0

Overview of Hydraulic Fracturing 

Wastewater Research

Technical Workshop Series: 

Wastewater Treatment and Related Modeling

Cynthia Sonich-Mullin & Christopher A. Impellitteri

EPA-Research Triangle Park • April 18, 2013
1

EPA Study of the Potential Impacts of 

Hydraulic Fracturing on Drinking Water 

Resources

EPA Study Goals:

• Assess the potential impacts of 

hydraulic fracturing on drinking water 

resources

• Identify the driving factors that affect 

the severity and frequency of any 

impacts

For more information: http://www.epa.gov/hfstudy
2

Hydraulic Fracturing Water Cycle

WATER CYCLE STAGES

Water Acquisition → Chemical Mixing → Well Injection → 

Flowback and Produced Water → Wastewater Treatment and Waste Disposal 

Water Acquisition

Chemical 

Mixing

Well Injection

Flowback and 

Produced Water

Wastewater Treatment and 

Waste Disposal

Surface

Water

Ground

Water

Wellhead

Recycling Facility

Disposal

Wastewater Well

Treatment Plant
3 

Primary Research Questions

Water Treatment and

Waste Disposal

Water Acquisition

Chemical Mixing

Flowback and

Produced Water

Well Injection

How might large volume water withdrawals from ground 

and surface water impact drinking water resources?

What are the possible impacts of releases of flowback

and produced water on drinking water resources?

What are the possible impacts of the injection and 

fracturing process on drinking water resources?

What are the possible impacts of releases of hydraulic 

fracturing fluids on drinking water resources? 

What are the possible impacts of inadequate treatment of 

hydraulic fracturing wastewaters on drinking

water resources?

Research Questions
4 

What are the potential impacts 

from surface water disposal of 

treated hydraulic fracturing 

wastewater on drinking water 

treatment facilities?

What are the common treatment 

and disposal methods for 

hydraulic fracturing wastewater 

and where are these methods 

practiced?

How effective are conventional 

POTWs and commercial 

treatment systems in removing 

organic and inorganic 

contaminants of concern in 

hydraulic fracturing wastewater?

Literature Review

Wastewater Treatability Studies

Literature Review

Well File Review

FracFocus Analysis 

Literature Review

Surface Water Modeling

Source Apportionment Studies

Brominated Disinfection By-Product Precursor Studies

Secondary Research Questions Research Projects

Secondary Research Questions
5

Types of Research Projects

Analysis of 

Existing Data

Literature 

Review

Spills Database 

Analysis

Service 

Company 

Analysis

Well File 

Review

FracFocus

Analysis

Scenario 

Evaluations

Subsurface 

Migration 

Modeling

Surface Water 

Modeling

Water 

Availability 

Modeling

Laboratory 

Studies

Source 

Apportionment 

Studies

Wastewater 

Treatability 

Studies

Brominated 

Disinfection ByProduct Studies

Analytical 

Method 

Development

Toxicity 

Assessment

Case 

Studies

Retrospective 

Case Studies

Prospective 

Case Studies

4/18/2013
6

Objective: Collect information on wastewater treatment and 

disposal from hydraulic fracturing operations to inform project 

plans and interpretations of results 

Literature Review

Analysis of Existing Data

Research Progress

• Evaluate information on wastewater treatment and disposal 

from hydraulic fracturing operations from existing papers and 

reports, focusing on peer-reviewed literature

• Follow procedures identified in study plan

Next Step

• Continue to review and assess literature related to wastewater 

treatment and disposal according to research questions in the 

study plan
7

Objective: Assess well construction and hydraulic fracturing 

operations as reported by nine oil and gas operators

Research Progress

• Well-specific records:

o Provided by nine oil and gas operators (includes 

confidential business information)

o Includes hydraulic fracturing wastewater treatment and 

disposal practices for 332 wells hydraulically fractured in 

2009 and 2010 

• Extraction of available data from the well files is underway

Next Steps

• Work with oil and gas operators to clarify information provided

• Analyze data to address research questions

Well File Review

Analysis of Existing Data
8

Objective: Collect information on water volumes and sources 

as reported by oil and gas companies

Research Progress

• Extracted data, checked for quality issues, and organized in 

a database for analysis

• Developed draft queries to address research questions

Next Steps

• Analyze water usage

• Summarize data by water source or type

FracFocus Analysis

Analysis of Existing Data
9

Wastewater Treatability

Laboratory Studies

Commercial Treatment Systems

• Field studies

• Collect influent, effluent, and 

residuals samples

• Analyze concentrations of VOCs, 

SVOCs, anions, 

metals/inorganics, TDS, 

radionuclides

Wastewater Treatment 

Facility/Biological Processes

• Bench studies with chemostat

reactors

• Blend hydraulic fracturing 

wastewater with synthetic 

municipal wastewater

• Collect influent and effluent 

samples

• Monitor effects on biological 

processes within wastewater

Objective: Assess effectiveness of wastewater treatment processes on 

selected chemicals found in hydraulic fracturing wastewater
10

Objective: Identify possible concentrations of selected chemicals at 

public water system intakes downstream from wastewater treatment 

facilities

• Collect model inputs from the National Pollutant Discharge 

Elimination System monitoring reports and USGS stream water 

quality and flow rate data

• Use three modeling approaches to determine potential bromide 

and radium levels downstream

1) Steady-state mass balance model

2) Transient empirical model

3) Hybrid empirical-numerical model

• Run models with different discharge scenarios and stream flow 

scenarios based on data collected

Surface Water Modeling

Scenario Evaluations

Monte Carlo simulation used to 

estimate uncertainty in output

Confirm results with USGS 

tracer data and EPA Water 

Quality Simulation Package
11

Objective: Identify proportion of hydraulic fracturing wastewater that 

may impact public water system intakes downstream from wastewater 

treatment facilities

Source Apportionment

Laboratory Studies

Sample Analyses

• Field studies on two rivers

• Collect samples upstream and 

various distances downstream from 

discharge

• Analyze samples for suite of 

elements and ions including 

strontium 87/86 ratios

Modeling

• Compare two rivers using peerreviewed models

• Identify and quantify contaminant 

source types using receptor 

models

• Receptor models include Unmix, 

Positive Matrix Factorization, 

Chemical Mass Balance
12

Sample Drinking Water Intake

Discharge Point

Discharge includes hydraulic 

fracturing wastewater, coalfired power plant effluents, 

mining effluent, and road salt 

Sample Upstream

ISCO Sampler

Sample Downstream

Sample Discharge

Source Apportionment

Laboratory Studies
13

Total Trihalomethanes

• Focus on the formation of brominated trihalomethanes

• Bench studies

• Compare equimolar concentrations of bromide in spiked laboratory 

water and blended effluents

• Maintain chloride:bromide ratio found in effluents in spiked waters

• Eliminate chloride:bromide ratio as a variable

Brominated Disinfection ByProduct Precursor Studies

Laboratory Studies

Objective: Assess the contribution of hydraulic fracturing 

wastewater to formation of brominated disinfection by-products at 

public water systems
14

Discussion

Are there other sources of data and/or samples which 

could be obtained for further study?

What are the most important future research topics 

regarding wastewater management and water reuse?