ESM 223-61ESM 223Risk-based Clean-up CriteriaESM 223-62Clean-up Criteria] Objectives:]]]]ESM 223-63How clean is clean?] Cleanup goals should be established for each media (water, soil, air) at levels which adequately protect human health and the environment] Some environments (e.g. wetlands) may be much more sensitive than the levels established for human health, and may need a separate risk assessment to determine cleanup goalsESM 223-64Cleanup Objectives] Factors to consider:]]]]]]]ESM 223-65Cleanup Objectives] Factors to consider:]]]]]ESM 223-66Cleanup Objectives] Action Levels (AL) are established for each media, and are different for carcinogens than for non-carcinogens] PRGs (Preliminary Remediation Goals)] Which pollutant?]]ESM 223-67Cleanup Objectives] Calculation of Media-specific Action Levels for Carcinogens:AL =R BW LT CFSF I ABS EDR = risk level (usually 10-6)=[mg/kg]or [mg/L]CF = conversion factor (106for soil, 1 for water)I = intake assumption (mg/day for soilingestion; L/day for water ingestion)ESM 223-68Cleanup Objectives] Example: Soil contaminated with methylene chloride, with children potentially nearby] 200 mg soil/day ingestion] SF = 7.5 x 10-3mg/kg day] BW = 16 kg] ED = 5 years] LT = 70 yearsAL = target Cs=ESM 223-69Cleanup Objectives] Example: CH3Cl in surface water] Ingestion of water: 2 L/day] BW = 70 kg] LT = 70 years] BCF = 0.91 L/kg] FIR = 6.5 g/dayAL = target Cw=ESM 223-610Cleanup Objectives] Calculation of Media-specific Action Levels for Non-Carcinogens:AL =RfD BW CFI ABS=[mg/kg]or [mg/L]Example: Soil contaminated with EthylbenzeneAL = target Cs=ESM 223-611Cleanup Objectives] Parameters to consider when calculating exposure levels are:]]]]ESM 223-612Cleanup Objectives] Case Study: Cleanup Standards for Petroleum Hydrocarbons] Many states use Total Petroleum Hydrocarbon (TPH) as a regulatory basis for setting cleanup standards for petroleum contaminated sites, such as gasoline stations and refineries] TPH represents the total concentration of many hydrocarbons and other constituents of gasoline, diesel and jet fuelESM 223-613Cleanup Objectives] Samples taken and analyzed are characterized as TPH-gasoline or TPH-diesel based on the range of hydrocarbons detected in the analysis] Regulations are usually based on a single numerical standard, which is supposed to cover the risk from all the potential constituents of gasoline, diesel or jet fuel] It is efficient to have just one standard for each typeESM 223-614Cleanup Objectives] Problems:]]ESM 223-615Cleanup Objectives] Problems:]]ESM 223-616Cleanup Objectives] Problems]]ESM 223-617Cleanup Objectives] The most common cleanup standard for TPH cleanup is 100 mg/kg (although the range across various states is from background to 10,000 mg/kg soil)] Standard varies among states depending on the type of TPH (diesel or gasoline) and factors such as depth to groundwater, proximity of human populations and future use of the siteESM 223-618Cleanup Objectives] The basis for the 100 mg TPH/kg soil standard is the protection of taste and odor qualities of groundwater, which are set at 1 mg/L] The soil cleanup target was set at 100 times the groundwater standardESM 223-619Cleanup ObjectivesWashington State Soil Cleanup StandardsBenzeneTolueneEthylbenzeneXyleneTPH-gasolineTPH-diesel0.5 - 2.5 mg/kg40 - 130 mg/kg20 - 250 mg/kg20 - 250 mg/kg100-600 mg/kg200-800 mg/kgESM 223-620Cleanup Objectives] EPA Methods 8020, 8240 and 8270 specify the use of GC/MS to identify the organic components and determine their concentrations, in particular for PAHs, BTEX and MTBE] A complete analysis of the samples can provide a “fingerprint”]]]ESM 223-621Cleanup Objectives] There are two possible routes:] Determine chemical-specific action levels for individual toxic components] Apply toxicity factors for specific petroleum products (i.e. gasoline, diesel, jet fuel, etc.)ESM 223-622Cleanup Objectives] ISSUES:]]]ESM 223-623Cleanup Objectives] Use of a lumped RfD or SF does not consider the mobility (higher solubility and volatility) of the more toxic BTEX compounds, or the sorption characteristics of PAHs, which are more likely to be ingested along with soil particles] Recommendation: do a complete analysis and use individual, chemical specific risk assessment to evaluate the real risksESM 223-624Cleanup Objectives] Oil Spill at Sea?] Types of compounds?]]] Pathways?]]] Receptors?]] Major risks?]]ESM 223-625Cleanup Objectives] Ecological Risk Assessment] Washington State has pioneered the use of bioassays to determine the toxicity of sediments and soils affecting natural environments] Use two acute and one chronic biological test to evaluate marine toxicity] Amphipod mortality bioassay] Larval mortality and abnormality bioassay] Bioassay to observe reduced biomassESM 223-626Example: Soil Cleanup Guidelines] USEPA Soil Screening GuidanceESM 223-627Example: Soil Cleanup GuidelinesESM 223-628Example: Soil Cleanup GuidelinesESM 223-630Example: Soil Cleanup GuidelinesESM 223-631Example: Soil Cleanup GuidelinesESM 223-633Example: Soil Cleanup GuidelinesESM 223-634Example: Soil Cleanup GuidelinesESM 223-635Example: Soil Cleanup GuidelinesESM 223-638Example: Soil Cleanup GuidelinesESM 223-639Example: Soil Cleanup GuidelinesESM 223-640Example: Soil Cleanup GuidelinesESM 223-641Example: Soil Cleanup GuidelinesESM 223-642Example: Soil Cleanup GuidelinesESM 223-643Example: Soil Cleanup GuidelinesESM 223-645Example: Soil Cleanup GuidelinesESM 223-646Summary] Screening or Clean up Levels are:] Inverse calculation of risk] Must make a decision on acceptable risk level] Mixtures:] Chemical specific] Risk factor for mixture (if composition is known)]