Evaluation of Environmental Hazards at Sites with Contaminated

Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater Roger Brewer, Ph. D Hawai‘i Department of Health Hazard Evaluation and Emergency Response (November 21, 2017) 1

HDOH 2017 Webinar Series Part 1: Systematic Planning and Site Investigation Design (TGM Section 3) Part 2: Decision Unit Designation (TGM Section 3) Part 3: Sampling Theory & DU Characterization (TGM Section 4) Part 4: Field Implementation of DU-MIS Methods (TGM Sections 5 & 8) Part 5: Laboratory Processing of MI Samples (TGM Section 4) Part 6: Environmental Hazard Evaluation (TGM Section 13). 2

Hawai′i DOH Guidance for the Investigation, Remediation and Management of Contaminated Properties 1. Testing Soil, Water and Air for Contamination: Technical Guidance Manual: http: //eha-web. doh. hawaii. gov/eha-cma/Org/HEER/ 2. Determining if There is a Problem: Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater: http: //eha-web. doh. hawaii. gov/eha-cma/Leaders/HEER/EALs Hawaii Edition: Environmental Action Levels (EALs) Tropical Pacific Edition: Environmental Screening Levels (ESLs) (excludes HDOH-specific standards, originally developed for use in CNMI & Guam) HEER Webinars: http: //eha-web. doh. hawaii. gov/eha-cma/Leaders/HEER/Webinar 3

There are three methods to gain knowledge: The first, reflection, is the noblest; The second, imitation, is the easiest; And the third, experience, is the bitterest. Confucius

Site Investigation Process Site Characterization Environmental Hazard Evaluation Advanced Evaluation of Targeted Hazards Response Action • Past use of unreliable, “discrete” sample data and excessively conservative action/screening levels added years to project completion; • Use of Systematic Planning and DU-MIS investigation methods ensures resulting data useful for final decision making; • Significantly expedites site characterization, remediation and closure.

DU-MIS WEBINARS #1 & #2: SYSTEMATIC PLANNING AND DECISION UNIT DESIGNATION (TGM SECTION 3) SURFACE EXPOSURE DU SOIL TRENCH WORKER DU SOIL 6

DU-MIS WEBINARS #3 & #5: DU CHARACTERIZATION & MULTI INCREMENT SAMPLING METHODS (TGM SECTION 4) Discrete Problems DU-MIS Solutions Brewer, R. , Peard, J. and M. Heskett (2017). A critical review of discrete soil sample reliability: • Part 1 – Field study results • Part 2—Implications Journal of Soil and Sediment Contamination. 7

Multi Increment Samples are not “Composites” Composited Discretes (saves $$$ but unreliable data) Composited MI Samples (a bad idea and not allowed) 8 8

DU-MIS WEBINAR #4: FIELD IMPLEMENTATION OF DUMIS INVESTIGATION METHODS (TGM SECTION 5) 9

Webinar Outline • Environmental Hazard Evaluation (EHE): – – – Site characterization process; Overview of potential environmental hazards; Environmental Action/Screening Levels (EALs/ESLs); Comparison to USEPA RSLs and other screening levels; Initial identification of potential environmental hazards; Advanced evaluation of environmental hazards; • EHE Reports; • Environmental Hazard Management Plans (EHMPs); • Risk versus remediation.

Environmental Hazard Evaluation - Multiple Fields of Expertise Required • • Everyone: What are the DUs? Chemistry: What is it? Geology: Where is it? Physics: Where is it going? Toxicology: What can it do to me? Combined: What are the concerns? Attorneys: Who is going to pay? Directly incorporated into EHE guidance and EALs

Environmental Hazards Gross Contamination Human Health Terrestrial Habitats INDOOR AIR Vapor Intrusion Direct Exposure SOIL GAS Leaching Aquatic Habitats GROUNDWATER Gross Contamination Human Health Vapor Intrusion Drinking Water (toxicity)

Hawaii Groundwater Zones (Tier 1 Lookup Tables) Drinking Water Source Nondrinking Water Source Target SW= Acute SW= Chronic GW= DW A-1 A-2 GW= NDW B-1 B-2 “Tier 1” Soil EALs: • Contaminated soil at or near surface; • Over drinking water; • Unrestricted land use (e. g. residential).

EAL Sources Terrestrial Habitats (USEPA) Nuisance (MADEP) Human Health Vapor Intrusion (mod USEPA) Direct Exposure (site-specific) (USEPA RSLs) SOIL GAS Leaching: MADEP Aquatic Habitats (HI AWQC) INDOOR AIR GROUNDWATER Nuisance (Secondary MCL, MADEP) Human Health (mod USEPA) Vapor Intrusion (mod USEPA) Drinking Water (HI MCL)

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water Terrestrial Habitats - Gross Cont. 170 mg/kg For Example Only Check for Updates Aquatic Habitats 53 µg/L Human Health INDOOR AIR Vapors to IA 0. 098 mg/kg Direct Exposure 1. 1 mg/kg SOIL GAS Leaching: 0. 64 mg/kg 920 mg/m 3 GROUNDWATER Vapors to IA 190 µg/L Gross Cont. 170 µg/L Human Health Drinking Water 5 µg/L

Environmental Action Levels (EALs) • EALs for 150+ common contaminants; – Volume 1: Tier 1 Final EALs; – Volume 2: Technical background and detailed action levels. • Easy-to-use, Excel-based “EAL Surfer” electronic lookup tables (EAL Surfer Apps being developed): – Select site scenario; – Select chemical by name or CAS #; – Input site data; – Automatically identifies potential environmental hazards; – Summary report generated; • Complete investigation and screen out low-risk areas; • No significant hazards if concentrations <EALs; • Additional evaluation +/- remediation required if EALs exceeded.

Example: Former Fuel Tank Farm (TPH+BTEX) • TPH data assessed in same manner as individual compounds; • Toxicity factors and action levels for soil, water & air available for all potential concerns; • Often drives direct exposure risk over BTEX (see HEER webinars); • Groundwater metabolites assumed similar toxicity to parent hydrocarbons; • Remediation and/or long-term management often driven by gross contamination concerns (e. g. , short-term vapor emissions during construction, sheens, etc. ). Brewer, R. , Nagashima, J. , Kelley, M. and M. Rigby, 2013, Risk-Based Evaluation of Total Petroleum Hydrocarbons in Vapor Intrusion Studies: International Journal of Environmental Research and Public Health, Volume 10, pp 2441 -2467. http: //www. mdpi. com/1660 -4601/10/6/2441/18

Identification of Potential Environmental Concerns (e. g. , TPHg and BTEX) Gross Contamination (soil & gw) Vapor Intrusion (soil gas) Leaching (soil) Aquatic Toxicity (GW) Direct Exposure (soil) Hypothetical Site. For Example Only! • Identified Potential Environmental Concerns for TPH (including metabolites): • Gross Contamination: TPH soil and groundwater exceeds gross contamination screening levels (heavy contamination of soil, free product on groundwater); • Direct Exposure: TPH soil data (MIS/ISM) exceeds direct-exposure screening levels; • Vapor Intrusion: TPH soil vapor exceeds vapor intrusion screening levels; • Leaching Concerns: TPH soil data (MIS/ISM) exceeds leaching screening levels • Aquatic Toxicity: TPH groundwater data exceeds aquatic toxicity screening levels.

Site-Specific CSM and Considerations Exposure Pathways Complete? Vapors intruding buildings? Exposed soil? Leaching? Groundwater Impacted? Stream Discharges to aquatic habitats? ? Wells Impacted?

Partial Remediation and Long-Term Management -Environmental Hazard Management Plans (EHMPs)Gross Contamination (soil & gw) Vapor Intrusion (soil gas) Leaching (soil) Aquatic Toxicity (GW) Direct Exposure (soil) Hypothetical Site. For Example Only! • Example Remediation and Redevelopment Design: • Active remediation of Gross Contamination and highest-risk Vapor Intrusion and Direct Exposure risk areas; • Passive vapor barrier to future buildings as added measure of protection; • Monitoring of groundwater confirms dissolved-phase plume not migrating offsite above levels of potential concern; • Long-term management of soil & gw required for subsurface activities (EHMP).

Potential Environmental Hazards and Chemical Partitioning in the Environment vapors Sorbed NAPL Dissolved Vapor leachate Total Soil Conc. = Sorbed + Dissolved + Vapor + “Free Product” Primary Chemical-Specific Modeling Factors: Henry’s Law Constant (Vapor Conc. /Dissolved Conc. ); Sorption Coefficient (Sorbed Conc. /Dissolved Conc. ); Solubility. Assumed Soil Properties: moist soil, low organic carbon, etc.

Assumed Contaminant Partitioning in Soil (based on default USEPA RSL soil type) Sorbed Dissolved Vapor Eat Drink Breath Benzene Vinyl Chloride Ba. P • Chemical partitioning in soil directly tied to exposure pathway and risk; • Action levels reflect chemical fate and transport + toxicity.

Contaminant Group vs Primary Environmental Concern Leaching *Direct Exposure Chemical Family Light petroleum, solvents, pesticides, inorganic salts Carcinogen PAHs, PCBs, metals, etc. Vapor Emissions Carcinogenic VOCs Terrestrial Ecotoxicity Gross Contamination Noncarcinogenic metals & pesticides Heavy TPH, noncarcinogenic metals & solvents, phenols, etc. *Soil ingestion, inhalation of outdoor vapors and dermal contact

“Direct Exposure” Action Levels (water, soil, air, etc. ) (very simplified equations) 1. Risk = Average Daily Dose x Toxicity Factor 2. ADD = Media Concentration x Exposure Rate Default USEPA Exposure Rates: Inhalation: 10 -20 m 3/day Soil Ingestion: 100 -200 mg/day (<2 mm particles) Drinking Water: 1 -2 L/day 3. Media Action Level = Target Risk : Exposure Rate Toxicity Factor 4. Media Action Level = Target Max ADD : Exposure Rate

Direct Exposure Action Levels (Water, Soil, Air, etc. ) “Dose Makes The Poison” 1 Target, Risk-Based Average Daily Dose Chronic Health Effect Water A few gallons at once Acute Hyponatremia Aspirin 81 mg/day (3 drops/day) G/I tract 2 TPHg 0. 90 mg/day (1 drop/month) Multiple 2 PCBs 0. 0002 mg/day (1 mm grain/20 yrs) Multiple Chemical 1. For example only (safe dose varies with route of exposure, target cancer risk and noncancer hazard, child vs adult, etc. ). 2. Child (15 kg), chronic exposure over 6 years (noncancer HQ = 1. 0). Toxicity factors typically includes 10 -100+ fold safety factor. MTBE maximum daily dose = 28 µg/day Assumed water consumption = 2 L/day Drinking water action level = 14 µg/L

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water (10 -6 ECR) Human Health INDOOR AIR Direct Exposure 1. 1 mg/kg (10 -6 ECR) Alternative Soil & Air Commercial/Industrial DE Action Levels Also Provided SOIL GROUNDWATER For Example Only Check for Updates Human Health PCE MCL: Based on 10 -5 ECR Drinking Water 5 µg/L

Direct Exposure Soil Action Levels -Default Soil Ingestion Rate. Parameter Size Fraction Ingestion Rate (child) Ingestion Rate (adult) Current <2 mm particles 200 mg/day 100 mg/day Proposed <150µm particles 100 mg/day ? 50 mg/day ? • Some risk assessors recommend focusing on the <250µm or <150µm particles for incidental ingestion (flour-size particles on hands); • Testing of <250µm already required for bioaccessible arsenic, but assumes 100 -200 mg/day soil ingestion rate assumed; • Reducing the ingestion rate by a factor of two would double the soil direct exposure action levels (eating less soil so higher conc acceptable); • Concentration in fines, however, typically assumed to be double that of <2 mm fraction; • No net change in ultimate conclusion (action level doubled but reported soil concentration also doubled); • Assume current, total soil ingestion rate of 200 mg/day includes 100 mg/day <150µm particles and 100 mg/day 150µm to <2 mm particles.

Vapor Intrusion Action Levels (PCE example) (see separate webinars) Site Investigation Steps Residence Tropical “SSAF” =0. 0005 Indoor Air (0. 46 µg/m 3) USEPA VI Models Soil Gas + Field Data (920 µg/m 3) +/- Step 3: IA data Step 2: SV data Soil 0. 098 mg/kg Groundwater (190 µg/L) Step 1: Soil & G W data

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water Alternative C/I VI Action Levels Also Provided For Example Only Check for Updates Human Health INDOOR AIR Vapors to IA 0. 098 mg/kg Direct Exposure 1. 1 mg/kg SOIL GAS 920 mg/m 3 GROUNDWATER Human Health Vapors to IA 190 µg/L Drinking Water 5 µg/L

Step 3. Indoor Air Sampling (Caution!) • Indoor sources of VOCs (e. g. , petroleum & solvents); • Always include soil vapor data (tie to subsurface source? ); • “Large Volume Purge” subslab vapor data preferred (TGM Section 7; see HEER webinar webpage)

Hawaii Vapor Intrusion Action Levels Not Adequately Conservative for Colder Climate Zones VIR Region B 1 (Coastal) Moderate Risk (SSAF = 0. 002) VIR Region C (Mediterranean) Lower Risk (SSAF = 0. 008) VIR Region A (Cold, +Alaska) Highest Risk (SSAF 0. 003) VIR Region B 2 (Warm) Moderate Risk (SSAF = 0. 002) VIR Region D Tropical) Lowest Risk (SSAF = 0. 0005) Brewer, R. , Nagashima, J. , Rigby, M. , Schmidt, M. and O'Neill, H. (2014), Estimation of Generic Subslab Attenuation Factors for Vapor Intrusion Investigations. Groundwater Monitoring & Remediation, 34: 79– 92. http: //onlinelibrary. wiley. com/doi/10. 1111/gwmr. 12086/full

Frequency 2012 USEPA “Empirical” Database Attenuation Factors Invalidated (Brewer et al. 2014) • Vapor attenuation factors estimated for hundreds of homes; • Based on single, one-liter subslab vapor samples; 95% UCL SSAF= 0. 03 • Only valid if uniform vapor plume; • Vapor plumes heterogeneous; • Database can’t be “fixed” by statistical analysis; • Calculated attenuation factors 95% UCL reflects range of not “conservative, ” they are error in invalidated data technically invalid. Refer to HEER Vapor Intrusion Webinars: http: //eha-web. doh. hawaii. gov/eha-cma/Leaders/HEER/Webinar

Soil Leaching Action Levels 1. Concentration in soil Csoil = Cgw x [(6207 x H) + (0. 166 x Koc)] 2. Concentration in source leachate x x 3. Concentration in leachate at groundwater interface groundwater plume 4. Concentration in groundwater

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water Human Health INDOOR AIR Vapors to IA 0. 098 mg/kg Direct Exposure 1. 1 mg/kg For Example Only Check for Updates SOIL GAS Leaching: 0. 64 mg/kg 920 mg/m 3 GROUNDWATER Vapors to IA 190 µg/L Human Health Drinking Water 5 µg/L

Lab-Based Soil Leaching Tests Sorbed Dissolved Vapor leachate • SESOIL leaching model over predicts contaminant desorption and concentration in leachate; • Synthetic Precipitation Leaching Procedure (SPLP) batch more accurately estimates Kd and leaching hazards (see HDOH guidance and spreadsheet model); – 100 grams soil mixed in 2 liter water; – Kd based on original total mass vs mass dissolved; • Future: “LEAF” soil column leaching tests?

Groundwater-to-Surface Water Action Levels (protection of aquatic habitats) spring Aquatic toxicity action levels should be met at point of groundwater discharge (excluding mixing and dilution)

Groundwater Discharges to Surface Water Freshwater Springs Along Shoreline Aquatic toxicity action levels should be met at point of groundwater discharge (excluding mixing and dilution)

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water Terrestrial Habitats Human Health Aquatic Habitats C: 53 µg/L A: 1, 800µg/L Vapors to IA 0. 098 mg/kg Direct Exposure 1. 1 mg/kg (site specific) For Example Only Check for Updates INDOOR AIR SOIL GAS Leaching: 0. 64 mg/kg 920 mg/m 3 GROUNDWATER Vapors to IA 190 µg/L Human Health Drinking Water 5 µg/L

Gross Contamination Action Levels (function of short-term exposure risk, odor threshold, solubility, sheens and visible staining/contamination etc. ) • Short-term vapor emissions; • Explosive vapors; • Odors & nuisance; • Potentially mobile free product; • Staining or visible debris/contamination; • Interference with future development; • Include in site-specific EHMP if left in place.

PCE EALs 0. 46 µg/m 3 Residential, exposed soils, over drinking water Terrestrial Habitats Gross Cont. 170 mg/kg Human Health Aquatic Habitats 53 µg/L Vapors to IA 0. 098 mg/kg Direct Exposure 1. 1 mg/kg (site specific) For Example Only Check for Updates INDOOR AIR SOIL GAS Leaching: 0. 64 mg/kg 920 mg/m 3 GROUNDWATER Vapors to IA 190 µg/L Gross Cont. 170 µg/L Human Health Drinking Water 5 µg/L

EHE Report (separate or part of site investigation report) • Site Background • Summary of investigations • Comparison of site data to action levels • EHE: Identification of potential hazards • Advanced evaluation of targeted hazards • Conclusions & Recommendations • Summarize findings • Addition site investigation? • Advanced evaluation of targeted hazards? • Prepare remedial action plan? • Prepare EHMP? • No further action required?

Environmental Hazard Management Plans (long-term management of residual contamination) • Same information as in EHE • Appendix to closure report (simple) or separate document (complicated) • Include to-scale maps of affected areas • Summarize site restrictions & management needs • soil & groundwater management • caps, vapor barrier systems, etc. • land-use restrictions, etc. • Consider EHMP in budget for future development & maintenance: • Construction EHMP • Post-Construction EHMP (include upsdated EHE)

Risk versus Remediation USEPA 2017 (Removal Management Levels): “Where the cumulative carcinogenic site risk… is less than 10 -4 and the (cumulative) non-carcinogenic (index) is less than 1. 0, action generally is not warranted. ” *Ensure No Further Cumulative Remediation Investigation Risk Limits Measures Warranted Not Exceeded Warranted … Cancer Risk: 0 Noncancer Hazard: 0 Low Risk 10 -6 0. 2 10 -4 1. 0 ……. . High Risk *Other considerations include remediation feasibility, exposure scenario, target COPCs, confidence in toxicity factors, etc.

Remediation Measures Definitely Warranted USEPA 1991 (OSWER DIRECTIVE 9355. 0 -30): “For sites where the cumulative site risk to an individual based on reasonable maximum exposure… is below 10 -4 (i. e. , low excess cancer risk), action generally is not warranted. ” USEPA 1994 (National Contingency Plan): “In cases (which) result in a cumulative risk in excess of 10 -4 (i. e. , high excess cancer risk), (site-specific factors) may be considered when determining … (remedial actions and final) cleanup level(s). ”

Cumulative Risk vs Target EAL Risk Cumulative Risk = “Chemical A Risk” + “Chemical B Risk” + “Chemical C Risk” + “Chemical D Risk”. . . • • • Individual chemicals might not pose risk but in combination potentially significant risk present; Target risk for individual chemical typically set lower than maximum acceptable (i. e. , ECR 10 -4 and HQ 1. 0; Additional consideration of cumulative risk required if number of chemicals with similar health effects present exceeds number assumed in action level target risk (rare; see Appendix 1 Table J Target Health Effects).

Example PCE Target Risk Versus Selection of Soil Direct Exposure Action Level (residential) Soil Action Level 110 mg/kg selected as final action level 10 -5 10 -6 11 mg/kg 1. 1 mg/kg Noncancer Hazard Quotient Target Risk Range Excess Cancer Risk 10 -4 *Soil Action Level 1. 0 87 mg/kg 0. 2 17 mg/kg 0. 1 8. 7 mg/kg Considerations: Volatile chemical, inhalation risk, high confidence in cancer studies, often present with other carcinogenic VOCs.

Example Arsenic Target Risk Versus Selection of Soil Direct Exposure Action Level (residential) 10 -5 10 -6 4. 1 mg/kg 0. 41 mg/kg Noncancer Hazard Quotient *Soil Action Level selected as final action level Target Risk Range Soil Action Level 41 mg/kg Target Risk Range Excess Cancer Risk 10 -4 1. 0 23 mg/kg 0. 2 0. 1 4. 6 mg/kg 2. 3 mg/kg Considerations: Natural background, higher confidence in noncancer studies, primary risk driver if present, *bioaccessible arsenic.

Chemical-Specific Target Risks (App 1, Sect 4. 2. 2) Chemical Target Risk Rationale *Default (most VOCs) ECR = 10 -6 HQ = 0. 2 Conservative consideration of cumulative risk Ethylbenzene, Naphthalene, ECR = 10 -5 Heptachlor, Heptachlor Epoxide HQ = 0. 2 Higher confidence in noncancer toxicity factors PAHs ECR = 10 -5 HQ = 0. 2 Anthropogenic background, (Ba. P ECR = 5 x 10 -5, focus on nc) Chlordane, PCBs ECR = 10 -5 HQ = 1. 0 Focus on noncancer hazard, primary risk driver Aldrin, Dieldrin, ECR = 10 -4 HQ = 0. 5 Focus on noncancer hazard, cooccur, primary risk drivers Arsenic, TEQ Dioxins, Cr. VI ECR = 10 -4 HQ = 1. 0 Focus on nc hazard, primary risk drivers, nat background TPH HQ = 1. 0 Primary noncancer risk driver Lead separate model Reduced target blood level, anthropogenic background. *Tapwater default ECR = 10 -6 HQ = 1. 0 (see Appendix 1 for variances).

HDOH EALs versus Cal. EPA ESLs and USEPA RSLs GW Soil Environment Hazard 1 HDOH 2 Cal. EPA EALs ESLs USEPA RSLs Direct Exposure X X X Vapor Intrusion X X - Leaching X X - Gross Contamination X X - DW Toxicity X X X Vapor Intrusion X X - Aquatic Habitats X X - Gross Contamination X X - 1. HDOH: Vapor intrusion action levels reflect tropical climate. 2. Cal. EPA: Vapor intrusion screening levels reflect moderate climate with warm summers and short, cold winters.

HDOH EALs versus Cal. EPA ESLs and USEPA RSLs Risk Category Excess Cancer Risk Noncancer Hazard Quotient 1 HDOH 2 Cal. EPA 3 USEPA EALs 10 -4 to 10 -6 ESLs RSLs 10 -6 1. 0 0. 1 and 1. 0 0. 2 to 1. 0 1. HDOH: Chemical specific considerations made for both target cancer risk and noncancer hazard (default 10 -6 ECR and 0. 2 noncancer HQ; see App 1, Section 4. 2. 2). 2. Cal. EPA: Most conservative target cancer risk and least conservative target noncancer hazard applied to all chemicals (ignores potential cumulative risk). 3. USEPA: Most conservative target cancer risk for all chemicals. Two sets of noncancer action levels presented based on both most conservative and least conservative target noncancer hazard

Last Notes… • Don’t I need to compare the EALs to a 95% UCL? • Only if replicate MI samples RSD >50% (getting rare); • 95% UCL applied to discrete sample data in attempt to address distributional heterogeneity (aka “variability); • Field representativeness of single data set unknown; • Sampling theory for particulate matter not considered; • “Outlier” data inappropriately excluded; • Discrete sample data not allowed for final decision making; • Sampling theory used to address distributional heterogeneity under Multi Increment sampling methods; • Don’t I need to look for acute “hot spots” within DUs with discrete samples? Refer to recording of DU-MIS Webinar #3 (Sampling Theory) 53

How Do I Assess “Acute Risk”? 20’ x 20’ front yard Hypothetical Regulatory Requirement “No single discrete sample in upper 3” of soil shall exceed 400 mg/kg lead (short-term risk). ” Total Soil Mass = 3, 000 kg What soil mass does 400 mg/kg apply to? What is the Decision Unit? • 100 g? (discrete sample mass; 30, 000 potential DUs); • 1 gram? (standard laboratory subsample mass; 3, 000 potential DUs); • 200 mg? (default child soil ingestion rate; 15, 000 potential DUs); • 10 grams? (pica child soil ingestion rate; 300, 000 potential DUs); • Reality: • “Acute” soil screening levels not available for most contaminants; • Not feasible to negate presence of small masses of “acutely toxic” soil with any degree of confidence based on either discrete or MI soil sample data; • Scrape or cap site if realistic, exposure risk suspected (e. g. , lead paint chips); • Evaluate chronic risk with Multi Increment (MI) samples; 54 • Assume theoretical acute risk acceptable if long-term, chronic risk acceptable.

Summary • Environmental Hazard Evaluation (EHE): – Use of reasonably conservative, HDOH Environmental Action/Screening Levels (EALs/ESLs) expedites the risk assessment & remediation process; – Comprehensive action levels ensures that common, potential environmental hazards are not overlooked; – Cumulative risk and commonly accepted adjustments for target risks incorporated; – Advanced, site-specific evaluation for identified, potential hazards as necessary (rarely time/cost beneficial for Direct Exposure and Vapor Intrusion); • Results and recommendations summarized in EHE report; • EHMP prepared for remaining contamination (e. g. , construction, final closure, etc. ).

Questions? Discrete Sample Data + Excessively Conservative Screening Levels and “Site. Specific” Risk Assessments DU-MIS Data + Comprehensive, Reasonably Conservative EALs/ESLs and EHEs Faster, more reliable and cheaper in the long run 56