Recent technological advancements have made it possible to produce natural gas from deep shale reservoirs in the State of Ohio. The first, known as the Marcellus Shale, is one of the largest deposits of natural gas in the United States. The Marcellus Shale reservoir is estimated to contain enough gas to meet the entire energy demand in the United States for the next few decades. Marcellus Shale natural gas wells already have been drilled in the southeastern Ohio counties of Jefferson, Belmont, Monroe, Noble, Washington and Athens. Additional development is anticipated in Carroll, Columbiana, Mahoning, Harrison and Guernsey counties.
Located below the Marcellus is the Utica Shale, which is rich in both natural gas and liquid hydrocarbons. The Utica Shale reservoir stretches across significant portions of eastern and central Ohio, with small pockets in northwestern Ohio. Utica Shale wells have been drilled in Muskingum, Fairfield, Hocking, Hancock and Henry counties, among others. Additional development in Delaware, Wayne, Stark, Tuscarawas, Mahoning, Carroll, Harrison, Jefferson, Guernsey, Belmont, and other Ohio counties is expected in 2011.
The process used to reach the deep shale reservoirs involves two important steps: (1) horizontal drilling; and (2) hydraulic fracturing. Production in a deep shale reservoir generally involves both vertical and horizontal drilling. A well is initially drilled vertically into an area close to the shale reservoir and then gradually angled horizontally through the shale reservoir. The horizontal drilling process allows for maximum capture of natural gas and other hydrocarbons from the shale reservoirs.
Hydraulic fracturing is the process of injecting a highly pressurized mixture of water, sand and chemicals into shale formations to expand them and stimulate gas production. Because the fracing fluid is primarily comprised of water, enormous volumes of water are required for the fracing of a single Marcellus or Utica Shale well. In fact, there are estimates that a single well going through the hydraulic fracturing process will use approximately four (4) million gallons of water.
Due to the high internal pressures within the Marcellus and Utica Shale formations, significant amounts of “flowback” or “fracing” fluid are discharged from each well. Approximately 15–20% of the injection fluid returns to the surface within 7–10 days of being pumped into the well. Carrying with it minerals (e.g. calcium and sulfur), suspended solids, soluble salts and low-levels of naturally occurring radioactive elements (e.g. radium). The end product is a low-salinity wastewater solution that must be properly disposed of by the producer.
Treatment of Flowback from Marcellus and Utica Shale Wells
The low salinity flowback wastewater produced during the fracing process is generally transported off-site for either injection into a Class II underground injection control well (regulated by the Ohio Department of Natural Resources (ODNR)), or treatment at a public wastewater treatment facility (regulated in part by Ohio EPA). Although the ODNR and the Ohio EPA appear to favor disposal of the flowback wastewater through injection in Class II wells, the alternative option of treatment at a public wastewater treatment facility represents a potentially significant revenue producer for local governments.
Ohio EPA and the Treatment of Flowback Wastewater
The Marcellus Shale boom in Pennsylvania has provided Ohio regulators with some guidance in terms of how to deal with the low-salinity flowback from Marcellus and Utica Shale wells in Ohio. Citing concerns over high total dissolved solids in Pennsylvania’s Monongahela River as a result of discharges from Marcellus Shale oil and gas wells, the Ohio EPA has been hesitant to issue National Pollutant Discharge Elimination System NPDES permits to Ohio wastewater facilities seeking to accept and treat such discharges.
In particular, the Ohio EPA is concerned with the impact to Ohio waterways if the low-salinity wastewater is treated and then discharged into them. The concern stems from the Ohio EPA’s belief that a typical wastewater treatment facility cannot treat all of pollutants in the flowback water (specifically total dissolved solids consisting of chlorides, sodium and sulfates), and would rely on dilution of the low-salinity wastewater. It is for this reason that Ohio regulators are encouraging disposal through injection in Class II underground injection control wells.
It is clear, however, that the use of Class II wells will not be the sole method for disposal of the flowback wastewater. The Ohio EPA will examine the treatment of low-salinity flowback at public wastewater treatment plants on a case-by-case basis as long as: (1) the flowback water contains 50,000 mg/L or less of total dissolved solids; (2) the wastewater treatment facility applies for a modification to its NPDES permit, including proposed limits for total dissolved solids, chlorides, and possibly other pollutants such as sulfates, sulfides, benzene, toxic organic chemicals and radium and uranium isotopes; and (3) in some circumstances, meets certain other regulatory requirements such as:
- Requiring wastewater treatment facilities to determine the total dissolved solids concentration causing toxicity as determined through biomonitoring testing for whole effluent toxicity.
- Conducting periodic biological surveys upstream and downstream of the wastewater facility to determine the impact on the aquatic biological community.
- Determining whether compliance with the anti-degradation rule will be necessary based upon the Ohio EPA’s position that the low-salinity flowback is considered to be an industrial discharge. The applicability of the anti-degradation rule would require certain information to be submitted to the Ohio EPA, including downstream water quality impacts and impacts to facility operations.
- Submission of a request to modify the local government’s “sewer use ordinance,” if a community has an Ohio EPA approved pretreatment program, to include additional local limits for pollutants associated with the low-salinity discharge and determine if biological systems in the unit processes will be inhibited.
- Submission of a permit-to-install (PTI) application if the facility plans to install or modify any wastewater collection or treatment equipment needed to accept the low-salinity discharge. Additional monitoring may also be required as a part of a PTI approval.
The City of Warren’s Modification to its (NPDES) Permit
The Ohio EPA recently issued an NPDES permit modification (NPDES 3PE00008*MD), effective December 1, 2010, to the City of Warren allowing its wastewater treatment plant to accept 100,000 gallons per day (gpd) of flowback water. Viewing the 100,000 gpd limit in the NPDES as too restrictive, the City of Warren filed an appeal with the Environmental Review Appeals Commission (ERAC No. 786501).
The City’s basis for the appeal is that the Ohio EPA had “no reasonable technical basis nor lawful justification” to set such a restrictive limit on the quantity of flowback water discharged from the wastewater treatment plant, while also pointing out that the restriction does not appear in law or in the permits of other municipal dischargers. Furthermore, the City is claiming that the Ohio EPA used “inaccurate, outdated and inappropriate data” to set the discharge limit and also set the limit based on “hypothetical, outdated, future, speculative scenarios, including possible ‘future load increases’ and ‘future changes to Ohio water quality standards.’”