IRON AND MANGANESE IN GROUNDWATER IMPLICATIONS, OPTIONS AND RECOMMENDATIONS FOR REGULATING CONTAMINATED SITES IN BC

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1 IRON AND MANGANESE IN GROUNDWATER IMPLICATIONS, OPTIONS AND RECOMMENDATIONS FOR REGULATING CONTAMINATED SITES IN BC Ian Mitchell, SLR Consulting (Canada) Ltd.

2 Acknowledgements Greg Sutherland (CSAP, O Connor) Peggy Evans (BCMOE) Robin Jones (CSAP, SLR) Raminder Grewal (UDI, CSAP, Keystone) Paul Gordon (CPPI, Suncor) Phil De Leeuw (BCBC, Imperial Oil) Ian Mitchell (CSAP, SLR)

3 Background BCMOE released 2 key technical guidance documents in 2011 (TG6 and TG8) Has resulted in DW applying at most sites Has increased uncertainty and delays with significant economic impacts In June 2011, BCMOE engaged CSAP to hold a stakeholder workshop to identify key issues and form committees to evaluate options

4 Background A key issue identified is that TG6/TG8 require Fe & Mn analysis if organic contamination is present Many sites found to exceed for Fe and Mn resulting in substantial complications A TG6 working group was formed to review Fe and Mn issues and to develop timely options for BCMOE consideration

5 Issues Increased cost, uncertainty associated with delineation, risk assessment Recent increase in Mn and Fe DW standards from aesthetic-based values to toxicity-based values has provided little relief Difficulty in determining background concentrations in urban/industrial areas Background concentrations highly variable Off-site notification issues Return of sites to productive use delayed

6 BCMOE Perspective Options must be practical and apply Province-wide Want to avoid orphan liability If an option leaves contamination in place, who will pay for alternate groundwater resource? If Fe & Mn are the drivers, will TG6 work for other contaminants?

7 Work Group Objectives Review the basis for BCMOE guidance Document the economic impacts of the current Fe and Mn DW standards Conduct a technical literature search to characterize Fe and Mn plumes associated with PHCs: How far they typically extend past PHC plumes How long they persist after PHC remediation

8 Work Group Objectives Research what has been done in other jurisdictions and on what basis Review Fe & Mn data from site assessments to identify where and how often Fe and Mn background concentrations exceed DW Review cost and practicality of Fe and Mn DW treatment technologies Define potential solutions and approaches in consultation with BCMOE

9 Economic Impacts Presence of Fe & Mn estimated to increase delineation costs by $25k - 100k per site Has affected more than 500 sites in BC Estimated that over $100M in site redevelopment has been deterred in BC After PHC remediated, lingering Fe & Mn has resulted in many sites remaining vacant Discourages use of regulatory closure Uncertainty has deterred potential purchasers Refinancing not approved

10 Technical Background Dissolved Fe and Mn are generated by reducing conditions that develop under anaerobic biodegradation of PHCs Consultation with natural attenuation experts in Canada and the US indicated that the Bemidji site in Minnesota provides some of the most comprehensive information available on Fe and Mn associated with PHC plumes

11 Literature Review Figure from US Geological Survey, Fact Sheet

12 Literature Review PHC Plume Fe, Mn Plume Research has shown that the extent of dissolved Fe and Mn is closely tied to the leading edge of the PHC plume

13 Literature Review PHC Plume Fe, Mn Plume At leading edge of PHC plume, transitions from anaerobic back to aerobic conditions; causes Fe & Mn to precipitate out and more rapidly degrades residual PHCs

14 Literature Review PHC Plume Fe, Mn Plume US studies of >1,000 sites indicate that most PHC plumes extend <75 m; suggests that Fe & Mn plumes associated with PHC s may be similarly limited in extent

15 Literature Review Journal of Contaminant Hydrogeology 53 (2001)

16 Literature Review How long does Fe and Mn linger? PHC Plume Fe, Mn Plume Lack of information in the literature on Fe and Mn persistence after PHC remediation Hydrogeology and geochemistry key factors

17 Literature Review Experience of working group participants that when the PHC source area is removed in coarse grained soils, dissolved Fe and Mn concentrations often recover relatively quickly to background levels (~2 years?)

18 Other Jurisdictions Working group researched how other regulatory jurisdictions have dealt with Fe & Mn, and precedents that have been set Many jurisdictions do not require Fe/Mn analysis during contaminated sites investigations for the protection of DW: Ontario - USEPA Washington - Denmark Oregon

19 Other Jurisdictions

20 Background Issues Fe and Mn occur above DW standards in many shallow aquifers due to natural or wide range of anthropogenic sources Makes delineation challenging Difficulty in determining source area(s) Fe and Mn behave differently in different groundwater systems BCMOE database for groundwater is primarily from deep water supply aquifers

21 Background Issues Working group reviewed Mn data from site investigation background wells across BC The average Mn concentration was found to exceed the DW standard in Vancouver (dataset 103 wells) Mn found to exceed the DW standard in 45 municipalities across BC (more than 350 wells)

22 DW Treatment Technology There are common, commercially-available and economically-feasible treatment options for homeowners to remove Fe and Mn from drinking water Treatment typically involves oxidation/filtration; system costs ~$1K for single family dwelling Fe and Mn are routinely tested for DW supply Several Municipal water supply systems currently must treat for Fe and Mn

23 Working Group Conclusions Substantial economic impacts associated with regulating Fe/Mn for DW supply Background concentrations of Fe and Mn found to exceed DW standards at many sites in BC The extent of Fe/Mn is correlated to PHC plumes and is constrained by associated redox conditions

24 Working Group Conclusions Fe and Mn treatment is common, economical and readily available Fe and Mn treatment is commonly implemented for aesthetic issues; aesthetic standards are 10x less than tox-based standards There are precedents for not regulating Fe and Mn during contaminated sites investigations

25 Options Presented to BCMOE Several options considered by the working group: Develop specific exemptions for Fe and Mn Simplify the protocols for obtaining a background release Develop regional background concentrations for Fe and Mn for each region in BC Remove Fe and Mn DW standards from the regulation

26 Working Group met with BC MOE on April 2, 2012 for further discussion and input on options refined by BC MOE

27 BC MOE Revised Options Repeal Fe/Mn standards Revise Fe/Mn standards Adjust Fe/Mn standards for Provincial background levels Limit Fe/Mn standards to sites where DW is being used (rely on treatment for future use) Limit delineation for Fe/Mn redox sites Limit applicability of Fe/Mn standards to sites with specific uses

28 Next Steps BC MOE developed a criteria decision matrix All potential options were run through the decision matrix Mandatory Criteria Failure of a single criterion = exclusion of option Desirable Criteria

29 Next Steps Repeal of Fe/Mn standards no longer considered Proposed solution expected within ~ 6 months Solution likely tied to exemptions for specific Fe/Mn sources, with a monitoring commitment

30 Thank You SLR Consulting (Canada) Ltd. Questions?