The data from this study indicate that the OWTS at sites 1 and 2 contributed significantly to concentrations of fecal indicators in shallow groundwater.
OWTS at both sites contributed to elevated concentrations of E.
Concentrations of both fecal indicators exceeded these surface water contact standards in groundwater from both the drainfield and piezometers downgradient from the OWTS.
perfringens concentrations in the surficial aquifer decreased with closer proximity to the estuary, however with no apparent influence by the OWTS.
While both Bacteroides HF183 and HumM2 markers were detected in septic tank wastewater, the HF183 marker was detected more often in groundwater samples, suggesting that it may be a more reliable marker to use as a source tracking tool related to OWTS.
Background piezometers were upgradient from the OWTS, but background groundwater quality could have been influenced by other human and animal waste sources in the neighborhood, such as other OWTSs and animals.
North Carolina requires a separation distance of 45 cm from OWTS trenches to seasonal high water table.