Biogeochemistry of Groundwater beneath On-site Wastewater Systems in a Coastal Watershed

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Biogeochemistry of Groundwater beneath On-site Wastewater Systems in a Coastal Watershed

Journal Title: Universal Journal of Environmental Research and Technology - Year 2011, Vol 1, Issue 3

Abstract

The goal of this study was to determine if on-site wastewater system PO4 and coliform contributions to groundwater were significant enough to be included in water quality management plans for a coastal watershed. Monitoring wells were installed adjacent to 16 on-site systems in three different soil types (sand, sandy loam and sandy clay loam) in Carteret County, North Carolina. Groundwater beneath on-site wastewater systems was collected and analyzed for coliform bacteria and PO4 and compared to septic effluent and background groundwater. Physical and chemical properties of groundwater including pH, electrical conductivity, and temperature were measured monthly for over 1 year (January 2007-February 2008). Data indicated that mean groundwater pH, PO4, coliform and electrical conductivity beneath on-site systems were typically elevated relative to background groundwater. Groundwater beneath on-site wastewater systems in sandy clay loam soils had the lowest mean PO4 and lowest median coliform concentrations (0.04 ± 0.03 mg/L and 1.02 x 104 cfu/100 mL). On-site systems in sand had the highest mean groundwater PO4 concentrations (2.46 ± 2.9 mg/L) and systems in sandy loam had the highest median groundwater coliform concentrations (2.21 x 104 cfu/100 mL). On-site wastewater systems in watersheds with sandy soils (> 77% sand and < 24% clay) can contribute significant concentrations of PO4 and coliform to groundwater and these contributions should be included in watershed management strategies for improving water quality.

Authors and Affiliations

Humphrey C. P. and O'Driscoll M. A.

Keywords

EP ID EP31656
DOI -
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