Evaluation of Potential Impacts of Hydraulic Fracturing

Flowback Fluid Additives on Microbial Processes in

Publicly-Owned Treatment Works (Po-rvvs)

Prepared for

Halliburton Energy Services, Inc. (HESI)

P.O. Box 42806

Houston, TX 77242-2806

December 31,2009

~ -~ Grad=ent

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Table of Contents

1 Introduction .............................................................................................................. 1

2

3

Hydraulic Fracturing Flowback Fluid Disposal to a POTW .................................... 2

Assessment of Potential Impacts of Hydraulic Fracturing Flowback Fluid

Additives on POTW Biological Processes ............................................................... 3

3.1 Exposure Analysis .............................................................................................................. 3

3.2 Effects Analysis .................................................................................................................. 4

3.3 Risk Characterization .......................................................................................................... 5

4 Conclusion ................................................................................................................ 6

References ........................................................................................................................... 7

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List of Tables

Table 1

Table 2

Table 3

HF Flowback Disposal to a POTW - Operational Assumptions

HF Flowback Disposal - Acute Risks to Microorganisms Based on Model dSGEIS Fluid

Concentrations

HF Flowback Disposal - Acute Risks to Microorganisms Based on Measured Flowback

Fluid Concentrations from PA and WV

List of Abbreviations

BOD

dSGEIS

HESI

HF

I~Q

MGD

NYSDEC

PA

POTW

QSAR

RBC

SPDES

TSS

Biochemical Oxygen Demand

Draft Supplemental Genetic Environmental Impact Statement

Halliburton Energy Services, Inc.

Hydraulic Fracturing

Hazard Quotient

Million Gallons Per Day

New York State Department of Environmental Conservation

Pennsylvania

Publicly-owned Treatment Works

Quantitative Structure-Activity Relationship

Risk-Based Concentration

State Pollutant Discharge Elimination System

Total Suspended Solids

West Virginia

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1 Introduction

The New York State Department of Environmental Conservation (NYSDEC) published a Draft

Supplemental Generic Environmental Impact Statement (dSGEIS), dated September 2009, which contains

generic permit requirements for the development of natural gas production wells in the Marcellus Shale

formation using horizontal drilling and high-volume hydraulic fracturing techniques (NYSDEC, 2009).

This memorandum evaluates potential risks of upsetting microbial processes in a wastewater treatment

plant from exposure to typical additives likely to be present in hydraulic fracturing (HF) flowback fluid.

Gradient has prepared this report on behalf of Halliburton Energy Services, Inc. (HESI).

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2 Hydraulic Fracturing Flowback Fluid Disposal to a POTW

Several options exist or are being developed for treatment, recycling or reuse of flowback water

generated during HF operations.1 One option is treatment of flowback water at publicly-owned treatment

works (POTWs), which typically discharge effluent to surface waters, and are regulated in New York

State by the State Pollutant Discharge Elimination System, commonly referred to as SPDES. The

POTW’s permit defines whether it can accept non-domestic waste and includes specific discharge

limitations and monitoring requirements. A POTW must have a State-approved "pretreatment" program

in order to accept industrial wastewater (such as HF flowback water). POTWs must also notify NYSDEC

of any new industrial waste or of substantial changes in the volume or character of pollutants they plan to

receive at their facility. NYSDEC must then determine if the SPDES permit needs to be modified.

In addition to an approved pretreatment program, a headworks analysis is required for a POTW to

be able to accept HF flowback water. The data required for conducting a headworks analysis are

specified in the dSGEIS (pp. 7-58 and 7-59) and include: general chemistry and aquatic toxicity. The

POTW will utilize these data to determine whether the volumes and concentrations of chemicals present

in the HF flowback water can be accepted by the facility and the changes needed to the facility’s permit.

One of the key objectives of a headworks analysis is to determine whether HF additives could adversely

affect the POTW’s microorganisms resulting in disruption of the POTW operation and diminished

effluent quality. Therefore, this report presents such an analysis to predict the likely impact of HF

additives in flowback water, if any, on microorganisms at a POTW.

1 Information summarized in Section 2 of this memo is based upon information presented in the dSGEIS (NYSDEC, 2009).

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3 Assessment of Potential Impacts of Hydraulic Fracturing Flowback

Fluid Additives on POTW Biological Processes

Typically, microorganisms are used in the secondary treatment of wastewater to decompose

organic matter at a POTW. As such, conditions in this secondary (biological) wastewater treatment step

need to be conducive to microorganism survival. Failure to meet such conditions can cause an upset of

the wastewater treatment process and can result in effluents that are not sufficiently treated for discharge

to surface water.

3.1 Exposure Analysis

As discussed in Section 2, POTWs operate under permitting programs to ensure that upset

conditions and discharges of inadequately treated wastewater are avoided under typical conditions. To

evaluate the risk of flowback fluid from Marcellus Shale hydraulic fracturing operations causing

disruption of POTW biological treatment processes, we used typical HF operations described in the

dSGEIS, and operational information provided by HESI to Gradient, and assessed the potential impacts

on POTW microorganisms for the operating conditions listed in Table 1.

Table 1

HF Flowback Disposal to a POTW - Operational Assumptions

POTW Treatment

HF Disposal (gal!tmck) 5,000

Transportation Rate (tmcks/day) 10

Disposal Rate (gal/day) 50,000

POTW Flow (gal/day) 2,000,000[a]

Flowback Fluid Dilution in POTW 40 (disposal rate/POTW flow)

Notes:

[4 Median POTW design flow for POTWs listed in Appendix 21 of the dSGEIS.

Based on the list of POTWs permitted to accept industrial wastewater listed in the dSGEIS, the

median POTW flow capacity among these POTWs is 2 million gallons per day (MGD) (see Appendix 21

dSGEIS). It is anticipated that a typical HF flowback disposal rate could be 50,000 gal/day, resulting in a

40-fold dilution of the HF flowback fluid with other influent water. To calculate exposure concentrations

to which microorganisms in a typical wastewater treatment plant would be exposed, the 40-fold dilution

factor was applied to:

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Maximum selected representative pollutant concentrations for the model HF fluid listed in Table

6.13 of the dSGEIS (dSGEIS model HF fluid); and

Maximum measured flowback constituent concentrations,2 based on limited data from

Pennsylvania and West Virginia listed in Table 6.2, dSGEIS.3

POTW microorganism exposure concentrations for the dSGEIS model HF fluid are presented in

Table 2 and exposure concentrations for the flowback fluid based on PA and WV data are presented in

Table 3. These exposure concentrations were compared to microbial toxicity effect concentrations to

characterize potential risks for disruption of biological treatment processes at a typical POTW.

3.2 Effects Analysis

Traditionally, municipal wastes have been mineralized biologically, employing an assortment of

microorganisms. These wastes normally contain readily biodegradable organic substances, however with

rapid industrialization, certain synthetic organic chemicals have been shown to cause upset conditions and

POTW permit violations. Microbial toxicity data for synthetic organic chemicals are limited.

Nonetheless, measured toxicity data were found for three (3) out of the 13 chemicals listed in the dSGEIS

HF model fluid (Table 2), and all four (4) synthetic organic chemicals measured in flowback fluid from

PA and WV (Table 3). The lowest median inhibitory concentration (IC50),4 reported in Trevizo and

Nirmalakhandan (1999) or Nirmalakhandan et al. (1994), to have an effect on activated sludge,

methanogens, nitrobacteria, or two commercial cultures (Polytox and Microtox) was used as the effects

concentration [Risk-Based Concentration (RBC)] for POTW microorganisms.

With advances in quantitative structure-activity relationships (QSARs) it has become increasingly

possible to derive models using available test results that can reliably predict toxicity for chemicals

lacking effects data. For example, aqueous solubility was shown to be a reliable predictor of microbial

toxicity by Trevizo and Nirmalakhandan (1999). These authors demonstrated statistically significant

correlations between experimental toxicity data [(log (IC50)] and experimental water solubility data [log

(solubility)]. An overall correlation was found to be:

2 Constituent concentration estimates based on < 3 measurements were not considered sufficiently robust and were not further

retained in our analysis. 3 As stated in the dSGEIS, characteristics of flowback fluid from the Marcellus shale in New- York are expected to be similar to

flowback from PA and WV, but not identical (NYSDEC, 2009).

4 IC50 (the median inhibitory concentration): This is a measure of the effectiveness of a chemical in inhibiting biological or

biochemical function. For instance, in the Microtox assay, it is the concentration of a chemical at which 50% reduction in

bioluminescence by marine bacteria occurs.

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log (IC50, mM/l) 0.68 log (Solubility, mM/l) - 0.25

with a correlation coefficient of 0.756 for nearly 200 data points. This correlation was used to predict

microbial toxicity values (RBC) for the remaining organic chemicals in the dSGEIS model HF fluid.

3.3 Risk Characterization

The risk characterization for our analysis is presented as an HQ, or hazard quotient, relating the

estimated HF flowback constituent concentrations in a typical POTW to the chemical’s risk-based

concentration, or RBC:

POTW Conc

HQ= RBC

The numerator of this equation (POTW Conc) was calculated using the dSGEIS HF model fluid

or measured flowback data (from PA and WV) and applying a dilution factor of 40. The denominator of

this equation is the risk-based concentrations that were derived in the previous section. An HQ value of

less than 1 indicates that adverse effects on POTW microorganisms are unlikely.

Since all predicted HQs are substantially lower than 1 (Table 2), none of the synthetic organic

constituents in the dSGEIS model HF fluid are present at concentrations that are expected to adversely

impact biological treatment processes at a typical POTW. Similarly, measured concentrations in HF

flowback fluid from PA and WV, after dilution at a typical POTW are more than 3 orders of magnitude

below microbial effect concentrations and are therefore not expected to upset plant treatment processes

(Table 3).

There are a number of additional constituents listed in Table 3, such as conventional pollutant

parameters [e.g., biochemical oxygen demand (BOD), pH, total suspended solids (TSS), oil & grease,

etc. ] and non-conventional parameters (e.g., metals). These additional constituents are commonly treated

at POTWs and regulated under the SPDES permitting program to ensure compliance with applicable

statutory and regulatory requirements. Therefore, these parameters are not expected to cause microbial

toxicity and disrupt biological treatment processes under the conditions specified in a typical POTW

facility’s permit.

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4 Conclusion

We evaluated potential risks of upsetting microbial processes in a wastewater treatment plant

from exposure to typical organic additives likely to be present in Marcellus Shale HF flowback fluid. Our

analysis demonstrates that organic additives in the dSGEIS HF model fluid and measured flowback fluid

data from PA/WV are not expected to cause microbial toxicity and upset conditions at POTWs that would

treat such discharges in New York. Conventional (e.g., BOD, pH, TSS, oil & grease, etc.) and nonconventional pollutants (e.g., metals) present in HF flowback fluid are commonly treated at POTWs and

regulated under the SPDES permitting program to ensure compliance with applicable statutory and

regulatory requirements using pre-treatment approaches. They are therefore not expected to cause

microbial toxicity and disrupt biological treatment processes under the conditions specified in the

POTW’s permit. Based on the analysis presented herein, it can be concluded that the organic HF fluid

additives listed in the dSGEIS (both in the dSGEIS HF model fluid and in measured flowback data) are

present at concentrations substantially below those that might result in disruption of biological treatment

processes at typical POTWs treating HF flowback fluids in New York and therefore the possibility that

these HF fluid additives might cause an upset condition is de minimis.

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References

New York State, Dept. of Environmental Conservation (NYSDEC). 2009. "Well Permit Issuance for

Horizontal Drilling and High-Volume Hydraulic Fracturing to Develop the Marcellus Shale and other

Low-Permeability Gas Reservoirs (Draft)." Division of Mineral Resources, Bureau of Oil & Gas

Regulation / Supplemental Generic Environmental Impact Statement on the Oil, Gas and Solution Mining

Regulatory Program. September.

Nirmalakhandan, N; Arulgnanendran, V; Mohsin, M; Sun, B; Cadena, F. 1994. "Toxicity of mixtures or

organic chemicals to microorganisms." Water Research 28(3):543-551.

Trevizo, C; Nirmalakhandan, N. 1999. "Prediction of microbial toxicity of industrial organic chemicals."

Water Science and Technology 39(10-11):63-69.

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