Effectiveness of Stormwater Treatment
CLIENT: Florida Department of Environmental Protection (Contract No. WM 797)
CONTACT: Eric L. Livingston (850-245-8430)
PROJECT DATES: March 2001-December 2002
PROJECT DIRECTOR: Dr. Harvey H. Harper, P.E.
FIELD OPERATIONS SUPERVISOR: Chip Harper
LABORATORY DIRECTOR: Vanessa Permaul
PROJECT BUDGET AND SCHEDULE
PROJECT COST: $167,994.92
Although dry detention stormwater management systems have been commonly used in the Florida Keys, no previous research has been performed to evaluate the effectiveness of these systems for retaining stormwater pollutants and preventing downward migration of pollutants into shallow groundwater. This project was conducted to evaluate the performance efficiency of a dry detention pond constructed in the Florida Keys, with particular emphasis on shallow groundwater impacts resulting from infiltration of runoff into the bottom of the detention basin, as well as deeper groundwater impacts resulting from the use of injection drainage wells for disposal of the treated runoff.
Field monitoring was performed by ERD at the Key Colony Beach site from July 2001-November 2002. Work efforts included field instrumentation of the dry detention pond, followed by a 16-month period of field monitoring to define water quality and hydrologic characteristics of the system. A complete hydrologic budget was performed on the dry detention facility, including direct measurement of inputs from stormwater runoff and direct precipitation, with losses occurring as a result of infiltration into shallow groundwater, evaporation, and discharge into the drainage well. Chemical analyses were also performed on inputs into the pond from stormwater runoff and bulk precipitation, along with pond surface water and discharges into the injection wells. Shallow and deep groundwater characteristics were also evaluated to identify potential groundwater impacts. In excess of 280,000 separate hydrologic and laboratory measurements were generated during the course of this project.
RELEVANT WORK PRODUCTS
- Installation of detailed hydrologic monitoring network to monitor surface and groundwater inputs and losses
- Detailed evaluation of the hydraulic performance of a dry detention system operated under high groundwater table conditions
- Evaluation of the pollutant removal effectiveness of a dry detention stormwater management system operated in an area of porous soils and high groundwater table conditions
- Installation of shallow monitoring wells and evaluation of shallow groundwater impacts resulting from infiltration of runoff through the pond bottom
- Evaluation of the deep groundwater impacts of using drainage/injection wells for disposal of treated runoff
- Detailed statistical evaluation of collected data
- Provide recommendations for improvement of the current design for dry detention systems to enhance the hydraulic and pollutant removal effectiveness of these systems and to minimize impacts on shallow and deep groundwater resources