Nitrogen Treatment Efficiency of a Large Onsite Wastewater System in Relation to Water Table Dynamics

• DOI: 10.1002/clen.201700551
• Publication Date: 2017-11-08T12:42:41Z
• Authors: Charles P. Humphrey; Guy Iverson; Michael O'Driscoll
• Keywords: Piezometer; Elevation (ballistics)

The objective of this study is to determine if the nitrogen treatment efficiency a large onsite wastewater system (OSW) in coastal plain North Carolina influenced by changes elevation water table. Groundwater readings including depth water, pH, temperature, specific conductance, and dissolved oxygen are recorded eight times over 15‐month period (May 2013–August 2014) encompassing typically “wet” (two sampling events) “dry” (three seasons, table fluctuation 1.7 m. from piezometers ( n = 7) near OSW septic tank effluent samples collected for analyses total (TDN) during each field visit TDN elevation. directly correlated with strength (r 0.882; p 0.004) inversely −0.754; 0.031). at site decreases increases elevation, groundwater concentrations beneath higher when higher. Sea level rise climate change projected increase levels therefore may have negative effects on quality adjacent OSW. Ensuring that installed maximum practical vertical separation setback distances surface waters, designed long trenches oriented perpendicular dominant flow direction will help maximize treatment.