Step 1: Do Exclusion Criteria Exist? Soil Phase TPH Oxygen in Vadose Zone CA & NJ for sure Soil Headspace PID Data (<100 ppmv) Some sites may not have the soil phase data or oxygen data to screen out. Rather than perform a full VI investigation, an intermediate and less costly step is to collect the additional data to determine if the site can be screened out. These data will be primarily soil phase data and oxygen data. These data are far less expensive to obtain than typical vapor intrusion VOC data.. If they do not exist, go to Step 3

EPA-OUST guidance proposed exclusion criteria for UST sites.

CA-LTCP VI Exclusion Criteria 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 Exclusion criteria in the CA Low Threat Closure Policy Bioattenuation zone: TPH-soil < 100 mg/kg 3

NJDEP Gasoline Exclusion Criteria VI Investigation is not required when: ≥10 ft between water table and foundation and benzene in GW is ≤1,000 μg/L; or ≥5 ft between seasonal high water table and foundation, oxygen levels measured at ≥2% (v/v), and benzene in shallow GW is ≤1,000 μg/L. The presence of oxygen drops the separation distance in NJ by a factor of 2. O2 Drops Separation Distance from 10’ to 5’

Step 2: Collect “Screen-Out Data” Soil Phase TPH Oxygen in Vadose Zone CA & NJ for sure Soil Headspace PID Data (<100 ppmv) Some sites may not have the soil phase data or oxygen data to screen out. Rather than perform a full VI investigation, an intermediate and less costly step is to collect the additional data to determine if the site can be screened out. These data will be primarily soil phase data and oxygen data. These data are far less expensive to obtain than typical vapor intrusion VOC data.. Soil Gas VOC Data – not required at this step

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 1,000 ug/L Soil gas SLs increase by 1000x! If you have oxygen data, separation distance drops and allowed soil gas levels increase. TPH-soil required for all scenarios but O2 not 6

A rail yard in the middle of a neighborhood with diesel contamination throughout. Are the homes at risk? 7

Clean Soil Model for HC Vapors Bio-barrier Reaction Zone Conceptual model for clean soils shows that above the hydrocarbon reaction zone there is no more hydrocarbon vapor migration if there is oxygen present. The key to identifying if sites are clean or dirty is to determine if there is sufficient oxygen present in the vadose zone over an interval of several feet.

O2 Profiling - Approach 18 Locations Throughout Neighborhood Vertically Every Foot Down to 8’-10’ bgs Used direct-push (not PRT) Oxygen by portable meter (& CO2 & CH4) Soil Samples at 1’ & 5’ bgs – (backup) Did All Locations in 11 Hours! A real case history to demonstrate a novel vapor intrusion assessment process for a petroleum site at a State with exclusion criteria. The idea was to document the presence of clean soil and use that to exclude out receptors. Soil gas sampling for oxygen using field calibrated meters and collection of soil samples for TPH to confirm the presence of clean soils. These data can be collected inexpensively with great coverage.

Methods to Assess VI Indoor Air Sampling Groundwater Sampling Soil Phase Sampling Predictive Modeling Measure Flux Directly Soil Gas Sampling Supplemental Tools/Data These are the primary techniques/tools used to assess the vapor intrusion pathway. 10

Approach Generalizations Indoor Air Always find something Multiple sampling rounds Groundwater Data Typically over-predicts risk Soil Phase Data Typically not allowed; over-predicts risk for HCs Soil Gas Data Best Data to Collect for PVI Assessment Each investigatory approach has pros and cons that must be considered before choosing the one to use at a site.

Step 3: PVI Specific Sampling Issues Soil Gas VOC Analysis Benzene, ethylbenzene & naphthalene TPH?? Might Need to Sample <5’ bgs If samples >5’ bgs exceed allowable levels How to know? On-site analysis best If not, collect samples anyway Always Collect Oxygen Data There are some differences in soil gas sampling for petroleum hydrocarbon VOCs than for chlorinated solvents. The COCs need to be determined and vary from State to State. If samples at deeper depths exceed allowable values, shallower samples (<5’ bgs) may need to be collected to document the effect of bioattenuation. Oxygen data should always be collected to the document presence of the aerobic zone.

Soil Gas Temporal Study – EPA-ORD 15’ bgs 8’ bgs This is a plot of data recently collected for an EPA funded study by an automated instrument at at Vandenberg AFB site from three probes at the same location but at different depth (3’, 8, & 17’ bgs). This plot consists of over 500 points per probe collected once per hour over a 4 week period from mid March to mid April 2007. The soil gas concentrations varied by less than 10% over these four days even for probes only 3 feet below the surface. 3’ bgs

Ingredients for Effective VI Assessments Investigatory Approach Determine Correct Screening Levels Sample & Analyze Properly Know & Use Supplemental Tools Demonstrating Bioattenuation The keys to effective vapor intrusion assessments are picking the proper approach, determining the correct screening levels, sample & analyze correctly and efficiently, know when and how to use supplemental assessment tools, and to know how to demonstrate bioattenuation if petroleum hydrocarbons are the COC.

The Most Important Ingredient Experience: Consultant Collector – done soil gas before? Lab – certified for methods? Regulator Public YOU! The most important ingredient for cost effective and efficient VI investigations is the experience of the person/firm doing the collection. Is the collection being done by a firm that has prior experience? Is it a routine part of their services or an occasional part? Do they put experienced people in the field who can think or junior staff who aren’t well versed? This applies to the consultant and their subcontractors. What level person is going in the field? 15

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 The most common mistakes made by inexperienced practitioners conducting vapor intrusion assessments.

Wrong Screening Values It Won’t Happen To Me … Uncertifed Lab Wrong Screening Values Incorrect Units RLs Not Low Enough A typical example of a consultant mixing up units & screening levels. Units: ppmv

It Won’t Happen To Me #2… All final vacuums at 0 An example of an inexperienced consultant making mistakes on a COC. All deployed & retrieved at exact same minute!

Long Term IA Samples Maximize Your Chances to Fail the VI Pathway VI Assessment Point #1: Long Term IA Samples Maximize Your Chances to Fail the VI Pathway

Longer Collection Times: Increases Odds of False Positives Passive IA Collectors Examples of passive indoor air collectors Longer Collection Times: Increases Odds of False Positives

Longer Collection Times = False Positives Got A Life? VOCs, especially hydrocarbons, are ubiquitous in all the products that we use everyday. Longer Collection Times = False Positives

Shampoo & Conditioner Compound Shampoo Conditioner Cancer (µg/m3) Noncancer (µg/m3) 1,4-Dioxane 87 -  0.490 31 Chloromethane 170 88 n/a 94 Ethyl acetate 6,500 120 73 Isopropylbenzene 280,000 420 (C9-C12) Aliphatics 11,000 32,000 0.54 1000 According to European and Canadian reports, carcinogens are in almost every brand

Soda Interesting Fact: Compound Soda Pop Cancer (µg/m3) Noncancer (µg/m3) (C5-C8) Aliphatics 260 13 630 (C9-C10) Aromatics 1,000 n/a 3.1 (C9-C12) Aliphatics 16,000 0.54 100 Interesting Fact: It is a well studied fact that Benzene is in soda pop (combination of a benzoate preservative and citric acid, especially in warm/light conditions)

Silly String C5-C8 Aliphatic 7,000,000 ug/m3! Benzene 23,000 ug/m3!

Is Sub-Slab Sampling for the Birds? VI Assessment Point #4: Is Sub-Slab Sampling for the Birds?

SS Data Are Poor Predictors of IA!! Why Not Sub-Slab? Large Spatial Variation Under Slabs What Value to Use? Poor Correlation with Indoor Air SS SLs Can Be < Ambient Air Problems with using & interpreting sub-slab data include the large spatial variation under the slab (10x to 100x), whether to use the highest value or lowest value and the poor correlation between sub-slab concentrations and indoor air concentrations. SS Data Are Poor Predictors of IA!!

Indoor Air & Sub-slab Vapor -- TCE 1:1 10:1 100:1 Attenuation factors from the NY Endicott site show large variation from 1 to 0.001 further complicating what value to use in interpreting sub-slab soil gas results. Further, the data points show no correlation with each other, implying that sub-slab values are not a good predictor of indoor air values. 100*Cbkgd

TPH Compounds Typical Some States: BTEX (BE only risk drivers) Methane Naphthalene (risk about same as benzene) Some States: Aliphatics (C5-C8 & C9-C18) Aromatics (C6-C8 & C9-C16) 1-2 dichloroethane (EDC) & 1-2 dibromoethane (EDB) Petroleum compounds of concern vary from State to State. Consult the oversight agency’s specifications. TO-17 gets PVOCs, TPHg, TPHd in same run!!

TPH Analysis Considerations Laboratory Issues Has does the lab calibrate? Do they subtract out non-HCs? What volume of sample do they need? FID Based Methods (TO-3, 8015) Can’t distinquish non-HCs from HCs Will over-report Certified? Measurement of TPH aliphatic groups at such low levels will introduce a whole new set of potential problems. How do the labs calibrate & process the TPH analyses. This can lead to big differences in reported results. Mass spec methods are advantageous as they allow non-hydrocarbon compounds to be identified and subtracted from the reported TPH value. Best to Use a Mass Spec Method (8260, TO-15, TO-17) 29

Previews of the PVI Future PVI Unlikely at UST Sites PVI More Likely if Shallow Contamination EPA OUST Guidance Coming Out? ASTM Standard Increase # of Sites Here are some predictions & previews of the vapor intrusion pathway for the next few years. But is the Real Future …. 30

Forthcoming VI Events Go to www.hartmaneg.com Sold Out! 2-Day VI Course – Knoxville March 31, 2015 2-Day VI Course – Chicago May 28 & 29, 2015 At Argonne Nat’l Lab Fall 2015: Texas (Dallas or Austin) Louisiana Sold Out! . Go to www.hartmaneg.com 31