H&P Breakfast Seminar

Transcription

1 Vapor Intrusion Risk Pathway: Regulatory Updates H&P Breakfast Seminar September 25, 2012 Blayne Hartman

2 EPA Guidance Updates (Final Out in Nov 2012) EPA (OSWER & Superfund) - Anticipated Preference for sub-slab & indoor air 7 to 30 day indoor air sampling period Fixed Att factor of 0.1 for SG & for GW Sub-slab Att factor dropping to 0.01? Modeling no longer an exit No Public Comment on Draft!!

3 EPA Guidance Updates (Final Out in Nov 2012) EPA-OUST: Guidance for HCs Exclusion criteria? Yes Testing/Adoption of Biovapor model? In theory Frequently Asked Questions - done Summary of State Guidances - done No Public Comment on Draft!!

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5 ITRC PVI GUIDANCE 1. Introduction 2. Types of PVI Sites (Due out Fall 2012) 3. Conceptual Site Model 4. Basic Investigative Framework for PVI Sites 5. Site Screening and Prioritization 6. Investigative Toolbox

6 CA-DTSC CA Agencies New VI Guidance (10/2011) & Soil Gas Advisory (4/2012) EPA Region 9 Adopted Region 3 Screening Levels for TCE & PCE SF-RWQCB ESLs still not updated from June 2011 OEHHA Still using out-dated CHHSLs (pre RAGS Part F) San Diego DEH Soil gas sampling & analysis updated in SAM Manual SWQCB: Low Threat Closure Policy

7 DTSC VI Guidance Changes Preference for Sub-slab Samples for Cl-VOCs Collect Exterior SG Samples At Source Repeated Sampling of Soil Gas Raising Sub-slab AF to 0.05 (5x stricter) Can now measure permeability, diffusivity and radon for attenuation factor Changes in Toxicity of Some Compounds Defers to LUFT Manual for Petroleum HCs (p.38)

8 Residential (1e-6) New TCE Standard (As of October 2011) Indoor Air cancer: 0.43 ug/m3 (down from 1.2 ug/m3) Indoor Air non-cancer: 2.1 ug/m3 Groundwater: 1.1 ug/l Commercial/Industrial (1e-6) Indoor Air: 3.0 ug/m3 (down from 6.1 ug/m3) Indoor Air non-cancer: 8.8 ug/m3 Groundwater: 7.4 ug/l EPA R9 & DTSC Have Adopted OEHHA Has Not Adopted C/I

9 Residential (1e-6) New PCE Standard (As of March 2012) Indoor Air cancer: 9.4 ug/m3 (up from 0.41 ~22x!!) Indoor Air non-cancer: ~47 ug/m3 Industrial (1e-6) Indoor Air: ~47 ug/m3 (up 22x) Indoor Air non-cancer: 8.8 ug/m3 EPA R9 Has Adopted DTSC & OEHHA Have Not Adopted Either!

10 Soil Gas Allowed Levels PCE in Soil Gas, Residential Receptor RBSL (ug/m 3 ) DTSC Sub-slab 8.2 CHHSL 180 DTSC Step EPA R9 4,700 SAM Vapor Risk 5,500

11 DTSC Soil Gas Advisory Changes Sampling Purge volumes: include dry bentonite Equilibration times: 2 hours for tubes,? for probes Leak check specifications: report at VOC RL Analysis Methods 8021, 8260, TO-14, TO-15, TO-17 ok Naphthalene preferred by TO-17 Syringes & tedlar bags ok to use (in lieu of canisters)

12 Low Threat Closure Policy VI Scenarios LNAPL: 30 Dissolved: 5 or Dissolved with O2

13 Low-Threat Closure Policy Site Screens Out from VI Pathway if: If 30 of Biozone, NAPL screens out Vertically & horizontally If 10 of Biozone, benzene up to 1000 ug/l If 5 of Biozone, benzene up to 100 ug/l Bioattenuation zone: TPH-soil < 100 mg/kg Note: O 2 not Required

14 Low-Threat Closure Policy The Power of Oxygen If oxygen in soil gas >4%: Separation distance drops from 10 to 5 for benzene up to 1000 ug/l Soil gas SLs increase by 1000x! TPH-soil required for all scenarios but O2 not

15 Allowable Benzene in GW 1e-6 risk, Residential Scenario DTSC VI Guidance: ug/m3 / = 0.42 ug/l / 0.2 = 0.21 ug/l ~5000x lower than Low Threat Value of 1000 ug/l New EPA OSWER Guidance: 0.31 ug/m3/0.001 = 0.31 ug/l/0.2 = 1.5 ug/l ~3000 times lower than EPA-OUST Value!!

16 Soil Gas Allowed Levels Benzene in Soil Gas, Residential Receptor, 1-6 Risk RBSL (ug/m 3 ) DTSC Sub-slab 1.6 CHHSL 37 DTSC Step 5 42 CA Low-Risk Policy: O2<4% 85 SAM Vapor Risk 1,100 CA Low-Risk Policy: O2>4% 85,000 Ambient levels: 1 to 10 ug/m3

17 Low-Threat Policy: A VI Pathway Game Changer Active Service Stations Excluded Sampling Soil phase TPH needed from two depths O2 in soil gas Soil Gas Analysis Needed at all? Benzene, ethylbenzene & naphthalene only No longer worry about TPH?? VI Assessments Much Simpler & Less Expensive

18 Methods to Assess VI Indoor Air Sampling Groundwater Sampling Soil Phase Sampling Predictive Modeling Measure Flux Directly Soil Gas Sampling Supplemental Tools/Data

19 Ingredients for Effective VI Assessments Investigatory Approach Determine Correct Screening Levels Sample & Analyze Properly Know & Use Supplemental Tools Demonstrating Bioattenuation

20 The Most Important Ingredient Experience: Consultant Collector done soil gas before? Lab certified for methods? Regulator Public YOU! What level person is going in the field?

21 Most Common VI Bloopers Unit Confusion Assuming ug/l equivalent to ppbv Assuming ug/m3 equivalent to ppbv Screening Levels Comparing to generic screening levels Not calculating correct levels Sampling & Analysis Errors Program design: soil gas? GW? SS? IA? Using wrong hardware Using wrong analysis

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23 Don t Forget 8021/TO8021/TO-14 Can get to 1 ug/m3 for TCE, CCl4, PCE Can get to ~25 ug/m3 for Benz & Naphthalene 5 minute run time for benzene, TCE & PCE Cost ~ 1/5 of TO-15

24 Forthcoming VI Events AWMA VI Conference Denver: Oct 3 & 4 AEHS Conf San Diego: March 18, 2013 EPA all day workshop Petroleum VI all day presentations Half-day session on non-petroleum VI

25 Blayne Hartman, Ph.D. Hartman Environmental Geoscience Still With H&P Mobile Geochemistry