Hydraulic Analysis of Orlando Easterly Wetland

Abstract

Hydraulic testing of the Orlando Easterly Wetland, a constructed treatment wetland located near Christmas, Fla., was performed as part of a more comprehensive study of treatment efficacy of the system. The wetland serves to reduce nutrient loading from tertiary treated wastewater to the St. Johns River, the receiving body. Residence time distribution analysis of bromide tracer tests revealed and quantified inefficiencies (short circuiting and dead zones) in the hydraulic performance within individual treatment cells and the wetland system under the operating conditions studied. Hydraulic efficiencies (ratios of experimentally determined residence times to nominal residence times) of the cells ranged from 11 to 88%, while overall, the wetland was operating at near 50% efficiency during the tracer tests. Short circuiting and dead zones within the wetland are largely the results of historic land alterations, such as ditches, that were not removed during the conversion of the site from drained land to managed wetland. Volume- and area-based system-referenced metrics were developed to identify and prioritize opportunities to improve hydraulics on both cell-by-cell and system scales.