U.S. Environmental Protection Agency 

Documentation of OMB Review Under Executive Order 12866 

Title of Action: 

Docket#: FRL#: RIN:

This action was submitted to the Office of Management and Budget (OMB) for review under Executive Order (E.O.) 

12866, titled Regulatory Planning and Review (58 FR 51735, October 4, 1993). Whenever EPA makes publicly available 

a regulatory action that was reviewed under E.O. 12866, section 6(a)(3)(E) of the E.O. directs the Agency to also: 

(1) Make available to the public a copy of the information that was provided to OMB’s Office of Information and 

Regulatory Affairs (OIRA) for review under the E.O., i.e., the text of the draft regulatory action and, if applicable, 

an assessment of the potential costs and benefits, as well as additional information for those actions that are 

determined to be economically significant under the E.O. (Information requirements are described in sections 

6(a)(3)(B) and (C)). 

(2) Identify for the public any substantive changes between the draft submitted to OIRA and the action that was 

subsequently issued, using a method that is complete, clear, and simple. 

(3) Identify for the public those substantive changes made at the suggestion or recommendation of OIRA.

For this regulatory action, were substantive changes made to information reviewed under E.O. 

12866? [Please check the appropriate answer.]

No. [In the docket, include the information identified in item (1) below.]

Yes. [In the docket, include the information identified in items (1) – (3) below.]

Accordingly, the Agency has included this form and the following information in the public 

docket for this regulatory action: [Please check the appropriate information.]

(1) A copy of the information that was provided to OIRA for review under the E.O. 

(2) Documentation of any substantive changes made to the draft regulatory text that was 

submitted to OIRA when compared with what was subsequently made publicly available.

The documentation is provided on the pages following this form. Changes made at the 

suggestion or recommendation of OIRA, if any, are clearly identified through attribution to 

OIRA. EPA has used one or more of the following methods to note changes: [Select the 

appropriate option(s).]

(a) Redline-Strikeout – A copy of the draft regulatory action submitted, using redlinestrikeout to show the substantive changes that were made.

(b) Hand Markup – A copy of the draft regulatory action submitted, using handwritten notes 

to show the substantive changes that were made.

(c) Note to the file - A document that identifies the substantive changes that were made, 

with page and paragraph references to the draft regulatory action that was submitted.

If you have any questions about this regulatory action or this documentation, please call the 

contact:

Name: Email: Phone: 

Revised 05/05/2010 

Effluent Limitations Guidelines and Standards for the Oil and Gas Extraction Point Source Category

EPA-HQ-OW-2014-0598 FRL-9917-78-OW 2040-AF35

Lisa Biddle biddle.lisa@epa.gov 202-566-0350
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EO12866_OilandGasEffluentGuidelinesandStandards RIN 2040-AF35 NPRM FRN_20141015 

 6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Part 435

[EPA-HQ-OW-2014-0598; FRL-9917-78-OW]

RIN 2040-AF35

Effluent Limitations Guidelines and Standards for the Oil and Gas Extraction Point 

Source Category 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The EPA proposes a Clean Water Act regulation that would better protect 

public health and the environment and protect the operational integrity of publicly owned 

treatment works (POTWs) by establishing pretreatment standards that would prevent the 

discharge of pollutants in wastewater from onshore unconventional oil and gas extraction 

facilities to publicly owned treatment works. Unconventional oil and gas (UOG) 

extraction wastewater may be generated in large quantities and contains constituents that 

are potentially harmful to human health and the environment. Because they are not 

typical of POTW influent wastewater, some UOG extraction wastewater constituents 

may be discharged, untreated, from the POTW to the receiving stream; may disrupt the 

operation of the POTW (e.g., by inhibiting biological treatment); may accumulate in 

biosolids (sewage sludge), limiting its use; and may facilitate the formation of harmful 

disinfection by-products. Because the requirements in this proposal reflect current 

industry practice for unconventional oil and gas extraction facilities, the EPA does not 
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project the proposed rule will impose any costs or lead to pollutant removals, but will 

ensure that such current industry best practice is maintained over time. 

DATES: Comments on this proposed rule must be received on or before [insert date 60 

days after publication in the Federal Register]. The EPA will conduct a public hearing 

on the proposed pretreatment standards on XXX[INSERT DATE] at XXX[INSERT 

TIME] in the EPA East Building, Room 1153, 1201 Constitution Avenue, NW, 

Washington, DC. 

ADDRESSES: Submit your comments on the proposed rule, identified by Docket No. 

EPA-HQ-OW-2014-0598 by one of the following methods: 

 http:www.regulations.gov: Follow the on-line instructions for submitting 

comments. 

 Email: OW-Docket@epa.gov, Attention Docket ID No. EPA-HQ-OW-2014-

0598. 

 Mail: Water Docket, U.S. Environmental Protection Agency, Mail code: 4203M, 

1200 Pennsylvania Ave., NW., Washington, DC 20460. Attention Docket ID No. EPAHQ-OW-2014-0598. Please include three copies. 

 Hand Delivery: Water Docket, EPA Docket Center, EPA West Building Room 

3334, 1301 Constitution Ave., NW, Washington, DC, Attention Docket ID No. EPA-HQOW-2014-0598. Such deliveries are only accepted during the Docket’s normal hours of 

operation, and you should make special arrangements for deliveries of boxed information 

by calling 202-566-2426. 
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Instructions: Direct your comments to Docket No. EPA-HQ-OW-2014-0598. The 

EPA's policy is that all comments received will be included in the public docket without 

change and may be made available online at http://www.regulations.gov, including any 

personal information provided, unless the comment includes information claimed to be 

Confidential Business Information (CBI) or other information whose disclosure is 

restricted by statute. Do not submit information that you consider to be CBI or otherwise 

protected through http://www.regulations.gov or email. The http://www.regulations.gov 

website is an “anonymous access” system, which means the EPA will not know your 

identity or contact information unless you provide it in the body of your comment. If you 

send an email comment directly to the EPA without going through 

http://www.regulations.gov your email address will be automatically captured and 

included as part of the comment that is placed in the public docket and made available on 

the Internet. If you submit an electronic comment, the EPA recommends that you include 

your name and other contact information in the body of your comment and with any disk 

or CD-ROM you submit. If the EPA cannot read your comment due to technical 

difficulties and cannot contact you for clarification, the EPA may not be able to consider 

your comment. Electronic files should avoid the use of special characters, any form of 

encryption, and be free of any defects or viruses. 

Docket: All documents in the docket are listed in the http://www.regulations.gov 

index. A detailed record index, organized by subject, is available on the EPA’s website at 

http://water.epa.gov/scitech/wastetech/guide/steam_index.cfm. Although listed in the 

index, some information is not publicly available, e.g., CBI or other information whose 

disclosure is restricted by statute. Certain other material, such as copyrighted material, 
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will be publicly available only in hard copy. Publicly available docket materials are 

available either electronically in http://www.regulations.gov or in hard copy at the Water 

Docket in the EPA Docket Center, EPA/DC, EPA West, Room 3334, 1301 Constitution 

Ave., NW, Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 

p.m., Monday through Friday, excluding legal holidays. The telephone number for the 

Public Reading Room is 202-566-1744, and the telephone number for the Water Docket 

is 202-566-2426. 

Pretreatment Hearing Information: The EPA will conduct a public hearing on the 

proposed pretreatment standards on XXX[INSERT DATE] at XXX[INSERT TIME] in 

the EPA East Building, Room 1153, 1201 Constitution Avenue, NW, Washington, DC. 

No registration is required for this public hearing. During the hearing, the public will 

have an opportunity to provide oral comment to the EPA on the proposed pretreatment 

standards. The EPA will not address any issues raised during the hearing at that time but 

these comments will be included in the public record for the rule. For security reasons, 

we request that you bring photo identification with you to the meeting. Also, if you let us 

know in advance of your plans to attend, it will expedite the process of signing in. 

Seating will be provided on a first-come, first-served basis. Please note that parking is 

very limited in downtown Washington, and use of public transit is recommended. The 

EPA Headquarters complex is located near the Federal Triangle Metro station. Upon 

exiting the Metro station, walk east to 12th Street. On 12th Street, walk south to 

Constitution Avenue. At the corner, turn right onto Constitution Avenue and proceed to 

the EPA East Building entrance. 
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FOR FURTHER INFORMATION CONTACT: For technical information, contact 

Lisa Biddle, Engineering and Analysis Division, Telephone: 202-566-0350; email: 

biddle.lisa@epa.gov. For economic information, contact Karen Milam, Engineering and 

Analysis Division, Telephone: 202-566-9752; email: milam.karen@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Regulated Entities 

II. How to Submit Comments 

III. Supporting Documentation 

IV. Overview 

V. Legal Authority 

VI. Purpose and Summary of Proposed Rule 

A. Purpose of the Regulatory Action 

B. Summary of the Proposed Rule 

C. Summary of Costs and Benefits 

VII. Background 

A. Clean Water Act 

B. Effluent Limitations Guidelines and Standards Program 

1. Best Practicable Control Technology Currently Available (BPT) 

2. Best Conventional Pollutant Control Technology (BCT) 

3. Best Available Technology Economically Achievable (BAT) 

4. Best Available Demonstrated Control Technology (BADCT)/New Source 

Performance Standards (NSPS) 

5. Pretreatment Standards for Existing Sources (PSES) and Pretreatment Standards 

for New Sources (PSNS) 

C. Oil and Gas Extraction Effluent Guidelines Rulemaking History 

1. Subpart C: Onshore 

2. Subpart E: Agricultural and Wildlife Use 

D. State Pretreatment Requirements that Apply to UOG Extraction Wastewater 

E. Related Federal Requirements in the Safe Drinking Water Act 

VIII. Summary of Data Collection 
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A. Site Visits 

B. Meetings with Stakeholder Organizations 

1. Stakeholder Organizations 

2. State Stakeholders 

C. Secondary Data Sources 

D. Drilling Info Desktop® Data Set 

E. The EPA Hydraulic Fracturing Study 

IX. Description of the Oil and Gas Industry 

A. Economic Profile 

B. Industry Structure and Economic Performance 

C. Financial Performance 

X. Scope 

XI. Unconventional Oil and Gas Extraction: Resources, Process, and Wastewater 

A. Unconventional Oil and Gas Extraction Resources 

B. Unconventional Oil and Gas Extraction Process 

1. Well Drilling 

2. Well Completion 

3. Production 

C. UOG Extraction Wastewater 

1. Drilling Wastewater 

2. Produced Water 

D. UOG Extraction Wastewater Characteristics 

1. TDS and TDS-Contributing Ions 

2. Organic Constituents 

3. Radioactive Constituents 

E. Wastewater Management and Disposal Practices 

1. Injection into Disposal Wells 

2. Reuse in Fracturing 

3. Transfer to Centralized Waste Treatment Facilities 

4. Transfer to POTWs 

XII. Subcategorization 

XIII. Proposed Regulation 

A. Discussion of Options 

1. PSES and PSNS Option Selection 

2. Other Options Considered 
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B. Pollutants of Concern 

C. POTW Pass Through Analysis 

XIV. Environmental Impacts 

A. Pollutants 

B. Impacts from the Discharge of Pollutants Found in UOG Extraction Wastewater 

C. Impact on Surface Water Designated Uses 

1. Drinking Water Uses 

2. Aquatic Life Support Uses 

3. Livestock Watering Uses 

4. Irrigation Uses 

5. Industrial Uses 

XV. Non-Water Quality Environmental Impacts Associated with the Proposed Rule 

XVI. Implementation 

A. Implementation Deadline 

B. Upset and Bypass Provisions 

C. Variances and Modifications 

XVII. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045: Protection of Children from Environmental Health and 

Safety Risks 

H. Executive Order 13211: Energy Effects 

I. National Technology Transfer Advancement Act 

J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations 

I. Regulated Entities 

 Entities potentially regulated by this proposed action include: 
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Category Examples of Regulated 

Entities 

North American 

Industry Classification 

System (NAICS) Code 

Industry Crude Petroleum and Natural 

Gas Extraction 

211111 

Natural Gas Liquid Extraction 211112 

This section is not intended to be exhaustive, but rather provides a guide for 

readers regarding entities likely to be regulated by this proposed action. Other types of 

entities that do not meet the above criteria could also be regulated. To determine whether 

your facility would be regulated by this proposed action, you should carefully examine 

the applicability criteria listed in 40 CFR 435.30 and the definitions in 40 CFR 435.33(b) 

of the proposed rule and detailed further in Section X – Scope, of this preamble. If you 

still have questions regarding the proposed applicability of this action to a particular 

entity, consult the person listed for technical information in the preceding FOR 

FURTHER INFORMATION CONTACT section. 

II. How to Submit Comments 

The public may submit comments in written or electronic form. (See the 

ADDRESSES section above.) Electronic comments must be identified by the Docket No. 

EPA-HQ-OW-2014-0598 and must be submitted as a MS Word, WordPerfect, or ASCII 

text file, avoiding the use of special characters and any form of encryption. The EPA 

requests that any graphics included in electronic comments also be provided in hard-copy 

form. The EPA also will accept comments and data on disks in the aforementioned file 

formats. Electronic comments received on this notice may be filed online at many Federal 

Depository Libraries. No confidential business information (CBI) should be sent by 

email. 
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III. Supporting Documentation 

The proposed rule is supported by a number of documents including the Technical 

Development Document for Proposed Pretreatment Standards for Unconventional Oil 

and Gas Extraction in the Onshore Oil and Gas Subcategory (TDD), Document No. EPAXXX-X-XX-XXX (DCN SGE00704). This and other supporting documents are available 

in the public record for this proposed rule and on EPA’s website at 

http://water.epa.gov/scitech/wastetech/guide/oilandgas/unconv.cfm. 

IV. Overview 

This preamble describes the reasons for the proposed rule; the legal authority for 

the proposed rule; a summary of the options considered for the proposal; background 

information, including terms, acronyms, and abbreviations used in this document; and the 

technical and economic methodologies used by the Agency to develop the proposed rule. 

In addition, this preamble also solicits comment and data from the public. 

V. Legal Authority 

The EPA proposes this regulation under the authorities of sections 101, 301, 304, 

306, 307, 308, and 501 of the Clean Water Act (CWA), 33 U.S.C. 1251, 1311, 1314, 

1316, 1317, 1318, 1324, and 1361. 

VI. Purpose and Summary of Proposed Rule 

A. Purpose of the Regulatory Action 

Responsible development of America’s oil and gas resources offers important 

economic, energy security, and environmental benefits. The EPA is working with states 

and other stakeholders to understand and address potential impacts of hydraulic 
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fracturing so the public has confidence that oil and natural gas production will proceed in 

a safe and responsible manner. The EPA is moving forward with several initiatives to 

provide regulatory clarity with respect to existing laws and using existing authorities 

where appropriate to enhance public health and environmental safeguards. This proposed 

rule would fill a gap in existing federal wastewater regulations to ensure that the current 

practice of not sending wastewater discharges from this sector to publicly owned 

treatment works continues into the future. 

 Recent advances in the well completion process, combining hydraulic fracturing 

and horizontal drilling, have made extraction of oil and natural gas from low 

permeability, low porosity geologic formations (referred to hereafter as unconventional 

oil and gas (UOG) resources) more technologically and economically feasible than it had 

been. For example, in 2010, U.S natural gas production reached its highest level in more 

than 30 years with much of the increase resulting from the production of natural gas from 

shale formations. The U.S. Department of Energy projects natural gas production in the 

U.S. will likely increase by 44 percent by 2040, compared to 2011 production levels 

(DCN SGE00487). Hydraulic fracturing is used to extract oil and natural gas from highly 

impermeable rock formations, such as shale rock, by injecting fracturing fluids at high 

pressures to create a network of fissures in the rock formations and give the oil and/or 

natural gas a pathway to travel to the well for extraction. Pressure within the low 

permeability, low porosity geologic formations forces wastewaters, as well as oil and/or 

gas, to the surface. In this proposed rulemaking, oil and gas extraction includes 

production, field exploration, drilling, well completion, and/or well treatment; wastewater 
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sources associated with these activities in low permeability, low porosity formations are 

collectively referred to as UOG extraction wastewater. 

Direct discharges of oil and gas extraction wastewater pollutants from onshore oil 

and gas resources, including UOG resources, have been regulated since 1979 under the 

existing Oil and Gas Effluent Limitations Guidelines and Standards (ELGs) (40 CFR part 

435), the majority of which fall under subpart C, the Onshore Subcategory. The 

limitations for direct dischargers in the Onshore Subcategory represent Best Practicable 

Control Technology Currently Available (BPT). Based on the availability and economic 

practicability of underground injection technologies, the BPT-based limitations for direct 

dischargers require zero discharge of pollutants to waters of the United States. However, 

there are currently no requirements in subpart C that apply to onshore oil and gas 

extraction facilities that are “indirect dischargers,” i.e., those that send their discharges to 

publicly owned treatment works (municipal wastewater treatment facilities) known as 

“POTWs.” 

UOG extraction wastewater may be generated in large quantities and contains 

constituents that are potentially harmful to human health and the environment. 

Wastewater from UOG wells often contains high concentrations of total dissolved solids 

(TDS) (salt content). The wastewater may also contain various organic chemicals, 

inorganic chemicals, metals, and naturally-occurring radioactive materials (referred to as 

technologically enhanced naturally occurring radioactive material or TENORM)1

. This 

 

1

 Naturally occurring radioactive materials that have been concentrated or exposed to the accessible 

environment as a result of human activities such as manufacturing, mineral extraction, or water processing 

is referred to as technologically enhanced naturally occurring radioactive material (TENORM). 

“Technologically enhanced” means that the radiological, physical, and chemical properties of the 
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potentially harmful wastewater creates a need for appropriate wastewater management 

infrastructure and management practices. Historically, operators primarily managed their 

wastewater via underground injection (where available). Where UOG wells were drilled 

in areas with limited underground injection wells, and/or there was a lack of wastewater 

management alternatives, it became more common for operators to look to public and 

private wastewater treatment facilities to manage their wastewater. 

POTWs collect wastewater from homes, commercial buildings, and industrial 

facilities and pipe it to a central treatment plant. In some cases, industrial dischargers may 

haul wastewater to the treatment plant by tanker truck. The industrial wastewater, 

commingled with domestic wastewater, is treated by the POTW and discharged to a 

receiving waterbody. However, most POTWs are designed primarily to treat municipally 

generated, not industrial, wastewater. They typically provide at least secondary level 

treatment and, thus, are designed to remove suspended solids and organic material using 

biological treatment. As mentioned previously, wastewater from UOG extraction may 

contain high concentrations of TDS, radioactive elements, metals, chlorides, sulfates, and 

other dissolved inorganic constituents that POTWs are not designed to remove. Because 

they are not typical of POTW influent wastewater, some UOG extraction wastewater 

constituents can be discharged, untreated, from the POTW to the receiving stream; can 

disrupt the operation of the POTW (e.g., by inhibiting biological treatment); can 

accumulate in biosolids (sewage sludge), limiting its use; and can facilitate the formation 

of harmful disinfection by-products. 

 

radioactive material have been altered by having been processed, or beneficiated, or disturbed in a way that 

increases the potential for human and/or environmental exposures. (See EPA 402-r-08-005-v2) 
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Under section 307(b) of the Clean Water Act (CWA), there are general and 

specific prohibitions on the discharge to POTWs of pollutants in specified circumstances 

in order to prevent “pass through” or “interference.” Pass through is defined as whenever 

the introduction of pollutants from a user will result in a discharge that causes or 

contributes to a violation of any requirement of the POTW permit. See 40 CFR 

403.3(p). Interference means a discharge that, among other things, inhibits or disrupts the 

POTW or prevents biosolids use consistent with the POTW’s chosen method of disposal. 

See 40 CFR 403.3(k). These general and specific prohibitions must be implemented 

through local limits established by POTWs in certain cases. See 40 CFR 

403.5(c). POTWs with approved pretreatment programs must develop and enforce local 

limits to implement the general prohibitions on user discharges that pass through or 

interfere with the POTW or discharges to the POTW prohibited under the specific 

prohibitions in 40 CFR 403.5(b). In the case of POTWs not required to develop a 

pretreatment program, the POTWs must develop local limits where there is interference 

or pass through and the limits are necessary to ensure compliance with the POTW’s 

NPDES permit or biosolids use. 

Under section 307(b) of the CWA, the EPA is authorized to establish nationally 

applicable pretreatment standards for industrial categories that discharge indirectly (i.e., 

requirements for an industrial discharge category that sends its wastewater to any POTW) 

for pollutants not susceptible to treatment by POTWs or for pollutants that would 

interfere with the operation of POTWs. Generally, the EPA designs nationally applicable 

pretreatment standards for categories of industry (also referred to as categorical 

pretreatment standards) to ensure that wastewaters from direct and indirect industrial 
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dischargers would be subject to similar levels of treatment. The EPA, in its discretion 

under section 304(g) of the Act, periodically evaluates indirect dischargers not subject to 

categorical pretreatment standards to identify potential candidates for new pretreatment 

standards. To date, the EPA has not established nationally applicable pretreatment 

standards for the onshore oil and gas extraction point source subcategory. 

To legally discharge wastewater, the POTW must have an NPDES permit that 

limits the type and quantity of pollutants that it may discharge. Discharges from POTWs 

are subject to the secondary treatment effluent limitations at 40 CFR part 133, which 

address certain conventional pollutants but do not address the main parameters of concern 

in UOG extraction wastewater (e.g., TDS, chloride, radionuclides, etc.). POTWs are also 

subject to water quality-based effluent limitations (WQBELs) where necessary to protect 

state water quality standards, as required under CWA section 301(b)(1)(C). 

It is currently uncommon for POTWs to establish local limits for some of the 

parameters of concern identified for this proposed rulemaking. This is due to a number of 

factors, including lack of sufficient information regarding pollutants in the wastewater 

being sent to POTWs; lack of national water quality recommendations for key pollutants, 

such as TDS, and lack of state water quality criteria for such key pollutants in some 

states, all of which can create significant informational hurdles to including appropriate 

WQBELs in POTW permits. Where a POTW’s permit does not contain a WQBEL for all 

of the constituents of concern in the wastewater being sent to POTWs, it is difficult to 

demonstrate pass through of industrial pollutants (because “pass through” here means 

making the POTW exceed its permit limits), and thus difficult for POTWs to establish 

local limits to implement the general prohibition in the pretreatment regulations. 
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As a result of the gap in federal CWA regulations, increases in onshore oil and 

gas extraction from UOG resources and the related generation of wastewater requiring 

management, concerns over the level of treatment provided by public wastewater 

treatment facilities, as well as potential interference with treatment processes, and 

concerns over water quality and aquatic life impacts that may result from inadequate 

treatment, the EPA proposes technology-based categorical pretreatment standards under 

the CWA for discharges of pollutants into POTWs from existing and new onshore UOG 

extraction facilities in subpart C of 40 CFR part 435. Consistent with existing BPT-based 

requirements for direct dischargers in this subcategory, the EPA proposes pretreatment 

standards for existing and new sources (PSES and PSNS, respectively) that would 

prohibit the indirect discharge of wastewater pollutants associated with onshore UOG 

extraction facilities. Based on the information reviewed as part of this proposed 

rulemaking, this proposal reflects current industry practice. The EPA has not identified 

any existing onshore UOG extraction facilities that currently discharge UOG extraction 

wastewater to POTWs. Because onshore unconventional oil and gas extraction facilities 

have discharged to POTWs in the past, and because the potential remains that some 

facilities may consider discharging to POTWs in the future, the EPA proposes this rule. 

B. Summary of the Proposed Rule 

The EPA proposes pretreatment standards for existing and new sources (PSES 

and PSNS, respectively) that would prohibit the indirect discharge of wastewater 

pollutants associated with onshore UOG extraction facilities. The EPA is defining UOG 

extraction wastewater as sources of pollutants associated with production, field 

exploration, drilling, well completion, or well treatment (e.g., produced water (which 
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includes formation water, injection water, and any chemicals added downhole or during 

the oil/water separation process); drilling muds; drill cuttings; produced sand). Because 

there are no known discharges to POTWs from UOG extraction at the time of this 

proposal, the EPA proposes that PSES and PSNS that would require zero discharge be 

effective as of the effective date of this rule. 

The EPA does not propose pretreatment standards for wastewater pollutants 

associated with conventional oil and gas extraction facilities at this time. EPA proposes 

to reserve such standards to a future rulemaking, if appropriate. 

C. Summary of Costs and Benefits 

Because the UOG extraction industry is not currently managing wastewaters by 

sending them to POTWs, the proposed rule causes no incremental change to current 

industry practice that the EPA measured as compliance costs or monetized benefits. 

Still, the EPA has considered that while states, localities, and POTWs are not 

currently approving these wastewaters for acceptance at POTWs, some POTWs continue 

to receive requests to accept UOG extraction wastewater (DCN SGE00742; DCN 

SGE00743; DCN SGE00762). This proposed rule would provide regulatory certainty 

and would eliminate the burden on POTWs to analyze such requests. It would also 

eliminate the need to develop requirements in states where UOG extraction is not 

currently occurring, but is likely to occur in the future. While the EPA knows there will 

likely be some reduction in state and POTW staff time and resources, the EPA did not 

attempt to estimate, quantitatively, monetary savings associated with the reduced burden 

to states and localities that would result from this proposed rule. 
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In addition, the EPA predicts that both compliance costs and environmental 

benefits of the proposed rule would be realized in the future if demand returns for 

POTWs to accept UOG extraction wastewaters. Most POTWs are not able to sufficiently 

treat TDS and many other pollutants in UOG extraction wastewater, and thus this 

proposed rule would potentially prevent elevated TDS and the presence of other 

pollutants in POTW effluent. Prevention of the discharge of TDS accomplished by the 

proposed rule would further protect water quality because national water quality criteria 

recommendations have not yet been established for many constituents of TDS. The 

proposed rule could also impose some costs on industry if discharging wastewaters to 

POTWs becomes economically attractive to UOG operations relative to other 

management options in the future. The EPA did not estimate these potential compliance 

costs or environmental benefits because of the uncertainty about future demand for 

POTWs to accept UOG extraction wastewaters and the associated incremental costs or 

benefits. 

VII. Background 

A. Clean Water Act 

Congress passed the Federal Water Pollution Control Act Amendments of 1972, 

also known as the Clean Water Act (CWA), to “restore and maintain the chemical, 

physical, and biological integrity of the Nation’s waters.” 33 U.S.C. 1251(a). The CWA 

establishes a comprehensive program for protecting our nation’s waters. Among its core 

provisions, the CWA prohibits the discharge of pollutants from a point source to waters 

of the U.S., except as authorized under the CWA. Under section 402 of the CWA, 

discharges may be authorized through a National Pollutant Discharge Elimination System 
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(NPDES) permit. The CWA establishes a two-pronged approach for these permits, 

technology-based controls that establish the floor of performance for all dischargers, and 

water quality-based limits where the technology-based limits are insufficient for the 

discharge to meet applicable water quality standards. To serve as the basis for the 

technology-based controls, the CWA authorizes the EPA to establish national 

technology-based effluent limitations guidelines and new source performance standards 

for discharges from different categories of point sources, such as industrial, commercial, 

and public sources, that discharge directly into waters of the United States. 

The CWA also authorizes the EPA to promulgate nationally applicable 

pretreatment standards that restrict pollutant discharges from facilities that discharge 

pollutants indirectly, by sending wastewater to POTWs, as outlined in sections 307(b) 

and (c) and 33 U.S.C. 1317(b) and (c). Specifically, the CWA authorizes that the EPA 

establish pretreatment standards for those pollutants in wastewater from indirect 

dischargers that the EPA determines are not susceptible to treatment by a POTW or 

which would interfere with POTW operations. Pretreatment standards must be 

established to prevent the discharge of any pollutant that may pass through, interfere 

with, or are otherwise incompatible with POTW operations. CWA sections 307(b) and 

(c). The legislative history of the 1977 CWA amendments explains that pretreatment 

standards are technology-based and analogous to BAT effluent limitations for the 

removal of toxic pollutants. As further explained in the legislative history, the 

combination of pretreatment and treatment by the POTW is intended to achieve the level 

of treatment that would be required if the industrial source were making a direct 

discharge. Conf. Rep. No. 95-830, at 87 (1977), reprinted in U.S. Congress. Senate. 
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Committee on Public Works (1978), A Legislative History of the Clean Water Act of 

1977, Serial No. 95-14 at 271 (1978). 

Direct dischargers (i.e., those discharging directly to surface waters) must comply 

with effluent limitations in NPDES permits. Technology-based effluent limitations in 

NPDES permits for direct dischargers are derived from effluent limitations guidelines 

(CWA sections 301 and 304) and new source performance standards (CWA section 306) 

promulgated by the EPA, or based on best professional judgment (BPJ) where the EPA 

has not promulgated an applicable effluent guideline or new source performance standard 

(CWA section 402(a)(1)(B) and 40 CFR 125.3). Additional limitations based on water 

quality standards are also required to be included in the permit where necessary to meet 

water quality standards. CWA section 301(b)(1)(C). The effluent guidelines and new 

source performance standards are established by regulation for categories of industrial 

dischargers and are based on the degree of control that can be achieved using various 

levels of pollution control technology, as specified in the Act. 

The EPA promulgates national effluent guidelines and new source performance 

standards for major industrial categories for three classes of pollutants: (1) Conventional 

pollutants (total suspended solids, oil and grease, biochemical oxygen demand (BOD5), 

fecal coliform, and pH), as outlined in CWA section 304(a)(4) and 40 CFR 401.16; (2) 

toxic pollutants (e.g., metals such as arsenic, mercury, selenium, and chromium; and 

organic pollutants such as benzene, benzo-a-pyrene, phenol, and naphthalene), as 

outlined in section 307(a) of the Act, 40 CFR 401.15 and 40 CFR part 423, appendix A; 

and (3) nonconventional pollutants, which are those pollutants that are not categorized as 

conventional or toxic (e.g., ammonia-N, phosphorus, and total dissolved solids). 
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B. Effluent Limitations Guidelines and Standards Program 

The EPA develops ELGs that are technology-based regulations for specific 

categories of dischargers. The EPA bases these regulations on the performance of control 

and treatment technologies. The legislative history of CWA section 304(b), which is the 

heart of the effluent guidelines program, describes the need to press toward higher levels 

of control through research and development of new processes, modifications, 

replacement of obsolete plants and processes, and other improvements in technology, 

taking into account the cost of controls. Congress has also stated that the EPA need not 

consider water quality impacts on individual water bodies as the guidelines are 

developed; see Statement of Senator Muskie (October 4, 1972), reprinted in U.S. Senate 

Committee on Public Works, Legislative History of the Water Pollution Control Act 

Amendments of 1972, Serial No. 93-1, at 170). 

There are four types of standards applicable to direct dischargers (facilities that 

discharge directly to surface waters), and two types of standards applicable to indirect 

dischargers (facilities that discharge to POTWs), described in detail below. Subsections 1 

through 4 describe standards for direct discharges and subsection 5 describes standards 

for indirect discharges. 

1. Best Practicable Control Technology Currently Available (BPT) 

Traditionally, the EPA defines BPT effluent limitations based on the average of 

the best performances of facilities within the industry, grouped to reflect various ages, 

sizes, processes, or other common characteristics. BPT effluent limitations control 

conventional, toxic, and nonconventional pollutants. In specifying BPT, the EPA looks at 

a number of factors. The EPA first considers the cost of achieving effluent reductions in 
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relation to the effluent reduction benefits. The Agency also considers the age of 

equipment and facilities, the processes employed, engineering aspects of the control 

technologies, any required process changes, non-water quality environmental impacts 

(including energy requirements), and such other factors as the Administrator deems 

appropriate. See CWA section 304(b)(1)(B). If, however, existing performance is 

uniformly inadequate, the EPA may establish limitations based on higher levels of 

control than what is currently in place in an industrial category, when based on an 

Agency determination that the technology is available in another category or subcategory, 

and can be practically applied. 

2. Best Conventional Pollutant Control Technology (BCT) 

The 1977 amendments to the CWA require the EPA to identify additional levels 

of effluent reduction for conventional pollutants associated with BCT technology for 

discharges from existing industrial point sources. In addition to other factors specified in 

section 304(b)(4)(B), the CWA requires that the EPA establish BCT limitations after 

consideration of a two-part “cost reasonableness” test. The EPA explained its 

methodology for the development of BCT limitations in July 9, 1986 (51 Fed. Reg. 

24974). Section 304(a)(4) designates the following as conventional pollutants: BOD5, 

total suspended solids (TSS), fecal coliform, pH, and any additional pollutants defined by 

the Administrator as conventional. The Administrator designated oil and grease as an 

additional conventional pollutant on July 30, 1979 (44 Fed. Reg. 44501; 40 CFR part 

401.16). 
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3. Best Available Technology Economically Achievable (BAT) 

BAT represents the second level of stringency for controlling direct discharge of 

toxic and nonconventional pollutants. In general, BAT-based effluent guidelines and new 

source performance standards represent the best available economically achievable 

performance of facilities in the industrial subcategory or category. Following the 

statutory language, the EPA considers the technological availability and the economic 

achievability in determining what level of control represents BAT. CWA section 

301(b)(2)(A). Other statutory factors that the EPA considers in assessing BAT are the 

cost of achieving BAT effluent reductions, the age of equipment and facilities involved, 

the process employed, potential process changes, and non-water quality environmental 

impacts, including energy requirements and such other factors as the Administrator 

deems appropriate. CWA section 304(b)(2)(B). The Agency retains considerable 

discretion in assigning the weight to be accorded these factors. Weyerhaeuser Co. v. 

Costle, 590 F.2d 1011, 1045 (D.C. Cir. 1978). 

4. Best Available Demonstrated Control Technology (BADCT)/New Source Performance 

Standards (NSPS) 

NSPS reflect effluent reductions that are achievable based on the best available 

demonstrated control technology (BADCT). Owners of new facilities have the 

opportunity to install the best and most efficient production processes and wastewater 

treatment technologies. As a result, NSPS should represent the most stringent controls 

attainable through the application of the BADCT for all pollutants (that is, conventional, 

nonconventional, and toxic pollutants). In establishing NSPS, the EPA is directed to take 
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into consideration the cost of achieving the effluent reduction and any non-water quality 

environmental impacts and energy requirements. CWA section 306(b)(1)(B). 

5. Pretreatment Standards for Existing Sources (PSES) and New Sources (PSNS) 

As discussed above, section 307(b) of the Act calls for the EPA to issue 

pretreatment standards for discharges of pollutants from existing sources to POTWs. 

Section 307(c) of the Act calls for the EPA to promulgate pretreatment standards for new 

sources (PSNS). Both standards are designed to prevent the discharge of pollutants that 

pass through, interfere with, or are otherwise incompatible with the operation of POTWs. 

Categorical pretreatment standards for existing sources are technology-based and are 

analogous to BPT and BAT effluent limitations guidelines, and thus the Agency typically 

considers the same factors in promulgating PSES as it considers in promulgating BAT. 

See Natural Resources Defense Council v. EPA, 790 F.2d 289, 292 (3rd Cir. 1986). 

Similarly, in establishing pretreatment standards for new sources, the Agency typically 

considers the same factors in promulgating PSNS as it considers in promulgating NSPS 

(BADCT). 

C. Oil and Gas Extraction Effluent Guidelines Rulemaking History 

The EPA promulgated the first Oil and Gas Extraction ELGs (40 CFR part 435) in 

1979, and substantially amended the regulation in 1993 (Offshore), 1996 (Coastal), and 

2001 (Synthetic-based drilling fluids). The Oil and Gas Extraction industry is 

subcategorized in 40 CFR part 435 as follows: (1) subpart A: Offshore; (2) subpart C: 

Onshore; (3) subpart D: Coastal; (4) subpart E: Agricultural and Wildlife Water Use; and 

(5) subpart F: Stripper. 
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The existing subpart C regulation covers wastewater discharges from field 

exploration, drilling, production, well treatment, and well completion activities in the oil 

and gas industry. Although unconventional oil and gas resources occur in offshore and 

coastal regions, recent development of UOG resources in the U.S. has occurred primarily 

onshore in regions to which the regulations in subpart C (Onshore) and subpart E 

(Agricultural and Wildlife Water Use) apply and thus, the gap in onshore regulations is 

the focus of this proposed rulemaking effort. For this reason, only the regulations that 

apply to onshore oil and gas extraction are described in more detail here. 

1. Subpart C: Onshore 

Subpart C applies to facilities engaged in the production, field exploration, 

drilling, well completion, and well treatment in the oil and gas extraction industry which 

are located landward of the inner boundary of the territorial seas – and which are not 

included in the definition of other subparts – including subpart D (Coastal). Practically, 

this means land-based facilities that are not located on a water of the U.S. and are inland 

of the boundary that is used to define “coastal” oil and gas facilities at 40 CFR 435.40. 

The regulations at 40 CFR 435.32 specify the following for BPT: there shall be no 

discharge of waste water pollutants into navigable waters from any source associated 

with production, field exploration, drilling, well completion, or well treatment (i.e., 

produced water, drilling muds, drill cuttings, and produced sand). The existing 

regulations do not include national categorical pretreatment standards for discharges to 

POTWs. The existing oil and gas extraction ELGs did not establish requirements that 

would apply to privately-owned wastewater treatment facilities that accept oil and gas 

extraction wastewaters but that are not engaged in production, field exploration, drilling, 
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well completion, or well treatment. Discharges from such facilities are not subject to 40 

CFR part 435, but rather are subject to requirements in 40 CFR part 437, the Centralized 

Waste Treatment Category. 

2. Subpart E: Agricultural and Wildlife Use 

Subpart E applies to onshore facilities located in the continental United States and 

west of the 98th meridian for which the produced water has a use in agriculture or 

wildlife propagation when discharged into navigable waters. Definitions in 40 CFR 

435.51(c) explain that the term “use in agricultural or wildlife propagation” means that 

(1) the produced water is of good enough quality to be used for wildlife or livestock 

watering or other agricultural uses; and (2) the produced water is actually put to such use 

during periods of discharge. The regulations at 40 CFR 435.52 specify that the only 

allowable discharge is produced water, with an oil and grease concentration not 

exceeding 35 mg/L. The BPT regulations prohibit the discharge of waste pollutants into 

navigable waters from any source (other than produced water) associated with 

production, field exploration, drilling, well completion, or well treatment (i.e., drilling 

muds, drill cuttings, produced sands). 

D. State Pretreatment Requirements that Apply to UOG Extraction Wastewater 

In addition to applicable federal requirements, some states regulate the 

management, storage, and disposal of UOG extraction wastewater, including regulations 

concerning pollutant discharges to POTWs from oil and gas extraction facilities. In 

addition to pretreatment requirements, some states have indirectly addressed the issue of 

pollutant discharges to POTWs by limiting the management and disposal options 

available for operators to use. 
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During initial development of Marcellus shale gas resources, some operators 

managed UOG wastewater by transfer to POTWs. The EPA did not identify other areas 

in the United States where POTWs routinely accepted UOG extraction wastewaters. 

Refer to TDD Chapter A.2 which summarizes how Pennsylvania, Ohio, and West 

Virginia responded to UOG extraction wastewater discharges into their POTWs. 

E. Related Federal Requirements in the Safe Drinking Water Act 

As required by the Safe Drinking Water Act section 1421, the EPA has 

promulgated regulations to protect underground sources of drinking water through 

Underground Injection Control (UIC) programs that regulate the injection of fluids 

underground. These regulations are found at 40 CFR parts 144–148, and specifically 

prohibit any underground injection not authorized by UIC permit. 40 CFR 144.11. The 

regulations classify underground injection into six classes; wells that inject fluids brought 

to the surface in connection with oil and gas production are classified as Class II UIC 

wells. Thus, onshore oil and gas extraction facilities that seek to meet the zero discharge 

requirements of the existing ELGs or proposed pretreatment standard through 

underground injection of wastewater must obtain a Class II UIC permit for such disposal. 

VIII. Summary of Data Collection 

In developing the proposed rule, the EPA considered information collected 

through site visits and telephone contacts with UOG facility operators, facilities that treat 

and/or dispose of UOG extraction wastewater, and wastewater management equipment 

vendors. The EPA also collected information through outreach to stakeholders including 

industry organizations, environmental organizations, and state regulators. The EPA 
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conducted an extensive review of published information and participated in industry 

conferences and webinars. The following describes the EPA’s data collection activities 

that support the proposed rule. 

A. Site Visits 

The EPA conducted seven site visits between May, 2012 and September, 2013 to 

UOG extraction companies and UOG extraction wastewater treatment facilities. The 

purpose of these visits was to collect information about facility operations, wastewater 

generation and management practices, and wastewater treatment and reuse. Six of the 

seven visits were to facilities in Pennsylvania, and one was in Arkansas, however, 

information collected often covered operations beyond just those visited during the site 

visits, at times including company operations in many UOG formations across the U.S. In 

addition to site visits, the EPA conducted 11 telephone conferences or meetings with 

UOG operators and facilities that treat and/or dispose of UOG extraction wastewater. The 

EPA collected detailed information from the facilities visited and contacted, such as 

information about the operations associated with wastewater generation, wastewater 

treatment, and reuse. The EPA also contacted 11 vendors of equipment and processes 

used to manage and treat UOG extraction wastewater. The EPA prepared site visit and 

telephone meeting reports, and telephone call reports summarizing the collected 

information. The EPA has included in the public record site visit reports, meeting reports, 

and telephone contact reports that contain all information collected for which facilities 

have not asserted a claim of CBI. 
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B. Meetings with Stakeholder Organizations 

Since announcing initiation of this proposed rulemaking activity, the EPA has 

actively reached out to interested stakeholders to solicit input from well operators, 

industry trade associations, interested regulatory authorities, technology vendors, and 

environmental organizations. Stakeholder involvement in the regulatory development 

process is essential to the success of this effort. The EPA will continue to engage with the 

affected regulated sector and concerned stakeholders throughout the rulemaking process. 

1. Stakeholder Organizations 

In addition to the site visit related activities described above, the EPA participated 

in multiple meetings with industry stakeholders, their representatives, and/or their 

members, including America’s Natural Gas Alliance (ANGA), American Petroleum 

Institute (API) and the Independent Petroleum Association of America (IPAA). The 

purpose of the meetings was to discuss the EPA’s thinking concerning a pretreatment 

standard for the UOG extraction industry, to better understand industry wastewater 

management practices, and to gather information to inform its proposed rulemaking (see 

DCN SGE00967). 

The EPA participated in a conference call with the environmental stakeholder, 

Environmental Defense Fund (EDF). The purpose of this meeting was to explain the 

EPA’s thinking about the standard under development and learn about the perspectives of 

EDF regarding wastewater management in the UOG extraction industry. 

The EPA participated in a two conference calls with the Center for Sustainable 

Shale Development (CSSD), a collaborative group made up of environmental 
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organizations, philanthropic foundations, and energy companies from the Appalachian 

Basin. The purpose of these calls was to learn about the performance standards under 

development by the CSSD for sustainable shale gas development, based on an 

“independent, third-party evaluation process.” 

2. State Stakeholders 

In an effort to improve future implementation of any UOG regulation, the EPA 

initiated an EPA–State implementation pilot project coordinated by the Environmental 

Council of States (ECOS) and the Association of Clean Water Administrators (ACWA) 

to draw on experience of state agency experts. Through this pilot project, the EPA has 

been able to more thoroughly consider the strengths and weaknesses of different 

approaches in order to select one that produces environmental results while more fully 

considering implementation burden. This pilot effort with the states has also been an 

opportunity to hear ideas on how technology innovation can be fostered during both 

development and implementation of the regulation. 

In addition to the state implementation pilot, the EPA also reached out to the EPA 

Regional, as well as state, pretreatment coordinators. One way the EPA did this was by 

participating in calls, where the EPA staff learned about past or present discharges to 

POTWs from UOG operations. See DCN SGE00742; DCN SGE00743. 

C. Secondary Data Sources 

The EPA conducted an extensive search and review of published information 

about UOG development, wastewater generation and management practices, and 

wastewater treatment, disposal, and reuse. Because of the rapid developments in the 
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UOG industry, in addition to reviewing published information, the EPA participated in 

more than 12 industry conferences and webinars between March 2012 and June 2014. 

Presenters at these conferences provided information about current industry wastewater 

management practices. The EPA also obtained information from the EPA Regions and 

states. The EPA Region 3 provided information about the development of the Marcellus 

shale gas industry and disposal of shale gas wastewater, including discharges to POTWs. 

D. Drilling Info Desktop® Data Set 

The EPA used a propriety database of all oil and gas wells in the United States, 

called DI Desktop®, obtained from DrillingInfo. This comprehensive database includes 

information such as well API number, operator name, basin (e.g., Western Gulf), 

formation (e.g., Eagle Ford), well depth, drilling type (i.e., horizontal, directional, 

vertical), spud date, and completion date. It also includes annual oil, gas, and water 

production for each well. The EPA primarily used this database to quantify and identify 

locations of existing UOG wells, quantify wastewater generation rates, and supplement 

geological information (e.g., basin, formation) in other data sources. 

E. The EPA Hydraulic Fracturing Study 

At the request of Congress, the EPA's Office of Research and Development is 

conducting a study to better understand any potential impacts of hydraulic fracturing on 

drinking water resources. The scope of the research includes the full lifecycle of water in 

hydraulic fracturing, including wastewater management and disposal. In support of its 

study, the EPA conducted a series of technical workshops, including, among others, a 

workshop on Wastewater Treatment and Related Modeling. In support of the proposed 

rule, the EPA reviewed information collected in support of the Congressionally-mandated 
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study and attended meetings, workshops, and roundtable discussions pertaining to water 

and wastewater management and treatment in the UOG extraction industry. See DCN 

SGEXXX, DCN SGEXXX [ORD Materials, note: all publicly available except 

FracFocus report which will be published in fall of 2014]. 

IX. Description of the Oil and Gas Industry 

Oil and Gas Extraction is the exploration and production of crude oil and natural 

gas from wells. Refer to Section XI. for additional background of unconventional gas 

resources, extraction processes, and wastewater generation. As explained previously, the 

scope of this proposed rulemaking is limited to pretreatment standards for wastewater 

generated from unconventional, rather than conventional, oil and gas extraction facilities. 

The description here provides a broader description of the oil and gas industry in order to 

provide the context in which the UOG industry lies. 

A. Economic Profile 

The major products of the Oil and Gas Extraction Industry are petroleum, natural 

gas, and natural gas liquids.2

 Domestic consumption of crude oil and petroleum products 

is met by a combination of domestic production and imports. Like oil consumption, 

natural gas consumption is met both by domestic production and imports of natural gas – 

although imports contribute a much lower share of total domestic consumption for natural 

gas than for oil. Domestic consumption of natural gas rose throughout the 1980s and 

1990s due to low prices relative to prices for oil products. This led to investments in 

 

2

 Natural gas can include “natural gas liquids” (NGLs), components that are liquid at ambient temperature 

and pressure. NGLs are hydrocarbons—in the same family of molecules as natural gas and crude oil, 

composed exclusively of carbon and hydrogen. Ethane, propane, butane, isobutane, and pentane are all 

NGLs. 
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infrastructure for natural gas, especially electric generation facilities (DCN SGE00809). 

In 2010, total consumption of natural gas in the United States was about 24 quadrillion 

British thermal units (Btu). Of total consumption, about 22 quadrillion Btu, was delivered 

to consumers – residential, commercial, industrial, vehicle fuel, and electric power. 

Natural gas can be produced both from conventional natural gas deposits and 

unconventional deposits. Natural gas, and especially unconventional natural gas, has 

become increasingly significant to the U.S. energy economy. The rising importance of 

natural gas largely results from its lower air pollution characteristics compared to other 

fossil fuels; its substantial, and increasing, domestic supply; and the presence of a welldeveloped processing and transmission/distribution infrastructure in the U.S. (DCN 

SGE00010). The energy sector has become progressively more reliant on natural gas with 

the electric power sector’s consumption of natural gas increasing by more than 50 percent 

between 1996 and 2005 (DCN SGE00809). In 2009, natural gas accounted for just under 

a quarter (23.4 percent) of total U.S. energy supply and the majority of natural gas was 

from domestic resources. Increased natural gas production from shale formations also has 

the potential to reduce U.S. dependence on energy-related imports. 

Between 2000 and 2012, total marketed production of natural gas in U.S. as a 

whole grew by 25 percent, with an average annual growth rate of 0.8 percent (DCN 

SGE00908). The sharp rise in production of shale gas contributed to a lower price of 

natural gas, thereby increasing the gap between prices of gas and oil, which made oil a 

relatively more attractive option for producers. Beginning in 2005, the disparity between 

oil and natural gas prices started to grow as oil prices continued to rise while natural gas 

prices declined. Many firms that produce both gas and oil began to focus on acquisition 
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of, and production from, liquids-rich formations over natural gas production (DCN 

SGE00817, DCN SGE00832). 

Overall, domestic crude oil production steadily declined between 2000 and 2008, 

while steadily increasing after that. This shift towards liquids production is evident in the 

sharp rise in production from tight oil resources, including shale, beginning in 2008. 

From 2007 to 2013, the Energy Information Administration (EIA) estimated that tight oil 

production increased 10-fold, from 0.34 to 3.48 million barrels per day (DCN 

SGE00902). Future domestic demand for liquid fuels will depend on the future level of 

activities dependent on liquid fuels, such as transportation. Demand will also be affected 

by the fuel efficiency of the consumption technology. The transportation sector will 

continue to account for the largest share of total consumption despite its share of total 

consumption falling due to improvements in vehicle efficiency. The industrial sector is 

the only end-use sector likely to see an increase in consumption of petroleum and liquids 

(DCN SGE00913). 

While oil and natural gas are often considered together, the way in which prices 

are set for each greatly differs. While the price of oil is set at the global level, natural gas 

prices for the United States tend to be set regionally, because of transportation factors. In 

recent years, the ratio of oil prices to natural gas prices has reached historically high 

levels (DCN SGE00547). While these two products have some commonalities in their 

uses, oil and gas are not perfect substitutes as they require different transportation and 

processing infrastructure, and have a number of differentiated uses. 
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The EPA gathered information on the industry via the North American Industry 

Classification System (NAICS), which is a standard created by the U.S. Census for use in 

classifying business establishments within the U.S. economy. The industry category that 

would be affected by this proposed rule is Oil and Gas Extraction Industry (NAICS 

21111). This industry has two subcategories: (1) Crude Petroleum and Natural Gas 

Extraction (NAICS 211111), which is made up of facilities that have wells with 

petroleum or natural gas or produce crude petroleum from surface shale or tar sands, and 

Natural Gas Liquid Extraction (NAICS 211112), which recover liquid hydrocarbons from 

oil and gas field gases and sulfur from natural gas. 

B. Industry Structure and Economic Performance 

According to data from the Statistics of U.S. Businesses (SUSB), in 2011 there 

were 6,528 firms under the overall oil and gas extraction sector. This is a total 2.4 

percent growth since 2000 to 2011 and an average annual growth rate of 0.2 percent. The 

Crude Petroleum and Natural Gas Extraction segment contributed 6,523 (or 99%) firms 

to the total Oil and Gas Extraction sector, and the Natural Gas Liquid Extraction segment 

contributed 136 (less than 1%) firms to the overall sector. Although the Natural Gas 

Liquid Extraction segment is much smaller in numbers compared to the Crude Petroleum 

and Natural Gas Extraction segment, the total percent change from 2000 to 2011 is much 

higher for natural gas liquids extraction at 61.9% as compared to 1.7% for crude 

petroleum and natural gas extraction. If the ratio of oil-to-natural gas prices remains high, 

there may be a shift towards drilling in liquids-rich shale formations, making this sector 

increasingly important to oil and gas extraction firms (DCN SGE00832; DCN 

SGE00807; DCN SGE00817; DCN SGE00921). 
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In 2011, 98.5% of the Oil and Gas Extraction Industry was estimated to be a small 

business when using the Small Business Administration definition of a small business as 

having 500 or fewer employees. Average revenues for firms for the overall oil and gas 

extraction sector in 2007 were estimated at $43 million, a 99% increase from 1997 to 

2007. This is an average revenue of $36 million per firm in the crude petroleum and 

natural gas extraction segment, and average revenue of $333 million per firm in the 

natural gas liquid extraction segment. The oil and gas extraction overall sector has an 

average of 17.9 employees per firm. Breaking it out per segment, the natural gas liquid 

extraction segment has an average of 73.5 employees per firm, whereas the crude 

petroleum and natural gas extraction segment shows an average of 16.7 employees per 

firm. 

The oil market is a globally integrated market with multiple supply sources that 

are connected to multiple markets. Because of the international cartel’s (the Organization 

of Petroleum Exporting Countries’ (OPEC’s)) high accounting of global oil reserves, 

OPEC is able to place producer quotas on members in an effort to manage world oil 

prices. This means crude oil producers, like many U.S. companies, do not exert control 

over the price they receive at the point of production (price-takers). Global oil prices are 

also greatly influenced by global demand for oil, with the largest source of demand being 

the U.S. and China (DCN SGE00854). While the U.S. is one of the largest sources of 

crude oil production, it still is a major importer of oil and, therefore, has an important 

influence over oil prices. The recent upsurge in U.S. oil production, largely from tight 

and shale oil resources, has led to a drop in U.S. imports, which in turn has exerted 

downward pressure on international oil prices. 
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In North America, specifically within the United States, there is a relatively 

mature, integrated natural gas market with a robust spot market for the natural gas 

commodity. Essentially, the spot market is the daily market, where natural gas is bought 

and sold for immediate delivery. For understanding the price of natural gas on a specific 

day, the spot market price is most informative. In U.S. natural gas markets, natural gas 

spot prices are determined by overall supply and demand (DCN SGE00547). 

Large volume consumers of natural gas, mainly individual consumers and 

electricity generators, generally have the ability to switch between oil and natural gas. 

When the price of gas is low relative to oil, these consumers may switch to gas, 

increasing demand for natural gas and increasing gas prices. Alternatively, when gas 

prices are high, demand may shift in the opposite direction causing a relative decrease in 

natural gas prices (DCN SGE00921). 

C. Financial Performance 

The EPA reviewed financial performance of UOG extraction firms and other oil 

and gas firms. The EPA found no deterioration in financial performance and conditions 

for UOG firms over the previous decade, and this suggests that UOG firms are wellpositioned for continued investment in UOG exploration and development. The strong 

growth in revenue and total capital outlays by the UOG firms during the latter part of the 

last decade – which coincides with the growth in UOG exploration and production 

activity – underscores the economic opportunity provided by the emerging UOG resource 

and the industry’s commitment to investing and producing UOG for the foreseeable 

future. See the Industry Profile (DCN SGE00932) for more information. 
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X. Scope 

Through the proposed rule, the EPA is not reopening the regulatory requirements 

applicable to direct dischargers. Rather, the EPA would amend subpart C only to add 

requirements for indirect dischargers where there currently are none: specifically, 

pretreatment standards for facilities engaged in oil and gas extraction from UOG sources

that send their discharges directly to POTWs. For purposes of this proposed rulemaking, 

the EPA proposes to define “unconventional oil and gas (UOG)” as “crude oil and natural 

gas3

 produced by a well drilled into a low porosity, low permeability formation 

(including, but not limited to, shale gas, shale oil, tight gas, tight oil).” As a point of 

clarification, although coalbed methane would fit this definition, the proposed 

pretreatment standards would not apply to pollutant discharges to POTWs associated 

with coalbed methane extraction. The EPA notes that the requirements in the existing 

effluent guidelines for direct dischargers also do not apply to coalbed methane extraction, 

as this industry did not exist at the time that the effluent guidelines were developed and 

was not considered by the Agency in establishing the effluent guidelines (DCN 

SGE00761). To reflect the fact that neither the proposed pretreatment standards nor the 

existing effluent guideline requirements apply to coalbed methane extraction, the EPA is 

expressly reserving a separate unregulated subcategory for coalbed methane in the 

proposed rule. For information on CBM, see 

http://water.epa.gov/scitech/wastetech/guide/oilandgas/unconv.cfm. The remainder of 

 

3

 Natural gas can include “natural gas liquids,” components that are liquid at ambient temperature and 

pressure. 
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the information presented in this document is specific to the UOG resources subject to the 

proposed rule. 

XI. Unconventional Oil and Gas Extraction: Resources, Process, and Wastewater 

A. Unconventional Oil and Gas Extraction Resources 

For purposes of the proposed rule, UOG consists of crude oil and natural gas4

produced by wells drilled into formations with low porosity and low permeability. UOG 

resources include shale oil and gas, resources that were formed, and remain, in low 

permeability shale. UOG resources also include tight oil and gas, resources that were 

formed in a source rock and migrated into a reservoir rock such as sandstone, siltstones, 

or carbonates. The tight oil/gas reservoir rocks have permeability and porosity lower than 

reservoirs of conventional oil and gas resources but with permeability generally greater 

than shale. As described above, while CBM is sometimes referred to as an 

unconventional resource, the proposed rule does not apply to this industry. 

B. Unconventional Oil and Gas Extraction Process 

1. Well Drilling 

Prior to the well development processes described in the following subsections, 

operators conduct exploration and obtain surface use agreements, mineral leases, and 

proper permits. These steps can take a few months to several years to complete. When 

completed, operators construct the well pad and begin the well development process, as 

described in the following subsections. 

 

4

 Natural gas can include “natural gas liquids,” components that are liquid at ambient temperature and 

pressure. 
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Drilling occurs in two phases: exploration and development. Exploration activities 

are those operations involving the drilling of wells to locate hydrocarbon bearing 

formations and to determine the size and production potential of hydrocarbon reserves. 

Development activities involve the drilling of production wells once a hydrocarbon 

reserve has been discovered and delineated. 

Drilling for oil and gas is generally performed by rotary drilling methods, which 

involve the use of a circularly rotating drill bit that grinds through the earth’s crust as it 

descends. Drilling fluids (muds) are injected down through the drill bit via a pipe that is 

connected to the bit, and serve to cool and lubricate the bit during drilling. Drilling fluids 

can be water or synthetic based. Synthetic-based drilling fluids are also referred to as 

non-aqueous drilling fluids. Air is also used in place of water or synthetic based drilling 

fluids for the vertical phase of wells. The rock chips that are generated as the bit drills 

through the earth are termed drill cuttings. The drilling fluid also serves to transport the 

drill cuttings back up to the surface through the space between the drill pipe and the well 

wall (this space is termed the annulus), in addition to controlling downhole pressure. As 

drilling progresses, pipes called “casing” are inserted into the well to line the well wall. 

Drilling continues until the hydrocarbon bearing formations are encountered. 

In UOG resources, the crude oil and natural gas often occur continuously within a 

formation. As a result, UOG drilling often employs “horizontal drilling.” Horizontal 

drilling involves a sequence of drilling steps: (1) vertical (described above) and (2) 

horizontal. In horizontal drilling, operators drill vertically down to a desired depth, about 

500 feet above the target formation (called the “kickoff point”), and then gradually turn 

the drill approximately 90 degrees to continue drilling laterally continuously through the 
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target formation. UOG wells are also drilled vertically or directionally,5

 depending on the 

characteristics of the formation. Directional drilling is a technique used to drill a wellbore 

at an angle off of the vertical to reach an end location not directly below the well pad; 

horizontal drilling is considered a type of directional drilling. In UOG well drilling, well 

depths range from approximately 1,000 to 13,500 feet deep (but the majority of wells are 

drilled between 6,000 and 12,000 feet), wells often have a long horizontal lateral which 

can vary in length between 1,000 and 5,000 feet, and it takes approximately 5 to 60 days 

to complete well drilling. See TDD, Chapter B.3. 

2. Well Completion 

Once the target formation has been reached, and a determination has been made 

as to whether or not the formation has commercial potential, the well is made ready for 

production by a process termed “well completion.” Well completion involves cleaning 

the well to remove drilling fluids and debris, perforating the casing that lines the 

producing formation6

, inserting production tubing to transport the hydrocarbon fluids to 

the surface, installing the surface wellhead, stimulating the well, setting plugs in each 

stage, and eventually drilling the plugs out of the well and allowing fluids to return to the 

surface. During perforation, operators lower a perforation gun into the stage using a line 

wire. The perforation gun releases an explosive charge to create holes that penetrate 

approximately one foot into the formation rock in a radial fashion. These perforations 

create a starting point for the hydraulic fractures. 

 

5

 Shale oil and gas wells, are primarily drilled directionally (and specifically horizontally), while tight oil 

and gas wells are drilled vertically and directionally. 

6

 In some instances, open-hole completions may be used, where the well is drilled into the top of the target 

formation and casing is set from the top of the formation to the surface. Open-hole well completions leave 

the bottom of the wellbore uncased. 
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Since UOG resources are extracted from formations with low porosity and low 

permeability in which the natural reservoir and fluid characteristics do not permit the oil 

and/or natural gas to readily flow to the wellbore, hydraulic fracturing is often used to 

complete the well and extract UOG resources.7

 Although there are some vertical and 

directional UOG wells that are hydraulically fractured, existing literature indicates that 

the majority of UOG wells are horizontally drilled and hydraulically fractured. Therefore, 

the remainder of this discussion focuses on the hydraulic fracturing of horizontally drilled 

UOG wells; however, all drill types (including vertical and directional) would be covered 

by this proposed rule. 

Hydraulic fracturing involves the injection of fracturing fluids (e.g., mixtures of 

water, sand, and other additives) at high pressures into the well to create small fractures 

in the rock formation. The primary component of fracturing fluid is the base fluid into 

which proppant (e.g., sand) and chemicals are added. Currently, the most common base 

fluid is water; however, other fluids such as liquid nitrogen and propane (LPG) are also 

used. Historically, base fluid consisted exclusively of freshwater, but as more wastewater 

is increasingly reused/recycled, base fluid may contain mixtures of fresh water blended 

with reused/recycled UOG extraction wastewater. Chemical additives, used to adjust the 

fracturing fluid properties, vary according to the formation, target resource (e.g., shale 

oil), chemical composition of base fluid (e.g., volume of reused/recycled wastewater in 

base fluid), and operator preference (DCN SGE00721 DCN SGE00070; DCN 

SGE00780; DCN SGE00781). Additives commonly include, among other things, acids 

 

7

 Hydraulic fracturing techniques are also often used to improve recovery from conventional oil and gas 

wells. However, the scope of this section is focused on UOG extraction, therefore, the application of this 

process to conventional wells is not further discussed here. 
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(e.g., hydrochloric acid), biocides (e.g., glutaraldehyde), friction reducers (e.g., ethylene 

glycol, petroleum distillate), and gelling agents (e.g., guar gum, hydroxyethyl cellulose) 

(DCN SGE00721 DCN SGE00070; DCN SGE00780; DCN SGE00781). See TDD, 

Chapter C.1. 

The amount of fracturing fluid required per well typically depends on the well 

trajectory (e.g., vertical, horizontal), well length, and target resource (e.g., shale oil). 

UOG wells require between 50,000 to over ten million gallons of fracturing fluid per well 

(DCN SGE00532; DCN SGE00556; DCN SGE00637.A3). Operators typically fracture a 

horizontal well in eight to 23 stages using between 250,000 and 420,000 gallons (6,000 

and 10,000 barrels) of fracturing fluid per stage (SGE00280). Literature reports that tight 

oil and gas wells typically require less fracturing fluid than shale oil and gas wells (DCN 

SGE00533). 

Because laterals in horizontally drilled UOG wells are between 1,000 and 5,000 

feet long, operators typically hydraulically fracture horizontal wells in stages to maintain 

the high pressures necessary to stimulate the well over the entire length. Stages are 

completed starting with the stage at the end of the wellbore and working back towards the 

wellhead.8 Operators may use anywhere between eight and 23 stages (DCN SGE00280). 

A fracturing crew may fracture two to three stages per day when operating 12 hours per 

day or four to five stages per day when operating 24 hours per day.9

 Consequently, a 

 

8

 The first stage is fractured with what is known as the pad fracture. The pad is the injection of high 

pressure water and chemical additives (i.e., no proppant) to create the initial fractures into the formation. 

After the pad is pumped down hole, proppant is introduced to the fracturing fluid for the additional stages. 

9

 The hours per day depends on the operator, local ordinances, and weather. 
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typical well may take between two and seven days to complete (DCN SGE00239; DCN 

SGE00090). 

Once the stage is hydraulically fractured, a stage plug is inserted down the 

wellbore separating it from additional stages until all stages are completed. After all of 

the stages have been completed, the plugs are drilled out of the wellbore allowing the 

fracturing fluids and other fluids to return to the surface. At the wellhead, a combination 

of liquid (i.e., produced water), sand, oil, and/or gas are routed through phase separators 

that separate products from wastes. 

A portion of produced water may return to the wellhead at this time; this waste 

stream is often referred to as “flowback” and consists of the portion of fracturing fluid 

injected into the wellbore that returns to the surface during initial well depressurization 

often combined with formation water.10 Higher volumes of water are generated in the 

beginning of the flowback process. Over time, flowback rates decrease as the well goes 

into the production phase. Operators typically store flowback in 500 barrel fracturing 

tanks onsite before treatment or transport offsite.11 In addition to flowback, small 

quantities of oil and/or gas may be produced during the initial flowback process. The 

small quantities of produced gas may be flared or captured if the operator is using “green 

completions”, which involves capturing the gas rather than flaring.12 

 

10 Formation water is naturally occurring water contained in the reservoir rock pores.

11 Fracturing tanks cannot be transported when they contain wastewater. Wastewater is typically 

transported via trucks with approximately 100 to 120 barrel capacities or via pipe (DCN SGE00635). 

12 On April 17, 2012, the U.S. EPA issued regulations under the Clean Air Act, requiring the natural gas 

industry to reduce air pollution by using green completions, or reduced emission completions. EPA 

identified a transition period until January 1, 2015 to allow operators to locate and install green completion 

equipment (40 CFR part 60 and 63). 
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The flowback period typically lasts from a few days to a few weeks before the 

production phase commences (DCN SGE00010; DCN SGE00011; DCN SGE00622; 

DCN SGE00592; DCN SGE00286). At some wells, the majority of fracturing fluid may 

be recovered within a few hours (DCN SGE00010; DCN SGE00011; DCN SGE00622; 

DCN SGE00592; DCN SGE00286). See TDD, Chapter B.3. 

3. Production 

After the initial flowback period, the well begins producing oil and/or gas, this 

next phase is referred to as the production phase. During the production phase, UOG 

wells produce oil and/or gas and generate long-term produced water. Long-term 

produced water, generated during the well production phase, consists primarily of 

formation water and continues to be produced throughout the lifetime of the well, though 

typically at much lower rates than flowback (DCN SGE00592). This long-term produced 

water is typically stored onsite in tanks or pits (DCN SGE00280; DCN SGE00275; DCN 

SGE00636) and is periodically trucked, or sometimes piped, offsite for treatment, reuse, 

or disposal. See TDD, Chapter B.3. 

C. UOG Extraction Wastewater 

UOG extraction wastewater, as EPA proposes to define it (see Section VI.B.) 

includes the following sources of wastewater pollutants13: 

 Produced water – the water (brine) brought up from the hydrocarbon-bearing 

strata during the extraction of oil and gas. This can include formation water, 

 

13 Stormwater is not considered a source of UOG extraction wastewater. In general, no permit is required 

for discharges of stormwater from any field activities or operations associated with oil and gas production, 

except as specified in 40 CFR 122.26(c)(1)(iii) for discharges of a reportable quantity or that contribute to a 

violation of a water quality standard. 
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injection water, and any chemicals added downhole or during the oil/water 

separation process. Based on the stage of completion and production the well 

is in, produced water can be further broken down into the following 

components: 

o Flowback – After the hydraulic fracturing procedure is completed 

and pressure is released, the direction of fluid flow reverses, and 

the fluid flows up through the wellbore to the surface. The water 

that returns to the surface is commonly referred to as “flowback.” 

o Long-term produced water – This is the wastewater generated by 

UOG wells during the production phase of the well after the 

flowback process. Long-term produced water continues to be 

produced throughout the lifetime of the well. 

 Drilling wastewater, including: 

o Drill cuttings – The particles generated by drilling into subsurface 

geologic formations and carried out from the wellbore with the 

drilling fluid. 

o Drilling muds – The circulating fluid (mud) used in the rotary 

drilling of wells to clean and condition the hole and to 

counterbalance formation pressure. 

 Produced sand – The slurried particles used in hydraulic fracturing, the 

accumulated formation sands and scale particles generated during 

production. Produced sand also includes desander discharge from the 
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produced water waste stream, and blowdown of the water phase from the 

produced water treating system. 

The EPA identified drilling wastewater and produced water as the major sources of 

wastewater pollutants associated with UOG extraction, therefore, these wastewaters are 

described further below. 

1. Drilling Wastewater 

As discussed in Section XI.B.1., operators inject drilling fluids down the well 

bore during drilling to cool the drill bit and to remove fragments of rock (drill cuttings) 

from the wellbore (DCN SGE00090; DCN SGE00274). Drilling fluid can be water or 

synthetic based. Air has recently been used in place of drilling fluids in the vertical phase 

of wells. Operators may use a combination of drilling fluids and air during the drilling 

process of a single well. The drilling fluid used depends on the properties of the 

formation, the depth, and associated regulations, safety, and cost considerations (DCN 

SGE00090; DCN SGE00635; TDD Chapter B.3). 

When returned to the surface, ground rock removed from the wellbore (drill 

cuttings) is entrained in the drilling fluid. Operators separate the solids from the drilling 

fluid on the surface, striving to remove as much solids (i.e., drill cuttings) from the 

drilling fluid as possible. The separation process generates two streams: a solid waste 

stream referred to as drill cuttings and a liquid waste stream referred to as drilling 

wastewater. Operators typically transfer their drill cuttings to a landfill (DCN SGE00090, 

DCN SGE00635). Drilling wastewater is often reused/recycled until well drilling is 

complete (though in some cases it is processed for discharge and/or disposal). 
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At the end of drilling, operators use a variety of practices to manage drilling 

wastewater, primarily reuse/recycle in drilling subsequent wells. The following list 

presents drilling wastewater management options used by UOG operators (DCN 

SGE00740): 

 Reuse/recycle wastewater in subsequent drilling and/or fracturing jobs14

 Disposal via landfill15

 Disposal via underground injection wells 

 Land application 

 Transfer wastewater to a CWT facility 

 On-site burial15

Nearly all of the volume of drilling fluid circulated during drilling is recovered as 

drilling wastewater and requires management. Typical drilling wastewater volumes for 

UOG drilling vary from 100,000 to 300,000 gallons per well depending primarily on 

vertical depth, horizontal length, and the well bore diameter (DCN SGE00740). 

2. Produced Water 

a. Flowback 

As explained above, the portion of produced water that returns to the wellhead 

after the plugs are drilled out of the wellbore is often referred to as “flowback” and the 

largest daily volume of produced water generated occurs during the flowback period. 

Over time, flowback rates decrease as the well begins to produce oil and gas. Initially, 

flowback has characteristics that may resemble the fracturing fluid. During the flowback 

 

14 Synthetic fluids, which are more expensive than water-based drilling fluid, are almost always 

reused/recycled in drilling additional wells. 

15 Burial and landfill disposal options are generally limited to “semisolid” waste. Solidification processes 

may occur prior to transferring the waste to the landfill or they may occur at the landfill. (DCN 

SGE00139). 
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period, the generated wastewater increasingly resembles characteristics of the underlying 

formation. 

The volume of flowback produced by a well varies, and it is often looked at in 

relation to the volume of the fracturing fluid used to fracture the well (as explained in 

Section XI.B.2. above, fracturing fluid volumes used depend on many factors, including 

the total number of stages drilled). Flowback recovery percentages also vary due to 

factors such as resource type (e.g., shale oil) and well trajectory and have been 

documented anywhere between 3 and 75 percent of the volume of the fracturing fluid 

injected, with median flowback recovery between 4 and 29 percent (DCN SGE00724). 

These percent recoveries may result in total flowback volumes ranging from less than 

210,000 gallons per well to more than 2,100,000 gallons per well (5,000 to 50,000 barrels 

per well) (DCN SGE00724). See TDD, Chapter C. 2. 

b. Long-term Produced Water 

After flowback generation, long-term produced water is generated during the well 

production phase. Long-term produced water has characteristics that primarily reflect the 

formation. The long-term produced water flow rate from a UOG well gradually decreases 

over time. In addition, the amount of produced water generated per well varies by 

formation. Median long-term produced water flow rates vary by resource type (e.g., shale 

oil) and well trajectory and can be between 200 and 800 gallons per day (4.8 to 19 barrels 

per day), depending on well trajectory, formation type and well age (DCN SGE00635; 

DCN SGE00724). See TDD, Chapter C.2. 
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D. UOG Extraction Wastewater Characteristics 

The EPA reviewed published characterization data for UOG extraction 

wastewater. Produced water data included measurements of total dissolved solids (TDS), 

anions/cations, metals, hardness, radioactive constituents, and organics. Drilling 

wastewater characterization data included suspended solids, salts, metals, and organics. 

Because drilling wastewater is typically recycled/re-used for drilling another well, 

detailed pollutant specific information is less readily available for drilling wastewater 

than for produced water. As such, the remainder of this section is specific to produced 

water.16

1. TDS and TDS-Contributing Ions 

The characteristics of UOG produced water vary primarily depending on the 

characteristics of the UOG formation (DCN SGE00090). The primary constituents found 

in UOG produced water are total dissolved solids (TDS), anions/cations, metals, 

hardness, and radioactive constituents. 

TDS provides a measure of the dissolved matter, including salts (e.g., sodium, 

chloride, nitrate), organic matter, and minerals (DCN SGE00046). TDS is not a specific 

chemical, but is defined as the portion of solids that pass through a filter with a nominal 

pore size of 2.0 micron (μm) or less (EPA Method 160.1). Table XI-1. shows ranges and 

median TDS concentrations associated with various shale and tight oil and gas 

formations. 

 

16 As explained above, produced water includes both flowback and long-term produced water. 
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Table XI-1. Concentrations of TDS in Produced Waters in Various UOG 

Formations 

Shale/Tight Oil and Gas 

Formation 

TDS Concentration 

Range (mg/L) 

TDS Median 

Concentration (mg/L) 

Number of 

Data Points 

Bakken 98,000 – 220,000 150,000 13

Barnett 25,000 – 150,000 50,000 40

Bradford-Venango-Elk (Tight) 32,000 – 400,000 180,000 5

Cleveland (Tight) 84,000 – 220,000 120,000 11

Cotton Valley/Bossier (Tight) 110,000 – 230,000 170,000 3

Dakota (Tight) 2,900 – 7,700 6,000 3

Devonian 320 – 250,000 130,000 11

Eagle Ford 3,700 – 89,000 21,000 1,648

Fayetteville 13,000 – 57,000 25,000 6

Haynesville/Bossier 110,000 – 120,000 120,000 2

Marcellus 680 – 350,000 92,000 383

Mississippi Lime (Tight) -- 150,000 1

New Albany -- 88,000 1

Niobrara 39,000 – 140,000 100,000 8

Pearsall 300,000 – 380,000 370,000 3

Spraberry (Tight) 58,000 – 160,000 130,000 26

Utica 6,500 – 44,000 16,000 8

Woodford-Cana-Caney 14,000 – 110,000 36,000 8

Source: See TDD, Chapter C.3. 

Salts are the majority of TDS in UOG produced water, and sodium chloride 

constitutes approximately 50 percent of the TDS in UOG produced water (DCN 

SGE00046). In addition to sodium and chloride, UOG produced water typically contains 

divalent cations such as calcium, strontium, magnesium, and, in some formations, barium 

and radium. Other ions such as potassium, bromide, fluoride, nitrate, nitrite, phosphate, 

and sulfate may also contribute to TDS in UOG produced water. Metals, other than those 

contributing to TDS (e.g., calcium, magnesium, strontium), are typically not found in 

high concentrations in UOG produced water. Table XI-2. presents ranges and median 

concentrations of TDS and TDS-contributing ions in UOG produced water. Based on 

available data, concentrations of TDS and TDS-contributing ions, including divalent 

cations, typically increase from flowback to long-term produced water. See TDD, 

Chapter C.3. 
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Table XI-2. Concentrations of TDS and TDS-Contributing Ions in UOG 

Produced Waters 

Constituent 

Concentration Range 

(mg/L) 

Median Concentration 

(mg/L) 

Number of Data 

Points 

TDS 20 – 400,000 110,000 2,223

Chloride 64 – 230,000 48,000 2,063

Sodium 64 – 98,000 25,000 1,913

Calcium 13 – 34,000 3,400 2,068

Strontium 0 – 8,000 580 207

Magnesium 3 – 15,000 570 2,030

Bromide 0.2 - 4,300 540 119

Potassium 0 - 5,800 290 344

Barium 0 - 16,000 100 289

Sulfate 0 - 3,400 71 1,585 

Phosphate 12 - 88 12 3 

Nitrate 5 - 10 5 3 

Nitrite -- 5 2 

Fluoride 0.045 - 390 2.5 99 

Source: See TDD, Chapter C.3. 

2. Organic Constituents 

Organic constituents in UOG produced water may originate from both the 

fracturing fluid that is injected down the wellbore and from the UOG formation itself. 

Organic constituents and hydrocarbons in UOG produced water appear to be less 

frequently sampled in comparison to the well-documented TDS concentrations. The EPA 

has reviewed available data on organic pollutants in produced water and found a range of 

pollutant concentrations: phenol (0.7 to 460 ppb), pyridine (1.1 to 2,600 ppb), benzene 

(0.99 to 800,000 ppb), ethyl benzene (0.63 to 650 ppb), toluene (0.91 to 1,700,000 ppb), 

and total xylenes (3 to 440,000) (DCN SGE00724). See TDD, Chapter C.3. 

3. Radioactive Constituents 

Oil and gas formations contain varying levels of radioactivity resulting from 

uranium decay which can be transferred to UOG produced water. Radioactive decay 

products typically include uranium 238, radium 226, and radium 228. The EPA identified 
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available data on some radioactive elements in UOG produced water, including radium 

226, radium 228, gross alpha, and gross beta, and, therefore, focused the radioactive 

constituent discussion and data presentation on data for these parameters. Radium 226, 

which has a half-life over 1,000 years, has been found in UOG produced water at 

concentrations up to 16,900 picocuries per liter (pCi/L) (DCN SGE00241; DCN 

SGE00724). As a point of comparison, the International Atomic Energy Agency (IAEA) 

published a report in 2014 that included radium isotope concentrations in rivers and 

lakes. The average of measured concentrations of radium 226 found in U.S. rivers and 

lakes was 0.56 pCi/L (21 millibecquerel per liter (mBq/L)) and the measured values 

ranged from 0.01 to 1.7 pCi/L (0.37 to 63 mBq/L) (DCN SGE00769). Data for radium 

228 were limited. 

Data characterizing produced water radioactivity concentrations were not 

available for all shale and tight oil and gas formations. However, the available data from 

five different tight or shale oil and gas formations show that the concentrations of one or 

more radioactive constituents (i.e., radium 226, radium 228, gross alpha, gross beta) in 

UOG produced water was above naturally occurring concentrations in rivers and lakes 

throughout the world. The highest reported radium 228 value was in the Ganges River in 

India and was measured at 0.07 pCi/L (2.6 mBq/L). (See DCN SGE00769) 

E. Wastewater Management and Disposal Practices 

Historically, UOG operators primarily managed their wastewater using the 

following four methods17: 

 

17 Occasionally, UOG operators in the western U.S. may use evaporation as a means of wastewater 

management. 
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 Disposal via underground injection wells; 

 Reuse in subsequent fracturing jobs; 

 Transfer to a POTW; or 

 Transfer to a privately owned wastewater treatment facility (also called 

centralized waste treatment (CWT) facilities).18

(DCN SGE00613; DCN SGE00276); DCN SGE00528). 

The frequency with which UOG operators use each of the management options 

listed above varies by operator, formation, and sometimes within each region of the 

formation (DCN SGE00579; DCN SGE00276). This proposed rule addresses only 

transfers to a POTW. Historically, the oil and gas industry has most commonly managed 

its wastewater by underground injection (DCN SGE00182), but the industry is 

increasingly turning to reuse, and in some areas transfer to CWT facilities, to manage 

increasing volumes of UOG extraction wastewater (see TDD, Chapter D). 

1. Injection into Disposal Wells 

Underground injection involves pumping wastes into a deep underground 

formation with a confining layer of impermeable rock. The receiving formation must also 

be porous enough to accept the wastewater. Historically, underground injection has been 

the most commonly used UOG extraction wastewater management method. As of 2009, 

over 90 percent of oil and gas wastewater (conventional and unconventional) was 

disposed of via Class II injection wells (DCN SGE00623; DCN SGE00132). 

 

18 Operators may haul wastewater to CWT facilities that handle the wastewater by (1) treating for reuse; (2) 

direct discharging to surface water; or (3) indirect discharging to surface water through a POTW. 
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The availability of underground injection as a disposal method varies by state. 

Some states have a large number of Class II disposal wells (e.g., Texas, Oklahoma, 

Kansas) while others have very few (e.g., Pennsylvania, West Virginia). In many UOG 

formations, distances from the average producing well to the nearest disposal well are 

short and disposal capacity is abundant making it the least expensive disposal practice 

(DCN SGE00635). 

2. Reuse in Fracturing 

Reuse involves mixing flowback and/or long-term produced water from 

previously fractured wells with source water19 to create the base fluid used to fracture a 

new well (DCN SGE00046). Reused UOG extraction wastewater is typically transported, 

by truck, from storage to the fracturing site just prior to the start of hydraulic fracturing. 

When hydraulic fracturing commences, the stored UOG wastewater is pumped from the 

fracturing tanks and blended with source water to form the base fluid. The blending 

occurs upstream of other steps such as sand and fracturing chemical addition or 

pressurization by the pump trucks (DCN SGE00625). 

In considering whether to reuse wastewater, operators evaluate wastewater 

generation rates compared to water demand for new fracturing jobs, water quality and 

treatment requirements for use in fracturing, and the risks and costs of wastewater 

management and transportation for reuse compared to disposal, or transfer practices. 

Typically, for an operator to reuse wastewater, the cost per barrel for reuse must be less 

than the cost per barrel for disposal or transfer (DCN SGE00095). The cost for reuse 

 

19 Source waters may include freshwater, ground water, treated municipal wastewater, and other industrial 

wastewater. 
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depends on several factors that vary by formation and operator; and, therefore, the 

potential for reusing UOG extraction wastewater for fracturing varies by formation and 

operator. 

Since the late 2000’s, UOG operators have increased wastewater reuse (DCN 

SGE00613). The Petroleum Equipment Suppliers Association (PESA) surveyed 205 

UOG operators in 2012 about their wastewater management practices. Survey results 

included 143 operators active in major UOG formations. UOG operators reported reusing 

23 percent of the total volume of wastewater generated to refracture another well. The 

survey results also showed that most operators anticipated reusing higher percentages of 

their wastewater in the two to three years following the survey (DCN SGE00707; DCN 

SGE00708; DCN SGE00575). The EPA participated in several site visits and conference 

calls with operators in several UOG formations that have been able to reuse 100 percent 

of the volume of their wastewater under certain circumstances (DCN SGE00625; DCN 

SGE00635; DCN SGE00275; DCN SGE00636).

3. Transfer to Centralized Waste Treatment Facilities 

Some operators manage UOG extraction wastewater by transporting it to 

centralized waste treatment (“CWT”) facilities for treatment. Following treatment, these 

facilities may return it to an operator for reuse to fracture another well (“zero discharge”) 

and/or discharge it, either to surface water or to a POTW. Operators may choose to use 

CWT facilities if they drill and complete relatively few wells, making discharging to 

CWT facilities more feasible than investing in other management options (DCN 

SGE00300), or if other wastewater management options are not available or cost 

effective in the region where they are operating (DCN SGE00139; DCN SGE00182). The 
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EPA identified 73 commercial CWT facilities that accept UOG extraction wastewater. 

See TDD, Chapter D.3. The EPA found that the number of CWT facilities available to 

operators in the Marcellus and Utica Shale formations has increased with the number of 

wells drilled. A similar trend was observed in the Fayetteville Shale formation in 

Arkansas (DCN SGE00704). 

Operators may haul their wastewater to “zero discharge” CWT facilities that treat 

but do not discharge UOG extraction wastewater, either to surface water or to a POTW. 

Instead, they return the wastewater to UOG operators for reuse in subsequent hydraulic 

fracturing jobs. Commercial CWT facilities that fall into this category typically allow 

operators to unload a truck load of wastewater for treatment and take a load of treated 

wastewater on a cost per barrel basis (DCN SGE00245). Some of these facilities offer 

operators the option of unloading a truck load of wastewater without taking a load of 

treated wastewater for a surcharge, as long as other operators are in need of additional 

treated wastewater. The CWT facility may also provide this service if it can dispose of 

the wastewater without discharge (DCN SGE00299). For example, one facility in 

Wyoming treats UOG extraction wastewater for reuse by removing TDS and other 

pollutants through electrocoagulation followed by reverse osmosis (RO). The facility 

evaporates the concentrated brine from the RO unit in large evaporation ponds to dispose 

of wastewater not reused by operators (DCN SGE00374). 

Some operators may haul their wastewater to CWT facilities that discharge 

directly to surface waters. Discharges from these CWT facilities are controlled by 

NDPES permits that include pollutant discharge limitations based on the technologybased ELGs set out in 40 CFR part 437 (representing the floor), or more stringent effluent 
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limitations if the technology-based effluent limits are not sufficiently stringent to meet 

applicable state water quality standards. The ELGs do not include limitations for TDS; 

however, to meet applicable state water quality standards, direct discharging CWT 

facilities may use treatment processes (e.g., evaporation/condensation, reverse osmosis) 

that remove TDS. 

Finally, other operators may haul their wastewater to CWT facilities that 

discharge indirectly to a POTW. Discharges from the CWT facility to the POTW are 

controlled by an Industrial User Agreement (IUA) that must incorporate the pretreatment 

standards set out in 40 CFR part 437. 

4. Transfer to POTWs 

Historically, in locations where disposal wells and CWT facilities were limited, 

operators had managed UOG extraction wastewater by transfer to POTWs (DCN 

SGE00739; DCN SGE00598). This practice can be problematic because POTWs are not 

able to remove many of the constituents found in UOG extraction wastewater (DCN 

SGE00011; DCN SGE00600; DCN SGE00765). Because they are not typical of POTW 

influent wastewater, UOG extraction wastewater constituents may be discharged, largely 

untreated, from the POTW to the receiving stream, may disrupt the operation of the 

POTW (e.g., by inhibiting biological treatment), may accumulate in biosolids, limiting its 

use; and may facilitate the formation of harmful disinfection by-products (DBPs) (which 

are a concern for downstream drinking water uses). These constituents may interfere with 

POTW operations and may increase salt loads in receiving streams to the detriment of 

downstream water use. (DCN SGE00286; DCN SGE00345; DCN SGE00579; DCN 

SGE00531; DCN SGE00633). See TDD, Chapter D.5. As discussed above, the EPA has 
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not been able to identify any existing UOG discharges at present to POTWs. (DCN 

SGE00579; DCN SGE00286; DCN SGE00345). 

XII. Subcategorization 

In developing ELGs, the EPA may divide an industry category into groupings 

called "subcategories" to provide a method for addressing variations among products, 

processes, and other factors, which result in distinctly different effluent characteristics 

that affect the determination of the “best available” technology. See Texas Oil & Gas 

Ass'n. v. US EPA, 161 F.3d 923, 939-40 (5th Cir.1998). Regulation of a category by 

subcategories provides that each subcategory has a uniform set of effluent limitations or 

pretreatment standards that take into account technological achievability, economic 

impacts, and non-water quality environmental impacts unique to that subcategory. In 

some cases, effluent limitations or pretreatment standards within a subcategory may be 

different based on consideration of these same factors, which are identified in CWA 

section 304(b)(2)(B). The CWA requires the EPA, in developing effluent guidelines and 

pretreatment standards, to consider a number of different factors, which are also relevant 

for subcategorization. The CWA also authorizes the EPA to take into account other 

factors that the Administrator deems appropriate. CWA section 304(b). 

Within the oil and gas extraction category, the EPA has already established 

subcategories. As explained in Section VII.C., the existing oil and gas extraction ELGs 

are divided into five subcategories. The scope of the proposed rule is specific to subpart 

C: onshore. The proposed rule is specific to pollutant discharges from UOG extraction as 

defined in Section X. The EPA considered whether further subcategorization of the UOG 

extraction industry was warranted. The EPA evaluated a number of factors including 
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available data regarding wastewater chemical constituents, generation volumes, and rates. 

Although some differences can be observed among these characteristics (between 

different types of unconventional resource and geologic formations, and sometimes 

between wells within the same source), the EPA proposes that further subcategorization 

is not appropriate because the EPA has not identified any onshore UOG operations that 

currently discharge to POTWs. 

XIII. Proposed Regulation 

A. Discussion of Options 

1. PSES and PSNS Option Selection 

The EPA proposes to establish PSES and PSNS that apply to wastewater 

discharges from onshore UOG extraction facilities. Generally, the EPA designs PSES and 

PSNS to ensure that wastewaters from direct and indirect industrial dischargers are 

subject to similar levels of treatment prior to discharge to waters of the U.S. This means 

that, typically, the requirements for indirect dischargers are analogous to those for direct 

dischargers. As explained in Section VII.C., the existing requirements for BPT for the 

Onshore Subcategory are zero discharge of wastewater pollutants into waters of the U.S. 

from any source associated with production, field exploration, drilling, well completion, 

or well treatment. 

Most POTWs are designed primarily to treat municipally generated wastewater. 

POTWs typically provide at least secondary level treatment and, thus, are designed to 

remove settleable solids, suspended solids and organic material using biological 

treatment. The EPA is not aware of any POTWs that are designed to treat dissolved 

pollutants in UOG extraction wastewater such as TDS (e.g., chlorides, sulfates, metals) or 
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radioactive elements. As a result, the mass of untreated pollutants would be discharged 

from the POTW to the receiving water; or the pollutants could disrupt the operation of 

the POTW (e.g., by inhibiting biological treatment) or could facilitate the formation of 

harmful disinfection by-products (DBPs). 

As explained in Section XI.E., the EPA evaluated the practices currently used to 

manage UOG extraction wastewaters. Based on the information reviewed as part of this 

proposed rulemaking, the EPA identified that current industry practice is not to discharge 

pollutants from onshore UOG extraction to POTWs. Rather, the vast majority of this 

wastewater is managed by disposal in underground injection wells and/or re-use in 

fracturing another well.20 A small, but in some geographic areas increasing, portion of the 

industry also transfers its wastewater to privately owned wastewater treatment facilities 

(also referred to as centralized waste treatment, or CWT, facilities). 

Because of this information, the EPA identified one candidate PSES/PSNS 

option; that is, zero discharge of wastewater pollutants to POTWs. UOG extraction 

wastewater is discussed in Section XI.C. 

The technology basis for the proposed PSES is disposal in UIC wells and/or 

wastewater reuse/recycling to fracture another well. Because existing UOG extraction 

facilities currently employ alternative wastewater management practices, the technology 

basis for meeting a zero discharge requirement is widely available. While the EPA 

 

20 While pollutant discharges from onshore oil and gas extraction produced water are allowed under 

subpart E in certain geographic locations for use in agriculture or wildlife propagation, the EPA has not 

identified any permits for unconventional oil and gas (as defined for the proposed rule) that allow such 

discharges. 
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estimates that there will be no incremental pollutant reductions associated with the 

proposed PSES, the technology basis is best performing in that it achieves zero 

discharges of pollutants in UOG extraction wastewater. Additionally, because this 

technology represents current industry practice nationwide, no facilities will incur 

incremental costs for compliance with the proposed PSES and, therefore, the proposed 

PSES is economically achievable. For the same reasons, the proposed PSES will result in 

no incremental non-water quality environmental impacts. Finally, because the proposal 

represents current industry practice, the EPA proposes that PSES requiring zero discharge 

of wastewater pollutants be effective as of the effective date of this rule. 

As previously noted, under section 307(c) of the CWA, new sources of pollutants 

into POTWs must comply with standards which reflect the greatest degree of effluent 

reduction achievable through application of the best available demonstrated control 

technologies. Congress envisioned that new treatment systems could meet tighter 

controls than existing sources because of the opportunity to incorporate the most efficient 

processes and treatment systems into the facility design. The EPA proposes PSNS that 

would control the same pollutants using the same technologies proposed for control by 

PSES. The technologies used to control pollutants at existing sources, disposal in UIC 

wells and/or wastewater reuse/recycling to fracture another well, are fully available to 

new sources. They achieve the greatest degree of effluent reduction available: zero 

discharge of pollutants in UOG extraction wastewater. Furthermore, the EPA has not 

identified any technologies that are demonstrated to be available for new sources that are 

different from those identified for existing sources. Finally, the EPA determined that the 

proposed PSNS present no barrier to entry. While the EPA cannot say with certainty 
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exactly how new sources will manage their UOG extraction wastewater, information in 

the record indicates that new sources would continue to manage their UOG extraction 

wastewater following current industry practice. The EPA has found that overall impacts 

from the proposed standards on new sources would be minimal, as for existing sources, 

since the costs faced by new sources generally will be the same as those faced by existing 

sources. The EPA projects no (and, therefore, acceptable) incremental non-water quality 

environmental impacts. Therefore, the EPA proposes to establish PSNS that are the same 

as those proposed for PSES. 

2. Other Options Considered 

a. “No Rule” 

In addition to the PSES/PSNS option of zero discharge of wastewater pollutants, 

the EPA also considered the option of no proposed PSES or PSNS, a “no rule” option. 

Based on the discussion above that no UOG facilities are currently transferring 

wastewater to POTWs, and given available alternative management options such as 

disposal in UIC wells and reuse/recycling, the EPA considered the option of no proposed 

rule. A “no rule” option would impose no change to the existing pretreatment regulatory 

regime, or industry practice, and would, therefore, be a “no incremental cost and 

pollutant reduction” option. 

The EPA, however, did not select this “no rule” option for several reasons. First, 

there is no national federal regulation that would prevent or require pretreatment of such 

discharges – and, as mentioned above, the EPA is not aware of any POTWs that are 

designed to treat dissolved pollutants common in UOG extraction wastewater. This 

means that constituents of such wastewater could be discharged to receiving waters when 
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other [available] options such as reuse and proper disposal in a Class II UIC well better 

protect water quality and aquatic communities and help further the zero discharge goal of 

the CWA. CWA section 101(a)(1). Second, few states have regulations or policies that 

prevent discharges of pollutants in UOG extraction wastewater to POTWs or that 

mandate pre-treatment prior to discharge to a POTW. In the absence of such regulations 

or policies, resource-constrained control authorities and/or POTWs must evaluate 

transfers of UOG extraction wastewater to POTWs on a case-by-case basis. Third, history 

demonstrates that absent controls preventing the transfer of or requiring pretreatment of 

such wastewater, POTWs may accept it, as occurred in Pennsylvania (see TDD Chapters 

A.2 and D.5), where POTWs were used to manage UOG extraction wastewater until the 

state took action, including promulgating new regulations requiring pretreatment. 

Among the drivers behind these actions taken by Pennsylvania was that some waters 

were impaired by TDS. (DCN SGE00187). 

To avoid future scenarios where POTWs receive UOG extraction wastewater, it is 

reasonable to solidify the good practice already adopted by the industry that is 

technologically and economically viable. Moreover, it is beneficial to the states as a 

practical matter to establish federal regulations that mandate this existing practice, in 

order to avoid the burden for each state to potentially repeat the effort of promulgating 

state-level regulations. The EPA has discussed this proposed rule with several states, who 

have indicated a federal pretreatment standard would reduce their administrative burden 

(DCN SGE00762; DCN SGE00762; DCN SGE00743). 

The EPA also considered the future burden that continued lack of pretreatment 

standards may impose on POTWs. The UOG extraction industry is predicted to continue 
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to grow in the future, resulting in the installation, fracturing, and possible refracturing of 

hundreds of thousands of wells. Well operators will continue to generate UOG extraction 

wastewater and may request local POTWs to accept their wastewater for discharge. In the 

absence of federal pretreatment standards, POTWs may legally accept UOG extraction 

wastewater to the extent that such wastewater transfers are in compliance with state and 

local requirements. Evaluating each potential customer (industrial user), developing a 

determination for each new UOG extraction wastewater source on a case-by-case basis, 

and, where a POTW determines it may accept this wastewater, complying with applicable 

reporting requirements may be a significant burden to some POTWs. The EPA 

concluded that a national-level determination that UOG extraction wastewater contains 

pollutant concentrations that will pass through POTWs, and development of categorical 

pretreatment standards, will avoid burdening individual POTWs with evaluating each 

individual request. Thus, the national categorical pretreatment standards will reduce the 

process burden on pretreatment Control Authorities (e.g., POTWs). While the EPA does 

not have the information to quantify the reductions in administrative burden that will 

likely result from the proposed rule, states generally support the EPA’s position that such 

reductions will be realized (DCN SGE00762; DCN SGE00762; DCN SGE00743). 

Moreover, as explained above, because some pollutants of concern in UOG 

extraction wastewater will not be physically, chemically, or biologically reduced by the 

treatment processes typically used at POTWs, these pollutants are expected to be 

discharged from the POTW into receiving waters. In addition, these pollutants can cause 

operational problems for the POTW’s biological treatment processes and alter the 

POTW’s ability to adequately remove BOD, TSS, and other pollutants for which it is 
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regulated. For some UOG pollutants, such as radionuclides, the data indicate POTWs 

will remove some portion while discharging the remainder (DCN SGE00136). In these 

cases, some portion of the radionuclides will partition to the POTW biosolids, which may 

cause the POTW to incur increased costs to change its selected method of biosolids 

management (DCN SGE00615). See also TDD Chapter D.5. 

Finally, the EPA did not select the “no rule” option because it concluded that 

national pretreatment standards provide clear direction and certainty to industry, POTWs, 

states, and the public that UOG extraction wastewaters are not treated by POTWs and 

should not be transferred to them. Categorical pretreatment standards support the CWA 

goal that the discharge of pollutants into the nation’s navigable waters be eliminated. 

CWA section 101(a). 

b. Non-Zero Numeric Discharge Pretreatment Requirements 

The EPA considered an option that would have included non-zero numerical 

discharge pre-treatment requirements prior to discharge to a POTW. Such an option 

could be similar to the one adopted in Pennsylvania in 2010 that requires pretreatment of 

oil and gas wastewaters before discharge to a POTW to meet a maximum TDS 

concentration of 500 mg/L as well as specific numerical concentrations for other 

pollutants. Some have suggested this would provide an “escape-valve” for the future in 

the event that UIC disposal well capacity is exhausted. Others have suggested this would 

allow the water to be available for re-use (other than in fracturing another well) if 

technologies become available to pre-treat it to remove dissolved pollutants in a cost 

effective manner. 
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The EPA does not propose an option with numerical discharge pretreatment 

requirements prior to discharge to a POTW for the following reasons. First, the existing 

requirements for direct discharges of UOG extraction wastewater in the Onshore 

Subcategory require no discharge of pollutants. As explained above, the EPA generally 

establishes requirements for direct and indirect discharges so that the wastewater receives 

comparable treatment prior to discharge to waters of the U.S. 

Second, the option EPA proposes, zero discharge of pollutants in UOG extraction 

wastewater to POTWs, is widely available, economically achievable and has no 

incremental (and, therefore, acceptable) non-water quality environmental impacts. 

Because the proposed zero pollutant discharge requirement is current practice and, 

therefore, clearly both available and achievable, any option that includes non-zero 

discharge requirements for any pollutants would potentially increase pollutant discharges 

from current industry best practices. Such an option would not fulfill the CWA 

requirement to establish limitations based on “Best Available Technology Economically 

Achievable” (CWA section 301(b)(2)(A)), or the CWA goals of eliminating the discharge 

of pollutants into navigable waters (CWA section 101(a)(1)). 

Third, the EPA does not have any data to demonstrate that UIC capacity 

nationwide will be expended and that this current management approach will not be 

available in the future (DCN SGE00613). In fact, industry has been managing oil and 

gas extraction wastewater through underground injection for decades. In recent years, 

industry has greatly expanded its knowledge about the ability to re-use UOG flowback 

and long-term produced water (the major contributors to UOG extraction wastewater by 

volume) in fracturing another well. Consequently, while the UOG industry continues to 
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grow and new wells are being fractured, the need for UIC capacity for UOG extraction 

wastewater is decreasing, even in geographic locations with an abundance of UIC 

capacity (see TDD Chapter D.2). 

Fourth, the EPA identified technologies that currently exist to treat dissolved 

pollutants in UOG extraction wastewater. Relative to underground injection and 

reuse/recycling to fracture another well (the basis for the preferred option EPA proposes), 

these technologies are costly, would result in more pollutant discharges, and are energy 

intensive. While the EPA did not attempt to calculate a numerical standard for TDS, data 

collected for this proposed rulemaking demonstrate that the current technologies are 

capable of reducing TDS (and other dissolved pollutants) well below 500 mg/L. To the 

extent that these technologies or others are developed in the future to reduce pollutants in 

UOG extraction wastewater to enable them to be reused for purposes other than 

fracturing another well, these pre-treated wastewaters may be used directly for the other 

applications without going through a POTW.21 

c. Conventional Oil and Gas Wastewater 

 As explained in Section VII., while the existing oil and gas regulation applies to 

both conventional and UOG extraction (except coalbed methane), the proposed rule 

would add pretreatment standards only for facilities engaged in oil and gas extraction 

from UOG sources that send their discharges to POTWs. EPA proposes to reserve 

standards for conventional oil and gas extraction for possible future rulemaking, if 

 

21 As a point of clarification, except in certain geographic areas, these wastewaters would remain subject to 

the requirements in the Onshore Subcategory that require no discharge of pollutants to waters of the U.S. 

(40 CFR 435.30). 
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appropriate. This is consistent with the EPA’s stated scope throughout the development 

of this proposed rule. The EPA has proposed a definition of unconventional operations, 

but solicits comment on whether the proposed definition of unconventional operations is 

sufficiently clear to enable oil and gas extraction operators and/or pretreatment 

authorities to determine whether specific wastewaters are from conventional or 

unconventional sources. See Section X. To help inform any possible future rulemaking 

for pretreatment standards for conventional oil and gas operations, the EPA requests data 

on the volumes of and pollutants in wastewater generated from conventional oil and gas 

extraction. The EPA also requests data on the prevalence of conventional oil and gas 

wastewater discharges to POTWs, including information on any pretreatment that may be 

applied, geologic formations the gas or oil is extracted from, and locations within the 

United States. (See Section XI.). 

B. Pollutants of Concern 

Since the effectiveness of the technology basis for the proposed standards results 

in zero discharge of all pollutants, it is not appropriate in this proposed rule to specify the 

pollutants of concern. Rather, as is the case for the existing BPT requirements, the 

proposed PSES/PSNS apply to the discharge of all pollutants in UOG extraction 

wastewater. 

C. POTW Pass Through Analysis 

Sections 307(b) and (c) of the CWA authorize the EPA to promulgate 

pretreatment standards for pollutants that are not susceptible to treatment by POTWs or 

which would interfere with the operation of POTWs. The EPA looks at a number of 

factors in selecting the technology basis for pretreatment standards for existing and new 
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sources. These factors are generally the same as those considered in establishing the 

direct discharge technology basis. However, unlike direct dischargers whose wastewater 

will receive no further treatment once it leaves the facility, indirect dischargers send their 

wastewater to POTWs for further treatment. 

Therefore, before establishing PSES/PSNS for a pollutant, the EPA examines 

whether the pollutant “passes through” a POTW to waters of the U.S. or interferes with 

the POTW operation or biosolids disposal practices. In determining whether a pollutant 

would pass through POTWs for these purposes, the EPA generally compares the 

percentage of a pollutant removed by well-operated POTWs performing secondary 

treatment to the percentage removed by a candidate technology basis. A pollutant is 

determined to pass through POTWs when the median percentage removed nationwide by 

well-operated POTWs is less than the median percentage removed by the candidate 

technology basis. Pretreatment standards are established for those pollutants regulated 

under the direct discharge level of control (typically BAT/NSPS) that passes through. In 

addition, the EPA may regulate pollutants that do not pass through but otherwise interfere 

with POTW operations or biosolids disposal practices. This approach to the definition of 

pass through satisfies two competing objectives set by Congress: (1) that standards for 

indirect dischargers be equivalent to standards for direct dischargers, and (2) that the 

treatment capability and performance of POTWs be recognized and taken into account in 

regulating the discharge of pollutants from indirect dischargers. 

In the case of the proposed rule, the candidate technology basis would prevent the 

discharge of all pollutants to POTWs completely. Historically, the EPA’s primary source 

of POTW removal data is its 1982 “Fate of Priority Pollutants in Publicly Owned 
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Treatment Works” (also known as the 50 POTW Study) (see DCN SGE00765). The 50 

POTW study presents data on the performance of 50 POTWs achieving secondary 

treatment in removing toxic pollutants. While the 50 POTW study demonstrates a wide 

variability in the effectiveness of POTWs in removing toxic pollutants, it demonstrates 

that POTWs remove these toxic pollutants by less than 100%. Although this study does 

not contain information on pollutant removals for TDS, as explained earlier, secondary 

treatment technologies are generally understood to be ineffective at removing TDS and as 

such little to no TDS removals are likely to occur at POTWs (DCN SGE00011; DCN 

SGE00600). Therefore, based on the 50 POTW study of toxic pollutants and information 

about secondary treatment removal of TDS, the EPA determined that all pollutants would 

“pass through” the POTW for the UOG extraction wastewater as that term applies in the 

CWA. 

XIV. Environmental Impacts 

UOG production generates significant volumes of wastewater that need to be 

managed. As described in Section XI.C.2, wells may produce flowback volumes ranging 

between 210,000 and 2,100,000 gallons. During the production phase, wells typically 

produce smaller volumes of water (median flow rates range from 200-800 gallons per 

day) and continue producing wastewater throughout the life of the well. 

 In general, evidence of environmental impacts to surface waters from discharges 

of UOG extraction wastewater is sparsely documented. Some of the environmental 

impacts documented to date resulted from wastewater pollutants that passed untreated 

through POTWs in Pennsylvania (TDD, Chapter D.5). 
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A. Pollutants 

As described in Section XI.D., high concentrations of TDS are common in UOG 

extraction wastewater. As shown in Table XI-2. (in Section XI.D.), major inorganic 

constituents leaching from geologic formations such as sodium, potassium, bromide, 

calcium, fluoride, nitrate, phosphate, chloride, sulfate, and magnesium represent most of 

the TDS in UOG extraction wastewater. TDS in produced water may also include 

barium, radium, and strontium. Based on available data, TDS cations (positively charged 

ions) in UOG extraction wastewater are generally dominated by sodium and calcium, and 

the anions (negatively charged ions) are dominated by chloride (DCN SGE00284). TDS 

concentrations vary among the UOG formations. Table VII-1 (in Section XI.D.), presents 

the varying TDS concentrations in tight and shale oil and gas formations. The highest 

median TDS concentration (370,000 mg/L) is found in the Pearsall shale gas formation. 

For comparison, sea water contains approximately 35,000 mg/L TDS. 

B. Impacts from the Discharge of Pollutants Found in UOG Extraction Wastewater 

Conventional POTW treatment operations are designed primarily to treat organic 

waste and remove biochemical oxygen demand and total suspended solids, not to treat 

waters with high TDS. When discharges to POTWs were occurring in Pennsylvania, 

these POTWs, lacking adequate TDS removal processes, diluted UOG extraction 

wastewaters with other sewage flows and discharged TDS-laden effluent into local 

streams and rivers. POTWs not sufficiently treating TDS in UOG extraction wastewater 

were a suspected source of elevated TDS levels in the Monongahela River in 2009 (DCN 

SGE00525). Also see TDD, Chapter D.5 for additional examples. 
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In addition to UOG wastewater pollutants passing through POTWs, other 

industrial discharges of inadequately treated UOG extraction wastewater pollutants have 

also been associated with in-stream impacts. One study reviewed by the EPA of 

discharges from a CWT facility in western Pennsylvania that treats UOG extraction 

wastewater examined the water quality and isotopic compositions of discharged effluents, 

surface waters, and stream sediments (DCN SGE00629).22 The study found that the 

discharge of the effluent from the CWT facility increased downstream concentrations of 

chloride and bromide above background levels. The chloride concentrations 1.7 

kilometers downstream of the treatment facility were two to ten times higher than 

chloride concentrations found in similar reference streams in western Pennsylvania. 

Radium 226 levels in stream sediments at the point of discharge were approximately	200 

times greater than upstream and background sediments. EPA intends to further study the 

frequency and magnitude of such impacts from CWTs. 

C. Impact on Surface Water Designated Uses 

UOG extraction wastewater TDS levels are high enough, if discharged untreated 

to surface water, to adversely affect a number of designated uses of surface water, 

including drinking water, aquatic life support, livestock watering, irrigation, and 

industrial use. 

 

22 Discharges from CWT facilities are subject to ELGs in 40 CFR part 437 and would not be subject to the 

proposed rule. However, the effect of discharges of treated oil and gas wastewaters from CWT facilities 

that lack high level treatment is similarly representative of POTWs. 
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1. Drinking Water Uses 

Available data indicate the levels of TDS in UOG extraction wastewaters can 

often significantly exceed recommended drinking water concentrations. Because TDS 

concentrations in drinking water sources are typically well below the recommended 

drinking water levels, few drinking water treatment facilities have technologies to remove 

TDS. Two published standards for TDS in drinking water include the U.S. Public Health 

Service recommendation and the EPA's secondary maximum contaminant level 

recommendation that TDS in drinking water should not exceed 500 mg/L. High 

concentrations of TDS in drinking water primarily degrade its taste rather than posing a 

public health risk. Typically water with less than 300 mg/L TDS is considered excellent, 

and water with TDS above 1,100 mg/L is unacceptable (DCN SGE00939). The World 

Health Organization dropped its health-based recommendations for TDS in 1993, instead 

retaining 1,000 mg/L as a secondary standard for taste (DCN SGE00947). 

The EPA also reviewed a study concerning unintentional creation of harmful 

disinfection by-products (DBPs) during POTW blending and discharge of UOG 

extraction wastewaters (DCN SGE00535; DCN SGE00587). DBPs have been shown to 

have both adverse human health and ecological affects. The study found that UOG 

extraction wastewaters contain various inorganic and organic DBP precursors that can 

react with disinfectants used by POTWs to form DBPs, particularly brominated-DBPs, 

which are suspected to be among the more toxic DBPs (DCN SGE00535). These 

precursors are a concern for drinking water managers wherever they may enter raw water 

intakes. See TDD, Chapter D.5 for further discussion of DBP formation associated with 

UOG extraction wastewaters. 
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2. Aquatic Life Support Uses 

TDS and its accompanying salinity play a primary role in the distribution and 

abundance of aquatic animal and plant communities. High levels of TDS can impact 

aquatic biota through increases in salinity, loss of osmotic balance in tissues, and toxicity 

of individual ions. Increases in salinity have been shown to cause shifts in biotic 

communities, limit biodiversity, exclude less-tolerant species and cause acute or chronic 

effects at specific life stages (DCN SGE00946). A detailed study of plant communities 

associated with irrigation drains, reported substantial changes in marsh communities 

(DCN SGE00941). When TDS increased from 270 to 1170 mg/L both coontail 

(Ceratophyllus demersum) and cattail (Typha sp.) were nearly eliminated. A related study 

found that in lakes aquatic biodiversity was lowered when salinity was high. (DCN 

SGE00940). 

It is often a specific ion concentration in TDS that is responsible for adverse 

effects to aquatic ecosystems. For example, a TDS concentration of 2,000 mg/L with 

chloride as the primary anionic constituent is acutely toxic to aquatic life, but the same 

TDS concentration composed primarily of sulfate is nontoxic. Sodium choride accounts 

for about 50 percent of the TDS typically found in UOG extraction wastewater. As 

reported in Table XI-2 (in Section XI.D.), chloride has been measured at concentrations 

up to 230,000 mg/L. Macroinvertebrates, such as fresh water shrimp and aquatic insects 

that are a primary prey of many fish species, have open circulatory systems that are 

especially sensitive to pollutants like chloride. Based on laboratory toxicity data from the 

EPA's 1988 chloride criteria document and more recent studies, invertebrate sensitivity to 

chloride acute effect concentrations ranged from 953 mg/L to 13,691 mg/L. Chronic 
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effect concentrations of chloride ranged from 489 mg/L to 556 mg/L. In addition to the 

laboratory data, the EPA also reviewed data from a 2009 Pennsylvania Department of 

Environmental Protection violation report documenting a fishkill attributed to a spill of 

diluted produced water in Hopewell Township, PA. TDS at the location of the fishkill 

was as high as 7,000 mg/L. While not related to UOG extraction wastewater, negative 

impacts of high TDS, including fish kills, were documented during 2009 at Dunkard 

Creek located in Monongalia County, Pennsylvania. (DCN SGE00001 and DCN 

SGE00001.A01) 

The EPA has published chemical-specific national recommended water quality 

criteria for some of the TDS constituents in UOG extraction wastewater, such as barium, 

chloride, manganese, and iron, based on a variety of human health or ecological 

benchmarks. A review of state and tribal water quality standards in 2012 indicated that 26 

states had adopted a numeric or narrative criterion for TDS, either for state-wide or sitespecific application (DCN SGE00945). The TDS criteria levels and the designated uses 

they are intended to protect vary greatly from state to state. For example, Alaska has a 

criterion of 1,500 mg/L TDS to protect aquatic life; Mississippi has a criterion of 750 

mg/L monthly average for protection of fish, wildlife and recreation criteria, and Illinois 

has a statewide 1,000 mg/L TDS criterion for aquatic life and a 1,500 mg/L TDS criterion 

for secondary contact recreation and indigenous aquatic life. TDS criteria adopted 

specifically for the protection of aquatic life have been developed for at least 16 of the 26 

states, some of which only apply to specific waterbodies. Oregon has the most stringent 

TDS criterion using a standard of 100 mg/L for all freshwater streams and tributaries in 

order to protect aquatic life, public water use, agriculture, and recreation. 
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3. Livestock Watering Uses 

POTW discharges to surface waters containing high concentrations of TDS may 

impact downstream uses for livestock watering. High TDS concentrations in water 

sources for livestock watering may adversely affect animal health by disrupting cellular 

osmotic and metabolic processes. Domestic livestock, such as cattle, sheep, goats, horses, 

and pigs have varying degrees of sensitivity to TDS in drinking water as shown in Table 

XIV-1. Sheep seem to be more tolerant of saline water than most domestic species but 

will only drink it if introduced to the saline water over a period of several weeks (DCN 

SGE00944). 

Table XIV-1. Tolerances of Livestock to TDS in Drinking Water 

Livestock 

Total Dissolved Solids (mg/L) 

No adverse effects on 

animals expected 

Animals may have initial 

reluctance to drink or there 

may be some scouring, but 

stock should adapt without 

loss of production 

Loss of production and a 

decline in animal condition 

and health would be 

expected. Stock may 

tolerate these levels for 

short periods if introduced 

gradually 

Beef cattle 0–4,000 4,000–5,000 5,000–10,000 

Dairy cattle 0–2,400 2,400–4,000 4,000–7,000 

Sheep 0–4,000 4,000–10,000 10,000–13,000 

Horses 0–4,000 4,000–6,000 6,000–7,000 

Pigs 0–4,000 4,000–6,000 6,000–8,000 

Poultry 0–2,000 2,000–3,000 3,000–4,000 

Source: Australia and New Zealand Water Quality Guidelines 2000. Chapter 3 Primary Industries- 9.3 Livestock 

drinking water guidelines (DCN SGE00944).

4. Irrigation Uses 

If UOG extraction wastewater discharges to POTWs increase TDS concentrations 

in receiving streams, downstream irrigation uses of that surface water may be negatively 

affected. Elevated TDS levels can limit the usefulness of water for irrigation. Excessive 

salts affect crop yield in the short term, and the soil structure in the long term. Primary 
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direct impacts of high salinity water on plant crops include physiological drought, 

increased osmotic potential of soil, specific ion toxicity, leaf burn, and nutrient uptake 

interferences (DCN SGE00938). In general, for various classes of crops the salinity 

tolerance decreases in the following order: forage crops, field crops, vegetables, fruits. 

The suitability of water for irrigation is classified using several different 

measurements, including TDS and electrical conductivity (EC). Table XIV-2. shows a 

classification of TDS concentrations for irrigation suitability. 

Table XIV-2. Permissible Limits for Classes of Irrigation Water

Class of Water 

Concentrations of TDS

Electrical Conductivitya (dS/m) TDS by gravimetric (mg/L) 

Class 1. Excellent 0.250 175 

Class 2. Good 0.250-0.750 175-275 

Class 3. Permissibleb 0.750-2.0 525-1,400 

Class 4. Doubtfulc 2.0-3.0 1.400-2,100 

Class 5. Unsuitablec 3.0 >2,100 

a = TDS (mg/L) ≈ EC (dS/m) x 640 for EC < 5 dS/m; 

b = leaching needed if used 

c = good drainage needed and sensitive plants will have difficulty obtaining stands. 

Source: AgriLife Extension (undated) (DCN SGE00936). 

In addition to short-term impacts to crop plants, irrigating with high TDS water 

can result in long-term gradual accumulation of salts or sodium in soil layers and 

eventual decrease in soil productivity. The susceptibility of soils to degradation is 

dependent on the soil type and structure. Sandy soils are less likely than finely textured 

soils to accumulate salts or sodium. Soils with a high water table or poor drainage are 

more susceptible to salt or sodium accumulation. The most common method of 

estimating the suitability of a soil for crop production is through calculation of its sodicity 
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as estimated by the soil’s sodium absorption ratio (SAR). The SAR value is calculated by 

the equation: ሾே஺శሿ

ටൣ಴ಲమశ൧൅ሾಾ೒మశሿ

2

. 

Table XIV-3. shows a general irrigation water classification system based on SAR 

values. The actual field-observed impacts, however, are very site-specific depending on 

soil and crop system (DCN SGE00938). 

Table XIV-3. General Sodium Irrigation Water Classifications

SAR Values Sodium Hazard of Water Comments 

1-9 Low Use of sodium sensitive crops must be cautioned 

10-17 Medium Amendments (such as gypsum) and leaching 

needed. 

18-25 High Generally unsuitable for continuous use 

26 or Greater Very High Generally unsuitable for use 

5. Industrial Uses 

POTW discharges to surface waters are often upstream of industrial facilities that 

withdraw surface waters for various cooling and process uses. High levels of TDS can 

adversely affect industrial applications requiring the use of water in cooling tower 

operations, boiler feed water, food processing, and electronics manufacturing. 

Concentrations of TDS above 500 mg/L result in excessive corrosivity, scaling, and 

sedimentation in water pipes, water heaters, boilers and household appliances. Depending 

on the industry, TDS in intake water may interfere with chemical processes within the 

plant. Some industries requiring ultrapure water, such as semi-conductor manufacturing 

facilities, are particularly sensitive to high TDS levels due to the treatment cost for the 

removal of TDS. 
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XV. Non-Water Quality Environmental Impacts Associated with the Proposed 

Rule 

Because the elimination or reduction of one form of pollution may create or 

aggravate other environmental problems, the EPA considers non-water quality 

environmental impacts (including energy impacts) that may result from the 

implementation of proposed regulations. The EPA evaluated the potential impact of the 

proposed pretreatment standards on air emissions, solid waste generation, and energy 

consumption. 

The proposed PSES/PSNS prohibit the discharge to POTWs of wastewater 

pollutants associated with UOG extraction. Because EPA knows of no POTWs that are 

currently accepting UOG extraction wastewater, the proposed PSES will require no 

changes in current industry wastewater management practices and, consequently, will 

have no incremental impacts on air emissions, solid waste generation, or energy 

consumption. Based on the reasoning that new sources will follow current industry 

practice, the EPA projects no incremental non-water quality environmental impacts 

associated with PSNS. 

XVI. Implementation 

A. Implementation Deadline 

Because the requirements of the proposed rule are based on current practice, the 

EPA proposes that the PSES/NSPS standards based on the regulatory options being 

proposed apply on the effective date of the final rule. 
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B. Upset and Bypass Provisions 

A “bypass” is an intentional diversion of waste streams from any portion of a 

treatment facility. An “upset” is an exceptional incident in which there is unintentional 

and temporary noncompliance with technology-based permit effluent limitations because 

of factors beyond the reasonable control of the permittee. The EPA’s regulations for 

indirect dischargers concerning bypasses and upsets are set forth at 40 CFR 403.16 and 

403.17. 

C. Variances and Modifications 

The CWA requires application of effluent limitations established pursuant to 

section 304 for direct dischargers and section 307 for all indirect dischargers. However, 

the statute provides for the modification of these national requirements in a limited 

number of circumstances. Moreover, the Agency has established administrative 

mechanisms to provide an opportunity for relief from the application of the national 

pretreatment standards for categories of existing sources. 

The EPA may develop pretreatment standards different from the otherwise 

applicable requirements for an individual existing discharger if it is fundamentally 

different with respect to factors considered in establishing the standards applicable to the 

individual discharger. Such a modification is known as a “fundamentally different 

factors” (FDF) variance. See 40 CFR 403.13. The EPA, in its initial implementation of 

the effluent guidelines program, provided for the FDF modifications in regulations. These 

were variances from the BCT effluent limitations, BAT limitations for toxic and 

nonconventional pollutants, and BPT limitations for conventional pollutants for direct 

dischargers. FDF variances for toxic pollutants were challenged judicially and ultimately 
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sustained by the Supreme Court in Chemical Manufacturers Association v. Natural 

Resources Defense Council, 479 U.S. 116, 124 (1985). FDF variances, however, are not 

available for new sources. E.I. Dupont v. Train, 430 U.S. 112, 138 (1977) 

Subsequently, in the Water Quality Act of 1987, Congress added new CWA 

section 301(n). This provision explicitly authorizes modifications of the otherwise 

applicable BAT effluent limitations or categorical pretreatment standards if a discharger 

is fundamentally different with respect to the factors specified in CWA section 304 or 

403 (other than costs) from those considered by the EPA in establishing the effluent 

limitations or pretreatment standards. CWA section 301(n) also defined the conditions 

under which the EPA may establish alternative requirements. Under section 301(n), an 

application for approval of a FDF variance must be based solely on (1) information 

submitted during rulemaking raising the factors that are fundamentally different or (2) 

information the applicant did not have an opportunity to submit. The alternate limitation 

must be no less stringent than justified by the difference and must not result in markedly 

more adverse non-water quality environmental impacts than the national limitation or 

standard. 

The EPA regulations at 40 CFR part 403, authorize the Regional Administrators 

to adjust the limits in categorical pretreatment standards and to establish alternative 

standards. The regulations further detail the substantive criteria used to evaluate FDF 

variance requests for existing discharges to POTWs. Thus, 40 CFR 403.13(d) identifies 

six factors (nature or quality of pollutants in raw wastewater, volume of wastewater, nonwater quality environmental impacts, energy requirements, age and size of a discharger’s 

facility, and cost of compliance) that may be considered in determining if a discharger is 
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fundamentally different. The Agency must determine whether, based on one or more of 

these factors, the discharger in question is fundamentally different from the dischargers 

and factors considered by the EPA in developing the nationally applicable pretreatment 

standards. The regulation at 40 CFR 403.13(e) also lists four other factors (inability to 

install equipment within the time allowed, assertion that standards cannot be achieved, 

based on other than those listed in 40 CFR 403.13(d), a discharger’s ability to pay, and 

impact of a discharge on the quality of the POTWs receiving waters) that may not 

provide a basis for an FDF variance. In addition, under 40 CFR 403.13 (c)(2), a request 

for standards less stringent than the national standard may be approved only if 

compliance with the national pretreatment standards would result in either (a) a removal 

cost wholly out of proportion to the removal cost considered during development of the 

national pretreatment standards, or (b) a non-water quality environmental impact 

(including energy requirements) fundamentally more adverse than the impact considered 

during development of the national pretreatment standards. The legislative history of 

section 301(n) underscores the necessity for the FDF variance applicant to establish 

eligibility for the variance. The EPA’s regulations at 40 CFR 403.13 are explicit in 

imposing this burden upon the applicant. The applicant must show that the factors 

relating to the discharge controlled by the applicant’s permit that are claimed to be 

fundamentally different are, in fact, fundamentally different from those factors 

considered by the EPA in establishing the applicable pretreatment standards. In practice, 

very few FDF variances have been granted for past ELGs. An FDF variance is not 

available to a new source that would be subject to PSNS. 

XVII. Statutory and Executive Order Reviews 
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A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review 

 This action is a “significant regulatory action” under the terms of Executive 

Order 12866 (58 FR 51735, October 4, 1993). Accordingly, the EPA submitted this 

action to the Office of Management and Budget (OMB) for review under Executive 

Orders 12866 and 13563 (76 FR 3821, January 21, 2011) and any changes made in 

response to OMB recommendations have been documented in the docket for this action. 

B. Paperwork Reduction Act 

This action does not impose an information collection burden under the 

provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. Burden is defined at 5 

CFR 1320.3(b). This proposal would codify current industry practice and would not 

impose any additional reporting requirements.

 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a 

regulatory flexibility analysis of any proposed rule that would be subject to notice and 

comment rulemaking requirements under the Administrative Procedure Act or any other 

statute unless the agency certifies that the rule will not have a significant economic 

impact on a substantial number of small entities. Small entities include small businesses, 

small organizations, and small governmental jurisdictions. 

For purposes of assessing the impacts of the proposed rule on small entities, small 

entity is defined as: (1) a small business that is primarily engaged in Crude Petroleum and 

Natural Gas Extraction and Natural Gas Liquid Extraction by NAICS code 211111 and 
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211112 with fewer than 500 employees (based on Small Business Administration size 

standards).

After considering the economic impacts of the proposed rule on small entities, I 

certify that this action will not have a significant economic impact on a substantial 

number of small entities. The small entities that would be subject to the requirements of 

this proposed rule are small businesses that engage in UOG extraction as defined in 

Section X. No small businesses will experience an impact because the proposed 

rulemaking does not impose any new requirement that is not already being met by the 

industry. 

D. Unfunded Mandates Reform Act 

This proposed rule does not contain a Federal mandate that may result in 

expenditures of $100 million or more for state, local, and tribal governments, in the 

aggregate, or the private sector in any one year. As explained in Section VI.C., this 

proposed rule has no costs. Thus, this proposed rule would not be subject to the 

requirements of sections 202 or 205 of the Unfunded Mandates Reform Act (UMRA). 

This proposed rule also would not be subject to the requirements of section 203 of 

UMRA because it contains no regulatory requirements that might significantly or 

uniquely affect small governments. The EPA has not identified any oil and gas facilities 

that are owned by small governments. 

E. Executive Order 13132: Federalism 

This action does not have federalism implications. It will not have substantial 

direct effects on the states, on the relationship between the national government and the 
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states, or on the distribution of power and responsibilities among the various levels of 

government, as specified in Executive Order 13132. The proposed rule would not alter 

the basic state-federal scheme established in the CWA under which the EPA authorizes 

states to carry out the NPDES permit program. The EPA expects the proposed rule 

would have little effect on the relationship between, or the distribution of power and 

responsibilities among, the federal and state governments. Thus, Executive Order 13132 

does not apply to this action. Although this order does not apply to this action, as 

explained in Section VIII., the EPA coordinated closely with states through a workgroup, 

as well as outreach efforts to pretreatment coordinators and pretreatment authorities. 

F. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments 

This action does not have tribal implications, as specified in Executive Order 

13175 (65 FR 67249, November 9, 2000). It will not have substantial direct effects on 

tribal governments, on the relationship between the Federal government and Indian 

tribes, or on the distribution of power and responsibilities between the Federal 

government and Indian tribes. The proposed rule contains no Federal mandates for tribal 

governments and does not impose any enforceable duties on tribal governments. Thus, 

Executive Order 13175 does not apply to this action. 

Although Executive Order 13175 does not apply to this action, the EPA 

coordinated with tribal officials in developing this action. The EPA coordinated with 

federally recognized tribal governments in May and June of 2014, sharing information 

about the UOG pretreatment standards proposed rulemaking with the National Tribal 

Caucus and the National Tribal Water Council. As part of this outreach effort, the EPA 
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collected data about UOG operations on tribal reservations, UOG operators that are 

affiliated with Indian tribes, and POTWs owned or operated by tribes that may accept 

industrial wastewaters (see DCN SGE00785). Based on this information, there are no 

tribes operating UOG wells that discharge wastewater to POTWs nor are there any tribes 

that own or operate POTWs that accept industrial wastewater from UOG facilities; 

therefore, this proposed rule will not impose any costs on tribes. 

G. Executive Order 13045: Protection of Children from Environmental Health and 

Safety Risks 

EO 13045 (62 FR 19885, April 23, 1997) applies to rules that are economically 

significant according to EO 12866 and involve a health or safety risk that may 

disproportionately affect children. This proposed action would not be subject to EO 

13045 because it is estimated to cost less than $100 million and does not involve a safety 

or health risk that may have disproportionately negative effects on children. 

H. Executive Order 13211: Energy Effects 

This proposed action is not subject to Executive Order 13211, because it not a 

“significant energy action” as defined in Executive Order 13211, “Actions Concerning 

Regulations That Significantly Affect Energy Supply, Distribution, or Use” (66 FR 

28355, May 22, 2001). This action will not have a significant adverse effect on the 

supply, distribution, or use of energy, as described in Section XV. of the proposed rule. 

I. National Technology Transfer Advancement Act 

Section 12(d) of the National Technology Transfer and Advancement Act of 1995 

(“NTTAA”), Public Law No. 104-113, 12(d) (15 U.S.C. 272 note) directs the EPA to use 
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voluntary consensus standards in its regulatory activities unless to do so would be 

inconsistent with applicable law or otherwise impractical. Voluntary consensus standards 

are technical standards (e.g., materials specifications, test methods, sampling procedures, 

and business practices) that are developed or adopted by voluntary consensus standards 

bodies. NTTAA directs the EPA to provide Congress, through OMB, explanations when 

the Agency decides not to use available and applicable voluntary consensus standards. 

This proposed rulemaking does not involve technical standards. Therefore, the 

EPA is not considering the use of any voluntary consensus standards. 

J. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations 

Executive Order 12898 (59 FR 7629 (Feb. 16, 1994)) establishes federal 

executive policy on environmental justice. Its main provision directs federal agencies, to 

the greatest extent practicable and permitted by law, to make environmental justice part 

of their mission by identifying and addressing, as appropriate, disproportionately high 

and adverse human health or environmental effects of their programs, policies, and 

activities on minority populations and low-income populations in the United States. 

The EPA determined that this proposed rule will not have disproportionately high 

and adverse human health or environmental effects on minority or low-income 

populations because it does not affect the level of protection provided to human health or 

the environment. The proposed rule changes the control technology required but will 

neither increase nor decrease environmental protection (as described in Section VI.C.).
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The EPA welcomes comments on this aspect of the proposed rulemaking and, 

specifically, invites the public to identify potential environmental justice considerations 

associated with this proposed regulation.
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List of Subjects in 40 CFR Part 435 

Environmental protection, Pretreatment, Waste treatment and disposal, Water pollution 

control, Unconventional oil and gas extraction. 

Dated: 

____________________________ 

Gina McCarthy, 

Administrator. 
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Therefore, it is proposed that 40 CFR part 435 be amended as follows: 

PART 435—OIL AND GAS EXTRACTION POINT SOURCE CATEGORY 

1. The authority citation for part 435 continues to read as follows: 

Authority: The Clean Water Act, 33 U.S.C. 1251, 1311, 1314, 1316, 1317, 1318, 

1342 and 1361. 

2. Add §435.33 to read as follows: 

§435.33 Pretreatment standards of performance for existing sources (PSES). 

(a) PSES for Wastewater from Conventional Oil and Gas Extraction. [Reserved] 

(b) PSES for Wastewater from Unconventional Oil and Gas Extraction. Except as 

provided in 40 CFR 403.7 and 403.13, any existing source subject to this section, must 

achieve the following pretreatment standards for existing sources (PSES). 

(1) There shall be no discharge of wastewater pollutants associated with 

production, field exploration, drilling, well completion, or well treatment for 

unconventional oil and gas extraction (e.g., drilling muds, drill cuttings, produced sand, 

produced water) into publicly owned treatment works. 

(2) For the purposes of this section, 

(i) Unconventional oil and gas means crude oil and natural gas produced by a 

well drilled into a low porosity, low permeability formation (including, but not limited to, 

shale gas, shale oil, tight gas, tight oil). 

(ii) Drill cuttings means the particles generated by drilling into subsurface 

geologic formations and carried out from the wellbore with the drilling fluid. 

(iii) Drilling muds means the circulating fluid (mud) used in the rotary drilling of 

wells to clean and condition the hole and to counterbalance formation pressure. 
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(iv) Produced sand means the slurried particles used in hydraulic fracturing, the 

accumulated formation sands, and scales particles generated during production. Produced 

sand also includes desander discharge from the produced water waste stream, and 

blowdown of the water phase from the produced water treating system. 

(v) Produced water means the water (brine) brought up from the hydrocarbonbearing strata during the extraction of oil and gas, and can include formation water, 

injection water, and any chemicals added downhole or during the oil/water separation 

process. 

3. Add §435.34 to read as follows: 

§435.34 Pretreatment standards of performance for new sources (PSNS). 

(a) PSNS for Wastewater from Conventional Oil and Gas Extraction. [Reserved] 

(b) PSNS for Wastewater from Unconventional Oil and Gas Extraction. Except as 

provided in 40 CFR 403.7 and 403.13, any new source with discharges subject to this 

section must achieve the following pretreatment standards for new sources (PSNS). 

(1) There shall be no discharge of wastewater pollutants associated with 

production, field exploration, drilling, well completion, or well treatment for 

unconventional oil and gas extraction (e.g. drilling muds, drill cuttings, produced sand, 

produced water) into publicly owned treatment works. 

(2) For the purposes of this section, the definitions of unconventional oil and gas, 

drill cuttings drilling muds, produced sand, and produced water are as specified in 

§435.33(b)(2)(i) through (b)(2)(v). 

4. Add subpart H to read as follows: 

Subpart H—Coalbed Methane Subcategory [Reserved]