Presentation on theme: "Independent Technical Review Support Activity: Risk Assessment for the Evaluation of Direct and Multi-Pathway Impacts of Emissions from the Maine Energy."— Presentation transcript:
Independent Technical Review Support Activity: Risk Assessment for the Evaluation of Direct and Multi-Pathway Impacts of Emissions from the Maine Energy Recovery Company Facility Biddeford, ME Prepared by Cambridge Environmental, Inc. Presented by: Travis R. Kline, MEM TechLaw, Inc.
Background Maine Energy Recovery Company Environmental Code Office, City of Biddeford TechLaw –Toxicology and Risk Assessment Group (TARA) –USEPA and State Programs: Senior technical oversight Human health and ecological risk assessment –Risk assessment guidance development T. Kline, Chair, Expert External Peer Review Panel: –Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities (USEPA 1998, 1999, 2005) –Risk assessment training: USEPA’s Air Toxics Risk Assessment USEPA’s Combustion Risk Assessment USEPA’s Developing Permit Conditions for Open Burn/Open Detonation Units No Conflict of Interest
TechLaw Experience ETTP Oak Ridge (OB/OD Disposal Facility), Oak Ridge, TN. Crab Orchard National Wildlife Refuge Superfund Site, PCB Thermal Treatment Unit (TTU) Operable Unit, Carterville, IL. Knowles Atomic Power Laboratory, Windsor, CT. Kodak, Rochester, NY. Albemarle, Orangeburg, SC. Calgon Carbon, Catlettsburg, KY. Mallinckrodt, Raleigh, NC. Southeast Kansas Cumulative Effects Study Lone Star Industries, Cape Girardeau, MO Holnam, Clarksville, MO Lafarge/Systech, Fredonia, KS Kansas Army Ammunition Plant, Parsons, KS Aplus/Laidlaw, Coffeyville, KS Maine Yankee, Wiscasset, ME
TechLaw Review Process MERC: Municipal solid waste Refuse derived fuel Steam generated electricity Air emissions: Long- or short-term public health risks? Normal operating and process upset emissions Adult and child residents, recreational fishers, subsistence farm family (adult and child) Maximum off-site points of impact based on dispersion/deposition modeling Inhalation of volatiles and particulates, ingestion of soil, Saco River-derived drinking water, and locally- produced foods (vegetables, milk, beef and fish). Not a hazardous waste combustion facility HHRAP
TechLaw Review Timeline/Scope Risk Assessment Protocol, Nov. 2004 –Consistency with USEPA guidance –Appropriate levels of conservatism Draft Risk Assessment Report, Dec. 2005 –Verify air modeling –Adherence to the approved protocol –Confirm sensitivity analysis Revised Risk Assessment Report, April, 2006 –Methods approved, commence quantitative QC –Media-specific calculations, risk estimates, data consistency Response to Comments, June, 2006 –Clarification: Data inputs, data cross-referencing Final Risk Assessment Report, June 2006 –Verify corrections, additions
Process Upset Emissions Startups, shutdowns, air pollution control system or combustion control system malfunctions Short-lived – waste feed stopped (opacity, CO, SO 2, others) Based on maximum 1-hour COPC exposures Significantly overpredicts actual maximum short-term impacts: –Composite, worst-case conditions. Simultaneously assumes: Plant operating at maximum COPC emission rates Process or control system upset Atmospheric dispersion conditions maximum short-term impacts Effects on long-term average: –July 1, 2001 March 31, 2005, MERC = 90% operating time –3997.5 outage hrs –If max system upset factor (3.9 combustion control upset) applied to each occurrence = 310 hrs operation. –Baseline assumes 100% operation, equivalent emissions during outage (3997.5 hrs) >> max upset conditions (310 hrs) –Max 1hr HQ = 0.011
Conservatism vs. Uncertainty Inherent conservatism – Follows USEPA HHRAP Site-specific values similar to HHRAP defaults Use of high-end emissions: –[ maximum detected]s or [X+2s d ]s vs. [avg. measured]s (% incrs.) –Res. adult: 2.2E-06 vs. 1.4E-06 (cancer risk) (62%) –Res. child: 0.077 vs. 0.039 (nc hazard) (105%) –Farmer adult:5.4E-06vs. 3.3E-06 (cancer risk) (62%) –Farmer child:0.048vs. 0.025 (nc hazard) (96%) –Fisher adult:3.3E-06 vs. 2.0E-06 (cancer risk) (68%) –Fisher child: 0.22 vs. 0.13 (nc hazard) (71%) Treatment of COPCs < detection limits: –Nondetect results: Use of proxy values: ½ MDL, MDL –Greatest impact: Residential adult 30% increase in use of full MDL vs. ½ MDL -4% decrease when all ND’s @ ½ MDL Greatest impact still less than 1/6 th of target risk
Conservatism vs. Uncertainty Chromium speciation: Hexavalent chromium (inh. carcinogen) –1% = mean measured fraction in MERC ash samples –2% = value used in baseline estimates –10% = extreme upper-bound estimate (example) –Greatest potential impact on Adult farmer: 1% 3.49E-06 2% 3.55E-06 10% 4.03E-06 Deviation from HHRAP: Mercury speciation and distribution: –Baseline speciation and distribution based on MERC boiler (combustion) stack gases –Recreational fisher (adult) Avg. of measured values (baseline): HI = 0.15 HHRAP default distribution: HI = 0.13 Maximum measured HgCl2 vapor fraction: HI = 0.16
Superposition of maximum and concentrations and deposition values –Superposing the separate max impact locations for each source dispersion/deposition –Increase of less than 10% Bounding estimates for COPCs in the Saco River –Assume all COPCs emitted enter river –Overestimates associated risks by a factor of at least 9, still below 1.0E-05 (risk) and 1.0 (hazard). Fisher exposures: All fish consumed from highest impact waterbody (e.g., 20.3 oz/wk for 40 years) Farmer exposures: All veggies, meat, dairy assumed home- grown at maximum impact (deposition) location (e.g., 19.7 ozs beef/wk, 3.9 qrt milk/wk for 30 years) Less conservative: Use of a non-zero kse (COPC loss in soil by erosion) –HHRAP: kse = 0 –Reduces overall HI for Rec. Fisher from 0.21 (kse=0) to 0.17. Conservatism vs. Uncertainty
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