MGS geologists presented talks at the 2017 Maryland Groundwater Symposium, September 28, 2017
Using a Well Camera to Assess the Integrity of Maryland’s Long-Term Water-Level Monitoring Wells
Maryland Geological Survey (MGS), along with the United States Geological Survey and Maryland Department of the Environment, collects water-level and water-quality data from a network of approximately 475 monitoring wells across the state. Data from these wells are critical in assessing the condition of the aquifers (gauging available drawdown) and in water-supply planning (calibrating groundwater-flow models). The average age of the wells is 35 years, though many date back to the mid-1900’s or even earlier and are now showing signs of age. MGS has recently acquired a well camera to help assess the health of this monitoring well network.
A well camera with portable recording unit can be a useful tool to assess the health and integrity of monitoring wells. Problems such as breaks in the casing, casing corrosion, encrusted screen openings, bacterial accumulation, and debris blockages can all be seen in vivid color to inform exactly what needs to be done to rehabilitate a well. Periodic well camera surveys can be an important part of a comprehensive preventative maintenance or well management program. This session will present examples of common problems found during well camera surveys and will discuss the challenge of maintaining a large and aging well network.
Well Water Quality in the Appalachian Plateau Physiographic Province of Maryland
Well water contamination related to the development of the Marcellus Shale natural gas reserves in Pennsylvania and elsewhere has underscored the need for a baseline evaluation of well water-quality data prior to natural gas development. In Maryland, water-quality data was obtained from more than 2,300 wells in the Appalachian Plateau Physiographic Province of Maryland (which includes all of Garrett County and the western portion of Allegany County), and was evaluated with respect to drinking-water standards, geologic unit, land use, topographic position, and other factors. Data sources included the Garrett County and Allegany County Health Departments, the Maryland Department of the Environment, the Maryland Geological Survey (part of the Maryland Department of Natural Resources), and the U.S. Geological Survey. Major ions, trace elements, radionuclides, nutrients, and other constituents were evaluated with respect to geologic unit, land use, topographic position (upland or valley), and other factors.
Well water in the study area tended to be near neutral, moderately hard, low in dissolved oxygen (reducing conditions), and low in dissolved solids. Arsenic concentrations exceeded the Maximum Contaminant Level (MCL) of 0.010 milligrams per liter (mg/L) in about 7% of wells sampled. Approximately 22% of samples collected in the Hampshire Formation exceeded the MCL. Iron concentrations exceeded the Secondary MCL (SMCL) of 0.3 mg/L in approximately 57% of wells sampled. The highest percentage of iron exceedances was observed in the Allegheny Formation (88%) and the lowest was from the Hampshire Formation (37%). Manganese concentrations exceeded the SMCL of 0.050 mg/L in approximately 54% of wells sampled. The highest percentage of manganese exceedances was observed in the Allegheny Formation (96%) and the lowest was from the Hampshire Formation (52%). Chloride concentrations exceeded the SMCL of 250 mg/L in approximately 2% of wells. Most elevated chlorides were likely associated with road salt or other surfacebased sources, but several wells have characteristics of diluted brines. Nitrate concentrations were relatively low throughout the Appalachian Plateau, which is likely due to reducing groundwater conditions, where ammonium is the dominant nitrate ion. Methane concentrations tended to be low (less than 10 percent were greater than 1 mg/L); concentrations were higher in valleys than hilltops or hillsides and higher in coal-bearing areas than non-coal areas. Land use was not determined to have a significant effect on groundwater compared to other areas of Maryland.
For a the full set of abstracts presented at the symposium, visit: