section 4 - existing conditions and needs - Martin County, Florida

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4.3.3 Port Salerno Platted as Port Salerno in 1912, the subdivision is one of the oldest in Martin County. The Salerno Creek Water Quality Retrofit was constructed to improve the water quality discharging into Manatee Pocket. Existing isolated roadside swales and ditches provide drainage to local streets, including S.E. Salerno Road and the Port Salerno Elementary School ditch. The County is aware of recurring flooding at the intersection of S.E. Salerno Road and Flounder Avenue. In addition, there is flooding in the upstream reaches of the elementary school ditch. Manatee Creek 4.4 EXISTING CONDITIONS – STORMWATER MODEL Port Salerno 4.3.4 Manatee Creek The main access to the subdivision is provided by S.E. Primrose Way at Cove Road. Dead end streets characterize the layout of the subdivision. Stormwater treatment areas recommended in the Manatee Creek Stormwater Quality Retrofit are currently under construction to provide water quality treatment to this area of the CRA. Phase I is under construction, and Phases II and III have been designed. In order to confirm reports of existing stormwater deficiencies and to identify additional areas of concern, stormwater modeling was conducted using the available data for existing conditions within the Port Salerno CRA. The model used for this existing conditions study was the Interconnected Channel and Pond Routing Model (ICPR). This model was selected in order to be consistent with methodology used in the proposed Stormwater Master Plan modeling included under Section 5. The Port Salerno CRA was divided into existing drainage basins according to existing contour maps, basin maps, and stormwater reports. For basins studied and not modeled, the information was incorporated where applicable. Pervious and impervious areas within each existing drainage basin were determined using building area information provided by the Martin County Tax Assessment Office with additional area MARTIN COUNTY STORMWATER/UTILITY CRA MASTER PLAN – PORT SALERNO CRA SECTION 4-4 EXISTING CONDITIONS AND NEEDS (07/03/06)
calculations based on existing plans and current aerial photographs of the CRA as provided by Martin County. Based on soil conditions and depths to water tables as indicated in Figure 10, “Soils Map” along with the calculated impervious areas, a Curve Number (CN) was determined for each basin. Stage/storage calculations for the model are based on the existing contour map. In order to account for the high permeability of the existing soils in the east Port Salerno area, a stage discharge rating curve was developed for those areas using the soils data and hydraulic conductivity in the Martin County Soil Survey. Stormwater models were run (see Appendix - Pre-redevelopment ICPR Model) for each basin using a 10 year 1 day design storm event of 7” inches of rainfall, the 25 year 3 day design storm event of 12” inches of rainfall, and the 100 year 3 day storm event of 14” inches of rainfall. The design storm rainfall totals are from the SFWMD, Volume IV, Surface Water Design Aids, Figures C-6, C-8, and C-11 (see Appendix – Rainfall Information). The stormwater model results show maximum stages within each basin for the design storms. These stages were compared to the existing contours within the basin to determine the potential level of flooding. The modeling effort is based on available information and has not been calibrated using actual specific soil test data or specific elevations within the existing basins. Therefore, the results of the modeling provide general information on potential areas of concern. In order to conduct an in-depth analysis, it would be necessary to obtain specific geotechnical information and to perform field survey the areas in question. 4.5 STORMWATER SYSTEM LEVEL OF SERVICE DEFICITS Approximately 40% percent of the area within the Port Salerno CRA is served by existing conveyance and flood protection facilities providing an adequate LOS. Areas within the Port Salerno CRA currently not served by regional conveyance and stormwater treatment areas/systems are considered to be deficient relative to the LOS definition. In addition, there are a number of areas serviced by inadequate infrastructure. While these systems are sufficient for providing the daily drainage needs of the area, they are insufficient when compared to the current LOS criteria needed for water quality, stormwater attenuation, and basic flood protection. In addition to the LOS considerations, the analysis included a review of nuisance flooding concerns. Although most residents do not have structure flooding, they may encounter nuisance ponding in front of their homes and businesses. It should be noted the cost of removing all the nuisance ponding may be expensive and the benefit to the drainage systems LOS may be minimal. In discussions with Martin County staff, several areas of concern were identified. Specific information on these areas is shown Section 4.6, Summary of System Deficits. The American Red Cross provided information related to flooding during 1995, 1999, and 2000. The Martin County Health Department did not indicate specific concerns about failed onsite sewage disposal (septic) systems within the Port Salerno MARTIN COUNTY STORMWATER/UTILITY CRA MASTER PLAN – PORT SALERNO CRA SECTION 4-5 EXISTING CONDITIONS AND NEEDS (07/03/06)
Page 1 and 2: 4.1 BACKGROUND SECTION 4 - EXISTING
Page 3: Port Salerno Elementary School 43-0
Page 7 and 8: Each of the neighborhoods previousl
Page 9 and 10: 4.8.3 Port Salerno The Port Salerno
Page 11 and 12: Current County customers in the Por
Page 13 and 14: − Centralized potable water servi

section 4 - existing conditions and needs - Martin County, Florida

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