Remedial Process Optimization - Moffett RAB


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Presentation to the Moffett Restoration Advisory Board January 8, 2009 by Peter Strauss, a consultant to

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Remedial Process Optimization - Moffett RAB

  1. 1. Peter Strauss PM Strauss & Associates Technical Advisor to community groups throughout the US Technical Advisor to Center for Public Environmental Oversight (CPEO) on the Moffett Field and MEW Technical Assistance Grants
  2. 2. Remedial Process Optimization • In June, EPA ordered that each of the MEW companies, the Navy and NASA to develop remedial process optimization (RPO) studies for each of the source areas and the regional system. • As I understand it, after EPA provides comments on the RPOs, the FFS will continue and the results of the RPO studies will be melded into it.
  3. 3. Need for RPO • The basic premise of RPO is a systematic evaluation and enhancement of remediation systems • Systems at MEW/Moffett were designed with knowledge and conditions at the time • New technology has developed • Old systems haven’t worked as well as anticipated • Extraction and monitoring wells were located in places that may not be ideal • Land use has changed.
  4. 4. Need for RPO (Lenny’s Chart) Est. M a s actual s r e rpo m o rpo v MCL a l time
  5. 5. Potential Benefits Examples from other sites • A well rehabilitation program was initiated to improve the well yields • A removal technique focusing on the source area may allow discontinuation of all site-related active remediation in less than six months (reducing remediation time by 9 years if pump and treat continued). • A Cost Effective Sampling process was developed that addressed the issue of sampling frequency. The above study examined where monitoring wells should be placed.
  6. 6. Concerns • RPO means different things to different people. • The RPO is a double edged sword: while it may accelerate and enhance remediation, responsible parties may see it as an opportunity to focus on what they can do less of (e.g., less extraction, less monitoring, abandonment of some extraction wells, opportunity to change remedial action objectives).
  7. 7. Remedial Process Optimization – Community Criteria The community believes that RPO should focus on: Accelerating cleanup Reducing plume migration Increasing the rate of mass removal Improving health and safety (e.g., reducing risk). Improving the long-term monitoring system Cost and efficiency should be evaluated, but should not be the primary decision criteria.
  8. 8. Optimization of Remediation System • Alternatives that replace current systems must speed up remediation, remove or destroy contaminants that are not being addressed by the current system, and/or increase mass removal rates. • Delineate an exit strategy • Consider natural resource use • Evaluate the effectiveness of existing institutional controls as well as the need to establish new institutional controls • Evaluate hot spot removal. • Evaluate changes in systems to simplify them
  9. 9. Well Location, Removal and Extraction Rates • If wells are being removed or extraction rates decreased, there should be a guarantee that capture zones will be maintained. • Evaluate the need for additional wells and/or increasing extraction rates. • Evaluate lateral dispersion/convection to identify preferential pathways. • Evaluate the need to refurbish or replace extraction and monitoring wells.
  10. 10. Long-Term Monitoring • Evaluate effectiveness of long term monitoring, as little attention is paid to this in the RI/FS process. • Evaluate less costly/more accurate approaches to long-term monitoring • If there are changes to the remediation system, the monitoring system should be adjusted accordingly so that it will monitor changes in performance. • Long-term monitoring should also be integrated into a contingency plan (e.g., failure of slurry walls).
  11. 11. Health and Safety • Ensure that the systems will be at a minimum as protective to environment, and health and safety, as systems already in place • The RPO process should not be used to change Remedial Action Objectives; although it may provide basis for doing so, RAOs should only be changed by ROD amendment, with appropriate public participation. • Assess changes in environmental conditions and land-use, and strategies should be developed that address these changes.
  12. 12. Examples of Recommendations • Evaluate the frequency of monitoring and the efficiency of the program • Discharge to the Palo Alto Regional Water Quality Control Plant (RWQCP) without pretreatment • Reduce extraction rate/close some wells • In conjunction with the optimization activities, the existing RAOs should be evaluated • No modifications to the treatment system components are necessary to optimize its operations
  13. 13. Technologies Considered • Pulsed Extraction • Treat subsurface prior to extraction and treatment of the groundwater, such as surfactant flushing • Treat VOCs in multiple matrices, e.g., dual-phase extraction • Permeable Reactive Barriers (including modifying existing slurry walls) • In-situ Bioremediation • In-situ Chemical Oxidation • Bioaugmentation • Phytoremediation • MNA (monitored natural attenuation)