Abstract
State Water Policy, provided in Chapter 62-40 FAC, provides general guidelines related to water use, water transport, water quality, surface water management, and resource protection and management. Many of the existing stormwater treatment design regulations are a result of the requirements of Chapter 62-40. While State Water Policy states that stormwater treatment facilities shall be designed to achieve 80% and 95% reductions of pollutant loadings, minimal research has been performed relating current treatment volume requirements to pollutant load reduction efficiencies for various stormwater management systems.
In 1994, Environmental Research & Design, Inc. (ERD) developed a basic methodology to evaluate the effectiveness of treatment volume requirements in meeting the State Water Policy pollutant load reduction goals. Five different stormwater treatment alternatives were evaluated including off-line retention, on-line retention, a combination of off-line retention and wet detention (14-day residence time), a combination of off-line retention and wet detention (7-day residence time), and a combination of off-line retention and dry detention. Based on hourly rainfall data, annual rain events were divided into 11 rainfall intervals. The runoff for each rainfall interval was calculated for three different types of developments, including low-density, medium-density and high-density. Different treatment volume requirements for each of the five stormwater treatment alternatives were evaluated with the goal of achieving 80% pollutant load reductions for total phosphorus, total nitrogen and total suspended solids on an annual basis. The results of the analysis indicate that many of the present stormwater treatment volumes used within the State of Florida do not meet the 80% and 95% pollutant load reduction goals provided in State Water Policy.
While this basic methodology to determine stormwater treatment volume requirements to meet State Water Policy
pollutant load reduction goals included many assumptions, it is a step forward in correlating treatment volume requirements
to pollutant load reduction goals. A great deal more research and evaluation is needed to better understand the relationships
between stormwater treatment volume requirements and pollutant removal effectiveness.
Return to Technical Papers