J A N U A R Y 1 5, Vapor Intrusion in Utility Corridors: What We Know and What We Don t Know

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1 J A N U A R Y 1 5, Vapor Intrusion in Utility Corridors: What We Know and What We Don t Know

2 P R E S E N TAT I O N O V E R V I E W Background on Minnesota Department of Transportation (MnDOT) and correlation to utility corridors. Findings from MnDOT/Braun Intertec soil vapor policy evaluation. Description of potential vapor intrusion mitigation techniques for utility corridors.

3 M N D O T A N D U T I L I T I E S Minnesota has the 5 th largest highway system in the nation. 140,000 miles of roadway in Minnesota. Utilities generally run along each side of the roadway and often down the center resulting in over 400,000 miles of utility, with more utilities in areas of dense population. Various cities and counties also route utilities in public right of way and face many of the same issues as MnDOT with regards to utility corridors.

4 U T I L I T Y C O R R I D O R D O W N T O W N S T. P A U L

5 M A I N S T R E E T M N ( M N D O T T R U N K H I G H W AY ) Petroleum Bulk Storage Tastee Freeze Gas Station Bud s Auto Repair Dry Cleaners Town Hall

6 F A C T S A N D C H A L L E N G E S Utilities installed in MnDOT ROW serve a public good. This will not change. MnDOT, cities, and counties own utility corridors (ROW) but do not own contamination migrating to corridors. Who is responsible? 70% of utilities in MnDOT ROWs are owned and installed by private utility companies. Costs for deviations to standard specifications of private utilities that are not required by regulations (law, code, etc.) are likely be borne by MnDOT. Existing guidance for VI mitigation in utility corridors is general and focused on contaminated sites.

7 S O I L V A P O R P O L I C Y E V A L U A T I O N Researched available regulatory guidance regarding soil vapor intrusion. (MPCA, MDH, MnOSHA, EPA, ITRC, California EPA, Arizona DEQ, New Jersey DEP/DEC, New York DoH, Pennsylvania DEP, South Dakota DENR, Washington DE, Wisconsin DNR). Contacted DOTs of other states to identify best practices for vapor mitigation specific to utility corridors. (Arizona DOT, CalTrans, Iowa DOT, New Jersey DOT, New York DOT, North Caroline DOT, Pennsylvania DOT, Virginia DOT, Wisconsin DOT) Outlined common vapor mitigation techniques.

8 K E Y M P C A V A P O R I N T R U S I O N D O C U M E N T S Petroleum Remediation Program: Potential Receptor Surveys and Risk Evaluation Procedures at Petroleum Release Sites, Petroleum Remediation Program, Guidance Document 4-02, c-prp4-02, September Vapor Intrusion Assessments Performed During Site Investigations, Petroleum Remediation Program Guidance Document 4-01a, C-prp4-01a, October Petroleum Brownfields Program Response Action Plans, Petroleum Remediation Program, Guidance Document 5-03, January Clean-up/Super Fund/VIC: Background Information on the Intrusion Screening Values, Cleanup/Superfund #4.08, c-s4-08, September Risk-Based Guidance for the Vapor Intrusion Pathway, Superfund RCRA and Voluntary Cleanup Section, c-s4-06, September Brownfield Program Response Action Plans, Petroleum Brownfields and Voluntary Investigation and Cleanup Programs, c-rem4-43, July General Guidance: Vapor Intrusion Technical Support Document, c-rem3-01, August 2010.

9 M P C A G U I D A N C E F O R U T I L I T Y C O R R I D O R S Source: Brownfield Program Response Action Plans Petroleum Brownfield and Voluntary Investigation and Clean Up Program, Minnesota Pollution Control Agency, C-rem-4-43, July 2013.

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11 V I G U I D A N C E F R O M O T H E R S TAT E S VI guidance varies from state to state. Most guidance related to VI is focused on potential threats to buildings. Most guidance related to VI and utility corridors focuses on assessment protocols. Wisconsin has a detailed document that is often referenced by other states(1). No significant guidance related to mitigating VI along utility corridors. (1) Guidance for Documenting the Investigation of Utility Corridors, Wisconsin DNR, RR-649, October 2013.

12 B E S T P R A C T I C E S O T H E R D O T S We re-route utilities, if feasible, or use different materials depending on contaminants. We sometimes use flowable grout to prevent migration along the utility corridor. We reach out to the state environmental agency for advice. We do not have any policies or guidance documents related to VI. We rely on private utility companies to follow their own protocols. VI is not impactful enough to warrant a designated program.

13 M I T I G A T I O N T E C H N I Q U E S Reroute utility corridors, if possible Careful backfill material selection Flowable mortar, clay plugs or other physical barriers Vapor barrier around trench Utilize horizontal drilling Use piping materials resistant to the impacts* Use chemical resistant gaskets* Wrap the pipe with plastic* *These approaches may protect the utility, but may not prevent vapor migration along the utility.

14 B O T T O M L I N E Utility corridors can act as preferential migration pathways from past releases or future releases. There is abundant guidance for preventing vapor migration into buildings and assessment protocols. There is very little guidance related to mitigation of vapor migration along utility corridors. VI mitigation increases $$ in many cases and may not always be effective. VI mitigation poses maintenance challenges. Who s responsible for risk in public right-of-ways (PRPs, MnDOT, counties, cities)?

15 Questions? Brian Kamnikar, P.E Jackie Dylla Michael Beck, P.E