Evaluation of Geology and Water Well Data Associated with the EPA Hydraulic Fracturing Retrospective Case Study, Bradford County, PA

Transcription

1 Evaluation of Geology and Water Well Data Associated with the EPA Hydraulic Fracturing Retrospective Case Study, Bradford County, PA Deborah Watkins, P.E. and Thomas Cornuet, P.G. July 24, M-0159

2 Discussion Topics for Today s Presentation Background Information Hydrogeology and Historical Water Quality in Bradford Co., PA Historical and Baseline Groundwater Data Evaluation Study Well Evaluation Conclusions 2

3 Background Information EPA is conducting a retrospective hydraulic fracturing study in Bradford and Susquehanna Cos. - During the first sampling event, EPA collected samples from 37 groundwater locations in October and November of A second sampling event was conducted in April 2012; data are currently being evaluated and are not included in this presentation A third party contractor collected split samples with the EPA for accessible sample locations; many sample locations could not be accessed because: - EPA deemed confidential - Property owner would not allow access Certified commercial laboratories used EPA approved analytical methods 3

4 Objective: - Evaluation of analytical data for 15 Bradford Co, PA groundwater sample locations to determine if they have been impacted by unconventional shale gas development Scope: - Evaluate hydrogeology and summarize historical water quality data in Bradford Co. - Compare EPA Study Well data to historical water quality and available pre-drill/baseline data sets - Identify exceedances of EPA and PADEP water quality screening criteria for historical and baseline data sets Presentation: WESTON Evaluation - Provides a brief overview of evaluation including methane 4

5 Hydrogeology and Historical Water Quality in Bradford Co, PA 5

6 Bradford County Geology 6

7 Bradford Co. Hydrogeology and Geochemistry USGS Report (Williams et al, 1998) Prepared prior to commercial unconventional shale gas development in Bradford Co. A comprehensive study of the hydrogeology and groundwater quality of Bradford, Potter, and Tioga Cos. conducted by the USGS beginning in 1983 Describes hydrogeologic conceptual model and provides a large and thorough historical/background database of water quality data for unconsolidated stratified drift glacial deposits and the Lock Haven and Catskill bedrock formations 7

8 Catskill and Lock Haven Formations Catskill Formation : 9 EPA split sample locations Lock Haven Formation: 6 EPA split sample locations Devonian-age interbedded shale, siltstone, and sandstone Catskill underlies much of the uplands of Bradford Co. and Lock Haven underlies most of the major valleys Lock Haven water typically considered hard and often naturally high in arsenic, barium, chloride, iron, manganese, sodium, and TDS 8

9 Bradford Co. Hydrogeology Restricted Groundwater Flow Zones Restricted groundwater flow zones: - Naturally occurring - Water quality is affected by aquifer formation geochemistry, water residence time, recharge, and depth of occurrence - Highly mineralized or poor water quality (often Na-Cl or Na-HCO 3 water types) - Often exhibits elevated hydrogen sulfide and methane concentrations Typically found in major stream and river valleys, mostly in Catskill and Lock Haven bedrock formations Water quality typically contains barium, chloride, iron, manganese, radium, sodium, strontium, and TDS which commonly exceed screening criteria 9

10 Historical and Baseline Groundwater Data Evaluation 10

11 Databases Database No. of Wells* Sample Dates Classifications** National Water Information System (NWIS) inorganics National Uranium Resource Evaluation (NURE) - inorganics USGS Water Resources Report 68 (Wms 1998) - inorganics Baseline Data (near sample locations) inorganics and BTEX October ,773 9/17/2009 1/10/2012 Catskill, Lock Haven Formations Catskill, Lock Haven Formations Detailed geologic classifications*** Divided into Central, Eastern, and Western Regions 11 *Includes only wells in Bradford Co. in the Catskill and Lock Haven Formations. **Geologic units assigned based on bedrock occurrence; geographic regions used for retrospective study wells. ***Includes Catskill Formation, Lock Haven Formation, stratified drift (confined and unconfined), and restricted flow zone.

12 Baseline Sampling Program Near Retrospective Wells 12

13 Geologic Classification for NURE, NWIS, and Study Wells PA Statewide Groundwater Information System (PAGWIS) query cross referenced 83% of NWIS wells PA Geologic Survey (PGS) spatial query used to classify remaining wells (17% of NWIS; all of NURE) PGS spatial query used to identify wells potentially within stratified drift (within stratified drift footprint and < 120 feet deep) If depth not known, defaulted to bedrock formation 13

14 Parameter Screening Levels for Select Parameters PADEP Act 2* EPA MCL EPA SMCL EPA Regional** Aluminum (mg/l) Arsenic (mg/l) Chloride (mg/l) 250 Iron (mg/l) Lead (mg/l) *** Lithium (mg/l) Manganese (mg/l) ph (ph units) TDS (mg/l) 500 Turbidity (NTU) 5 Total Coliform (col/100 ml) 1 *Residential use wells < 2,500 mg/l TDS **Screening levels for tap water (chronic) ***Action level 14

15 Parameters that Frequently Exceeded Water Quality Screening Criteria in Historical and Regional Baseline Databases (pre 2006) 15 Parameters Historical USGS Databases Baseline Database Aluminum Arsenic Barium Chloride/TDS (1) Iron Lead Lithium Limited data Manganese ph Sodium Strontium (1) Limited data Turbidity Limited data (1) In the Restricted Flow Zone

16 Comparison of Baseline Methane Levels with Screening Levels of 3 mg/l, 7 mg/l, and 20 mg/l Region Number of Samples Number of Detections % of Detections Maximum (mg/l) Mean (mg/l) Median (mg/l) Total Number > 3 mg/l Total Number > 7 mg/l Total Number > 20 mg/l Central Region % Eastern Region % Western Region %

17 Study Well Evaluation 17

18 Study Well Parameters Evaluated Study well data included pre-drill baseline samples, additional post-drill samples, and EPA retrospective split samples All study well data were compared to Applicable Water Quality Criteria - Heavy Metals (As, Ba, Fe, Mn, etc.) - Inorganics (Cl, TDS, Na, SO 4, etc.) - Organics (VOCs, SVOCs, etc.) For 12 groundwater locations, post-drill data were compared to regional baseline data for those sample locations For all 15 groundwater locations, available data were compared to historical USGS databases and regional baseline data 18

19 Time Plot of Chloride - Property Owner E (115 ft. Well) 19

20 Time Plot of Iron - Property Owner E (115 ft. Well) 20

21 Time Plot of Manganese - Property Owner E (115 ft. Well) 21

22 Time Plot of Sodium - Property Owner E (115 ft. Well) 22

23 Time Plot of TDS - Property Owner E (115 ft. Well) 23

24 Time Plot of Barium - Property Owner E (115 ft. Well) 24

25 Time Plot of Methane - Property Owner G 25

26 Time Plot of Methane - Property Owner H 26

27 Time Plot of Methane Property Owner I 27

28 Conclusions 28

29 Conclusions The 15 groundwater sample locations do not appear to be impacted by natural gas drilling or production activities - For all 15 groundwater sample locations, water quality data was typical of water quality concentrations in historical USGS databases and regional baseline data - There are no significant increases in inorganic and other water quality parameters when comparing data from each of the 12 study wells with available baseline data - There are no significant increases in dissolved methane when comparing data from each of the 12 study wells with available baseline data - Few organics were detected - None of these are attributable to natural gas production activities or exceeded applicable drinking water standards 29 Similar to the historical/baseline databases, the15 sample locations contained aluminum, arsenic, barium, chloride, iron, lead, lithium, manganese, ph, sodium, strontium, and turbidity; in several instances, these naturally occurring concentrations exceeded EPA and/or PADEP screening criteria

30 References Boyer, EW, Swistock, BR, Clark, J, Madden, M and DE Rizzo, The Impact of Marcellus Gas Drilling on Rural Drinking Water Supplies, Center for Rural Pennsylvania, March Focazio, MJ, Welch, AH, Watkins, SA, Helsel, DR and MA Horn, A Retrospective Analysis on the Occurrence of Arsenic in Ground-Water Resources of the United States and Limitation in Drinking-Water-Supply Characterizations, Water Resources Investigations Report , USGS. Low, DJ. and DG Galeone, Reconnaissance of Arsenic Concentrations in Ground Water from Bedrock and Unconsolidated Aquifers in Eight Northern-Tier Counties of Pennsylvania, Open-File Report , USGS. Swistock, BR, Clemens, S and WE Sharpe, Drinking Water Quality in Rural Pennsylvania and the Effect of Management Practices, Center for Rural Pennsylvania, January Watkins, DM, and TS Cornuet, Evaluation of Geology and Water Well Data Associated with the EPA Hydraulic Fracturing Retrospective Case Study, Bradford County, Pennsylvania, April _CHK_WestonStudy_BradfordPA.pdf Williams, JE, Taylor, LE and DJ Low, Hydrogeology and Groundwater Quality of the Glaciated Valleys of Bradford, Tioga, and Potter Counties, Pennsylvania, PA Geological Survey and USGS, Water Resources Report Williams, JH, Evaluation of Well Logs for Determining the Presence of Freshwater, Saltwater and Gas above the Marcellus Shale in Chemung, Tioga, and Broome Counties, New York, USGS, Scientific Investigations Report

31 Thank You! Questions? 31