Long-Term Variability in Methane in Domestic Water Wells in Northeast Pennsylvania

Transcription

1 GROUNDWATER & ENVIRONMENTAL SERVICES,INC. Denise Good, PE Richard Wardrop, PG Debby Yost Bert Smith, PG Long-Term Variability in Methane in Domestic Water Wells in Northeast Pennsylvania Charles Whisman, PE Chief Technology Officer GES

2 Study Background Methane (CH 4 ) Prevalence and Variability Lack of water well construction standards General findings from extensive pre drill data Water well samples collected (29 211): 11,312 Methane detections (>.26 mg/l): 2,74 (24.2%) >.26 to 3 mg/l: 2,64 (18.2%) >3 to 7 mg/l: 287 (2.5%) >7 to 2 mg/l: 27 (2.4%) >2 mg/l: 119 (1.1%) Limited understanding of natural methane variation and occurrence related to complaints

3 Long-Term Monitoring: Domestic Wells Address gaps in understanding Quantify natural variation in methane levels Relevance Significant importance in assessing natural methane variation and occurrence Study Objective Gain understanding of long term variability of methane in domestic water wells and correlation to other parameters, such as well usage and pumping

4 Study Design 11 domestic water wells Pre drill (baseline) sampling data used to select sites 3 categories of baseline dissolved methane levels Low: < 5 mg/l Medium: 5 to 15 mg/l High: > 15 mg/l 3 4 wells from each category Depths: 4 to 3 feet Located across Bradford and Sullivan Counties in Northeastern Pennsylvania 12 months of monitoring

5 Study Locations

6 General Outline: Study Parameters Local and Regional Geology Supply Well Construction and Conditions Manual Water Sampling for Laboratory Analysis No dissolved methane sensor available Continuous Remote Monitoring Headspace gas parameters (CH 4, CO 2, O 2 ) Water well parameters (water levels, turbidity) Weather Parameters Data logged and manually downloaded (temperature, barometric pressure, humidity, wind, precipitation)

7 Preparation of Study Water Wells Water treatment system installation or upgrade Borehole geophysics Downhole InSitu water quality logging (ph, temp., cond.) Supply well power re configuration Jet pumps replaced with submersible pumps (2 wells)

8 Remote Real-Time Monitoring Parameters Well Headspace CH 4 (1 ppm to 1% volume, 2 sensors) O 2 CO 2 Gas flow Gas pressure Down Well Water level Turbidity Pump flow rate

9 Real-Time Data Data logged every minute Transferred via cell modem Uploaded to custom software Uploaded to secure website Choose location via list or map Graphs, statistics, raw data Data integrated with Microsoft Access, EarthSoft EQuIS and other data management tools 9

10 Equipment Setup Equipment customized at each site Headspace gas drawn from ~2 feet below well grade using sample pump Weather Stations at 6 locations Barometric pressure Precipitation Temperature Wind Humidity

11 Water Type and Geologic Setting Location Mapped Bedrock Formation Water-Type MB Lock Haven Sodium - Bicarbonate T Lock Haven Sodium - Bicarbonate B Lock Haven Sodium - Bicarbonate DV Catskill Sodium - Bicarbonate/Chloride G Lock Haven Sodium/Calcium -Bicarbonate V Catskill Sodium/Calcium -Bicarbonate N Catskill Sodium/Calcium -Bicarbonate TB Lock Haven Sodium - Chloride H Catskill Sodium - Chloride R Lock Haven Sodium - Chloride EH Catskill Calcium/Sodium - Bicarbonate

12 Analytical Data Assessment Tracking data to determine relationships with methane and key dissolved constituents: Sulfate Chloride Methane and Sulfate in Water: Site R Barium Lithium Strontium

13 Variation in Dissolved Methane in Groundwater Dissolved Methane Variability: Site EH EH Location Methane, mg/l Baseline Sample

14 Dissolved Methane Variation: Low Level (<5 mg/l) Baseline Baseline Baseline Baseline

15 Dissolved Methane Variation: Medium Level (5-15 mg/l) Baseline Baseline Baseline

16 Dissolved Methane Seasonal Variation: Medium Level (5-15 mg/l) 3 25 Number of Samples Spring: 48 Summer: 21 Fall: 23 Winter: 48 Methane, mg/l Spring Summer Fall Winter Season

17 Dissolved Methane Variation: High Level (>15 mg/l) Baseline Baseline

18 Dissolved Methane Seasonal Variation: High Level (>15 mg/l) 7 6 Number of Samples Spring: 39 Summer: 14 Fall: 9 Winter: 19 5 Methane, mg/l Spring Summer Fall Winter Season

19 Turbidity vs Water Level: Site B 2 Turbidity, NTU Turbidity Water Level 4 2/4/212 : 2/4/212 12: 2/5/212 : 2/5/212 12: 2/6/212 : 2/6/212 12: 2/7/212 : Water Level Change from Initial Static, ft

20 Headspace Methane vs. Water Level Change in 24 Hours EH Location Headspace Methane vs Water Level: 24 Hours (Site EH) 35 Methane, ppm /5/211 6: 12/5/211 8:24 12/5/211 1:48 12/5/211 13:12 Headspace Methane 12/5/211 15:36 12/5/211 18: Water Level Change 12/5/211 2:24 12/5/211 22:48 12/6/211 1:12 12/6/211 3: /6/211 6: Water Level Change from Initial Static, ft

21 Observing Methane Trends over Different Time Intervals Headspace Methane vs. Water Level Change in 24 Hours EH Location 55 Headspace Methane Water Level Change 1 Day Duration 1 Headspace Methane vs. Water Level Change in 72 Hours EH Location 55 Headspace Methane Water Level Change 3 Day Duration 1 Methane, ppm Water Level Change from Initial Static, ft Methane, ppm Water Level Change from Initial Static, ft /3/212 : 6/3/212 12: 7/1/212 : /3/212 : 7/1/212 : 7/2/212 : 7/3/212 : Methane, ppm 55 Headspace Methane Headspace Methane vs. Water Level Change in 7 Days EH Location Water Level Change 7 Day Duration Water Level Change from Initial Static, ft /3/212 : 7/1/212 : 7/2/212 : 7/3/212 : 7/4/212 : 7/5/212 : 7/6/212 : 7/7/212 :

22 Headspace Methane vs Water Level: Site MB Methane, ppm Headspace Methane Depth to Water Fracture 5/3/213 : 5/4/213 : 5/5/213 : 5/6/213 : 5/7/213 : Depth to Water (feet below grade)

23 Headspace Methane vs. Water Level Change in 6 Hours DV Location Headspace Methane vs Water Level: 6 Hours (Site DV) 14 Methane, ppm Headspace Methane Water Level Change 14 5/12/212 12: 5/12/212 13:12 5/12/212 14:24 5/12/212 15:36 5/12/212 16:48 5/12/212 18: Water Level Change from Initial Static, ft

24 Comparison Between Groundwater Methane vs. Headspace Methane Over Time Headspace Methane vs Dissolved Methane: Site EH 12 Groundwater Methane 12 1 Headspace Methane Groundwater Methane mg/l Headspace Methane ppm /12/211 1/24/211 11/1/211 11/8/211 12/1/211 12/15/211 12/28/211 1/12/212 1/26/212 2/9/212 2/23/212 3/6/212 3/22/212 4/2/212 4/19/212 5/3/212 5/17/212

25 Variability in Headspace Methane over Time: Site EH January 212 Methane, ppm April 212 July 212 July 212 October 212

26 Headspace Methane vs Water Temp vs Air Temp vs Water Level: Site G.5% Vol = 5, ppm = 1% LEL Note: All data is preliminary

27 Methane vs Carbon Dioxide Well Headspace: Site MB Methane, % Volume Carbon Dioxide, ppm.5% Vol = 5, ppm = 1% LEL Note: All data is preliminary

28 Preliminary Findings Methane occurs naturally and highly variable: Spatially and temporally Weather Man induced changes (water well pumping) Single pre drill baseline methane sample may not represent the full range of natural variability Natural methane levels (headspace and dissolved) may be influenced by pumping or water level fluctuations Water level declines (pumping or natural) may increase natural methane headspace concentrations Natural methane concentrations may vary seasonally

29 GROUNDWATER & ENVIRONMENTAL SERVICES,INC. Denise Good, PE Richard Wardrop, PG Thank You! Debby Yost Bert Smith, PG Long-Term Variability in Methane in Domestic Water Wells in Northeast Pennsylvania Charles Whisman, PE Chief Technology Officer GES