## Overview **of Remedial Approaches at Superfund Fractured Bedrock Sites** 

Edward Gilbert, CPG Technology Assessment Branch Technology Innovation and Field Services Division Office of Superfund Remediation & Technology Innovation1



## Remedial Technologies • Groundwater extraction and treatment (P&T) • In situ Chemical Oxidation (ISCO) / Reduction (ISCR) • Enhanced In Situ Bioremediation – Biostimulation – Bioaugmentation • In Situ Thermal – Electrical Resistance Heating (ERH) – Thermal Conductive Heating (TCH) – Gas Thermal Remediation (GTR) – Steam Enhanced Extraction (SEE) – Radio Frequency Heating (RF) • Monitored Natural Attenuation (MNA) January 14, 2014 12



## Contaminants of Concern • VOCs • SVOCs/PAHs • Metals • Pesticides/PCBs • Dioxins/Dibenzofurans • Radionuclides January 14, 2014 23 

## Frac Rock Site Decision Documents • Data mining of CERCLIS – FY2000 – 2012 (partial) RODs, ESDs, or Amended RODs – Queried text for any mention of fractured bedrock 

### • Groundwater Remedies

• 76 Sites • 87 Operable Units in fractured bedrock 

### • DNAPL Remedies • 7 Sites • 7 Operable Units in fractured bedrock January 14, 2014 34 

## Groundwater at Fractured Bedrock Sites • Selected Remedies at 87 OUs – 30 GW Extraction (including multiphase extraction) – 16 Bioremediation – 13 Oxidation (ISCO) – 3 Reactive Walls – 2 Chemical Reduction (ISCR)

– 36 No Action; deed restrictions; groundwater use/well drilling regulation; zoning regulation; covenants; monitoring; natural attenuation; MNA; etc. January 14, 2014 45 

## NAPL at Fractured Bedrock Sites • Selected Remedies at 7 Sites – 5 Free Product Recovery – 1 Bioremediation (oxygen addition) – 2 ISCO – 1 Vapor Extraction – 1 ERH – 1 Non-fundamental change (ESD) January 14, 2014 56



### CLU **- IN’s**  **Fractured Bedrock Project Profiles** http://clu-in.org/products/fracrock/ 

## • 248 profiles submitted – 114 GW Pump and Treat • Plus 13 Multi Phase Extraction 

### – 67 Bioremediation – 55 Chemical Oxidation (in situ) – 25 ‘Soil’ Vapor Extraction – 9 Thermal Treatment (in situ) – 5 Flushing (in situ) January 14, 2014 67 

## CERCLIS

January 14, 2014 7 

## CLU - IN8



## Region 2 Sites • 31 Sites with contaminated gw in fractured rock – 21 ROD – 10 Pre- ROD 

## • Selected remedies at 19 sites – 9 P&T (+ 1 possible) – 4 Enhanced bio (+ 1 possible) – 2 ISCO (+ 1 possible) – 3 MNA – 1 Leachate collection for containment – 4 TI Waivers January 14, 2014 89 

## Karst • Very difficult to characterize adequately – Conduits – Very high and turbulent groundwater flow velocities – Extreme heterogeneity – Dual-porosity and dual-permeability regimes – Sediment transport 

### • RODs for 71 sites – 53% no active groundwater remedy – 37% pump and treat – 21% some form of in-situ remediation technology January 14, 2014 910



## Remedial Effectiveness? • Jury is still out... – Shift from P&T to other technologies 

## • A method to track remedy progress/success? • Need for fractured bedrock site database – CERCLIS – SEMS – Clu- In January 14, 2014 1011 

## Technical Impracticability Waivers* • 91 waivers at 85 sites; FY88- FY11 • 85 waivers applied to groundwater – Complex geology cited as a contributing factor in the rationale for 54 of the 85 waivers • Fractured bedrock • Karst • Heterogeneous soils with low permeability 

### – VOCs, metals, SVOCs and PAHs January 14, 2014 11 * Summary of Technical Impracticability Waivers at National Priorities List Sites, EPA 201212 

## Technical Impracticability Waivers* • In light of the continuing scientific advances in groundwater remediation technologies which continue to evolve, regions should not be limited by previously-approved TI waivers described in this technical report as justification for what may be appropriate when evaluating and documenting current or future TI waivers. January 14, 2014 12 * Summary of Technical Impracticability Waivers at National Priorities List Sites, EPA 201213



## Future? • In Situ Thermal • Enhanced In Situ Bioremediation* • ISCO/ISCR* • Combined remedies/treatment trains • Continued use of P&T for control/containment • MNA * Fracking - Increased distribution/delivery January 14, 2014 13