GROUND WATER AND PUBLIC HEALTH: A NEW SHALLOW WELL TECHNOLOGY TO PROVIDE SAFE DRINKING WATER FOR PRIVATE WELLS

In northern New England, about 40 percent of the population uses private domestic groundwater wells. These wells draw primarily from bedrock aquifers where high concentrations of naturally-occurring arsenic are common. In contrast, water in shallow glacial deposits that commonly overlie bedrock typically produce water with little or no naturally occurring arsenic. They exhibit groundwater geochemical conditions that inhibit arsenic solubility. However, these glacial aquifers have been under-utilized in the last few decades due to outdated and unsanitary dug well technology. A low-maintenance shallow well design recently patented by the USGS could eliminate many of the concerns associated with the use of shallow, low-permeability aquifers and could provide safe drinking water to a large fraction of the New England population that would otherwise rely on arsenic-contaminated bedrock wells. The USGS well design comprises a single vertical riser with a sanitary well cap and pitless adapter. It also includes horizontal collectors that extend outward from the bottom of the riser within a trench that is backfilled with crushed stone. The length of the horizontal collectors, and therefore the approximate length of the trench, is determined by the hydraulic conductivity of the aquifer material and the depth of the trench relative to static groundwater levels. A geotextile fabric and native fill material overly the crushed stone in the trench to prevent surface contaminants from reaching the well. In 2017, the USGS, the University of New Hampshire, the Maine Geological Survey, and U.S. Environmental Protection Agency launched a new project to install and test the well design at two pilot sites in northern New England. Monitoring is underway for yield and water quality 6 times per year. Preliminary results indicate that yields and water levels are favorable. Water chemistry and microbiological data will be presented in this talk.