2011 Ground Water Summit and 2011 Ground Water Protection Council Spring Meeting

The Potential for Anthropogenic Contamination of Groundwater In a Bedrock Aquifer Having Variable Overburden Cover In a Semi-Urban Setting

Wednesday, May 4, 2011: 3:10 p.m.
Baltimore (Hyatt Regency Baltimore on the Inner Harbor)
John C. Kozuskanich, The Johnson Company;
Kent S. Novakowski, Ph.D., Queen's University;
Bruce C. Anderson, PhD, Queen's University;

This study examines how anthropogenic contaminant sources in a semi-urban setting, where both septic systems and agriculture are present, might be impacting groundwater quality in an underlying bedrock aquifer having variable overburden cover.  A research site was developed in a lakeside village where Paleozoic sediments and Precambrian metasediments and igneous intrusives are overlain by a discontinuous sandy till.  Eight monitoring wells were installed, hydraulically tested and completed as multilevel piezometers.  A monitoring and sampling program, including water levels, precipitation, nutrients, chloride, fecal indicator bacteria, δ2H and δ18O of water, and 40 pharmaceuticals and personal care products (PPCPs), was employed.  The results show variability in the response of multilevel piezometer water levels to recharge events and local residential pumping.  Multiple septic systems, agricultural runoff, and road salt application in areas with thin or inadequate overburden are identified as groundwater pollution sources.  Vertical connectivity in the fracture network is thought to be limited, but is sufficient enough to allow surface contaminants to migrate relatively quickly and deeply into the bedrock aquifer.  Dilution from recharge, heterogeneity in the flow system, and variability in the pollution source input results in the inconsistent spatiotemporal distribution of contaminant concentrations.  PPCPs provide an interpretation on the type and number of sources that could not otherwise be established using traditional methods including nutrient concentrations and fecal indicator bacteria.  Fecal indicator bacteria provide a consistent and cost-effective method for determining the potential for adverse public health impacts due to groundwater consumption in this setting because drinking water standards have been established.