The Impact of Commercially Treated Oil and Gas Produced Water Discharges on Bromide Concentration s and Modeled Brominated Trihalomethane Disinfection Byproducts at two Downstream Municipal Drinking Water Plants in the Upper Allegheny River , Pennsylvania, U SA
Matthew S. Landis , * Ali S. Kamal § , Kasey D. Kovalcik , Carry Croghan, Gary A. Norris US EPA, Office of Research and Development, Research Triangle Park, NC 27709 Amy Bergdale US EPA Region 3 , Office of Monitoring and Assessment , Wheeling , WV 26003

* C orresponding author phone: (919) 541

- 4841; landis.matthew@epa.gov
§ Now at EPA Office of Air Quality Planning and Standards, Research Triangle Park, NC 27709
Abstract In 2010, a dramatic increase in the level s of total trihalomethane (THM) and the relative prop ortion of brominated species was observed in finished water at several Western Pennsylvania water utilities (P D W ) using the Allegheny River as their raw water supply

. A n increase in bromide concentratio ns in the Allegheny River was implicated to be the cause of the elevated water disinfection byproducts. This study focused on quantify ing t he contribution of bromide from a commercial wastewater treatment facility (CWTF) that solely treats wastes from oil and ga s producers and discharge s in to the upper reaches of the Allegheny River , and its impact on two downstream PDW s
. In 2012, automated daily integrated samples were collected on the u pper reaches of the Allegheny River at six sites during t h ree season al two

- week sampling campaign s to characterize bromide concentrations and river dispersion characteristics during periods of high (>8500 m 3 min - 1 ) and low (<8500 m 3 min - 1 ) river discharge levels

. The CWTF discharge resulted in significant increases in bro mide compared to upst ream baseline values in PDW raw drinking water intake s during periods of low river discharge

. During high river discharge , t he assimilative dilution capacity of the river resulted in lower absolute halide concentrations , bu t signi fica nt elevations bromide concentrations were still observed at the nearest downstream PDW intake over baseline river levels . On days with active CWTF effluent discharge the magnitude of bromide impact increased by 39 ppb (53%) and 7 ppb (22%) for low and hig h river discharge campaigns, respectively

. Despite a general declining trend in Allegheny River bromide (2009

- 2014) , a significant impact of discharges from CWTF and coal

- fired power plants to bromide concentrations during the low river discharge regime a t downstream PDWintakes was observed , resulting in a small modeled increase in total THM ( 3%), and an estimated positive shift (41

- 47 %) to more toxic brominated THM analogs. Keywords: Specific Conductivity, Source Attribution.Introduction Elevated bromid e (Br - ) levels in source water can lead to the formation of higher levels of brominated disinfection byproducts (DBP) in finished drinking water ; currently, c onventional drinking water treatment processes do not effectively remove Br - from source water ( St ates et al., 2013 )

. In 2010 the Pittsburg h Water and Sewer Authority (PWSA) observed significantly increased concentrations of total trihalomethanes (THM; a group of regulated DBP s) in their water distribution system that were near the regulatory limit of 80 ppb ( U.S. EPA, 1998 ) , and found the proportion of brominated THM species to be substantially higher than normal ( States et al., 2013 ). Six additional drinking water companies relying on the Allegheny River as their source of raw water had their finish ed water tested and elevated levels of total and brominated THM concentrations were also found , suggesting that the concentration and chemical makeup of the THMs were changing in response to increased Br - concentrations in the river source water ( States et al., 2013 )

. Brominated DBPs are of particular concern to public health authorities since they are more carcinogenic, cytotoxic, and genotoxic than their chlorinated DBP analogs ( WHO, 2000; Plewa et al., 2002; Richardson et al., 2007 ) , from consumption , i nhalation during showering, and dermal exposure ( Cantor et al., 2010; Font

- Ribera et al., 2010; Kogevinas et al., 2010; Richardson et al., 2010 ). Discharges of treated oil and gas well produced wastewater an d commercial coal

- fired power plants have been i mplicated as the primary source s of excess Br - in both the Allegheny and Monongahela rivers in Western Pennsylvania ( States et al., 2013; Warner et al., 2013; Wilson and VanBriesen, 2013 )

. Naturally occurring brine in the hydrocarbon rich formations in th e Appalachian Plateau in Western Pennsylvania leads to elevated Br - and chloride (Cl - ) concentrations in the oil and gas produced wastewater ( Dre sel and Rose, 2010; Haluszczak et al., 2013 ). These elevated levels of Br - and Cl - being dischar ged into the A llegheny River have raised concerns of many Western Pennsylvania water suppliers over their ability to comply with the U.S. Environmental Protection Agency ( EPA ) Stage 2 Disinfectant/Disinfection Byproduct Rule (2006) amend ing the samplin g and quarterly DB P calculation methodologies with compliance beginning in 2012 for the largest systems

.
T he large national increase in exploration, drilling, and production of oil and gas from non

conventional shale resources has generated large volumes of additional wast ewater that ultimately needs to be reused/recycled or disposed ( Kargbo et al., 2010; Gregory et al., 2011;Vidic et al., 2013 )

. M ost oil and gas well wastewater is disposed through deep well injection i n many parts of the U.S

. (Gregory et al., 2011). How ever, i n Pennsylvania , there is currently a limited capacity for deep well injection with only eight EPA approved Class II D brine disposal wells , and th e development of the Marcellus S hale has increased the total wastewater generated in the region by ~570% since 2004 (Lutz et al., 2013). T he majority of oil and gas well wastewater that is not reused is either trucked out of state for deep brine disposal well injection

or disposed of using alternative methods ( Veil, 2010; Wilson and VanBriesen, 2013 )

.

In P ennsylvania , the first Marcellus Shale gas well was drilled in 2004 ( PA DCNR, 2014 ). Through March 9, 2012 the Pennsylvania Department of Conservation and Natural Resources issued 11,772 permits for non

- conventional wells in the Marcellus Shale , of which 1,456 well completion reports were received ( PA DCNR, 2014 )

. Overall, the number of gas producing wells increased in Pennsylvania from 46,654 in 2005 to 55,136 in 2012 ( U.S. EIA, 2014 )

. Historically, Pennsylvania has allowed oil and gas produced wastewat er to be discharged into public ly owned se wage treatment works (POTWs) where it was diluted , or treated by commercial wastewater treatment facilities (CWTF) that solely treat wastes from oil and ga s producers wit h subsequent discharge to surface waters ( Ve il, 2010; Lutz et al., 2013 )

. Most CWTFs are designed to chemically precipitate, flocculate , and filter solids ; but are not designed

nor successful in removing dissolved monovalent halides like Br - and Cl - ( Ferrar et al., 2013; Warner et al., 2013 ). In 2 011 the Pennsylvania Department of Environmental Protection (PADEP) issued a letter to oil and gas producers requesting that they voluntarily d isco ntinu e using POTWs and CWTFs to dispose of Marcellus formation wastewaters ( PA DEP, 2011 ) , which accounted fo r 79% of gas

- related wastewater in Pennsylvania that year ( Vidic et al., 2013 )

. A ll indications suggest that the pro duc ers have complied and diverted Ma r cellus derived wastewater to other reuse or disposal options ( Wilson and VanBriesen, 2013 ) . However, other

non - Marcellus Devonian unit oil and gas wastewaters continue to be sent to both POTWs and CWTFs that ultimately discharge to surface waters (Vengosh et al., 2014; U

. S

. EPA 2015) . The concentration s of Br - and Cl - in the upper Devonian well brines ha ve been reported to be as high

or higher than the Marcellus wastewater ( Dre sel and Rose, 2010; Warner et al., 2013 )

. The Allegheny River is a vital natural re source to residents of Western Pennsylvania. Among itsprovisioning services are accepting waste discharge and supplying drinking water. There is a delicate balance between these services , especially during low river discharge periods when the river ’ s assimilative capacity to dilute contaminant concentrations down to safe levels is diminished ( Ferra r et al., 2013 )

. The Allegheny watershed is vulnerable to impairment due to current dis charges from POTWs, CWTFs, coal

- fired power plants , iron and steel production, manufacturing, urban runoff, roadway deicing materials, ongoing coal mining activities, l egacy mine discharges, and acid rain ( Schofield 1982; PA DEP 2002; Wilson and VanBriesen, 2013 ). The water quality at the intakes for p ublic drinking water systems (P DW ) is degraded by these upstream discharge source s , and c oncern over this balance is hei ghtened due to perceived impacts from increased oil and gas drilling activities ( States et al., 2013 )

. Many of the sources of impairment to river water quality have distinctive chemical characteristics, discharge at different spatial locations, and are va riable in time (U.S. EPA 2015). To manage these valuable watershed services, investigative tools and strategies that exploit these unique discharge properties are needed that track and quantitatively apportion discharge source impacts on surface water qua lity.
This study ’s goal s were to (i) establish an approach whereby the impact of a surface water discharge from a CWTF in the upper reaches of the Allegheny river on the raw water halide concentrations at the nearest downstream PDW could be quantitatively evaluated , and (ii) to estimate the impact of CWTF discharges on total THM concentrations and the relative abundance of brominated DBPs in finished drinking water at two PDWs on the Allegheny Riv er using empirical EPA models.

Methods Study Design In 2012 , U.S. EPA conducted three seasonal two

- week sampling campaigns : s pring ( April 30

- May 14 ), summer ( July 5

- 19 ), and fall ( September 19

- October 4 ) o n the u pper Allegheny River in Pennsylvania

. Samples were simultaneously collected from a n upstream location (S01

- Upstream ), a C WTF discharge (S02

- CWTF ), two downstream locations (S03

- Downstream1 & S04

- Downstream2 ) , and two downstream PDW raw water intakes ( S05

- PDW1 & S06

- PDW2 ; Figure 1 ) using automated samplers . The CWTF was accepting, treating, and dischargin g non Marcellus Appalachian Plateau Devonian strata oil and gas produced wastewater during allsampling campaigns

. The upstream sampling location was to establish “baseline ” conditions into the study domain , and the multiple downstream sampling locations were to evaluate transport and dispersion of inorganic species discharged by the CWTF to the closest downstream PDW

. The Allegheny River mile of each site and their relative distance from the CWTF discharge is presented in Appendix A. 1

. The f irst sampler downstream of the C W TF discharge

wa s located ~12 km downstream to allow for adequate initial mixing of the e ffluent and river water

. The second downstream sampler wa s located between the first downstream sampling locat ion and the closest P D W intake , and was located ~15 km downstream of an 85 megawatt bituminous waste coal

- fired power plant discharge

. The second PDW plant was included to investigate the general trend of increasing Br - concentrations in the Allegheny as it travers es from the u pper into the lower reaches of river

.
Allegheny River The Allegheny River drains a catchm ent area of approximately 30,300 km 2 in the Penn sylvania and New York region of the northwestern Appalachian Plateau (PA F ish and B oat C ommission , 2011 ). Most reaches of the u ppe r Allegheny flow o ver locally

- derived river sediment overlying thick layers of glacial outwash (sand and gravel). The Allegheny headwaters flow in to the Allegheny Reservoir and leaves via the Kinzua Dam. Approxi mately 203 k m of the Allegheny River downst ream of the Kinzua Dam , including the entire upper Allegheny study domain (S01

- Upstream to S05

- PDW1), remains free

- flowing ; and is confined within a narrow, severely meandering valley with precipitous side slopes ( PA FBC, 2011).

Further downstream, the Al legheny is impounded and regulated by the U.S. Army Corp of Engineers (USACE)

. The USACE manages the water level of the Allegheny in the study domain by controlling water di scharge volumes from the Kinzua , Tionesta, Union City, and Woodcock reservoirs ( US ACE, 2014 ) . This active management provides for flood control, water quality management, and downstream navigation requirements

. The water level s in the

u pper reaches of the Allegheny River below the Kinzua Dam have historically been (i) highest in the l ate fall and winter during reservoir drawdown in preparation for snow melt and spring precipitation , resulting in a relatively high assimilative capacity from source discharges, and (ii) lowest in the summer res ulting in elevated concentrations of contamin ants ( USGS, 1993; U SGS,2013 )

. Due to the resulting annual bimodal nature of Allegheny River water discharge rates, our data analysis is categorized into “high” (≥ 85 00 m 3 min - 1 ) and “low” discharge (< 8500 m 3 min - 1 ) regimes (USGS, 1993)

.
Sample Collection Teledyne Isco (Lincoln, NE) Model 6712 computer

- controlled a utomatic s equential w ater
s ampler s were utilized to simultaneously collect daily 800 ml composite ri ver, CW T F , and PDW samples along the Allegheny River study domain. Acid

- cleaned ( L andis and Keeler, 1997) polypropylene bottles and T eflon sampling line were used to minimize conta mination from the sampler

. The samplers were programmed to collect 400 ml twice a day at 0 9:00 and 12 :00 EST, after automatically rinsin g the sampling line three times . The river sampler inlet s were positioned as far away as possible from vegetation and eddy currents near the river banks , and ~15 cm off the river bed

. Isco sam pler inlet distance from the river banks ranged from 3.1

- 4.1 m during the high river discharge campaign, and 4.6

- 15.3 m during the low river discharge campaigns. Isco sampler inlet depths from the surface ranged from 46

- 71 cm during the high river dischar ge campaign, and 15

- 66 cm during the low river discharge campaigns. S ample bottles were retrieved every 2

- 4 days. Grab samples were also collected from the POTW and coal

- fired power plant (CFPP) in the study domain using acid

- cleaned polypropylene dipper s and poured into sample bottles

. Ultra

- clean handling methods for sample deployment and collection were employed to avoid contamination of the collected samples ( Landis et al., 2002 )

. All

c ollected samples were packed in ice and shipped overnight to the laboratory

.
Conductivity Onset (Cape Cod , MA) HOBO Model U24

- 01 in

- river sondes were deployed to measure temperature and electrical conductivity at each of the Isco sampling sites at 5 min intervals

. A YSI (Yellow Springs, OH) Model 556 multi

- parameter instrument was utilized to collect traceable temperature compensated specific conductivity (SC ) readings to scale each Onset in

river sonde using manufacturer provided HOBOware ® Conductivity Assistant software ( Appendix A.2 )

. The YSI in strument was calibr ated each morning using YSI

- 3161 1000 μS cm - 1 standard solution , checked again each night , and checked weekly using YSI

- 3165 100000 μS cm 1 standard solution

. Daily c alibration check precision (n=42) was 98 ± 2% (mean ± st andar ddev iation ) , and the weekly high range linearity check preci sion (n=9) was 95 ± 4% . A collocated Onset in

- river sonde was deployed at S0 3

- D ownstream1 and the collocated p recision (n=16685 ) was 98 ± 3%

. Specific c onductivity of Isco samples was determined in an EPA Class 100 clean room using a Mettler Toledo ( Colu mbus, OH ) Model S47

- K meter equipped with an InLab ® 731 probe. A two point calibration curve was generated each day using certified Mettler Toledo 1413 μS cm - 1 and 12.88 mS cm - 1 conductivity standards. Accuracy checks were conducted using a Ricca Chemical (Arlington, TX) 1 , 50, 100 , and 200 mS cm - 1 certified secondary standards to ensure linearity

. Replicate analysis was performed on a minimum of 10 % of samples and the observed precision (n= 5 4 ) was 99 ± 1 % , and collocated sample precision (n= 123 ) was 98 ± 5 %

. The mean of the two five

- min Onset in

- river conductivity data points corresponding to the two daily Isco sampling times were compared to the Isco sample conductivity and the relative precision was found to be 93 ± 1 0 % ( Appendix B.1 )

.
Major Ani ons An ions were quantified using a Dionex (Sunnyvale, CA) Model ICS

- 2000 i on chromatograph y instrument following an optimized U.S. EPA Method 300.1 ( US EPA, 1 997 ) technique as described below

. Each sample was injected twice to evaluate analytical precision. Anion separations were performed with a 200 μL sample loop injection onto a Dionex IonPac © AG18 (4x50mm guard) and AS18 (4x250mm analytical) cation

- exchan ge column, utilizing an isocratic potassium hydroxide eluent method. The analytical columns used me t performance criteria speci fied in U.S. EPA Method 300.0 (1993). The ICS

- 2000 instrument was externally cali brated using a six point curve generated from a mixed Dionex s even a nion s tandard ( # 05 7590) . Initial calibration verification was performed with secondary source standards (High Purity Standards, Charleston , SC) and NIST ( Gaithersburg , MD) Standard Reference Materials for Cl - ( # 3182) and Br - ( # 3184). Calibration stabilities were verified daily by mid

- level continuing calibration verification samples. Linear calibration curve statistics were verified with minimum acceptance criteria of a coefficient of determination ( r 2 ) > 0.999. In order to increas e the linear dynami c range, two analytes (sulfate (SO 4 2

- ) , Br - ) were pr ocessed with a quadratic regression , utilizing seven calibration points with minimum acceptance criteria of r 2 > 0.99. Prior to injection, allfield samples were filtered using Millipo re (Billerica, MA) IC

- Millex syringe filters (25mm, 0.45μm PTFE). Each chromatogram was visually verified for peak shape, retention and identification. CWTF samples were all diluted 1000x with ASTM Type I ultra

- pure water (18.2 M Ω
⋅ cm) prior to analysis

. Replicate analysis was performed on ~10% of all samples and the

re sulting ana lytical precision ranged from 99 ± 2 % ( Br - ) to 100 ± 1 % ( Cl - , SO 4 2

- )

. Collocated samples were collected and analyzed for ~3 0% of all observations and the resulting precision

ran ged from 96 ± 10 % ( SO 4 2

- ) to 99 ± 2 % ( Cl - )

. A summary of all a nalyte specific i nstrument d etection l imits , m ethod d etection l imits , and analytical/collocated precision are presented in Appendix A.3

.

USGS River G age Data River water discharge volumes for the sampling domain were obtained from the U

. S

. Geological Survey (USGS)

. Hourly discharge data is available from October 1, 2007 through 2014 (USGS, 2015) for g age station #03025500 (Franklin, PA) located 1.5 km upstream of site S0 1

- Upstream on the Alleg heny River , and g age station #03031500 (Parker, PA) located 11 km downstream of S05

- PDW1

. T he Parker g age station is located 1.8 km downstream of the Clarion River confluence . The water discharge contribution from the Clarion River as measured by gage #0 3030500 (Piney, PA) was subtracted from the gage value downstream of S05

- PDW1 to estimate river discharge closure within the u pper Allegheny River sampling domain ( Appendix B.2 )

. Categorization of CWTF Discharge Impacted Samples The non

- continuous operati on schedule of the CWTF resulted in periods with and without discharge

. High time resolution (5 min) in

- river sonde conductivity data from each of the sampling sites clearly elucidated defined CWTF conductivity discharge plume tracer events as they were t ransported and hydrologically dispersed downstream through the upper Allegheny River sampling domain. Transit time analysis was performed independently between the CWTF

- P45 (45 m downstream of the discharge pipe) and each downstream site , similar to condu cting a dye or tracer study in the river (Smart and Laidlaw, 19 7 7 ; Kunkel and Radke, 2011 )

. An e xample site

- to

- site transit time analysi s of the CWTF discharge conductivity plume s to the 12.2 km downstream site S03

- Downstream1 from September 24

- 29, 2012 i s presented inFigure 2

. The example transit times ( ∆ t) defined as the CWTF median discharge time to the maximum downstream conductivity value were ~16 hours during this period, and are depicted as dropdown lines in Figure 2. Figure 3 depicts the CWTF

- P4 5 and S03

- Downstream1 site conductivity data example after the ∆ t = 16 hour plume transit time adjustment , showing the conductivity peaks observed at site S03

- Downstream1 align with the CWTF discharge times ( drop down lines represent the programmed Isco sa mpling times )

. Transit times were calculated independently for each sampling site during each seasonal sampling period.

Based on these empirically derived plume transit times to each of the downstream sites and the duration of the CWTF discharge, all Isc o samples were categorized as “discharge impacted” if one or both of the sample collection times (9:00 and 12:00 EST) fell within the conductivity plume impact time for each site

. Based on the transit time analysis Isco samples from the example time perio d : September 24

- 28 and September 29 were categorized as “impacted” and “non

- impacted”, respectively. Each Isco sample and its associated time corrected in

- river sonde conductivity data was visually evaluated to ensure accurate categorization

. S06

- PDW2 s ite was too far down stream to track the CWTF discharge conductivity plumes and was therefore not included in the in tra

- site analysis

. Disinfection Byproduct Empirical Modeling Empirical modeling of DBP formation in PDW was conducted to estimate the impac t of additional Br - contributed by CWTF discharges on total THM and brominated analogs at two downstream intakes. The EPA empirical models employed ( U.S. EPA , 1998; Solarik et al., 2000 ) are statistically

- based and were developed by EPA for predicting DBP formation during water treatment disinfection using chlorine and ozone. Each model was formulated through multiple step

- wise regression analysis and takes the form of a multiple regression equation. While the predictive empirical models may not accurate ly predict the complex conditions at any particular PDW (Brown et al., 2011) they are considered to generally descriptive and useful for the evaluation of water treatment facilities and human risk assessment ( Sadiq and Rodriguez, 2004; Chowdhury et al., 20 09)

. Different versions of the model were evaluated based on their ability to predict the reported THM concentrations at PDW1 and PDW2 during our sampling periods

. Model input parameters are presented in Appendix Table A.4. Due to the use ofprechlorina tion, the raw water version of the THM prediction model provided the best predictive results for both PDW1 and PDW2, and was utilized for all subsequent analysis. Based on median raw water Br - , temperature, and pH measurements made during this study and P ADEP organic carbon measurements available for 2012

- Quarter 2 (Q2) and 2012

- Q3 at a location ~28 km upstream of PDW1 (PADEP, 2014 ; ), the model predicted 2012

- Q2 (high river discharge regime) total THM to be 50 ppb versus an actual reported concentration o f 68, and the model predicted 2012

- Q3 (low river discharge regime) THM to be 107 ppb versus an actual reported concentration of 110 ppb.
EPA’s empirical raw water DBP model was also run for PDW2 using the median raw water Br - , temperature, and pH measurem ents made during this study and PADEP organic carbon measurements available for 2012

- Q2 and 2012

- Q3 at a location ~ 25 km u pstream (PA DEP, 2014). The model predicted 2012

- Q2 (high river discharge regime) THM to be 47 ppb versus an actual reported THM con centration of 53, and the model predicted 2012

- Q3 (low river discharge regime) THM to be 99 ppb versus an actual reported THM concentration of 101 ppb. Based on the reasonable results of the raw water model, it was used to estimate the impact of the Br c oncentrations attributed to CWTF discharges on PDW THM concentrations.
Statistical Analysis Data processing and all statistical analy ses were performed using SAS v.9 .4 (SAS Institute, Cary, NC). Parametric statistics used in this analysis include: a t

- te st for independent samples, and one - way analysis of variance (ANOVA). The assumptions of the parametric procedures were examined using residual plots, skewness and kurtosis coefficients, Shapiro

- Wilk test , and the Brown

- Forsythe test. If assumptions of t he parametric procedures were violated , the n the Wilcoxon and Kruskal

- Wallis non

- parametric procedures were used, respectively

. Analytic al and collocated precision w ere calculated as 1

- ( absolute percent difference ) for replicate and collocated sample anal ysis, respectively

. In order to determine which combination of major anions best predict s conductivity , the results, which were first obtained using stepwise regression glmselect procedure, were verified using the general linear model sums of squares and Spearman correlation matrix. One

- sided tests and a level of significance of α =0.05 was used for all statistical procedures unless otherwise stated

.To determine if the CWTF discharge significantly increased halide concentrations at downstream sampling si tes, the downstream Isco samples were evaluated by both intra

- and paired inter

- site statistical hypothesis tests

. The downstream inter

- site “discharge impacted” Isco samples were paired with their associated transit time corrected S01

- Upstream sample. D uring the spring high river discharge measurement intensive , S03

- Downstream1 Isco samples paired with S01

- Upstream Isco samples on the same day while S01

- Upstream Isco samples paired with S04

- Downstream2 and S05

- PDW1 Isco samples on the following day. Dur ing low river discharge measurement intensives in the summer and fall, S03

- Downstream1 Isco samples were lagged by one day whereas S04

- Downstream2 and S05

- PDW1 Isco samples were lagged by two days with their paired S01

- Upstream sample

.
Upper Allegheny Mas s Balance Model A box model detailing daily river baseline and source discharge loading was developed to investigate the dilutive capacity of th e river in our study domain and to evaluate the estimated CWTF impact on Br - and Cl - a t downstream S05

- PDW1 base d on the inter

- and intra

- site comparison method. Daily river baseline loadings were calculated as the product of the river volumetric flow and the S0 1

- U pstream river concentration. Source discharge contributions from S02

- CWTF were calculated as the prod uct of the facility reported daily discharge volumes and the daily EPA sample concentrations. Source loading from the POTW and CFPP (without flue gas desulfurization ( FGD ) scrubbers) in the study domain (Figure 1) were calculated using the mean EPA discha rge grab sample concentrations and facility reported monthly discharge volume (adjusted to daily discharge volume). The water volume c losure of the box model in the u pper Allegheny River study domain was evaluated using the results calculated using Equati on 1 (Appendix B.2)

.

CCCCCCCCCCCCCC ( % ) = 100

− � � PPPPPPPPPPPP GG GG − ( FF FF FFFFFF GG GG + CC CC RR RR GG GG ) PPPPPPPPPPPP GG GG � ∗ 100 � (1)

Results and Discussion Monitoring Campaign Allegheny River Condition sThe river flow condition s and CWTF wastewater discharge characteristics during the sampling campaigns were evaluated to see if they w ere generally representative of overall 2012 conditions. A n on - para metric Wilcoxon Two

- Sample Test , found no significant difference between the 20 12 daily mean Allegheny River high discharge period volumes (25,246 ± 12,067 m 3 min - 1 ; p=0.56) and the discharge volumes during the study campaign sampling period (25,477 ± 3,880 m 3 min - 1 ; Appendix B.3a ) . However, the Wilcoxon two

- Sample Test did find a significant difference between the 2012 daily mean Allegheny River low discharge period volumes (5,059 ± 1082 m 3 min - 1 ; p=0.05) and the discharge volumes during the study campaign sampling period (4,591 ± 566 m 3 min - 1 ; Appendix B.3b ). When evaluating the 2012 Allegheny River discharge volumes to the available dai ly historical records (2007

- 2014 ), we found the 2012 high river discharge period volumes to be consistent with the average values ( 25,266 ± 11 , 575 m 3 min - 1 ; p=0.56 ; Appendix B.3a ) but the low disch arge rates were found to be significantly lower than the historical average ( 4,977 ± 1,025 m 3 min - 1 ; p<0.001 ; Appendix B.3b ) due to a summer drought.
The median CWTF treated wastewater discharge volumes from April 2

- October 31, 2012 (n=157) was 333,976 liters per operation day with a range of 8,210

- 750,269 liters. The median CWTF discharge volume during the monitoring campaigns was (n=38) 245,696 liters per operation day with a range of 9,017

- 676,075 which was not significantly different from the

ov erall period (Wilcoxon Two

- Sample Test p=0.06). The facility indicated its discharge volumes were a function of customer demand for brine treatment services and facility operational conditions.

Upper Allegheny River Observations The overall stud y conduct ivity and halide results are generally consistent with previous observations ( States et al., 2013 ) , which demonstrate that background levels in the u pper Allegheny River are relatively low and significantly increase downstream. When the high and low river discharge regimes are examined independently ( Table 1 ) , the assimilative dilution capacity of the river during periods of high discharge is evident for halide species and results in significantly (p<0.001) lower conductivity, Br - , and Cl - at each of the s ites. The median domain baseline conductivity (126 μ S cm - 1 ), Br - (25 ppb), and Cl - (13.1 ppm) at S01

- U pstream duringthe spring high river discharge campaign were lower than the corresponding medians of 174 μ S

cm - 1 , 72 ppb and 21.0 ppm during the combined summer/fall low river discharge c ampaigns

. The med ian S05

- PDW1 conductivity (158 μ S cm - 1 ), Br - (38 ppb) and Cl - (17.0 ppm) during the high river discharge c ampaign increased to 202 μ S cm - 1 , 85 ppb and 23.5 ppm, r espectively, during the low river discharge campaigns. While the overall halide concentration s were lower durin g the high discharge spring campaign , the S05

- PDW 1 site downstream of the CWTF discharge in our study domain wa s significantly higher than S 01

- U pstream baseline site for conductivity , Br - , and Cl -

.

Lower Allegheny River Observations Whil e not in the upper Allegheny River study domain, comparing the results observed at S06

- PDW2 ~100 km further downstream from S01

- PDW1 is informative to evaluate the integrative impact of additional downstream sources in the watershed on another public drink ing water

resource ( U.S. EPA, 2015; Appendix B.4a

- c ). Significant increases in conductivity, Br - , Cl - , and SO 4 2

- were observed between S05

- PDW1 and S06

- PDW2 during the low river discharge campaigns, and signific ant increases in conductivity , and SO 4 2

- wer e observed during the high river discharge campaign ( Table 1 ; Appendix B.4a

- d ). On an integrated basis during the high river discharge campaign, there was a 1 5 4% increase in SO 4 2

- (11.3 to 28.7 ppm), a 1 6% increase in conductivity (157 to 182 μ s cm - 1 ), a 3% decrease in Br ( 36 to 3 5 pp b ), a nd an 8% decrease in Cl - ( 17.3 to 15.9 ppm ) from S05

- PDW1 to S06

- PDW2

. D uring the low discharge campaigns there were significant increases ( Table 1 ; Appendix B.4a

- d ) in all contaminant concentrations at S06

- P DW2 r elative to S05

- PDW1 including a 7 54 % increase in SO 4 2

- (9.6 to 82.0 ppm), a 8 3% increase in conductivity (204 to 374 μ s cm - 1 ), a 63 % increase in Br - (87 to 142 ppb), and a 29 % increase in Cl - (23.6 to 30.4 ppm). A step

- wise multi

- linear regression an alysis found that conductivity at S01

- Upstream and S06

- PDW2 were best predicted by Cl - and SO 4 2

- (R 2 = 0.965), while conductivity at S03

- Downstream1, S04

- Downstream2, and S05

- PDW1 were best predicted by Cl - and Br - (R 2 = 0.862 ). This finding indicates tha t in the u pper reaches of the Allegheny River (S03

- Downstream1 to S05

- PDW1) downstream of the CWTF discharge conductivity is halide dominated, whereas in the lower reaches of the Allegheny River (S06

- PWD2) it reverts back to a more SO 4 2

- dominated system.The distance, tributary inflow ( Appendix B.2 ), and additional anthropogenic discharge sources downstream of S05

- PDW1 preclude identification of the source types contributing to the elevated concentrations at S06

- PDW 2 within the context of this work. One indication that coal

related sources are substantially impacting halide concentrations at S06

- PDW2 is the large increase in SO 4 2

- (Table 1) in combination with a downward shift i n the Cl - /Br - ratio in relation to the u pper Allegheny River study domain ( Appe ndix B.5 ). D uring the low river discharge campaigns the median Cl - /Br - dr ops from 278 (S05

- PDW1) in the u pper Allegheny River study domain to 217 (S06

- PDW2) suggesting an impact from a characteristically lower Cl - /Br - source such as u pper Pennsylvanian Co nemaugh and Monongahela formation bituminous coals that are mined regionally ( Seere and Lee, 2009 ; U.S. EPA , 2015 ).

Impact of C WTF on S05

- PDW 1 Raw Water The operation s chedule of the CWTF during the study campaigns , nominally 06:00

- 13:00 EST Monday throug h Friday, allowed us to investigate downstream river conditions both in the presence and absence of treated oil and gas wastewater discharge. During both the high and low river discharge campaign s , the automated samplers captured a sufficient number of CW TF discharge impacted and non

- impacted categorized samples at the S03

- Downstream1 , S04

- Downstream2 river sites , and S05

- PDW 1 intake for inter

- and intra

- site statistical analyse s . A summary of the high and low river discharge regime s CWTF impacted and non

- impacted categorized data and inter

- site paired Kruskal

- Wallis one - sided test results are presented in Tables 2 and 3, respectively

.

Evaluating the impact of the S02

- CWTF discharge on downstream sites can be characterized on

an inter

- site basis by evalua ting the S01

- U pstream conductivity and anion species means versus the downstream site means for those species that were found to have no significant sources in the study domain other than the CWTF discharge. In this case we define no other significant sou rce impacting the PDW intake as a condition whereby (i) the non

- discharge impacted categorize d samples at S0 5

- PDW1 and their paired S01

- Upstream site samples are not significantly different during both high (Table 2 ) and low (Table 3 ) river discharge condi tions and (ii) no significantcontribution from the POTW and CFPP discharge grab s amples , only Br - meets this criterion. During both the high (Table 2) and low (Table 3) river discharge sampling periods the observed Br - concen trations at S03

- Downstream1, S04

- Downstream2, and S05

- PDW1 raw drinking water intake were not significantly different than the paired S01

- U pstream Br - concentrations during

non - discharge impacted days, but were significantly higher during CWTF discharge impacted days . These relations hips for the Allegheny River low discharge regime are clearly depicted in Figure 4 a where the stable Br - concentrations throughout the study domain during non

- CWTF discharge days are contrasted with the clearly observable downstream enhancement during disc harge days, which was initially high est at the S03

- Downstream1 site with decreasing concentrations as a result of dilution and hydraulic dispersion down stream to S05

- PDW1. This inter

- site analysis takes into account the periods of CWTF discharge only and provides a quantitative overall estimate of Br - enhancement through the study domain. The magnitude of the integrated Br - enhancement during low river discharge from the CWTF on downstream sites was 109% (81 ppb) at S03

- D o wnstream1, 45% (33 ppb) at S04

- D o wnstream2, and 5 1% (38 ppb) at S05

- PDW1. During high river discharge the integrated Br - enhanc ement on downstream sites was 50% (14 ppb) at S03

- D ownstream1, 31% (8 ppb) at S04

- D ownstream2, and 50% (13 ppb) at S05

- PDW1. At first glance the lower relative impact of the CWTF effluent discharge on observed Br - concentrations at the S03

- Downstream1 site during the high river discharge period seemed to suggest that the Allegheny River’s assimilative capacity was adequate to dilute CWTF related contaminants down to lower relative levels within the 12 km distance between the discharge and the site

. However, when we evaluated the Isco sampling times categorized as CWTF impacted versus the associated in river sonde conductivity plume impact time ( e.g., Appendix B. 5 ), it was o bserved that the automated sampler did not capture the main discharge plume which was still clearly evident and not fully mixed

. The systematic mismatch of Isco sampling and CWTF discharge plume impact times encountered at site S03

- Downstream1 during the high discharge sampling campaign biased the relative impact down in relation to both the impact observed at the site during the low river discharge campaigns and the S04

- Downstream2 and S05

- PDW1 sites during the high river discharge campaign

. W hile Cl - presented a similar overall response as Br - (Figure 4 b ) demonstrating a clear impact from CWTF effl uent, the S05

- PDW1 site high river discharge sampling period Cl - concentration was significantly higher (p=0.016) than S01

- Upsteam during non

- discha rge days (Table 2) ; suggesting anothercontributing source(s) (e.g., CFPP discharge) and precluding its inclusion in the inter

- site analysis.

T he impact of CWTF effluent discharge on downstream sites within the study domain was also evaluated using CWTF d ischarge categorized int r a - sit e analysis , whereby the CWTF impacted and non - impacted sample subsets at each site were statistically compared (Table 4; Figures 4a

- c)

. Both downstream river sites (S03

- Downstream1 , S04

- Downstream2 ) and S05

- PDW 1 were found to have significantly higher conductivity , Br - , and Cl - during both high and low river discharge conditions when being impacted by the CWTF effluent discharge plume

. The discharge categorized data from the high and low discharge regime campaigns used for in tra

- site analysis

are presented in Table 4 and are depicted in Figure s 4a

- c
. The S01

- Upstream conductivity data 174 ± 13 μS cm - 1 has a relatively tight range compared to the CWTF downstream sites and the distribution is not significantly different than normal (Shapiro

- Wilk; p=0.166 ; Figure 4c ). The magnitude of the mean conductivity impact from the CWTF on downstream sites during low river discharge, determined by evaluating all the impacted versus non

- impacted categorized samples, was an increase of 15% (28 μ S cm - 1 ) at S03

- D ownstream1, 12% (23 μ S cm - 1 ) at S04

- D ownstream2, and 12% (23 μ S cm - 1 ) at S05

- PDW 1 . The CWTF discharg e categorized Cl - data from the low discharge regime campaigns are depicted in Figure 4b . Using the same analytical approach described above, the magnitude of the Cl - impact from the CWTF discharge on downstream sites was an in crease of 40% (8.4 ppm) at S 03

- D ow nstream1, 21% (4.5 ppm) at S04

- D ownstream2, and 19% (4.3 ppm) at S05

- PDW1. The CWTF discharge categorized Br data from the low discharge regime campaigns are depicted in Figure 4a. The magnitude of the Br - impact during the low discharge regime wa s an increase of 105 % (7 9 ppb) at S03

- D o wnstream1, 55% (39 ppb) at S04

- D ownstream2, and 53% (39 ppb) at S05

- PDW1. In contrast, the S01

- U pstream baseline and non

- impacted downstream Br - mean concentrations were indistinguishable (74 ± 2 ppb) , which is a st rong indication that non - impacted samples were properly categorized and that there were no other significant sources of Br - in the study domain (Figure 4a)

.During the high river discharge sampling regime the overall observed concentra tions and the magnit ude of CWTF impact were lower at all downstream sites due to the river’s increased dilution capacity. The CWTF effluent discharge enhancement for (i) conductivity was an increase of 7% (9 μ S cm - 1 ) at S03

- D ownstream1, 6% (8 μ S cm - 1 ) at S04

- D ownstream2, and 2% (3 μ S cm - 1 ) at S05

- PDW 1 , (ii) Cl - was an in crease of 20% (2.7 ppm) at S03

- D ownstream1, 11% (1.5 ppm) at S04

- D ownstream2, and 5% (0.9 ppm) at S05

- PDW1, and (iii) Br - was an increase of 75 % (18 ppb) at S03

- Downstream1, 31% (8 ppb) at S04

- D ownstream2, and 22% (7 ppb) at S05

- PDW1.

Cl - /Br - Ratio Halide ratios (e.g., Cl - /Br - ) are used in hydrogeological studies to elucidate water migration because the species primarily occur as dissolved monovalent ions that typically are conserved during movement through en vironmental compartments ( Davi s et al., 1998; Freeman 2007; Alcala and Custodio, 2008 ). Formation water from Devonian oil

- and gas

- bearing units such as the Marcellus are enriched in Br - resulting in characteristically lower Cl - /Br - ratios ( Ferrar et al., 2013; Warner et al., 2013). The Cl - /Br - ratio of the S02

- CWTF discharge was significantly different (Kruskal

- Wallis p<0.0001) during the high (n=13; 110.6 ± 6.2 ) and low (n=23; 90.4 ± 2.4 ) discharge regime sampling campaigns. The Cl - /Br - ratio of data p resented by Warner et al., ( 2013; and references within) was 127.2 from a similar CWTF discharge in Western Pennsylvania treating a combination of Marcellus and conventional Devonian produced wastewater (2010

- 2 012), 107.8 from raw u pper Devonian produced w ater, 93.4 from raw Marcellus produced water, and 108.5 from raw Lower Devonian produced water. The discharge categorized Cl - /Br - ratio data from the low discharge regime campaigns indicate higher values were observed during non

- impact conditions compared to impacted conditions ( Figure 5 )

. Similar to the Br - results, good agreement between the low discharge regime S01

- U pstream (316

. 0 ± 8 0. 3 ) and non - impact categorized downstream Cl - /Br - ratios is an indication of no additional significant sources of Br - e nriched discharge into the study domain. A significant reduction (p=0.023) of the Cl - /Br - ratio is observed at the S03

- D ownstream1 site when being impacted by the CWTF discharge ( 205.9 ± 38.9 ) and then increases as the halides are diluted by the more Cl - dominated baselin e river flow ( 316

. 0 ± 8 0. 3 ) down to sites S04

- D ownstream2(246.2 ± 33.6) an d S05

- PDW1 ( 243.7 ± 35.5; Figure 5) . Within the upper Allegheny study domain (S01

- Upstream to S05

- PDW1 ) elevated total Br - and low Cl - /Br - sample ratios appear to be a good indicator of CWTF discharge downstream impact.

In the context of S06

- P D W 2 and other locations in the lower reaches of Allegheny River watershed, interpretation of Cl - /Br - ratios becomes more difficult as the number of sources discharging into th e river and its tributaries dramatically increase (e.g., public/commercial wastewater treatment facilities, discharges from coal mines, coal bed methane (CBM), CFPP). The mean Cl - /Br - ratio observed at S06

- PDW2 during the high river discharge regime (460 ± 71) was significantly higher (p<0.0001) than the Cl - /Br - ratio during the low river discharge regime (216 ± 17), suggesting that the elevated halides measured during the low river discharge campaign were the result of discharges of wastewaters containing characteristically lower Cl - /Br ratios into the river. Coal mined in the region from the u pper Pennsylvanian Conemaugh and Monongahela formation bituminous coals (e.g., Pittsburgh #8; Kosanke, 1984 ) have been found to contain high concentrations of Br - (13.4 ppm) and a low Cl - /Br - ratio of 72.6 (Seere and Lee, 2009)

. In addition, contemporaneously collected samples of wastewater discharges from other anthropogenic activities exploiting the same coal formations and discharging into the Allegheny River or its tributaries between sites S05

- PDW1 and S06

- PDW2 also contain Cl - /Br - ratios substantially lower that the upper Allegheny baseline S01

- Upstream values (316

. 0 ± 8 0. 3 ) including : coal ash (40.7) , treated FGD ( 68.4 ) , CBM (129.9) , treated AMD ( 158.1 ) , AMD seeps ( 172.6 ) , and active coal mine runoff (183.0 ; EPA 2015)

.

The timeline of increasing PDW THM concentrations along the Allegheny River and its perceived correlation to expanding exploitation of the Marcellus shale in western Pennsylvania for gas and o il produ ction reported by States et al. ( 2013 ), was also concurrent with the regional trend of installing air pollution control syste ms in CFPP s. The development of the EPA 2005 Clean Air Interstate Rule, the 2011 Cross

- State Air Pollution Rule, and the 2 011 Mercury and Air Toxics Standards have led to the wide spread retrofitting of the US CFPP fleet with FGD scrubbers. Sc rubber installations reached 64% of CFPPs by the end of 2012 ( US E nergy I nformation A dministration ) . Among other pollutants such as S O 2 and divalent mercury species(e.g., HgCl 2 , HgBr 2 ), scrubbers also efficiently remove halides from the stack gas that originates naturally in the combusted coal. Once FGD scrubbers remove components from the stack exhaust (e.g., halides and sulfur dioxi de), CFPPs typically discharge treated scrubber wastewater as well as storm water runoff from coal and residual ash piles enriched in halides and sulfate to surface waters in western Pennsylvania ( U.S. EPA 2015 ).

Upper Allegheny Mass Balance Model The wat er volume closure of the box model in the upper Allegheny study domain was evaluated using the results calculated using Equation 1, and the daily mean volume closure was found to be 88 ± 11%. The model on average underestimated the volume of water in the system because of inflows from three ungaged tributaries (Turkey Run, Sandy Creek, Scrubgrass Creek) into the Allegheny River between sites S01

- Upstream and S05

- PDW1 ( Appendix B. 2 ) were not included in the model . Water volume closure during the high river discharge regime (95 ± 12) was on average better than during the low r iver discharge regime (84 ± 8). During the low discharge campaigns , the river baseline flow contributed an average of 448 kg of Br - and 133 , 97 0 kg of Cl - into the model dom ain on CWTF d ischarge day s . The daily mean

source co ntribution from S02

- CWTF was 202 k g Br - and 18,208 k g Cl - , t he contribution from the POTW was 0.0 k g Br - and 1,332 Cl - , and the contribution from the CFPP was 0.1 k g Br - ; and 196 k g Cl - . Assuming homogeneous steady state conditions with no additional source terms, the box model predicts the S02

- CWTF discharge would contribute an aver age of 44 ± 22 % of the Br and 14 ± 7 % of t he Cl - into the upper Allegheny R iver sampling domain (Figure 6a ). The box model results ag ree well with the 53 % Br - ( 39 ppb ) and 19 % Cl - ( 4.3 ppm ) contributions from the intra

- site analysis , and the 51% Br - ( 38 ppb ) and 26% Cl - ( 5.4 ppm ) contributions from the inter

- site analysis at S05

- PDW1 (Table 5) . The daily box model average estimated tot al Br mass (649 k g day - 1 ) contribution into the u pper All egheny River domain was within 8 % of the S05

- PDW1 measurement based Br - mass estimate (703 kg day - 1 ), indicating the observed impact at PDW1 during low river discharge could be explained through the contributions of the three known discharge sources into the river within the uncertainty of the water volume closure

. During the high river discharge measurement campaign, the Allegheny River water volume was five times greater than during the low river d ischarge measurement campaigns. While the highdischarge campaign halide concentrations were lower, the river baseline discharge contributed more tha n double the halide mass (mean of 97 3 k g of Br - and 490 , 853 k g of Cl - ) into the model dom ain per CWTF disc harge day than was observed during the low river di scharge periods. The daily me an source con tributions from S02

- CWTF was 159 k g Br - and 17 , 323 k g Cl - (Figure 6b)

. The daily mean source contributions from the POTW and CFPP were 0.0 and 0.1 kg Br - ; and 1, 534 and 147 kg Cl - , respectively. During the high discharge regime the box model predicts the S02

- CWTF d ischarge would contribute 16 ± 6 % of the Br - and 4 ± 1 % of the Cl - into the river domain. While t he box model results agree relatively well with the 2 2 % Br - ( 7 ppb ) and 5 % Cl - ( 0.9 ppm ) contributions from th e intra

- site analysis (Table 5), o verall it under predicts the total average daily loading in the river versus the S05

- PDW1 me asurement based estimate s (Figure 6b). The generally higher CWTF impact estimated by the inter

- and intra

- site analyses was expected as the Isco sampling times were coincident with the CWTF effluent conductivity impacts measured at S05

- PDW1 by the in

- river sonde , whereas the box model assumes a homogeneous well mixed system

. The observed CWTF effl uent discharge impacts at S05

- P D W 1 suggests the impacts of the elevated halide concentrations on the raw water plant intake could be partially mitigated by conditional pumping based on near

- field upstream conductivity measurements

.

I

mplications of CWTF Discharges on PDW THM Concentrations As reported by States et al. ( 2013 ) the PWSA and other w ater utility operators relying on the Allegheny as their raw water source observed significantly increased total THM concentrations and substan tially higher than normal relative abundances in brominated analogs in 2010 , and hypothesized that these observations were a r esult of increased Br - concentrations in their river source water

. A time series analysis of Allegheny R iver Br - concentration wa s not possible then

as routine Br - measurement s by PADEP were not initiated until late 2009 ( USEPA, 2014 ). A current time series of quarterly THM concentrations in finished drinking water and the annual rolling average s a re presented in Figure 7 a for site S05

- PDW1 using all available data contained in the PADEP Drinking Water Reporting System ( PADEP, 2014 )

. A n upward trend in the annual rolling average of THMs in finished drinking water , and an underlying seasonal variation

are observed. A linear regress ion analysis was completed for quarterly TH M rolling concentratio ns from 2010

- Q1 through 2014

- Q4 (Figure 7 b) and a significant (p<0.0001;r 2 =0.8 6 4 ) increasing trend of ~ 6 ppb per year was found. At this rate , S05

- PDW1 will exceed the EPA THM standard of 8 0 ppb by 2016. The Q3 THM concentrations for 2010 through 2014 are significantly higher than the other quarters (p =0. 01 1 ) reported during this period . The likely contributing factors to elevated Q3 THM concentration s are significantly higher Br - ( p= 0.015 ) and organic carbon ( p<0.0001 ) concentrations during the low river discharge regimes, as well as the higher water tempera tures in the summer ( Appendix A. 2 ). EPA’s empirical raw water DBP treatment model was used to estimate the impact of the CWTF discharg e on S05

- PDW1 THM formation by comparing discharge impacted and non

- discharge impacted intra

- site analysis scenarios during the low (2012

- Q3) discharge regime when the highest THM conce n trations are reported (Figure 7 a)

. The m ean low river discharge non - i mpact categorized Br - concentration from S05

- PDW1 (7 3 ppb; Table 4 ) and CWTF impacted categorized (112 ppb; Table 4 ) samples were used to parameterize successive model runs . The predicted total THM concentration for the non - impacted baseline river conditi on was 105 ppb , and t he predicted CWTF discharge impacted river condition yielded an estimated total THM value of 109 ppb (3% increase). While the additional Br - in the S05

- PDW1 raw water intake attributed to the CWTF enhancement discharge was not estimat ed to substantially contri bute to the overall total THM , the model predicted an overall decrease in chlorinated THM analogs and

a large 41% increase in the more toxic brominated THM analogs. The model estimated a 37% increase in bromodichloromethane (19.0 to 26.0 μ g L - 1 ), a 113% increase in bromoform (0.2 to 0.4 μ g L - 1 ), and a 117% increase in dibromochloromethane (4.0 to 8.7 μ g L - 1 ).

Since S06

- PDW2 samples could not be categorized as impacted and non

- impacted by S02

- CWTF due to the dissipation of the conductivity plume and additional downstream sources , the relative impact of aggregate CWTF discharges were based on the receptor modeling results from measurements made during this same study period at S06

- PDW2 ( U.S. EPA 2015)

. During the low river d isch arge regime, U.S. EPA (2015 ) attributed 37% and 59% of Br - at S06

- PDW2 to CWTF discharges and coal

- fired power plants equipped with flue gas desulfurization scrubbers, respectively

. EPA’s empirical raw water DBP treatment model was used to estimate the im pact of the total aggregate of CWTF discharge s on S06

- PDW2 THM formation by comparing mean observed Br - concentration to the mean Br - concentrations minus the estimated aggregate CWTFcontributions during the low (2012

- Q3) discharge regime. The mean low r iver discharge Br concentration from S06

- PDW2 (142 ppb; Table 1 ) and the Br - concentration with the estimated 37% CWTF contribution removed (89 ppb ) were used to parameterize successive model runs. A predicted total THM contribution at S06

- PDW2 from CWTF attributed Br - was 3 ppb , with a 47 % increase in brominated THM analogs. The model estimated a 41% increase in bromodichloromethane (18.2 to 25.7 μ g L - 1 ) , a 128% increase in bromoform (0.3 to 0.7 μ g L - 1 ) , and a 133% increase in dibromochloromethane (5.0 t o 11.5 μ g L - 1 )

.

The empirical THM modeling results corroborate the States et al. (2013) conclusion that increased Br - concentrations in the Allegheny River attributable to CWTF wastewater discharges water can substantially shift PDW total THM from chlorin ated to more toxic brominated analogs

. However, the empirical THM modeling does not support the contention that Br attributed to CWTF discharges affects t he overall trend of increasing THM concentrations (Figure 7 b ). F rom 2010 to 2014, PADEP data shows a significantly (p=0.0045) decreasing Br trend in the upper reaches of the Allegheny River in the vicinity of S05

- PDW1 (Figure 7c) during the concurrent increasing trend in total THM (Figure 7b)

. The significantly decreasing Br - trend (p=0.005; Appendix B.7) is also observed in the lower reaches of the Allegheny River in the vicinity of S06

- PDW2 during the concurrent (p=0.003) increasing trend in total THM from 2010 to 2013 (Appendix B.6). A sensitivity analysis of the THM formation model parameterized f

or both S05

- PDW1 and S06

- PDW2 suggests the increasing trend is more likely due to variability in the Allegheny River dissolved organic carbon (DOC) concentrations. Unfortunately, the available Allegheny River data includes primarily total organic carbon ( T OC ) rather than DOC concentrations which are more relevant to THM formation (U.S. EPA, 1998; Solarik et al., 2000) . There are no significant trends observed in the TOC data in either the upper ( p= 0. 18; Figure 7c ) or lower (p=0.15 ; Appendix B.7 ) Allegheny River

.

Conclusions As a result of Marcellus formation wastewater being diverted to other reuse and disposal options (PADEP, 2014), there has been a drastic reduction in the volume of oil and gas wastewater being discharged into the u pper Allegheny River and a corresponding decreasing trend inobserved Br - surface water concentrations 2009

- 2014 (Figure 7c ; Figure Appendix B.7 ) . But despite the declining Allegheny River Br - concentration , a significant impact of ongoing CWTFs operations to observed Br - co ncentrations during the high (2012 Q2) and low (2012 Q3) river discharge sampling campaigns were observed at downstream PDW intakes in both the upper and lower reaches of the river

. On days with active CWTF effluent discharge the magnitude of Br enhancem ent at S05

- PDW1 increased by an average of 39 ppb (53%) and 7 ppb (22%) for high and low river discharge campaigns, respectively

. The CWTF attributed Br - resulted in small modeled increase in total THM (3%), but a substantial positive shift from chlorinat ed to more toxic brominated THM analogs at both S05

- PDW1 (41%) and S06

- PDW2 (47%).
Suggestions for Future Monitoring While various sources of surface water and PDW analytical results are available in the public domain ( EPA STORET, PADEP DWPS ) , the fragmen ted nature both spatially and temporally between open river and PDW sample collection as well as the lack of DOC data prevent a process level understanding behind the underlying mechanisms for THM formation and the causality of observed trends. Integratin g and coord inating the PDW and surface water Fi monitoring programs ( e.g., sa mpling locations, time, analytes , parameters ) would provide a basis for evaluating/modeling THM production mechanisms and underlying system dynamics.

Acknowledgements : The EPA th rough its Office of Research and Development funded and conducted this research. The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of EPA. It has been subjected to Agency review and approved f or publication. Mention of trade names or commercial products do not constitute an endorsement or recommendat ion for use

. We thank Ram Vedantham, Sania Tong

- Argao, and Clay Nelson (EPA ORD) for their assista nce with data Quality Assurance; Todd Krantz an d Chris Impellitteri (EPA ORD), Angela McFadden , Louis Reynolds, Kelly Kroc k (EPA Region 3) , Sam Garvey and Mike Wheeler (Alion) for their logistical assistance ; and the CWTF and PDW operators for vo luntary access to their facilities

.List of Figures 1 Fi gure 1

. Plot of Allegheny River s ampling d omain d epicting the l ocations of s ampling s ite s and 2 m ajor s ource d ischarges

. River distances downstream from S02

- CWTF d ischarge are 3 noted in parentheses. 4 Figure 2

. Plot d epicting concurren t Onset in

- r iver s onde h igh r esolution (5 min) s pecific 5 conductivity observations demonstrating CWTF d ischarge plume t ransit time from s ite 6 S02

- CWTF (sonde located 45 m downstream from discharge pipe; CWTF

- P45) to s ite 7 S03

- Downstream1 (b lack t race)

. Drop lines denote the me dian discharge time (S02

- 8 CWTF ) and conductivity peak from each plume impact event (S03

- Downstream1 ), 9 respectively. The difference between the drop lines represents the plume transit time. 10 Figure 3. Plot d epicting t ransit time corrected Onset in

- river s onde h igh r esolution (5 min) 11 s pecific c onductivity o bservations at S03

- Downstream1 during l ow d ischarge regime 12 d emonstrating how Isco samples were categorized as CWTF “discharge impacted” 13 (Monday

- Friday) and “non

- impacted” (Saturday). Drop down lines denote Isco 14 sam pling times. 15 Figure 4

. Comparison of Allegheny River l ow d ischarge r egime S01

- Upstream site paired 16 sample baseline subtracted (a) bromide , (b) c hloride, (c) specific conductivity, and (d) 17 sulfate by s ite location and CWTF d ischarge i mpacted versus n on - i mpa cted time 18 period s. Dashed line indicates relative river “baseline” value

. 19 Figure 5. Comparison of Allegheny Riv er low discharge regime Cl - / Br - ratio by site location and 20 CWTF discharge impacted versus non - impacted time periods. Dashed line indicates 21 med ian “baseline” value at S01

- Upstream site. 22 Figure 6

. Box model results for high (a) and low (b) flow r egime s in the u pper Allegheny River 23 s tudy d omain (Baseline includes mass from S01

- Upstream, POTW, and CFPP)

. 24 Figure 7

. Time series plot s of S05

- PDW1 quar terly mean (a) 2004

– 2014 rolling annual mean 25 THM concentration in finished drinking water in relation to the 80 ppb EPA standard, 26 (b) 2010

– 2014 significantly increasing THM concentration in finished drinking water 27 trend of ~ 6 ppb year - 1 , (c) 2010

– 20 14 trends of bromide and total organic carbon 28 (trend is not significant at α = 0.05)

. The box delineates the two quarters during the 29 2012 EPA field sampling campaigns. 30 31Figure 1. 32

33 Indiana 

## • 

# Legend

• Publicly Owned Sewage Treatment Works 

## .A. Commercial Waste Treatment Facility

• Coal Fired Power Plan t 

# 0 River Sampling Site 

## ® Public Dtinking Water In take

-- int erstate Highways

.. Allegheny River

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## LJ County Line



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## cy'V cyrp**cy~** 

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## cy'V cyrp cyOjFigure 4

. 40

41 200 (a) N on- I mpacted I m pac ted N on- I mpacted Impac t ed Non- I mpacted Impact ed

150 7l a. .!:!: 100 

# 1 1 

# 1 1 1

Q) "C E 

### e CXl <] 

# :**-- ----** **~- --** **---- --** **~** --------- 

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- 50 20 ( b )

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### • 5 

## •

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# ---$----~~-**--~--------**
-5 80 (c)

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### • 40

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0

# ---**-------** • -20

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4 'E 3 a. .!:!: Q) l§ "3 (/) <] 2 

# $

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___ _, _______ _

S03

- Downstrea m 1 -12 km 

## --- - --------

• 

# Q

•

S04

- Downstream 2

- 44 km 

## •

• 

# B

S05

- POW 1

-52 k m 

# - ·Figure 5. 42 43

S01 - Upstream S03 - Downstream 1 ~12 km S04 - Downstream 2 ~44 km S05 - PDW 1 ~52 km Impacted Non-impactedChloride/Bromide Ratio

100 200 300 400 500 Impacted Non-impacted Impacted Non-impacted

S06 - PDW 2 ~150 km
44Figure 6

. 45

46 

## (a) Low River Discharge Regime SOl-Upstream 

### + PO TW 

### + CFPP 448 kg Br dayl 135,498 kg Cl dayl S02-CWTF 202 kg Br dayl 18,208 kg Cl dayl



### (b) 

## High River Discharge Regime SOl-Upstream 

### + PO TW 

### + CFPP 973 kg Br dayl 492,534 kg Cl dayl S02-CWTF 159 kg Br dayl 17,323 kg Cl dayl SOS-PDWl (Actual) 703 kg Br dayl 167,034 kg Cl dayl

SOS-PDWl (Actual) 1475 kg Br dayl 671,763 kg Cl daylFigure 7 a. 47 482004_Q12004_Q22004_Q32004_Q42005_Q12005_Q22005_Q32005_Q42006_Q12006_Q22006_Q32006_Q42007_Q12007_Q22007_Q32007_Q42008_Q12008_Q22008_Q32008_Q42009_Q12009_Q22009_Q32009_Q42010_Q12010_Q22010_Q32010_Q42011_Q12011_Q22011_Q32011_Q42012_Q12012_Q22012_Q32012_Q42013_Q12013_Q22013_Q32013_Q42014_Q12014_Q22014_Q32014_Q4Total Trihalomethane (ppm)

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 Quarterly Average 80ppb Starndard Rolling Average (a)

49 50Figure 7 b. 512010_Q12010_Q22010_Q32010_Q42011_Q12011_Q22011_Q32011_Q42012_Q12012_Q22012_Q32012_Q42013_Q12013_Q22013_Q32013_Q42014_Q12014_Q22014_Q32014_Q4Total Trihalomethane (ppm)



### 0.04 0.05 0.06 0.07 0.08 THM = 0.0016 * (Quarter) + 0.0490 r 2 = 0.864 p < 0.0001 

### (b)

52Figure 7 c. 532009Q42010Q12010Q22010Q32010Q42011Q12011Q22011Q32011Q42012Q12012Q22012Q32012Q42013Q12013Q22013Q32013Q42014Q12014Q22014Q32014Q4Bromide (ppb)



### 0 50 100 150 200 250 300TOC (ppm)



### 0.0 1.0 2.0 3.0 4.0

Bromide TOC (c) Br - = -7.727 * (Quarter) + 165.3
r

2 = 0.474 p = 0.0045

54Table 1

. Summary of Allegheny River High ( April 30

- May 14, 2012 ) and Low ( July 5

- 19 & September 19

- October 4, 2012 ) 55 Discharge Isco Sample Results ( Kruskal Wallis Tests Indicate all Low Discharge Concentrations are Higher at all Sampling 56 Sites p < 0.0001 ). 57 58

59 60 S01

- Upstream S03

- Downstream1 S04

- Downstream2 S05

- PDW1 S0 6

- PDW 2 High Low High Low High Low High Low High Low

Spec

. Cond

.

( μS cm
- 1 ) n 15 31 14 31 13 30 15 26 15 28 Median 126 174 131 187 142 198 158 202 186 360 Mean 126 174 132 193 142 200 157 204 182 374 Range 116

- 143 150

- 194 112

- 154 154

- 262 127

- 157 168

- 243 144

- 171 177

- 250 152

- 215 271

- 608

Bromide

( ppb ) n 15 31 13 30 13 30 12 26 15 28 Median 25 72 28 88 32 78 38 85 35 132 Mean 26 72 34 101 31 85 36 87 35 142 Range 22

- 36 33

- 117 19

- 56 37

- 277 20

- 36 38

- 154 27

- 41 39

- 166 26

- 44 103

- 202

Chloride

( ppm ) n 15 31 14 31 13 30 15 26 15 28 Median 13.1 21 .0 13.8 22.5 14 .0 22.5 17 .0 23.5 15.9 29.6 Mean 13.5 20.8 14.7 23.8 14.3 23.3 17.3 23.6 15.9 30.4 Range 12.4

- 16.2 16.2

- 25.8 12.3

- 19.2 16.6

- 41.3 12.8

- 16.6 17.3

- 31.3 15.6

- 18.7 17.6

- 32 13.1

- 21.9 24.5

- 37.3

Sulfate ( ppm ) n 15 31 14 31 13 30 15 26 15 28 Median 10.3 7.5 11.9 8.3 11.6 8.9 11.1 9.5 27 .0 83.2 Mean 10.7 7.5 11.3 8.4 11.5 9 .0 11.3 9.6 28.7 82 .0 Range 9.7

- 13.5 6.8

- 8.6 3.7

- 12.8 7.8

- 9.7 10.2

- 12.8 8

- 11.7 10.3

- 13.1 8.5

- 10.8 23.3

- 39.9 47.6

- 128.8Table 2

. Summary of S pring ( April 30

- May 14, 2012 ) CWTF Discharge C ategorized Paired Isco S ample Results for Inter

- site 61 Analysis , and Kruskal Wallis Non

- parametric Hypothesis Test Results (bold are significant). 62 63
No Discharge Discharge No Discharge Discharge No Discharge Discharge S01

- Upstream S03

- Downstream1 S01

- Ups tream S03

- Downstream1 S01

- Upstream S04

- Downstream2 S01

- Upstream S04

- Downstream2 S01

- Upstream S05

- PDW1 S01

- Upstream S05

- PDW1

Spec

. Cond

. (μS cm
- 1 ) Paired n 7 7 6 7 7 7 Median 127 130 123 132 125 137 127 148 123 158 127 161 Mean 124 128 128 137 126 137 127 145 125 156 127 159 Range 116

- 131 112

- 137 116

- 143 122

- 154 118

- 138 127

- 151 116

- 143 130

- 157 118

- 138 144

- 166 116

- 143 148

- 171 p - Value 0.109 0.01 6 0.031 0.01 6 0.01 6 0.01 6

Bromide

(ppb) Paired n 6 7 6 7 4 7 Median 24 24 26 41 25 27 25 34 27 34 2 5 39 Mean 25 24 28 42 27 26 26 34 28 34 26 39 Range 22

- 30 19

- 28 24

- 36 26

- 56 22

- 36 20

- 32 23

- 32 32

- 36 23

- 36 28

- 39 23

- 32 36

- 41 p - Value 0.281 0.01 6 0.844 0 .01 6 0.25 0 0.01 6

Chloride

(ppm) Paired n 7 7 6 7 7 7 Median 13.3 13.3 13 15.0 13.1 13.1 13.6 15. 1 13 16.4 13.6 18 Mean 13.1 13.3 13.9 16.0 13.5 13.5 13.7 15.0 13.4 16.8 13.7 17.7 Range 12.6

- 13.6 12.3

- 13.9 12.4

- 16.2 13.6

- 19.2 12.4

- 16.2 12.8

- 15.8 12.6

- 16 13.2

- 16.6 12.4

- 16.2 15.6

- 18.4 12.6

- 16 16.8

- 18.7 p - Value 0.469 0 .01 6 1.000 0.01 6 0.01 6 0.01 6

Sulfate (ppm) Paired n 7 7 6 7 7 7 Median 10.1 11.9 10.3 11.9 10.9 11.5 9.9 11.6 10.6 11.1 9.9 11 Mean 10.5 10.7 10.4 11.9 11 11.7 10.5 11.4 10.9 11.3 10.5 11.3 Range 9.8

- 12.3 3.7

- 12.8 9.7

- 12.3 11.1

- 12.4 9.8

- 12.3 11.1

- 12.8 9.8

- 13.5 10.2

- 12 9.8

- 12.3 1 0.5

- 13.1 9.8

- 13.5 10.3

- 12.7 p - Value 0.375 0.031 0.313 0.156 0.813 0.109Table 3

. Summary of S ummer and F all ( July 5

- 19 & September 19

- October 4, 2012 ) CWTF Discharge Categorized Paired Isco 64 Sample Results for Inter

- site Analysis , and Kruskal Wallis N on - parametric Hypothesis Test Results (bold are significant). 65 66 No Discharge Discharge No Discharge Discharge No Discharge Discharge S01

- Upstream S03

- Downstream1 S01

- Upstream S03

- Downstream1 S01

- Upstream S04

- Downstream2 S01

- Upstream S04

- Downstream2 S0 1

- Upstream S05

- PDW1 S01

- Upstream S05

- PDW1

Spec. Cond. (μS cm
- 1 ) Paired n 20 9 17 9 15 9 Median 174 182 173 199 174 193 173 212 174 202 173 208 Mean 174 185 175 211 175 195 175 213 174 199 175 219 Range 151

- 194 164

- 229 150

- 194 178

- 262 161

- 194 18 1

- 216 150

- 194 188

- 243 161

- 194 181

- 222 150

- 194 197

- 250 p - Value <.001 0.004 <.001 0.004 <.001 0.004

Bromide

(ppb) Paired n 19 9 17 9 15 9 Median 78 74 71 134 77 71 71 102 80 71 71 107 Mean 75 77 74 155 75 74 74 107 80 77 74 112 Range 37

- 117 46

- 112 3 3

- 112 84

- 277 37

- 117 45

- 112 33

- 112 75

- 154 37

- 117 43

- 117 33

- 112 77

- 166 p - Value 0.731 0.004 0.927 0.004 0.454 0.004

Chloride

(ppm) Paired n 20 9 17 9 15 9 Median 21.3 21.3 21 27.1 21.3 21.9 21 24.7 21.9 22.2 21 25 Mean 21.1 21.4 21 29.5 21.2 22 21 25.6 21.6 22.6 21 26.4 Range 16.3

- 25.8 17.9

- 24.9 16.2

- 25.3 22.4

- 41.3 16.3

- 25.8 18.7

- 25.6 16.2

- 25.3 22

- 31.1 16.3

- 25.8 18.6

- 26.5 16.2

- 25.3 22.4

- 32 p - Value 0.729 0.004 0.089 0.004 0.107 0.004

Sulfate (ppm) Paired n 20 9 17 9 15 9 Median 7.6 8.2 7.4 8.3 7.6 8.8 7.4 9.1 7.6 9.5 7.4 9.7 Mean 7.6 8.3 7.3 8.6 7.6 8.9 7.3 9.3 7.6 9.7 7.3 9.6 Range 7 .0

- 8.6 7.8

- 8.8 6.8

- 7.6 7.9

- 9.7 7 .0

- 8.6 8

- 10.8 6.8

- 7.6 8.6

- 11.7 7 .0

- 8.6 8.5

- 10.8 6.8

- 7.6 9 .0

- 10 .0 p - Value <.001 0.004 <.001 0.004 <.001 0.004 67 68 69Table 4

. Summar y of all Isco S ample A naly sis at D ownstream S ites S03

- Downstream1 to S05

- PDW1 C ategorized as either CWTF 70 D ischarge or N on - D ischarge I mpacted , and Intra

- site CWTF Impact Analysis Results for those Species found to be 71 Significantly Higher

. 72 73 74 High River Di scharge Low River Discharge
Species Site Non

- discharge D ischarge One

- Sided t Appx CWTF Contribution Non

- discharge Discharge One

- Sided t Appx CWTF Contribution
S03

- Downstream1 Total n 7 7 0.19 21 10 <0.01 Mean ± SD 128 ± 8 137 ± 12 184 ± 16 212 ± 28 28 (15%) Spec. Cond. S04

- Downstream2 Total n 6 7 0.12 19 11 <0.01

(μS cm
- 1 ) Mean ± SD 137 ± 9 145 ± 10 192 ± 12 215 ± 20 23 (12%)
S05

- PDW1 Total n 8 7 0.17 17 9 0.01 Mean ± SD 156 ± 7 159 ± 9 196 ± 13 219 ± 23 23 (12%)
S03

- Do wnstream1 Total n 6 7 0.01 20 10 <0.01 Mean ± SD 24 ± 4 42 ± 11 18 (75%) 75 ± 20 154 ± 64 79 (105%) Bromide S04

- Downstream2 Total n 6 7 <0.01 19 11 <0.01

(ppb) Mean ± SD 26 ± 6 34 ± 1 8 (31%) 71 ± 20 110 ± 30 39 (55%)
S05

- PDW1 Total n 5 7 0.05 17 9 <0.01 Mean ± SD 32 ± 5 39 ± 2 7 (22%) 73 ± 23 112 ± 32 39 (53%)
S03

- Downstream1 Total n 7 7 0.02 21 10 <0.01 Mean ± SD 13.3 ± 0.6 16.0 ± 2.4 2.7 (20%) 21.1 ± 2.4 29.5 ± 6.1 8.4 (40%) Chloride S04

- Downstream2 Total n 6 7 0.03 19 11 <0.01

(ppm) Mean ± SD 13.5 ± 1.2 15.0 ± 1.2 1.5 (11%) 21.6 ± 2.3 26.1 ± 3.4 4.5 (21%)
S05

- PDW1 Total n 8 7 0.04 17 9 <0.01 Mean ± SD 16.8 ± 1.0 17.7 ± 0.7 0.9 (5%) 22.1 ± 2.6 26.4 ± 3.5 4.3 (19%)
S03

- Downstream1 Total n 7 7 0.48 21 10 0.15 Mean ± SD 10.7 ± 3.2 11.9 ± 0.5 8.3 ± 0.4 8.6 ± 0.6 Sulfate S04

- Downstream2 Total n 6 7 0.36 19 11 0.11 (ppm) Mean ± SD 11.7 ± 0.6 11.4 ± 0.6 8.9 ± 0.6 9.2 ± 0.9

S05

- PDW1 Total n 8 7 0.33 17 9 0.39 Mean ± SD 11.3 ± 0.9 11.3 ± 1.0 9.7 ± 0.7 9.6 ± 0.475 Table 5. Summary of all CWTF Impact Analysis Results at Downstream Sampling Sites S03

- Downstream1 to S05

- PDW1 on 76 Effluent Discharge Days

. 77 78 79 High River Discharge Low River Discharge Species Site Inter

- site Intra

- site Box Model Inter

- site Intra

- site Box Model Spec. Cond.

(μS cm
- 1 ) S03

- Downstream1

. . . . 28 (15%)

. S04

- Downstream2

. . . . 23 (12%)

. S05

- PDW1

. . . . 23 (12%)

. Bromide

(ppb) S03

- Downstream1 14 (50%) 18 (75%)

. 81 79 (105%)

. S04

- Downstr eam2 8 (31%) 8 (31%)

. 33 (45%) 39 (55%)

. S05

- PDW1 13 (50%) 7 (22%) 4 (16 %) 38 (51%) 39 (53%) 30 (44 %) Chloride

(ppm) S03

- Downstream1 2.1 (15%) 2.7 (20%)

. 8.5 (40%) 8.4 (40%)

. S04

- Downstream2 1.3 (9%) 1.5 (11%)

. 4.6 (22%) 4.5 (21%)

. S05

- P DW1

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