May 2014

Scott Wilson

USEPA Office of Water

Overview of PEA Authorities 

for Water Associated with Oil 

and Gas Extraction

1
How Can Extraction of Oil and Gas 

Impact Water Resources?

• Concerns about potential impact to surface waters

– For example, shale gas wastewater contains high concentrations of total 

dissolved solids (salts), and may also contain various organic chemicals, 

inorganic chemicals, metals, and naturally occurring radioactive materials 

(NORM)

• Concerns about potential endangerment of water supplies

– If diesel fuels are used, hydraulic fracturing fluids may contain benzene, toluene, 

ethylbenzene or xylene (BTEX) compounds which are highly mobile in ground 

water and are regulated under the national primary drinking water regulations

• Sustainability of water resources

– Water sources used for horizontal hydraulic fracturing often come from public 

water sources, or directly from ground or surface waters

– Recycling flowback/produced water is becoming more common in areas where 

water availability or disposal is limited

2
Federal Water Authorities Applicable 

to Oil and Gas Extraction

Clean Water Act

• National Pollutant Discharge 

Elimination System 

Permitting and National 

Pretreatment Program

• Effluent Limitations 

Guidelines and Standards 

(ELGs)

• Water quality criteria and 

standards

Safe Drinking Water Act

• Underground Injection 

Control Program Class II 

regulations

• Hydraulic fracturing (HF) 

using diesel fuels

• Produced water/flowback 

injection

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The Clean Water Act

• Established the National Pollutant Discharge Elimination 

System (NPDES) permitting program

• Prohibits the discharge of pollutants, unless authorized 

by NPDES permits

• Requires permits to contain limits for:

– Best Available Technology Economically Achievable

• Effluent Limitations Guidelines (ELGs) have been established 

by EPA for most industries

– Water Quality based limits are required when 

technology based limits along aren’t sufficient
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CWA Programs to Control Industrial 

Discharges

POTW

Industry

Industry

National Pretreatment 

Program

(“indirect dischargers”)

National Pollutant Discharge 

Elimination System (NPDES) 

discharge permits

(“direct dischargers”)
NPDES 

permit 

Water QualityBased Effluent 

Limits 

State Water 

Quality 

Standards

Technology-Based 

Standards (Effluent 

Limitation Guidelines)

TechnologyBased 

Effluent Limits

Clean Water Act

For Direct Discharges into Waters of the U.S. 

(e.g., rivers, streams)

Permit by 

local entity 

(POTW)

National PreTreatment 

Standards

Local 

Limits

For Indirect Discharges 

(into sewers)

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Oil and Gas Extraction Effluent 

Limitations Guidelines (ELGs) 40 CFR 

Part 435

– Onshore Subcategory

• No discharge

– Striper Subcategory

• Produces <10 bbl/day oil

• Oil and grease 35 ppm

– Ag and Wildlife 

(western)

• Discharge if of good 

enough quality

– Coastal Subcategory

• No discharge

– Offshore Subcategory

• oil and grease 29/42 ppm
Agriculture and Wildlife Use 

Subcategory

• Discharges are currently 

authorized in some western 

states

– mostly from oil extraction

• States vary on what meets the 

“good enough quality” limits in 

the ELG

• TDS limits vary from 150 ppm to 

10,000 ppm based on cattle 

watering

• Whole effluent toxicity limits 

applied in many cases
Challenges with Current ELGs

• Onshore Subcategory – No pretreatment standards

• Coal Bed Methane – not under Part 435 ELG

- Where no applicable ELG, permit writers must include limits based 

on case-by-case, “best professional judgment” basis.

– EPA began studying the need for an ELG in 2006

– States permit inconsistently using:

• Coal Mining ELGs – Eastern states

• Agriculture and Wildlife Subcategory – Rocky Mountain States

• No discharge – New Mexico, Oklahoma, Texas

• Centralized Waste Treatment Facilities

– Current regulations at Part 437 do not include pertinent limits

• Subcategories: Metals, Oils, Organics, and Mixed Wastes

• Example: Oil and Grease limits are 38 ppm avg./127 ppm max.
Revisions to Oil and Gas Extraction 

ELGs

• In Fall, 2011, EPA announced it was initiating a rulemaking to 

develop pretreatment standards for shale gas extraction discharges 

under the existing oil and gas ELGs

– POTWs are not equipped to treat all pollutants in unconventional O&G 

wastewater

– EPA plans to propose new standards for public comment in Fall 2014

• In Fall, 2011, EPA announced it was initiating a rulemaking to 

develop ELGs for coalbed methane extraction discharges

– Based on review of information collected to date EPA proposed to 

discontinue this portion of the rulemaking (August 2013)

• EPA may not be able to identify a nationally applicable treatment technology 

that would be economically achievable

• A final determination will be made considering public comments

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Water Quality Criteria Issues

• Many states have not adopted dissolved solids or 

chloride water quality criteria

– Ionic components vary significantly by source

• Produced water - chlorides

• Coal Mines - bicarbonate and sulfate

– Currently revising recommended chloride criteria 

• Starting peer review process in 2014

– Conductivity has been suggested as a surrogate

• Inexpensive and easy to measure

• Not as effective as addressing specific ions

– Developing methods to address bromide in 

discharges to better protect drinking water 

(trihalomethane)
Safe Drinking Water Act

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Safe Drinking Water Act 

Authorities

• EPA’s central authority to protect drinking water is from 

the Safe Drinking Water Act (SDWA) 

• SDWA requires EPA to set legal limits on the levels of 

certain contaminants in drinking water 

• SDWA also requires EPA to protect underground sources 

of drinking water (USDWs) from contamination caused by 

underground injection

• SDWA §1431 contains provisions to address imminent 

and substantial endangerment

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Potential Fluid Migration 

Pathways

1. Faulty injection well casing

2. Annulus between casing 

and the well bore

3. Migration through confining 

layers from injection zone

4. Vertical migration through 

improperly abandoned and 

completed wells

5. Lateral migration from 

within injection zone into a 

protected portion of USDW

6. Direct injection of fluids into 

or above a USDW

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Abandoned Well

Confining Layer

Injection Zone

Injected Fluid

Confining Layer

USDW

1

2

3

4

5

6

USDW

UIC: Prevent Endangerment of 

USDWs
• EPA UIC Program established six classes of wells 

(Classes I – VI)

• Class II wells inject fluids associated with oil and natural 

gas extraction including:

– Fluids brought to the surface in connection with natural gas 

storage operations, or oil or natural gas extraction (e.g., 

produced water) Class II-D

– For enhanced recovery of oil or natural gas (e.g., well 

stimulation) Class II-ER

– For the storage liquid hydrocarbons (usually as part of the US 

Strategic Petroleum Reserve) Class II-S

• UIC programs may not unnecessarily interfere with or 

impede oil and gas production activities

SDWA Underground Injection Control 

Program

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UIC Well Classification

Well Class Function Inventory

Class I Hazardous industrial and 

municipal wastes

650

Class II Fluids related to oil and 

gas production

168,000

Class III Solution mining (e.g. salt, 

uranium)

21,400

Class IV Shallow hazardous waste –

only used for remediation 

activities

24 sites

Class V Shallow injection of 

nonhazardous fluids

500,000 – 650,000

(Estimate – precise 

inventory is unknown)

Class VI Geologic sequestration of 

carbon dioxide

N/A

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Class II Well Requirements

Injection of oil and gas production fluids

Key Protective Requirements:

Construction and Siting

 Cased and cemented to prevent movement of 

fluids into underground sources of drinking 

water

 Construction and design of well (casing, 

tubing, and packer) varies

Monitoring and Testing

 Internal and external mechanical integrity test

 Periodic monitoring and reporting

Recordkeeping and Reporting

 Plan for safe plugging and abandoning of 

wells 17
Energy Policy Act 2005

• SDWA: Congress revisited SDWA definition of 

“underground injection” and exempted hydraulic 

fracturing except when diesel fuel is used(section 

1421(d)(1)(B)):

– (i) the underground injection of natural gas for purposes of 

storage; and 

– (ii) the underground injection of fluids or propping agents (other 

than diesel fuels) pursuant to hydraulic fracturing operations 

related to oil, gas, or geothermal production activities.

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Guidance on HF with Diesel 

Fuels

• Published the Permitting Guidance for Oil and Gas Hydraulic 

Fracturing Activities Using Diesel in February 2014. 

• Outlines for EPA permit writers, where EPA is permitting authority:

– Requirements for diesel fuels used for hydraulic fracturing wells, 

– Technical recommendations for permitting those wells, and 

– A description of diesel fuels.

• Recommendations built on best practices from industry and state oil 

and gas programs.

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HF Guidance (Cont’d)

• Description of Diesel Fuels:

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Five CAS Numbers:

Diesel Fuel / 

Diesel Fuel 

No. 1 

(68334-30-5)

Diesel Fuel / 

Diesel Fuel 

No. 2 

(68476-30-2)

Fuel Oil No. 2 

/ Diesel Fuel

(68476-34-6)

Fuel Oil No. 4 

/ Diesel Fuel 

No. 4

(68476-31-3)

Kerosene / 

Marine Diesel 

Fuel

(8008-20-6)
EPA Website: 

http://water.epa.gov/type/groundwater/uic/index.cfm

Code of Federal Regulations: Underground Injection Control

Regulations 40 CFR 144-148: 

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?sid=d6ee71a544eca89c533c825135913f13&c=ecfr&tp

l=/ecfrbrowse/Title40/40cfrv22_02.tpl

More Information about the 

UIC Program

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