PILOT TESTING AND FULL-SCALE ISCO REMEDY DESIGN FOR DEEP
BEDROCK AQUIFER
Second Annual RE3 Conference January 27-29, 2014, Philadelphia, PA
Presented By:
Omer Uppal, Brian Blum, C.P.G., LSRP, Erica Sterzinar, and Annie Lee
PRESENTATION OUTLINE
• Site Background • Remedial Approach • Phase I Pilot Test
• Injection Implementation • Testing Results
• Phase II Pilot Test • Hydraulic Fracturing • Injection Implementation
• Testing Results Synopsis • Conclusions
• Proposed Full-Scale ISCO Remedy Design
SITE BACKGROUND
• 98 Acre Former Industrial R&D Facility
• Trichloroethene (TCE) impacts in soil and groundwater
• Groundwater concentrations of TCE up to 59,000 ppb (PIW-1B, Nov 2011)
• Bulk of TCE impacts in the intermediate bedrock zone
• 155 tons of source area soil removed in 2006
Extent of TCE Plume (1 ppb)
Groundwater
Flow Direction
• Unstratified Glacial Deposits
• Bedrock (Diorite)
SITE GEOLOGY
Photographer: Siim Sepp, 2005, Source: Wikipedia
Diorite fragments from well drilling
REMEDIAL APPROACH Why Potassium Permanganate? • Bedrock expected to have low SOD
(0.1-0.65 g/kg), enabling chemical oxidation to be more cost effective
• Known to be effective for removal of chlorinated ethenes
• Relatively short remedial timeframe • MnO4
- Relatively long subsurface half-life (months to years)
2KMnO4 + C2HCl3 2CO2 + 2MnO2 + 3Cl- + H+ + 2K+
Permanganate MnO4
- + 4H+ + 3e- → MnO2(s) + 2H2O E° = 1.70 V
PHASE I ISCO PILOT TEST – NOVEMBER 2011
3 Injection Wells:
• Shallow bedrock
• Intermediate bedrock
• deep bedrock
FIELD IMPLEMENTATION
Automated Portable Bulk Feed System (Vironex)
INJECTION VOLUMES
* 97% of solution injected into the deep bedrock zone
INJECTION SUMMARY
• 6,081 gallons of 2.5% potassium permanganate
• 1,260 lbs of oxidant
• Three day operation
INJECTION OBSERVATIONS
• Shallow and Intermediate Bedrock: No measureable flow at injection pressures up to 100 psi
• Deep Bedrock: Able to inject at flow rates ranging from 5 to 22 gpm at a pressure up to 60 psi
RADIUS OF INFLUENCE Color (Permanganate = Purple)
• Observed pink water at MW-12C
Groundwater Mounding
• Observed groundwater mounding at MW-12C, MW-16B, MW-17B and MW-12D.
*Radius of influence for the deep zone is at least 25 feet
PHASE I TESTING RESULTS
Analytical Results:
• 99% reduction in TCE at PIW-1C, where the majority of the solution was injected
• 62% reduction in TCE at MW-12C, the directly downgradient deep monitoring well
PHASE I TESTING RESULTS
Geochemical Parameters: ORP
pH
PHASE I TESTING RESULTS
• ISCO is a feasible remedial technology for the site.
• Concentrations did not decrease significantly due to the inability to inject in the intermediate bedrock zone.
• Hydraulic fracturing needed to achieve reasonable injection rates in the intermediate bedrock zone (Phase II)
PHASE II ISCO PILOT TEST – MAY 2012 Objectives:
• Obtain injection flow-pressure relationships for full-scale remedial design
• Evaluate strategies to increase chemical distribution
• Evaluate effectiveness of hydraulic fracturing to facilitate injection in the intermediate bedrock zone
FIELD IMPLEMENTATION Methodology and Operation:
• Installed an additional intermediate injection well (PIW-2B)
• Hydro-fractured PIW-2B
• Injected 2,000 gallons of 2.5% KMnO4 (452 lbs) in PIW-2B
HYDRAULIC FRACTURING
• Fracturing of rock by a pressurized liquid
• Increases connectivity of aquifer and well yield
• Performed at PIW-2B at 100-150 bgs, where highest TCE concentrations observed, by Northeast Water Production, Inc.
• Direct hydraulic connection was observed, as a function of water level fluctuations, between PIW-2B and PIW-1C following hydro-fracturing.
OVERBURDEN OVERBURDEN
WEATHERED BEDROCK WEATHERED BEDROCK
DIORITE DIORITE
INJECTION OBSERVATIONS • Hydraulic fracturing can achieve flow rates of up to 15
gpm at pressures less than 50 psi.
• Hydraulic influence was observed at distances up to 125 feet during injection.
• Groundwater daylighting was observed at PIW-1C.
Visual evidence of permanganate solution in PIW-1A
PHASE II TESTING RESULTS • Oxidant distribution
at distances up to 125 feet downgradient
• Oxidant was present at several wells during the post injection sampling round
• No indication of rebound at PIW-1B
Notes:
‒ -- = Sample not collected
‒ Sampled via passive diffusion bag (PDB) samplers
‒ NJDEP GWQS for TCE = 1 ppb
PHASE II TESTING RESULTS
• ISCO is feasible for the intermediate bedrock zone.
• Hydro-fracturing can significantly enhance oxidant injection rates and distribution in the subsurface.
• A larger scale injection well network will be more effective in distributing oxidant and reducing TCE concentrations.
FULL-SCALE ISCO REMEDY DESIGN
Remedial Strategy:
• Installation of six additional intermediate bedrock zone injection wells, one extraction well
• Hydraulic fracturing of select injection wells
• ISCO with NaMnO4 • Groundwater extraction at select wells along the
downgradient site boundary while injecting oxidant “Push-Pull ISCO Approach”
PUMP/WELL YIELD TESTING
Performed in April 2013 at seven monitoring wells to verify achievable extraction rates that can be sustained during ISCO injection. Tests Performed:
1. Specific capacity (step-drawdown) aquifer pumping tests
• Flow rates at individual wells ranged from 0.15 to 1.5 gpm
2. Constant-rate aquifer pumping test
• Conducted at seven wells simultaneously at 5 gpm (combined pumping flow rate)
PUMP/WELL YIELD TESTING RESULTS
• Total mass of 40% NaMnO4 = 61,100 lbs
• Target NaMnO4 injection solution concentration = 7.5% to 10%
• Total injection volume = 27,400 to 37,200 gallons
• Design injection rate = 10 gpm (over 6 hours/day)
• Design extraction rate = 3 gpm (over 8 hours/day)
Implementation Planned for Summer 2014
FULL-SCALE ISCO DESIGN
FULL-SCALE ISCO DESIGN
ISCO EQUIPMENT AND MANIFOLD LAYOUT
Source: Google Maps
QUESTIONS?