that provide water quality treatment or storm water attenuation prior to discharge into the St. Lucie River. Storm water runoff from within the roadway sheet is from the roadway right-of-way to depressional storage areas located along the north and south sides of Midway Road.
Segment No. 3 (Oleander Boulevard to US 1) Storm water runoff from this segment of Midway Road is collected in a combination of catch basin inlets and roadside swales. One of two storm water management facilities located along this portion of the corridor is in the northeast quadrant of the Oleander Boulevard / Midway Road intersection. A dry detention swale was constructed to provide water quality and quantity treatment to accommodate the roadway improvements that were construction at the intersection. This swale discharges into Merritt Ditch immediately east of Oleander Boulevard. During the time of the intersection improvements a 48” storm sewer culvert was constructed along the eastside of Oleander Boulevard to accommodate discharges associated with future development located along Oleander Boulevard south of Midway Road.
Floodplain Considerations The Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps indicate that the portion of the Midway Road study corridor from S. 25th Street to just east of the North Fork of the St. Lucie River is designated as Zone AE (100-year flood elevation determined). The 100-year flood is estimated to reach an elevation of 8.80 NGVD29. The remaining Midway Road corridor, east of the St. Lucie River to US 1, is designated Zone X (areas outside of the 100-year flood). Proposed Drainage Design Considerations Our key objective for the storm water management system will be to provide a roadway corridor that is safe to travel during inclement weather, elevates existing drainage problems, is easily maintained, and is the most cost-effective alternative. The storm water management system will be designed to meet SFWMD criteria for water quality and quantity and FDOT criteria for roadway drainage and quantity considerations. What’s a good storm water facility for you? Selecting the appropriate method and right location for storm water treatment and attenuation is a key component of the PD&E process and is qualified in the Pond Sitting Report. Topography, soil conditions, groundwater, natural resources are just a few of the items that need to be considered in the study to result in a successful project. Our team has a greet appreciation for the natural beauty and characteristics that the White City community has to offer. In addition to the key objectives previously identified for the drainage design, preserving and enhancing the natural resources that the community has to offer is of high priority to our team. |
The County has installed 29”x45” elliptical storm sewer culverts located on the north and south side of Midway Road. These culverts extend from the west side of S. 25th Street to approximately 1100 feet east of S. 25th Street, where they discharge into the open channel swale system. Based upon our conversations with St. Lucie County, these culverts were sized to accommodate future development along Midway Road, west of S. 25th Street. 
Through this portion of the corridor there exists only one cross drain that allows approximately 3 acres of off-site contributing area to drain north, under Midway Road to Merritt Ditch. Merritt Ditch conveys storm water runoff from the east to the west, and is located approximately 800 feet north parallel to Midway Road. Merritt Ditch is the primary means by which storm water runoff from Midway Road and its surround property is conveyed to the North Fork of the St. Lucie River.
Located approximately 1000 feet east of Oleander Boulevard, there is an 18” cross drain that allows approximately 18 acres of agricultural property located along the south side of Midway Road between Oleander Boulevard and Melville Road to drain north to Merritt Ditch.