Hydraulic fracturing is necessary for development of the Marcellus shale natural gas as this process opens up fractures in the shale which allow the natural gas to flow to the well. This operation involves injecting several
million gallons of water, sand, and a small addition of chemical additives into the formation at high pressure. After the injection is completed, approximately 10-20 percent of the fluids (known as flowback) return to the surface via the well. Therefore, a 5-million gallon hydraulic fracture stimulation might return 500,000 to 1 million gallons of water. The reuse of the flowback fluids by the drilling industry for subsequent hydraulic fracture treatments significantly reduces the volume of wastewater being generated by hydraulic fracturing. This water can be treated and blended with fresh water and reused, which is what many companies are now doing to minimize the amount of water that would otherwise be potentially discharged to streams or rivers once treated.
Currently, new Pennsylvania Department of Environmental Protection standards dictate that any flowback must be treated to have a total dissolved solids (TDS) concentration of 500 parts per million, which is consistent with Pennsylvania drinking water standards, and therefore won't increase TDS levels to unacceptable levels. There are new treatment plants being built to meet these standards and at least one is now in operation in Williamsport, PA.