Great swamp natural effluent management system – a summary of thirteen years of operations
Introduction
High seasonal rainfall, shallow groundwater, slow-flowing rivers, and sensitive coastal environments result in challenging issues for wastewater management in coastal South Carolina. These challenges are exacerbated as more and more people move into the area. Direct discharges of treated wastewaters to surface waters are severely limited by low flow conditions and the need to protect shellfish resources in the area’s coastal rivers. While land application of treated effluent is the preferred alternative for effluent reuse and ultimate disposal, application rates to area “uplands” are often limited by marginal soil drainage and inadequate unsaturated soil depth, especially during rainy periods.
Limited wastewater disposal capacity has led the area to a wastewater management solution that integrates urban development and the area’s abundant natural aquatic resources. Pioneered at the nearby Sea Pines Plantation Forest Preserve on Hilton Head Island beginning in 1983, wet weather backup wastewater disposal incorporates compatible natural freshwater wetlands into an overall effluent management system (Knight and Ferda, 1989). This solution to the area’s increasing need for wastewater management helps to conserve natural wetland habitat in public ownership and restore previously impacted wetlands while providing an environmental reuse option for recycling treated wastewater. Furthermore, the area’s coastal waterways remain attractive for recreation while wastewater is managed in a cost-effective manner.
Section snippets
Treatment system and operating permit
BJWSA owns and operates the 28390 cubic meters per day (m3/d) Cherry Point/Okatie Area Water Reclamation Facility (WRF) in southern Jasper County, South Carolina. This oxidation ditch/activated sludge/filtration facility provides a high level of treatment for five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), and ammonium nitrogen (NH4-N), with long-term average permitted effluent concentrations less than 5,5, and 2 mg/L, respectively. Following UV disinfection, reclaimed
Methods
To evaluate the health of the wetland following the initiation of treated effluent discharge, permit conditions required baseline monitoring. Since discharge began in 1999, sampling has been completed to collect data for comparison to the baseline monitoring period. Collection of baseline data for comparison has both advantages and disadvantages. The advantages of this type of baseline monitoring are the collection of site-specific data that may be difficult or impossible to replicate in a
Hydrology
During the baseline period the primary input of water to the EMS was from direct rainfall and runoff. The dominance of natural water inputs has remained during the 13-year operational period with period-of-record average rainfall and runoff estimated at 2866 m3/d and 6892 m3/d, respectively. On average it was estimated that the 2011 reclaimed water inflow of 8823 m3/d was equivalent to about 40% of the combined inputs from rainfall and non-point source runoff.
Since project initiation in 1999,
Discussion
The NPDES permit for the Great Swamp EMS includes “biological criteria”, including allowable changes to canopy dominance in each vegetation quadrat as well as for the average over the entire wetland. Significant negative impacts are defined in the permit as a total decline in canopy basal area (dominance) of 20% or more averaged over the entire wetland site or a canopy decline of 40% or more at any individual station.
Overall average canopy basal area (quadrats) as well as groundcover
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Cited by (4)
Tidal coastal wetlands for wastewater management
2023, Advances in Chemical Pollution, Environmental Management and ProtectionCitation Excerpt :And for coastal regions like Louisiana in the U.S., often characterized by degraded water quality caused partly by inadequate sewage treatment, these wetland functions are paramount in addressing the issue.70,74 Although, only in a few cases have scientists (especially in the U.S.) conducted research in coastal wastewater facilities in states like Louisiana,70 North Carolina,75–77 and South Carolina78 and focused on the wastewater management aspect in the practical term. In this regard, most of the works in the U.S. and other countries are computational.
Assessing the risk of utilizing tidal coastal wetlands for wastewater management
2019, Journal of Environmental ManagementCitation Excerpt :Conclusions from this body of literature have indicated that wastewater additions to forested swamps increased foliar turnover (Brantley et al., 2008) and improved diameter growth for trees (Day et al., 2004; Lundberg et al., 2011). Other research efforts have focused on the Carolinas (Knight et al., 2014) but are identified as managed forest plantations (Frederick et al., 1998; Ghezehei et al., 2015) and are similarly limited to aboveground growth (Shifflett et al., 2014). Few studies have evaluated plant productivity for longer than 5 years and tend to focus on a single treatment wetland (Keim et al., 2012; Shaffer et al., 2015).
Research Status and Trends of Taxodium distichum
2023, HortScienceCoastal forests and groundwater: Using case studies to understand the effects of drivers and stressors for resource management
2017, Sustainability (Switzerland)