Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed NYWEA Watershed Science and Technical Conference September 15, 2009 ▪ West

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

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

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Agenda

• Natural Gas Production and the Marcellus Shale

• Hydrogeologic Background and Conceptual Model

• Fracturing Chemicals

• Gas Development Activities, Impacts, and Case Studies

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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 NY potentially 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

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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

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Agenda





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Hydrogeologic Background and Conceptual Model

• Water Flow Regime Characterization Based on: Hydrogeologic Setting Ground water recharge and discharge Ground water and surface water interaction

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• 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

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• 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

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Respective chemistries of groundwater and surface water are consistent and can potentially be tracked to determine influences from natural gas development

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Potential Flow Regime Disruption Mechanisms

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Agenda





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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

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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

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Agenda





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Natural Gas Activities, Impacts and Case Studies: Categories of Activities

Natural gas development activities grouped into the following categories:

A. Well Development

B. Water Consumption

C. Wastewater / Chemical Management

D. Long-term and Cumulative Impacts

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US Shale Gas Plays

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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

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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

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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

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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

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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

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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

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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)

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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

Documents

Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed NYWEA Watershed Science and Technical Conference September 15, 2009 ▪ West