1. A systems level perspective on Marcellus wastewater management in Pennsylvania LESLIE ABRAHAMS Engineering and Public Policy Civil and Environmental Engineering labrahams@cmu.edu

2. Between 4-5 million gallons of water are used to hydraulically fracture a well 2 https://www.epa.gov/hfstudy/hydraulic-fracturing-water-cycle

3. The Marcellus Shale formation is not located in a water stressed region 3 Vengosh, Avner, et al. (2014)

4. Wastewater volume varies by geology, hydrocarbon, and extraction method 4 Across the US, over 20 billion bbls were generated in 2012 from all oil and gas operations, projected to increase to over 34 billion by 2025 In the Marcellus, we estimate 40 thousand bbls per well of produced water  > 60% within the first two years  > 2 M bbls over lifetime of the play

5. Marcellus wastewater is unique from other wastewater due to its high salinity Flowback WaterProduced Water Flow rateHighLow (10-50 bbl/day) DurationFirst ten days (up to 3 weeks)Life of the well TDS< 200,000 ppm> 300,000 ppm T=0 Flow Rate T=30 Days Post Fracturing Salinity 300,000 ppm 20,000 ppm 150,000 gpd 15,000 gpd Flowback Produced 5

6. The optimal wastewater management strategy varies across the play Decision is driven by the produced water quality, location of the well, source water cost, and treatment costs Reuse has been common in PA, but it is a temporary solution Treated at CWTs Disposed of in Class II injection wells Treated on-site 6

7. We can compare management strategies using Monte Carlo analysis Wastewater Parameters Volume Quality (TDS) Treatment Parameters Cost ($/bbl) Quality (TDS) Transportation Parameters Cost ($/bbl) Distance (miles) User Interface User specified data Wastewater Management Decision Support Metrics: 1. Cost 2. GHG Emissions 7

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9. Disposal is likely the least cost option despite injection wells being in OH, WV 9 $5.80 $7.40 $8.40 On average, treatment costs 30% more than disposal The simulation suggests the least cost strategy would be: 62% = Disposal 30% = CWT 8% = On-Site On-site costs likely much higher  No system currently commercially viable  Several regulatory and operational barriers CWT costs rely on sellable byproducts  Dependent on permits and market demand

10. Geospatial dimension is important to inform produced water management policies $6/bbl = 20% of wells$5/bbl = 33% of wells$4.25/bbl = 48% of wells$0/bbl = 58% of wells 10 There are tradeoffs in trucking cost versus treatment cost Assume $0.02/bbl-mile trucking cost, disposal cost of $0.75/bbl

11. Reducing cost beyond $4/bbl does not capture additional wells for treatment 11 Management decision is more sensitive to CWT cost than disposal cost cost

12. Subsidies and investments in new produced water treatment likely ineffective at incentivizing treatment over disposal 12 A new CWT in southwest PA would still require costs to drop below $2/bbl

13. At a CWT cost of $9/bbl, disposal costs would need to be over $3.50/bbl

14. Produced water contain salts, heavy metals, NORMs, halogens, among other contaminants Unauthorized disposal or accidental spills have demonstrated widespread death/distress of aquatic species and mortality to ground vegetation – In PA, inadequately treated wastewater discharged into surface waters contained high levels of salinity, toxic metals, radioactive elements, and organic constituents High bromide levels resulted in a spike in downstream disinfection byproducts in municipal drinking water Led to a 2010 ban on disposal of shale gas water to POTWs and CWTs Even if treated to MCLs, there are risks associated with discharging wastewater – Over time, metals, salts, NORMS, and organics may build up in sediments – Physiochemical conditions of surface waters and properties of the compound will determine how it interacts with the sediment – Reactive constituents would be absorbed into the soil and pose long- term environmental and public health risks 14

15. Class II injection wells are regulated by the EPA under the Safe Drinking Water Act >30,000 permitted Class II wells in the US Induced seismic activity is the largest risk from disposal Historical evidence from regions with extensive oil and gas development suggests disposal is a low risk strategy The central and eastern U.S. have experienced an increase in earthquake rates since 2009. The largest of these was a magnitude 5.6 earthquake in central Oklahoma that destroyed 14 houses and injured two people Research suggests seismicity is induced by high disposal rates and can be successfully managed through pressure monitoring and reduced rates Experiment in Oklahoma; plan to reduce rates by more than 300 kbd over 2015 average rates Class II injection wells also pose potential risks, but likely can be managed 15

16. Produced water is a small volume, yet costly water quality issue in PA Other large scale water quality issues include Acid-Mine Drainage (AMD) and agricultural runoff – Less contaminated; less costly to remediate/mitigate via lime neutralization and vegetative buffer strips, respectively 16 $5.80 $7.40 $8.40 $0.05 $0.08 For differential between disposal and CWT of $2/bbl, PA could address: –60 years of AMD –All 655 thousand acres of cropland with high runoff potential, 560 thousand acres of critically under treated cropland, and 324 thousand acres of cropland adjacent to surface waters in the Susquahanna river basin These options would mitigate existing risk rather than introducing new water quality issues into surface waters $2/bbl translates to $0.005/Mcf for producers Avg. WTP = $1.5/bbl

17. PA should consider natural gas produced water management from a systems level perspective Disposal is likely the least cost produced water management strategy throughout the state – Few additional wells could be incentivized to treat water if costs were decreased from $4-$2/bbl – Treating produced water is energy intensive, results in increased emissions over disposal Risk of induced seismic activity is believed to be manageable through monitoring and reduced disposal rates – Releasing treated surface waters may pose long term risk of contaminant bio-accumulation in sediments PA can integrate effective wastewater management with improved water quality objectives throughout the state – Capture a portion of differential between disposal and CWT to address AMD and agricultural runoff, two primary water quality issues across PA 17