The Use of SF<sub>6</sub> and GIS to Study Farfield Modeling of Ocean Outfall Plumes in Florida

Abstract

In June, 2004 and February, 2007, in field tracer studies were conducted on the Hollywood and South Central outfalls, using sulfur hexafluoride (SF6) as a tracer. The objective of these studies was to determine if the tracer could be detected in the farfield at significant distance, and if so, could this data be used to construct a model of the farfield plume. Prior models for farfield plume movement do not appear to comport well with the conditions in southeast Florida. Extensive research was conducted in southeast Florida on 4 outfalls, which led to the development of nearfield dilution equations for same. However farfield modeling of outfall plumes was difficult to accomplish because the tracers used are not detectable for significant distances. The SF6 resolved that problem and as a result the Hollywood outfall was used to construct a model. Two methods were investigated for modeling the plume, 1) the Eureqa formulation method and 2) the Gamma-Curve method. The concentrations in the x-y plane were first found by using the Eureqa formulation to calculate the concentration at each grid point given its depth and the concentration of the centerline at the same latitude. The plume models were generated using MATLAB that matched with the results actually seen in the field.

Faecal pollution along the southeastern coast of Florida and insight into the use of pepper mild mottle virus as an indicator

“…2Á6 million people (U.S. Census Bureau 2014). ; Rosario et al 2009;Bloetscher et al 2011;Futch et al 2011;Bloetscher et al 2014). The major source of faecal pollution to the coastal marine environment varies depending upon the surface currents, with both inlets and ocean outfall surface boils having tested positive for human and zoonotic pathogens (e.g.…”

“…2Á6 million people (U.S. Census Bureau 2014). This area has a long history of faecal pollution because domestic wastewater is treated via on-site septic systems abutting inlets or by one of two wastewater treatment plants (WWTPs) that discharge secondary-treated, chlorinated effluent via ocean outfalls (Bloetscher et al 2011(Bloetscher et al , 2014. The major source of faecal pollution to the coastal marine environment varies depending upon the surface currents, with both inlets and ocean outfall surface boils having tested positive for human and zoonotic pathogens (e.g.…”

“…norovirus, Giardia spp. ; Rosario et al 2009;Bloetscher et al 2011;Futch et al 2011;Bloetscher et al 2014). The WWTP ocean outfalls are located several kilometres offshore where the Florida Current usually prevents the onshore movement of surface boils.…”

“…The southeastern Florida coast is exposed to mixed domestic wastewater pollution; ocean outfalls are a source of secondary-treated, chlorinated wastewater, which may contain infectious pathogens (Rosario et al 2009;Bloetscher et al 2011Bloetscher et al , 2014Futch et al 2011) and inlets are exposed to leaking septic systems that may offer little to no treatment (Meeroff et al 2008;Futch et al 2011;Carsey et al 2012;Campbell et al 2015). The primary objective of this study was to determine the extent of domestic wastewater pollution from point and nonpoint sources along the southeastern Florida coast.…”