Gas development in the Marcellus shale, the low-density rock formation underlying portions of the Delaware River Basin in Pennsylvania and New York, is increasing rapidly. Although development has remained outside the Delaware River Basin, the Delaware River Basin Commission (DRBC) began monitoring area rivers in 2010 to measure baseline water quality in anticipation of future gas development.
Hydraulic fracturing creates salty flow back water containing potentially toxic and carcinogenic chemicals. When drills reach target formations, water and chemicals are injected into layers of shale to release natural gas. Wastewater is typically recycled or stored at the well site.
Hydraulic fracturing is a controversial issue and therefore comprehensive monitoring is key to better understanding its environmental responses. Drilling in the Delaware River Basin area will not begin until regulations are approved.
DRBC's new monitoring program is analyzing parameters typically affected by gas development, such as specific conductivity. The water electricity conductivity levels can indicate river contamination. For example, in August 2009 West Virginia's Department of Natural Resources alerted EPA's field office in West Virginia of high-conductivity levels in Dunkard Creek. During the next month about 22,000 fish washed ashore. Eventually nearly every aquatic species along a 35-mile stretch of the waterway was lost in Dunkard Creek, possibly due to nearby hydraulic fracturing.
DRBC has deployed HOBO® U24 conductivity and temperature loggers in the Delaware and Lackawaxen rivers and in two more creeks in Pennsylvania where drilling is likely to take place first. The loggers were chosen primarily for their ability to withstand harsh weather conditions - deployment sites are affected by cold temperature and periodic high flows - and the speed with which they could be deployed.
DRBC Standards & Assessment Section staff constructed low profile concrete bases for their logger installation by pouring concrete into a saucer sled. Two short aluminum pipes jut out from the concrete base. A horizontal PVC pipe with holes lies affixed to the base to house the sensor. The sensor is secured inside the PVC with zip ties. The placement of the sensor within the PVC pipe minimizes bubbles and sediment that might otherwise accumulate on the sensors' faces.
Before deploying the loggers, DRBC staff tested the loggers' accuracy against other meters, measuring a variety of low and high conductivity waters, such as ultra-pure lab water, tap water, and salt water. The staff found agreement between the meters. Staff periodically retrieves the loggers and downloads readings with a data shuttle.
"The HOBO Waterproof Shuttle's optical interface allows us to easily download data in the field," said John Yagecic, Environmental Engineer and Section Supervisor at DRBC. Then staff cleans the loggers with distilled water and redeploys them.
Since deploying the loggers in January 2011, they have performed reliably while tolerating harsh weather conditions and branches and other objects moving downstream.
"The loggers have proved to be an inexpensive solution for high-risk deployment," Yagecic said.
By defining the range and variability of specific conductivity measurements before gas development occurs, this monitoring program will help DRBC protect water resources in the Delaware Basin.