# Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System; 40

CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft)

External Peer Review Record (modified) November 21, 2011 – February 20 , 2012

Contents

Peer Review Charge Questions

Summary Matrix of Peer Review Comments on Preamble

Summary Matrix of Peer Review Comments on Charge Questions and Proposed Rule

Peer Reviews

• Tonia Burk

o Charge Question Comments

o CV

o COI Certification

• Blayne Hartman

o Charge Question Comments

o CV

o COI Certification

• Paul Johnson

o Charge Question Comments

o CV

o COI Certification

### • Kimi Klein/Dot Lofstrom (Joint Review)

o Charge Question Comments

o CVs

o COI Certifications

• Henning Larsen

o Charge Question Comments

o CV

o COI Certification

# Peer Review Charge Questions

### Peer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a s ubsurface intrusion (SsI) component to the Hazard Ranking System (HRS). S ubsurface intrusion is the migration of hazardous substances from the unsaturated zone and/or the surf icial ground water into overlying structures. The HRS is the principal mechanism the EPA uses to evaluate site s for placement on the National Priorities List (NPL). The subsurface intrusion component addition (this add ition) would primarily expand the number of available options for EPA and state and tribal organizations pe rforming work on behalf of EPA to evaluate potential threats to public health and the environment from releases of hazardous substances.

This addition will allow the HRS evaluation to directly consider human exposure to hazardous substances that enter building structures through subsurface intrus ion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relative potential risk. The Agency is not considering changes to the remainder of the HRS except for minor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System should include expertise in:

Federal Agency Panelist : Panelist must have a strong working knowledge of policy and technical issues related to topic of vapor intrusion. Knowledge of r ecent developments in vapor intrusion technologies and research is required, in addition to working knowledge of federal vapor intrusion response programs. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous s ubstances is necessary. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

State Environmental Program Panelist: Panelist must have strong technical experience and working knowledge of policy and technical issues (e.g., mitigati on and remediation) related to the topic of vapor intrusion. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile h azardous substances is necessary. Knowledge of recent developments in vapor intrusion technologies and research is required, in addition to working knowledge of state vapor intrusion response programs. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience related to conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

Academia: Panelist must have experience working, researching, and developing opinions on the topic of vapor intrusion. Expertise in the history and recen t developments of vapor intrusion research and development, remediation, and mitigation technologies is required. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous substances is necessary. Experience worki ng on Superfund issues is highly recommended, but not

necessary.

### Panelist from non-specified sector: Panelist must have a strong working k nowledge of policy and technical issues related to the topic of vapor intrusion. Knowledge of recent developments in vapor intrusion technologies and research is required, in addition to working knowledge of federal vapor intrusion response programs. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous substances is necessary. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

Peer Review Charge Questions

1. Potential for subsurface exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a rele ase of a hazardous substance when an actual release has occurred through either chemical analysis or direct observation. The current HRS also evaluates the potential for a release to occur within the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is determined by the consideration of pathway specific factors that aid the site evaluator in predicting whether a release to the pathway is likely to occur. These factors are based on containment features of the source of contamination (whether or not hazardous substance can get out), route characteristics specific to each pathway (how far hazardous substances could migrate based on knowledge of site conditions) and include physical/chemical properties of the hazardous substances being evaluated (how the hazardous substances act in the environment).

Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure of
intruded hazardous substances for the subsurface intrusi on addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the Johnson-Ettinger m odel and also considered multiple lines of evidence approaches which estimate the levels of contaminant exposure based on numerous route characteristics. In addition, EPA examined the relationship between these factors to determine which have the greatest influence on the likelihood that an exposure would occur, and then incorporated these factors within its proposed approach. EPA also gave careful consideration to ensure that the data necessary to obtain route
characteristic factors could be measured or calculated on a site-specific basis and in a manner consistent with current HRS evaluations. Based on the Agency’s analysis, the following three factors for which sufficient site-specific information could be collected during a site inspection represented the greatest impact on the potential for exposure: (1) depth to contamination; (2) vertical migration; and (3) vapor migration potential (see Figure 1).

### Figure 1

Charge Question #1 : Is EPA’ s p roposed approa ch scientifically reasona ble for evaluating and assigning proportional weightings for the following whe n evaluating potential for exposure ? If no, what al ternative approach would you recommend?

a. Consideration of the construction/structure type for which sufficient site-specific information could be collected during a site inspection for the occupied structure;
b. Distance be tween occupied structure and depth of contamination; and c. Evaluation of the vertical migration factor based on the thickness and porosity /permeability of geologic materials in the interval between the lowest point of an occupied structure and the highest known point of hazardous substances in the subsurface.

### 2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity factor reflects the risk consideration related to the magnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pathways. At each site evaluated, EPA uses a four-tiered hierarchy for calculating the hazardous waste quantity that is based on (1) constituen t quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original sources (how much has migrated and how much can be released in the future). In the soil exposure pathway, the hazardous waste quantity does not include the total amount of hazardous substances in all site sources, but rather is based on the amount of hazardous substances to which a receptor can be exposed where actual contamination has been documented. In other words, for the soil exposure pathway, the risk posed by a release of hazardous substances is directly related to the amount of hazardous substances that receptors are exposed to, as opposed to how much of the hazardous substances from the original sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrusion a ddition to the HRS. Since the subsurface intrusion component also focuses on exposure, the waste quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar four- tiered hierarchical approach to calculate hazardous waste quantity within occupied structures with contaminat ion. In cases where no home is subject to actual contamination, EPA is proposing to use minimum waste qua ntity factors. In situations where there is an observed release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantity factor value. This value is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and air pathways and reflects the increased exposure risk of a release within an occupied structure.

Charge Question #2: Is EPA’s approach of basing the hazardous waste quantity on the amount of contaminants that could be found in the intruded structures appropriate? If no, what alternative approach would you recommend?

### 3. Population score Background: Within the current HRS, receptors are evalua ted in two main categories: whether they ar e exposed to 1) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting obs erved release criteria, they are identified as actually contaminated; however, if the receptors are not expose d to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially contaminated. Actual contamination is further divided into two sub-categories based on whether the hazardous substance is present
at or above a health-based benchmark. If the concen tration of the hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multiplied by a factor of 10) in scoring. If the release concentrations are less than a health-based benchmark, the receptors are identified as Level II recepto rs and are not weighted (multiplied by a factor of 1). Potential receptors are distance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to the site score.

Proposed Approach: EPA is proposing to generally use the same receptor weighting structure in the subsurface intrusion component as the one used in th e current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in the area(s) of subsurface contamination (ASC) are considered potentially contam inated (See Figure 2). The receptors in an AOE are
further differentiated based on whether the contaminant concentrations are at levels above identified benchmarks (Level I) or are at levels establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use fo r the subsurface intrusion component are:

• Screening concentration for cancer effects; and

• Screening concentration for non-cancer effects (systemic toxicants).

Consistent with the weighting of populations throughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II contaminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of targets within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential receptors within the ASC receive less weight (population multiplied by a factor of 0.1), except in cases where a sub-slab sample indicates contaminant levels are at least 10 times higher than a health-based benchmark (population is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting reflects the observation that for approximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustment applied to the health-based benchmark reflects EPA’s finding that, in such paired sampling events, the indoor air sample concentration is, on average, 10 times lower than the sub-slab sample concentration.

### Figure 2

Charge Question #3: Is i t appropriate to consider individuals/populations located within the area of subsurface contamination (ASC) to be at a higher relative risk in situations when sub-slab contaminant concentrations are at least ten times greater than a health-based benchmark? If no, please explain.

### 4. Multi-story and multi-tenant structures Background: In the current HRS, multi-story and m ulti-tenant buildings are evaluated based on population associated with an actually or potentially impacted target. In the ground water pathway, all residents who are served by a well are considered subject to the actual or potential contamination of the well. In the air pathway, all residents who have an opportunity to breathe ambient air are considered subject to the actual or potential contamination of the ambient environment w ithin a distance category. All receptors within a contaminated surface water stretch are subject to the level of contamination associated with that surface water stretch. In the soil exposure pathway, receptors must be able to come in contact with areas of contamination. In determining the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/use areas within a 200 foot areal extent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multi-story (the assumption being that is reasonable for people to use the outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story/multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenant/m ulti-story building. EPA is proposing to consider all receptors exposed to actual contamination as the population inhabiting the floor of the int ruded space and the population inhabiting the floor above and the floor below the intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, while also minimizing the potential for over counting (Figure 3).

Figure 3

### Charge Question #4: When calculating waste quantity and population, is it scientifically reasonable for populations in multi-story or multi-tenant structures to be evaluated based on using only the population inhabiting the intruded space and the population on the floor above and below the intruded space (For example, if contamination is found on the first floor, population from the basement and second floor would be used in the calculation. If contamination is found on the fifth floor, population from the fourth floor and
sixth floor would be used in the calculation – for fu rther explanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, what alternative approach would you recommend?

### 5. Factor Value for Workers Background: In the current HRS, for the resident p opulation threat of the soil exposure pathway, a factor value for workers is assigned based on the total number of workers present within the area of observed contamination. These factor values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker factor va lue in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). However, since it is anticipated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamination, EPA is proposing to assign workers exposed to subsurface intrusion a higher weighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to su bsurface intrusion within the workplace than it is for workers exposed to outdoor surface contaminat ion at the workplace? If no, please explain.

# Summary Matrix of

Peer Review

Comments on PreambleCommenter GuidanceSectionLineNumberComment EPA ResolutionBurk VI.B.2.b. 824 ParentheticalComment: Reference Section 5.2.1.3.2.3 for weightingBurk VI.B.3. 842Consider replacing “this” with “observed exposure (section 5.2.1.1.1.)”Burk VI.B.3.a.ii 887-888 Comment: Consider using reference values as a first line of comparison, instead of nearby sampling data.If indoor air background occurs outside thearea of release, what would the source(s) be? Many are totally dependent on individual occupants’ lifestyles and choices and likely vary from onehouse to the next: use of household products (hobbies, cleaning, home/auto/garden maintenance), use of heating oil, cooking habits, homebusinesses, attached garages, and worker take-home exposures. Background sources that may come from regional sources could includevolatilization from household water use from asimilar water source, outdoor air, or subsurface sources from non-site related hazardous wastegenerators. However, most of these regional sources could be accounted for independently. Literature data is more likely to capture statisticallysignificant sources from individual occupant sources than select samples in the region of the site under investigation. Also not discussed in thisPreamble or the HRS Rule documents are whether background implies the average concentration, UCL or maximum levels.Reference to guidance on selecting background values could beprovided (http://www.epa.gov/oswer/vaporintrusion/documents/oswer-vapor-intrusionbackground-Report-062411.pdf), if explicit discussion is not. This reference includes data from thousands of indoor samples with statistical review torepresent the wide range of behaviors and contributors to background indoor air contamination.BurkVI B 3 a ii894Consider adding:“Furthermore the background of some contaminants is expected to be negligible”VI.B.3.a.iiConsideradding:Furthermore,thebackgroundofsomecontaminantsisexpectedtobenegligible.Burk VI.B.3.a.ii 898Consider adding “(or the similarity)” [...that the differenceor the similarityis not simply...]Burk VI.B.3.a.ii 898-900 Extreme temporal and spatial variability is also a hallmarkof the vapor migration pathway due to barometric pumping and other more subtle yetcomplex factors, such as HVAC operation, opening a window, varying soil moisture content, snow/ice cap of the surrounding surface, and seasonaleffects, to name only a few examples. Note should be made within the document that such untraditional factors can play a significant role in SsI on anhourly, daily and monthly basis and should be noted in site assessment for NPL listing. Perhaps this can be reflected in the technical document.Burk VI.B.3.a.ii 906Consider inserting “a pre-determined” after "below" [...background level is belowa pre-determineddetection, any level...]Burk VI.B.3.a.ii 906Consider inserting “limit” after "detection" [...detectionlimit, any level...]Burk VI.B.3.a.ii 929-931This situation can get complex and may warrant further discussion in the technical document. While it issufficient to indicate if an environment issignificantly higher than background, should the background be elevated with regard to health or quality parameters, any elevation above those levelsshould be deemed “elevated.” Also, let’s not forget about false negatives. If a GW plume has VOCs and indoor air at several residences has a cadre ofthose VOCs , and the indoor air is above a benchmark, then we should consider the exposure from the CERCLA source is significant, unlesshousehold sources are removed and levels found to be below levels of concern.Burk VI.B.3.b.v. 1033Delete second "to be" [...projected to be to bethe most...]Burk VI.B.4.b. 1089Remove "s" from "pathways"Burk VI.B.4.b. 1100 Change "potions" to "portions"Burk VI.B.4.b. 1108 Change "adequate" to "adequately"Burk VI.B.4.b. 1121Consider changing "occur" to “be detected” [subsurface intrusion wouldbe detectedif sampling...]Burk VI.B.4.b. 1126Consider changing "actual" to “indoor air” [...sampling would documentindoor aircontamination.]1280 1281f 0 ?C0 80 f 0ff fBurk VI.B.5.c.ii 1280-1281What is the basisor using 0.75?Consider using 0.80 instead o.75. It is more conservative and it is the actual value reerenced here. Isite-specificdata is available, such as for a nearby AOE, perhaps consider that percentage.Burk VI.B.5.c.ii 1284Will additive effects forgeneric types of contaminant VOCs and sVOCs be taken into account?Hartman I.B 170-171[Response to statement: "The EPA does not expect that this proposed change will result in additional site assessments being conducted."] Oh yes itwillHartman I.B 174-175[Response to statement: "For these reasons, the EPA considers thatthis proposed rule is not expected to result in the listingof more sites on the NPLduring any particular time period."] It definitely willHartman I.B 183-184 The proposed rule is not compliant with the current & updated EPA-OSWER & EPA-OUST vapor intrusion guidances.Hence all this is going to do iscreate more confusion.Hartman III.A 241-243This is deceptive. Because vapor intrusion screening levels are so low, the benchmarks the rule proposes to use, sites that are really not a huge riskwill possibly score high in the HRS.Hartman III.A 243-245 Only true for sites with only vapor releases, but not sites with soil & groundwater contamination. Your current system will catch these just fine.Commenter GuidanceSectionLineNumberComment EPA ResolutionHartman III.A 251-252[In response to statement: "Over 40 written comments were received during the public comment period."] Thisis a tiny number of comments from acountry with millions ofpeople that could be affected by this new rule.Hartman III.A 252-253Your first line says ”because of the substantial public support.” But here you admit that of 40 comments, some were from government agencies. Thisis not the public. Just how many comments were actually from non-government agencies? This means that less than 40 comments were received.Seems to me that the public doesn’t really care about this proposed new rule.Hartman III.A 255-2565 out of 50 states says to me that the 90% of the States are not interested in this new ruleHartman III.A 256-258ASTSWMO is NOT supportive of this rule for petroleum hydrocarbons. Your rule makes no distinction for petroleum vs. non-petroleum VOCs.Hartman III.A 261-263But didn’t you say previously on lines #171 & #174 that this new rule would not result in additional site investigations? You’re saying an additional 850sites won’t result in more investigations?Hartman III.A 283-284Lines #171 & #174 say that the new rule won’t lead to additional site assessments, but here you admit there willbe more.Hartman III.A 286-289[Regarding public support]: This is debatable as commented on above.Hartman III.A288[Regarding national program consistency]: Don’t the State Environmental regulatory agencies oversee this?Hartman III.C 390-391I disagree with this statement.Hartman III.C 404-405But your new rule is inconsistent with the EPAvapor intrusion guidance in some areas.This will create more confusion, not less.HartmanIII.C415-[Regarding imposing costs on private entities]: But is likely the inevitable end-result.Hartman416[Regardingimposingcostsonprivateentities]:Butislikelytheinevitableend result.Hartman IV.B.2 488-489This is where the rule is really lacking. Petroleum hydrocarbon VOCs behave very differently than halogenated VOCs, but there is no distinction in theproposed rule.Hartman V.A.2 569-572This ITRC survey is out of date. Between 35 to 40 States now have their own vapor intrusion guidanceHartman V.A.2 574-575[Regarding ASTSWMO support]: Not for petroleum hydrocarbon sites.Hartman V.A.3 605-607Tiny number of comments from a nation this large. I consider this to not indicate a large public connern over this pathway.Hartman V.A.4 628-629[Regarding "placeholder for topics identified as needing peer review"]: Would be nice to know what these topic are.Hartman VI.B.3.b.v. 1029-1030This is where the rule is lacking.For hydrocarbon VOCs, bioattenuation willgreatly reduce the migration potential, but your rule makes no allowancefor that.Hartman VI.B.4.b. 1120-1122But again, this needs to be broken down into hydrocarbon VOCs and halogenated VOCs? This 80% should not apply to both compound groups.Hartman VI.B.5.b.i 1203[Regarding "•Screening concentration for cancer"]: The problem here is your are proposing to use abenchmark at 1 in 1 million risk level.This is fartoo low and will be easily exceeded. Some States regulate this pathway at 1 in 100,000 and some at 1 in 10,000. It is advised that you use abenchmark at the 1 in 10,000 risk level to avoid listing too many sites with a low potential for VI problems.Hartman VI.B.5.b.i 1204[Regarding "• Screening concentration for noncancer toxicological responses"] With new toxilogical data recently released, even the noncancer values(HI=1) are very low. Again, you will be listing too many sites if you use this as a benchmark. It is advised that you set non-cancer levels at a HI=10.Hartman VI.B.5.b.ii 1220-1221[Regarding value of 20]: This value seems completely subjective to me. What is the basis? You haveno evidence that this individual is exposed.Hartman VI.B.5.c.ii 1280-1282No, this is the 95th percentile, in the EPA report not the average. The 10x criterion is too low and will result in overranking. It should be at least 50x.In addition, this rule should not apply to hydrocarbon VOCs since the EPA report was based upon halogenated VOCs.H tVI B 5 d1303 1304B t th b h k h ld l b t t bli h d i l f i l/i d t i l t t f id ti l tarmanVI.B.5.d1303-1304Butthebenchmarkshouldalsobe setto publishedscreening valuesfor commercial/industrialreceptors, notfor residentialreceptors.Johnson 9 GeneralCommentI understand the need to generalize and provide flexibility todeal with any intrusion to buildings (gases orliquids), but 99%of the preamble discussionis specific to vapor intrusion and is not relevant to intrusion of liquids. This should probably be mentioned and the emphasison vapor intrusion in thediscussions of specifics should be stated up front.Johnson Summary 25-26To be consistent with other USEPA documents, should this state “The NPL is a list of national priorities among the known releases or threatenedreleases”?Johnson Summary 30I can understand this addition to the HRS not affecting the current placement of sites on the NPL, but couldn’tit make a difference as to whether or nota “proposed” site is selected for the NPL?JohnsonI.B163“contaminant” is redundant, given the definition of “subsurface intrusion”given above.JohnsonI.B 170-171[Regarding "TheEPA does not expect that thisproposed changewill result inadditional site assessments beingconducted."]: Is this true? It seemsthat many sites do not have the appropriate data to assess the pathway. For example, I work close to a site that has been on the NPL list for morethan a decade and that has in the last year conducted a new off-site site assessment specific to this pathway. See also lines238 - 245 and 265-275below.Commenter GuidanceSectionLineNumberComment EPA ResolutionJohnson III.A 224-225[Regarding "The most common form of subsurface intrusion is vapor intrusion."]: What other forms are anticipated?Johnson III.A230Is “relative” necessary or appropriate here? If so, should you add “compared to other sites” as is done below to clarify what the risk is relative to?Johnson III.A233[Regarding "exposure"]: Should you say “contact or ingestion” here to be consistent with the sentence structureand later discussions?Johnson III.A261[Regarding "the subsurface"]: Should you insert “scope of”, “breadth of” or “scale of” here?Johnson III.A 265-275 Bulleted Text Are any of these sites ones where it is something other than vapor intrusion? It would be useful to clarify that.Johnson III.A280[Regarding "...nor does the EPA have any specific subsurface intrusion sites for the NPL identified at this time..."]: Is this true? What about Motorola52nd Street site? They are devoting a lot of effort now to look at this pathway.Johnson III.A 280-283This seems to conflict with earlier statements about how addition of this pathway is unlikely to change thenumber of sites on the NPL.Johnson III.C350[Regarding "gas, vapor"]: Are “gas” and “vapor” different things to the authors? They mean the same to me.Johnson III.C383[Regarding "is operated strictly by the public sector"]: Is this a true statement? There are DoD (non-public sector) sites in the program and many siteassessments are reviewed and commented on by EPA and its contractors.Johnson III.C 389-391The reasoning here is a little strange – basically it’s saying that the number of sites on the NPL is constrained by resources and is not dictated by therisks posed by the sites. It is not clear why this concept is needed in this preamble or why it is repeated often? Isn’t themore important issue whetheror not evaluation of thispathway will lead to more cleanup or the identification of more sites requiring further study (ratherthan does the number ofsites on the NPL grow)? The GAO reported seemed to anticipate the potential growth in the number of sites resulting from consideration of thepathway.Johnson III.C 392-394What evidence do you have to back this up? There are a few well-known sites with exemplary programs (e.g., Hill AFB), but probably many others thathave not yet even looked at the pathway.Johnson III.C 400 [Regarding "most states"]: Is “most” a true statement at this point in time? I can think of “a few” or “some” that have made it a high priority. See lines569 – 577 below as contradictory statements.Johnson V.A.2 565 [Regarding "non-federal"]: Is it assumed here that there is a comprehensive program for evaluation SsI at federal sites? If so, what is that program?Johnson VI.B.2.b. 820 Lines 817-819 indicate that that the ASC is based on known subsurface contamination, so why include the line“but either sampling has notdocumented that subsurface contamination has occurred..”?Johnson VI.B.3.a.ii 887-894 Howwill youdeal with the situation where health levelsof concern are at or below background levelsfor some settings?Johnson VI.B.3.a.ii 904-905 [Regarding "three times the background level"]: Why 3X? If I measure background at about 0.2 ug/m3 and I get 0.4 ug/m3 results and health levelsare 0.2 ug/m3 , is this the right conclusion? These issues will be important for this pathway (more so than for other pathways) because manymeasured values, background levels, and levels of concern are likely to fall in the 1X – 10X real detection/reporting levels.Johnson VI.B.3.a.ii 906-907 Even if 10% above detection levels?Johnson VI.B.3.a.ii 919-923 Note that our research has shown that indoor air sources can themselves cause subsurface contaminationthrough building “breathing” with the soil.So simply looking for the presence indoors and in the subsurface does not conclusively prove that indoor concentrations are resulting from SsI.Johnson VI.B.3.a.ii 929-931 This section’s discussion is predicated on the assumption that not seeing a chemical in typical indoorair sampling results is evidence that SsI is notoccurring. Our detailed field study data from Utah has shown that to not be true. Probably need to mention that this issue isbeing addressed below inlines 934 – 937.Johnson VI.B.3.b 940 This “samplin” seems to assume that all samlinis of thepoint-in-time andpoint-in-space type(e.g. Summa cannisters). There are other methodsgpg pp p yp ( gthat may prove to be more reliable in the next few years. The language should allow for the development of new methods and maybe needs to bespecific to say that it is considering conventional sampling approaches as the current norm.Johnson VI.B.3.b 944-945 Good point and this paragraph is pretty well written and important.Johnson VI.B.3.b 949 Note that this figure [5] only shows vapor intrusion and not any other anticipated “subsurface intrusion” routes.Johnson VI.B.3.b.ii 991-992 [Regarding "depth to contamination"]: This one should probably be replaced with chemical type. Whether or not a chemical is aerobicallybiodegradable is a much more significant factor than depth (see comment below) and modeling and empirical data show this to bethe case.Johnson VI.B.3.b.iii 996-1003I have concerns about this factor. In theory, for non-biodegradable chemicals, depth can at most affect the flux rate linearly (e.g., the flux rate for asource 200 ft deep would only be 10X less than one from 20 ft deep, and there would be even less difference if the soil profilewere not the controllingdiffusion resistance (i.e., if the capillary fringe or the building structure wereinstead the controlling factors). The EPA empirical database also does notshow a strong dependence on depth, if I remember correctly.Commenter GuidanceSectionLineNumberComment EPA ResolutionJohnson VI.B.3.b.iv 1019-1022I would like to see the back-up for this. As shown in EPA guidance document modeling and other workthat we have published in the past, soil typedoes not have a significant effect on effective diffusion coefficients. 10000X differences in permeability might only correspond to 10X (at most)differences in diffusion coefficients. The one thing (perhaps the only thing) that will make a significantdifference is thepresence of perched waterbetween the vapor source and building or the presence of a highly water saturated soil layer. The EPA empirical database alsodoes not show a verysignificant effect of soil type.Johnson VI.B.3.b.v 1034-1037This should focus more on some combination of vapor pressure, Henry’s Law constant, site concentrations, and threshold breathing levels as it is notalways the most volatile chemical that poses the greatest health threat.Johnson VI.B.4.b 1119[Regarding "waste quantity"]: Wouldn’t it make more sense to have this factor related to either groundwateror soil gas concentration?Johnson VI.B.4.b 1123-1124See comment above concerning the connection between indoor air sources and subsurface vapor clouds. The former has been shown to be capableof causing the latter.Johnson VI.B.5.a 1167-1169This makes sense.Johnson VI.B.5.b.i 1189[Regarding "outdoor"]: Do you mean “outdoor” or “exterior” sampling. The former implies above-ground sampling, while the latter is the EPA guidanceterminology for sub-slab, subsurface, and groundwater sampling around and beneath a building.Johnson VI.B.5.c.i 1251-1253This seems reasonable for this pathway, although I’d expect some people to object.Johnson VI.B.5.c.ii 1279-1282Note comments above concerning indoor air sources and subslab vapor concentrations – this high correlation is expected in cases of indoor sourcesas well as for subsurface sources, so the relationship is not unique nor proof that subslab detections are proof of a complete subsurface to indoor airpathway.Lofstrum/Klein 13 GeneralCommentIt should be made clear from the outset that the ‘hazardous substances’ referred to in the proposed subsurface intrusion component are thosesubstances that can volatilize and migrate through the subsurfaceto inhabited structures. Thisis not made clear at all in this preamble.Lofstrum/Klein III.A 225There are several places where the term ‘EPA’ is used instead of ‘the EPA’. It should be ‘the EPA’Lofstrum/Klein III.A 235-236How would contaminants from surface water bodies enter indoor air spaces?Lofstrum/Klein III.A 247Replace with ‘Second, the” and delete ‘is’ before 'because' to be consistent with the first paragraph on this page. [Sentence should read: "Second, theEPA is offering today’s proposalbecauseof the substantial..."]Lofstrum/Klein III.A260Replace with ‘Third,”. [Sentence should read: "Third,the EPA has..."]Lofstrum/Klein III.A260Replace with ‘evaluated’ [Sentence should read "...the EPA hasevaluated..."]Lofstrum/Klein III.A261Replace with ‘by identifying the magnitude of”. [Sentence should read "...to the current HRSby identifying the magnitude ofthe subsurface..."]Lofstrum/Klein III.C349I think it would be clarifying to add ‘volatile’ before ‘hazardous substances’. Or say ‘hazardous substances that can volatilize’.Lofstrum/Klein III.C350What is the difference between a gas and a vapor?Lofstrum/Klein IV.B474 Figure 2 Define the abbreviations/symbols across the bottom of this figure.Lofstrum/Klein V.A.1 524Replace with ‘the EPA’.Lofstrum/Klein V.A.1 526Replace with ‘the EPA’.Lofstrum/Klein V.A.1 532Add ‘the’ before ‘Resource’.Lofstrum/Klein V.A.1 547Replace with ‘are’. ['...intrusion issuesareevaluated..."]Lofstrum/Klein V.A.2 575Define. [ASTSWMO]Lofstrum/Klein V.A.2 579Delete. ['In addition']Lofstrum/Klein V.A.2 581Define.[ATSDR]Lofstrum/Klein V.A.2 584Add ‘the’ before ‘ATSDR’.Lofstrum/Klein V.A.2 586Make this a period. Start a new sentence. [Sentences should read: "...uniformly and consistently.Itis highly resource intensive..."]Lofstrum/Klein V.A.4 628Replace [agency] with ‘EPA’.Lofstrum/Klein V.A.4 629Replace [agency] with ‘EPA’.Lofstrum/Klein V.A.5.5 645This sentence should be changed to match the style of the other points. Like ‘Assemble and rely upon existing data to test the model.’.Lofstrum/Klein VI.A723This paragraph shouldinclude a discussion ofground water and how the proposalwill notoverlook ground water as a source of hazardous substanceswith the capability of intruding into indoor air spaces.Lofstrum/Klein VI.A724Replace ['are consideration of'] with ‘consider’.Lofstrum/Klein VI.B.2.b. 814The approach for evaluating the area of subsurface contamination should be revised to include the ability to evaluate sites with subsurfacecontamination but without current structures.Lofstrum/Klein VI.B.3 836Delete the comma. [After 'HRS']Commenter GuidanceSectionLineNumberComment EPA ResolutionLofstrum/Klein VI.B.3.a 850The terms contaminant and hazardous substance are used interchangeably throughout this preamble. When possible, ‘contaminant’ should bereplaced with’ hazardous substance’, because this term is what is used in the proposed regulations, and it cannot be confused with other similar wordslike ‘containment’ to the tired reader.Lofstrum/Klein VI.B.3.a.i 862Why call out solid and liquid when only gas is addressed in the proposed revision to the HRS regulations?Lofstrum/Klein VI.B.3.a.i 865Same comment as previous [Why call out solid and liquid when only gas is addressed in the proposed revision to the HRS regulations?]. If not deleted,it should be clarified that the solid or liquid would contain a volatile hazardous substance(s).Lofstrum/Klein VI.B.3.a.ii 904Replace ['considered'] with ‘assumed’.Lofstrum/Klein VI.B.3.a.ii 919Delete this phrase ['It is suggested that'] and add ‘should’ before ‘include’. ["The evidence to support this determinationshouldinclude..."]Lofstrum/Klein VI.B.3.a.ii 923Delete. ['In addition,']Lofstrum/Klein VI.B.3.b 955 Figure 5 It would be clarifying to add the term ‘Chemical-specific’ to ‘Vertical Migration Factor’.Lofstrum/Klein VI.B.3.b.i 969Change ['of'] to ‘to’. [...'minimize exposuretohazardous substances..."]Lofstrum/Klein VI.B.4.b. 1096Delete. ['ever']Lofstrum/Klein VI.B.4.b. 1108Replace ['insignificant'] with ‘insufficient’.Lofstrum/Klein VI.B.4.b. 1108Replace ['adequate'] with ‘adequately’.Lofstrum/Klein VI.B.5.a 1164-1165This ["Given that the subsurface...intrusion pathway."] is not a complete sentence.Lofstrum/KleinVI B 5 c ii1261The approach to weighting targets should be revised to include evaluating areas of subsurface contamination without structures currently presentVI.B.5.c.iiTheapproachtoweightingtargetsshouldberevisedtoincludeevaluatingareasofsubsurfacecontaminationwithoutstructurescurrentlypresent.Lofstrum/Klein VI.B.6 1351-1352[Regarding: "...incorporation of the pathway score into a site score."]: Does this mean to say ‘how the intrusion pathway scoreis incorporated into thesite score’? If so, this sentence should be rewritten for clarity.Lofstrum/Klein VI.B.6.a 1361 Change ['reflect'] to another word to avoid redundancy in the same sentence. Change to ‘expresses’.Lofstrum/Klein VI.B.6.a 1362 Change ["each of the"] to ‘of each of the’. ["...the magnitude of each of the factor..."]Lofstrum/Klein VI.B.6.a 1363 Change ['probably'] to‘probability’.Lofstrum/Klein VI.B.6.a 1365 Change ['probably'] to ‘probable’.Lofstrum/Klein VI.B.6.b 1374 Delete. ["proposed to be"]Lofstrum/Klein VI.B.6.b 1381 Move this phrase ["using this approach to assigning the pathway score"] to the end of the sentence for clarity and delete ‘to assigning the pathwayscore’.Lofstrum/Klein VII 1396 In Section 2.4.1.1 Toxicity Factor, carcinogenicity is divided into weight of evidence categories: A, B,and C (see Table 2-4). The EPA is no longerusing these categories, so consideration should be given to updating that section as well.

# Summary Matrix of

Peer Review

Comments on Charge Questions and Proposed RuleCommenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionBurk1.aNo mention of the potential for intrusion from wet basements orfactors affecting indoor air pressure and exchange rate, such as HVAC systems orstructural integrity (“leakiness”) of building, was identified. Section 5.2.1.1.2.1 Structure Containment of the HRS Rule document may be an appropriateplace to add consideration of these topics.Burk1.bAgreed, reasonable.Burk 1.cConsideration of the possibility for hydraulic pumping in areas prone to rapid rise of the groundwater table may warrant a higher ranking. For example,vapor intrusion events in Hartford, IL have been correlated with rise in the Mississippi River and, to a lesser extent, rainfall(http://www.atsdr.cdc.gov/HAC/pha/HartfordResidentialCommunity/HartfordResidentialCommunityLHC02-24-2010.pdf).Burk 2Agreed, appropriate.Burk 3Agreed, however, the last bullet in section 5.2.1.2.2 of the HRS Rule document includes enclosed crawl spaces inthis criteria. Since EPA’s defaultattenuation factor for crawl space intrusion to indoor air is 1, the crawl space criteria may be better stated as considering populations when crawl spaceconcentrations are greater than a benchmark (instead of 10 times a benchmark).Burk 4The charge question seems to be worded differently than the description in the HRS Rule document on this topic. The charge question considers only thecontaminated floor and one floor below and above the contaminated floor. Sections 5.2.1.3.2.1 and 5.2.1.3.2.2 say to consider those populations livingwithin the story with Level I/II concentrations and those stories below that story. Section 5.2.1.3.3 says to count those workers in the highest story withobserved exposure, one story above and all stories below. I agree witheither approach with a caveat: preferential pathways, such as elevators andventilation systems, may serve to transport hazardous vapors to distant floors. It may be prudent to consider the possibility of discontinuous contaminationfrom floor to floor and not rule out floorsthat have not been sampled in such cases.Also, if a preferential pathway has not been identified tocontamination in an isolated upper floor, all floors below seem at risk.Burk5Agreed reasonable.Burk1.171Phrases with the term “observed” are used frequently throughout the document but not explicitly defined. Could a more precise definition be includedsomewhere, such as adding Oserved Contamination: The presence of contamination determined by visual or olfactory recognition or chemical analysisand differentiated from background by comparison with background concentrations.Burk2.4.2.2 2336-37Consider changing criteria for crawl space to: greater than its appropriate benchmark, since default EPA attenuation factor forcrawl spaces is 1 (noattenuation).Burk5.2.1.1.1 4520[Regarding background concentration]: More explanation of appropriate use of background or reference to a moredetailed explanation might help here. Amore detailed discussion is provided in the preamble. Consider inserting a reference tothe comments in the preamble or the technical document for amore detailed section on this topic.Burk5.2.1.1.2.1 4537[Regarding structure containment]: Perhaps add a paragraph to thissection explaining the potential significance of wet basements, HVAC systems andstructural integrity (leaky buildings) onstructure containment. These topics are discussed in the ITRC vapor intrusion guidance:http://www.itrcweb.org/Documents/VI-1.pdfBurk5.2.1.2.2 5018-19[Regarding enclosed crawl space]: Consider changing criteria forcrawl space to: greater than its appropriate benchmark, since default EPA attenuationfactor for crawl spaces is 1 (no attenuation).Burk5.2.1.3 5051[Following "...with observed exporure."]: Consider adding: “, unless a preferential pathway exists to higher floors. If a preferentialpathway to higher floorsexists, such as an elevator shaft, count those targets in affected stories, unless information, such as indoor air sampling onthose floors, indicatesotherwise.Burk5.2.1.3.1 5111Consider moving the word “only” to followthe word “observation” [...if there is an onlyobserved exposure by direct observationonly...]Burk5.2.1.3.2.3 524-5Consider the possibility of preferential pathways, such asby elevator shaft, to different floors.Burk5.2.1.3.2.3 526-7Consider changing criteria for crawl space to: greater than its appropriatebenchmark, since default EPA attenuation factor for crawl spaces is 1 (noattenuation).Burk5.2.1.3.2.3 5211Consider changing criteria for crawl space to: greater than its appropriate benchmark, since default EPA attenuation factor forcrawl spaces is 1 (noattenuation).Burk5.2.1.3.3 5222-23Consider the possibility of preferential pathways, such as by elevator shaft, to different floors.Hartman1No, it is not scientifically reasonable using these 3 factors alone.Hartman1.cThis is a better approach than the one written above. However,this approach is also flawed if bioattenuation is not includedinto the vertical migrationfactor/potential. As now written, Section 5.2.1.1.2.3 & 4 & 5 have no allowance for bioattenuation, so the approach is fundamentally flawed for any VOCsthat can bioattenuate such as vinyl chloride and petroleum VOCs.Hartman2This approach is appropriate, but what is not appropriate is defining the level I & II benchmarks at a 1 in 1 million risk level. Much too low. You should setbenchmarks at a 1 in 10,000 risk level.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionHartman3EPA OSWER has released a paper evaluating attenuation factors, including sub-slab to indoor air attenuation factors. The factor of 10 you refer to in theabove paragraph is not an average. It is a 95th percentile. If you are going to usean average as you indicate, than the factor of 10 should be significantlyhigher. A paper released in 2011 says that a more reasonable subslab to indoor air attenuation factor is 50x. So, while it is appropriate to considerindividuals/populations located within the areaof subsurface contamination (ASC) to beat a higher relative risk in situationswhen sub-slab contaminantconcentrations are high, the weighting factor of 0.75 should not apply until sub-slab values are at least 50 times higher thanindoor air values rather than10x higher.Hartman4This protocol is okay so long as there are no elevators in the building or pipe/electrical chases that act as vapor conduits between lower & upper floors.Hartman5There’s no explanation as to wherethe factor of 3 came from. Hence, while itis reasonable to assume the risk is greater, I feel the basis for the factor of3 should be explained.HartmanGeneralCommentThere needs to be a distinction in this rule between petroleum hydrocarbon VOCs which readily bioattenuate and recalcitrant VOCs (typically thosecontaining halogens) that do not bioattenuate. I do not see any allowance for this under vapor migration potential factors.HartmanGeneralCommentOne idea to distinguish between VOCs that bioattenuate versus those that don’t would be to come up with a bioattenuation factor. These factors wouldbe 0.1, 0.01, 0.001, and 0.0 using exclusion criteria that EPA-OUST is now considering.HartmanGeneralCommentSetting benchmarks for cancer effects at 1e-6risk level and for non-cancer at a HI=1 isgoing to suck in almost every site asthe screening levels for manycompounds are below ambient levels. Since your goal is to rankthe highest priority sites, you should set the benchmarks for cancer at 1e-4 risk and nonHI 10 Thi ill li h th HRS l f ki th hi h t i it it b t t b dki ith l b f it t kcancer atHI=10.This willaccomplishtheHRSgoalofranking thehighest priority sitesbut notbogdown your ranking withalarge number ofsites to rankthat are unlikely to havea vapor intrusion concern.Hartman Table 5-13 46 13 GeneralCommentIn some places (such as table 5-13 and section 5.2.1.3.2.3), therule is inconsistent with current & forthcoming EPA vapor intrusion guidances. This ruleneeds to be compliant with the two guidances coming out in March by EPA-OSWER & EPA-OUST.Hartman 5.2.1.3.2.3 52 3-16 GeneralCommentIn some places (such as table 5-13 and section 5.2.1.3.2.3), therule is inconsistent with current & forthcoming EPA vapor intrusion guidances. This ruleneeds to be compliant with the two guidances coming out in March by EPA-OSWER & EPA-OUST.Hartman 5.2.1.1.1 45 21-23 If you set benchmark at 1 in 10,000 risklevel for cancer and HI=10 for non-cnacer, the background problem will go away.Hartman 5.2.1.1.2 45 32-36 You need to separate hydrocarbon VOCs from halogenated VOCs. Hydrocarbon VOCs bioattenuate which has ahuge effect on vapor migrationpotential.Hartman 5.2.1.1.2 46 13 Table 5-13,Row 6EPA vapor intrusion guidance only goes out to 100 feet, so to be consistent, this value needs to be 0, not 2Hartman 5.2.1.1.2.3 46 22 This should not be applied to hydrocarbon VOCs to be consistent with EPA vapor intrusion guidanceHartman 5.2.1.1.2.4 47 17 This approach is not valid for petroleum hydrocarbons as it does not accountfor bioattenuation. This approach should only be used for VOCs that do notbioattenuate.Hartman 5.2.1.3.2 51 29 Table 5-20 10-6 risk is far too low abenchmark. A more appropriate one for the HRS would be 10-4.Hartman 5.2.1.3.2 51 29 Table 5-20 A HI of 1 is too low a benchmark.A HI of 10 would be more appropriate as a benchmark for the HRSHartman 5.2.1.3.2.3 52 6-910 times is too low for subslab samples for this ranking. 50x is more appropriate. For crawlspaces, EPA OSWER says there should be no multiplier (1x).This rule is inconsistent with EPA VI guidance.Hartman 5.2.1.3.2.3 52 13 Thisfactor should be zero, not 0.1.Johnson 1Overall, the structure of this sectionseems to be based more on conventional wisdom(and common pathway misconceptions) than on the latestunderstanding gained from theory/modeling and critically-reviewed empirical observations.For example field data and modeling show that the single most significant influence on vapor intrusion impacts is whether or not a chemical is aerobicaForexample,fielddataandmodelingshowthatthesingle-mostsignificantinfluenceonvaporintrusionimpactsiswhetherornotachemicalisaerobicallybiodegradable, and that is not considered here.In addition, for chemicals that do not significantly biodegrade during vapor transport (i.e.,chlorinated solvents), the potential significance of vapor intrusionimpacts is primarily related to the quantity {(C Deff/L AB)/(QBCtarget)}, where C is the source concentration, Deffis the overall effective vapor diffusioncoefficient, L is the depth to the concentration C, ABand EBare the building footprint and exchange rate, and Ctargetis the target concentration for adverseimpacts. Of these quantities, the ones that might vary most from site to site and have the greatest influence on the potentialfor adverse impacts are theratios (C/Ctarget) and (Deff/L). The first is a measure of how strong the source is, while the second is a measure of the overall resistance to transportthrough the soil. The relative interplay between these quantities,the strength of the source,and the realistic sensitivity of(Deff/L) to depth and soil type arenot reflected in the proposed approach.The proposed approach could be replaced by a simpler one based on only two primary factors: one derived from (C/Ctarget) ratios and one from a soil typevs. depth table. There could also be a modifying factor for chemical degradability that would be based on (total of all biodegradableconcentrations/oxygen content in air and depth).Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionJohnson1.aWith respect to Table 5-12 (structure containment), I am not aware of definitive studies or significantanecdotal experiences that support the inclusion ofItems 4, 5, or 7. USEPA’s empirical database does not show a clear dependence on foundation construction (Item 4) and I am notaware of any definitivevalidation studies of the performance of passive systems (Items5 and 7). It is also not clear that Item 3 is needed either, especially given its value andthe reality that it is not feasible toidentify all intrusion points to buildings.Item 1 should include evidence of intrusionof hazardous contaminants (not justnon-hazardous contaminants). This table could probably be reduced to three items (currentItem 1 combined with Item 2, a combined Item 6 and Item 8,Item 9)Johnson1.bThere are ambiguities and potential issueswith application of Table 5-13 (depth tocontamination) and its associated discussion. In particular, it is notclear if the authors intended for contaminant concentrations to be below background ordetection levels for all distances lessthan this depth, or if it issimply the depth to the closest detection above background or detection levels? Theseare two very different concepts and havedifferent implications foruse in a scoring system like this.For example, if the authors intended contaminant concentrations to be below backgroundor detection levels for all distances between the foundation andthis depth, then Table 5-13 islikely overly conservative.On the other hand, if the depth to be used is the depth tothe closest detection above background or detection levels (independent as to whether or notthere are non-detect/background-level samples until that pointis encountered), then the tablemight not be sufficiently protective. For many sites, theremay only be groundwater data available, and so people will be using depth to groundwater with Table 5-13. The vapor intrusionimpact dependence ondepth to groundwater has not been shown throughfield data or modeling to be as significant as suggested by this table (e.g., modeling would show that atmost intrusion rates would be 10X less for a 200 ft depth than for a 20 ft depth for comparable groundwater concentrations and soils and empirical datamostintrusionrateswouldbe10Xlessfora200ftdepththanfora20ftdepthforcomparablegroundwaterconcentrationsandsoils,andempiricaldatashow little dependence on depth for the range of depthsrepresented in the empirical data set).The following revisions are suggested:1) Clarify the meaning of“depth to contamination”.2) If contaminant concentrations aresupposed to be below background or detection levels for all distances less than this depth (unlikely to be verifiedwith typical data used for ranking), then only two or three depth categories are justified and the value should be 0 for all depths greater than about 10 or20 ft.3) If it is the depth to the closestdetection above background or detection levels, then Depth to Contamination Assigned Values should not decline assignificantly with depth as happens in Table 5-13. It is justified to have a high value for cases with liquid intrusion or very shallow depths to groundwater,but depths to about 100 ft (most sites) should probably all have about the same valueand depths greater than 100 ft (few sites) should probably havevalues that are within 50% of the <100 ft values. This is inpart because there is a second important dimension not consideredhere in the factors –contaminant concentration. For example, a groundwater plume with a 20 ug/L concentration at 10 ft depth poses the same risk asa groundwater plumewith a 200 ug/L concentration at a 100 ft depth and a groundwaterplume with a 400 ug/L concentration at a 200 ft depth (all other factors being equal,and a non-biodegradable chemical).Johnson1.cThe vertical migration factor should be presented as being related to “soil type” and not effective porosity/permeability as these quantities are irrelevant tothe vapor intrusion pathway and only soil descriptions are used in Table 5-14 anyway.Categories 2 and 3 in Table 5-14 should be adjusted so that “silty loams; loesses; silty clays; sediments that are predominantly silts; moderatelypermeable till (fine-grained, unconsolidated till, or compact till with some fractures)” should be included in Table 2. EPA’sown modeling in its pathwayassessment guidance document (as well as other publications) and empirical data show little difference in behavior across thisrange of soil types.Depth creeps in as an overly-sensitive modifying factor in Table 5-15,compounding its use already in Table 5-13.Johnson 2It is suggested that this be eliminated as a factor in assessing the relative risk of vaporintrusion, as hazardous waste quantity has little relevance to vaporintrusion impacts, except to the extent that it mightimpact the longevity of thecontaminant vapor source.The proposed approach makes little sense and isnot technically defensible. The mass ofcontaminant in the residence is irrelevant for this pathway;instead it is the duration of time that the vapor source willproduce vapor concentrations of significance that is the relevantquantity. That in turn is relatedto source zone longevity (under natural or remediation conditions) and groundwater migration rates for dissolved plume sources.That is likely to be avery long time – probably decades for most sites evaluated by thisprocess, unless source removal and or control are going to reduce the time frame toless than a decade.Source concentrations should be included somewhere in the analysis as discussed above.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionJohnson3It should be recognized that thisapproach is predicated on two assumptions, both of which have weaknesses:1) It is assumed that areas of subsurface contamination have a 10X lower relativepotential for impact than areas of observed contamination, and2) Sub-slab soil gas samples are reliable indicators of vapor intrusion.With respect to (1), the preamble document contains the paragraph:“When an observed exposure has not been established, the EPA is proposing to evaluate the potential for exposure within structures located in the ASCwithin the subsurface intrusion component.Given that contamination within an ASC is documented as present below these structures, there is a potentialthat intrusion and exposure to the intrusion has occurred but that sampling has notbeen performed at the time the exposure wastaking place. Asexplained in sectionXXXX of the Proposal TSD, the factors affecting when intrusion will occur andthe rate of subsurface intrusion are extremely time-,site- and climatic-specific. Sampling maynot have been performed in these structures, or, even if performed during the limitedtime period of a siteinspection, the sampling may have been duringconditions that the intrusion was not occurring or occurring at levels not detectable or differentiable frombackground sources of the contaminant. Siteinspections are conducted overa limited period (usually1 to 3 days). Therefore itis important that thepotential for exposure be included as a consideration when evaluating subsurface intrusion threats.”This paragraph reasonably captures the current state of the practice – namely thatconventional point in time and point in space sampling (e.g., Summacanisters) has been shown to be inadequate for confidently assessing the presence or absence of vaporintrusion. In addition,empirical data have shownunacceptable and highly variable indoor air impacts at chlorinated solvent sites with groundwater concentrations as low as 10 ug/L, with no cleardependence on groundwater concentration, soil type,or depth. Thus, the reality is thatwe are unable to confidently identifya priori whether homes areexpected to be impacted, and which homes are likely tobe the most impacted above a dissolved groundwater plume.This proposed approach seems to ignore this. There is no basis for assigning lower risksto areas of subsurface contaminationhaving similar subsurfaceconditions as nearby areas ofobserved impacts simply becauseimpacts have not been observed.It is arguably more appropriateto assume that thepotential for exposure is the same in all areas having similar conditions, unless there has beenextensive data collection to prove otherwise. The otherfactors discussed above already reflect differencesin potential for impacts based on soil type and depth.Johnson 3 (con't) USEPA’s database (raw data – not the alpha factor analysis) should be reviewed carefully in dealing with the issue of relative risk of observed areas ofexposure vs. areas of subsurfacecontamination. For example, the figure below is from this database, and to it has been addedlines and text by P.C.Johnson (2011, presentations) to point outthat indoor air concentrations of concern have been observed across the full concentration range of interest forchlorinated solvent sites:[See graph included in pdf version of response to charge questions]With respect to (2), the approach ignoresthe debate and recent technical advances regarding the utility of sub-slab soil gas samples for pathwayassessment. It has been shown at a field study site in Utah thatindoor air sources can cause sub-slab contaminant vapor plumes; thus, the nearly 1:1correlation between indoor air and sub-slab soilgas detections is not validation thatsub-slab samples are good indicators ofvapor intrusion as statedabove(as 1:1 correlation would occur with indoor sources as well).)There are also field study results showing temporal and spatial variability in sub-slab soil gas samples and experience that sub-slab sampling may noteven have been done for pathway assessment by the time that HRS calculations are being done.Johnson 4It is not clear why possible exposures in the lowest floors (closest to the vapor source) would ever be discounted? Otherwise,I have no comments on thisapproach as I have little experience with impacts in multi-story buildings to draw from at this point in time. It is difficultto imagine many scenarios wherethis issue will be a determining factor in HRS calculations.Johnson 5This seems to be a comparison of applesand oranges (indoor vapor inhalation vs. outdoor soil exposure), so assuming some fixedcorrelation betweenthe two would be inappropriate.It might be reasonable to assume that worker inhalation riskswould be less than those of residents in homes in similar conditions because of differencesin exposure durations. The type of work might affect both the building ventilation and worker breathing rates, so indoor concentration rates might be lowerand inhalation higher in more industrial settings vs. office and residential settings.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionJohnson1.1437Need to add a manmade example to the list – perhaps “utility conduit”?Johnson1.1437-38How is this different from “preferentialsubsurface intrusion pathways” given below?Johnson2.1108[Referring to "Soil Exposure andSubsurface Intrusion"]: Might be better tomake this the fourth bullet item so that the three “migration” pathways are listedsequentially.Johnson2.11017It’s not clear that this istrue if you define the subsurface intrusion pathway to include both vapor and liquidintrusion as the threat from the former is vaporinhalation while the threat from the latter might include direct contact as well as inhalation.Subsurface intrusion threats might also include explosions.Johnson2.1.31040[Referring to "...or observed exposure..."]: Should be either “and any verified areas of exposure” or “and areas of observed exposure”. “or” seems notappropriate here as you will always have areas of observed contamination.Areas of observed contamination are defined in §2.3, the terminology in §5.2 is“area of subsurface contamination”Johnson2.1.31216As “migration pathways” isused as terminology throughout the document,it is suggested that the term be included in the Definitions section.Johnson2.21232[Referring to "...areas ofobservedcontamination or observed exposure..."]: Should be “subsurface” tobe consistent with terminology for the subsurfaceintrusion pathway?Johnson2 21232[Referring to"areas of observed contaminationorobserved exposure"]: Should be“and areas of observed exposure”Johnson.[Referringto...areasofobservedcontaminationobservedexposure...]:Shouldbeandareasofobservedexposure ?Johnson2.21233[Referring to "...areas ofobservedcontamination or observed exposure..."]:Should be “subsurface” to beconsistent with terminology for the subsurfaceintrusion pathway?Johnson2.21233“areas of observed contamination” not a term defined in Definitions – “areas of subsurfacecontamination” is defined.Johnson2.21233[Referring to "...areas of observed contaminationorobserved exposure..."]:Should be “and areas of observed exposure”?Johnson2.2.11239I suspect that people will getconfused by “migration pathway” terminology – so you might consider being more explicit on the forms like Table 2-2 andinclude additional headings that clearly groupair, groundwater, and surface water togetheras migration pathways separate fromthe subsurface intrusionpathway.Johnson2.2.11241[Referring to "...areas ofobservedcontamination or observed exposure..."]:Should be “areas of subsurface contamination” to be consistent withterminology for the subsurface intrusion pathway?Johnson2.2.11245Table 2-2 Should this alsoinclude area of observed exposure? Also, it’s not clear what should be entered in the boxes in table 2-2?Johnson2.2.21312[Regarding "area of observed contamination"]: Needs to be defined in Definitions.Johnson2.2.21318[Regarding "observed contamination"]: See comment above concerning “observed contamination”Johnson2.2.31431[Regarding "observed contamination"]: This terminology is not used in §5.2Johnson2.3151Table 2-3 Should be “Observed Release and Observed Contamination Criteria”? to be consistent with lines 37-38?Johnson2.3151Table 2-3[bulleted text]I’m not sure if these criteria are usefulfor the vapor intrusion pathway. First, it isnot clear what kinds of samples this applies to (indoor air, soil gas,groundwater?) and second it does not include consideration of indoor air sources. Finally, for vapor intrusion indoor air datasets, the SQL, backgroundlevel, target acceptable breathing concentrations, and indoor air concentrations are often with about 10X of each other.You might consider limiting the analysisto only groundwater and soil gas data (and notindoor air data) for this part of theevaluation. That will eliminatesome of my concerns.What do you do when you have conflicting linesof evidence (e.g., indications of groundwater impacts but no soil gas detections?)Johnson 2.4.1.1 15 30[Referring to "ainhalation risk"]: [Should "a" be changed to]: “an”?Johnson 2.4.1.2 18 34 [Referring to the word "or"]: “and” more appropriate here?Johnson2.4.1.2 1834[Referring to "underlying"]: “from substances underlying”?Johnson2.4.21838[Referring to "...area of observed contamination or observed exposure..."]: Should be “area of observed contamination, subsurface contamination, orobserved exposure”?Johnson2.4.21851[Referring to "observed contamination"]: Should be “subsurface contamination” here?Johnson2.4.21851[Referring to "...observed contamination or observed exposure..."]: Should be “area ofobserved contamination, subsurface contamination, or observedexposure”?Johnson2.4.21852Do we have a criterion for “observed exposure”?Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionJohnson2.4.2 18-19 50-53, 1This sentence makesmy head hurt real bad [smiley face] Might be best to break it up into bulleted items to improve clarity... Also, make sure that theterminology is being used correctly.As they are introduced originally in the text, “Observed contamination”seems to refer to a determination as to whether or notchemicals are present atlevels of significance, while areas of subsurface contamination and exposure are delineated areas. Thus, use of the term “areaof observedcontamination” confuses me...Johnson2.4.2.1 1913-14What do you do in the situation where many homes overliea single large dissolved chlorinated plume?Johnson2.4.2.1.1 203-4Why only the area of observed exposure, given the caveats concerning the difficulty in identifying actualexposures for this pathway?Johnson2.4.2.1.1 206[Regarding "or area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, orobserved exposure”?Johnson2.4.2.1.1 208[Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson2.4.2.1.1 2010[Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson2.4.2.1.2 211-2[Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson24212214[Regarding"area of observed contaminator observed exposure"Should be“area of observed contamination subsurcontamination or observedJohnson...1.2[Regardingareaofobservedcontaminationorobservedexposure ]:Shouldbeareaofobservedcontamination,subsurfacecontamination,orobservedexposure”?Johnson 2.4.2.1.2 21 15-16 Why only the area ofobserved exposure, given the caveats concerning the difficulty in identifying actual exposures for this pathway?Johnson 2.4.2.1.3 21 33 [Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson 2.4.2.1.3 21 43 Why only the area of observed exposure, given the caveats concerning the difficulty in identifying actual exposures for this pathway?Johnson 2.4.2.1.3 21 45 [Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson 2.4.2.1.3 21 48 [Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson 2.4.2.1.4 22 1-2 [Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson 2.4.2.1.4 22 11 Why only the area of observed exposure, given the caveats concerning the difficulty in identifying actual exposures for this pathway?Johnson 2.4.2.1.5 22 15 [Regarding "area of observed contamination or observed exposure"]: Should be “area of observed contamination, subsurface contamination, or observedexposure”?Johnson 2.4.2.2 23 12 [Regarding "observed contamination"]: “observed” or “subsurface” contamination?Johnson 2.4.2.2 23 14 [Regarding "observed contamination"]: “observed” or “subsurface” contamination?Johnson 2.4.2.2 23 18 Why only the area of observed exposure, given the caveats concerning the difficulty in identifying actual exposures for this pathway?Johnson 2.4.2.2 23 20 Why only the area of observed exposure, given the caveats concerning the difficulty in identifying actual exposures for this pathway?Johnson 2.4.2.2 23 36-38 This assumes that sub-slab samples are reliable indicators ofvapor intrusion potential, and there is debate concerning that given their potential to beinfluenced by indoor air sources and the potential for significant spatial heterogeneity.Johnson5.2.04431-37What do you do ifyou have conflicting lines ofevidence(e.g., groundwater impact but no soil gas impact)?Conflicting lines ofevidence is a commoncondition for vapor intrusion assessments.Johnson5.2.04439-40You should probably also mention that unacceptable indoor air impacts have beenobserved at sites with fine-grained soils and dissolved concentrationsin the 10’s of ug/L range to help put this issue in perspective.Johnson5.2.1.1 451Empirical and modeling datafor indoor concentrations at chlorinated solvent sites do not show significant orclear dependences on structure type, depth,soil type, or groundwater concentration, etc.. (the factors considered here). They most significant factor seems to be contaminant type. This iscontradictory to the implicit underlying assumptions that this section is based on.Johnson5.2.1.1.1 4521-23Not clear why this is a bulletitem under a statement specific to indoor air samples?Johnson5.2.1.1.2 4532-33Need some statement here explaining that the vapor intrusion pathway is difficult to observe using conventional measurements,and therefore thepotential must be looked at closely and weighted higher than for a pathway where it is easier to confidently document non-exposure. There is some goodtext in the Preamble on this topic.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionJohnson5.2.1.1.2.1 4537-39I’m not familiar with any studies showing the effectiveness of passive systems, and am therefore uncomfortable with the assumption that they reduce thepotential for exposure (Item 5)Also EPA’s empirical database does not show any significant impact of foundation type on indoor impacts, so there is little basis for Item 4.Johnson5.2.1.1.2.2 462-3What if youonly have groundwater data and no soil gas data? This would lead to deeper depths.Johnson5.2.1.1.2.2 4613 Table 5-13 This tableassumes a significant reduction in exposure potential in moving to >20 ft BGS. Formany sites, there may only be groundwater data available,and so people will be using depth to groundwater with Table 5-13. The vapor intrusion impact dependence on depth to groundwater has not been shownto be as significant as suggested by this table in either empirical data ormodeling. Depth probably should probably not evenbe a significant modifyingfactor for this pathway, unless it is required that both groundwater andsoil gas data be collected.Suggest changing to the following:- structures with intrusion of contaminated liquids probably should be prioritized above others that do not.- Depths to at least about 50 ft should probably all be assigned the same valueJohnson5.2.1.1.2.3 4626[Regarding "effective porosity/permeability"]: Suggest removing this terminology and just refer to “soiltype” in this section. There is no need to mentioneffective porosity or permeability when discussing vaporintrusion, as these are irrelevant quantities.Johnson521123474Table 5-See comment above [[Regarding"effective porosity/permeability"Suggest removing this terminology and just refer to“soil type”in this section There isJohnson..1.1.2.3Table5 14Seecommentabove[[Regardingeffectiveporosity/permeability ]:Suggestremovingthisterminologyandjustrefertosoiltypeinthissection.Thereisno need to mention effective porosity or permeability when discussing vapor intrusion, as theseare irrelevant quantities.]Johnson5.2.1.1.2.3 474Table 5-14 [Regarding "Assigned Porosity/Permeability Value"]: See comment above. Just call this “soil type factor” or something simple like that.Johnson5.2.1.1.2.3 474Table 5-14 [Regarding "...silty loams; loesses; silty clays; sediments that are predominantly silts; moderately permeable till (fine-grained, unconsolidated till, orcompact till with some fractures)..."]: These materials shouldbe in the second category – the empirical data and modeling do notsupport any significantdifference in vapor intrusion impacts for these materials in comparison with sandy silts, etc.Johnson5.2.1.1.2.3 476Table 5-15 [Regarding "Lowest Porosity"]: Need to change...Johnson5.2.1.1.2.4 489Table 5-16 This approachassumes that there are no combinations of low volatility and high toxicity of concern. Has that been verified (e.g., pesticides, PNA’s, etc.)?Johnson5.2.1.1.2.4 4814 Table 5-18 [Regarding "Average of Vapor Migration Potential Values for Three Hazardous Substances"]: ?? Why do this?Johnson5.2.1.1.2.5 4818-19[Regarding "factor value for containment"]: What is this?Is it the structure containment value?Johnson5.2.1.2.2 4910[Regarding "Hazardous waste quantity"]: It is not clear that thisquantity has any relevance to assessing the significance or relative risk of this pathway?Why is it even considered?Johnson5.2.1.2.2 4937Why onlyareas of observed exposure?Johnson5.2.1.2.2 5018-20See comments aboveconcerning the use of sub-slab samples.Johnson5.2.1.3.2.3 526-7See comments aboveconcerning sub-slab and crawlspace samples.Johnson5.2.1.3.2.3 5210-13This assumes a higher confidence in sub-slabsamples than in groundwater samples.Larsen1.aPotential for Exposure EquationI agree generally with the mathematical set up of the equation (2a*(2b+2c+2d) and the decision to make the potential for exposure a product (in themathematical sense) of a building’s characteristics and the subsurface conditions that lay beneath it. It mimics the two compartment model that manyprofessionals and researchers conceptualize tvapor intrusion pathway to be Furthermore I believe it accurately replicates the“breaking”of theprofessionalsandresearchersconceptualizethevaporintrusionpathwaytobe.Furthermore,Ibelieveitaccuratelyreplicatesthebreakingpathway by assigning a value of 0 to structures thatemploy demonstrated effective vapor control measures.Overall, the term for the structure (a) ranges from 0-10 while the subsurface term (the sum of b+c+d) ranges from 1-50. Ideallythe subsurface term shouldrange as low as zero to reflect the absence of vapor intrusion risks associatedwith high molecular weight semi-volatile compounds like cPAHs, PCBs,and most pesticides. Thus, either term could have a zero value and the exposure pathway would then be considered broken or incomplete under twoconditions: 1) in cases where a demonstrated effective vapor control technology is used, and 2) when a contaminant has sufficiently low volatility.Mathematically, this could be accomplished by multiplying the Depth to Contamination (b) and Vertical Migration (c) terms by the Vapor MigrationPotential (d) term. Thus a zero Vapor Migration Potential value would yield a zero for the entire Potential for Exposure factor. If the equation is changedin this way, the range in values for the Depth to Contamination and Vertical Migration terms would likely have to be adjusted so that Potential for Exposureresults fall into the intended range of values (0-500).Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen1.aTable 5-12Table 5-12 Structure ContainmentI suggest revisions to Table 5-12 with respect to the number of building types distinguished, their description, and their value assignments.• There does not appear to be a category that describes maybe the commonly encountered type of residence: a slab-on-grade constructed home with noapparent open preferential pathways or vapor migration barrier system. This is a significant omission that I believe will leadto confusion in categorizingstructures. On the scale of 1-10 that isused for this factor I would assign this category of building a value of 9. It is vulnerable to vapor intrusion, but it isnot the most vulnerable of residential structures.• Homes that are underlain by a combination of basement and crawl space, and which do nothave any form of vapor mitigation system, should bedescribed as such and placed in Category 2. This is a commontype of residential construction and it would be an omission to leave it out of Table 5-12.With this type of building there usually is a 4-5 ft high stem wall that separates the crawl space from the basement and generally there is no seal or a verypoor seal between the crawl space and basementareas. This allows vapors to freelymigrate into the basement and living spacesmaking these homessome of the most sensitive and vulnerable with respect to vapor intrusion. This type of structure should be assigned a valueof 10 in Table 5-12.• In my experience, residences that are completely underlain byvented crawl spaces generally have fairly small attenuation factors and their vulnerabilityto vapor intrusion is considerably less than other building types. This was observed at a chlorinated solvent release at theEugene Rail Yards site inEugene, Oregon. At this site, crawl space concentration showed a broad range of attenuation factors and a poor correlation to soil gas values. Itappeared crawl space concentrations were most influenced by background and insignificantly by soil gas that spanned a range of PCE concentrations.Based on my experience I would assign a value of 6 rather than 8to this type of construction. However, I acknowledge that nationally there may beregional/climatic differences that affect the degree of communication between the crawl space and the overlying building and justify the value of 8.• Evidence of biogas, inert gases. Is this referring to methane and radon? Typically this type of information is not availablefor relatively short inspections.Larsen1.bAt the depths beyond the 0-10 ft range presented in Table 5-13 chemical diffusion isgenerally considered to be the dominant transport mechanism.Diffusion and diffusive flux is typically described using Fick’sLaw J= -D(dc/dz). Using Fick’s Law and assuming 100 ug/m3 atthe source and zero inindoor air, concentration gradients as afunction of depth are plotted below.[See Graph in PDF of Henning's Response to Charge Questions]Using this approach and assuming a Depth to Contamination value of10 for a source 10 ft below the occupied base of a structure, 20 ft would then havea value of 5, 50 feet would have a value of 2, 100 ft a value of1 and 150 ft of 0.66. Since this term is evaluating the strength of diffusive flux in thesubsurface and not attempting to consider geologic heterogeneity, the values should bebased on Fick’s Law of diffusion which has been empiricallydemonstrated to be accurate in numerous column tests of porous media; this is unless there is sufficient empirical field data that supports the numericalassignments in Table 5-13.Considering Depth to Groundwater Contamination andDepth to Soil Vapor Contamination EquivalentlyAn important concern in the assignment ofDepth to Contamination values under section 5.2.11.2.2 is the approach treats groundwater and soil gas asequivalent media and at any given site theredepths are presumably comparable. However,it isn’t an either or situation, if there is a groundwater plumeof contamination at the water table, there will be corresponding soil gas contamination above it and by definition the soil gas will always be shallower thanthe groundwater contamination. Depending on where the soil gas measurement is taken itcould be 20, 30, 50 ft or more shallower than the depth thegroundwater contamination is measured at. Thus, the depth to contamination that is entered into this table may in large part be a consequence of whichmedia was sampled and not the actual site conditions.I ran one of our bigger vapor intrusion sites (Tarr Oil, Portland, OR) through the Potential for Exposure calculation and it scored a 380 based on the initialgroundwater data, and a 500 based on soil gas data. The location of the measurement alsoaffects assignment of the Vapor Migration Potential value.The depth of measurement and choice of media to sample potentiallyintroduces a bias that shouldideally be eliminated from thecalculations.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen1.cAssignment of Vertical Migration Factor ValuesVertical migration values for soils assigned a porosity/permeability value of 4 (clays, low permeability till, unfractured igneous rocks etc.) appear to beexcessively high when compared to the values of other soils and thicknesses in Table 5-15 and relative to values assigned to the Depth to Contaminationfactor. True clays and unfractured igneous rocks have extremely low effective porosities and if they have any appreciable thickness should act as avirtually complete barrier to vapor transport. The only exception would be if the clays were or had been desiccated leaving fractures for preferential flow.It is difficult to say the 0-5 ft thickness value of 15 forsoils assigned a porosity/permeability value of 4 is disproportionately high given the thickness rangesdown to zero. However, I suggest revising the value for the 5-10 ft thickness to 8 rather 12, and the 10-20 ft thickness range 6 rather than 9 and the 20-50 ft range to 3 rather than 6 and the 50-100ft and 100-150 ft ranges both should be 1. Icannot think of a more restrictivebarrier to vapor transport than50-100 ft of true clay.The values in Table 5-15 applied to soils assigned a permeability/porosity value of 1-3 appear appropriate.Although not discussed, effective porosity for gas transport (diffusion rates through water-filled pore spaces are generally 100,000x or more lower thanthrough air-filled) is highly sensitive to moisture content in the soil and I assumethis consideration is embedded in the values of Table 5-15. Finer-grainedsoils typically retain a higher moisture content that further reduces effective porosity. This degree to which soils are saturated is largely a consequence ofannual precipitation rates and their seasonal distribution. Therefore, for identical soils it’s anticipated that there would beregional differences in thevertical migration factor. Ideally the moisture content factor would be considered in the scoring, however, there may be insufficient information toconfidently develop values.Larsen 2I disagree with the proposed approach to calculating hazardous waste quantities for thesubsurface intrusion component. Compared to soil and water, airis a much less dense medium and as a consequence, for equivalent risk levels between various media, it typically contains muchless contaminant mass.Essentially airborne contaminantscan generate equivalent human health risks to thoseresulting from contact with other media,although with far lessmass. For example, the State of Oregon assumes benzo(k)anthene has an oral slope factor of 0.073 and has calculated a residential soil screening levelof 6.2 mg/kg (equating to 1x10-6 risk). Assuming a 5000 ft2 property that is 70% land 30% impervious surface, a 1 foot thick layer of soil contaminated upto the screening level would contain approximately 1,190 grams of benzo(k)fluoranthene. In comparison, a 1300 ft2 residence with vinyl chloride(inhalation slope factor of 0.031) contamination at a concentration 0.14 ug/m3 (equivalent to 1x10-6 risk) has 0.000047 grams in the indoor air at any onetime. Assuming an air exchange rate of 6 exchanges/day, approximately 3.1 grams would have moved through the home over a 30 year period of time.Assuming an identical toxicity and slope factor to that of benzo(k)fluoranthene, the mass of vinyl chloride in the air over the 30 year period is 6.3 gramsfor the equivalent risk. Humans contact and take up air contaminants much more efficiently than contaminants in water or soil, therefore, it requires farless mass for equivalent risk.Using Table 2-6 (pg. 22) and the methods outlined in 5.2.1.2.2 to assign a Hazardous Waste Quantity Factor value, it is likelymost vapor intrusion siteswould get a quantity of 1 unless an exposure is documented then itdefaults to 100. It appears very unlikely any VI site wouldhave hazardous quantityfactor larger than 100. This results in relatively low Waste Characteristic Factor values compared to what can calculated forother media and pathways.In this respect it appears to underestimate the risk of the subsurface intrusion pathway relative to others.Suggested Alternative Proposed HRS Method of Estimating Hazardous Waste QuantityQuantify and include contaminant sources in the subsurface in addition to the contamination found within the buildings. Thesesources constantly feedthe contamination within the buildings and so could be legitimately included in the inventory of waste quantities. For this particular factor, the changewould make the magnitude/mass of sources of vapor intrusmore comparable to those contaminating other mediawouldmakethemagnitude/massofsourcesofvaporintrusionmorecomparabletothosecontaminatingothermedia.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen3An obvious answer to the Charge Question#3 is: yes, in general occupants of buildings where sub-slab concentrations exceed 10xa health-basedbenchmark are at higher risk relative to occupants ofbuildings with sub-slab concentrations that are less than this value. However,the scheme for weighting individual targets/receptors is crude in the ASC,does not appear consistent with the results of EPA’s compilation of paired sub-slab and indoordata, and potentially underestimates population risks.As described in sectionsxxxx of the draft HRS rule revisions, for targets/receptors occupying buildings over an ASCand where subslab contaminantconcentrations exceed 10x the benchmark screening level should assigned a weighting of 0.75. The explanation given is that thereview of the compiledpaired data indicate 80% of the time a subslab concentration exceeds 10xits respective health based benchmark, the contaminant is detected in indoorair.• Why wasn’t a value of 0.8 used instead 0.75 since thecorrelation described above was observed 80% of the time?• 0.75 is used in all where a subslab VOC concentration greater than 10x its corresponding health-basedbenchmark has been observed within the ASC.However, subslab VOC concentrations at many sites are routinely observed at levels from 100-100,000 times their corresponding benchmarks. Yet in theproposed HRS scheme for weighting targets, irrespective of the concentration observed, any time itexceeds 10x the benchmark a value of 0.75 is used.Using a single value (such as 0.75) may bereasonable for weighting receptors when subslab levels are just1-2 orders of magnitude above benchmarkvalues, and indoor concentrations are likely detectable but below benchmark values. However, as subslab contaminant levels increase, eventually aconcentration threshold is crossed where the results of EPAdata compilation indicate the probability of exceeding a benchmarkvalue in indoor air is veryhigh. For these cases assigning a weighting factor that is closer to10 is more appropriate.Larsen 3 (con't)The proposed target weighting approach may introduce a low bias to population risks, particularly at sites wherethe primary medium sampled is subslaband not indoor air. soil gas and not• It is not clear from the rule revisionwhether the appropriate weighting for targets within the ASC is based on the maximum observed subslabconcentration or whether some form of average value is considered (i.e. arithmetic mean, UCL, etc.) My recommendation, since this is a screeningprocess, would be to use the maximum subslab concentration observed, and that this expectation should be specified in the ruleif it isn’t already.• The EPA database on paired subslab and indoor air data has been reviewed by many states and individual practitioners. Statistics have beenperformed on both filtered and unfiltered data. The filtering was done in an effortto eliminate the influence of ambient background concentration oncalculated attenuation factors. EPA has recognized the need to perform the data filtering to remove outlier attenuation rates.A strategy that Oregon DEQused in an attempt to separate out backgroundinfluences was to only consider data fromsites with strong sources, for examplessites with subslabconcentrations greater than 1000 ug/m3.The results of the data analysis indicate unfiltered paired subslab-indoor air data had an average attenuation factor of 0.003and median value ofapproximately 0.002. An analysis of highly filtered similar todata by ODEQ produced an averageattenuation factor of 0.0007 and a median value of0.0002. Thus the statement that approximately half of the vapor intrusion sites hadan average attenuation factor of 0.1 is not supported by EPA previousanalysis of VI data.[See pdf of charge questionsresponse for three graphs]Larsen 3 (con't)RecommendationBased on: statistical analyses of the EPA Database and the recognition tit does not necessarily populated by the most sensitive structure types IBasedon:statisticalanalysesoftheEPADatabase,andtherecognitionthatitdoesnotnecessarilypopulatedbythemostsensitivestructuretypes,Irecommend that within defined ASCs assign a target weight factor of:• 0.1 to occupants of buildings withsubslab contaminant concentrations less than 50x the health-based benchmark value.• 1 to occupants of buildings with subslab contaminant concentrations between 50x-500x the health-based benchmark value.• 10 to occupants of buildings with subslab contaminant concentrations greater than 500x thehealth-based benchmark valueLarsen 4 Figue 3 [Referring to graphic of second building from left]: Inthis contaminant distribution, I would assume all basement residences are Level I due to error anduncertainty from temporal variability of indoor air qualityLarsen 4 Figure 3 [Referring to graphic of third building from left]: In the above scenario, if level I and level II exposures are observed on the first floor I would assign level Ivalues to the basement dwellings also. They are overwhelming the most sensitive locationsand having a reverse gradient scenario as depicted, wherehigher concentrations overlie lower concentrations would be very unusual for a VI site. A more likely explanation for this type of observed distributionwould be simply being temporal variability in indoor air levels.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen4Figure 3 [Referring to graphic of far right building]: I would weight the occupants of the first floor based on the concentration observed in the basement. Theseresidences and their occupants may be under weighted just because of the absence of directobservations – to remedy this use the EPA database tomake educated inferences of exposure levelsLarsen4Regarding the Calculation of Waste QuantitySee comments and responses to Charge Question #2Regarding Assumptions and Weighting of Occupants/Targets in Multi-Family ResidencesSome comments are made directly on the Figure 3 – see boxed text. Aside from those suggestedmodifications, the general schemelooks appropriate.Regarding the Weighting of Population Targets in AOEIn my opinion the weighting is disproportionately influenced by data type – specifically the difference in weighting directly observed impacts as comparedto inferred impacts based on subslab sampling. Whereas an individual or population directly observed (through indoor air sampling) to be exposed tolevels above the health-based benchmarkis indoor exposure directly observed to be over a benchmark is assignedThe weighting of targets/receptors exposed to Level 1 contamination 10x higher thanthose exposed to LevelII concentrations bya factor of 10, coupledwith the recognized temporal variability in indoor air concentrations (See Paul Johnson’s recent work at Hill Air Force Base, Arizona) could producesignificant swings in the population score that are more artifacts of when the sampling occurredthan true differences in the magnitude of the averageVOC exposure. The concern regarding accurately characterizing indoor exposure levels is particularly relevant if site inspections are conducted andindoor air concentrations measured within a short 2-day periodindoorairconcentrationsmeasured,withinashort2 3dayperiod.Potential Ways to Mitigate Errors and UncertaintiesTwo ways to mitigate this uncertainty andpotential error is to characterize exposure levels using ambient air sampling methods that accommodate longsampling periods, or alternatively increase the number of (shorter period) air samples that target meteorological conditions particularly conducive to vaporintrusion. In short, use sampling technologies are approaches that provide better representations oflong term exposure levels.A different approach would be to apply a scheme that has more than two designations for confirmedexposure levels. Perhaps thevalue 1 fordetected/observed exposures thatare <0.5x the benchmark health value, a value of3 for values 0.5 -1.0 x the benchmark value,and 10 for thoseoccupying buildings with exposures greater than the benchmark value.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen 4 (con't)Weighting of Population Targets in ASCIn the proposed approach for weighting target populations withinthe ASC it appears there isa disproportionate undervaluing ofsusbslab data relative toindoor data. Under the proposed scheme, subslab concentrations greater than 10x thehealth-based benchmark value would weightedwith a factor of0.75 (weighted slightly less than a level II exposure) irrespectiveof the specific concentration measured. EPA compiled a large database that providesopportunities for robust statistical analysesincluding the derivation of attenuationrate percentiles and confidence intervals. This information should beused to help appropriately weight targets where only subslab data is available. For example, using unfiltered statistics the 50th percentile attenuationfactor is 0.03, thus it can be concluded that if subslab levels exceed benchmarks bya factor of 33 or greater then there is 50% chance occupants arebeing exposed to levels above the corresponding health-based criteria and that the appropriate weighting is 10 rather than 0.75.In section 5.2.1.3.2.3, the proposed rule indicates subslab data and crawlspace data will be similarly evaluated and weighted.The implies the data typesare equivalent, however, EPA and others have generally assumed theattenuation factor between the crawl space and the residence interior should beassumed 1and thus is a reasonable surrogate for actual indoor air data. So, this would suggest detection of COCs below benchmark values in the crawlspace should be weighted under the proposed scheme at a value of 1 and that if concentration exceeds benchmark values in the crawl space theappropriate weighting would be 10.In general there appears to be a undervaluing ofsusbslab data, even when that is the only type of data available. However, susbslab data may be theprimary type of data available at a site and the population component of the scoring may be biasedlow as consequence. Thus,at any given site, thescored risk may be substantially lower if the primary data source is subslab measurements than compared to the same site if theprimary source of datawas indoor measurements.RecommendationUse EPAs database of paired subslab and indoor air data to performmore refined weighting of targets in an ASC. Ideally, the weighting would relate tothe probability a Level I or Level II exposure is occurring based on subslab data.Additional CommentThe example scenario described in the Charge Question #4 is highly unusual contamination found on5th floor consider tenants on4th and 6th floors.Under this scenario I would expect all floors beneath the 4th floor to be considered and actually most of them contaminated. Overall, it’s an unrealisticscenario and the actual proposed rule indicates all floors beneath the observed exposurewould be considered in the calculations, as they should be.Larsen5I agree with the proposed weighting for workers. Generally, workers do spend more time indoors and that this pathway is more likely to be complete.Larsen1.172It seems, the question of non-occupancy should consider how long a residence has been vacant. To indicate the probability it will be occupied again.Larsen1.1821Might consider discussing effective air-filled porosity since this is the actual porosity that counts.1.1831I would add a definition of crawl space type construction and crawl space sample.Larsen2.1.11027Equation I agree with the form of the equation and howvapor intrusion pathway was incorporated. It allows the soil exposure or VI component to drive risk. Theytypically will be different substancesdriving the two pathway components.Larsen2.4.1.1 1618Table 2-4 [Referring to "0.0001≤RfC < 0.006"]: Factor of 60 differenceLarsen2.4.1.11618Table 2-[Referring to"0 006≤RfC < 0 2"Factor of 33 difference2.4.1.1Table2 4[Referringto.RfC<0.2 ]:Factorof33differenceLarsen2.4.1.1 1618Table 2-4 [Referring to "0.2≤RfC < 2.0"]: Factor of 10 differenceLarsen2.4.1.1 1618Table 2-4 [Referring to "0"]: Changes in RFC are directly proportional to benchmark values and calculated risk. Yet the RFC does not increase consistently (orderof magnitude) the way the assigned values do. I do not seethe justification for abandoning the order of magnitude approach aswas previously used.Larsen2.4.1.2 1835Within large chlorinated solvent plumes, riskdrivers can change depending on location. Thus to capture truerisk you may not focus on only onesubstance. This should be accounted for in the general approach.Larsen2.4.2.2 2321As indicated in my responses to the charge questions,these calculations should consider the quantity of contaminant in the subsurface as well as inbuildings. This would make better comparisons to hazardous waste quantities in other media and also account for the uniquenessof the indoor airpathway with respect to waste quantity.Larsen5.2.1.1.2.1 4540 Table 5-12 [Referring to "Evidence of intrusion by biogas, inert gases or other non-hazardous substances, pollutants or contaminants"]: Does not represent acircumstance I typically come across orinformation that is not typically gathered.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLarsen5.2.1.1.2.1 4540 Table 5-12 [Referring to "Existence of maintained vapor migration barrier system but not addressing all preferential pathways"]: Typical home struction often fallssomewhere between No. 2 and No.3 – there should be one or morecategories added to represent fuller range of structures encountered.Larsen5.2.1.1.2.2 4611Treating subslab and water media as equivalent make work for overall predictions of VI. But depending onwhat media has been sampled, the same sitemay score differently based on whether soilgas or only groundwater data was collected. I scored the same site using both setsof data and the scoringbased on soil gas came out at 500, the samesite scored 380 based on groundwater data.Larsen5.2.1.1.2.2 4613 Table 5-13Last Row[Referring to ">150ft 0"]: These values should mirror predicted changes in diffusive flux as predicted by Ficks Law – one-dimensional application.Larsen5.2.1.1.2.3 4620Use the most sensitive structure.Larsen5.2.1.1.2.3 474Table 5-14 There is no consideration of moisture content and its affects on diffusive/advective flux. Thiswould likely be better captured inregional differences relatedto climate. However, it is an important factor that does not appear in the scheme at all.Larsen5.2.1.1.2.3 474Table 5-14 True clays are unusual and are very effective barriers.They seem overvalued in Table 5-15.Larsen5.2.1.1.2.4 4814 Table 5-18 I don’t understand why we average the transport potential of threesubstances then use only toxicity data from 1.Lofstrom/Klein 1There is no provision for significant volatile organic chemical (VOC)concentrations detected in soil and/or surficial groundwater but without structures.Alternative: Provide default structure properties.The vertical migration factor rankingconsiders certain geologic factors and identifies karst, lava tubes, open fractures (5.2.1.1.2.2) as features that wouldallow channelized flow. Manmade preferential pathways such as utility corridors and sewer lines should be included in the HRSassessment, if identifiedin the site inspection. Alternative: Expand the definitionof channelized flow to include most commonly encountered featuresand/or include thatexpanded list in the regulatory language (Perhapsas part of Table 5-15 Vertical Migration Factor Values).Lofstrom/Klein 2The hazardous waste quantity ranking is based onthe assumption that a structure or structures currently exist on the site being evaluated. If this is thecase at the site being evaluated, the approach seems appropriate. But it is difficult to imagine that the sampling necessary to carry this approach out canbe accomplished within a 1 -2 day site inspection. Soil gas/groundwater sampling should be done prior to indoor air sampling in order to identify thosesubstances to be analyzed for in indoor air (substances associated with subsurface contamination).However, the approach does not allow for the determination of the hazardous waste quantity in theabsence of structures but where significant hazardoussubstance (VOC) contamination exists in soil/groundwater where structures could or willbe constructed. Alternative: Providea simple approach forestimating indoor air concentrations from measured environmentalmedia concentrations (soil gas, groundwater) using default attenuation factors andparameters for a default structure. Provide default volume values (a default area value is provided (Table 5-19)). I could not find in the proposedregulations explicit direction on “where no home issubject to actual contamination”.Lofstrom/Klein 3This approach is consistentwith the California Department of Toxic Substances Control (DTSC) vapor intrusion guidance.Lofstrom/Klein 4This is a reasonably conservativeapproach. However, there is much uncertainty surrounding the stated assumptions. Therefore,there should be an indepth discussion of this approach in the proposal Technical Support Document with references to support it.Lofstrom/Klein 5Assuming a relative risk of three times greater for indoor workers vs. outdoor workers for volatile organic chemicals (VOCs) may be an underestimate,since indoor workers would be exposed to contaminated air in a limited volume over much of their work day; whereas, contamination in outdoor air is notconstrained in a limited space but is immediately diluted by atmospheric air. Otherdirect exposure pathways (incidental soilingestion; dermal contact)t ib t littl t t k /i t k b f th l til t f th h i l d di i i th b f i t it Thcontribute verylittleto uptake/intakebecause ofthe volatile nature ofthe chemicals underdiscussioninthe subsurfaceintrusion componen.eproposal Technical Support Document should discuss and provide support for any factor chosen to reflect the greater relative risk for indoor workers.Lofstrom/Klein 1.1 6 16 Definitions [The word 'agent']: Should be changedto ‘hazardous substance’ to be consistent with the language in the proposed regulations.Lofstrom/Klein 1.1 7 1 Definitions [The word 'was']: should be 'were'.Lofstrom/Klein 1.1 7 34 Definitions [The word 'toxicant']: Should be changed to ‘substance’or ‘hazardous substance’.Lofstrom/Klein 1.1 8 42 Definitions [The word'agent']: Change to ‘hazardous substance’.Lofstrom/Klein 1.1 9 7 Definitions [Regarding weight of evidence classification system] This classification scheme is no longer being used by the EPALofstrom/Klein5.2.14441There should be a bullet addressing area ofsubsurface contamination notcontaining a structure(s).Lofstrom/Klein5.2.1.1.1 4514[Regarding word 'by']: Replace with ‘from’.Lofstrom/Klein5.2.1.2.2 4928 Table 5-19 The superscripts for C and D are incorrect.Commenter ChargeQuestionGuidanceSectionPageNumberLineNumberComment EPA ResolutionLofstrom/Klein5.2.1.3.2.3 523There should be an approach for evaluating a potential population overan area of subsurface contamination that is not based on the presence of acurrent structure.

# Peer Reviews

Tonia Burk (ATSDR)

• Charge Question Comments

• C V

• COI Certification

### Peer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a s ubsurface intrusion (SsI) component to the Hazard Ranking System (HRS). S ubsurface intrusion is the migration of hazardous substances from the unsaturated zone and/or the surf icial ground water into overlying structures. The HRS is the principal mechanism the EPA uses to evaluate site s for placement on the National Priorities List (NPL). The subsurface intrusion component addition (this add ition) would primarily expand the number of available options for EPA and state and tribal organizations pe rforming work on behalf of EPA to evaluate potential threats to public health and the environment from releases of hazardous substances.

This addition will allow the HRS evaluation to directly consider human exposure to hazardous substances that enter building structures through subsurface intrus ion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relative potential risk. The Agency is not considering changes to the remainder of the HRS except for minor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System should include expertise in:

Federal Agency Panelist : Panelist must have a strong working knowledge of policy and technical issues related to topic of vapor intrusion. Knowledge of r ecent developments in vapor intrusion technologies and research is required, in addition to working knowledge of federal vapor intrusion response programs. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous s ubstances is necessary. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

### Peer Review Charge Questions

1. Potential for subsurface exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a rele ase of a hazardous substance when an actual release has occurred through either chemical analysis or direct observation. The current HRS also evaluates the potential for a release to occur within the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is determined by the consideration of pathway specific factors that aid the site evaluator in predicting whether a release to the pathway is likely to occur. These factors are based on containment features of the source of contamination (whether or not hazardous substance can get out), route characteristics specific to each pathway (how far hazardous substances could migrate based on knowledge of site conditions) and include physical/chemical properties of the hazardous substances being evaluated (how the hazardous substances act in the environment).

Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure of
intruded hazardous substances for the subsurface intrusi on addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the Johnson-Ettinger m odel and also considered multiple lines of evidence approaches which estimate the levels of contaminant exposure based on numerous route characteristics. In addition, EPA examined the relationship between these factors to determine which have the greatest influence on the likelihood that an exposure would occur, and then incorporated these factors within its proposed approach. EPA also gave careful consideration to ensure that the data necessary to obtain route
characteristic factors could be measured or calculated on a site-specific basis and in a manner consistent with current HRS evaluations. Based on the Agency’s analysis, the following three factors for which sufficient site-specific information could be collected during a site inspection represented the greatest impact on the potential for exposure: (1) depth to contamination; (2) vertical migration; and (3) vapor migration potential (see Figure 1).

### Figure 1

Charge Question #1 : Is EPA’ s p roposed approa ch scientifically reasona ble for evaluating and assigning proportional weightings for the following whe n evaluating potential for exposure ? If no, what al ternative approach would you recommend?

a. Consideration of the construction/structure type for which sufficient site-specific information could be collected during a site inspection for the occupied structure;
b. Distance be tween occupied structure and depth of contamination; and c. Evaluation of the vertical migration factor based on the thickness and porosity /permeability of geologic materials in the interval between the lowest point of an occupied structure and the highest known point of hazardous substances in the subsurface.

Response 1.a. No mention of the potential for intrusion from wet basements or factors affecting indoor air pressure and exchange rate, such as HVAC systems or structural integrity (“leakiness”) of building, was identified. Section 5.2.1.1.2.1 Structure Containment of the HRS Rule document may be an appropriate place to add consideration of these topics. Response 1.b. Agreed, reasonable. Response 1.c. Consideration of the possibility for hydr aulic pumping in areas prone to rapid rise of the groundwater table may warrant a higher ranking. For example, vapor intrusion events in Hartford, IL have been correlated with rise in the Mississippi River and, to a lesser extent, rainfall

### (http://www.atsdr.cdc.gov/HAC/pha/HartfordResidentia lCommunity/HartfordRes identialCommunityLHC02 -24-2010.pdf).

### 2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity factor reflects the risk consideration related
to the m agnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pathways. At each site evaluated, EPA uses a four-tiered hierarchy for calculating the hazardous waste quantity that is based on (1) constituen t quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original sources (how much has migrated and how much can be released in the future). In the soil exposure pathway, the hazardous waste quantity does not include the total amount of hazardous substances in all site sources, but rather is based on the amount of hazardous substances to which a receptor can be exposed where actual contamination has been documented. In other words, for the soil exposure pathway, the risk posed by a release of hazardous substances is directly related to the amount of hazardous substances that receptors are exposed to, as opposed to how much of the hazardous substances from the original sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrusion a ddition to the HRS. Since the subsurface intrusion component also focuses on exposure, the waste quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar four- tiered hierarchical approach to calculate hazardous waste quantity within occupied structures with contaminat ion. In cases where no home is subject to actual contamination, EPA is proposing to use minimum waste qua ntity factors. In situations where there is an observed release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantity factor value. This value is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and air pathways and reflects the increased exposure risk of a release within an occupied structure.

Charge Question #2: Is EPA’s approach of basing the hazardous waste quantity on the amount of contaminants that could be found in the intruded structures appropriate? If no, what alternative approach would you recommend? Response 2. Agreed, appropriate.

### 3. Population score Background: Within the current HRS, receptors are evalua ted in two main categories: whether they are exposed to 1 ) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting obs erved release criteria, they are identified as actually contaminated; however, if the receptors are not expose d to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially contaminated. Actual contamination is further divided into two sub-categories based on whether the hazardous substance is present
at or above a health-based benchmark. If the concen tration of the hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multiplied by a factor of 10) in scoring. If the release concentrations are less than a health-based benchmark, the receptors are identified as Level II recepto rs and are not weighted (multiplied by a factor of 1). Potential receptors are distance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to the site score.

Proposed Approach: EPA is proposing to generally use the same receptor weighting structure in the subsurface intrusion component as the one used in th e current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in the area(s) of subsurface contamination (ASC) are considered potentially contam inated (See Figure 2). The receptors in an AOE are
further differentiated based on whether the contaminant concentrations are at levels above identified benchmarks (Level I) or are at levels establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use fo r the subsurface intrusion component are:

• Screening concentration for cancer effects; and

• Screening concentration for non-cancer effects (systemic toxicants).

Consistent with the weighting of populations throughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II contaminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of targets within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential receptors within the ASC receive less weight (population multiplied by a factor of 0.1), except in cases where a sub-slab sample indicates contaminant levels are at least 10 times higher than a health-based benchmark (population is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting reflects the observation that for approximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustment applied to the health-based benchmark reflects EPA’s finding that, in such paired sampling events, the indoor air sample concentration is, on average, 10 times lower than the sub-slab sample concentration.

### Figure 2

Charge Question #3: Is it appropriate to consider individuals/populations located within the area of subsurface contamination (ASC) to be at a higher relative risk in situations when sub-slab contaminant concentrations are at least ten times greater than a health-based benchmark? If no, please explain.

Response 3. Agreed, however, the last bullet in section 5.2.1.2.2 of the HRS Rule document includes enclosed crawl spaces in this criteria. Since EPA’s de fault attenuation factor for crawl space intrusion to indoor air is 1, the crawl space criteria may be better stated as considering populations when crawl space concentrations are greater than a benchmark (instead of 10 times a benchmark).

### 4. Multi-story and multi-tenant structures Background: In the current HRS, multi-story and m ulti-tenant buildings are evaluated based on population associated with an actually or potentially impacted target. In the ground water pathway, all residents who are served by a well are considered subject to the actual or potential contamination of the well. In the air pathway, all residents who have an opportunity to breathe ambient air are considered subject to the actual or potential contamination of the ambient environment w ithin a distance category. All receptors within a contaminated surface water stretch are subject to the level of contamination associated with that surface water stretch. In the soil exposure pathway, receptors must be able to come in contact with areas of contamination. In determining the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/use areas within a 200 foot areal extent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multi-story (the assumption being that is reasonable for people to use the outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story/multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenant/m ulti-story building. EPA is proposing to consider all receptors exposed to actual contamination as the population inhabiting the floor of the int ruded space and the population inhabiting the floor above and the floor below the intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, while also minimizing the potential for over counting (Figure 3).

Figure 3

### Charge Question #4: When calculating waste quantity and population, is it scientifically reasonable for populations in multi-story or multi-tenant structures to be evaluated based on using only the population inhabiting the intruded space and the population on the floor above and below the intruded space (For example, if contamination is found on the first floor, population from the basement and second floor would be used in the calculation. If contamination is found on the fifth floor, population from the fourth floor and
sixth floor would be used in the calculation – for fu rther explanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, what alternative approach would you recommend?

Response 4. The charge question seems to be worded differently than the description in the HRS Rule document on this topic. The charge question considers only the contaminated floor and one floor below and above the contaminated floor. Sections 5.2.1.3.2.1 and 5.2.1.3.2.2 say to consider those populations living

within the story with Level I/II concentrations and those stories below that story. Section 5.2.1.3.3 says to
count those workers in the highest story with observed exposure, one story above and all stories below . I agree with either approach with a caveat: preferential pathways, such as elevators and ventilation systems, may serve to transport hazardous vapors to distant floors. It may be prudent to consider the possibility of discontinuous contamination from floor to floor and not rule out floors that have not been sampled in such cases. Also, if a preferential pathway has not been iden tified to contamination in an isolated upper floor, all
floors below seem at risk.

5. Factor Value for Workers Background: In the current HRS, for the resident p opulation threat of the soil exposure pathway, a factor value for workers is assigned based on the total number of workers present within the area of observed contamination. These factor values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker factor va lue in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). However, since it is anticipated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamination, EPA is proposing to assign workers exposed to subsurface intrusion a higher weighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to su bsurface intrusion within the workplace than it is for workers exposed to outdoor surface contaminat ion at the workplace? If no, please explain.

Responst 5. Agreed reasonable.

### WORK EXPERIENCE

Position: Environmental Hea lth Scientist Dates Employed: 11/2006 - present Employer: U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, Division of Health Assessment and Consultation, Site a nd Radiological Branch Address: 4770 Buford Hwy, Mailstop F-59, Atlanta, GA 30341 Responsibilities: Review information on environmental contamination and make recommendations to protect public health using the recent scientific body of knowledge, writing skills and interpersonal communication skills. Serve as agency expert on vapor intrusion.

Position: Human Health Risk Assessment Analyst Dates Employed: 5/2002 - 11/2006 Employer: State of Georgia, Departme nt of Natural Resources, Environmental Protection Division, Hazardous Waste Management Branch, Corrective Action Program Address: Suite 1154, East Floyd To wer, 2 MLK Jr Dr, Atlanta, GA 30334 Responsibilities: Review and critique risk assessment repor ts, policies and regulations. Assist field teams with environm ental sampling. Provide technical assistance regarding environmental contaminants for internal and external inquiries. Speak to concerned citizens.

EDUCATION

Ph.D. Chemical Engineering, May 2001 Minor: Biochemistry/Genetics Dissertation: Surface Characteriza tion and Interactions in a Dry Powder Inhalant Drug Delivery System Auburn University, AL US

Dual Degree Undergraduate B.S., Chemical Engineering, Auburn University, AL, Aug 1994 B.A., Math, Huntingdon College, Montgomery, AL Jun 1995

CERTIFICATIONS OSHA, 29 CFR 1910.120 (HAZWOPER) Heartsaver First Aid, Am erican Heart Association Tonia R. Burk

4770 Buford Hwy NE Mailstop f-59 Atlanta, GA 30341 fxt9@cdc.gov

### SUBJECT MATTER EXPERT EXPERIENCE

Teaching

ATSDR Vapor Intrusion Workshop , course coordinator, Aug 2007, Agency for Toxic Substances and Disease Registry, Atlanta, GA

Public Health Assessment of Vapor Intrusion , ATSDR Basic Health Assessor Course, presenter, Jun 2008-9, Agency for Toxic Substa nces and Disease Registry, Atlanta, GA

Presentatio n
ATSDR Health Assessment of Vapor Intrusion at Mil itary Facilities (Abstract #10073)

, Environment Energy & Sustaina bility Symposium & Exhibi tion: Soil and Groundwater Contamination Session, Denver, CO, June 16 2010.

Current {Vapor Intrusion} Evaluations at ATSDR Associated with DoD , Multi-services DoD Panel, Crystal City, VA Aug 2009

ATSDR Health Assessment of TCE Exposure by Vapor intrusion at Military Facilities, Environment Energy & Sustaina bility Symposium & Exhibi tion in Denver CO, May 4
2009.

Public Health Assessment of Vapor Intrusion, Board of Scientific Counselors Meeting,
Nove mber 2008, Atlanta, GA.

Public Health Effec ts from Vapor Intrusion, Morehouse School of Medicine Grand Rounds, October 2008, Atlanta, GA.

Vapor Intrusion at Military Sites: An ATSDR Overview , Joint Services Environm ental Manageme nt Training Conference & Exposition: Environment and Energy Management in a Transforming DoD, May 5, 2008, Denver, CO.

Public Health Assessment of Vapor Intrusion , Region 6 ATSDR Partnership meeting in Dallas, TX, February 2008.

An Approach to Protecting the Public from Vapor Intrusion at a Well Defined Site: A Screening Procedure for Kelly AFB, San Antonio, TX, Regions 2 ATSDR/ EPA Meeting, Bear Mountain, NY, October 2007

An Overview of ATSDR's Perspective on Vapor Intrusion , Region 8 & 9 ATSDR/EPA Meeting, Las Vegas, NV, September 2007

An Overview of the ITRC Guidance on Vapor Intrusion Guidance , ATSDR Vapor Intrusion Workshop, August 2007

Risk Assessment of Air Toxics in Georgia , in the US EPA Re gional Risk Assessors Conference, San Francisco, CA, 2006.

# Peer Reviews

Blayne Hartman (Hartman Environmental Geoscience)

• Charge Question Comments

• CV

• COI Certification

## Comments on Proposed HRS Rule Addition of a Subsurface Intrusion Component to the Hazard Ranking System

Dr. Blayne Hartman
858-204-6170 blayne@hartmaneg.com

February 10, 2012

Key Comments on this Document

• There needs to be a distinction in this rule between petroleum hydrocarbon VOCs which readily bioattenuate and recalc itrant VOCs (typically those containing halogens) that do not bioattenuate. I do not see any allowance for this under vapor migration potential factors.

• One idea to distinguish between VOCs that bioattenuate versus those that don’t would be to come up with a bioattenua tion factor. These factors would be 0.1, 0.01, 0.001, and 0.0 using exclusion criteria that EPA-OUST is now considering.

• Setting benchmarks for cancer effects at 1e-6 risk level and for non-cancer at a HI=1is going to suck in almost every site as the screening levels for many compounds are below ambient levels. Si nce your goal is to rank the highest priority sites, you should se t the benchmarks for cancer at 1e-4 risk and noncancer at HI=10. This will accomplish the HRS goal of ranking the highest priority sites but not bog down your ranking with a large number of sites to rank that are unlikely to have a vapor intrusion concern.

• In some places (such as table 5-13 and s ection 5.2.1.3.2.3), the rule is inconsistent with current & forthcoming EPA vapor intrus ion guidances. This rule needs to be compliant with the two guidances co ming out in March by EPA-OSWER & EPAOUST.

Feel free to contact me with any questions on these comments.

Blayne HartmanPeer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a s ubsurface intrusion (SsI) component to the Hazard Ranking System (HRS). S ubsurface intrusion is the migration of hazardous substances from the unsaturated zone and/or the surf icial ground water into overlying structures. The HRS is the principal mechanism the EPA uses to evaluate sites for placement on the National Priorities List (NPL). The subsurface intrusion component addition (this add ition) would primarily expand the number of available options for EPA and state and tribal organizations pe rforming work on behalf of EPA to evaluate potential threats to public health and the environment from releases of hazardous substances.

This addition will allow the HRS evaluation to directly consider human exposure to hazardous substances that enter building structures through subsurface intrus ion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relative potential risk. The Agency is not considering changes to the remainder of the HRS except for minor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System should include expertise in:

Panelist from non-specified sector: Panelist must have a strong working knowledge of policy and technical issues related to the topic of vapor intrusion. Knowledge of recent developments in vapor intrusion technologies and research is required, in addition to working knowledge of federal vapor intrusion response programs. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous substances is necessary. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

Peer Review Charge Questions

1. Potential for subsurface exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a release of a hazardous substance when an actual release has occurred through either chemical analysis or direct observation. The current HRS also evaluates the potential for a release to occur within the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is determined by the consideration of pathway specific factors that aid the site evaluator in predicting whethe r a release to the pathway is likely to occur. These factors are based on containment features of the source of contamination (whether or not hazardous substance can get out), route characteristics specific to each pathway (how far hazardous substances could migrate based on knowledge of site conditions) and in clude physical/chemical properties of the hazardous substances being evaluated (how the hazardous substances act in the environment).Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure of
intruded hazardous substances for the subsurface intrus ion addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the Johnson-Ettinger m odel and also considered multiple lines of evidence approaches which estimate the levels of contaminant exposure based on numerous route characteristics. In addition, EPA examined the relationship between these factors to determine which have the greatest influence on the likelihood that an exposure would occur, and then incorporated these factors within its proposed approach. EPA also gave careful consideration to ensure that the data necessary to obtain route characteristic factors could be measured or calculated on a site-specific basis and in a manner consistent with current HRS evaluations. Based on the Agency’s analys is, the following three factors for which sufficient site-specific information could be collected during a site inspection represented the greatest impact on the potential for exposure: (1) depth to contamination; (2 ) vertical migration; and (3) vapor migration potential (see Figure 1).

Figure 1

Charge Question #1 : Is EPA’s prop osed approa ch scientif ic ally reasonable f or evaluating and assigning proportional weightings for the following whe n evaluating potential f or exposure? I f no, what al ternative approach would you recommend? Comment [B1]: No, it is not scientifically reasonable using these 3 factors alone.a. Consideration of the construction/structure t ype for which sufficient site-specific information could be collected during a site inspection for the occupied structure;
b. Distance be tween occupied structure and depth of contamination; and

c. Evaluation of the vertical migration f actor based on the thickness and porosity/permeability of geologic materials in the interval between the lowest point of an occupied structure and the highest known point of hazardous substances in the subsurface. Comment [B2]: This is a better approach than the one written above. However, this approach is also flawed if bioattenuation is not included into the vertical migration factor/potential. As now written, Section 5.2.1.1.2.3 & 4 & 5 have no allowance for bioattenuation, so the approach is fundamentally flawed for any VOCs that can bioattenuate such as vinyl chloride and petroleum VOCs.2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity factor reflects the risk consideration related to the magnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pathways. At each site evaluate d, EPA uses a four-tiered hierarchy for calculating the hazardous waste quantity that is based on (1) constituent quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original sources (how much has migrated and how much can be released in the future). In the soil exposure pathway, the hazardous waste quantity does not include the total amount of hazardous substances in all site sources,
but rather is based on the amount of hazardous substances to which a receptor can be exposed where actual contamination has been documented. In other words, for the soil exposure pathway, the risk posed by a release of hazardous substances is directly related to the amount of hazardous substances that receptors are exposed to, as opposed to how much of the hazardous substances from the original sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrusion a ddition to the HRS. Since the subsurface intrusion component also focuses on exposure, the waste quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar four-tie red hierarchical approach to calculate hazardous waste quantity within occupied structures with contamination. In cases where no home is subject to actual contamination, EPA is proposing to use minimum waste qua ntity factors. In situations where there is an
observed release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantity factor value. This value is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and ai r pathways and reflects the increased exposure risk of a release within an occupied structure.

Charge Question #2: Is EPA’s approach of basing the hazardous waste quantity on the amount of
contaminants that could be found in the intruded struct ures appropriate? If no, what alternative approach would you recommend? Comment [B3]: This approach is appropriate, but what is not appropriate is defining the level I & II benchmarks at a 1 in 1 million risk level. Much too low. You should set benchmarks at a 1 in 10,000 risk level.3. Population score Background: Wit hin the current HRS, receptors are evalua ted in two main categories: whether they are exposed to 1) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting obs erved release criteria, they are identified as actually contaminated; however, if the receptors are not expose d to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially contaminated. Actual contamination is further divided into two sub-categorie s based on whether the hazardous substance is present
at or above a health-based benchmark. If the concen tration of the hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multiplied by a factor of 10) in scoring. If th e release concentrations are less than a health-based benchmark, the receptors are identified as Level II receptors and are not weighted (multiplied by a factor of 1). Potential receptors are distance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to the site score.

Proposed Approach: EPA is proposing to generally use the same receptor weighting structure in the subsurface intrusion component as the one used in the current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in the area(s) of subsurface contamination (ASC) are considered potentially contaminated (See Figure 2). The receptors in an AOE are
further differentiated based on whether the contaminan t concentrations are at levels above identified benchmarks (Level I) or are at levels establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use for the subsurface intrusion component are:

• Screening concentration for cancer effects; and

• Screening concentration for non-cancer effects (systemic toxicants).

Consistent with the weighting of populations th roughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II contaminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of target s within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential receptors within the ASC receive less weight (population multiplied by a factor of 0.1), except in cases where a sub-slab samp le indicates contaminant levels are at least 10 times higher than a health-based benchmark (population is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting reflects the observation that for appr oximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustment applied to the health-b ased benchmark reflects EPA’s finding that, in such paired sampling events, the indoor air sample concentra tion is, on average, 10 times lower than the sub-slab sample concentration.Figure 2

Charge Question #3: Is it appropriate to consider individua ls/populations located within the area of subsurface contamination (ASC) to be at a higher rela tive risk in situations when sub-slab contaminant concentrations are at least ten times greater than a health-based benchmark? If no, please explain. Comment [B4]: EPA OSWER has released a paper evaluating attenuation factors, including sub-slab to indoor air attenuation factors. The factor of 10 you refer to in the above paragraph is not an average. It is a 95 th percentile. If you are going to use an average as you indicate, than the factor of 10 should be significantly higher. A paper released in 2011 says that a more reasonable subslab to indoor air attenuation factor is 50x. So, while it is appropriate to consider individuals/populations located within the area of subsurface contamination (ASC) to be at a higher relative risk in situations when sub-slab contaminant concentrations are high, the weighting factor of 0.75 should not apply until sub-slab values are at least 50 times higher than indoor air values rather than 10x higher.4. Multi-story and multi-tenant structures Background: In the curre nt HRS, multi-story and multi-tena nt buildings are evaluated based on population associated with an actually or potentially impacted target. In the ground water pathway, all residents who are served by a well are considered subject to the actual or potential contamination of the well. In the air pathway, all residents who have an opportunity to breathe ambient air are considered subject to the actual or potential contamination of the ambient environment within a distance category. All receptors within a contaminated surface water stretch are subject to the level of contamination associated with that surface water stretch. In the soil exposure pathway, receptors must be able to come in contact with areas of contamination. In determining the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/use areas within a 200 foot areal ex tent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multi-story (the assumption being that is reasonable for people to use the outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story /multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenant/multi-story building. EPA is proposing to consider all receptors exposed to actual contamination as the population inhabiting the floor of the intruded space and the population inhabiting the floor above and the floor below the intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, while also minimizing the potential for over counting (Figure 3).Figure 3 Charge Question #4: When calculating waste quantity and population, is it scientifically reasonable for populations in multi-story or multi-tenant structures to be evaluated based on using only the population inhabiting the intruded space and the population on the floor above and below the intruded space (For example, if contamination is found on the first floor, population from the basement and second floor would be used in the calculation. If contamination is found on the fifth floor, population from the fourth floor and
sixth floor would be used in the calculation – for further explanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, what alternative approach would you recommend? Comment [B5]: This protocol is okay so long as there are no elevators in the building or pipe/electrical chases that act as vapor conduits between lower & upper floors.5. Factor Value for Workers Background: In the curre nt HRS, for the resident population threat of the soil exposure pathway, a factor value for workers is assigned based on the total number of workers present within the area of observed contamination. These factor values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker factor valu e in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). However, since it is anticipated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamination, EPA is proposing to assign workers exposed to subsurface intrusion a higher we ighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to subs urface intrusion within the workplace than it is for workers exposed to outdoor surface contamination at the workplace? If no, please explain. Comment [B6]: There’s no explanation as to where the factor of 3 came from. Hence, while it is reasonable to assume the risk is greater, I feel the basis for the factor of 3 should be explained.

## Vapor Intrusion Support Services

Hartman Environmental specializes in vapor intrusion support services. Blayne Hartman has been performi ng vapor intrusion assessments since the mid 90s and has performed soil gas sampling since the mid 80s. Hartman’s vast connections throughout the vapor intrusion community enable him to call in additional expertise as needed for a specific project. Hartman typically works with the local consultant to provide the necessary expertise for assessing the vapor intrusion pathway. These services include:

• Assessment program design (type of samples, where to sample)

• Determination of site-specific screening levels

• Indoor air and soil gas field sampling and/or sampling supervision

• On-site analysis of indoor air and/or soil gas samples by 8021, 8260, TO-15, TO-17

• Data review and interpretation.

• Risk calculations using J-E models.

• Preparation of workplans and interpretive reports.

• Review of workplans prepared by others.

• Review of interpretive reports prepared by others.

• Interaction with regulatory agencies.

• Training on the vapor intrusion pathway and sampling methods.

• Mitigation system design & installation

• Expert witness and litigation support

## Biosketch - Dr. Blayne Hartman

Blayne Hartman received his Ph.D. in geochemistry from the University of Southern California. He co- founded & operated H&P Mobile GeoChemistry, a business partnership offering on-site laboratory analysis, direct push environm ental sampling, soil vapor surveys, and vapor intrusion services for twenty years. He sold H&P in 2008 and is currently an independent consultant offering vapor intrusion and soil gas support.

Dr. Hartman is a nationally recognized expert on soil vapor sampling, soil vapor analysis, and vapor intrusion. He has provided training on soil gas methods and vapor intrusion to County and State regulatory agencies in over 30 states, many of the EPA regions, the DOD, and numerous stakeholder groups and consultants. He has written numerous articles on the collection, analysis, and interpretation of soil vapor data, including chapters in four textbooks. He has participated in technical workgroups on soil vapor methods for EPA, CA-EPA, CA Regional Water Boards, County of San Diego, ITRC & ASTM and has reviewed/edited instructional manuals for the EPA OUST and Superfund groups. Over the past four years, Dr. Hartman has been a contributing author/editor to vapor intrusion and soil gas guidance documents to federal EPA, CA-EPA, San Diego County, ITRC, DOD, API, and more than 25 individual State documents. He is currently a trainer in the EPA-OUST, ITRC, and API vapor intrusion courses and was form erly a co-trainer of the ASTM vapor intrusion course.

## Complete Resume – Blayne Hartman, Ph.D.

EDUCATION

Ph.D., Geological Sciences - 1983; University of Southern California, Los Angeles, CA

M.S., Geological Sciences - 1978; University of Southern California, Los Angeles, CA

B.S., Chemical Engineering- 1975; Clar kson University, Potsdam, New York

EMPLOYMENT HISTORY

Present: Hartman Environm ental Geoscience, Vapor Intrusion Assessm ents of methane and volatile organic compounds (VOCs), Soil Gas Support

1998 to 2008: H&P Mobile Geochemistry, Carlsbad, CA, 92010 Founder, partner, principal geochemist.
1988 to 1998: Transglobal Exploration and Geoscience (TEG), Inc. , Solana Beach, CA President , founder, principal geochemist.
1986 to 1988: InterOcean Systems, Inc. , San Diego, California, Chief Geochemist
1982 to 1986: Unocal Science and Technology Division , Brea, California Research Geochemist

SUMMARY OF PROFESSIONAL EXPERIENCE

Dr. Hartman is a nationally recognized expert on soil vapor sampling, soil vapor analysis, and vapor intrusion of volatile compounds and methane. He has provided training on soil gas m ethods and vapor intrusion to County and State regulatory agencies in over 30 states, m any of the EPA regions, the DOD, and num erous stakeholder groups and consultants. He has written num erous articles on the collection, analysis, and interpretation of soil vapor data, includi ng chapters in four textbooks. He has participated in technical workgroups on soil vapor m ethods for EPA, CA-EPA, ITRC, ASTM, CA Regional W ater Boards, Count y of San Diego, has reviewed/edited instructional manuals for the EPA OUST a nd Superfund groups, and lectured on soil gas methods in the EPA-OSW ER vapor intrusion se minars. He has been involved with five research studies with EPA-ORD on soil gas methods, soil gas tem poral variations and indoor air variations in 2011, 2010, 2009, 2008, & 2007.

### At H&P Geochem istry, Dr. Hartm an was prim arily responsible for geochem ical data interpretation, corporate and business developm en t, and method development. As Founder and President of TEG, Dr. Hartm an was personally responsible for geochem ical technical development, equipment design and m aintenance, laboratory director, applications developm ent, and implementation of exploration programs, an alyses, and reporting. Prior to co-founding TEG, Dr. Hartman was chief m arine geochemist with InterOcean Systems, where his responsibilities included direction of marine sediment and bottom- water geochemical explor ation programs. As a research chem ist with Unocal Research, Dr. Hartm an was responsible for development of geochemical prospecting 

### techniques in onshore and offs hore applications including fingerprinting of methane and light hydrocarbons using isotopes.

PRESENTATIONS & TRAINING ON SOIL GAS METHODS & VAPOR
INTRUSION

Too numerous to list. Go to www.handpmg.com , Presentations & Training for a partial list.

RECENT PUBLICATIONS ON SOIL GAS METHODS & VAPOR INTRUSION

Hartman, B. (2010). Vapor Intrusion Pathway: Regulatory Updates and Issues Specifically for Petroleum Hydrocarbons, LustLine, November 2010.

McHugh, Thomas E., Ham mond, Douglas E., Ni ckels, Tim & Hartman, Blayne (2008) 'Use of Radon Measurements for Evaluation of Volatile Organic Compound (VOC) Vapor Intrusion ', Environmental Forensics, 9:1, 107 - 114

Hartman, B. et. al., (2007). Results from EPA Funded Research Programs on the Importance of Purge Volume, Sample Volume, Sample Flow Rate and Temporal Variations On Soil Gas Concentrations. Proceedings AWMA Vapor Intrusion Conference, Providence, RI, September 2007

Hartma n, B. (2006). How to Collect Reliable Soil Gas Data for Risk Based Applications, Part 4: Updates on Soil Gas Collection & Analytical Procedures, LustLine #53, September 2006.

Hartman, B. (2004). How to Collect Reliable Soil Gas Data for Risk Based Applications, Part 3: Answers to Frequently Asked Questions, LustLine, Novem ber
2004.

Hartman, B. (2003). How to Collect Reliable Soil Gas Data for Risk Based Applications, Part 2: Surface Flux Chamber Method, LustLine #44, NEIW PIC, August 2003.

### Hartman, B. (2002). How to Collect Reliable Soil Gas Data for Risk Based Applications, Part 1: Active Soil Gas Method , LustLine #42, NEIWPIC, October
2002.

Hartman, B. (2002). Reevaluating the Upward Vapor Migration Rick Pathway,
LustLine #41 , NEIWPIC, June 2002.

Hartman, B. and J. Jacobs (2000a). Soil vapor principles , in Standard Handbook of Environmental Science, Health, and Technology, Lehr, J. and J. Lehr, eds., Mc Graw Hill, ISBN#0-07-038309-X.

Hartman, B. and J. Jacobs (2000b). Applications and interpretation of soil vapor data to volatile organic compound contamination , in Standard Handbook of Environmental Science, Health, and Technology, Lehr, J. and J. Lehr, eds., Mc Graw Hill, ISBN#0-
07-038309-X.

Hartman, B. (1999). Applications and Interpretation of Soil Vapor Data , in Chlorinated Solvent Contamination: Legal and Technical Issues, Morrison et.al., eds., Argent Communications Group, Foresthill, CA.

Hartman, B. (1998a). Applications and Interpretation of Soil Vapor Data, in Petroleum Hydrocarbon Contamination : Legal and Technical Issues, Morrison et.al., eds., Argent Communications Group, Foresthill, CA.

Frez, W.A., Tolbert, J.N., Hartman, Blayne, and T.R. Kline (1998), Determining Risk Based Remediation Requirements Us ing Rapid Flux Chamber Technology , in proceedings, Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, Battelle Press

Hartman, B. (1998). The Downward Migration of Vapors , LUSTLine Bulletin 28, NEIWPCC, Wilmington, MA, December 1998.

Hartman, B. (1997). The Upward Migration of Vapors , LUSTLine Bulletin 27, NEIWPCC, Wilmington, MA, December 1997.

## RECENT PROJECTS/PUBLICATIONS WITH EPA

USEPA (2010) Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab Soil Vapor Probe Equilibra tion Study, EPA Contract No. EP-C-05-061 Task Order No. 65, Modification 7 http://www.epa.gov/nerlesd1/cmb/research.htm #schumacher

USEPA (2009). Vertical distribution of VOCs in soils from groundwater to the surface/subslab. EPA/600/R-09/073, August 2009. http://www.epa.gov/nerlesd1/cmb/research.htm#schumacher

USEPA (2007a). Final project report for the development of an active soil gas sampling method. EPA/600/R-07/076, July 2007. http://www.epa.gov/nerlesd1/cmb/research.htm#schumacher

USEPA (2007b). Final project report for inves tigation of the influence of temporal variation on active soil gas/vapor sampling. EPA/600/R-07/141, December 2007. http://www.epa.gov/nerlesd1/cmb/research.htm#schumacher

DiGiulio, D., C. Paul, R. Cody, R. Willey, S. Clifford, P. Kahn, R. Mosley, A. Lee, K. Christensen (2006b). Assessment of vapor intrusion in homes near the Raymark superfund site using basement and sub- slab air samples. EPA/600/R-05/147, March 2006 (paid reviewer)

DiGiulio, D., C. Paul, R. Cody, R. Willey, S.Clifford, R. Mosley, A. Lee, K. Christensen (2006a). Comparison of Geoprobe PRT and AMS GVP soil-gas sampling systems with dedicated vapor probes in sandy soils at the Raymark superfund site. USEPA/600/R-06/111, October 2006. (paid reviewer)

Hartman, B. et. al., (2007). Results from EPA Funded Research Programs on the Importance of Purge Volume, Sample Volume, Sample Flow Rate and Temporal Variations On Soil Gas Concentrations. Proceedings AWMA Vapor Intrusion Conference, Providence, RI, September 2007 (primary author)

### REGULATORY GUIDANCE DOCUMENTS CONTRIBUTED TO

• CA Leaking Underground Fuel Tanks (LUFT) Manual, 2011

• EPA-OUST Vapor Intrusion Guidance, 2011

• San Diego County Dept. Env. Health Soil Gas Collection Guidance, 2011

• San Diego County Dept. Env. Health Soil Gas Analytical Guidance, August 2011

• CA-EPA (DTSC) Soil Gas Collection Guidance, March 2010

• CA-EPA (DTSC) Soil Gas Collection Guidance, 2011 & 2003

• ASTM Vapor Intrusion Standard, March 2008

• ITRC Vapor Intrusion Guidance, February 2007

• States of CA, MO, MI, TN, AZ, NY, NJ, KS, IN, WA, NH, WI, AK, OH, HI

• San Diego County Building Dept. Methane Testing Ordinance, 2001

• EPA OUST Site Assessm ent Manual, 1997

• LA-RWQCB Soil Gas Analytical Guidance, 1997-1992

REFERENCES

• Jeff Kuhn, MT-DEP, jkuhn@mt.gov , 406-841-5055

• John Boyer, NJ-DEP, john.boyer@dep.state.nj.us , (609) 984-9751

• Kevin Graves, CA-SWQ CB, kgraves@waterboards.ca.gov , 916-341-5782

• Robin Davis, UT-DEP, rvdavis@utah.gov , 801-512-4767

• Brian Schumacher, EPA-ORD, schumacher.brian@epa.gov , 702-513-2661

• Lorraine LaFreniere, Argonne Nat’l Lab, lafreniere@anl.gov , 630-252-7969

• Todd Ririe, BP-Arco, TODD.RIRIE@BP.COM , 714-670-3062

• Robin Mongeon, NH-DEH, rmongeon@des.state.nh.us

• Richard Spiese, VT-DEP, R ichard.Spiese@state.vt.us

• John Menatti, UT-DEP, jmenatti@utah.gov , 801-536-4159

## CURRENT & RECENT PROJECT DESCRIPTIONS

Site: Clocktowers Site, Lancaster PA
Date Conducted: March 2011 to Present (project in progress)
Client: General Dynamics OTS Oversite Agency: PA-DEP & EPA Region 3 Project Description: Vapor intrusion assessment of TCE to existing school and residential units located on a f ormer watch manufacturing facility property. Hartman providing work scope, conducted soil gas, sub-slab soil gas, and indoor air sam pling programs, on-site analysis by Method TO-14, and data interpretation.

Site: Research House, Indianapolis, IN
Date Conducted: August 2011 to Persent (project in progress)
Client: Dr. Brian Schumacher, EPA-ORD, Las Vegas Oversite Agency: EPA-ORD Project Description: Research program by EPA studing temporal variation of soil gas and indoor concentrations. Hartman proving real-time, continuous (24 hour) monitoring of chloroform, TCE, and PCE by method TO-14 for a period of 4 months.

Site: Residential neighborhood, Phoenix AZ
Date Conducted: June 2011 to Present (project in progress)
Client: Motorola/Freescale Semiconductor Oversite Agency: EPA Region 9 Project Description: Vapor intrusion assessment of over 100 residential units located over a TCE groundwater plume. Hartman providing work scope, conducted soil gas, sub-slab soil gas, and indoor air sampling programs, and data interpretation.

Site: Residential neighborhood
, Miles City, MT
Date Conducted: May 2011 to present (project in progress)
Client: Trinity Industries, Dallas TX Oversite Agency: Montana DEQ Project Description: Vapor intrusion assessment of houses neighboring a rail yard located over diesel contamination. Hartman providing work scope, conducted soil gas, sub-slab soil gas, and indoor air sampling programs, and data interpretation.

### Site: 20 townships in rural Kansas
Date Conducted: 2008 through 2011
Client: USDA & Argonne National Laboratory Oversite Agency: Kansas DHE Project Description: Hartman consucted a preliminary vapor intrusion screening assessment of approxim ately 20 townships in rural Kansas with former or current grain storage silos using carbon tetrachloride. In Hanover KS, Hartm an provided a detailed vapor intrusion assessment of carbon tetrachloride in ~ 20 residences located near a former US grain storage site. Hartman provided work scope, conducted soil gas, sub-slab soil gas, and indoor air sampling programs, and data interpretation.

Site: Residential neighborhood
, Seal Beach, CA
Date Conducted: 2009 - 2010
Client: Arco Oversite Agency: CA-EPA Project Description: Vapor intrusion assessment of ~ 50 houses neighboring a operating Arco service station. Hartman providing work scope, conducted soil gas, sub-slab soil gas, and indoor air sampling programs, and data interpretation.

### Peer **Reviewer Conflict**  **of Interest**  **Certification**

**Peer Review:**  

### Proposed **Rule: Addition**  **of a**  **Subsurface Intrusion**  **Component to**  **the Hazard**  **Ranking System;**  **40 CFR**  **Part 300;**  **EPA-HQ-SFUND-2010-1086; FRL_XXXX-X**  **(review draft).** 

**A conflict**  **of interest**  **or lack**  **of impartiality**  **exists when**  **the proposed**  **peer reviewer**  **personally (**  **or the**  **peer reviewer's**  **immediate family),**  **or his**  **or her**  **employer, has**  **financial interests**  **that may**  **be affected**  **by the**  **results of**  **the**

**peer review;**  **or may**  **provide an**  **unfair competitive**  **advantage to**  **the peer**  **reviewer (or**  **employer); or**  **if the peer**  **reviewer's objectivity**  **in performing**  **the peer**  **review may**  **be impaired**  **due to**  **other factors.**  **When the**  **Peer Reviewer**  **knows that**  **a reasonable**  **person with**  **knowledge of**  **the facts**  **may question**  **the peer**  **reviewer's impartiality**  **or financial**  **involvement, an**  **apparent lack**  **of impartiality**  **or conflict**  **of interest**  **exists.**

**The following**  **questions, if**  **answered affirmatively,**  **represent potential**  **or apparent**  **lack of**  **impartiality** 

### (any **affirmative answers should**  **be explained**  **on the**  **back of**  **this form**  **or in**  **an attachment):** 

**• Did**  **you contribute**  **to the**  **development of**  **the document**  **under peer**  **review, or**  **were you**  **consulted during**  **its development,**  **or did**  **you offer**  **comments or**  **suggestions to**  **any drafts**  **or versions**  **of the**  **document during**  **its development?** 

**J i** 

**( °K**  **lo D**  **Yes**

**• Do**  **you know**  **of any**  **reason that**  **you might**  **be unable**  **to provide**  **impartial advice**  **on the**  **matter under**  **consideration in**  **this peer**  **review, or**  **any reason**  **that your**  **impartiality in**  **the matter**  **might be**  **questioned? )tN**  **o D**  **Yes**

**• Have**  **you had**  **any previous**  **involvement with**  **the review**  **document(s) under**  **consideration? J(N**  **o D**  **Yes**

**• Have**  **you served**  **on previous**  **advisory panels,**  **committees, or**  **subcommittees that**  **have addressed**  **the topic** 

**under consideration** 

**� o**  **D Yes** 

**• Have**  **you made**  **any public**  **statements (written**  **or oral)**  **on the**  **issue? )(N**  **oo Yes** 

**• Have**  **you made**  **any public**  **statements that**  **would indicate**  **to an**  **observer that**  **you have**  **taken a**  **position on**  **the issue**  **under consideration?**  **}(N o**  **D Yes** 

**• Do**  **you, your**  **family, or**  **your employer**  **have any**  **financial interest(s)**  **in the**  **matter or topic**  **under peer**  **review,**

**or could**  **someone with**  **access to**  **relevant facts**  **reasonably cone**  **) �**  **that you**  **(or your**  **family or**  **employer)**
**stand to**  **benefit from**  **a particular**  **outcome of**  **this peer**  **review?**

**' �**  **No D**  **Yes**

**With regard**  **to real**  **or apparent**  **conflicts of**  **interest or**  **questions of**  **impartiality, the**  **following provisions**  **shall apply**  **for the**  **duration of**  **this peer**  **review:**

**(a) Peer**  **Reviewer warrants,**  **to the**  **best of**  **his/her knowledge**  **and belief,**  **that there**  **are no**  **relevant facts or**  **circumstances that**  **could give**  **rise to**  **an actual,**  **apparent, or**  **potential organizational**  **or personal**  **conflict of**  **interest,**

**or that**  **Peer Reviewer**  **has disclosed**  **all such**  **relevant information**  **to EMS**  **or to**  **EPA. (b)**  **Peer Reviewer**  **agrees that**  **if an**  **actual, apparent,**  **or potential**  **personal or**  **organizational conflict**  **of interest**  **is identified**  **during performance**  **of this peer**  **review, he/she**  **immediately will**  **make a**  **full disclosure**  **in writing**  **to EMS.**  **This disclosure**  **shall include**  **a description**  **of actions**  **that Peer**  **Reviewer (**  **or his/her**  **employer) has**  **taken or**  **proposes**
**to take**  **after consultation**  **with EMS**  **to avoid,**  **mitigate, or**  **neutralize the**  **actual, apparent,**  **or potential**  **organizational conflict**  **of interest.**  **Peer Reviewer**  **shall continue**  **performance until**  **notified by**  **EMS of**  **any contrary**  **action to**  **be taken.** 

**D Check**  **here if**  **any explanation**  **is attached**  

## s **; �** 

**Date** 

# Ziu **'f Al�**  **/ ../rt/t.f'MM** 

**Printed Name**  

# /bAfittM **fs**

**v ,**  **A u/J�Pt�**  **f%tb?!**

**�**
**Affiliation/Organization**

68 68

# Peer Reviews

Paul Johnson (Arizona State University)

• Charge Question Comments

• C V

• COI Certification

### Peer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a subsurface intrusion (SsI) component to the Hazard Ranking System (HRS). Subs urface intrusion is the migration of hazardous substances from the unsaturated zo ne and/or the surficial ground wa ter into overlying structures. The HRS is the principal mechanism the EPA uses to eval uate sites for placement on the National Priorities List (NPL). The subsurface intrusion component a ddition (this addition) would primarily expand the number of available options for EPA and state and tribal organizations perf orming work on behalf of EPA to evaluate potential threat s to public health and the envir onment from releases of hazardous substances.

This addition will allow the HRS evaluation to di rectly consider human exposure to hazardous substances that enter building structures through subsurface intrusion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relati ve potential risk. The Agency is not considering changes to the remainder of the HRS except for mi nor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subs urface Intrusion Component to the Hazard Ranking System should include expertise in:

Academia: Panelist must have experience working, resear ching, and developing opinions on the topic of vapor intrusion. Expertise in the history and recent developments of vapor intrusion research and development, remediation, and mitigation techno logies is required. Expertise in hydrogeology, chemistry, knowledge of public health risks associat ed with indoor air threat s, and the subsurface migration of volatile hazardous substances is necessary. Experience working on Superfund issues is highly recommended, but not necessary.

Peer Review Charge Questions

1. Potential for subsurfa ce exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a release of a hazardous substance when an
actual release has occu rred through either chemical analysis or direct observation. The current HRS also
evaluates th e potential for a release to occur with in the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is de termined by the consideration of pathway specific factors that aid the site evaluator in predicting whether a release to the pathway is likely to occur. These factors are based on containmen t features of the source of contamination (whether or not hazardous substance can get out), route ch aracteristics specific to each pathway (how far hazardous substances could migrate based on kn owledge of site conditions) and include

### physical/chemical properties of the hazardous subs tances being evaluated (how the hazardous substances act in the environment).

Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure
of intruded hazardous substances for the subsurface in trusion addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the J ohnson-Ettinger model and also considered multiple lines of evidence approaches whic h estimate the levels of contam inant exposure based on numerous route characteristics. In addition, EPA examined th e relationship between thes e factors to determine which have the greatest influence on the likelihood that an exposure w ould occur, and then incorporated these factors within its proposed approach. EPA also ga ve careful consideration to ensure that the data necessary to obtain route characterist ic factors could be measured or calculated on a site-specific basis
and in a manner consistent with current HRS evalua tions. Based on the Agency’s analysis, the following three factors for which sufficient site-specific info rmation could be collecte d during a site inspection represented the greatest impact on the potential for e xposure: (1) depth to cont amination; (2) vertical migration; and (3) vapor migr ation potential (see Figure 1).

Figure 1

### Charge Question #1 : Is EPA’s proposed approach scientifically r easonable for evaluating and assigning proportional weightings for the follo wing when evaluating potential for exposure? If no, what alternative approach would you recommend?

Overall, the structure of this section seems to be based more on conventional wisdom (and c ommon pathway misconceptions) than on th e latest understanding gained from theory/modeling and criticallyreviewed empirical observations.

For example, field data and modeling show that the si ngle-most significant infl uence on vapor intrusion impacts is whether or not a chemical is aerobica lly biodegradable, and that is not considered here.

In addition, for chemicals that do no t significantly biodegrade during va por transport (i.e., chlorinated solvents), the potential significance of vapor intrusion impacts is pr imarily related to the quantity {(C

D eff 

### /L A B 

### )/(Q B 

### C target 

### )}, where C is the source concentra tion, D eff 

### is the overall effective vapor d iffusion coefficient, L is the dep th to the concentration C, A B 

### and E B 

### are the building footprint and exchange rate, and C target 

### is the target concentration for adverse impacts. Of these quantities, the ones that might vary most from site to site and have the greatest influence on the pot ential for adverse impacts are the ratios (C/C target 

### ) and (D eff 

### /L). The first is a meas ure of how strong the source is, while the second is a measure of the overall resistance to transport through the soil. The relative interplay between these quantities, the strength of the source , and the realistic sensitivity of (D eff 

### /L) to depth and soil type are not reflected in the proposed approach.

The proposed approach could be replaced by a simp ler one based on only two primary factors: one derived from (C/C target 

### ) ratios and one from a soil type vs. depth t able. There could also be a modifying factor for chemical degradabilit y that would be based on (total of all biodegradable concentrations/oxygen c ontent in air and depth).

a. Consideration of the constructio n/structure type for which suffi cient site-specific information could be collected during a site insp ection for the occupied structure;

With respect to Table 5-12 (structure containment), I am not aware of definitiv e studies or significant anecdotal experiences that support the inclusion of Items 4, 5, or 7. USEPA’s empirical database does not show a clear dependence on foundation constructi on (Item 4) and I am not aware of any definitive validation studies of the performance of passive systems (Items 5 and 7). It is also not clear that Item 3 is needed either, especially given its value and the real ity that it is not feasible to identify all intrusion points to buildings. Item 1 should in clude evidence of intrusion of haz ardous contaminants (not just nonhazardous contaminants). This table could probably be reduced to three items (current Item 1 combined with Item 2, a combined It em 6 and Item 8, Item 9)

b. Distance between occupied structure and depth of contamination; and

### There are ambiguities and potential issues with application of Table 5-13 (depth to contamination) and its associated discussion. In particular, it is not clear if the authors intended for contaminant concentrations to be below background or detection levels for all distances less than this depth, or if it is simply the depth to the closest detection above ba ckground or detection levels? These are two very different concepts and have diff erent implications for use in a scoring system like this.

For example, if the authors intended contaminant concentrations to be below background or detection levels for all distances between the foundation a nd this depth, then Table 5-13 is likely overly

conservative.

On the other hand, if the depth to be used is the depth to the closest detection above background or detection levels (independent as to whether or no t there are non-detect/background-level samples until that point is encountered), then the table might not be suffic iently protective. For many sites, there may only be groundwater data available, and so people will be using depth to groundwater with Table 5-13. The vapor intrusion impact depende nce on depth to groundwater has not been shown through field data or modeling to be as significant as suggested by this table (e.g., m odeling would show that at most intrusion rates would be 10X less for a 200 ft dept h than for a 20 ft depth for comparable groundwater concentrations and soils, and empirical data show lit tle dependence on depth for the range of depths represented in the em pirical data set).

The following revisions are suggested:

1 ) Clarify the meaning of “dep th to contamination”.

2 ) If contaminant concentrations are supposed to be below backgr ound or detection levels for all distances less than this depth (unlikely to be ve rified with typical data used for ranking), then only two or three depth categories are justified a nd the value should be 0 for all depths greater than about 10 or 20 ft. 3) I f it is the depth to the clos est detection above background or de tection levels, then Depth to Contamination Assigned Values s hould not decline as significantly with depth as happens in Table 5-13. It is justifi ed to have a high value for cases with liquid in trusion or very shallow depths to groundwater, but depths to about 100 ft (most sites) should probably all have about the same value and depths greater than 100 ft (few sites) should probably have values that are within 50% of the <100 ft values. This is in part because there is a second important dimension not considered here in the factors – contaminant concentratio n. For example, a groundwater plume

w ith a 20 ug/L concentration at 10 ft depth poses the same risk as a groundwater plume with a 200 ug/L concentration at a 100 ft de pth and a groundwater plume with a 400 ug/L concentration at a 200 ft depth (all othe r factors being equal, and a non-biodegradable chemical).

c. Evaluation of the vertical migration factor based on the thickness and po rosity/permeability of

g eologic materials in the inte rval between the lo west point of an occupied structure and the
h ighest known point of hazardous substances in the subsurface.

### The vertical migration factor shoul d be presented as being related to “soil type” and not effective porosity/permeability as these quan tities are irrelevant to the v apor intrusion pathway and only soil descriptions are used in Table 5-14 anyway.

Categories 2 and 3 in Table 5-14 should be adjusted so th at “silty loams; loesses; silty clays; sediments that are predominantly silts; moderately permeable t ill (fine-grained, unconsolidated till, or compact till with some fractures)” should be included in Table 2. EPA’s own modeling in its pathway assessment guidance document (as well as other publications) and empirical data show little difference in behavior across this range of soil types.

Depth creeps in as an overly-sensitive modifying factor in Table 5-15, com pounding its use already in Table 5-13.

2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity fac tor reflects the risk consideration related to the magnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pa thways. At each site evaluated, EPA uses a fourtiered hierarchy for calculating the hazardous waste quan tity that is based on (1) constituent quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original s ources (how much has migrat ed and how much can be released in the future). In the soil exposure path way, the hazardous waste quantity does not include the
total amount of hazardous substances in all site sources, but rather is based on the amount of hazardous substances to which a receptor can be exposed wher e actual contamination has been documented. In other words, for the soil exposure pathway, the ri sk posed by a release of hazardous substances is directly related to the am ount of hazardous substances that rece ptors are exposed to, as opposed to how much of the hazardous substances from the origin al sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrus ion addition to the HRS. Since the subsurface intrusion component also focuses on exposure, the wast e quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar fou r-tiered hierarchical approach to calculate hazardous waste quantity w ithin occupied structures with contamination. In cases where no home is subject to actual contam ination, EPA is proposing to use minimum waste quantity factors. In
situations where there is an obser ved release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantit y factor value. This va lue is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and air pathways and reflects the increased exposure risk of a release within an occupied structure.

### Charge Question #2: Is EPA’s approach of basing the h azardous waste quantity on the amount of
contaminants that could be found in the intruded structures appropriate? If no, what alternative approach would you recommend?

It is suggested that this be elimin ated as a factor in assessing the relative risk of v apor intrusion, as hazardous waste quantity has little relevance to vapor intrusion im pacts, except to the extent that it might impact the longevity of th e contaminant vapor source.

The proposed approach makes little sense and is not tech nically defensible. The mass of contaminant in the residence is irrelevant for this pathway; instead it is the duration of time that the vapor source will produce vapor concentrations of significance that is th e relevant quantity. That in turn is related to source zone longevity (under natural or remediat ion conditions) and groundwat er migration rates for dissolved plume sources. That is likely to be a very long time – probably decades for most sites evaluated by this process, unle ss source removal and or control are going to reduce th e time frame to
less than a decade.

Source concentrations should be included some where in the analysis as discussed above.

3. Population score Background: Within the current HR S, receptors are evaluated in two main categories: whether they are exposed to 1) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting observed release criteria, they are identified as actually contaminated; however, if the receptors are not exposed to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially
contaminated. Actual contamination is further di vided into two sub-categories based on whether the hazardous substance is present at or above a hea lth-based benchmark. If th e concentration of the
hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multip lied by a factor of 10) in scoring. If the release concentrations are less than a health-based benchmark, the receptors are identified as Level II receptors and are not weighted (multiplied by a factor of 1). Po tential receptors are dist ance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to
the site score.

Proposed Approach: EPA is proposing to generally use the sa me receptor weighting structure in the subsurface intrusion component as the one used in th e current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in th e area(s) of subsurface contamination (ASC) are considered potentially cont aminated (See Figure 2). Th e receptors in an AOE
are further differentiated based on whether the contamin ant concentrations are at levels above identified benchmarks (Level I) or are at leve ls establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use for the subsurface intrusion component are:

• Screening concentration for cancer effects; and

### • Screening concentration for non-can cer effects (systemic toxicants).

Consistent with the weighting of populations throughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II cont aminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of targets within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential rece ptors within the ASC receive le ss weight (population multiplied by a factor of 0.1), except in cases where a sub-slab sa mple indicates contaminant levels are at least 10 times higher than a health-based benchmark (populat ion is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting re flects the observation that for approximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustme nt applied to the health-based benchmark reflects EPA’s finding that, in such paired sampling events, th e indoor air sample con centration is, on average,
10 times lower than the sub- slab sample concentration.

Figure 2

Charge Question #3: Is it appropriate to consid er individuals/populations lo cated within the area of subsurface contamination (ASC) to be at a h igher relati ve risk in situations when sub-slab contaminant
concentrations are at least ten tim es greater than a health-based be nchmark? If no, please explain.

### It should be recognized that th is approach is predicated on tw o assumptions, both of which have
weaknesses:

1) It is assumed that areas of subsurface cont amination have a 10X lowe r relative potential for impact than areas of observed contamination, and

2) Sub-slab soil gas samples are reliabl e indicators of v apor intrusion.

With respect to (1), the preamble document contains the paragraph:

“When an observed exposure has not been establishe d, the EPA is proposing to evaluate the potential for exposure within structures located in the ASC w ithin the subsurface intrus ion component. Given that contamination within an ASC is documented as presen t below these structures, th ere is a potential that intrusion and exposure to the intr usion has occurred but that sampli ng has not been performed at the time the exposure was taki ng place. As explained in section XXXX of the Proposal TSD, the factors affecting when intrusion will occur and the rate of subsurface intrusion are extremely time-, site- and climatic-specific. Sampling may not have been perf ormed in these structures, or, even if performed during the limited time period of a site inspection, the sampling may have been during conditions that the intrusion was not occurring or occurring at level s not detectable or differentiable from background sources of the contaminant. Site inspections are c onducted over a limited period (usually 1 to 3 days). Therefore it is important that the potential for expos ure be included as a consideration when evaluating subsurface intrusion threats.”

This paragraph reasonably captures the current state of the practice – na mely that conventional point in time and point in space sampling (e.g., Summa canist ers) has been shown to be inadequate for confidently assessing the presence or absence of vapor intrusion. In addition, empirical data have shown unacceptable and highly variable indoor air impacts at chlorinated solvent sites with groundwater concentrations as low as 10 ug/ L, with no clear dependence on groundwater concentration, soil type, or depth. T hus, the reality is that we are unable to confidently identify a priori whether homes are expected to be impacted, and which homes are likely to be the most impacted above a dissolved groundwater plume.

This proposed approach seems to ignore this. There is no basis for assigning lo wer risks to areas of subsurface contamination having similar subsurface c onditions as nearby area s of observed impacts simply because impacts have not been observed. It is arguably more appropriate to assume that the potential for exposure is the same in all areas havi ng similar conditions, unless there has been extensive data collection to prove otherwise. The other fact ors discussed above already reflect differences in potential for impacts bas ed on soil type and depth.

USEPA’s database (raw data – not the alpha factor analys is) should be reviewed carefully in dealing with the issue of relative risk of observed areas of exposure vs. areas of subsurface contamination. For example, the figure below is from this database, and to it has been added lines and text by P.C. Johnson

### (2011, presentations) to point out th at indoor air concentrations of concern have been observed across the full concentration range of interest for chlorinated solvent sites:

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08Indoor Air Concentration (ug/m3) EPA Data (IA > RL)

Alpha = 1.0

Alpha = 1E-1

Alpha = 1E-2

Alpha = 1E-3

Alpha = 1E-4

Alpha = 1E-5

Groundwater Vapor (ug/m3) 

### U.S. EPA’s Vapor Intrusion Database: Preliminary Evaluation of Attenuation Factors

0.1 – 10 ppb

v OSWER Draft - March 4, 2008 - http:/ /iavi.rti.org/OtherDocuments.cfm

10 – 10,000 μ g/L in ground water



### With respect to (2), the approach ignores the deba te and recent technical advances regarding the utility of sub-slab soil gas samples for pathway assessment. It has been shown at a field study site in Utah that
indoor air sources can cause sub-slab contaminan t vapor plumes; thus, the nearly 1:1 correlation
between indoor air and sub-slab soil gas detections is not validati on that sub-slab samples are good indicators of vapor intrusion as stated above (as 1: 1 correlation would occur w ith indoor sources as well).

There are also field study results showing temporal and spatial variability in sub-slab soil gas samples and experience that sub-slab sampling may not even ha ve been done for pathway assessment by the time that HRS calculations are being done.

### 4. Multi-story and multi-tenant structures Background: In the current HRS, multi-sto ry and mu lti-tenant buildings are evaluated based on population associated with an actually or potentially impacted target . In the ground water pathway, all residents who are served by a well ar e considered subject to the actual or potential contamination of the well. In the air pathway, all resi dents who have an opportunity to br eathe ambient air are considered subject to the actual or potential contamination of the ambient environment within a distance category. All receptors within a contaminated surface water st retch are subject to the level of contamination
associated with that surface water stretch. In the so il exposure pathway, receptors must be able to come
in contact with areas of contamination. In determin ing the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/u se areas within a 200 foot areal extent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multistory (the assumption being that is reasonable for people to use th e outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story/ multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenan t/multi-story building. EPA is proposing to consider all receptors exposed to actual cont amination as the population inhabiting the floor of the intruded space and the population inhabiting the fl oor above and the floor below th e intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, wh ile also minimizing the potentia l for over counting (Figure 3).

### Figure 3 Charge Question #4: When calculating waste quant ity and population, is it scien tifically reasonable for populations in multi-sto ry or multi-tenant structures to be evaluated based on using only the population inhabiting the intruded space and the population on th e floor above and below the intruded space (For example, if contamination is f ound on the first floor, population from the basement and second floor
would be used in the calculation. If contamination is found on the fift h floor, population from the fourth
floor and sixth floor would be used in the calculation – for further e xplanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, wh at alternative approach would you recommend?

It is not clear why possible exposur es in the lowest floors (closest to the vapor source) would ever be discounted? Otherwise, I have no comments on this appr oach as I have little exper ience with impacts in multi-story buildings to draw from at this point in time. It is diffic ult to imagine many scenarios where this issue will be a determining factor in HRS calculations.

### 5. Factor Value for Workers Background: In the current HRS, for the resident popul ation threat of the soil exposure pathway, a
factor value for workers is assi gned based on the total num ber of workers present within the area of
observed contamination. These fact or values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker f actor value in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). Howe ver, since it is anticip ated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamina tion, EPA is proposing to assign workers exposed to subsurface intrusion a higher weighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to subsurface in trusion within the workplace than it is for workers exposed to outdoor surface contamin ation at the workplace? If no, please explain.

This seems to be a comparison of apples and oranges (indoor vapor inhalation vs. outdoor soil exposure), so assuming some fixed correlati on between the two would be inappropriate.

It might be reasonable to assume that worker inhalation risks would be less than those of residents in homes in similar conditions because of differences in exposure durations. The type of work might affect both the building ventilation and worker breathing rates, so indoor conc entration rates might be lower and inhalation higher in more industrial setti ngs vs. office and resi dential settings.

### Paul C. Johnson, Ph.D.

Dept. of Civil and Environ mental Engineering Office of the Dean Ira A. Fulton School of Engineering Ira A. Fulton School of Engineering
P.O. Box 875506 P.O. Box 879309 Arizona State University Arizona State University Tempe AZ 85287-5506 Tempe AZ 85287-9309 (480) 965-9115 (phone) (480) 965-9115 (phone) (480) 965-8293 (FAX) (480) 965-8 855 (FAX) paul.c.johnso n@asu.edu paul.c.johnson@asu.edu

Home Address: 11030 N. Roy al Ct., Fountain Hills, AZ; (480) 837-2005

Area of Expertise: Recognized for contributions to the fields of soil and groundwater remediation and risk assessment; more specifically, the design, monito ring, and optimization of soil and groundwater remediation systems and the monitoring and modeling of human exposure pathways. Much of this work forms the basis for current practice for the most wi dely applied technologies and for federal and state regulatory guidance in the area of risk and exposure assessment.

Education: 1987 Ph.D. - Princeton Univer sity - Chemical Engineering 1984 M.A. - Princeton University - Chemical Engineering 1983 B.S. - University of California, Davis - Chemical Engineering

Academic and Administrative Experience: 2011 – present Ira A. Fulton Schools of Engineering, Dean 2006 – 2011 Ira A. Fulton Schools of Engineering, Executive Dean 2006 – 2007 Ira A. Fulton School of Engineering, Executive and Interim Dean 2004 – 2006 ASU Associate Vice President – Research 2003 – 2004 Ira A. Fulton School of Engineering, Associate Dean – Research 2002 – 2003 College of Engineering and App lied Science Interi m Associate Dean - Research 2000 – present Assistant Chair – Graduate Programs Dept. of Civil and Environmental Engineering

2003 – present Professor, Arizona State University 1997 - 2003 Associate Professor, Arizona State University (tenured) 1994 - 1997 Associate Professor, Arizona State University (untenured)

Industrial Experience: 1994 – present Consultant to industr y and federal and state agencies 1993 - 1994 Senior Research Engi neer, Shell Development, Houston 1990 - 1993 Research Engineer, Shell Development, Houston 1987 - 1990 Associate Research Engi neer, Shell Development, Houston

Other: 2003 – 2011 Editor-In-Chief, National Ground Water Association Journal – Ground Water Monitoring and Remediation

2010 – present National Research Council Committee on Future Options of the Nation’s Subsurface Remediation EffortAwards & Honor Societies: National Ground Water Association Keith E. Anderson Award 2011 Strategic Environmental Research and Development Program (SERDP) Project of the Year 2011 Outstanding Educator (AZ Society of Professional Engineers) 2011 2006 AEHS Academic Career Recognition Award 2006 ASCE/CERF Charles Pankow Award for Innovation Finalist 2005 White House Closing the Circle Award Winner 2003 National Pollution Prevention Roundtable Most Valuable Pollution Prevention Project Award 2003 ASCE/CERF Charles Pankow Award for Innovation Finalist 2003 Environmental Security Technology Certification Program (ESTCP) Project of the Year 2002 ASU College of Engineering Teaching Excellence Award 2002 CEAS Alumni SOAR Outstanding Faculty Advisor Award 2002 National Ground Water Association (NGWA) 2001 Outstanding Ground Water Remediation Project Award 2001 ASCE Journal of Environmental Engineering Editor’s Award 2001 AWPCA Quentin Mees Research Award (w/C. Bruce) 2000 ASU Parents Association Teacher of the Year Finalist 2000 ASU College of Engineering Teaching Excellence Award 1998 ASCE Student Chapter Best Teacher Award 1996 AWPCA Quentin Mees Research Award 1995 NGWA/API National Conference Best Paper 1994 Shell Oil Company Recognition Award 1990, 1991, 1993, 1994 Princeton University Wallace Memorial Fellowship in Engineering 1986-1987 University of California Stauffer Chemical Scholarship 1983 University of California ARCO Scholarship 1982 American Military Engineers Scholarship 1982 Associate Western Universiti es DOE Research Fellowship 1981 Phi Kappa Phi - National Honor Society Tau Beta Pi - National Engineering Honor Society Pi Mu Epsilon - National Mathematics Honor Society

Patents

1. Salanitro, J.P., P.C. Johnson, S.M. Stearns, P.M. Maner, J.H. Miller, and G.E. Spinnler. 2004. In Situ method and Apparatus for Biodegradation of Alkyl Ethers and Tertiary Butyl Alcohol . U.S. Patent 6,808,632.

2. Salanitro, J.P., P.C. Johnson, S.M. Stearns, P.M. Maner, J.H. Miller, and G.E. Spinnler. 2004. In Situ method and Apparatus for Biodegradation of Alkyl Ethers and Tertiary Butyl Alcohol . U.S. Patent 6,776,910 B2.

3. Salanitro, J.P., P.C. Johnson, S.M. Stearns, P.M. Maner, J.H. Miller, and G.E. Spinnler. 2003. In Situ method and Apparatus for Biodegradation of Alkyl Ethers and Tertiary Butyl Alcohol . U.S. Patent 6,503,395 B1.4. Marsden, A.R. Jr., D.A. Weingaertner, L.W.R. Dicks, A.L. Otermat, P.C. Johnson. 1997. Enhanced Deep Soil Vapor Extraction Process and Apparatus Utilizing Sheet Metal Pilings . U.S. Patent 5,660,500.

5. Johnson, P.C.. 1993. In Situ Soil Heating Press/Vapor Extraction System . U.S. Patent 5,244,310.

6. Johnson, P.C., D.A. Weingaertner, L.W.R. Dicks, A.L. Otermat, and A.R. Marsden, Jr.. 1993. Enhanced Deep Soil Vapor Extr action Process and Apparatus for Removing Contaminants Trapped
in or Below the Water Table . U.S. Patent 5,271,693.

7. Dicks, L.W.R., P.C. Johnson, A.R. Marsden, Jr., D.A. Weingaertner. 1993. Modified Heater for In Situ Soil Heating . U.S. Patent 5,233,164.

8. Marsden, A.R., A.L. Otermat, D.A. Weingaertner, P.C. Johnson, L.W.R. Dicks, H.B. Wilde. 1993. Heater Blanket for In Situ Soil Heating . U.S. Patent 5,221,827.

9. Johnson, P.C. and D.A. Weingaertner. 1993. In Situ Thermal Desorption of Contaminated Surface
Soil . U.S. Patent 5,193,934.

10. Johnson, P.C. and D.A. Weingaertner. 1992. In Situ Soil Decontamination Process With Subsurface Vapor Recovery . U.S. Patent 5,169,263.

11. Johnson, P.C., J.D. Colthart, A.L. Otermat, D.A. Weingaertner, C.C. Chou, D.L. Byers, S.M. Stearns, A.R. Marsden Jr., and G.M. D eeley. 1992. Soil Decontamination . U.S. Patent 5,114,497.

12. Johnson, P.C., A.L. Otermat, and C.C. Chou. 1991. In Situ Decontamination of Spills and Landfills by Focused Microwave/Radio Frequency Heati ng and a Closed-Loop Vapor Flushing and Vacuum Recovery System . U.S. Patent 5,076,727.

P UBLICATIONS AND P RESENTATIONS

Refereed Archival Journal Papers:

1. Kingston, J.T, P.R. Dahlen, and P.C. Johnson. 2010. State of the Practice Review of In Situ Thermal Technologies. Ground Water Monitoring and Remediation. 30 (4). 64 – 72.

2. Lesser, L.E., P.C. Johnson, G.E. Spinnler, C.L. Bruce, and J.P. Salanitro. 2010. Spatial Variation in MTBE Biodegradation Activity of Aquifer Solids Sa mples Collected in the Vicinity of a FlowThrough Aerobic Biobarrier. Ground Water Monito ring and Remediation. 30 (2). 63 – 72.

3. Johnson, P.C., C.L. Bruce, K.D. Miller. 2010. A Practical Approach to the Design, Monitoring, and Optimization of In Situ MTBE Aerobic Biobarriers. Ground Water Monitoring and Remediation. 30 (1). 58-66.

4. Luo, H., P. Dahlen, P.C. Johnson, T. Peargin, an d T. Creamer. 2009. Spatial Variability of SoilGas Concentrations near and beneath a Build ing Overlying Shallow Petroleum Hydrocarbon– Impacted Soils. Ground Water Monitoring and Remediation. 29 (1). 81-91.5. Johnson, P.C., R.A. Ettinger, J.P. Kurtz, R. Bryan, and J.E. Kester. 2009. Empirical Assessment of Ground Water–to-Indoor Air Attenuation Factor s for the CDOT-MTL Denver Site.Ground Water Monitoring and Remediation. 29 (1). 153-159.

6. McAlary, T. and P.C. Johnson. 2009. Va por Intrusion. Ground Water Monitoring and Remediation. 29 (1). Editorial.

7. Lesser, L.E, P. C. Johnson, R. Aravena, G.E. Spinnl er, C.L. Bruce, and J.P. Salanitro. 2008. An Evaluation of Compound-Specific Isotope Analyses for Assessing the Biodegradation of MTBE at Port Hueneme, CA. Environmental Science and Technology.42 (17). 6637–6643.

8. Odencrantz, J.E., H. O’Neill, S.J. Steinmacher, J. D. Case, and P.C. Johnson. 2008. Residential Vapor Intrusion Evaluation: Long-Duration Passive Sampling vs. Short-Duration Active Sampling. Remediation. Autumn. 49-54.

9. Lundegard, P.D., P.C. Johnson, and P. Dahlen. 2008. Oxygen Transport from the Atmosphere to Soil Gas Beneath a Slab-on-Grade Foundation Over lying Petroleum-Impacted Soil. Environmental Science and Technology.42 (15). 5534–5540.

10. Xu, Y., L.A. Baker, and P.C. Johnson. 2007. Tre nds in Groundwater Nitrate Contamination in the Phoenix, Arizona, USA Region. Ground Water Monitoring and Remediation. 27 (2). 49 – 56.

11. P.Lundegard, P.D., P.C. Jo hnson, an d Z. Liu. 2006 . Source Zone Natural Attenuation at Petroleum Hydrocarbon Spill Sites – I: Site-Specific Ass essment Approach. Ground Water Monitoring and Remediation.26 (4). 82 – 92.

12. Johnson, P.C., P.D. Lundegard, and Z. Liu. 2 006. Source Zone Natural Attenuation at Petroleum Hydrocarbon Spill Sites – II: Application to Source Zones at a Former Oil Production Field. Ground Water Monitoring and Remediation.26 (4), 93–106

13. Abreu, L. and P.C. Johnson. 2005. Abreu, L. D. V. and P.C. Johnson. Modeling the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into Buildings - Influence of Degradation Rate, Source Concentration, and Depth. Environmental Science and Technology. 40 (7). 2304-2315.

14. Abreu, L. and P.C. Johnson. 2005. Effect of Vapor Source-Building Separation and Building Construction on Soil Vapor Intrusion as Studied with a Three-Dimensional Numerical Model. Environmental Science and Technology. 39 (12). 4550-4561.

15. Johnson, P.C.. 2005. Sensitivity Analysis and Iden tification of Critical and Non-Critical Parameters for the Johnson and Ettinger Vapor Intrusion Model. Ground Water Monitoring and Remediation Winter 2005.25 (1). 63-78.

16. Vangelas, K., F.H. Chapelle, J. Cummings, P.C. Johnson, K.A. Lovelace, E.K. Nyer, R. Norris. 2005. Monitored Natural Attenuation Forum: A Panel Discussion on the Use of Integrated Mass
Flux and MNA Inconsistencies Within Federal and State Agencies. Remediation. 16 (1). 141 -152.

17. Lundegard, P.D. and P.C. Johnson. 2004. A Composite Plume Approach for the Analysis of Dissolved Contaminants in Ground Water vers us Distance from Source Areas. Ground Water Monitoring and Remediation. Summer 2004. 24 (3). 69 - 75.

18. Sigley, J.L., P.C. Johnson, and S.P. Beaudoin. 2003. Use of Nonionic Surfactant to Reduce Sulfuric Acid Mist in the Copper Electrowinning Process. Hydrometallurgy. 70 (2003). 1 – 8.19. Hers, R. Zapf-Gilje, P. C. Johnson , and L. Li. 2002. Evaluation of the Johnson and Ettinger Model for Prediction of Indoor Air Quality. Ground Wate r Monitoring and Remediation. 23 (2). 119 –
133.

20. Amerson, I.L., C.L. Bruce, P.C. Johnson, a nd R.L. Johnson. 2001. A Multi-Tracer Push-Pull Diagnostic Test for In Situ Air Sparging Syst ems. Bioremediation Journal, 5(4):349-362.

21. Bruce, C.L., I.L. Amerson, R.L. Johnson, and P. C. Johnson. 2001. Use of an SF6-Based Diagnostic Tool for Assessing Air Distributions and Oxyge n Transfer Rates during IAS Operation. Bioremediation Journal, 5(4):337-347.

22. Johnson, P.C., A. Leeson, R.L. J ohnson, C.M. Vogel, R.E. Hinchee, M. Marley, T. Peargin, C.L. Bruce, I.L. Amerson, C.T. Coonfare, and R.D. Gillespie. 2001. A Practical Approach for the Selection, Pilot Testing, Design, and Monitoring of In Situ Air Sparging/Biosparging Systems. Bioremediation Journal, 5(4):267-281.

23. Johnson, P.C., R.L. Johnson, C.L. Bruce, and A. Leeson. 2001. Advances in In Situ Air Sparging/Biosparging. Bioremediation Journal, 5(4):251-266.

24. Johnson, R.L., P.C. Johnson, T.L. Johnson, and A. Leeson. 2001. Helium Tracer Tests for Assessing Contaminant Vapor Recovery and Air Distribution During In Situ Air Sparging. Bioremediation Journal, 5(4):321-336.

25. Johnson, R.L., P.C. Johnson, T.L. Johnson, N.R. T homson, and A. Leeson. 2001. Diagnosis of In Situ Air Sparging Performance Using Transient Groundwater Pressure Changes During Startup and Shutdown. Bioremediation Journal, 5(4):299-320.

26. Johnson, R.L., P.C. Johnson, I.L. Amerson, T.L. J ohnson, C.L. Bruce, A. Leeson, and C.M. Vogel. 2001. Diagnostic Tools for Integrated In Situ Air Sparging Pilot Tests. Bioremediation Journal, 5(4):283-298.

27. Abranovic, D., P. C. Johnson, R. J. Charbeneau, and T. Hemstreet. 2000. A Graphical Approach for Determining Dilution-Attenuati on Factors: Basic Theory and Approach for Submerged Sources. Groundwater Monitoring and Remediation.

28. Salanitro, J. P., P. C. Johnson, G. E. Spinnler, P. M. Maner, H. L. Wisniewski and C. L. Bruce. 2000. Field-Scale Demonstration of Enhan ced MTBE Bioremediation through Aquifer Bioaugmentation and Oxygenation. E nvironmental Science and Technology. 34 (19). 4152-4162

29. Johnson, P.C., A. Das, and C. Bruce. 1999. Effect of Flowrate Changes and Pulsing on the Treatment of Source Zones by In Situ Air Sparging. Environmental Science and Technology. 33 (10). 1726-1731.

30. Johnson, P.C., R.L. Johnson, and M.W. Kemblows ki. 1999. Assessing the Significance of Vapor Migration to Enclosed-Spaces on a Site-Specific Basi s. Journal of Soil Contamination. 8 (3). 389 -
421.

31. Johnson, P.C., C. Bruce. R.L. Johnson, and M.W. Kemblowski. 1998. In Situ Measurement of Effective Vapor-Phase Porous Medium Diffusion Coefficients. Environmental Science and Technology. 32. 3405-3409.32. Johnson, P.C.. 1998. An Assessment of the Contributions of Volatilization and Biodegradation to In Situ Air Sparging Performance. Environmen tal Science and Technology. 32 (2). 276-281.

33. Rutherford, K..W., D.H. Bass, W., W. McPhee, P.C. Johnson. 1997. Estimation of Oxygen Mass Transfer Coefficients During Air Sparging. Bioremediation. 4 (1). 153-158.

34. Johnson, P.C., R.L. Johnson, C. Neaville, E.E. Han sen, S.M. Stearns, and I.J. Dortch. 1997. An Assessment of Conventional In Situ Air Sparging Tests. Ground Water. 35 (5). 765 - 774.

35. Rutherford, K.W. and P.C. Johnson. 1996. Effects of Process Control Changes on Aquifer Oxygenation Rates During In Situ Air Spargi ng in Homogeneous Aquifers. Ground Water Monitoring and Remediation. 16 (4). 132 - 141.

36. Johnson, P. C. and R. A. Ettinger. 1994. Some Considerations for the Design of In Situ Vapor Extraction Systems: Radius of Influence -vs- Radius of Remediation. Ground Water Monitoring and Remediation. 14 (3). 123 - 128.

37. Johnson, R.L., P.C. Johnson, D.B. McWhorter, R. Hinchee, and I. Goodman. 1993. An Overview of In Situ Air Sparging. Ground Water Monitoring and Remediation. 13 (4). 127 - 135.

38. Benson, D.A., D. Huntley, and P.C. Johnson. 1993. Modeling Vapor Extraction and General Transport in the Presence of NAPL Mixtures and Nonideal Conditions. Groundwater. 31 (3). 437 -
445.

39. Johnson, P.C. and R.A. Ettinger. 1991. Heuristic Model for the Intrusion Rate of Contaminant Vapors Into Buildings. Environ. Sci. Technol.. 25(8). 1445-1452.

40. Johnson, P.C., C.C. Stanley, M.W. Kemblowski, D.L. Byers, and J.D. Colthart. 1990. A Practical Approach to the Design, Operation, and Monitoring of In Situ Soil-Venting Systems. Ground Water Monit. Rev.. 10 (2). 159 - 178.

41. Johnson, P.C., M. W. Kemblowski, and J. D. Colthart. 1990. Quantitative Analysis for the Cleanup of Hydrocarbon-Contaminated Soils by In Situ Soil Venting. Ground Water. 3 (28):413-
429.

42. Johnson, P.C., P. Nott, and R. Jackson. 1990. Friction-Collisional Equations of Motion for Particulate Flows and Their Application to Chutes. J. Fluid Mech.. 210. 501-535.

43. Johnson, P.C. and R. Jackson. 1987. Fricti on-Collisional Constitutive Relations for Granular Materials, with Application to Plane Shearing. J. Fluid Mech.. 176. 67-93.

44. Johnson P.C., M.C. Lagunas-Solar, and M.J. Avila. 1984. The Indirect Production of No-CarrierAdded 57 Co via the 59 Co(p,3n) 57 Ni-> 57 Co Reaction. Int. J. Applied Radiat. Isot. 35(5). 371-
376.

45. Lagunas-Solar, M.J. Avila, and P.C. Johnson P.C.. 1984. Cyclotron Production of 101m Rh via

Proton-Induced Reactions on 103 Rh Targets. Int. J. Applied Radiat. Isot. 35(8). 743-748.46. Lagunas-Solar, M.C., M.J. Avila, N.J. Navarro, a nd P.C. Johnson. 1983 . Cyclotron Production of

No-Carrier-Added 97 Ru by Proton Bombardment of 103 Rh Targets. Int. J. Applied Radiat. Isot. 34(6). 915-922.

Other Peer-Reviewed Reviewed Publications:

1. Johnson P.C., R.L. Johnson, C.L. Bruce CL. 2010

. In Situ Air Sparging for the Treatment of Dissolved Hydrocarbon Groundwater Plumes. In Stroo HF, Ward CH, eds, In Situ Rem ediation of Chlorinated Solvent Plumes, Vol 2, SERDP/ESTCP Remediation Technology Monograph Series. Springer Science+Business Media, LLC, New York, NY, USA, In Press.

2. Johnson R.L. and P.C. Johnson. 20 10. In Situ Sparging for the Delivery of Gases in the Subsurface. In Kitanidis, P.K. and P.L. McCarty eds, Delivery and Mixing in the Subsurface: Processes and Principles for In Situ Remediation. SERDP/ESTCP Remediation Technology Monograph Series. Springer Science+Business Media, LLC, New York, NY, USA, In Press.

3. McAlary, T., R.A. Ettinger, P.C. Johnson, B. Eklund, H. Hayes, D.B. Chadwick, I. Rivera-Duarte. 2009. Review of Best Practices, Knowledge and Data Gaps, and Research Opportunties for the U.S. Department of Navy Vapor Intrusion Focus Areas. Technical Report 1982. May. SPAWAR Systems Center Pacific.

4. Hay- Wilson, L., P. C. Johnson, and J. Rocco. 200 5. Collecting and Interpreting Soil Gas Samples
from the Vado se Zone: A Practical Strategy for Assessing the Subsurface-Vapor-to-Indoor-Air Migration Pathway at Petroleum Hy drocarbon Sites. American Petroleum Institute. Publication
Number 4741. November.

5. McAlary, T., R.A. Ettinger, and P.C. Johnson. 2005. Reference Handbook for Si te-Specific Assessment of Subsurface Vapor Intrusion to Indo or Air. EPRI Technical Report 1008492. Palo Alto, CA.

6. Johnson, P.C.., K. Miller, and C. L. Bruce. 2004. A Pr actical Approach to the Design, Monitoring, and Optimization of In Sit u MTBE Aerobic Biobarriers. http://docs.serdpestcp.org/viewfile.cfm?D oc=CU0013%2DTR%2D01%2Epdf

.

7. Johnson, P.C.., K. Miller, and C. L. Bruce. 2004. In Situ Bioremediation of MTBE in Groundwater – Final Technical Repo rt.http://docs.serdp

estcp.org/viewfile.cfm?Doc=C U%2D0013%2DFR%2D01%2Epdf.

8. Johnson, P.C.., K. Miller, and C. L. Bruce. 2004. In Situ Bioremediation of MTBE in Groundwater – Cost and Performance Report. http://www. estcp.org/documents /tech docs/CU-0013.pdf

.

9. Johnson, P.C., P.D. Lundegard, J. Catts, D. Eley, K. Schroeder, E. Nichols, David Peterson. 2004. Dissolved Total Petroleum Hydrocarbons (TPH) Groundwater Plume Stability at the Former Guadalupe Oil Field.10. Johnson, P.C., P.D. Lundegard, J. Catts, K. DiSi mone, D. Eley, K. Schroeder. 2003. Source Zone Natural Attenuation Field Measurements, Data In terpretation, and Data Reduction at the Former Guadalupe Oil Field (Version 2.1). Ratified December 18.

11. Roggemans, S., C.L. Bruce, and P.C. Johnson. 20 02. Vadose Zone Natural Attenuation of Hydrocarbon Vapors: An Empirical Assessment of Soil Gas Vertical Profile Data. American Petroleum Institute Technical Report.

12. Spinnler, G.E., P.C. Johnson, K. Miller. 2002 . Bioaugmentation Field Testing for MTBE
Treatment. USEPA Ground Water Currents. October. Issue 41.

13. Johnson, P.C.. 2002. Sensitivity Analysis and Iden tification of Critical and Non-Critical Parameters for the Johnson and Ettinger (1991) Vapor Intrusion Model. American Petroleum Institute Technical Report.

14. Johnson, P.C., R.A. Ettinger, J. Kurtz, R. Bryan, and J.E. Kester. 2001. Empirical Assessment of Subsurface Vapor –to- Indoor Air Attenuation Fact ors and Comparison with Theory for the CDOTMTL Denver Site. American Petroleum Institute Technical Report.

15. Johnson, P.C., M. W. Kemblowski, and R.L. Johnson. 1998. Assessing the Significance of Subsurface Contaminant Migration to Enclosed Spaces: Site-Specific Alternatives to Generic
Estimates. American Petroleum Institute Publication No. 4674. December.

16. Johnson, P.C., D. Abranovic, R.J. Charbeneau, and T. Hemstreet. 1997. Technical Background Document for the Graphical Approach for Determ ining Site-Specific Dilution-Attenuation Factors (DAFs). American Petroleum Institute Publication 4659.

17. Johnson, P.C., D. Abranovic, R.J. Charbeneau, and T. Hemstreet. 1997. User’s Guide for the Graphical Approach for Determining Site-Specific Dilution-Attenuation Factors (DAFs). American
Petroleum Institute Publication 4659.

18. American Society for Testing and Materials. 1997. Standard Guide for Risk-Based Corrective Action (RBCA) at Chemical Release Sites.

19. Johnson, P.C.. 1997. Application of Risk-Based Corrective Action at a Petroleum Release Site. United States Environmental Protection Agency.

20. American Society for Testing and Materials (P.C. Johnson lead author). 1995. Standard Guide for Risk-Based Corrective Action (RBCA) at Petroleum Release Sites. E1739-95 (updated and modifed version of ASTM ES-38 below).

21. American Society for Testing and Materials (P.C. Johnson lead author). 1994. Emergency Guide for Risk-Based Corrective Action (RBCA) at Petroleum Release Sites. ES-38.

Books, Book Chapters, M onographs, and Dissertations:

1. Johnson P.C., R.L. Johnson, C.L. Bruce CL. 2010. In Situ Air Sparging for the Treatment of Dissolved Hydrocarbon Groundwater Plumes. In Stroo HF, Ward CH, eds, In Situ Remediation ofChlorinated Solvent Plumes, Vol 2, SERDP/ESTCP Remediation Technology Monograph Series. Springer Science+Business Media, LLC, New York, NY, USA, In Press.

2. Johnson R.L. and P.C. Johnson. 2010. In Situ Sparging for the Delivery of Gases in the Subsurface. In Kitanidis, P.K. and P.L. McCarty eds, Delivery and Mixing in the Subsurface: Processes and Principles for In Situ Remediation. SERDP/ESTCP Remediation Technology Monograph Series. Springer Science+Business Media, LLC, New York, NY, USA, In Press.

3. Johnson, P.C. 2000. Chapter 14: Aquifer Restoration via In Situ Air Sparging. In Standard Handbook of Environmental Science, Health, and Technology (J. Lehr, ed.). McGraw-Hill.

4. Johnson, P.C.. 1999. Chapter 23: Hydraulic D esign for Groundwater Contamination. Hydraulic Design (L. Mays, ed.). McGraw-Hill. 23.1 – 23.68.

5. Dablow, J.F., J.A. Pearce, P.C. Johnson. 1998. Steam and Electro-Heating Remediation of Tight
Soils . Ann Arbor Press.

6. Johnson, P. C. and R. A. Ettinger. 1997. Some Considerations for the Design of In Situ Vapor Extraction Systems: Radius of Influence -vs- Radius of Remediation. Subsurface Restoration (C.H. Ward, J.A. Cherry, M.R. Scalf, editors). Ann Arbor Press. 209 - 216.

7. Hinchee, R.L., R.N. Miller, and P.C. Johnson. 1995. In Situ Aeration: Air Sparging, Bioventing,
and Related Remediation Processes. Battelle Press. ISBN 1-57477-003-9.

8. Johnson, P.C., G.E. Hoag, R.H. Hinchee, R.A. Brown, and A.L. Baehr. 1994. Innovative Site Remediation Technology: Vapor Extraction-Based Technologies (Soil Vapor Extraction, Bioventing, Air Sparging, and Thermally-Enhanced Soil Vapor Extraction). USEPA/AAEE WASTECH Monograph. ISBN 1-883767-08-3.

9. Johnson, P.C. and A.J. Stabenau. 1991. HyperVen tilate - A Software Guidance System Created for Vapor Extraction Applications - Users Manual . USEPA 600/R-93/028.

10. Johnson, P.C., R.L. Johnson, C. Neaville, E.E. Han sen, S.M. Stearns, and I.J. Dortch. 1995. Do Conventional Practices Indicate In Situ Air Sparging Performance?. In Situ Aeration: Air Sparging, Bioventing, and Related Remediation Processes (Hinchee, Miller, Johnson, eds.). Battelle Press. 1 -
20.

11. Bedient P.B. and P.C. Johnson. 1992. Soil Va por Extraction Systems. Groundwater Remediation

. Charbeneau, R.J., P.B. Bedient, and R.C. Loehr Eds.. Technomic Publishing Inc.. 143-160.

12. Johnson, P.C., C.C. Stanley, D.L. Byers, D.A. Benson, and M.A. Acton. 1991. Soil Venting at a
California Site: Field Data Reconciled with Theory. Hydrocarbon Contaminated Soils and Groundwater: Analysis, Fate, Environmental and Public Health Effects, Remediation, Vol I." P.T. Kostecki and E.J. Calabrese (eds.). Lewis Publishers. 253 - 282.

13. Rixey, W.G., P.C. Johnson, G.M. Deeley, D.L. Byers, and I.J. Dortch. 1991. Mechanisms for the Removal of Residual Hydrocarbons for Soils by Water, Solvent, and Surfactant Flushing. In Petroleum Contaminated Soils Volume 4 (P.T. Kost ecki and E.J. Calabrese Eds.). Lewis Publishers.14. Johnson, P.C., Hertz, M.B. and D.L. Byers. 1990 . Estimates for Hydrocarbon Vapor Emissions Resulting from Service Station Remediations a nd Buried Gasoline-Contaminated Soils. In Petroleum Contaminated Soils Volume 3 (P.T. Kosteck i and E.J. Calabrese Eds.). Lewis Publishers.
295-326.

15. Johnson, P.C.. 1987. Fricti onal-Collisional Relationships fo r Particulate Flows and Their Application to Plane Shear Flows. Ph.D. Thesis. Department of Chemical Engineering. Princeton University

Invited Presentations/Papers:

1. Johnson, P.C., P. Dahlen, H. Luo, C. Holton, K. Gorder, E. Dettenmaier. 2011. Temporal Changes
in VI Behavior:Considerations for Pathwa y Assessment. U. Washington/USEPA Superfund Research Center. June 15. Seattle, WA.

2. Johnson, P.C., P. Dahlen, H. Luo, C. Holton, K. Gorder, E. Dettenmaier. 2011. Temporal Changes in VI Behavior:Considerations for Pathway Assess ment. 21at Annual Training Program – National Association of Remedial Program Managers. May 16-20. Kansas City, MO.

3. Johnson, P.C. and E. Nichols. 2011. Session Keynote: Measurement and Control of Subsurface Contaminant Discharge and Its Use in Decision-Making. RemTEC Summit. May 16-19. Chicago,

IL.

4. Kavanaugh, M., K. Pennell, Johnson , P.C., and Anna Willett. 2011. Panel Discussion -Future of
Subsurface Remediation Efforts in the United Stat es: Barriers to Success. RemTEC Summit. May 16-19. Chicago, IL.

5. Johnson, P.C. 2011. Soil and Groundwater Re mediation: Issues, Advances, and Challenges. Engineers Club of the West Valley. April. Sun City, AZ.

6. Johnson, P.C., P. Dahlen, H. Luo, C. Holton. 2011. Temporal Changes in VI Behavior:Considerations for Pathway Assessmen t. USEPA Workshop on Addressing Regulatory Challenges in Vapor Intrusion: A State of the Science Update Focusing on Chlorinated VOCs.
AEHS 21 st Annual Meeting and West Coast Conference on Soils, Sediments, Water. San Diego, CA.

7. Johnson, P.C. 2010.Session Keynote: Vapor Intrusio n Pathway Assessment: State of the Practice and Opportuntites for v3.0. SERDP/ESTCP Partners Conference. December, 2010.

8. Johnson, P.C., P. Dahlen, H. Luo, C. Holton, K. Gorder, E. Dettenmaier. 2011. Integrated Fieldscale, Lab-scale, and Modeling Studies for Improving Our Ability to Assess the Groundwater to Indoor Air Pathway. SERDP Technical Exchange Meeting on Vapor Intrusion. August 16 - 17. Salt Lake City, UT.

9. Johnson, P.C. 2010.Vapor Intrusion Pathway Assess ment: Challenges, Developments, and Ongoing Research. Air Force Restoration and Technology Transfer Workshop. April 6 – 8, 2010.10. Johnson, P.C. 2009. Subsurface Vapor to Indoor Ai r Pathway: Consideration of Multiple Lines of Evidence in Pathway Assessment. . CA Department of Toxic Substances Control (DTSC), Asilomar,
CA. November.

11. Johnson, P.C. 2008. Aeration-Based Remedi ation Technologies. Remediation Technology Symposium. CA Department of Toxic Substa nces Control (DTSC). Sacramento. May 14 – 16.

12. Johnson, P.C., J. Triplett-Kingston, P. Dahlen, E. Foote, S. and Williams. 2008. Critical Evaluation of In Situ Thermal Treatment Technologies for DNAPL Source Zone Treatment. 2008 AFCEE Technology Transfer Workshop. March 25-28, 2008.

13. Johnson, P.C. 2008. The Path to More Confid ent and Cost-Effective Vapor Intrusion Pathway
Assessment. 18 th Annual AEHS Meeting and International Conference on Soils, Sediments & Water. San Diego. March 10 - 13.

14. Johnson, P.C. and R.A. Ettinger. 2008. An Empi rical Analysis of Data From the Colorado DoT Materials Laboratory Testing Site, Denver CO. 18 th Annual AEHS Meeting and International Conference on Soils, Sediments & Wate r. San Diego. March 10 - 13.

15. Johnson, P.C., 2007. Vapor Intrusion – Conceptu alizing and Dealing with Spatial and Temporal Variability. Air and Waste Management Associa tion: Vapor Intrusion – A Rapidly Developing Environmental Challenge. November 13 – 15, 2007.

16. Dahlen, P. and P.C. Johnson. 2007. Field Comparison of Oxygen Delivery Technologies. University Consortium for Field-Focused Groundwater Contamination Research. April 17 – 19. Ontario, Canada.

17. Triplett-Kingston, J.. and P.C. Johnson. 2007. Empirical Assessment of Thermal Technology Performance. April 17 – 19. Ontario, Canada.

18. Johnson, P.C.. 2007. Vapor Intrusion Field Studi es and Modeling. April 17 – 19. Ontario, Canada.

19. Johnson, P.C.. 2007. Subsurface Vapor to Ind oor Air Pathway Assessment: Lessons-Learned and Challenges for the Future. Keynote Presentation at the 6 th State of Washington Hydrology Symposium. May 1 – 3.

20. Johnson, P.C.. 2006. Field Studies of Oxygen and Hydrocarbon Vapor Transport Beneath and Around Buildings Located Over NAPL Sources. 16 th Annual AEHS Meeting and International Conference on Soils, Sediments & Wa ter. San Diego. March.

21. Johnson, P.C. 2005. Vapor Intrusion – Lessons Learned Through Numerical Simulation. 15 th Annual AEHS Meeting and International Conference on Soils, Sediments & Water. San Diego. March.

22. Johnson, P.C. and L. D. V. Abreu. 2004. A dvances in the Modeling of Vapor Migration to Buildings. Annual International Conference on So ils, Sediments & Water. University of
Massachusetts. October.23. Johnson, P.C. and L. D. V. Abreu. 2004. A dvances in the Modeling of Vapor Migration to Buildings. Annual International Conference on So ils, Sediments & Water. University of
Massachusetts. October.

24. Johnson, P.C.. 2002. Confusion and Delusion in th e World of Vapor Intrusion. Keynote Speech – First Annual Midwestern States Risk Assessment Sympos ium. July 16 – 17. Indianapolis, Indiana.

25. Johnson, P.C.. 2002. Arizona Groundwater St udy – Preliminary Results. Fourth Annual Underground Storage Tank Program Conference, Ar izona Department of Environmental Quality. June 5. Phoenix, AZ.

26. Johnson, P.C.. 2001. Assessing Risks From Vapor Migration To Enclosed Spaces. Pennsylvania Department of Environmental Protection Annual Conference. June 7. Harrisburg, PA.

27. Johnson P. C.. 2000. Advances in Vapour Intrusion Modelling for Risk-Based Decision Making.
2000 Contaminated Site Remediation Conferen ce. December 4 – 8. Melbourne Australia

28. Johnson, P.C.. 2000. A Retrospective Look to the Future of LUST Issues. Third Annual Underground Storage Tank Program Conference, Ar izona Department of Environmental Quality. September 29. Phoenix, AZ.

29. Johnson, P.C. and R.A. Ettinger. 2000. Pr ogress Towards Gaining a Better Understanding of Subsurface Vapor Migration. RCRA: Visions for the Future Conference. USEPA. August 15 –18. Washington, D.C..

30. Johnson, P.C. and R.A. Ettinger. 2000. An Empi rical Analysis of Data From the Colorado DoT Materials Laboratory Testing Site, Denver CO. RCRA: Visions for the Future Conference. USEPA. August 15 –18. Washington, D.C..

31. Johnson, P.C., C. Bruce, J. P. Salanitro, G. E. Spinnler. 2000. MTBE Biobarrier Studies at Port Hueneme, CA. 2000 National LUST Conference – U. S. Environmental Protection Agency. March. Portland, OR.

32. Johnson, P.C. and J.P. Salanitro. 1999. MT BE Bioremediation. New Jersey Department of Environmental Protection. August 17, 1999. Trenton, NJ.

33. Ward, C.H., P.C. Johnson, and J.B. Hughes. 1999 . Plenary Lecture: Enhanced BioAttenuation for Subsurface Remediation. In Situ and On Site Bioremediation – Fifth International Symposium. April 19-22, 1999. San Diego, CA.

34. Johnson, P.C. 1998. An Introduction to Natural A ttenuation. First National Stakeholders Forum on
Monitored Natural Attenuation. San Francisco. A ugust 31 – September 1. (voted best presentation by attendees)

35. Johnson, P.C.. 1997. Keynote Lecture: Vadose Zone Natural Attenuation - Issues, Modeling Challenges, and Critical Measurements. NGWA Petroleum Hydrocarbons and Organic Chemicals in Groundwater: Prevention, Detection, and Restorati on. November 12 - 14. Houston. (voted best presentation by attendees)36. Johnson, P.C. and R.L. Johnson. 1997. Plenary L ecture: It Looks Good on Paper and You’ve Paid a Bunch, But is Your Remediation System out to Lunch? The Fourth International Symposium - In Situ and On-Site Bioremediation. April 28 - May 1, 1997. New Orleans, LA.

37. Johnson, P.C.. 1997. Keynote Lecture: US Field and Research Experiences with In Situ Air Sparging. ATV Danish National Groundwater C onference. March 11 - 12. Billund, Denmark.

38. Johnson, P.C.. 1997. Conventional and Innovative In Situ Air Sparging Pilot Test Procedures. ATV
Danish National Groundwater Conference. March 11 - 12. Billund, Denmark.

39. Johnson, P.C.. 1996. Risk-Based Corrective Action. Santa Fe Pacific Pipeline Partnership. Los Angeles. August 23.

40. Johnson, P.C.. 1996. Risk-Based Corrective Action Training. USEPA/OUST/ADEQ. Phoenix Arizona. August 15 - 16.

41. Johnson, P.C.. 1996. An Engineer’s Introduc tion to Bioremediation. First Arizona Soil Remediation Conference. Phoenix. May 3.

42. Johnson, P.C.. 1996. Soil Vapor Extraction - Mass Transfer Effects. First Arizona Soil Remediation Conference. Phoenix. May 3.

43. Johnson, P.C.. 1996. Risk-Based Corrective Ac tion for Tribal Lands. USEPA/OUST. Denver
Colorado. March 25 - 29.

44. Johnson, P.C.. 1996. Risk-Based Corrective Ac tion. USEPA/OUST and State of Colorado.
Denver Colorado. March 19 - 22.

45. Johnson, P.C.. 1995. Risk-Based Corrective Action Demonstration Project. USEPA/OUST and West Virginia Department of Environmental Quality. September 28 - 29.

46. Johnson, P.C.. 1995. Hydrocarbon Removal - How Much is Enough? USEPA OUST Strategic Research Planning Meeting. Las Vegas. September 20 - 21.

47. Johnson, P.C.. 1995. Risk-Based Corrective Ac tion for UST Sites. Arizona Department of Environmental Quality. Phoenix. September 18.

48. Johnson, P.C.. 1995. Research Needs for the Remediation of DNAPL Sites. USAF Research Planning Meeting. Tallahasee. August.

49. Johnson, P.C.. 1995. Modeling Biodegradation in Groundwater - Analytical Models. API Biodegradation Modelling Works hop. Dallas. May 8 - 9.

50. Johnson, P.C.. 1995. In Situ Remediation Technologies. Arizona Water Pollution Control
Association. Phoenix. March 17.51. Johnson, P.C.. 1995. Risk-Based Corrective Action. South Dakota Dept. of Environmental Quality.
March 8.

52. Johnson, P.C.. 1995. Aeration-based Remediation Technologies. ARCO Research. Los Angeles. February 7.

53. Johnson, P.C.. 1994. Considerations for the Design and Optimization of Soil Vapor Extraction Systems. Invited presentation at the 1994 AP I/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston.

54. Johnson, P.C., R.L. Johnson, C. Neaville, and E.E. Hansen. 1994. Performance Monitoring and Pilot Testing of In Situ Air Sparging Systems. Invited Presentation at the AGWSE National Education Program. October 9-12. Las Vegas, Nevada.

55. Johnson, P.C.. 1994. Pilot Testing of In Situ Air Sparging Systems. Invited Presentation at the
Annual Air Force Center for Environmental Ex cellence (AFCEE) Conference. San Antonio.

56. Johnson, P.C. and D. Mohr. 1994. Soil Vapor Ex traction, Bioventing, and Air Sparging. Invited presentation at the 1st USEPA Strategic Technology Evaluation Workshop. February.

57. Johnson, P.C.. 1993. Risk-Based Corrective Action: Developments and Opportunities. Presented at the 14th Annual Society of Toxicology and Chemistry Meeting. November 14-18. Houston, TX.

National Conference Proceedings Reviewed Papers, Abstracts, and Presentations:

1. Luo, H., C. Holton, P. Dahlen, and P.C. Johnson. 2011. Field and Modeling Studies of Temporal Variability of Sub-Slab Soil Gas and Indoor Air Concentrations at a House Overlying a Chlorinated Compound-Impacted Groundwater Plume. Bioremediation and Sustainable Environmental Technologies. Reno, NV. June 27-30, 2011.

2. Escobar, E., P. Dahlen, and P.C. Johnson. 2011. Biodegradation of Petroleum Hydrocarbon Vapor Components in the Subsurface: A Laboratory Soil Column Study. Bioremediation and Sustainable Environmental Technologies. Reno, NV. June 27-30, 2011.

3. Escobar, E., P. Dahlen, P. C. Johnson. 2011. Transport and Biodegradation of Petroleum Hydrocarbon Vapor Components in the Subsurface – A Soil Column Study. USEPA Workshop on Addressing Regulatory Challenges in Vapor Intrusion: A State of the Science Update Focusing on
Chlorinated VOCs. AEHS 21 st Annual Meeting and West Coast Conference on Soils, Sediments, Water. San Diego, CA.

4. H. Luo and P. C. Johnson. 2011. Incorporating Ba rometric Pressure and Wind Effects into Vapor Intrusion Simulations. USEPA Workshop on Addr essing Regulatory Challenges in Vapor Intrusion: A State of the Science Update Focusing on Chlorinated VOCs. AEHS 21 st Annual Meeting and West Coast Conference on Soils, Sediments, Water. San Diego, CA.5. Luo. H., P. Dahlen, T. Peargin, P.C. Johnson. 2010. Proof-of-Concept Study of an Engineering Bio-Attenuation Barrier Beneath a Building at a Petroleum Hydrocarbon-Impacted Site.
Remediation of Chlorinated Solvents and Recal citrant Compounds. May 24- 27. Monterey, CA.

6. P.Lundegard, P., P. Johnson, and P. Dahlen. 2008. Oxygen Transport from the Atmosphere to Soil Gas Beneath a Slab-on-Grade Foundation Overlying Petroleum-Impacted Soil. 18 th Annual AEHS Meeting and International Conference on Soils, Sediments & Water. San Diego. March 10 - 13.

7. Spinnler, G.E., P.C. Johnson, L. Lesser, C.L. Bruce, R. Aravena, J.P. Salanitro, R.L. Johnson. 2003, MTBE and TBA Biodegradation Assessment Under Natural and Engineered Conditions Using Compound-Specific Carbon Isotope Analysis at Port Hueneme, CA. NGWA/API Petroleum Hydrocarbons and Organic Chemicals in Groundwater. August 20- 22. Costa Mesa, CA.

8. Johnson, P.C. and L. Abreu. 2003. Learning Thro ugh the Simulation of Vapor Intrusion Scenarios. NGWA/API Petroleum Hyrocarbons and Other Organic Chemicals in Groundwater. August 20 – 22. Costa Mesa, CA.

9. Johnson, P.C., P. Dahlen, E . Henry, and M. Matsum ura. 2003. It’s Not About Plume Lengths – The Arizona Groundwater Study. NGWA/API Petroleum Hyrocarbons and Other Organic Chemicals in Groundwater. August 20 – 22. Costa Mesa, CA.

10. P.C. Johnson, and K. Miller. 2002. Large-S cale Mixed MTBE-BTEX Plume Containment at Port Hueneme, CA, Using A Combination of Biostimula tion and Bioaugmentation. Third International
Conference on Remediation of Chlorinated and R ecalcitrant Compounds. Monterey, CA. May 20 –
23.

11. Bruce, C.L. and P.C. Johnson. 2001. Effect of Chemical Properties on IAS Treatment: An Evaluation of Field and Lab Data Comparing MT BE vs. BTEX Removal. API/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November 14 –
16.

12. Johnson, P. C.. 2001. Gaining a Better Unders tanding of the Johnson and Ettinger Model Through Sensisivity Analysis. API/NGWA Conference: Pe troleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November 14 – 16.

13. Spinnler, G.E., J.P. Salanitro, and P.C. Johnson. 2001. MTBE Remediation at Retail Gas Stations by Bioaugmentation. API/NGWA Conference: Petr oleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November 14 – 16.

14. Salanitro, J.P., P.C. Johnson, C.L. Bruce, Spinnler, G.E., P.M. Maner, D.L. Tharpe, H.L.
Wisniewski. 2001. In Situ Bioremediation of MTBE Using Biobarriers of Single or Mixed Cultures.
In Situ and On-Site Bioremediation – The Sixth Inte rnational Symposium. San Diego. June 4 - 7.

15. Spinnler, G.E., P.M. Maner, J.P. Salanitro a nd P.C. Johnson. 2001. Demonstration of the BioRemedy Process for MTBE Remediation at Reta il Gasoline Stations. In Situ and On-Site Bioremediation – The Sixth International Sym posium. San Diego. June 4 - 7.16. Johnson, P.C. and R.A. Ettinger. 2000. Pr ogress Towards Gaining a Better Understanding of Subsurface Vapor Migration. RCRA: Visions for the Future Conference. USEPA. August 15 –18. Washington, D.C..

17. Johnson, P.C. and R.A. Ettinger. 2000. An Empi rical Analysis of Data From the Colorado DoT Materials Laboratory Testing Site, Denver CO. RCRA: Visions for the Future Conference. USEPA. August 15 –18. Washington, D.C..

18. Kemblowski, M.W. and P.C. Johnson. 2000. Environmental Monitoring, Modeling, and Management and Bayesian Belief Networks. Envirosoft. June. Bilbao, Spain.

19. Arulantham, R., P. C. Johnson, and M. W. Kemblowski. 2000. Identifying Low-Risk MTBEImpacted Sites. Pacific Focus Ground Water Confer ence. February 17 – 18. San Francisco, CA.

20. Salanitro, J.P., P.C. Johnson, G.E. Spinnler, C.C. Neaville, P.M. Maner, S.M. Stearns, C.L. Bruce.
1999. Demonstration of the Enhanced MTBE Biorem ediation (EMB) IN Situ Process. In Situ and On Site Bioremediation – Fifth International Sy mposium. April 19-22, 1999. San Diego, CA.

21. Bruce, C.L., I.L. Amerson, P.C. Johnson, R.L. Johnson. 1999. Diagnostic Tools for Quantifying Oxygen Mass Transfer Rates. In Situ and On Site Bioremediation – Fifth International Symposium. April 19-22, 1999. San Diego, CA.

22. Bruce, C.L., P.C. Johnson, and R.L. Johnson 1998 . Methyl Tert-Butyl Ether Removal by In Situ Air Sparging in Physical Model Studies. The First International Conference on Remediation of Chlorinated and Recalcitrant Compounds. May 18-21. Monterey, CA.

23. Johnson, P.C., A. Das, R.L. Johnson, C. Bruce, A. Leeson, D. McWhorter, and R.E. Hinchee. 1997. Removal of Immiscible-Phase Hydrocarbons - E ffects of Process Control Changes, Chemical Properties, and Distribution. In Situ and On-Site Bioremediation: The Fourth International Symposium. April 28 - May 1, 1997. New Orleans.

24. Johnson, R.L., P.C. Johnson, A. Leeson, C.M. Voge l. 1997. Air Distribution During In Situ Air Sparging: Tracer and Geophysical Measurements. In Situ and On-Site Bioremediation: The Fourth International Symposium. April 28 - May 1, 1997. New Orleans.

25. Rutherford, K.W., D. Bass, W. McPhee, and P.C. Johnson. 1997. Estim ation of Oxygen Mass Transfer Coefficients During In Situ Air Sparging. In Situ and On-Site Bioremediation: The Fourth International Symposium. April 28 - May 1, 1997. New Orleans.

26. Johnson, R.L., P.C. Johnson, A. Leeson, C.M. Voge l. 1997. Air Distribution During In Situ Air Sparging: Tracer and Geophysical Measurements. The Fourth International Symposium - In Situ and On-Site Bioremediation. April 28 - May 1, 1997. New Orleans, LA.

27. Johnson, P.C.., A. Das, R.L. Johnson, A. Leeson, D. McWhorter, R. Hinchee, and C.M. Vogel. 1997. Effects of IAS Process Changes on the Removal of Immiscible-Phase Hydrocarbons. The Fourth International Symposium - In Situ and On -Site Bioremediation. April 28 - May 1, 1997. New Orleans, LA.28. Rutherford, K.W., D. Bass, W. McPhee, and P. C. Johnson. 1997. Estimating Oxygen Mass Transfer Coefficients During Air Sparging. The Fo urth International Symposium - In Situ and OnSite Bioremediation. April 28 - May 1, 1997. New Orleans, LA.

29. Westerhoff, P., L. Baker, P. Fox, P. Johnson, a nd S. Houston. 1997. A Low-Cost Strategy to Treating and Reuse Wastewater in Nogales, AZ. AWRA Long Beach ‘97. October 19-23.

30. Johnson, P.C., K. Balshaw-Biddle, T. Reeves, and C. Bruce. 1997. In Situ Air Sparging Studies Using the AATDF ECRS Large-Scale Physical Mode l. AATDF Conference. Rice University. February.

31. Johnson, P.C., R.L. Johnson, C. Neaville, and E.E. Hansen. 1995. Short-Term Pilot Tests - Reliable Indicators of Long-Term In Situ Air Sparging Performance? In Situ and On-Site Bioreclamation Conference - 3rd International Symposium. San Diego. April 24-27.

32. Johnson, R. L., N. R. Thomson, and P. C. Johnson. 1995. Does Sustained Groundwater Circulation Occur During In Situ Air Sparging. In Situ and On-Site Bioreclamation Conference - 3rd International Symposium. San Diego. April 24-27.

33. Rutherford, K. and P.C. Johnson. 1995. Interf acial Mass Transfer During In Situ Air Sparging - Effects of Process Changes and Lithology. AP I/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November.

34. Johnson, P.C., R.L. Johnson, C. Neaville, and E.E. Hansen. 1995. Short-Term Pilot Tests - Reliable Indicators of Long-Term In Situ Air Sparging Performance? AWPCA Annua l Conference - Quentin Mees Award. Phoenix. May.

35. Wheeless, W., S. Hicken, C. Beitler, J. Rowe, M.A. Robbins, R.E. Hinchee, P.C. Johnson, R.L. Johnson, and D.B. McWhorter. 1995. In Situ Air Sparging - Technology Demonstration for Remediating Groundwater Contaminated with Disso lved-Phase Constituents at Hill Air Force Base. API/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November.

36. Johnson, P.C., Rounds, D., and C.C. Stanley. 1994. Risk-Based Corrective Action (RBCA) at Petroleum Release Sites. API/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November.

37. Neaville, C., P.C. Johnson, and R.L. Johnson. 199 4. Evaluation of Air Sparging Technology at a Gasoline UST Site. AEHS Petroleum Contaminated Soils Conference. Long Beach, CA.

38. Sabadell, G.P., J.B. Gustafson, P.C. Johnson, E.R. Cruz, L.W.R. Dicks and C.C. Wang. 1993. Evaluation of Soil Vapor Extraction System Design and Operation Utilizing Tracer Tests. Presented at the CSCE-ASCE National Conference on Environmental Engineering. July.

39. Johnson, P.C. and C.C. Stanley. 1993. An Integrated Exposure/Risk-Based Corrective Action Approach for Underground Storage Tank Sites. Presented at the 86th Annual Meeting and Exhibition of the Air & Waste Manageme nt Association. Denver, Colorado.40. Stanley, C.C., P.C. Johnson, R.K. Wenzlau, J.L. R ous, J.F. Vargas, and J.L. Peterson. 1992. An Exposure/Risk-Based Corrective Action Approach for UST Sites. Proceedings of Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX. November.

41. Johnson, P.C., M.W. Kemblowski, and J.D. Colthart. 1988. Practical Screening Models for Soil Venting Applications. Proceedings; Petroleum Hydrocarbons and Organic Chemicals in Ground Water Conference, National Water Well Association, American Petroleum Institute; Houston, TX.

Sponsored Research - External Grants and Gifts:

1. Johnson P.C. and P. Dahlen. Improving Our Unde rstanding of Dissolved Groundwater Plume Sources at Petroleum-Impacted Sites Through Physi cal Model, Mathematical Model, and Field-Site Studies. Chevron.$500,000. 9/1/2010 – 8/31/2012.

2. Johnson, P.C. and P. Dahlen. Integrated Field-Scale, Lab-Scale, and Modeling Studies for Improving Our Ability to Assess the Groundwater to Indoor Air Pathway at Chlorinated Solvent Impacted Sites. SERDP. $1,256,000. 10/1/2009 – 9/30/2012.

3. Johnson, P. C. and P. Dahlen. Chemical Oxidation Technologies. Johnson. Shell Global Solutions. $120,000. 12/1/08 – 6/31/11.

4. Johnson, B. Rittmann. Assessment of the Natural Attenuation of NAPL Source Zones and PostTreatment NAPL Source Zone Residuals. ESTCP. $899,424. 4/1/07 – 3/30/10.

5. Johnson, P.C. Capillary Properties of Soils and Residual Fluid Levels. American Petroleum Institute. $50,000. 1/1/2010 – 12/31/2010.

6. Johnson. Field Study of Vapor Intrusion of Petr oleum Hydrocarbon Vapors. Chevron. $40,000.

1/1/08 – 1/1/09

7. Johnson. Vapor Migration Studies. Chevron. $80,000. 1/1/06 – 12/31/07.

8. Johnson. Oxygen Delivery Technologies. She ll Global Solutions. $20,000. 1/1/07 – 12/31/07.

9. Johnson. Critical Evaluation of State-of-the-A rt In Situ Thermal Treatment Technologies for
DNAPL Source Zone Treatment. Battelle (from ESTCP). $325,000. 2/1/05 – 9/31/07.

10. Johnson. Computer Simulation Of Subsurface Hydr ocarbon Vapor Migration In The Vicinity Of Homes And Buildings. Arco/Atlantic Richfield. $30,000. 9/1/05 – 8/31/06.

11. Razdan, Johnson. East Valley Water Forum Simu lations. East Valley Water Forum. $117,500.

9/1/05 – 9/1/06.

12. Johnson. Bench-Scale Evaluation Of Long-Term Bi osparging Effect On Ground Water Quality In Diluent Source Areas At The Guadalupe Restoration Project. Unocal. $57,860. 6/14/04 – 6/1/06.13. Johnson. Field Evaluation of Oxygen Delivery Technologies. Shell Global Solutions. $50,000.

1/1/05 – 5/31/06.

14. Johnson. Modeling of Vapor Intrusion of Petrol eum Hydrocarbon Vapors. Chevron. $30,000.

1/1/05 – 12/31/06.

15. Johnson. Numerical Modeling of Vapor Intrus ion of Petroleum Hydrocarbon Vapors. British Petroleum. $20,000. 1/1/04 – 1/31/05.

16. Johnson. Mobil Foundation Gift. $10,000. 1/1/04 – 1/31/04.

17. Johnson. Innovative Technologies for Assessing and Treating Impacted Aquifers. U.S. Navy. $275,000. 10/1/02 – 9/30/04.

18. Anderson-Rowland and Johnson. Collaborativ e Interdisciplinary Research Community /Maricopa Engineering Transition Scholars (CIRC/METS). National Science Foundation. $400,000. 7/1/03 – 6/30/07.

19. Johnson. Predicting Groundwater Quality Downgrad ient of Permeable Reaction Barriers. U.S. Navy. $200,000. 10/1/03 – 5/30/06.

20. Johnson. Release of Regulated Substances to Arizona Ground Water – Supplemental Data Collection. Arizona Department of Environmen tal Quality. 7/1/2002 – 12/31/2002. $150,000.

XCT9312.

21. Johnson. Release of Regulated Substances to Ar izona Ground Water. Arizona Department of Environmental Quality. 2/1/2001 – 12/31/2002. $331,143. XCT9312.

22. Johnson. Remediation of MTBE -Impacted Aquifers. Gift – Shell Oil Foundation. $10,000.

1/1/02 – 12/31/02.

23. Johnson. Environmental Restoration and Ri sk Assessment. Mobil Research Foundation. $10,000. 1/1/02 – 12/31/02.

24. Johnson. Demonstration of the Enhanced MTBE Bioremediation Process at Port Hueneme, CA. Equilon Enterprises. $80,114. 9/15/99 – 12/31/02. ORCA00310.

25. Johnson. Innovative Technologies for Assessing and Treating MTBE-Impacted Aquifers – Phase 1, 2, and 3. US Navy. $374,198. 8/30/99 – 5/31/02. XCA6526.

26. Johnson. Assessing the Longevity of Hydrocarbon Sour ce Zones. Rio Tinto. $51,528. 9/1/99 –

12/31/01.

27. Johnson. NEX MTBE Plume Characterization. US Navy. $5,000. 6/8/99 – 6/1/00. XCA6525.

28. Johnson. Gift – Remediation of MTBE-Impacted Aquifers. Equilon Enterprises. $20,000.

12/1/99 – 12/1/0029. Johnson. Gift – Remediation of MTBE-Impacted Aquifers. Equilon Enterprises. $10,000.

10/19/99 – 10/18/00.

30. Baker and Johnson. Management of Nitrate C ontaminated Aquifers. Salt River Project. $22,306. 6/1/99 – 5/16/01. XCT9292.

31. Johnson. Gift - Environmental Restoration and Risk Assessment. Mobil Research Foundation. $12,000. 12/1/98 – 12/1/99.

32. Johnson. Gift - Remediation of MTBE in Ground Water. Equilon Enterprises. $86,000. 6/29/98 –

6/1/02.

33. Westerhoff and P.C. Johnson (40%). A Zero-Valent Treatment Process for Removing Nitrate and
Perchlorate from Groundwater. American Wa ter Works Association. $64,812. XCT9283.

34. Johnson and R. Johnson (Oregon Gr aduate Institute). Vadose Zone Natural Attenuation. American Petroleum Institute. $95,058. XCT9272. 2/12/97 - 6/1/99.

35. Johnson (Oregon Graduate Institute) and P. Johnson (10%). Natutal Attenuation of Dissolved
MTBE Plume. American Petroleum Institute . $90,000. 970060. 2/12/97 - 6/1/99.

36. Johnson (33%), R. Johnson (Ore gon Graduate Institute), and M. Kemblowski (Utah State University). Diagnostic Tools for the Monitori ng and Optimization of In Situ Air Sparging Systems. American Petroleum Institute. $133,117. XCT9255. 1/1/96 - 12/31/99.

37. Johnson and M. Kemblowski (Utah State Univer sity). Vadose Zone Natural Attenuation. American Petroleum Institute. $45,864. 970060. 2/12/97 - 12/31/97.

38. Johnson. In Situ Bioremediation of Contam inated Aquifer Soils. Battelle/SERDP/USAF. $223,152. XCJ 6230. 11/1/96 - 12/31/98.

39. Johnson. Chlorinated Hydrocarbon Remediation. Sa lt River Project. $22,000. 5/1/95 - 11/1/97.

GFT4628.

40. Johnson. Gift - Environmental Restoration and Risk Assessment. Mobil Research Foundation. $20,000. 2/1/97 -. XC51001.

41. Johnson and R. Charbeneau (U. Texas). Graphical Tools for Determining Site-Specific RiskBased Soil Screening Levels for the Soil to Groundwater Transport Pathway - A Practical
Alternative to Generic Dilution Attenuation Factor s. American Petroleum Institute. $105,000.

2/1/95 - 7/31/96. XCT 8786.

42. Johnson. Iron-Induced Hydrocarbon Degradation. Arizona Department of Water Resources. $24,470. 95-0483. 11/1/95-2/1/97.

43. Johnson. Regional Water Quality and Suppl y Management Strategies for the Phoenix Metropolitan Area. Arizona Department of Wa ter Resources. $24,220. XCT1465. 11/1/95-

2/1/97.44. Fox, S. Houston, W. Houston, P.C. Johnson (25%). Direct Well Recharge of Tertiary Effluent. Arizona Department of Water Resources. $77,558. XCT9251. 11/1/95 - 2/28/97.

45. Westerhoff, L. Baker, P. Johnson (20%). Linki ng Nitrate Models to Existing Salt River Project Canal Hydraulic Models to Pred ict Water Quality Impacts of Well Pumping. Salt River Project. $25,358. GFT 4653. 6/1/96 - 5/31/97.

46. Johnson. An Evaluation of EPA-Recommended Stack Emissions Monitoring Using Tracer Gas Mass Balance Approach. Salt River Project. $14,327. GFT 4654. 6/1/96 - 5/31/97.

47. Johnson. Evaluation of the Use of Elemental Ir on to Treat DBCP-Impacted Groundwater. Salt River Project. $9,327. GFT 4654. 6/1/96 - 5/31/97.

48. Baker, P. Westerhoff, P. Fox, S. Houston, P. Johnson (15%), C. Klopotek. US-Mexico Border Water Resource Management Technologies for Sust ained Development - Low Cost Strategy for Treating and Reusing Wastewater. SCERP/ USEPA. $135,000. 96287. 9/1/96 - 8/31/97.

49. Johnson. Environmental Restoration and Risk Assessment. Mobil Research Foundation. $20,000.

10/1/94 -. XC51001.

Sponsored Research - Equipment Loans:

1. Experimental Controlled Release System.DOE/ DOD/ AAATDF/ Rice University. 1/1/97 - 12/31/98.
970936.

2. Geoprobe Unit. University of California at Santa Barbara. 6/1/98 – 11/1/05

Sponsored Research - Internal Grants:

1. Johnson, P. Westerhoff, S. Beaudoin. Assessing the Impact of New Products and Process Changes on Environmental Resources. $22,000. CEAS. 7/29/97 - 7/29/98.

2. Johnson. Chemistry Module for U ndergraduate Civil Engineers. FEIGIA. $6000. 6/1/95 - 5/31/96.

ST1001.

3. Johnson. Restoration of Aquifers Contaminated w ith Solvents. FGIA. $6000. XCRG0110. 4/1/95 -

3/31/96.

4. Johnson. Bioremediation of Contaminated Aquifer Soils. $8000. OVPR. 9/1/94 - 8/31/95.

XCR230.

S TUDENT T HESES AND D ISSERTATIONS S UPERVISED

Masters Degrees Awarded:

Student Date M.S. Thesis TitleLisa Clifton 12/08 Effect of Dissolved Oxygen Manipulation on the Benzene Flux from a Low Permeability Soil Layer

Pamela Maass 12/05 Modeling Groundwater Quality Changes Down-gradient
of Permeable Reactive Barriers

Roberta Lenski 12/04 Source Longevity Estimates for Ground Water Impacts
at the Former Williams AFB Site

Maikel Mendez 5/03 Use of MFI Tests to Project Secondary Effluent Recharge Well Performance in Costa Rica

Makiko Matsumuro 12/02 Occurrence of Fuel Oxygenates in Groundwater at Arizona Leaking Underground Fuel Sites

Suzanne Braunschneider 12/00 Visu alization Studies for Bioaugmentation Jennifer Sigley [w/ S. Beaudoin – ChE] 12/99 Use of Nonionic Surfactants for Reducing Sulfuric Acid Mist Emissions During the Copper Electrowinning

Process

JeskoSollner 6/99 Bioremediation of a MTBE-Contaminated Site – Factors Influencing the Transport of Bacteria Through Soil and Aquifer Sand [Technical University Berlin]

Victoria Hermes 12/98 Numerical Modeling of Vadose Zone Natural
Attenuation Sophie Roggemans 12/98 An Empirical Asse ssment of Natural Attenuation in the
Vadose Zone Patricia McSparren 12/98 Regional Scale Groundwater Flow Modeling and Assessment of the Impacts of Treated Effluent Discharge near the US-Mexico Border at Nogales Illa Lyn Amerson 12/97 Diagnostic Tool s for the Monitoring and Optimization of In Situ Air Sparging Systems Angie Luckie 5/97 Long-Term Pump Test Performance of a Deep Horizontal Well in a Highly Heterogeneous Formation

Amar Das 12/96 Laboratory-Scale Study of Volatilization from Residual Source Zones During Air Sparging

David Abranovic 5/96 Graphical Tools for Determining Site-Specific RiskBased Soil Screening Levels Kyle Wayne Rutherford 12/95 Effects of Process Control Changes on Interfacial Mass Transfer Rates During In Situ Air Sparging Jennifer Campbell 12/96 Iron-Induced Degr adation of Chlorinated Solvents in Groundwater [MSE Project] Cindy Barker 5/96 Learning Tools for Undergraduate Students - Chemistry Module for Civil Engineers [MSE Project]

Doctoral Degrees Awarded :

Student Date Ph.D. Project Title Hong Luo 5/09 Field and Modeling studies of Soil Vapor Migration into Buildings at Petroleum Hydrocarbon Impacted Sites Jennifer Triplett-Kingston 5/08 Critical Ev aluation of Thermal-Based Remediation Technologies

Luis Lesser 5/08 Spatial and Tempor al Variations in MTBE DegradingActivity

LilianDeize de Abreu 3/05 A Three-Dimensional Numerical Model for Subsurface Vapor Migration to Enclosed Spaces Zhuang Liu 12/04 Accelerated Bench-Scale Weathering Tests for Petroleum Hydrocarbons

Paul Dahlen 12/04 Impact of Le aking Underground Storage Tanks on
Arizona Groundwater Resources Ying Xu 4/02 Empirical Analysis of Historical Trends and Prediction
of Future behavior of Nitrate Concentrations in Groundwater in the SRP Service Area, AZ

Cristin Bruce. 6/01 Performance Expectations for In Situ Air Sparging Systems

S TUDENT T HESES AND D ISSERTATIONS S UPERVISED

Current Graduate Projects in Progress:

Student Degree Project Ryan Ekre Ph.D. Source Zone Natural Attenuation of DNAPL Sources Elsy Escobar Ph.D. Vapor Co-Migration of Aerobically Biodegradable Components Bridgette Cavanagh Ph.D. Assessing the Impact of Chemical Oxidation for Treatment of Petroleum-Impacted Sites

Chase Holton Ph.D. Vapor Migration of Chlorinated Solvents from
Groundwater to Indoor Air

Post-Doctoral Students:

Paul Dahlen (2004 – 2007) Hong Luo (2009 – present) Eric Henry (2001) – currently at University of North Carolina , Wilmington Cristin Bruce (2001 – 2003) – currently at Shell Global Solutions, Houston, TX.

Undergraduate Projects Supervised:



### 1. Shawn Whitmer - Iron-Induced Chlori nated Hydrocarbon De gradation Studies 2. Makiko Matsumuro – WISE Progr am. Vapor Transport Studies.

P ROFESSIONAL AND S CIENTIFIC S ERVICE

Local Professional Committees and Appointments:

1. Governor Appointment to the Arizona U ST Technical Appeals Board (1998 - 2002)

2. Governor Appointment to the Arizona Water Quality Assurance Revolving Fund (WQARF) Advisory Panel (1997 - 2000)3. ADEQ Ground Water Study Working Gr oup (1999 - 2000)

4. Arizona Groundwater Clean-up Standards Task Force (1996 - 1997)

5. Arizona Department of Environmental Quality Director’s Advisory Panel on Soil Clean-up Standards (1996)

Scientific and Professional Society Memberships:

1. American Society for Testing and Materials - Co-Chairman, Risk-Based Corrective Action for Superfund and Self-Directed Cleanups Task Group (1995 - 1997)

2. Groundwater Remediation Technologies Analysis Center - Guidance Committee Member (1995 - 1998).

3. Advanced Applied Technology Demonstration Facility (DoD - AATDF) Program - Advisory Committee Member (1994 - 1998)

4. National Ground Water Association

5. American Chemical Society

6. American Society of Civil Engineers

Conference Activities:

1. Session Chairman, Annual SERDP/ESTCP Partners in Innovation Conference. Vapor Intrusion. Washington, D.C.. (2010).

2. Session Chairman, International Conference on Ch lorinated Solvents and Other Recalcitrant Compounds. Combining Thermal with Other Remediation Technologies. Monterey, CA (2010).

3. Session Chairman, Annual SERDP/ESTCP Partners in Innovation Conference. Vapor Intrusion.Washington, D.C.. (2009).

4. Session Chairman, International Conference on Ch lorinated Solvents and Other Recalcitrant Compounds. Combining Thermal with Other Remediation Technologies. Monterey, CA (2008).

5. Session Chairman, Third International Conference on Chlorinated Solvents and Other Recalcitrant Compounds. Monterey, CA (2002).

6. Session Chairman, In Situ and On-Site Bioreclamation Conference - 6th International Symposium. June 4- 7. San Diego, CA (2001).7. Session Chairman, Second International Conf erence on Chlorinated Solvents and Other Recalcitrant Compounds. Monterey, CA (2000).

8. Session Chairman, In Situ and On-Site Bioreclamation Conference - 5th International Symposium. San Diego, CA (1999).

9. Session Chairman, First International Conference on Chlorinated Solvents and Other Recalcitrant Compounds. Monterey, CA (1998).

10. Session Chairman, In Situ and On-Site Bioreclamation Conference - 4th International Symposium. New Orleans, LA (1997).

11. Session Chairman, Advanced Applied Technology De monstration Conference. Rice University. Houston, TX (1996).

12. Session Chairman, In Situ and On-Site Bioreclamation Conference - 3rd International Symposium. San Diego, CA (1995).

13. Session Chairman, API/NGWA Conference: Petroleum Hydrocarbons and Organic Chemicals in Groundwater. Houston, TX (1993).

Journal Editor Service:

1. Ground Water Monitoring and Remediation – Editor-in-Chief (2003 - )

2. Journal of Bioremediation (1996 - 2003) - Associate Editor

3. International Journal of Soil Contaminati on (1996 - 2003) - Editorial Advisory Board

Journal Referee Service:

1. Bioremediation Journal (Associate Editor)

2. Ground Water

3. Ground Water Monitoring and Remediation

4. Environmental Science and Technology

5. Environmental Engineering Science

6. Water Resources Research

7. Separation Science and Technology

8. ASCE Journal of Environmental Engineering9. Soils (Associate Editor)

10. Water Environment Research

11. Biotechnology and Bioengineering

12. International Journal of Bioremediation

Proposal Reviewer:

1. National Science Foundation - Directorate for Geosciences (1993)

2. USEPA OUST Program (1994 - 1995)

3. Department of Energy/Department of Defense - AATDF Program (1993 - 1997)

4. DOE SERDP Program (1995, 1999, 2003, 2004, 2005)

Other:

Mentor - USEPA EarthVision Program (high school students; 1996 - 1997)

U NIVERSITY C OMMITTEE S ERVICE AND O THER S ERVICE

University-Level Service

Associate Vice President – Research (2004 – 2006)

College of Engineering and Applied Scien ces/Ira A. Fulton School of Engineering:

Ira A. Fulton School of Engineering: Dean (2011 – )

Ira A. Fulton School of Engineering: Executive Dean (2006 –2010)

College of Engineering and Applied Science Associate Dean – Research (2003 - 2004)

College of Engineering and Applied Science Inte rim Associate Dean – Research (2002 - 2003)

Dean’s Personnel Advisory Committee – Chair (2000 – 2001, 2001 – 2002)

Dean’s Personnel Advisory Committee (1999 - 2000)

College of Engineering and Applied Sc ience Research Committee (1998 – 1999)

College of Engineering and Applied Science ECE-100 Curriculum Committee (2000 – 2001, 2001 – 2002)Department of Civil and Environmental Engineering:

Associate Chair – Graduate Programs (2000 – 2001, 2001 – 2002)

ASCE Student Chapter Advisor (2001 – 2002)

CEE Personnel Committee - Chair (1997 – 1998, 1998 - 1999)

CEE Advisory Committee (1999 – 2000, 2001 – 2002)

CEE Self-Study Committee (2001 – 2002)

CEE Faculty Search Committee – Chair (1996 – 1997)

CEE Faculty Search Committee (1995 – 1996)

CEE Scholarship Committee (2001 – 2003)

E VALUATION OF I NSTRUCTION

– A WARDS

ASU College of Engineering Teaching Excellence Award 2002*

ASU Parents Association Teacher of the Year Finalist 2000

ASU College of Engineering Teaching Excellence Award 1998*

ASCE Student Chapter Best Teacher Award 1996

* - The College of Engineering and Applied Sciences (CEAS) presents this award only to two faculty each

year.E VALUATION OF I NSTRUCTION

– S UMMARY OF S TUDENT E VALUATIONS 

### [max. score = 5.0]

Year and

Term Course # Course
Title No.
Students Instructor
Evaluation Course
Evaluation

2011 CEE564 Contaminant
Fate and Transport 22 4.73 4.16

2010 ASU101 Introduction to
ASU 18 4.94 4.57

2010 CEE560 Soil and
Groundwater
Remediation 23 4.44 4.12

2009 CEE564 Contaminant
Fate and Transport 25 4.85 4.43

2009 CEE560 Soil and
Groundwater
Remediation 9 4.92 4.49

2009 ASU101 Introduction to
ASU 19 NA NA

2008 CEE564 Contaminant
Fate and Transport 16 4.55 4.39

2007 CEE560 Soil and
Groundwater
Remediation 13 4.59 4.39

2007 ASU101 Introduction to
ASU 14 NA NA

2007 CEE598 Special Topics: Data Systems –
Environmental 7 4.85 4.74

2006 CEE591 Seminar 25 NA NA

2006 CEE564 Contaminant
Fate and Transport 24 4.61 4.25

2006 CEE 598 Special Topics:
Advanced
Environmental Chemistry 9 4.40 4.41

2005 CEE 598 Special Topics: Data Systems –
Environmental 10 4.86 4.71

2005 CEE 564 Contaminant
Fate and Transport 29 4.55 4.04

2003 CEE 564 Contaminant
Fate and 23 4.38 3.98Transport
2002 CEE 560 Soil and
Groundwater
Remediation 25 4.77 4.40

2002 Spring CEE 598 Contaminant
Fate and Transport 18 4.79 4.43

2001 Fall CEE 540 Groundwater Hydrology (new course) 23 4.73 4.42

### E VALUATION OF 

### I NSTRUCTION



### – S UMMARY OF 

### S TUDENT 

### E VALUATIONS 

### [ CONT 

### .] [max. score = 5.0]

Year and

Term Course # Course
Title No.
Students Instructor
Evaluation Course
Evaluation 2001 Spring CEE 598 Contaminant
Fate and Transport 18 4.84 4.45

2000 Fall CEE 540 Groundwater Hydrology (new course) 23 4.73 4.42

1999 Fall ECE 100 M Introduction to Engineering: Modeling 45 4.47* 3.71

1999 Fall CEE 598 Contaminant
Fate and Transport 11 4.88 4.49

1998 Fall ECE 100 M Introduction to Engineering: Modeling 32 4.68** 3.46

1998 Fall CEE 560 Soil and
Groundwater
Remediation 12 4.79 4.32

1998 Spring CEE 598 Contaminant
Fate and Transport 21 4.63 4.31

1998 Fall CEE 560 Soil and
Groundwater
Remediation 12 4.79 4.32

1998 Spring CEE 598 Contaminant
Fate and Transport 21 4.63 4.31

1997 Fall CEE 560 Soil and
Groundwater
Remediation 20 4.65 4.27

1997 Fall ECE 300 Intermediate Engineering Design 39 4.50*** 4.30

1996 Fall CEE 361 Introduction to
Environmental Engineering 26 4.81 4.18

* - highest rating of ECE100 M instructors that semester - and highest rating achieved by any ECE100 modeling instructors in the three-year period ** - highest rating of ECE100 M instructors that semester *** - highest rating of ECE300 instructors that semester For reference, the average ECE100 M instructor rating is approx. 3.9 

### For reference, the average ECE300 instructor rating is approx. 3.8E VALUATION OF I NSTRUCTION

– N EW C OURSES D EVELOPED CEE560 – Soil and Ground Water Remediation CEE598 – Contaminant Fate and Transport ECE100 – Curriculum Development Committee (ECE100 revisions) CEE598 – Environmental Data Systems and Analysis

W ORKSHOPS /S HORT C OURSES D EVELOPED

USEPA Vapor Intrusion Workshop P. C. Johnson, T. McAlary, I. Hers, H. Da wson, R. Truesdale, H. Schuver and others
• March and October 2004 , March 2005, March 2006

Vapor Intrusion Workshop P. C. Johnson, R.A. Ettinger, T. McAlary, E. Nichols, and others • September and October 2003

In Situ Air SpargingDoD Field Camp Course P. C. Johnson, R.L Johnson, C. Bruce, P. Dahlen, J. Osgood • May 2002, July 2002 (twice)

MTBE Remediation [requested by USEPA and CA State Water Quality Control Board] • April 1999, May 1999, June 1999, September 1999

Risk Assessment J. Rocco, L. Hay-Wilson, J. Mercer, J. Till, Johnson, P.C. Santa Fe, NM. • April 1998, April 1999.

USEPA/ASTM ES-38 Risk-Based Corrective Action Workshop ASTM ES-38 Task Group • August 1996, March 1996, October 1995, September 1995, May 1995, December 1994

Air Sparging Workshop International Network for Environmental Training P.C. Johnson, R.E. Hinchee
• December 1994

Risk-Based Corrective Action Workshop P.C. Johnson, C.C. Stanley, G.E. DeVaull, R.A. Ettinger, P.M. McAllister • AWMA Conference March 1994, AEHS Conference March 1994

Aeration-Based Technologies (Soil Venting, Air Sparging, Bioventing) - Environmental Education Enterprises P.C. Johnson, R.E. Brown and G.E. Hoag • October 1995, January 1995, June 1994, March 1994, June 1993, December 1993

Groundwater Contamination from Petroleum HydrocarbonsUniversity of Texas - College of Engineering, Austin, TX. Charbeneau, R., P. Bedient, C.Y. Chiang, D.Daniel, P.C. Johnson, R. Loehr, G.E. Speitel Jr., and J.

Weaver. • April 1994, April 1993, October 1992, April 1992, April 1991

USEPA Strategic Technology Evaluation Workshop
P.C. Johnson and D. Mohr • February 1994

Soil Remediation Workshop - Petroleum Contaminated Soils Conferences Johnson, P.C. J.P. Salanitro, L.W.R. Dicks, M.H. Huesemann, G.M. Deeley, A.R. Marsden, Jr., W.G. Rixey, and J.B. Gustafson. • March 1993, September 1992, March 1992, September 1991, March 1991

USEPA Corrective Action Technology Transfer Workshop on NAPL Recovery and Residual Hydrocarbon Removal. Johnson, P.C., J. Parker, T. Peargin • January 1993

An Exposure/Risk-Based Corr ective Action for UST Sites - Petroleum Contaminated Soils Conferences Johnson P.C. and C.C. Stanley
• March 1993

HyperVentilate© - A Software Guidance Sy stem for Vapor Extraction - Applications

. P.C. Johnson • USEPA Region VII - March 1994, U SEPA Region VII - February 1994



### Other Professional Information

Past or Current Consultant to: US Environmental Protection Agency IT Corporation US Department of Defense Battelle US Department of Energy Envirogen Rice University Siemens Parsons-Engineering Science Phillip Environmental
Baker Environmental BP Oil Mobil Oil Corporation GeoMatrix
Lockheed Chevron
Occidental Chemical State Regulatory Agencies
Motorola Lawrence Live rmore National Laboratory
Unocal Oxygenated Fuels Association Allied Signal/Honeywell Woodward-Clyde Consultants Equilon Enterprises California Water Quality Control Board Groundwater Services, Inc. Geosyntec Shell Global Solutions Haley and Aldrich**Peer Reviewer**  **Conflict of**  **Interest Certification** 

**Peer Review:**  **Proposed Rule:**  **Addition of**  **a Subsurface**  **Intrusion Component**  **to the**  **Hazard Ranking**  **System; 40**  **CFR Part**  **300; EPA-HQ-SFUND-2010-1086;**  **FRL_XXXX-X (review**  **draft).**

**A conflict**  **of interest**  **or lack**  **of impartiality**  **exists when**  **the proposed**  **peer reviewer**  **personally (**  **or the**  **peer reviewer's**  **immediate family),**  **or his**  **or her**  **employer, has**  **f nancial** 

**i interests**  **that may**  **be affected**  **by the**  **results of**  **the**

**peer review;**  **or may**  **provide an**  **unfair competitive**  **advantage to**  **the peer**  **reviewer (or**  **employer); or**  **if the**  **peer reviewer's**  **objectivity in**  **performing the**  **peer review**  **may be**  **impaired due**  **to other factors.**  **When the**  **Peer Reviewer**  **knows that**  **a reasonable**  **person with**  **knowledge of**  **the facts**  **may question**  **the peer**  **reviewer's impartiality**  **or financial**  **involvement, an**  **apparent lack**  **of impartiality**  **or conflict**  **of interest**  **exists.**

**The following**  **questions, if**  **answered affirmatively,**  **represent potential**  **or apparent**  **lack of**  **impartiality (any**  **affirmative answers**  **should be**  **explained on**  **the back**  **of this**  **form or**  **in an**  **attachment):**



# • **Did you**  **contribute to**  **the development**  **of the**  **document under**  **peer review,**  **or were**  **you consulted**  **during its**  **development, or**  **did you**  **offer comments**  **or suggestions**  **to any**  **drafts or**  **versions of**  **the document**  **during its**  **development? 0"No**  **O Yes** 



# • **Do you**  **know of**  **any reason**  **that you**  **might be**  **unable to**  **provide impartial advice**  **on the**  **matter under** 

**con Ji<l**  **eration in**  **this peer**  **review, or**  **any reason**  **that your**  **impartiality in**  **the matter**  **might be**  **questioned? GtNo**  **O Yes** 

**.**



# • **/ Have**  **you had**  **any previous**  **invo l**  **v eme**  **nt with**  **the review**  **document(s) under**  **consideration? E'.'l"No**  **D Yes** 



# • **Have you**  **served on**  **previous advisory**  **panels, committees,**  **or subcommittees**  **that have**  **addressed the**  **topic**
**under consideration?**  **� o O**  **Yes**

**• Have**  **you made**  **any public**  **statements (written**  **or oral)**  **on the**  **issue? i:1"Noo**  **Yes**



# • **H.avc you**  **made any**  **public statements**  **that would**  **indicate to**  **an observer**  **that you**  **have taken**  **a position on** 

**the issue**  **under consideration?**  **�o o**  **Yes**



# • **Do you,**  **your family,**  **or your**  **employer have**  **any financial**  **interest(s) in**  **the matter**  **or topic**  **under peer**  **review,**

**or could**  **someone with access**  **to relevant**  **facts reasonably**  **conclude that**  **you (**  **or your**  **family or**  **employer)**
**stand to**  **benefit from**  **a particular**  **outcome of**  **this peer**  **review? t&o**  **o Yes** 

**With r**  **egard to**  **real or**  **apparent conflicts**  **of interest**  **or questio**  **ns of**  **impartiality, the**  **following provisions**  **shall apply**  **for the**  **duration of**  **this peer**  **review:**

**(a) Peer**  **Reviewer warrants,**  **to the**  **best of**  **his/her knowledge**  **and beliet:**  **that there**  **are no**  **relevant facts**  **or circumstances**  **that could**  **give rise**  **to a**  **n actual,**  **apparent, or**  **potential organizational**  **or personal**  **conflict of**  **interest,**

**or that**  **Peer Reviewer**  **has disclosed**  **all such**  **relevant information**  **to EMS**  **or to**  **EPA. (b)**  **Peer Reviewer**  **agrees that**  **if an**  **actual, apparent,**  **or potential**  **personal or**  **organizational conflict**  **of interest**  **is identified**  **during perfonnance**  **of this**  **peer review,**  **he/she immediately will**  **make a**  **full disclosure**  **in writing**  **to EMS.**  **This disclosure**  **shall include**  **a description**  **of actions**  **that Peer**  **Rcvie\ver (**  **or his/her**  **employer) has**  **taken or**  **proposes**
**to take**  **after consultation**  **with EMS**  **to avoid,**  **mitigate. or**  **neutralize the**  **actual, apparent,**  **or potential**  **organizational conflict**  **of interest.**  **Peer Reviewer**  **shall continue**  **performance until**  **notified by**  **EMS of**  **any contrary**  **action to**  **be** 

# �- **'--.-Q_ l-;g,12.** 

**c Check**  **here if**  **any explanation**  **is attached**  **Signature Date**  

# ? **U>'--\ (_**  

# So **�(1�**

**Printed Name**  

# &,30t>f4 **�Jak lhtcJ��:h** 

**Affiliation/Organization**

114 114

# Peer Reviews

Kimi Klein & Dot Lofstrom (Joint Reviewers, California DTSC)

• Charge Questions Comments

• CVs

• COI Certifications

### Peer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a s ubsurface intrusion (SsI) component to the Hazard Ranking System (HRS). S ubsurface intrusion is the migration of hazardous substances from the unsaturated zone and/or the surf icial ground water into overlying structures. The HRS is the principal mechanism the EPA uses to evaluate site s for placement on the National Priorities List (NPL). The subsurface intrusion component addition (this add ition) would primarily expand the number of available options for EPA and state and tribal organizations pe rforming work on behalf of EPA to evaluate potential threats to public health and the environment from releases of hazardous substances.

This addition will allow the HRS evaluation to directly consider human exposure to hazardous substances that enter building structures through subsurface intrus ion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relative potential risk. The Agency is not considering changes to the remainder of the HRS except for minor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System should include expertise in:

Panelist from non-specified sector: Panelist must have a strong working knowledge of policy and technical issues related to the topic of vapor intrusion. Knowledge of recent developments in vapor intrusion technologies and research is required, in addition to working knowledge of federal vapor intrusion response programs. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile hazardous substances is necessary. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

Peer Review Charge Questions

1. Potential for subsurface exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a rele ase of a hazardous substance when an actual release has occurred through either chemical analysis or direct observation. The current HRS also evaluates the potential for a release to occur within the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is determined by the consideration of pathway specific factors that aid the site evaluator in predicting whether a release to the pathway is likely to occur. These factors are based on containment features of the source of contamination (whether or not hazardous substance can get out), route characteristics specific to each pathway (how far hazardous substances could migrate based on knowledge of site conditions) and include physical/chemical properties of the hazardous substances being evaluated (how the hazardous substances act in the environment).

### Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure of

intruded hazardous substances for the subsurface intrusi on addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the Johnson-Ettinger m odel and also considered multiple lines of evidence approaches which estimate the levels of contaminant exposure based on numerous route characteristics. In addition, EPA examined the relationship between these factors to determine which have the greatest influence on the likelihood that an exposure would occur, and then incorporated these factors within its proposed approach. EPA also gave careful consideration to ensure that the data necessary to obtain route

characteristic factors could be measured or calculated on a site-specific basis and in a manner consistent with current HRS evaluations. Based on the Agency’s analysis, the following three factors for which sufficient site-specific information could be collected during a site inspection represented the greatest impact on the potential for exposure: (1) depth to contamination; (2) vertical migration; and (3) vapor migration potential (see Figure 1).

Figure 1

Charge Question #1 : Is EPA’s prop osed approach scientifically reasonable for evaluating and assigning proportional weightings for the following when evaluating potential for exposure? If no, what alternative approach would you recommend?

### a. Consideration of the construction/structure type for which sufficient site-specific information could be collected during a site inspection for the occupied structure;

b. Distance be tween occupied structure and depth of contamination; and c. Evaluation of the vertical migration factor based on the thickness and porosity /permeability of geologic materials in the interval between the lowest point of an occupied structure and the highest known point of hazardous substances in the subsurface.

1) There is no provision for significant volatile organic chemical (VOC) concentrations detected in

soil and/or surficial groundwater but without struct ures. Alternative: Provide default structure properties.

2) The vertical migration factor ranking consid ers certain geologic factors and identifies karst, lava tubes, open fractures (5.2.1.1.2.2) as features that would allow channelized flow. Manmade preferential pathways such as utility corridors and sewer lines should be included in the HRS assessment, if identified in the site inspection. Alternative: Expand the definition of channelized flow to include most commonly encountered features and/or include that expanded list in the regulatory language (Perhaps as part of Table 5-15 Vertical Migration Factor Values).

### 2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity factor reflects the risk consideration related to the magnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pathways. At each site evaluated, EPA uses a four-tiered hierarchy for calculating the hazardous waste quantity that is based on (1) constituen t quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original sources (how much has migrated and how much can be released in the future). In the soil exposure pathway, the hazardous waste quantity does not include the total amount of hazardous substances in all site sources, but rather is based on the amount of hazardous substances to which a receptor can be exposed where actual contamination has been documented. In other words, for the soil exposure pathway, the risk posed by a release of hazardous substances is directly related to the amount of hazardous substances that receptors are exposed to, as opposed to how much of the hazardous substances from the original sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrusion a ddition to the HRS. Since the subsurface intrusion component also focuses on exposure, the waste quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar four- tiered hierarchical approach to calculate hazardous waste quantity within occupied structures with contaminat ion. In cases where no home is subject to actual contamination, EPA is proposing to use minimum waste qua ntity factors. In situations where there is an observed release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantity factor value. This value is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and air pathways and reflects the increased exposure risk of a release within an occupied structure.

Charge Question #2: Is EPA’s approach of basing the hazardous waste quantity on the amount of contaminants that could be found in the intruded structures appropriate? If no, what alternative approach would you recommend?

Response from K. Klein

1) The hazardous waste quantity ranking is based on the assumption that a structure or structures currently exist on the site being evaluated. If this is the case at the site being evaluated, the approach seems appropriate. But it is difficult to imagine that the sampling necessary to carry this approach out can be accomplished within a 1 -2 day site inspection. Soil gas/groundwater sampling should be done prior to indoor air sampling in order to identify those substan ces to be analyzed for in indoor air (substances associated with subsurface contamination).

### 2) However, the approach does not allow for the determ ination of the hazardous waste quantity in the absence of structures but where significant hazar dous substance (VOC) contamination exists in soil/groundwater where structures could or will be constr ucted. Alternative: Provide a simple approach for estimating indoor air concentrations from measured environmental media concentrations (soil gas, groundwater) using default attenuation factors and param eters for a default structure. Provide default volume values (a default area value is provided (Table 5-19)). I could not find in the proposed regulations explicit direction on “where no home is subject to actual contamination”.

### 3. Population score Background: Within the current HRS, receptors are evalua ted in two main categories: whether they ar e exposed to 1) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting obs erved release criteria, they are identified as actually contaminated; however, if the receptors are not expose d to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially contaminated. Actual contamination is further divided into two sub-categories based on whether the hazardous substance is present

at or above a health-based benchmark. If the concen tration of the hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multiplied by a factor of 10) in scoring. If the release concentrations are less than a health-based benchmark, the receptors are identified as Level II recepto rs and are not weighted (multiplied by a factor of 1). Potential receptors are distance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to the site score.

Proposed Approach: EPA is proposing to generally use the same receptor weighting structure in the subsurface intrusion component as the one used in th e current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in the area(s) of subsurface contamination (ASC) are considered potentially contam inated (See Figure 2). The receptors in an AOE are

further differentiated based on whether the contaminant concentrations are at levels above identified benchmarks (Level I) or are at levels establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use fo r the subsurface intrusion component are:

• Screening concentration for cancer effects; and

• Screening concentration for non-cancer effects (systemic toxicants).

Consistent with the weighting of populations throughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II contaminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of targets within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential receptors within the ASC receive less weight (population multiplied by a factor of 0.1), except in cases where a sub-slab sample indicates contaminant levels are at least 10 times higher than a health-based benchmark (population is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting reflects the observation that for approximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustment applied to the health-based benchmark reflects EPA’s finding that, in such paired sampling events, the indoor air sample concentration is, on average, 10 times lower than the sub-slab sample concentration.

### Figure 2

Charge Ques tion #3: Is it appropriate to consider individuals/populations located within the area of subsurface contamination (ASC) to be at a higher relative risk in situations when sub-slab contaminant concentrations are at least ten times greater than a health-based benchmark? If no, please explain.

Response from K. Klein

This approach is consistent with the California Department of Toxic Substances Control (DTSC) vapor intrusion guidance.

### 4. Multi-story and multi-tenant structures Background: In the current HRS, multi-story and m ulti-tenant buildings are evaluated based on population associated with an actually or potentially impacted target. In the ground water pathway, all residents who are served by a well are considered subject to the actual or potential contamination of the well. In the air pathway, all residents who have an opportunity to breathe ambient air are considered subject to the actual or potential contamination of the ambient environment w ithin a distance category. All receptors within a contaminated surface water stretch are subject to the level of contamination associated with that surface water stretch. In the soil exposure pathway, receptors must be able to come in contact with areas of contamination. In determining the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/use areas within a 200 foot areal extent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multi-story (the assumption being that is reasonable for people to use the outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story/multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenant/m ulti-story building. EPA is proposing to consider all receptors exposed to actual contamination as the population inhabiting the floor of the intruded space and the population inhabiting the floor above and the floor below the intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, while also minimizing the potential for over counting (Figure 3).

### Figure 3 Charge Question #4: When calculating waste quantity and population, is it scientifically reasonable for populations in multi-story or multi-tenant structures to be evaluated based on using only the population inhabiting the intruded space and the population on the floor above and below the intruded space (For example, if contamination is found on the first floor, population from the basement and second floor would be used in the calculation. If contamination is found on the fifth floor, population from the fourth floor and

sixth floor would be used in the calculation – for fu rther explanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, what alternative approach would you recommend?

Response from K. Klein

This is a reasonably conservative approach. However, th ere is much uncertainty surrounding the stated assumptions. Therefore, there should be an in-depth discussion of this approach in the proposal Technical Support Document with references to support it.

### 5. Factor Value for Workers Background: In the current HRS, for the resident p opulation threat of the soil exposure pathway, a factor value for workers is assigned based on the total number of workers present within the area of observed contamination. These factor values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker factor va lue in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). However, since it is anticipated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamination, EPA is proposing to assign workers exposed to subsurface intrusion a higher weighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to su bsurface intrusion within the workplace than it is for workers exposed to outdoor surface contaminat ion at the workplace? If no, please explain.

Response from K. Klein

Assuming a relative risk of three times greater for indoor workers vs. outdoor workers for volatile organic chemicals (VOCs) may be an underestimate, since indoor workers would be exposed to contaminated air in a limited volume over much of their work day; whereas, contamination in outdoor air is not constrained in a limited space but is immediately diluted by atmospheric air. Other direct exposure pathways (incidental soil ingestion; dermal contact) contribute very little to uptake/intake because of the volatile nature of the chemicals under discussion in the subsurface in trusion component. The proposal Technical Support Document should discuss and provide support for any fact or chosen to reflect the greater relative risk for
indoor workers.

### CURRICULUM VITAE August 2010 

## Kimiko A. Klein

9 Noah Court Sacramento, CA 95831 (916) 422-8355

403 Main Street, Unit 312 San Francisco, CA 94105 (415) 546-6405

EDUCATION

1986 Ph.D., Comparative Pathology, University of California, Davis

1962 Medical Technology Internship, U.S. Public Health Service Hospital, Staten Island, New York

1961 B.S. with honors, Public Health Laboratory Technology, University of California, Berkeley

HONORS

2006 Superior Accomplishment Silver Team Award, Department of Toxic Substances Control

1998 Sustained Superior Accomplishment, Department of Toxic Substances Control

1982 Special Performance Award, Un iversity of California, Davis

1980 Citation for Excellence in Supervision, University of California, Davis

1979 Outstanding Service to the Laboratory, Radiobiology Laboratory, University of California, Davis

POSITIONS HELD

3/10 – Present Staff Toxicologi st Emerita, California Depart ment of Toxic Substances Control, Berkeley

6/90 – 11/09 Staff Toxicologist, California Department of Toxic Substances Control, Sacramento

10/87 - 6/90 Staff Toxicologist; Envir onmental Hazards Scientist, California Department of Food and Ag riculture, Sacramento

### 1974 - 1987 Staff Research Associate IV, Laboratory for Energy-Related Health Research, University of California, Davis

1965 - 1970 Laboratory Technician III, Radi obiology Laboratory, University of California, Davis

1962 - 1965 Laboratory Technician II, Univer sity of California, San Francisco

ACTIVITIES

1992 Membership Officer, Genetic and Envi ronmental Toxicology Association of Northern California.

2000 Secretary, Genetic and Environmental Toxicology Association of Northern California

1979-1982 Member, FDA Advisory Committee, Hematology Section of the Clinical Chemistry and Hematology Devices Panel, Washington, DC. Consumer representative to the panel.

1976-1977 Member, Task Force on Long-Term Care, Golden Empire Health Systems Agency, Sacramento

DISSERTATION

Canine Lymphohematopoiesis - June 1986

PUBLISHED PAPERS

– 17 published papers from 1967 through 1995 on hematopoiesis and toxicology The following are papers in toxicology:

1987 Klein, A. K., M. L. Nasr and M. Gold man. The effects of in vitro exposure to the neurotoxins Sarin (GB) and Soman (GD) on unscheduled DNA synthesis by rat hepatocytes. Toxicology Letters 38:239-249.

1988 Nasr, M. L., M. Goldman, A. K. Klein, and J. C. Dacre. SCE induction in Chinese Hamster Ovary cells (CHO) exposed to G agents. Mutation Research 204:649-654.

1995 Klein, A. K., J. P. Christopher. Ev aluation of crystalline silica as a threshold carcinogen. Scandinavian Journal of Work, Environment & Health 21 suppl2:95-98.

– 3 chapters on toxicology and risk assessment in books from 1993 through 2002

### The following are the chapter citations:

1993 Wade, M. J., B. K. Davis, J. S. Carlisle, A. K. Klein, L. M. Valoppi. Environmental Transformation of Toxic Me tals. In: De Novo Toxi cants: Combustion Toxicology, Mixing Inco mpatibilities, and Environmental Activation of Toxic Agents. State of the Art Reviews, Occupational Medicine. Eds. D. J. Shusterman, J. E. Peters on. Volume 8/Number 3. Hanley & Belfus, Inc. Philadelphia.

1995 Davis, B. K., A. K. Klein. Medium-specific and multimedium risk assessment. In: Toxicology and Risk Assessment, Prin ciples, Methods, and Applications. Eds. A. M. Fan, L. W. Chang. Marcel Dekker, Inc., New York.

2002 Klein, Kimiko, Marilyn Underwood. Remediation. In: Encyclopedia of Agrochemicals. Eds. Jack R. Plimmer, D. W. Gammon, N. N. Ragsdale. John Wiley & Sons, Inc. 2003.

PUBLICATIONS OF THE CALIFORNIA DEPARTMENT OF FOOD AND AGRICULTURE

1988 Oudiz, D. and A. K. Klein. Eval uation of Ethyl Parathion as a Toxic Air Contaminant. 179 pp. CDFA EH-88-5. NTIS PB90-134909.

PUBLICATIONS OF THE CALIFORNIA DEPARTMENT OF TOXIC SUBSTANCES CONTROL (DTSC)

2009 Klein, K. and D. L. Berry. Remedial Goals for Dioxins and Dioxin-like Compounds for Consideration at Califor nia Hazardous Waste Sites. Human Health Risk Assessment (HHRA) Note 2. DTSC. May 2009.

COURSES TAUGHT

1. 1990 - 1993. Risk and Decision Making Workshop. Three-day course sponsored by the US EPA Region IX and the Department of Toxic Substances Control for governmental regulatory agency pers onnel. Team instructor. .

2. 1993 - 1994. Critical Issues in Risk Assessment: Risk Assessment Guidance for Superfund and DTSC Supplemental Guidance. One-day course for staff of the Department of Toxic Substances Control. Team instructor with Dr. Brian Davis.

3. 1994. Risk and Decision Making at Petr oleum Impacted Sites. Three-day course sponsored by the San Francisco Bay Regional Water Quality Control Board for governmental regulatory agency personnel. T eam instructor with Dr. Brian Davis for the sections on risk assessment.

### 4. 1996 -1997, 2001. Environmental Toxico logy 146. Spring quarter course given at the University of California at Davis for upper division students. Team instructor for sections on topics related to regulatory risk assessment.

5. 1996, 1997. Risk Assessment Modeling: The CalTOX Model. Three-day extension course sponsored by the University of Calif ornia at Davis for interested parties. Team instructor.

6. 1996. Risk-based Cleanup: What’s A cceptable? One-day extension course sponsored by the University of California at Davis for interested parties. Team instructor responsible for the topic of calculating human health-based safe soil levels.

7. 1997. Health Risk Assessment at Hazardous Waste Sites. Two-day short course on human and ecological risk assessment princi ples at Chulalongkorn University, Bangkok, Thailand.

8. 1997, 1998. Integrated Multimedia Ex posure Modeling with Sensitivity and Uncertainty Analysis. One-day course s ponsored by the International Society of Exposure Analysis. Team inst ructor with Dr. Ned Butler.

9. 1998. Modeling Environmental Risk – Demonstration of California Toxic Risk Models. One-day course sponsored by the Harvard School of Public Health. Team instructor with Dr. Ned Butler.

10. 2000. Advanced Health Risk Asse ssment. Three-day short course at Chiang Mai University, Chiang Mai Thailand. Given al so for Pollution Control Department staff, Ministry of Science Technology and Envi ronment, at Chulalongkorn University, Bangkok, Thailand. Team inst ructor with Dr. Brian Davis.

11. 2009. Vapor Intrusion Guidance. Two-day short course on evaluating vapor intrusion into indoor air spaces from s ub-surface sources. Team instructor responsible for the topic of proper applicat ion of California Human Health Screening Levels (CHHSLs) in estimating the risk from this exposure pathway.

PRESENTATIONS

Davis, B.K., Klein, A.K., Wade, M.J., Va loppi, L.M., and Carlisle, J.S., 1994. Environmental transformation of metals and risk assessment. The Toxicologist 14:39.

Davis, B.K., Christopher, J., Wade, M.J., and Klein, A.K., 1995. Risk assessment for multiple source exposures. The Toxicologist 15:36.

Christopher, J.P., Butler, E.G., Klein, A.K., Davis, B.K., and Wade, M.J., 1996. CalTOX Stochastic Risk Assessment Compared to Standard CERCLA Methods. The Toxicologist, (Fundamental and Applied Toxicology) 30:113.

### Butler, E.G., Klein, A.K., Davis, B.K., Ch ristopher, J.P., Wade, M.J., Wong, J.J., and McKone, T.P., 1996. Use of CalTOX to Guide Site Characterization and Risk Management Decisions for Contaminated Soil. Fundamental and Applied Toxicology, (The Toxicologist) 30:113-4.

Davis B.K., Klein, A.K., and Wade, M.J ., 1998. Approaches to Screening Level Risk Assessment at California Hazardous Waste Sites. Toxicological Sciences 42:231.

Christopher, J.P., Carlisle, J.C., Davis, B.K ., Klein, A.K., Renzi, B.E., and Wade, M.J., 2000. Comparison of Updated Leadspread to Integrated Uptake, Exposure and Biokinetic Model (IEUBK) for predicting blood lead in children. The Toxicologist, Supplement to Toxicological Sciences 54:72.

Carlisle, J.C., Christopher, J.P., Davis, B.K ., Klein, A.K., Renzi, B.E., and Wade, M.J., 2000. Updated version of Cal/EPA’s Leadspr ead model for predicting blood lead in children and adults. The Toxicologist, Supplement to Toxicological Sciences 54:72.

Renzi, B., Wade, M.J., Davis, B.K., Kl ein, A.K., and Christopher, J.P., 2001. LeadBased Paint in Soil: When Worlds Collide – CERCLA Meets HUD. The Toxicologist, Supplement to Toxicological Sciences 60:422.

Davis, B.K., J.F. Beach, M.J. Wade, A.K. Klein, and K. Hoch, 2002. Risk Assessment of Polychlorinated Biphenyls (PCBs) in Indoor Air. The Toxicologist, Supplement to Toxicological Sciences 66:106. Abstract number 516.

DiBiasio, K., K. Klein, 2003. Human Health Risk Evaluation of Structural Surfaces Contaminated with Metals, presented at the Society of Toxicology Annual Meeting.

DTSC WORK GROUPS/TEAMS – I was a mem ber of the following work groups/teams involved in developing guidance or resolving issues associated with risk assessment:

2005 HERD Work Group on Environmentally Acceptable Endpoints for Lampblack and Lampblack-Impacted Soils – Polycyclic Aromatic Hydrocarbons available for dermal and ingestion absorption

2006 Cal/EPA Work Group on Use of Califor nia Human Health Screening Levels (CHHSLs) in Evaluation of Contaminated Properties

2005; 2010 DTSC Work Group on Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air

2005 HERD Work Group on Default Exposure Parameters for Non-Residential Receptors at Abandoned Mining Sites

### 2006 DTSC Voluntary Cleanup Program T eam charged to review voluntary cleanup operations and recommend changes to make the process go more quickly, more effectively and better.

2010 Co-author revising the DTSC Pr eliminary Endangerment Assessment Guidance Manual

RESEARCH INTERESTS AND SKILL SET

Toxi cologists in the Human and Ecological Risk Office of the Department of Toxic Substances Control perform and review hum an and ecological health risk assessments. Our primary focus is assessment of expos ure by humans and non-human receptors to chemicals that have been released to the environment and have the potential to cause adverse health effects. My principal scientif ic interest is alternative approaches to exposure assessment that address site-specific characteristics of locations affected by past manufacturing activities. Technical writing and risk communication are particular skills I possess. These skills are important in the clear transmittal of critiques and reviews of documents submitted to the Department and in the teaching of risk assessment to students and individuals in the community.

The following is a summary of my experience in and knowledge of environmental fate and transport.

1. 1987-88. As an environmental hazards scientist in the environmental monitoring program of the California D epartment of Food and Agriculture, I was responsible for reviewing the protocol, performance, and re sults of field experiments designed to measure residual pesticide concentrations in environmental media after legal application. I was a co-author of a report on the evaluation of ethyl parathion as a toxic air contaminant with responsibility for the sect ions on the environmental fate of this pesticide.

2. 1993-98. As a member of the team overseeing the development and use of a spreadsheet model, called CalTOX, that relates the concentration of an organic chemical in soil to the risk of an adverse health effect for a person living or working on or near the contaminated soil. I was res ponsible for writing the technical reports describing the model for the California D epartment of Toxic Substances Control (DTSC). CalTOX was developed by the University of California and has been extensively peer-reviewed. The spreadsheet model consists of two parts. The first part uses equations based on conservation of mass and chemical equilibrium to predict the time-dependent concentrations of a chemical in the eight environmental compartments of air, surface water, groundwater, three soil layers, sediment, and plants at a site. The second part relates those calculated chemic al concentrations in environmental media over time to concentrations in personal ai r, tap water, food, household dusts, etc., thereby combining environmental fate and transport of the chemical to potential exposure to the chemical by human receptors.

### 3. 1996-98. I was part of a DTSC team t eaching courses that emphasized multi-media exposure modeling as a screening tool in human health risk assessment. Environmental fate processes were discussed in depth in these courses.

4. 2005- present. I was part of a DTSC team writing guidance on evaluating the intrusion of subsurface vapors intruding into indoor air. This evaluation is based on a spreadsheet model that considers diffusion and advective forces in the transport of volatile chemicals in sub-surface soil and/or groundwater to indoor air spaces. Thismodel is called the Johnson and Ettinger Model and has been extensively peerreviewed and modified by the DTSC for use in human health risk assessment.

### Dot Lofstrom

Section Chief, Geological Services Unit
California Environmental Protection Agency

– Department of Toxic Substances Control (DTSC)

8800 Cal Center Drive Sacramento, California 95826

• Lead Author of Vapor Intrusion Mitigati on Advisory (DTSC 2011)

• Co

‐ Author of Advisory ‐ Active Soil Gas Investigations (Cal/EPA –expected publication date February 2012)

• Technical Editor for the Guidance for the Evaluation and Mitigation of Subsurface Vapor
Intrusion to Indoor Air (Vapor Intrusion Guidance) (DTSC 2011).

M.S.

– Geology, University of Missouri, 1988

B.S.

– Geology, Missouri State University, 1981

Professional Ge ologist #7022

Summary of Work Ex perience : 24 years with primary emphasis on soil and groundwater investigations
under RCRA and CERCLA. Background includes State government, consulting, federal government (Department of the interior) and academics (Arizona Western College).

Summary of Vapor Intrusion Experience : Actively working on vapor intrusion guidances at DTSC since 2008; presented papers on DTSC guidance at Air and Waste Management Association (San Diego 2009),
National Brownfield Association (Sacramento 2009), and the Batelle conference in Monterey (2010).

2009 to present

DTSC, Sacramento CA ‐ Supervisor for Cal Center Geological Services Unit. As a supervisor, provide
technical and professional leadership to nine registered geologists working on investigation and
remediation of soil, soil gas, and groundwater within the State of California, under the RCRA and CERCLA

processes. Serve as Vapor Intrusion/Soil Gas Collection Specialist within DTSC.

2005 to 2009

DTSC, Sacramento CA ‐ Senior Engineering Geologist .Remedial Project Manager for the NPL site Naval Air
Station

‐ Alameda, California.Worked closely with EPA RPM Anna

‐ Marie Cook, San Francisco Region 9, following the CERCLA process from remedial investigation through the Record of Decision and Remedial Design.Reviewed and commented on technical documents and represented DTSC in public meetings.

2001 to 2005

DTSC, Sacramento CA ‐ Engineering Geologist

. Provided geologic support the RCRA sites, primarily
focused on post

‐ closure permits or corrective action for treatment, storage and disposal facilities.

2000

– 2001

San Joaquin County, Stockton CA

– Registered Geologist .Provided technical guidance and leadership for

six registered environmental health specialists, ensuring proper investigation and remediation of leaking underground storage tanks.Dot Lofstrom (page 2)

1998

– 2000

Tetra Tech, EMI, Sacramento CA

– Senior Environmental Geologist .Remedial Project Manager for Naval Computer and Telecommunication Station ‐ Stockton. Lead investigator for ten landfill sites, collecting
relevant soil and groundwater data, and managing writing/production of remedial investigation reports for U.S. Navy.

1993 ‐ 1998

Arizona Western College, Yuma AZ

– Professor of Environmental Technology

. Lead faculty instructor
and creator of Department of Environmental Technology, a program designed to give students a practical background to prepare them for work as environmental technicians. Taught courses in
Environmental Regulations, Sampling and Analysis, Hazardous Waste Management, and Physical Geology.

1991

‐ 1993

Department of Defense (USBR and BLM), Yuma AZ

• USBR ‐ Hydrogeologist. Responsible for installation and development of large

‐ diamater irrigation and drinking water wells.

• BLM –District Geologist. Responsible for administering the Minerals program in the Yuma District, reviewing mining and reclamation plans.

1988

– 1993

IT Corporation, Irvine CA

– Assistant Project Scientist

. Responsible for investigation of leaking underground storage tanks and pesticide contaminated sites. Conducted site investigations, analyzed
soil and groundwater data, and wrote subsequent reports.

# Peer Reviews

Henning Larsen

(Oregon DEQ)

• Charge Questions Comments

• CV

• COI Certification

### Peer Review Charge for: U.S. Environmental Protection Agency (EPA). Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System ; 40 CFR Part 300; EPA-HQ-SFUND-2010-1086; FRL_XXXX-X (review draft).

Background The U.S. Environmental Protection Agency (EPA) is proposing to include a s ubsurface intrusion (SsI) component to the Hazard Ranking System (HRS). S ubsurface intrusion is the migration of hazardous substances from the unsaturated zone and/or the surf icial ground water into overlying structures. The HRS is the principal mechanism the EPA uses to evaluate site s for placement on the National Priorities List (NPL). The subsurface intrusion component addition (this add ition) would primarily expand the number of available options for EPA and state and tribal organizations pe rforming work on behalf of EPA to evaluate potential threats to public health and the environment from releases of hazardous substances.

This addition will allow the HRS evaluation to directly consider human exposure to hazardous substances that enter building structures through subsurface intrus ion, and thus enable sites with subsurface intrusion contamination to be evaluated for placement on the NPL. This addition will make the HRS more accurate in assessing a site’s relative potential risk. The Agency is not considering changes to the remainder of the HRS except for minor updates reflecting changes in terminology related to revised toxicological parameters. This proposed regulatory change does not affect the status of sites currently on or proposed to the NPL.

Expertise Required The peer review panel for U.S. EPA’s Proposed Rule: Addition of a Subsurface Intrusion Component to the Hazard Ranking System should include expertise in:

State Environmental Program Panelist: Panelist must have strong technical experience and working knowledge of policy and technical issues (e.g., mitigati on and remediation) related to the topic of vapor intrusion. Expertise in hydrogeology, chemistry, knowledge of public health risks associated with indoor air threats, and the subsurface migration of volatile h azardous substances is necessary. Knowledge of recent developments in vapor intrusion technologies and research is required, in addition to working knowledge of state vapor intrusion response programs. Field experience conducting vapor intrusion investigations, while not required, is highly desirable. Experience related to conducting field investigations for the purpose of listing sites on the NPL and/or experience working with the HRS to evaluate sites for inclusion on the NPL is highly recommended, but not necessary.

Peer Review Charge Questions

1. Potential for subsurface exposure (intrusion) into occupied structures Background: The current HRS evaluates the likelihood of a rele ase of a hazardous substance when an actual release has occurred through either chemical analysis or direct observation. The current HRS also evaluates the potential for a release to occur within the ground water, surface water and air pathways (see section 2.3 of the current HRS). The potential for a release is determined by the consideration of pathway specific factors that aid the site evaluator in predicting whether a release to the pathway is likely to occur. These factors are based on containment features of the source of contamination (whether or not hazardous substance can get out), route characteristics specific to each pathway (how far hazardous substances could migrate based on knowledge of site conditions) and include physical/chemical properties of the hazardous substances being evaluated (how the hazardous substances act in the environment).

### Proposed Approach: EPA is proposing a parallel approach for evaluating potential and actual exposure of

intruded hazardous substances for the subsurface intrusi on addition to the HRS. In determining which route characteristics are appropriate for evaluating potential exposure to subsurface contaminants, EPA examined present modeling methods such as the Johnson-Ettinger m odel and also considered multiple lines of evidence approaches which estimate the levels of contaminant exposure based on numerous route characteristics. In addition, EPA examined the relationship between these factors to determine which have the greatest influence on the likelihood that an exposure would occur, and then incorporated these factors within its proposed approach. EPA also gave careful consideration to ensure that the data necessary to obtain route

characteristic factors could be measured or calculated on a site-specific basis and in a manner consistent with current HRS evaluations. Based on the Agency’s analysis, the following three factors for which sufficient site-specific information could be collected during a site inspection represented the greatest impact on the potential for exposure: (1) depth to contamination; (2) vertical migration; and (3) vapor migration potential (see Figure 1).

Figure 1

### Charge Question #1 : Is EPA’s proposed approach scientifically reasonable for evaluating and assigning proportional weightings for the following when evalua ting potential for exposure? If no, what alternative approach would you recommend?

a. Consideration of the construction/structure type for which sufficient site-specific information could be collected during a site inspection for the occupied structure;

Potential for Exposure Equation

I agree generally with the mathematical set up of the equation (2a*(2b+2c+2d) and the decision to make the potential for exposure a product (in the mathematical sense) of a building’s characteristics and the subsurface conditions that lay beneath it. It mimics the two compartment model that many professionals and researchers conceptualize the vapor intrusion pathway to be. Furthermore, I believe it accurately replicates the “breaking” of the pathway by assigning a value of 0 to structures that employ demonstrated effective vapor

control measures.

Overall, the term for the structure (a) ranges from 0-10 while the subsurface term (the sum of b+c+d) ranges

from 1-50

. Ideally the subsurface term should range as low as zero to reflect the absence of vapor intrusion risks associated with high molecular weight semi-volatile compounds like cPAHs, PCBs, and most pesticides. Thus, either term could have a zero value and the exposure pathway would then be considered broken or incomplete under two conditions: 1) in cases where a demonstrated effective vapor control technology is used, and 2) when a contaminant has sufficiently low volatility.

Mathematically, this could be accomplished by multiplying the Depth to Contamination (b) and Vertical Migration (c) terms by the Vapor Migration Potential (d) term. Thus a zero Vapor Migration Potential value would yield a zero for the entire Potential for Exposure factor. If the equation is changed in this way, the range in values for the Depth to Contamination and Vertical Migration terms would likely have to be adjusted so that Potential for Exposure results fall into the intended range of values (0-500).

Table 5-12 Structure Containment

I suggest revisions to Table 5-12 with respect to the number of building types distinguished, their description, and their value assignments.

• There does not appear to be a category that describes maybe the commonly encountered type of residence: a slab-on-grade constructed home with no apparent open preferential pathways or vapor migration barrier system. This is a significant o mission that I believe will lead to confusion in categorizing structures. On the scale of 1-10 that is used for this factor I would assign this category of building a value of 9. It is vulnerable to vapor intrusion, but it is not the most vulnerable of

residential structures.

• Homes that are underlain by a combination of base ment and crawl space, and which do not have any form of vapor mitigation system, should be described as such and placed in Category 2. This is a common type of residential construction and it would be an omission to leave it out of Table 5-12.

### With this type of building there usually is a 4-5 ft high stem wall that separates the crawl space from the basement and generally there is no seal or a ve ry poor seal between the crawl space and basement areas. This allows vapors to freely migrate into the basement and living spaces making these homes some of the most sensitive and vulnerable with respect to vapor intrusion. This type of structure should be assigned a value of 10 in Table 5-12.

• In my experience, residences that are completely underlain by vented crawl spaces generally have fairly small attenuation factors and their vulnerability to vapor intrusion is considerably less than other building types. This was observed at a chlorinated solvent release at the Eugene Rail Yards site in Eugene, Oregon. At this site, crawl space concentration showed a broad range of attenuation factors and a poor correlation to soil gas values. It appeared crawl space concentrations were most influenced by background and insignificantly by soil gas that spanned a range of PCE concentrations. Based on my experience I would assign a value of 6 rather than 8 to this type of construction. However, I acknowledge that nationally there may be regional/climatic differences that affect the degree of communication between the crawl space and the overlying building and justify the value of

8.

• Evidence of biogas, inert gases. Is this referring to methane and radon? Typically this type of information is not available for relatively short inspections.

b. Distance between occupied structure and depth of contamination; and

At the depths beyond the 0-10 ft range presented in Table 5-13 chemical diffusion is generally considered to be the dominant transport mechanism. Diffusion and diffusive flux is typically described using Fick’s Law J= -D(dc/dz). Using Fick’s Law and assuming 100 ug/m 3 

### at the source and zero in indoor air, concentration gradients as a function of depth are plotted below.

### Using this approach and assuming a Depth to Contamination value of 10 for a source 10 ft below the occupied base of a structure, 20 ft would then have a value of 5, 50 feet would have a value of 2, 100 ft a value of 1 and 150 ft of 0.66. Since this term is evaluating the strength of diffusive flux in the subsurface and not attempting to consider geologic heterogeneity, the values should be based on Fick’s Law of diffusion which has been empirically demonstrated to be accurate in numerous column tests of porous media; this is unless there is sufficient empirical field data that supports the numerical assignments in Table 5-13.

Considering Depth to Groundwater Contamination and Depth to Soil Vapor Contamination Equivalently

An important concern in the assignment of Depth to Contamination values under section 5.2.11.2.2 is the approach treats groundwater and soil gas as equivalent media and at any given site there depths are presumably comparable. However, it isn’t an either or situation, if there is a groundwater plume of contamination at the water table, there will be corresponding soil gas contamination above it and by definition the soil gas will always be shallower than the groundwater contamination. Depending on where the soil gas measurement is taken it could be 20, 30, 50 ft or more shallower than the depth the groundwater contamination is measured at. Thus, the depth to contam ination that is entered into this table may in large part be a consequence of which media was sampled and not the actual site conditions.

I ran one of our bigger vapor intrusion sites (Tarr Oil, Portland, OR) through the Potential for Exposure calculation and it scored a 380 based on the initial groundwater data, and a 500 based on soil gas data. The location of the measurement also affects assignment of the Vapor Migration Potential value. The depth of measurement and choice of media to sample potentially introduces a bias that should ideally be eliminated

from the calculations.

c. Evaluation of the vertical migration factor ba sed on the thickness and porosity/permeability of geologic materials in the interval between the lowest point of an occupied structure and the highest known point of hazardous substances in the subsurface.

Assignment of Vertical Migration Factor Values

Vertical migr ation values for soils assigned a porosity/permeability value of 4 ( clays, low permeability till, unfractured igneous rocks etc.) appear to be excessively high when compared to the values of other soils and thicknesses in Table 5-15 and relative to values assigned to the Depth to Contamination factor. True clays and unfractured igneous rocks have extremely low e ffective porosities and if they have any appreciable thickness should act as a virtually complete barrier to vapor transport. The only exception would be if the clays were or had been desiccated leaving fractures for preferential flow.

It is difficult to say the 0-5 ft thickness value of 15 for soils assigned a porosity/permeability value of 4 is disproportionately high given the thickness ranges down to zero. However, I suggest revising the value for the 5-10 ft thickness to 8 rather 12, and the 10-20 ft thickness range 6 rather than 9 and the 20-50 ft range to 3 rather than 6 and the 50-100 ft and 100-150 ft ranges both should be 1 . I cannot think of a more restrictive barrier to vapor transport than 50-100 ft of true clay.

The values in Table 5-15 applied to soils assigned a permeability/porosity value of 1-3 appear appropriate.

### Although not discussed, effective porosity for gas transport (diffusion rates through water-filled pore spaces are generally 100,000x or more lower than through air-filled) is highly sensitive to moisture content in the soil and I assume this consideration is embedded in the values of Table 5-15. Finer-grained soils typically retain a higher moisture content that further reduces effective porosity. This degree to which soils are saturated is largely a consequence of annual precipitati on rates and their seasonal distribution. Therefore, for identical soils it’s anticipated that there would be regional differences in the vertical migration factor. Ideally the moisture content factor would be considered in the scoring, however, there may be insufficient information to confidently develop values.

### 2. Hazardous Waste Quantity Background: In the current HRS, the hazardous waste quantity factor reflects the risk consideration related to the magnitude and duration of either the release for ground water, surface water, and air pathways, or the exposure for the soil exposure pathway (see section 2.4.2 of the current HRS). Hazardous waste quantity is evaluated for all four pathways. At each site evaluated, EPA uses a four-tiered hierarchy for calculating the hazardous waste quantity that is based on (1) constituen t quantity; (2) waste stream; (3) volume; and (4) area of the sources of hazardous waste at the site. EPA uses minimum waste quantity factors when there is insufficient information to estimate hazardous waste quantity. In the ground water, surface water, and air pathways, the HRS evaluates the total quantity of hazardous substances available to migrate from the original sources (how much has migrated and how much can be released in the future). In the soil exposure pathway, the hazardous waste quantity does not include the total amount of hazardous substances in all site sources, but rather is based on the amount of hazardous substances to which a receptor can be exposed where actual contamination has been documented. In other words, for the soil exposure pathway, the risk posed by a release of hazardous substances is directly related to the amount of hazardous substances that receptors are exposed to, as opposed to how much of the hazardous substances from the original sources may migrate to the receptors.

Proposed Approach: EPA is proposing a parallel approach to the soil exposure pathway to calculate hazardous waste quantity for the subsurface intrusion a ddition to the HRS. Since the subsurface intrusion component also focuses on exposure, the waste quantity factor value for this component should also reflect only the amount of hazardous substances that people actually are exposed to (the amount present in occupied structures). EPA is proposing to use a similar four- tiered hierarchical approach to calculate hazardous waste quantity within occupied structures with contaminat ion. In cases where no home is subject to actual contamination, EPA is proposing to use minimum waste qua ntity factors. In situations where there is an observed release within a structure above benchmarks (Level I), a default value of 100 is proposed for the hazardous waste quantity factor value. This value is not used in the current soil exposure pathway, but is consistent with the ground water, surface water, and air pathways and reflects the increased exposure risk of a release within an occupied structure.

Charge Question #2: Is EPA’s approach of basing the hazardous waste quantity on the amount of contaminants that could be found in the intruded structures appropriate? If no, what alternative approach would you recommend?

I disagree with the proposed approach to calculating hazardous waste quantities for the subsurface intrusion component. Compared to soil and water, air is a much less dense medium and as a consequence, for equivalent risk levels between various media, it typically contains much less contaminant mass. Essentially airborne contaminants can generate equivalent human health risks to those resulting from contact with other media, although with far less mass. For example, the St ate of Oregon assumes benzo(k)anthene has an oral slope factor of 0.073 and has calculated a residential soil screening level of 6.2 mg/kg (equating to 1x10-6 risk). Assuming a 5000 ft 2 

### property that is 70% land 30% impervious surface, a 1 foot thick layer of soil contaminated up to the screening level would contain approximately 1,190 grams of benzo(k)fluoranthene. In comparison, a 1300 ft 2 

### residence with vinyl chloride (inhalation slope factor of 0.031) contamination at a concentration 0.14 ug/m 3 

### (equivalent to 1x10 -6 

### risk) has 0.000047 grams in the indoor air at any one time.

### Assuming an air exchange rate of 6 exchanges/day, approximately 3.1 grams would have moved through the home over a 30 year period of time. Assuming an identical toxicity and slope factor to that of benzo(k)fluoranthene, the mass of vinyl chloride in the air over the 30 year period is 6.3 grams for the equivalent risk. Humans contact and take up air contaminants much more efficiently than contaminants in water or soil, therefore, it requires far less mass for equivalent risk.

Using Table 2-6 (pg. 22) and the methods outlined in 5.2.1.2.2 to assign a Hazardous Waste Quantity Factor value, it is likely most vapor intrusion sites would ge t a quantity of 1 unless an exposure is documented then it defaults to 100. It appears very unlikely any VI site would have hazardous quantity factor larger than 100. This results in relatively low Waste Characteristic Factor values compared to what can calculated for other media and pathways. In this respect it appears to underestimate the risk of the subsurface intrusion pathway relative to others.

Suggested Alternative Proposed HRS Method of Estimating Hazardous Waste Quantity

Quantify and include contaminant sources in the subsu rface in addition to the contam ination found within the buildings. These sources constantly feed the contaminat ion within the buildings and so could be legitimately included in the inventory of waste quantities. For th is particular factor, the change would make the magnitude/mass of sources of vapor intrusion more comparable to those contaminating other media.

### 3. Population score Background: Within the current HRS, receptors are evalua ted in two main categories: whether they ar e exposed to 1) actual contamination; or 2) potential contamination (see section 2.5 of the current HRS). If receptors are exposed to contaminant levels meeting obs erved release criteria, they are identified as actually contaminated; however, if the receptors are not expose d to contaminants that meet the observed release criteria but are within the target area being evaluated, they are considered potentially contaminated. Actual contamination is further divided into two sub-categories based on whether the hazardous substance is present

at or above a health-based benchmark. If the concen tration of the hazardous substance released at the receptor is greater than a health-based benchmark, the receptors are identified as Level I receptors and are weighted (multiplied by a factor of 10) in scoring. If the release concentrations are less than a health-based benchmark, the receptors are identified as Level II recepto rs and are not weighted (multiplied by a factor of 1). Potential receptors are distance/dilution weighted; in other words, the farther away a receptor is located from a source, the less the population contributes to the site score.

Proposed Approach: EPA is proposing to generally use the same receptor weighting structure in the subsurface intrusion component as the one used in th e current HRS. Those receptors in the area(s) of observed exposure (AOE) are considered actually cont aminated, and those in the area(s) of subsurface contamination (ASC) are considered potentially contam inated (See Figure 2). The receptors in an AOE are

further differentiated based on whether the contaminant concentrations are at levels above identified benchmarks (Level I) or are at levels establishing a release but below identified benchmarks (Level II). The benchmarks that EPA is proposing to use fo r the subsurface intrusion component are:

• Screening concentration for cancer effects; and

• Screening concentration for non-cancer effects (systemic toxicants).

Consistent with the weighting of populations throughout the HRS, the proposed subsurface intrusion component will weight targets within the AOE subject to Level I contaminant concentrations by a factor of 10 and weight targets subject to Level II contaminant concentrations by a factor of 1.

EPA is proposing to evaluate the weighting of targets within the ASC based on sub-slab, soil gas, and/or ground water samples. Potential receptors within the ASC receive less weight (population multiplied by a factor of 0.1), except in cases where a sub-slab sample indicates contaminant levels are at least 10 times higher than a health-based benchmark (population is multiplied by a factor 0.75). The value of 0.75 was determined based on an evaluation of paired data when both a sub-slab and indoor air sample were collected. The 0.75 weighting reflects the observation that for approximately 80 percent of the sampling events where contamination was detected in the sub-slab, contamination was also detected in the indoor air sample. The order of magnitude adjustment applied to the health-based benchmark reflects EPA’s finding that, in such paired sampling events, the indoor air sample concentration is, on average, 10 times lower than the sub-slab sample concentration.

### Figure 2

Charge Question #3: Is it appropriate to consider individuals/ populations located within the area of subsurface contamination (ASC) to be at a higher re lative risk in situations when sub-slab contaminant
concentrations are at least ten time s greater than a health-based benchmark? If no, please explain.

An obvious answer to the Charge Question #3 is: yes, in general occupants of buildings where sub-slab concentrations exceed 10x a health-based benchmark are at higher risk relative to occupants of buildings with sub-slab concentrations that are less than this value. However, the scheme for weighting individual targets/receptors is crude in the ASC, does not appear consistent with the results of EPA’s compilation of paired sub-slab and indoor data, and potentially underestimates population risks.

As described in sections xxxx of the draft HRS rule revisions, for targets/receptors occupying buildings over an ASC and where subslab contaminant concentrations exceed 10x the benchmark screening level should assigned a weighting of 0.75. The explanation given is that the review of the compiled paired data indicate 80% of the time a subslab concentration exceeds 10x its respective health based benchmark, the contaminant

is detected in indoor air.

• Why wasn’t a value of 0.8 used instead 0.75 since the correlation described above was observed 80%

of the time?

• 0.75 is used in all where a subslab VOC concentration greater than 10x its corresponding healthbased benchmark has been observed within the AS C. However, subslab VOC concentrations at many sites are routinely observed at levels from 100-100,000 times their corresponding benchmarks. Yet in the proposed HRS scheme for weighting targets, irrespective of the concentration observed,

### any time it exceeds 10x the benchmark a value of 0.75 is used. Using a single value (such as 0.75) may be reasonable for weighting receptors when s ubslab levels are just 1-2 orders of magnitude above benchmark values, and indoor concentrations are likely detectable but below benchmark values. However, as subslab contaminant levels increase, eventually a concentration threshold is crossed where the results of EPA data compilation indicate the probability of exceeding a benchmark value in indoor air is very high. For these cases assigning a weighting factor that is closer to10 is more appropriate.

The proposed target weighting approach may introduce a low bias to population risks, particularly at sites where the primary medium sampled is subslab and not indoor air. soil gas and not

• It is not clear from the rule revision whether the appropriate weighting for targets within the ASC is based on the maximum observed subslab concentration or whether some form of average value is considered (i.e. arithmetic mean, UCL, etc.) My recommendation, since this is a screening process, would be to use the maximum subslab concentration observed, and that this expectation should be specified in the rule if it isn’t already.

• The EPA database on paired subslab and indoor air data has been reviewed by many states and individual practitioners. Statistics have been performed on both filtered and unfiltered data. The filtering was done in an effort to eliminate the influence of ambient background concentration on calculated attenuation factors. EPA has recognized the need to perform the data filtering to remove outlier attenuation rates. A strategy that Oregon DEQ used in an attempt to separate out background influences was to only consider data from sites with strong sources, for examples sites with subslab concentrations greater than 1000 ug/m 3



### .

The results of the data analysis indicate unfiltered paired subslab-indoor air data had an average attenuation factor of 0.003 and median value of ap proximately 0.002. An analysis of highly filtered similar to data by ODEQ produced an average attenuation factor of 0.0007 and a median value of 0.0002. Thus the statement that approximately half of the vapor intrusion sites had an average attenuation factor of 0.1 is not supported by EPA previous analysis of VI data.Derivation of Attenuation Factors

1 , 0 0 0

, 0 0 0

1 0 0

, 0 0 0

1 0

, 0 0 0

1 , 0 0 0 1 0 0 1 0 1 0

. 1 0

. 0 1 100,000

10,000

1,000

100

10

1

0.1

0.01

Subslab vapor (ug/m3)Attenuation Factor Attenuation Factors vs. Subslab Vapor Concentration

A verage 352 10th 680 25th 222 50th 33 75th 3.2 90th 1.1 Percentile A F Value

Deriving Attenuation Factors

1,000,000 100,000 10,000 1,000 100,000

10,000

1,000

100

10

Subslab Vapor Concentrations >1,000 ug/m3Attenuation Factor Attenuation Factors vs. Subslab Vapor Concentration (High Range)

Average 1,558 10th 3,324 25th 1,348 50th 516 75th 196 90th 125 Percentile AF Value

ODEQ, March 2010 

### Recommendation

Based on: statistical analyses of the EPA Database, and the recognition that it does not necessarily populated by the most sensitive structure types, I recommend that within defined ASCs assign a target weight factor of:

• 0.1 to occupants of buildings with subslab contaminant concentrations less than 50x the health-based

benchmark value.

• 1 to occupants of buildings with subslab contaminant concentrations between 50x-500x the healthbased benchmark value.

• 10 to occupants of buildings with subslab contaminant concentrations greater than 500x the healthbased benchmark value

### 4. Multi-story and multi-tenant structures Background: In the current HRS, multi-story and m ulti-tenant buildings are evaluated based on population associated with an actually or potentially impacted target. In the ground water pathway, all residents who are served by a well are considered subject to the actual or potential contamination of the well. In the air pathway, all residents who have an opportunity to breathe ambient air are considered subject to the actual or potential contamination of the ambient environment w ithin a distance category. All receptors within a contaminated surface water stretch are subject to the level of contamination associated with that surface water stretch. In the soil exposure pathway, receptors must be able to come in contact with areas of contamination. In determining the likelihood a person will come in contact with areas of contamination, the HRS uses a 200 foot rule (see section 5.1.3 of the current HRS) because it is reasonable to assume that that a person will walk/use areas within a 200 foot areal extent of their residence/property. The 200 foot rule is used regardless of whether a building is multi-tenant or multi-story (the assumption being that is reasonable for people to use the outside of their properties).

Proposed Approach: EPA is proposing to evaluate multi-story/multi-tenant buildings utilizing a similar approach as soil exposure, limiting the receptors to t hose individuals that reasonably can be exposed to subsurface intrusion within an occupied multi-tenant/m ulti-story building. EPA is proposing to consider all receptors exposed to actual contamination as the population inhabiting the floor of the intruded space and the population inhabiting the floor above and the floor below the intruded space when calculating waste quantity and population. EPA considers that this approach will more accurately reflect risk to both actual and potential receptors, while also minimizing the potential for over counting (Figure 3).

### Figure 3

Charge Question #4: When calculating waste quantity and population, is it scientifically reasonable for populations in multi-story or multi-tena nt structures to be evaluated based on using only the population inhabiting the intruded space and the population on the floor above and below the intruded space (For example, if contamination is found on the first floor, population from the basement and second floor would be used in the calculation. If contamination is found on the fifth floor, population from the fourth floor and sixth floor would be used in the calculation – for further explanation, see detailed discussion in above paragraph “Proposed Approach”)? If no, what alternative approach would you recommend?

Regarding the Calculation of Waste Quantity

See comments and responses to Charge Question #2 In the above scenario, if level I and level II exposures are observed on the first floor I would assign level I values to the basement dwellings also. They are overwhelming the most sensitive locations and having a reverse gradient scenario as depicted, wher e higher concentrations overlie lower concentrations would be very unusual for a VI site. A more likely explanation for this type of observed distribution would be simply being temporal variability in indoor air levels. I would weight the occupants

of the first floor based on the

concentration ob served in the

basement. These residences and their occupants may be under weighted just because

of the absence of direct observations – to remedy this

use the EPA database to make

educated inferences of exposure levels In this contaminant distribution, I

would assume all basement

residences are Level I due to error and uncertainty from temporal

variabilit y of indoor air q ualit y

### Regarding Assumptions and Weighting of Occu pants/Targets in Multi-Family Residences

Some comments are made directly on the Figure 3 – see boxed text. Aside from those suggested modifications, the general scheme looks appropriate.

Regarding the Weighting of Population Targets in AOE

In my opinion the weighting is disproportionately influenced by data type – specifically the difference in weighting directly observed impacts as compared to inferred impacts based on subslab sampling. Whereas an individual or population directly observed (through indoor air sampling) to be exposed to levels above the health-based benchmark is indoor exposure directly observed to be over a benchmark is assigned

The weighting of targets/receptors exposed to Leve l 1 contamination 10x higher than those exposed to Level II concentrations by a factor of 10, coupled with the recognized temporal variability in indoor air concentrations (See Paul Johnson’s recent work at Hill Air Force Base, Arizona) could produce significant swings in the population score that are more artifacts of when the sampling occurred than true differences in the magnitude of the average VOC exposure. The concern regarding accurately characterizing indoor exposure levels is particularly relevant if site inspections are conducted and indoor air concentrations measured, within a short 2-3 day period.

Potential Ways to Mitigate Errors and Uncertainties

Two ways to mitigate this uncertainty and potential error is to characterize exposure levels using ambient air sampling methods that accommodate long sampling periods, or alternatively increase the number of (shorter period) air samples that target meteorological conditions particularly conducive to vapor intrusion. In short, use sampling technologies are approaches that provide better representations of long term exposure levels.

A different approach would be to apply a scheme that has more than two designations for confirmed exposure levels. Perhaps the value 1 for detected/observed exposures that are <0.5x the benchmark health value, a value of 3 for values 0.5 -1.0 x the benchmark value, and 10 for those occupying buildings with exposures greater than the benchmark value.

Weighting of Population Targets in ASC

In the proposed approach for weighting target populations within the ASC it appears there is a disproportionate undervaluing of susbslab data relative to indoor data. Under the proposed scheme, subslab concentrations greater than 10x the health-based benchmark value would weighted with a factor of 0.75 (weighted slightly less than a level II exposure) irrespective of the specific concentration measured. EPA compiled a large database that provides opportunities for robust statistical analyses including the derivation of attenuation rate percentiles and confidence intervals. This information should be used to help appropriately weight targets where only subslab data is available. For example, using unfiltered statistics the
50 th 

### percentile attenuation factor is 0.03, thus it can be conc luded that if subslab levels exceed benchmarks by a factor of 33 or greater then there is 50% chance occupants are being exposed to levels above the corresponding health-based criteria and that the appropriate weighting is 10 rather than 0.75.

### In section 5.2.1.3.2.3, the proposed rule indicates subsla b data and crawlspace data will be similarly evaluated and weighted. The implies the data types are equivalent, however, EPA and others have generally assumed the attenuation factor between the crawl space and the residence interior should be assumed 1and thus is a reasonable surrogate for actual indoor air data . So, this would suggest detection of COCs below benchmark values in the crawl space should be weighted under the proposed scheme at a value of 1 and that if concentration exceeds benchmark values in the crawl space the appropriate weighting would be 10.

In general there appears to be a undervaluing of susbslab data, even when that is the only type of data available. However, susbslab data may be the primary type of data available at a site and the population component of the scoring may be biased low as consequence. Thus, at any given site, the scored risk may be substantially lower if the primary data source is subs lab measurements than compared to the same site if the primary source of data was indoor measurements.

Recommendation

Use EPAs database of paired subslab and indoor air data to perform more refined weighting of targets in an ASC. Ideally, the weighting would relate to the probability a Level I or Level II exposure is occurring based
on subslab data.

Additional Comment

The example scenario described in the Charge Question #4 is highly unusual contamination found on 5 th



### floor consider tenants on 4 th 

### and 6 th 

### floors. Under this scenario I would expect all floors beneath the 4 th 

### floor to be considered and actually most of them contaminated. Overall, it’s an unrealistic scenario and the actual proposed rule indicates all floors beneath the observed exposure would be considered in the calculations, as they should be.

5. Factor Value for Workers Background: In the current HRS, for the resident p opulation threat of the soil exposure pathway, a factor value for workers is assigned based on the total number of workers present within the area of observed contamination. These factor values range from 0 to15, depending on the number of workers exposed to outdoor contamination (see section 5.1.3.3 of the current HRS).

Proposed Approach: EPA is proposing to mirror the procedures for the resident population threat in the soil exposure component when assigning a worker factor va lue in the subsurface intrusion component (see Table 5-4 in section 5.1.3.3 of the current HRS). However, since it is anticipated that workers spend a larger percentage of their time indoors and therefore may be more exposed to contamination resulting from subsurface intrusion than to outdoor soil (or other surface) contamination, EPA is proposing to assign workers exposed to subsurface intrusion a higher weighting (i.e., factor values ranging from 0 to 45).

Charge Question #5: Because of longer exposure times indoors, is it reasonable to assume that the relative risk is three times greater for workers exposed to su bsurface intrusion within the workplace than it is for workers exposed to outdoor surface contaminat ion at the workplace? If no, please explain.

I agree with the proposed weighting for workers. Generally, workers do spend more time indoors and that this pathway is more likely to be complete.Henning Larsen, R.G.

2805 NE 28 th Avenue Portland, OR 97212 (503)281

‐ 4770

Current Employer : Oregon Department of Environmental Quality, 2020 SW 4 th Avenue, Suite 400, Portland, Oregon. Ph: 503

‐ 229

‐ 5527. Supervisor: Bruce Gilles (503

‐ 667

‐ 8414 x55009)

Education: B.A. in Geology, Humboldt State University, Arcata, CA; M.S. in Civil Engineering,
Oregon State University, Corvallis, OR.

Certifications: Registered Geologist, State of Oregon

Work History : 1987

‐ 1989

– Geologist, Newmont Mining Corporation

1992

– G eologist, Oregon Health Division

1992

‐ 1994 ‐ Hydrogeologist, Oregon Department of Environment a l Quality

1994

‐ 1998

– Cleanup Project Manager, Oregon Department of Environmental Quality

1998

‐ current ‐ Senior Hydrogeologist, Oregon Department of Environmental Quality

Current Duties/Responsibilities : Develop and provide senior level review of hydrogeological
investigations; develop statewide policy, guidance and rule recommendations for the State of Oreg on Cleanup Program; Agency expert on contaminant fate and transport modeling; represents DEQ at hearing, public meetings, and conferences to explain the bases for soil, soil vapor, and groundwater

‐ related cleanup requirements.

Professional Work Groups

Participant in EPA Groundwater Forum since 2007

Vapor Intrusion Related Gu idance Work

1996

– co

‐ author of State of Oregon Risk

‐ Based Corrective Actio n for Petroleum Cleanups

. Document

used J&E models to assess indoor vapor intrusion and outdoor volatilization pathways.

1999

– co

‐ author of State of Oregon Risk

‐ Based Decision Making at Petroleum Cleanup Sites. Document

used J&E level models to assess indoor vapor intrusion.

2006 –author of Guidance for Managing Hazardous Substance Air Discharges From Remedial Systems

2010

– co

‐ author/primary author of Stat e of Oregon Guid ance for Assessing and Remediating Vapor

Intrusion in Buildings.Vapor Intrusion Training Given

February 2003

– Developed and presented Risk

‐ Based Decision Making training including training on VI pathway, State of Oregon

November 2007

– Developed and presented 2

‐ day course on vapor intrusion pathway for the Northwest

Environmental Training Center (NWETC). I gave the 2

‐ day course three separate times in Seattle, WA

and Portland, OR.

April 2010

– Developed and led 1

‐ day training course on use of State of Oregon Guidance on Assessing

and Remediating Vapor Intrusion in Buildings

.

Vapor Intrusion Presentations

1998

– National UST

‐ LUST Conference, Albuquerque, NM

– Vapor Intrusion

– The Oregon Experience

2007

– Oregon Brownfields Conference, Salem OR, Primer on Vapor Intrusion

2009

– Northwest Environmental Conference, Portland, OR, Vapor Intrusion Continues to Mature: Legal, Regulatory and Technical Updates

2010

– EPA, Region 10 All States Meeting ‐ Assessing and Remediating Vapor Intrusion in Buildings

2011

– Northwest Environmental Business Conference, Portland, OR, Vapor Intrusion

‐ Evaluating the Marginal Cases