Abstract
As a means of protecting Florida's surface waters from the effects of nonpoint source pollution, regulations have been established which require new developments or projects to provide pollution abatement for a specified volume of stormwater runoff on-site. One of the most common stormwater treatment methodologies utilized in the State of Florida today for pollution abatement is the filter system. These filter systems incorporate either a wet or dry detention basin to attenuate and provide temporary storage for runoff inputs during rain events. Detained runoff then passes through a minimum of 2 feet of filter media and is collected in an underdrain system for ultimate discharge to the receiving waterbody. It is commonly thought that this filtration process attenuates many common stormwater pollutants, particularly those associated with particulate matter.
Although side bank filter systems are one of the most popular stormwater treatment technologies utilized in the State of Florida today, little previous research has been done to demonstrate the effectiveness of these systems for attenuating stormwater pollutants. Recently, concern has been expressed that suspended matter trapped by the filter system may be subject to decomposition and solubilization processes over time, resulting in a gradual release of the particulate matter originally trapped within the system. Questions have also been raised concerning the hydraulic effectiveness of various filter media and filter configurations. The effectiveness of various sod media in improving the pollutant attenuation capabilities of filter systems have also been questioned.
In 1990, the St. Johns River Water Management District (District), as part of the Surface Water Improvement and Management (SWIM) Program, selected Environmental Research & Design, Inc. (ERD) to study the effectiveness of a wet detention pond with side bank filters in the lower St. Johns River Basin. This study included field instrumentation of a wet detention with filtration site and a six-month period of monitoring to define water quality and hydrologic characteristics of the system. In addition, pilot scale studies were conducted to evaluate the hydraulic efficiency and pollutant removal effectiveness of various filter media and sod cover for use with side bank filter systems. The results of this study will be used to refine design, operation and maintenance practices for filter systems and to support future District rule revisions.
The research efforts described in this report present a detailed investigation of the hydrology, hydraulic performance and water quality characteristics of a wet detention with filtration system located in DeBary, Florida. In addition, the results of pilot studies are also presented which evaluate the hydraulic and pollutant removal effectiveness of various filter media and sod configurations. Field investigations and laboratory studies began in April 1992 and continued through January 1993. In excess of 48,000 separate field and laboratory measurements were generated during the course of this project.
This report is divided into two separate volumes. Volume I is titled "Treatment Efficiency for Detention with Filtration -
Volume I" and contsis of a literature review of previous work efforts conducted on filter system, a discussion of field and
laboratory procedures, a presentation of the experimental results and conclusions, along with
Appendices A through Z with the exception of Appendix E and Appendix F. Appendix E and Appendix F
are contained in Volume II which is titled "Treatment Efficiency for Detention with Filtration -
Volume II - Appendix E and Appendix F". These appendices contain a complete listing of inflow
and outflow hydrographs at the detention with filtration pond site from June through November 1992.
The size of this information necessitated that these appendices be bound in a separate volume.
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