1 / 29

Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed

Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed. NYWEA Watershed Science and Technical Conference September 15, 2009 ▪ West Point. Grantley Pyke, P.E. – Hazen and Sawyer Frank Getchell, L.H.G. – Leggette, Brashears, & Graham Kimberlee Kane, Ph.D. – NYCDEP.

loring
Download Presentation

Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed NYWEA Watershed Science and Technical Conference September 15, 2009 ▪ West Point Grantley Pyke, P.E. – Hazen and SawyerFrank Getchell, L.H.G. – Leggette, Brashears, & GrahamKimberlee Kane, Ph.D. – NYCDEP

  2. Agenda • Natural Gas Production and the Marcellus Shale • Hydrogeologic Background and Conceptual Model • Fracturing Chemicals • Gas Development Activities, Impacts, and Case Studies

  3. Natural Gas and the Marcellus Shale • Marcellus Shale covers ~95,000 mi2; potentially more than 500 tcf of gas reserves • Formation underlies the entire NYC WOH watershed • Northeastern PA and southern NYpotentially one of the most productive parts of the formation • Active leasing in NY, active drilling in PA • 100 gas wells drilled in the last 2 years in Bradford County

  4. Hydraulic Fracturing • Hydraulic fracturing: injecting water at high pressure into a gas-bearing formation to induce fractures & increase permeability • Horizontal wells used to increase the area of the formation fractured • Process requires several million gallons of water per fracture operation; wells may be fractured multiple times during their useful life • Resulting wastewater requires specialized treatment due to high TDS, chemicals, and other contaminants

  5. Agenda • Natural Gas Production and the Marcellus Shale • Hydrogeologic Background and Conceptual Model • Fracturing Chemicals • Gas Development Activities, Impacts, and Case Studies

  6. 6 Hydrogeologic Background and Conceptual Model • Water Flow Regime Characterization Based on: • Hydrogeologic Setting • Ground water recharge and discharge • Ground water and surface water interaction

  7. Hydrogeologic Background and Conceptual Model Study Area Flow Systems Available data Regional, intermediate, and local flow of ground water Interaction of ground water flow systems with surface water Surface water chemistry Water quality “signatures” Ground Water Quality Surface Water Quality 7

  8. Hydrogeologic Background and Conceptual Model

  9. Hydrogeologic Background and Conceptual Model

  10. Hydrogeologic Background and Conceptual Model

  11. Hydrogeologic Background and Conceptual Model

  12. Hydrogeologic Background and Conceptual Model • Freshwater aquifers tend to be developed within ~400 feet of the surface • Deeper aquifers tend to be low quality (e.g., highly mineralized (TDS), saline, etc.) • Surface waters are predominantly influenced by precipitation and runoff under high-flow and average conditions • Surface waters consist predominantly of groundwater discharge (baseflow) during low-flow and drought

  13. Hydrogeologic Background and Conceptual Model 13

  14. Hydrogeologic Background and Conceptual Model Respective chemistries of groundwater and surface water are consistent and can potentially be tracked to determine influences from natural gas development 14

  15. Potential Flow Regime Disruption Mechanisms

  16. Agenda • Natural Gas Production and the Marcellus Shale • Hydrogeologic Background and Conceptual Model • Fracturing Chemicals • Gas Development Activities, Impacts, and Case Studies

  17. Drilling / Fracturing Chemicals Drilling fluid (mud) is typically a mixture of bentonite clay, water, and other chemicals Lubricants, surfactants, defoamers, detergents, polymers, emulsifiers, shale stabilizers, dispersants/deflocculants, flocculants, etc. Fracturing fluid is typically a mixture of water, proppant, acid and chemicals Surfactants, biocides, scale control, iron inhibitors, cross-linkers, gels, friction reducers, etc. ~99% water and sand 17

  18. 18 Fracturing Chemicals • Database developed by The Endocrine Disruptor Exchange • Over 430 products; ~30 functional categories (gellant, stabilizer, surfactant, etc.) • Over 350 individual constituents; ~35 chemical classes (acid, polymer, aldehyde, etc.) • Known composition for products ranges from 0% to 100% • Available information from MSDS, tier II reports, toxicology data, etc. • Little detailed knowledge of products, composition, and usage

  19. Agenda • Natural Gas Production and the Marcellus Shale • Hydrogeologic Background and Conceptual Model • Fracturing Chemicals • Gas Development Activities, Impacts, and Case Studies

  20. Natural Gas Activities, Impacts and Case Studies: Categories of Activities Natural gas development activities grouped into the following categories: • Well Development • Water Consumption • Wastewater / Chemical Management • Long-term and Cumulative Impacts

  21. US Shale Gas Plays

  22. A. Well Development • Activities: drill pad, access road, and pipeline construction, well drilling, and fracturing • Impacts: land disturbance and erosion, subsurface failures • Subsurface failures are unpredictable; associated with operator error or unexpected subsurface conditions • Regulations currently exist for sediment and erosion control in the watershed • Potential impacts would depend on rate and extent of drilling operations; potential monitoring and enforcement challenges

  23. Well Development Case Studies • Garfield Co., CO • In 2004, failed well casing led to BTEX contamination of groundwater and local creek • Contamination was contained and is being mitigated • Dimock, PA • In 2009 methane migrated to the surface at several locations resulting in one explosion • PADEP is investigating and has required well drillers to install gas detectors, supplemental ventilation, and supply bottled water to nearby residents

  24. B. Water Consumption • Activities: procurement of surface or ground water for drilling and hydraulic fracturing • Impacts: Reduced stream flows, aquifer drawdown • Example: PADEP has investigated streams being drained for natural gas production in watersheds outside of SRBC and DRBC jurisdictions

  25. C. Waste / Chemical Management • Activities: transportation, storage, treatment, disposal, and spill mgmt • Impacts: Water contamination from spills and improper waste management • Over 1000 cases of contaminated surface & ground water in the states reviewed • Failed wastewater pits a major factor; leaking liner/no liner and embankment collapse primary failure modes • CO, NM and Fort Worth, TX revised oil and gas drilling regulations in 2008 due to problems with waste management / pollution • Concerns over lack of treatment / disposal capacity (WWTPs, injection wells) in the Marcellus shale region

  26. Waste Management Case Study Monongahela River, PA • Fall 2008, Monongahela River exceeded TDS limits by nearly twice the allowable limit and nearly five times average levels • Initial problems were taste and odor in drinking water, excessive scale on industrial boilers, and high particulates in power plant emissions • Problem was due to high TDS wastewater deliveries to municipal WWTPs from natural gas wells, in addition to unseasonably low stream flow • PADEP required curtailment of high TDS deliveries until natural stream flow increased • Subsequent testing revealed high levels of brominated DBPs at water treatment plants downstream of WWTPs

  27. Waste Management Case Study Underground Injection Well, TX • In 1997 local residents alleged groundwater contamination due to a nearby oil and gas waste injection well site in Panola County, Texas • Contaminants in resident’s wells included benzene, arsenic, lead, and mercury • Texas regulators did not confirm contamination until 2003 and the facility remained operational until 2004 • EPA took responsibility in 2006 and indicated the shallow groundwater contamination was caused by illegal dumping, surface spills, and spillover from the oil and gas waste injection well facility

  28. D. Long-term and Cumulative Impacts Long-term activities include site restoration, long-term maintenance, brine disposal, re-fracking, well plugging • Difficult to reestablish vegetation on severely compacted sites • Drilling pads and access roads may remain open for years • Wells can continue to produce brine water during the life of the well (approximately 10 to 20 years) • Impacts from re-fracking similar to original fracking Cumulative impacts depend on numerous factors • Pace and magnitude of development • Regulatory requirements • No comprehensive studies on the probability or extent fracturing fluid migration / fractures impacting adjacent formations • No long-term experience (greater than ~5-10 yr)

  29. Summary • Water Quality • All activities have the potential to impact water quality; highest risk from erosion, chemical/waste spills, subsurface failures, and ultimate waste disposal • Risk increases as the magnitude of exploration and development increases • Water Quantity • Groundwater flow regimes could be altered by natural gas development, potentially impacting baseflow • Impacts would depend on location, timing, source, and magnitude of withdrawals

More Related