District Attorneys go to Court to Block Flow of Contaminated Drilling Leachate to Treatment Plant

Two Western Pennsylvania district attorneys in May took the unusual step of going to court to block a Westmoreland County landfill from sending water contaminated with gas drilling waste to a nearby treatment plant.

The contaminated water, known as leachate, from the Westmoreland Sanitary Landfill, is primarily precipitation that soaks through the landfill contents, picking up contamination. It is collected and piped to the Belle Vernon Municipal Authority’s treatment plant, and then discharged into the Monongahela River, which is a source of drinking water for residents in four counties.

The municipal authority in spring 2018 began to see levels of pollution in its discharge rise, and determined that the contamination was coming from the landfill, where cuttings from gas well drilling were accepted. Cuttings, finely ground pieces of rock, can contain radioactive elements that are naturally occurring, according to the EPA, as well as other chemicals and pollutants used in the drilling process.

The municipal authority determined that the landfill was sending more than double the amount of leachate allowed to the treatment plant, which according to court documents was contaminated with diesel fuel, phenols, possible carcinogens and other chemicals used in gas drilling and fracking.

The leachate was damaging the biological sewage treatment process and resulting in poorly treated water being discharged into the Mon River. The municipal authority decided to stop accepting the leachate, although the state Department of Environmental Protection had urged it to continue over concerns about continuity of service and even proposed an arrangement for the landfill to pay any fines. According to court documents, the volume of leachate rendered the plant’s treatment ineffective and it was acting “simply as a pass-through” for the contaminated water being discharged into the Mon River.

The district attorneys of Fayette County, where the municipal authority is located, and Washington County, which has numerous communities that get their water from the river, then stepped in and a judge issued an injunction temporarily halting the flow.

The landfill company, which had an ineffective pre-treatment system but is building a more advanced system to improve the leachate quality, has agreed to send its wastewater elsewhere for treatment.

While leachate can occur in groundwater from a number of sources, including coal ash piles and coal mines, it is particularly problematic for the landfill industry, which is where most waste, some it hazardous, is buried. Leachate consists of both dissolved and suspended solids that are picked up by water passing through waste material.

Landfills are required to have liners or membranes to protect groundwater, and the leachate is collected in pipes running under the waste. There are many methods for treating leachate, the most common being activated sludge, which is a suspended-growth process that uses aerobic microorganisms to biodegrade organic contaminants in the leachate, an article in Science Direct states. With conventional activated sludge treatment, the leachate is aerated in an open tank with diffusers or mechanical aerators. Leachate can also undergo physiochemical treatment or carbon absorption.

There is much research underway to develop more advanced methods for leachate treatment, particularly for hazardous chemicals and pollutants from gas well drilling. Municipal officials need to be attuned to the amount of leachate being accepted into their disposal systems, and must be certain that their treatment process can meet the needs of the material accepted.

The district attorneys who sought the injunction have also referred the matter to the Pennsylvania attorney general’s office to investigate whether any criminal conduct occurred, and it has now taken over the case.