HIGH VACUUM MULTI-PHASE EXTRACTION – CASE STUDIES MWCC CONFERENCE JULY 2019
High Vacuum Multi-Phase Extraction § Soil vapor and groundwater extraction and treatment system § Truck Mounted § 450 CFM Air Flow § 29 Inches Hg Max Vacuum § 50 GPM Water Extraction § Can extract from up to 6 wells at a time.
High Vacuum Multi-Phase Extraction Case Studies § Shallow LNAPL Zone § Deep Complex LNAPL Zonese
Shallow LNAPL Zone § Active Gas Station (Since Prior to 1988) § 3-12,000 gallon USTs § Former Gas Station and USTs § 2-4,000 gallon, 1-300 gallon waste oil UST § Removed in 1988 – Separate release R1988 given NFA in 2014 § Known Release – 2008 § Geology § Silty Clay § Bedrock - 8-18 feet bgs § Groundwater flow to N/NW
LNAPL § Known Release (2008) – ~4500 Gallons – North dispenser § Measured in 3 Existing Wells After Release § MW-9, MW-10, MW-16 – Maximum thickness – 4.15 feet – MW-10 § Recovery Wells Installed – November 2008 § Measured in all 5 RWs – Maximum thickness – 4.06 feet – RW-2 § Generally measured between 4.3 and 12.55 feet btoc (Intermittent)
Previous LNAPL Removal § LNAPL Gallons Removed Unknown § 10 MDPE events – October 2008 – February 2009 – 7,033 Gallons of Groundwater § Passive Recovery – May 2009 – October 2012 – ~44 gallons § Reduction in Thickness – LNAPL Remained in MW-9, MW-10, MW-16, RW-2, RW-3, RW-4, RW-5
High Vacuum Multi-Phase Extraction January 2018 – March 2018 (49 Days) § Measured LNAPL (Intermittent) § Prior to HVDPE: MW-9, MW-10, RW-4, RW-5 § Additional During HVDPE: MW-23 § Six Extraction Wells (Different Combos, 4 Wells at a Time) § MW-10, MW-16, RW-2, RW-3, RW-5, RW-6
High Vacuum Multi-Phase Extraction Considerations § Measured Depth to LNAPL § Beginning (4 wells): 7 – 11.5 feet btoc § During (1 additional well): 8.5 – 9.5 feet btoc § Total Depth of Wells with LNAPL § 11 – 14 feet § Stinger Placement § Initially – DTW/LNAPL or 1 foot below § Final – Bottom of well
High Vacuum Multi-Phase Extraction – Results § System Parameters § Air Flow: 125-167 CFM o Increase as saturated zone exposed (vapor increase) and LNAPL reaches MEP § Vacuum: 15-18 Inches Hg o Increase as saturated zone exposed (vapor increase); Consistent as LNAPL reaches MEP § Influent Conc: ~1,300 ppmv – 9,900 ppmv o High when saturated zone exposed § 131,590 Gallons of Groundwater Removed (2,676 Gallons/Day) § Avg. 1653.26 (Equivalent) Gallons of Hydrocarbons Removed (33.8 Gallons/Day) § Drawdown ROI/Vacuum ROI of Up to 60 Feet
3/11/18 0:00 3/10/18 0:00 3/9/18 0:00 3/8/18 0:00 3/7/18 0:00 3/6/18 0:00 3/5/18 0:00 3/4/18 0:00 3/3/18 0:00 Saturated Zone Exposed/ 3/2/18 0:00 3/1/18 0:00 2/28/18 0:00 Removal of LNAPL 2/27/18 0:00 2/26/18 0:00 2/25/18 0:00 2/24/18 0:00 2/23/18 0:00 2/22/18 0:00 2/21/18 0:00 Total Inlet Vapor Concentration Vs. Time 2/20/18 0:00 2/19/18 0:00 2/18/18 0:00 2/17/18 0:00 2/16/18 0:00 2/15/18 0:00 2/14/18 0:00 and Stinger Depth 2/13/18 0:00 2/12/18 0:00 2/11/18 0:00 Well Change High Vacuum Multi-Phase Extraction – Results 2/10/18 0:00 2/9/18 0:00 Change 2/8/18 0:00 2/7/18 0:00 2/6/18 0:00 Dilution 2/5/18 0:00 2/4/18 0:00 2/3/18 0:00 2/2/18 0:00 Saturated Zone Exposed 2/1/18 0:00 1/31/18 0:00 1/30/18 0:00 1/29/18 0:00 1/28/18 0:00 1/27/18 0:00 Stinger Depth 1/26/18 0:00 1/25/18 0:00 1/24/18 0:00 Change 1/23/18 0:00 1/22/18 0:00 1/21/18 0:00 1/20/18 0:00 1/19/18 0:00 1/18/18 0:00 1/17/18 0:00 1/16/18 0:00 12,000 10,000 8,000 6,000 4,000 2,000 0 Vapor Inlet Concentration (ppmv) § Decreasing Trend at End § Saturated Depths – SVE Trend – Saturated zone § No LNAPL Remains in Dewatered (Dry wells) § Stinger Depth, Well § Periodic Increasing § LNAPL Mobilized Combinations Wells
High Vacuum Multi-Phase Extraction – Water Levels MW-16 MW-23 1/16/2018 1/20/2018 1/24/2018 1/28/2018 2/1/2018 9 1/16/2018 1/20/2018 1/24/2018 1/28/2018 2/1/2018 6 § Observation Wells 9.5 6.5 7 Depth to Water (feet) § Dropped up to 10 Depth to Water (feet) 7.5 3.34 feet 8 10.5 8.5 11 9 9.5 11.5 10 12 § Extraction Wells 10.5 MW-26 RW-5 § Dropped > 1 foot 12/11/17 0:00 1/20/18 0:00 3/1/18 0:00 4/10/18 0:00 1/16/2018 1/20/2018 1/24/2018 1/28/2018 2/1/2018 (1 week later) 8 10 10.5 8.5 11 Depth to Water (feet) Depth to Water (feet) 11.5 9 12 9.5 12.5 13 10 13.5 14 10.5 14.5 11 15
May 2009 – October 2016 October 2008 – February 2009 March 2018 – April 2019
Deep Complex LNAPL Zones § Active Gas Station (Since 1950) – 1- 30,000 Gallon Compartmentalized UST § Former UST Basin § 1-4,000 gallon, 2-6,000 gallon and 1-8,000 gallon (Removed 1995) § Impact found in 1995 § Unknown release date and amount § Geology § Silty clay to sandy clay with sand and gravel lenses throughout § Bedrock – 25-45 feet bgs § Groundwater flow variable
LNAPL § First discovered in 1999 in MW-2 (2.0 feet) § Historically identified in 11 On-Site and Off-Site Wells (Intermittent) § Maximum historical thickness in MW- 15, July 2010 – 7.51 feet, DTW – 28.65 feet § Generally measured at depths of between 21 feet – 35 feet in wells (depending on location)
Previous LNAPL Removal § ~213 gallons removed since 1999 § Manual Recovery (30+) – ~ 21 gallons § Mobile Dual Phase Extraction (MDPE) – 5 events between 2012 and 2016 – ~183 gallons § Active Skimming System (Pilot on MW-15 and MW-16) – Between 2013 and 2015 – ~9 gallons § Periodic Passive Recovery § > 50% reduction in MW-2 and MW-15 – Greater than 1 foot LNAPL remained onsite
Laser Induced Fluorescence (LIF) Survey – 2012 ~5 – 10 feet *Some areas of 20 feet ~25 – 35 feet § 21 borings completed – 31 to 42 feet (refusal) § Multiple discontinuous zones (shallow and deep); above and below groundwater surface § Monitoring/Recovery wells screened in shallow and deep LNAPL zones § Estimated volume of LNAPL body – 2,332 gallons
7-Day Pilot Test (December 2016) § Considerations and Plan § LNAPL Measured in MW-12, MW-26, RW-5 (December 2016) § LNAPL Zones (LIF Data) § Extraction Wells (Six at a Time, Different Combos) o MW-2, MW-12, MW-15, MW-16, MW-26, RW-5
7-Day Pilot Test Considerations § Wells generally screened in deep LNAPL zone § LNAPL Zones § Shallow (Limited): 5-10 feet bgs § Deep: 25-35 feet bgs § Measured Depth to LNAPL § Role of Stinger Depth § MW-12 – 31.28 ft, TD – 35 ft § Initial – DTW/LNAPL in § MW-26 – 31.06 ft, TD – 40 ft Wells § RW-5 – 24.75 ft, TD – 37 ft § Final – Bottom of LNAPL Zone/Bottom of Well
7-Day Pilot Test – Results § System Parameters § Air Flow: 34 – 78 SCFM (Highly Variable) o Initial highest air flow (multiple wells) o Decrease with reduction in wells and as saturated zone exposed § Vacuum: 21 – 25 Inches Hg o Remained consistent § Influent Conc: ~4,000 – 13,000 ppmv (Some Dilution) o High when saturated zone exposed § 26,920 Gallons of GW Removed and Treated § Average of 203.36 Gallons of Hydrocarbons Removed § Water Levels (Observation and Extraction Wells) – Dropped > 1 foot § Drawdown ROI/Vacuum ROI – Up to 45 Lateral Feet
7-Day Pilot Test - Results Vapor Inlet Concentration (ppmv) Vs. Time § Stinger Depth 16,000 § Well Combinations Saturated Zone Exposed Saturated Zone Exposed Well Change/ Stinger Depth 14,000 § Dilution Change § Saturated Depths – 12,000 Dilution Vapor Inlet Concentration (ppmv) SVE 10,000 § LNAPL Mobilized Saturated Zone Exposed 8,000 § Increasing Vapor Final Stinger Depth - ~33.5-38.5 ft Well Change/ Concentrations – 6,000 Stinger Depth ? Change Saturated Zone 4,000 Exposed Initial Stinger Depth - ~26.5-32.5 ft § LNAPL Remained in 2,000 Subsurface 0 12/4/16 18:00 12/5/16 12:00 12/6/16 6:00 12/7/16 0:00 12/7/16 18:00 12/8/16 12:00 12/9/16 6:00 12/10/16 0:00 12/10/16 18:00 12/11/16 12:00 12/12/16 6:00 12/13/16 0:00
High Vacuum Multi-Phase Extraction Event March 2018 – July 2018 (134 Days) § Measured LNAPL (Intermittent) § Prior to HVME: MW-2, MW-12, MW-15, MW-16, MW-26, RW-4 § Additional During HVME: MW-21, MW-22 § Nine extraction wells (different combos, 6 wells at a time) § MW-2, MW-12, MW-15, MW-16, MW-21, MW- 22, MW-26, RW-2, RW-5
High Vacuum Multi-Phase Extraction Event Considerations § Measured Depth to LNAPL § Beginning (6 wells): 31 – 33 feet § During (2 addtl wells): 38 – 41 feet § Total Depth of Wells with LNAPL § 35 – 46 feet § Stinger Placement § Bottom of LNAPL zone and/or bottom of well (pilot test data)
High Vacuum Multi-Phase Extraction Event – Results § System Parameters § Air Flow: 155 – 260 SCFM (Consistent 180 – 185 CFM) o Variable in beginning as saturated zone exposed o High when wells added § Vacuum: 15 – 22 Inches Hg (Consistent 21 – 22 Inches Hg) o Variable in beginning as saturated zone exposed o Low when wells added § Vapor Conc: 6,000 – 20,000 ppmv (No Dilution) o High as saturated zone exposed § Average of 17,689.7 Gallons (Equivalent) of Hydrocarbons Removed (131 GPD) § 555,020 Gallons of GW Removed (4,111 GPD) § Drawdown ROI/Vacuum ROI – Up to 55 Feet
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