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Network Monitors Water Quality in Shale GasDrilling Region

High-pressure injection of water, sand and chemicals that fractureshale deposits deep underground to free trapped natural gas isemployed by drillers tapping the Marcellus shale beds, a geologicdeposit that stretches from central NewYork to Virginia and contains gas be-lieved to be worth hundreds of billionsof dollars.

Te process, called hydraulic frac-turing, or fracking, has raised concernsabout possible impacts on water qual-ity. ightly held shale gas like that inthe Marcellus shale deposits accountedfor 14 percent of the U.S. natural gassupply in 2009, according to the U.S.Energy Information Administration,which expects the gure to grow to45 percent of the nations gas by 2035if current trends and policies remainin place.

Hydraulic fracturing has beenpracticed since 1949 and has becomeextremely popular across the U.S. as gascompanies have increasingly focusedon hard-to-tap gas reserves, but littleinformation is available on its impacton surface and ground water supplies.Te Susquehanna River Basin Com-mission (SRBC) , based in Harrisburg,Penn., has established a 50-stationremote water quality monitoring net-work to provide continuous, real-timedata on local streams and rivers in ane ort to determine whether fracking isimpacting water quality in the basin.

Teres a lot of misinformationand questions about transparency re-

garding whats happening out there inthe real world as far as Marcellus gasdrilling, says om Beauduy, Deputy Executive Director of the SRBC. Tismonitoring network provides an excellent opportunity to providethe public with real data, and to serve as a sentinel for conditionsout there.

Water-Intensive Process o tap into shale gas in the Marcellus deposits, gas companies

drill vertical wells 5,000 to 9,000 feet deep, then turn their bitshorizontally for another 3,000 to 10,000 feet to maximize theamount of shale each wellhead can reach. Steel casing surrounded

by cement is designed to isolate the wellfrom groundwater as the sha travelsdeep into the bedrock. When the well iscomplete, explosive charges are pushedto the horizontal portions of the well tobreach the casing and begin the frac-turing process. A er the initial cracksare made in the brittle shale, fractur-ing uid is pumped down the well athigh pressure to further pry open thebedrock and free the gas.

Hydraulic fracturing is a water-intensive process3 to 5 milliongallons of frac uid are typically usedto fracture the deposits reached by anindividual well. Of that solution, morethan 90 percent is water. Sand, whichprops open the ssures in the fractureddeposit, comprises about 9 percentof the mix. Each drilling companysproprietary blend of other ingredients,

which can range from mineral oillubricants to pH adjustors to biocides,makes up the rest, accounting for 0.5to 2 percent of the volume, accordingto the U.S. Environmental ProtectionAgency (EPA).

Most of the known ingredients infrac uid are relatively benign, notesEPA, including products like mineraloil, guar gum and citric acid. However,others such as diesel fuel, ethyleneglycol, and the biocide glutaraldehyde

can present a signi cant environmentalconcernin the Marcellus wells, up to10 percent of the frac uid returns tothe surface within 30 days of injection

as owback.As many as 400 trucks serve a well during the fracturing pro-

cess, hauling frac uid and produced water to and from the drillpad. Wastewater ponds may also be constructed for temporary storage. Both raise concerns over the danger of spills into local

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The boom in drilling in the gas-rich Marcellus shale hashighlighted the need for data on the impact of the hy- drofrac wells on local streams. (Photo: Andrew Gavin)

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A network of 50 remote water quality monitoring sta- tions is designed to cover a wide range of locationsand detect frac uid spills. (Photo: Andrew Gavin)

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streams, notes Andrew Gavin, Manager of SRBCs Monitoringand Protection Program.

Designing the Network Building on SRBCs experience with a drinking water quality

monitoring network established almost a decade ago, Gavin andhis colleagues developed a plan to deploy sondesrugged probesthat collect and transmit information on water qualityfor long-term, continuous monitoring at 50 sites in the Susquehanna basinwhere it overlies Marcellus shale in Pennsylvania and New York.

Each station consists of a YSI 6600 V2-4 multiparametersonde in a protective PVC housing tethered to the streambank and connected to a data platform. Dataloggers are connected tocell modemsor if a cell signal is unavailable, a satellite transmit-terand powered by a solar panel.

Drillers have to disclose the contents of their long-secretfrac uid formulations, but monitoring for speci c contaminantsin the eld is not viable. Instead, SRBC focused on monitoringparameters that would indicate a likely spill of either a salinesolution or mineral-rich deep groundwatertemperature, con-ductance, pH, dissolved oxygen (DO), and turbidity. Monitor-ing those parameters as well as water level can also yield insighton other phenomena such as acid rain or turbidity from stormevents, Gavin notes.

Te Commission chose three types of monitoring sites, saysGavinstreams close to existing wells or truck routes, reacheswhere infrastructure and other conditions make it likely thatwells will be established nearby, and more pristine streams inhighly forested areas outside the expected drilling zones. Somestations also monitor high-value watersheds such as municipalwater supplies or popular recreation areas. o take full advantageof the chance to gather new data on local watersheds, the network sites are located in areas not already covered by U.S. GeologicalSurvey monitoring e orts

Te range of locations should provide a useful combinationof baseline data, evidence of changes, and insight into local streamsystems that have not been well-studied in the past, says Gavin.

Te size of the watershed connected to each site was a criti-cal decision.

In looking at some of the critical criteria for choosinglocations, the question became, what would be the most likely volume of a wastewater spill, leak or breach wed be dealingwith? Gavin notes.

Breaches or leaks from wastewater storage ponds near wellspresent a signi cant water quality threat. But smaller spills canalso be a problem. For instance, an average tanker truck car-ries 5,000 gallons. A spill of that size could easily be diluted ina large watershed, or get ushed past a monitoring station soquickly that it would be missed if the network protocols werentestablished properly.

We conducted bench tests with YSI equipment in the lab

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Y S I Environmental Pure Data for a Healthy Planet. Application Not

and simulated frac wastewater, says Gavin. We determined thatif we targeted watersheds no greater than 60 to 80 square miles,they generally have ows where we could detect changes in waterquality if wastewater was introduced into the stream. Most of the monitored streams run below 100 cubic feet per second (cfs)80 to 90 percent of the time, and ow in the single digits or teensduring low- ow conditions.

We have all of our stations taking observations every veminutes, Gavin adds. It goes back to what we de ned as ourmost probable scenarioa volume of 5,000 gallons carried in

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Matt Shank of the SRBC installs a water quality sonde in a to endure winter and summer conditions. (Photo: Heather H

Jake Wilson (left) and John Balay of the Susquehanna RivCommission install a water quality monitoring station on H

Creek. (Photo: Andrew Gavin)

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a truck. With a plume of that concentration, we could detect atleast some part of itthe beginning, middle or endwithin a

ve-minute interval.If key parameters surpass normal levels, the station triggers

an alarm to prompt an investigation.Te system was put to the test in May 2010 when a wastewater

pit liner breached, releasing frac owback water near Bobs Creek in western Pennsylvania. Te drilling company reported the

breach to state o cials, and SRBC paid special attention to datacoming from a sonde seven to eight miles downstream of the spill.We were pleased that it wasnt a large volume, but we were

able to see a distinctive breakthrough curve, Gavin says. Youcould see the rise in conductance for about 24 hours, then thefall as it moved through the system. In that sense, we had a littletest to see if we could pick up an event.

Logistical ConsiderationsSome logistical considerations also have to be taken into ac-

count. For instance, notes Gavin, stations must be situated so themonitoring instruments stay submerged even during low- owconditions, and can be placed deep enough to stay below theice during the winter. Te channel should also provide enough

ow to prevent leaves and sediment from building up aroundthe sonde, he adds.

Access is another big logistical concern. SRBC has built itsmonitoring stations on both public and private land. Each hasits bene ts and challenges.

Siting a station on public land is a simple matter of coordinat-ing with whichever state agency controls the property, thoughGavin notes that some state-owned areas were a bit too public,raising concerns about vandalism in areas with heavier tra c.Stations on private land can be more secure, but working withlandowners can have its challenges.

You have to have private landowners agree to participate,notes Beauduy. Several landowners stepped up immediately.Others were concerned about the stations being near them, ordidnt want people coming across their property.

Reliability is Key Every six to eight weeks, SRBC sta visit each monitoring

station to rotate the sonde with a lab-calibrated replacement, con-duct eld calibration for the replacement instrument, and bringthe long-deployed sonde back to the lab for calibration, cleaningand QA/QC before its redeployed at another station. Durability and stability are key to making the system work smoothly.

Te YSI sondes have been very reliable, with even lowermaintenance needs than expected, Gavin says. Teyre very versatile and durable for eld deployment. I was familiar with YSIproducts from when I worked for USGS back in the early 90s,and we had quite a comfort level with the companys sondes fromour drinking water monitoring system back in 2003.

During the regular maintenance visits, technicians also col-lect water samples to be lab-tested for pH, chloride, barium, totaldissolved solids ( DS), sulfate and total organic carbon ( OC)

a er each visit. Four times a year, water samples are collectedfor a detailed analysis including calcium, magnesium, sodium,potassium, nitrate, carbonate and bicarbonate alkalinity, carbondioxide, bromide, strontium, lithium, and gross alpha and betaa thorough workup that better characterizes the in uence of groundwater in the stream or indicates the presence or absenceof owback wastewater. While on-site, the team also uses Son ek Flow rackers to measure stream ow.

Fresh Data Round the Clock Te sondes collect observations on a ve-minute interval,

and transmit collected data to SRBCs o ce every two to fourhours. Data is imported into SRBCs database and within a fewminutes is posted without correction (and labeled provisional)for public access at http://mdw.srbc.net/remotewaterquality/ .

A year a er the rst stations went online, says Gavin, wereat 10 million observations, but even at that level, the le size isntthat great. Analysis work is generating four-hour averages ordaily averages, and well be running through corrections basedon calibration dri .

A er compiling the rst years data, SRBC is getting readyto release its rst data summary. Gavin notes that more data willbe required to determine if and how fracking is a ecting waterquality in the basin. However, a preliminary analysis shows greatbaseline data for the station sites, and unexpected results fromsome areas are prompting further study, he says.

Some stations were keeping a closer eye on because of theway the trends areit may take more analysis to understandwhats going on, Gavin explains. Were also collecting supple-mental data on geochemistrywater samples for lab analysestohelp characterize the natural conditions and put the continuousdata into context.

A broad array of users has accessed the data. We have ev-erybody from just your private citizen to locals who are part of civic or watershed groups to those more speci c citizen groupsorganized around Marcellus, says Gavin. Te state uses it as wellto keep an eye on conditions. Te industry itself has been watch-ing the data. And theres been a lot of interest from universities.

Te Commission posts a glossary of key water quality termsand explanations on its web site, though Gavin says most visitorsto the networks web site are familiar with water quality conceptsand what the data means.

Real-time data, long-term trend monitoring and spillalarms will all be important in monitoring surface water in theSusquehanna River Basins Marcellus shale region. But the abil-ity to collect long-term, continuous data and post it online forthe world to see takes the monitoring network to an even higherlevel, says Beauduy.

Tis is a way to provide value-added service to our membercommissions, especially on something thats somewhat contro- versial, he says, in a way that lets the science speak for itself andlets the public have access to the data in a transparent manner.

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