The committee’s discussion about stormwater management highlighted the multifaceted considerations required to handle runoff effectively. Key points included the use of storm volumes and intensity duration frequency (IDF) curves established by the state of Florida, with an understanding of the limitations regarding storm forecasting. Emphasizing the importance of monitoring both the volume and rate of stormwater runoff, the committee focused on discharge control structures to regulate the flow. Groundwater dynamics, the impact of confining layers on closed basins, the challenges posed by continuous high rainfall, and the potential impact of future rainfall patterns on regulations surfaced as central themes.

Attention was given to the necessity of stormwater treatment in accordance with state and federal guidelines, acknowledging the county’s limited expertise in this domain. Members discussed specific criteria for impaired water bodies and the treatment of pollutants like nitrogen, phosphorus, and heavy metals. The efficacy of pre-treatment methods, such as dry ponds, to achieve higher removal rates for these pollutants was recognized.

The conversation also gravitated towards the setting of road and parking elevations, crucial for stormwater management and flood prevention in new subdivisions. A debate emerged on the historical rise in the seasonal high water table, with some skepticism due to a lack of historical monitoring data. Climate change’s impact on groundwater levels was a concern, particularly regarding the implications for floodplains.

Furthering the discussion on floodplains, committee members explored the accuracy of flood maps. They acknowledged the limitations of previous flood maps, which were based on less precise contour maps and overlooked small closed basins. Saltwater intrusion along the coast and its monitoring in drinking water wells in susceptible areas were also examined. The reliability of soil staining methods for establishing water table levels was another point of interest, with the committee referencing iron and salt deposits as soil indicators.

Looking towards future flood conditions, members referenced federal climate research and projections of increased rainfall. The committee considered the need to adjust current factors to account for these projections, integrating forecasting data into regulatory standards to address the anticipated changes in precipitation levels. The importance of including safety factors in design and construction to mitigate potential risks associated with a changing climate was underscored.

Accuracy of FEMA flood insurance rate maps (FIRMs) and the evolution of mapping methods with improved technology were also on the agenda. Discussions revolved around the various flood zones designated in the FIRMs, the factors contributing to map accuracy, and the reliability of soil staining methods for determining water table levels.

One particular case study discussed was the Hampton Insight area and the Lake Gertie Basin, using a USGS quad map to explain the topography and drainage patterns. The importance of understanding elevations and identifying basin lines to predict water flow was highlighted. An engineering plan exhibit was presented, showing ground elevations and site contours, and the discussion included stormwater calculations for pre- and post-development conditions.

The committee also revisited a stormwater pond built in 2014, which has been functioning without issues, serving only a hotel. The impact of stormwater ponds on surrounding groundwater and neighboring properties led to a debate on the need to update stormwater rules. Furthermore, challenges in drainage design, potential reasons for engineering failures, and updates to standards to account for natural disasters like hurricanes were debated, alongside the implications of using a 25-year versus a 100-year standard for stormwater management.

Lastly, stormwater management was linked to financial aspects, with the utilization of stormwater fees for capital projects to combat flooding and water treatment issues taking center stage. Possible increases in stormwater fees and the allocation of funds for studies and projects were discussed. The committee also noted an upcoming workshop on zoning and permitting, expressing interest in how it might inform their ongoing environmental and regulatory efforts.