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Hill Air Force Base Restoration Advisory Board

Meeting Minutes

January 29, 2015

Members Present:

Organization: Members Present:

Organization:

Darrin Wray Hill AFB RAB AF Co‐Chair Clint Holm Layton Community At‐Large

Jan Ukena South Weber Community At‐Large

Stephen Jackson Layton City

Loren Allen Davis County Health Department

Tim Lane Roy Community At‐Large

Robert Becker Sierra Club Mike Petersen Clinton City

Travis Bonsteel Clinton Community Vern Phipps Clearfield Community At‐Large

Summer Day Weber‐Morgan Health Department

Ivan Ray Davis & Weber Canal Company

Buck Ekstrom Clearfield City Sandra Bourgeois Environmental Protection Agency

Bambi Gibson Sunset Community At‐Large

Muhammad Slam Environmental Protection Agency

Randy Hilton South Weber City

Members Absent:

Organization:

Jason Bowers Hill AFB Community Brett Nelson Central Weber Sewer District

Shawn Douglas Riverdale City Scott Paxman Weber Water Basin

Stan Hadden Riverdale City Rich Sirken Weber State University

Jeff MacFarlane North Davis Sewer District

Ed Sorensen Roy City

Peter Matson Layton City Clifton Specht North Davis Sewer District

Joe Maylin Sunset City Brian Wesoloski Riverdale Community

Brad Nelson Weber Water Basin Scott Zigich Davis County School District

Other Attendees:

Organization:

Jarrod Case Hill AFB Kalem Sessions AEEC

Shannon Smith Hill AFB Sandy Staigerwald

EA Engineering

Mark Roginske Hill AFB Randy Gates CH2M HILL

Shanna Clark AFCEC Ann Dziechciarz CH2M HILL

Shannon Garcia AFCEC Loren Lund CH2M HILL

Ron Lester AFCEC Jeremy Cox CH2M HILL

Kathleen Bradley AFCEC Corey Schwabenlander

CH2M HILL

Seth Smith AFCEC Andrew Castor CH2M HILL

Connie Richman Visitor Lorraine Jameson CH2M HILL

Casey Hill Visitor Brent Poll South Weber Coalition

Barbara Fisher Hill Public Affairs

Handouts Distributed at Meeting: Handouts: Agenda (attachment 1) Operable Unit 10 Proposed Plan (attachment 2) Operable Unit 4 Revised Proposed Plan (attachment 3) Indoor Air Program: Path to Final Remedy (attachment 4) Agenda Item #1. Welcome Mr. Darrin Wray, RAB Air Force Co-Chair called the meeting to order and welcomed RAB members in attendance. Ms. Barbara Fisher introduced herself and asked speakers to identify themselves to help in production of notes for the minutes. Agenda Item #2. RAB Business Mr. Jarrod Case said that work is still underway to get a support contract in place. Hopes are that a new support contract will be in place in spring 2015. Mr. Case said the annual mailing to stakeholders seeking their participation in the indoor air monitoring program will not take place this year. The Air Force will continue evaluation of the effort and mailing of the flyers may resume next year. The Air Force has continued to be in contact with stakeholders interested in the indoor air program and sampling is underway at some residences. Agenda Item #3. Operable Unit 10 (OU10) Proposed Plan Mr. Jeremy Cox provided an update on the OU10 Proposed Plan (attachment 2). Mr. Cox described the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) process and informed RAB members that the Remedial Investigation and Feasibility Study were completed in 2009 and the Feasibility Study Supplement was completed in 2014. The Air Force is now at the Proposed Plan and public comment period of the process. Completion of the Record of Decision is anticipated for 2015. Mr. Cox said the selected remedy will achieve the following Remedial Action Objectives:

Prevent direct exposure to contaminated groundwater Prevent unacceptable human health risks posed by the potential future inhalation of contaminant vapors in

on-base indoor air (current risks in indoor air are addressed by OU 15) Prevent further horizontal and vertical plume migration Restore groundwater to its expected beneficial use within a reasonable timeframe

Mr. Cox discussed the potential remedies that were evaluated for the tetrachloroethene (PCE) Plume, deep trichloroethene (TCE) Plume and shallow TCE plume in the Proposed Plan and described the following preferred alternatives: PCE Plume

The preferred alternative for the PCE Plume is Alternative 6: In situ treatment, monitored natural attenuation (MNA), and institutional controls (ICs). Mr. Cox explained that alternative 6 consists of targeted in situ (in place, subsurface) treatment in addition to monitored natural attenuation and institutional controls. The targeted treatment

consists of injecting a carbon source, such as emulsified vegetable oil, into the groundwater through injection wells. This treatment would occur in areas of high PCE concentrations to accelerate the cleanup of groundwater. Natural attenuation of the groundwater contaminants outside of the treatment areas would continue to be monitored and the ICs would remain in place until remedial goals are achieved.

Mr. Cox said the $1.6 million cost of this alternative is less than other alternatives, and the estimated time to cleanup also is less that other alternatives at 32 years.

Shallow TCE Plume

The preferred alternative for the Shallow TCE Plume is Alternative 4: in situ treatment, monitored natural attenuation and Institutional Controls. Mr. Cox said Alternative 4 consists of targeted in situ (subsurface) treatment in areas of high TCE concentrations, plus MNA and ICs. The targeted treatment consists of injecting a carbon source into the groundwater. The treatment would occur in the area of the highest TCE concentrations to accelerate the remediation of groundwater. Natural attenuation of the groundwater contaminants outside the treatment area would continue to be monitored and the ICs would remain in place until remedial goals are achieved.

This alternative would cost $2.3 million, which is less than other alternatives and take about 51 years to complete. The time to complete cleanup is less than other alternatives.

Deep TCE Plume

Alternative 2: Monitored natural attenuation and institutional controls is the preferred alternative to address contamination from the deep TCE plume. Alternative 2 includes maintaining the existing ICs in place while monitoring the ongoing natural attenuation of the groundwater contaminants. The ICs would remain in place until remedial goals are achieved.

The cost of $2.8 million is less than other alternatives. The estimated 67 years it will take to achieve cleanup is similar to the other alternatives.

Mr. Ivan Ray asked what is the goal to be achieved for beneficial use and would it be in parts per million? Mr. Cox said the contaminant levels in groundwater will need to be below EPA’s maximum contaminant levels (MCLs) and be safe to drink. Mr. Ray asked for a definition of potentiometric surface. Mr. Cox defined it as the height to which water rises in a well. Mr. Ray asked if there are any drinking water wells present in the area? Mr. Cox said that a Clearfield city well is present. Mr. Ray asked if groundwater can travel up and down the well casing. Mr. Cox said that drinking water wells are screened below the contaminated interval and the casings are grouted to prevent movement of groundwater. Mr. Stan Haddon inquired about an aboveground dumpsite (historical pond) located near the West Gate that may have contributed to OU10 contamination. Mr. Case said the area is named Bamberger Pond and it was investigated in the past as part of OU 5 and is not related to OU 10. Mr. Ray asked if contaminant concentrations are decreasing everywhere, or only at some sampling locations. Mr. Cox said that yes, concentrations are generally decreasing across OU 10. Mr. Ray asked what the cleanup goal is for OU 10 groundwater. Mr. Cox said the goal is to reach MCLs, which means the water would be safe to drink. Mr. Ray asked if the Permeable Reactive Barriers (PRBs) will require replacement at some point. Ms. Summer Day commented that the Roy City Permeable Reactive Barrier didn’t work all that well and if a different barrier material will be used for OU10. Mr. Cox said the PRBs would require replacement, but pointed out that the PRB alternative is not the preferred alternative for the OU10 Proposed Plan. A RAB member asked if in-place treatment described in the preferred alternative was meant to go on for the entire 51 years or if active in-place treatment would be shorter. Mr. Cox replied that active treatment is much shorter.

Mr. Ray asked if, based on the amount of degradation of PCE in the plume, there is a prediction about how long it will take to reach the cleanup goal. Mr. Cox said the process will be ongoing and take an estimated 32 years. Mr. Ray and Mr. Tim Lane asked why it would take 32 years for the plumes to naturally attenuate when historic data show the current concentrations have decreased so much after less than 20 years, if the modeling accounted for all potential attenuation mechanisms, and if the timeframe to reach MALs might be less than estimated. Mr. Lane asked what is happening now to account for the degradation and asked if it will take 32 years to reach the cleanup goal. Mr. Cox pointed out that when source concentrations are high, levels reduce rapidly. As contaminants become increasingly diluted in the plume, the process slows. Modeling did account for all attenuation mechanisms and the timeframes for completion of remediation are estimates with a degree of uncertainty associated with them, so that timeframes potentially could be shorter. Mr. Clint Holm asked how the treatability study is progressing. Mr. Cox said that the study is showing degradation of PCE where the substrate was injected. Mr. Ray, Mr. Travis Bonsteel and Mr. Lane asked for an explanation of what is in place that is reducing contaminants in the PCE plume, such as trees. Mr. Cox said that phytoremediation, a component of natural attenuation, is taking place, but it has limitations. Phytoremediation can only take place when tree roots reach the groundwater. He explained that a number of factors contribute to natural attenuation and all work together. Agenda Item #4. OU4 Data Gap Investigation Update/Revised Proposed Plan Mr. Andrew Castor discussed the data gap investigation and Revised Proposed Plan for OU4 (attachment 3). OU4 consists of three source areas: Capped Landfill 1, Uncapped Landfill 1 and Landfill 2. He provided RAB members with an overview and background about the site that included information about long-term groundwater monitoring, details of the 1994 Record of Decision and an aerial photograph showing details of the existing remedy. Mr. Castor said that TCE in the primary contaminant of concern for OU4 and groundwater monitoring has been ongoing since 1986. During this time, the TCE plume has not significantly expanded since it was originally delineated and TCE concentrations have remained consistent with the exception of monitoring well U4-047. This well is located immediately downgradient of the capped portion of Landfill 1. TCE concentrations began increasing in 2002 and have remained relatively constant for the past several years – greater than 10,000 ppb. The following are the components of the existing remedy:

Low-permeability cap installed at Landfill 1 Passive groundwater collection system using horizontal drains (HDUS) that discharges to sanitary sewer Monitoring of groundwater, springs, and seeps Institutional controls

‐ Fencing and signs to limit access to landfill cap ‐ Air Force construction and excavation restrictions and permits ‐ Restriction of domestic use of shallow groundwater within OU 4

Residential indoor air is addressed by OU15 Ms. Day asked when the drains were installed. Mr. Castor said 1996. Mr. Ray asked if the water from the drains is monitored, and Mr. Castor said it is. Mr. Ray asked where the water extracted by the HDUS goes. Mr. Castor said the water is monitored, and the Air Force has a permit to send it to the treatment plant for ultimate discharge to the sanitary sewer system. Mr. Castor described the performance of the existing remedy and explained that a Five-Year Review in 2013 found that the current remedy is remains protective in the short-term, but is not functioning as intended. The proposed

expanded remedy was developed in response to the results of the 2013 Five-Year Review. The remedial action objectives for the revised remedy are:

Meet groundwater regulatory requirements Limit human health risks due to accidental ingestion, dermal contact, or inhalation of vapors Prevent further degradation of groundwater quality Eliminate the source(s) of groundwater contamination either through removal or source control Prevent migration of contaminated soil gas into residences – OU 15

The proposed expanded remedy consists of maintaining all components of the existing remedy and implementation of the following additions to address source areas and treat TCE-contaminated groundwater. Source Areas Install a bioreactor within capped portion of Landfill 1

‐ Upgradient of monitoring well U4-047 ‐ Excavate and dispose of source material ‐ Backfill with mulch, gravel, and emulsified vegetable oil (EVO) ‐ Biologically treat TCE-contaminated soil and groundwater

Uncapped Landfill 1 and Landfill 2 ‐ Targeted shallow excavation of TCE-contaminated soil ‐ Installation of soil vapor extraction (SVE) systems to treat remaining TCE-contaminated soil

Non-Source Area Install enhanced reductive dechlorination biobarriers

‐ Rows of injection points within core of eastern plume lobe ‐ Emulsified vegetable oil (EVO) injections ‐ Biologically treat TCE-contaminated groundwater

Mr. Ray asked how thick the biobarriers would be and Mr. Castor said they are about 15 feet thick. Ms. Day asked what types of soils are present in the area. Mr. Castor said primarily clays and gravels. Mr. Hadden asked if ground penetrating radar was considered to help find the source of contamination. Mr. Castor said some below-ground-surface imaging was used. Mr. Lane asked if it would be better to just dig up the landfill - uncap it, excavate it and get the source material out. Mr. Castor said the Proposed Expanded Remedy is a compromise to address a portion of the landfill and get rid of the hot spot. Ms. Day said she applauded the more aggressive approach to addressing contamination issues at OU4. Mr. Castor said the proposed expanded remedy meets seven of the nine evaluation criteria. Tentative agreement will be obtained from the EPA and UDEQ before the public comment period. Public comments will be accepted during the public comment period. The proposed expanded remedy reduces the amount of time to address groundwater contamination at OU4 from an indefinite timeframe to 60 years. The cost would increase from $6,255,000 to $7,488,000. Mr. Ray asked what potential federal budget cuts might have on implementation of the remedy. Mr. Castor said that the largest part of the costs occur early in the implementation process. Long-term monitoring, which is less costly, occurs later in the process. The public comment period will be scheduled following EPA and UDEQ approval of the Revised Proposed Plan, possibly in spring 2015. The Air Force will prepare the Record of Decision Amendment following the public comments and expects to submit the document to EPA and UDEQ in fall 2015.

Mr. Randy Hilton asked how long construction will take. Mr. Castor replied about six months. Mr. Bonsteel asked what other options were considered. Mr. Castor explained that because this is a post-ROD change, there is no requirement to evaluate a number of options. The data gap evaluation determined that the Proposed Expanded Remedy would meet RAOs and address contamination from source areas and affected groundwater. Agenda Item #3. Vapor Intrusion Update Dr. Shanna Clark updated the presentation from the July 2014 RAB meeting (see attachment 4). Key components of the update focused on progress towards the final vapor intrusion remedy at Hill AFB, new toxicity data for TCE, new efforts to address uncertainty when presenting risk data to stakeholders, and new variability research updates and how the new information affects the Air Force’s Indoor Air Program at Hill AFB moving forward. Progress Towards the Final Remedy Dr. Clark said the CERCLA process includes three fundamental stages: (1) Remedial Investigation (RI) - Data Collection; (2) Feasibility Study (FS) – Remedy Consideration; and (3) Record of Decision (ROD) – Remedy Selection. Stage 1 has been ongoing since the early 2000s and is nearing completion– nearly 2,000 homes have been sampled as part of the Indoor Air Program (IAP). Stage 2 is currently underway – using the data collected in Stage 1, the Air Force is beginning to consider the shutdown criteria for vapor removal systems (VRSs) and updating the Mitigation Action Level (MAL). Dr. Clark said the last step in Stage 1 is the risk assessment, which will be included in the RI Report. In basic terms, risk is a function of how much of a compound is ingested multiplied by how toxic that compound is. The amount taken in is measured through the air data collected through the years and basic exposure estimates. The toxicity of a substance is derived from scientific literature, which generally uses estimates from animal studies.

Dr. Clark said uncertainty accompanies each step. The data collection, exposure assessment, toxicity assessment steps, as well as the analysis and final risk characterization and risk management steps, all include uncertainty. There is also uncertainty and variability in the toxicity value that goes into establishing the interim MAL and the preemptive mitigation done using the interim MAL.

Each remedial alternative presented for a final remedy in the Feasibility Study is evaluated against two threshold criteria, five balancing criteria, and three modifying criteria, which are considered after the Proposed Plan is released. Dr. Clark said if the remedial alternative does not meet the threshold criteria, which are protection of human health and the environment and compliance with regulatory requirements, she said then it is not considered further (unless a waiver applies). If the remedial alternative meets the threshold criteria, it is further screened against the five balancing criteria (long- and short-term effectiveness, reduction of toxicity, mobility and volume through treatment, implementability, and cost) in the detailed analysis in the FS.

Toxicity Updates To date, the concentration of these chemicals detected in indoor air has been studied for years and is well characterized. Chemicals detected in the Indoor Air Program include TCE, cis-1,2-dichloroethene (cis-DCE) and trans-1,2-dichloroethene (trans-DCE), and PCE. Of those, TCE is most often detected and PCE and trans-DCE are often from interior sources and not VI. Regardless, a proactive, conservative, interim MAL was developed for each of these compounds as a screening-level way to assess health risk. As we proceed to a Record of Decision, now we are moving from interim MAL through the Feasibility Study steps.

The EPA is re-evaluating toxicity for both cis-DCE and trans-DCE; therefore, the mitigation action level is likely to change in 2015-2016. Current toxicity data for TCE from three sources are relatively similar: ATSDR Minimal Risk Level: 0.4 parts per billion by volume (ppbv); EPA Reference Concentration: 0.37 ppbv; Hill AFB interim MAL: 0.38 ppbv. However, there are different measures of uncertainty in those risk levels. First, they are “lifetime” screening levels; slightly exceeding them does not mean effects will happen (a realistic exposure pattern is not indoors 24/7 for a lifetime). Second, there is a 90-times safety factor built into the MAL. Third, an ARA peer-review panel determined that toxicologists cannot tell the difference between 0.38 ppbv and 3.7 ppbv TCE: thus, up to 10-times the MAL is within the range of toxicity value uncertainty (3.8 ppbv).

Previous RAB meetings have discussed the variability of TCE levels measured in the Arizona State University research house in Layton. While the home did show variability, the variability was within the range of TCE toxicity variability (i.e., TCE concentrations did not exceed 3.8 ppbv). In 2014, there was one home with a detection above 3.8 (approximately 5 ppbv). Because of the 90x safety factor, actual health effects are not expected until much higher concentrations (i.e., 33 ppbv) which has not been seen in the research house or ever in the 2,000 homes sampled as part of Hill AFB’s Indoor Air Program. Further, she said, recent findings at the research house have shown it has some unique features which may be adding to the variability. Conclusions

Dr. Cark said the stakeholders can confidently optimize the program. It is not necessary to recruit more homes to participate in the Indoor Air Program once the rest of the CERCLA risk process steps are considered. Dr. Cark said it is also not necessary to sample more frequently to characterize data variability, based on what has been learned to date.

The likelihood or probability of “missing a detection” is not a critical decision point. Dr. Clark said, because of the confidence in the data from 2,000 homes already measured and the existing data set. She said it is far less likely that the Air Force will “miss” a TCE detection over the hazard range and certainly this data set has not seen any indoor air TCE at concentrations approaching a human equivalent concentration for noncancer effects. Ultimately a regulatory risk management recommendation will be made after all stakeholders – EPA, State, AF, and residents – review submittals and weigh in.

A RAB member asked if the Air Force is loosening the toxicity standard based on that uncertainty. Dr. Clark said the Air Force has not loosened the standard. The Interim MAL was established to be conservative on an interim basis. The MAL has changed through time as new toxicity values have come out. The Air Force is not proposing to change the current Interim MAL right now. What the Air Force wants to do is be able to convey to the residents that there is some uncertainty in that level, and use that discussion to figure out how often the residence is sampled and whether or not the resident and risk managers are comfortable turning off existing systems.

A RAB member asked if residents still want to be sampled will they be sampled? Dr. Clark said yes, that is still part of the program. A RAB member asked what the exact title of the study was and in what journal it was published. Dr. Clark said a weblink to the study is in the PowerPoint presentation/handout each RAB member was provided. She said the White Paper, peer review slide shows, comments, etc. can all be found on the website. A RAB member asked if the actual toxicity data is on the website. Dr. Clark said the data is from individual studies that EPA/IRIS evaluated. They are available on the IRIS website, but they’re also in the bibliography on the ARA website. A RAB member asked if the ten-fold uncertainty that was discussed is specific to TCE or normal practice. Dr. Clark said it’s specific to TCE, but there are uncertainties with other compounds. A RAB member asked while there is uncertainty, it is a known uncertainty, right? Dr. Clark explained that there’s a known animal response that is converted to an estimated human response and then the uncertainty factor, which is a safety factor, is applied. A RAB member said that it’s more than a safety factor because people are exposed to other chemicals and there are sensitive sub-populations. Dr. Clark said that in this case, the safety factor includes sensitive subpopulation, such as a developing fetus. Mr. Travis Bonsteel said last year, there were only four homes with detections above the MAL. What changed? Dr. Clark said this was just last years’ sampling. There are other homes that have VRS systems. It would be good for the next meeting to create some figures showing where VRS systems are located around the base.

Mr. Clint Holm asked about the slides with the green and purple lines where Dr. Clark said “we are just as safe at this line as we are at that line.” Mr. Holm said isn’t it more correct to say that it’s just unquantifiable? Dr. Clark said that was correct. A toxicologist could not tell you the difference between the risk at the green line and the risk at the purple line which can be interpreted as “just as safe.” The EPA and UDEQ have not weighed in on how they’d like to see this worded. A RAB member asked if communication will change with residents. Dr. Clark said that now the communication can be improved and the Air Force can discuss the number of samples, results, trends, etc. and compare those to the uncertainty range. Mr. Robert Becker said if the peer-reviewed study is a meta-analyses (combining many studies). Dr. Clark said the ARA study evaluated uncertainty around each of multiple peer-reviewed individual studies. Of multiple studies, there has been one “positive” study (study with health effects), the rest have shown no health effects. Agenda Item #4. Public Comment Opportunity Mr. Brent Poll discussed a recent federal district court case Waverley View Investors LLC v. U.S. that he said found that addressing environmental hazards at an Army site was discretionary for the Army. They could clean it up, or not. It is their choice. Mr. Poll said this case could support lack of funding as a reason for a government agency to refuse to address environmental hazards. He said this is an important issue because it could allow government agencies to decide to stop work on environmental cleanups. He also stated that the Pentagon has the discretion to withhold information requested through the Freedom of Information Act which limits transparency for stakeholders. The RAB and the coalition works only if there is transparency. He also said that to have a remedy provide true protectiveness, there must be an accompanying compliance program when institutional controls are a component of a remedy. He said because ICs, such as vapor intrusion systems, are almost exclusively voluntary, there should be a way to enforce them. Agenda Item #5. Agenda Items for April 30, 2015 Meeting Ms. Fisher asked RAB members for agenda items for the April 30, 2015, meeting. None were forthcoming. She will contact RAB members again before the meeting. Agenda Item #6. Adjournment Ms. Fisher adjourned the meeting at 8:55 p.m.

Hill AFB Restoration Advisory Board

Meeting 6:30 p.m.

January, 29 2015

Sunset City Building (Sunset Room)

200 West 1300 North Sunset, Utah

RAB Meeting Agenda

6:30 – 6:35 Welcome ................................................... Darrin Wray, RAB Community Co-Chair 6:35 – 6:50 RAB Business ............................................................. , Barbara Fisher/Mark Loucks

Contracting Issues – Mark Loucks, Hill AFB Update on Yearly Mailers – Jarrod Case, Hill AFB

6:50 – 7:10 OU10 Proposed Plan 15 minutes Presentation ........................................................... Jeremy Cox, Hill PBR Contractor 5 minutes RAB Questions and Discussion 7:10 – 7:40 OU4 Data Gap Investigation Update/Revise Proposed Plan 20 minutes Presentation .......................................................... Andy Caster, Hill PBR Contractor 10 minutes RAB Questions and Discussion 7:40-7:50 Break (no break-out sessions) 7:50 – 8:15 Vapor Intrusion Updates 15 minutes Presentation ........................................................... Dr. Shanna Clark, AFCEC/CZTE 10 minutes RAB Questions and Discussion 8:15 – 8:20 Public Comment Opportunity 8:20 – 8:25 Agenda Items for April 30, 2015 Meeting 8:25 Adjourn

Air Force Civil Engineer CenterI n t e g r i t y - S e r v i c e - E x c e l l e n c e

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January 2015

EA Engineering, Science, and Technology, Inc.

Operable Unit 10 Proposed Plan

I n t e g r i t y - S e r v i c e - E x c e l l e n c e

Where is OU 10 in the Regulatory Process?

2


Outline

Operable Unit (OU) 10 Overview/Background

Remedial Action Objectives

Potential Remedies

Comparison of Alternatives

Preferred Remedial Alternatives

Schedule

3


Hill AFB – OU 10 Location

4


Conceptual Site Model


TCE and PCE Plumes


Groundwater Contaminants

Maximum Concentration(ppb)

Remedial Goals (ppb)

Historical (1990s to 2012)

Current(2013)

Upper Zone (Shallow Plumes)Trichloroethene (TCE) 489 110 5

Tetrachloroethene (PCE) 722 88 5

cis-1,2-Dichloroethene (cis-1,2-DCE)

65 33 70

Lower Zone (Deep Plume)TCE 750 310 5cis-1,2-DCE 170 140 70


Remedial Action Objectives

Prevent direct exposure to contaminated groundwater

Prevent unacceptable human health risks posed by the potential future inhalation of contaminant vapors in on-Base indoor air (current risks in indoor air are addressed by OU 15)

Prevent further horizontal and vertical plume migration

Restore groundwater to its expected beneficial use within a reasonable timeframe


Potential Remedies (Slide 1 of 4)

No Action

Monitored Natural Attenuation (MNA) and Institutional Controls (ICs) – monitoring and controls to limit public access

(All other remedies include MNA and ICs as integral parts of each alternative)



Containment (Permeable Reactive Barriers)



Groundwater Extraction/Treatment and Discharge



In Place Treatment (In Situ Chemical Oxidation, Enhanced Bioremediation, Phytoremediation)


Alternative Comparison/

Preferred Alternative

PCEPlume


PCE Plume Rationale for Selection

Alternative 1 (No Action) – Not protective of human health due to lack of monitoring & potential for exposure

Alternatives 2, 3, 4, & 5 – All have moderately effective long-term permanence and reduction of toxicity, mobility, or volume. All have remediation timeframes of 45 to 65 years.

Preferred Alternative: Alternative 6 (In Place Treatment, MNA, & ICs) – good long-term permanence, reduction of toxicity, mobility, or volume. Remediation timeframe is 32 years. More cost-effective.




Shallow TCE Plume


Shallow Plume TCE Rationale For Selection

Alternative 1 (No Action) – Not protective of human health due to lack of monitoring and potential for exposure

Alternatives 2 & 3 – Both have moderately effective long-term permanence and reduction of toxicity, mobility, or volume. Both have remediation timeframes of 64 to 74 years.

Preferred Alternative: Alternative 4 (In Place Treatment, MNA, & ICs) – good long-term permanence, reduction of toxicity, mobility, and volume. Remediation timeframe is reduced to 51 years. More cost-effective.




Deep TCE Plume


Deep TCE Plume Rationale For Selection

Alternative 1 (No Action) – Not protective of human health due to lack of monitoring and potential for exposure

Preferred Alternative: Alternative 2 (MNA & ICs) –The remedial investigation and feasibility studies indicate natural degradation of contaminants in the deep plume

Alternatives 3, 4, & 5 – Active treatments will not reduce the remedial timeframe as compared to natural attenuation, and are more costly and more intrusive to the community as compared to Alternative 2.


OU 10 Preferred Alternatives

PCE and Shallow TCE Plumes

–Targeted In Place Treatment,

MNA, and ICs

Deep TCE – MNA and ICs


OU 10 Treatment Areas

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 10

Treatability Study began on-Base in July 2014 to evaluate effectiveness of Enhanced Bioremediation

Public comment period and public meeting will be scheduled following EPA/UDEQ approval of Proposed Plan – Late Winter / Spring 2015

Schedule


Questions?

Air Force Civil Engineer CenterI n t e g r i t y - S e r v i c e - E x c e l l e n c e

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EA Engineering, Science, and Technology, Inc.

Operable Unit 4 Revised

Proposed Plan


CERCLA Process at OU 4

The CERCLA process is working

Monitoring and 5-Year Review Recommendations Additional Investigations Identification of 3 TCE source areas

Proposing expanded remedy through Revised Proposed Plan


Hill AFB – OU 4 Location


OU 4 Overview / Background

Source Areas

Capped Landfill 1

Monitoring has indicated that TCE concentrations in groundwater have increased to >10,000 ppb immediately downgradient of Landfill 1 cap - ongoing source of TCE contamination to groundwater

Uncapped Landfill 1

200- by 200-foot area of TCE contamination in soil (0 to 35 ft bgs), highest concentration 390,000 ppb (5 ft bgs)

Landfill 2

100- by 100-foot area of TCE contamination in soil (0 to 20 ft bgs), highest concentration 300,000 ppb (15 ft bgs)


OU 4 Site Map


OU 4 Overview / Background

Long-Term Groundwater Monitoring

TCE is primary Contaminant of Concern

Ongoing since 1986

TCE plume has not significantly expanded since original delineation

Overall concentrations have remained fairly constant

Exception: Monitoring Well U4-047

Located immediately downgradient of capped portion of Landfill 1

Concentrations began increasing in 2002 and have remained relatively constant for the past several years (>10,000 ppb)

Indicates a continuing source of TCE contamination to groundwater within capped portion of Landfill 1


OU 4 Existing Remedy

1994 Record of Decision (ROD)

Low-permeability cap installed at Landfill 1

Passive groundwater collection system using horizontal drains (HDUS) that discharges to sanitary sewer

Monitoring of groundwater, springs, and seeps

Institutional controls

Fencing and signs to limit access to landfill cap

USAF construction and excavation restrictions and permits

Restriction of domestic use of shallow groundwater within OU 4

Residential indoor air addressed by OU 15


OU 4 Existing Remedy


OU 4 Remedial Action Objectives

Meet groundwater regulatory requirements

Limit human health risks due to accidental ingestion, dermal contact, or inhalation of vapors

Prevent further degradation of groundwater quality

Eliminate the source(s) of groundwater contamination either through removal or source control

Prevent migration of contaminated soil gas into residences – OU 15


Existing Remedy Performance

2013 Five-Year Review Current remedy is not functioning as intended but remains protective in the short-

term

Low-permeability Landfill 1 cap Likely limits infiltration of surface water

Increase in TCE concentrations in groundwater downgradient of Landfill 1

Landfill 1 contents - Ongoing source of TCE contamination - Indefinite remedial timeframe

HDUS Extracted 35,000,000 gallons of groundwater and 224 pounds of TCE since 1996

Removed 3.3 pounds of TCE in 2014

Compared to calculated mass of 1,100 pounds of TCE in groundwater

Uncapped Landfill 1 and Landfill 2 also identified as on-going TCE source areas


OU 4 Proposed Expanded Remedy

Source Areas

Install Bioreactor within Capped Portion of Landfill 1

Upgradient of Monitoring Well U4-047

Excavate and dispose of source material

Backfill with mulch, gravel, and emulsified vegetable oil (EVO)

Biologically treat TCE-contaminated soil and groundwater

Uncapped Landfill 1 and Landfill 2

Targeted shallow excavation of TCE-contaminated soil

Installation of soil vapor extraction (SVE) systems to treat remaining TCE-contaminated soil



Non-Source Area

Install enhanced reductive dechlorination biobarriers

Rows of injection points within core of eastern plume lobe

EVO injections

Biologically treat TCE-contaminated groundwater

Maintain All Components of Existing Remedy

Landfill 1 cap

HDUS

Monitoring of water quality of groundwater, springs, and seeps


Evaluation of Proposed Expanded Remedy

Overall Protectiveness Protective of Human Health and the Environment

Maintains ICs on soil and groundwater; long-term monitoring

Addresses on-going sources areas and accelerates remedial timeframe

Compliance with State and Federal Regulations Proposed expanded remedy can comply will all state and federal

regulations

Implementability Proposed expanded remedy is technically and administratively

implementable

Technologies successfully applied at several U.S Department of Defense sites



Long-Term Effectiveness and Permanence More effective than existing remedy – source control

Permanent solution by removing, treating, and capping source area soils

Without continuing source, ERD biobarriers will accelerate remedial timeframe

Reduction of Toxicity, Mobility, or Volume Faster and more complete reduction of TMV through removal and

treatment of TCE in on-going source areas and groundwater

Short-Term Effectiveness Transportation of construction equipment and contaminated soil for

disposal can be conducted with minimal impacts to community



Cost

Regulatory Acceptance Tentative agreement will be obtained from EPA and UDEQ prior to public

comment period, subject to change based on public comments

Community Acceptance Public comments will be evaluated to assess the community’s

acceptance

Existing RemedyProposed Expanded

Remedy

Remedial Time Frame

Indefinite 60 years

Present ValueTotal Cost

$6,255,000 $7,488,000


Public comment period will be scheduled following EPA/UDEQ approval of Revised Proposed Plan –Spring 2015

Record of Decision Amendment to be prepared by Air Force following public comment period; expected to be submitted to the EPA/UDEQ – Fall 2015

Schedule


Questions?


Indoor AirProgram: Path to

Final Remedy

1

Dr. Shanna Clark, ToxicologistAFCEC Technical Support Division

29 January 2015


Roadmap

• This updates slide deck shown 30 July 2014

• Progress towards final remedy via risk

assessment and CERCLA process

• New toxicity data updates

• New variability research updates

• What this means for 2015-2016 planning


Focusing In On 2015-2016

3

CERCLA Superfund PROCESSRI/DATA COLLECTION FS: REMEDY ROD: REMEDY

STAGE (AWARENESS) CONSIDERATION SELECTION

Update MAL, add shutdown criteria, only VI

2004-2014 2015-2016

Final VI Remedy

RI >2,000 homes

PreemptiveVRS atInterim

MAL even if not VI

TIME


Process

• Progress towards final remedy via risk assessment and CERCLA process

• CERCLA funds cannot clean up indoor air below background: only VI-related chemicals

• For indoor air, this means if an interior source is found and VI is not occurring, a CERCLA remedy is not required


Risk Assessment Steps

RISK = HOW MUCH WE TAKE IN x HOW TOXIC IT COULD BE

Air Data:

Concentration of the VI-relatedchemical in indoor air

Exposure Data:Estimate exposures

(how much contact time, how often, how long)

+

Toxicity Data:

derived from the scientific

literature

generally estimated from animal studies(little human data)

I n t e g r i t y - S e r v i c e - E x c e l l e n c e6

Role of Risk Characterization

Risk characterization is the primary vehicle for communicating health risk assessment findings.

Many risk characterizations have relied primarily on mathematical estimates of risk to communicate risk assessment findings, often conveying an unwarranted sense of precision while failing to convey the range of scientific opinion.

Presidential Commission on Risk Assessment and Risk Management (1997)

I n t e g r i t y - S e r v i c e - E x c e l l e n c e7

Role of Risk Characterization (cont’d)

Risk characterization is not only about science — it is also about making clear that science doesn’t tell us certain things and that policy choices must be made.

Transparency: communicate assessment strengths & weaknesses.

Today’s discussion is a preview that reflects the Air Force proposal for risk communication: RAB and public and EPA and State will all see

written documents with these concepts in the future and will be able to comment on those CERCLA submittals.

EPA Risk Characterization Handbook


Nine Criteria for Evaluating Alternatives2 Threshold 5 Balancing 2 Modifying

Overall protectionof human health

and the environment

Communityacceptance

Regulatoryacceptance

Yes

No

Compliance with applicable or relevant and appropriate

requirements

Reduction of toxicity, mobility, or volume through treatment

Short-term effectiveness

Cost

Implementability

Long-term effectiveness and permanence

8


Roadmap








Chemicals Detected

10

To date, the concentration of these chemicals detected in indoor air has been studied for years and is well characterized. A proactive, conservative, interim MAL was a screening-level way to assess health risk. As we proceed to a Record of Decision, now we are moving from interim MAL through Feasibility Study steps.

What We Know Based on 2004-2014 Progressive Lessons Learned

…Often not VI

………Rarely, if ever, due to VI


DCE Toxicity UpdateBreakdown products of PCE -> TCE -> DCEs

• cis-DCE and trans-DCE are both being re-evaluated for toxicity: recall trans not likely from VI

• EPA does not recommend a current nationwide toxicity value or regional screening level for DCEs: EPA removed 2014 toxicity factors from databases

• Therefore, MAL is likely to change in 2015-2016

• Both cis-DCE and trans-DCE will be covered as toxicity value updates in next Five-Year Review (5YR)


TCE Toxicity UpdateTCE (most often detected)• MRL = Minimal Risk Level (ATSDR 2014)• RfC = Reference Concentration (EPA 2014):

“An estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime… with uncertainty factorsgenerally applied to reflect limitations of the data used.”

ATSDR MRL 0.4 ppbv

Approximately same as EPA RfC

2 µg/m3 = 0.37 ppbv

Hill Interim MAL = 0.38 ppbv (rounding and

significant figures)


NAS (2014) & IRIS Process

“Finding: EPA could improve documentation and presentation of dose-response information.

Recommendation: EPA should clearly present two dose-response estimates: a central estimate … and a lower-bound estimate for a point of departure from which a toxicity value is derived.” [emphasis added]

National Academies of Science (NAS) Review of EPA's Integrated Risk Information System (IRIS) Process

13


What Does TCE > MAL mean?• ATSDR Minimal Risk Level (MRL)• All approximate lifetime “safe” levels:

RfC ≈ MRL

• While preemptively the Hill team selected these screening levels as the interim Mitigation Action Level (MAL) for TCE, slightly exceeding them does not mean effects will happen.

• MAL = EPA Reference Concentration, a lifetime screening level: MAL X 90 = HEC99 effects level


From July (2014) RAB Slides

2 2

0

20

40

60

80

100

120

140

160

Clearfield Clinton Layton Riverdale Roy South Weber Sunset

Homes Sampled

Detections

TCE>MAL (#)

Updated (2015) RAB Slides


Uncertainty in Risk Assessment

16

• “Uncertainty lies mainly above the RfC… This is because RfCs are based on lower bounds on points of departure and uncertainty factors are known to be protective” [safety factors].

• Uncertainty in toxicity assessment can be used to explain what a hazard “range” might look like: to overcome data gaps, we add safety factors

• ARA (2013, 2014) not endorsed by EPA or the State: simply part of peer-reviewed scientific body of literature for transparency in risk communicationAlliance for Risk Assessment (ARA 2013). Trichloroethylene (TCE) Risk Assessment Guidance for Contaminated Sites. http://www.allianceforrisk.org/Projects/ARA_TCE_Risk_Assessment_Guidance_for_Contaminated_Sites_2013.pdf


Last Winter 2013-2014 Details

17

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Green line shows the 24-hr, 30-year EPA Reference Concentration (selected as interim MAL) for TCE = 0.38 ppbv

HQ = 1.2

HQ = 0.9

HQ = 1.2 HQ =

0.7

HQ = 1.9: Awaiting owner’s risk management decision to proceed or cancel install of VRS.

HQ = 3.5. VRS Installed.

HQ = 0.8

HQ = 0.9

HQ = 1

HQ = 0.6

HQ = 1.5: VRS Installed

Purple line shows the range including uncertainty around the 24-hour, 30-year EPA Reference Concentration for TCE up to 3.7 ppbv:

Toxicology study imprecision exists in the space between the EPA RfC between the MAL (RSL) and 10X the RfC (3.7 ppbv; ARA 2013)We are just as safe at the purple

line as the green line given risk assessment uncertainty.


Overlay Tox Uncertainty

18

Consider and acknowledge MAL (green line) uncertainty (up from the MAL of 0.38 ppbv to 3.7 ppbv using ARA 2013 basis). So yes, there is temporal (seasonal/daily) variability, but overlaying what we do and don’t know about precise toxicity makes the TCE research house variability less important. Upcoming update regarding unique house structure that generated this variability!

Until > 3.7 ppbv, MAL uncertainty overcomes data uncertainty for a 24-hour continuous exposure

MAL 0.38 (below) to 3.7 ppbv


Where Effects Could Happen

19

0.0

5.0

10.0

15.0

20.0

25.0

30.0

TCE (ppbv)

Green line shows the interim MAL for TCE ~ 0.38 ppbv (approximately to EPA lifetime 24-hour RfC and ATSDR MRL)

Since safety factors of 10 x 3 x 3 are used on the Human Equivalent Concentration protecting the 99th percentile (HEC99), animal studies did not see an effect until 90X higher


Hazard Range for TCE NoncancerEffects: 2014 Peer Review

20


Roadmap








2014 SERDP/ESTCP Webinar

Initial study results from ASU indicated that vapor intrusion was highly variable: by 2014, closing valve on land drain cuts off much (if not all) indoor TCE

SERDP/ESTCPfunded two 2015projects to sort out preferentialpathway (land drain)and how prevalentthis design is

Affects mitigation


Land Drain Discovery


Conclusions

Take Home Message: Not all homes will behave like the ASU research house, especially if there’s no land drain at an individual house: The SERDP ESTCP webinar concluded: “We have established that the land drain definitely contributes to what

we see in the controlled pressure testing and probably has something to do with what is causing the spikes over time” [emphasis added]

Air Monitoring Program Implications: Not necessary to recruit more homes once the rest of the CERCLA risk process steps are considered:

Not necessary to sample more frequently to characterize data variability, in consideration of what we have learned today and to date

Ultimately a regulatory risk management recommendation will be made after all participants – EPA, State, AF, and residents – review submittals.


CERCLA Superfund PROCESSRI/DATA COLLECTION FS: REMEDY ROD:

Update MAL, add shutdown criteria, only VI

2004-2014 2015-2016

Final VI Remedy

RI >2,000 homes

PreemptiveVRS atInterim

MAL even if not VI

TIME

… Now confidently assess optimization to arrive at the proposed VI remedy for OU15.

Previously we stated we were not sure exactly how the research house data would affect the IA sampling program: Updated with today’s info!

How to Focus

5YR


Questions?

26


ReferencesARA (2013). Trichloroethylene (TCE) Risk Assessment Guidance for Contaminated Sites. http://www.allianceforrisk.org/Projects/ARA_TCE_Risk_Assessment_Guidance_for_Contaminated_Sites_2013.pdf.

ARA (2014). Peer Review Workshop of TCE Hazard Range and Uncertainty in the Reference Concentration. http://www.allianceforrisk.org/Workshop/WS8/DR8_Meeting_Report_and_Appendices.pdf.

EPA (2014). http://www.epa.gov/risk_assessment/glossary.htm#r last updated 4/28/14.

NAS (2014). Review of EPA's Integrated Risk Information System (IRIS) Process. Committee to Review the IRIS Process; Board on Environmental Studies and Toxicology; Division on Earth and Life Studies; National Research Council. The National Academies Press at http://www.nap.edu/catalog.php?record_id=18764.

SERDP/ESTCP (2014) Webinar: Lessons Learned from Monitoring a House Overlying a Dissolved Chlorinated Hydrocarbon Plume Under Natural and Controlled Depressurization Conditions. October 30. https://www.serdp-estcp.org/Tools-and-Training/Webinar-Series/10-30-2014.

27


Backup Slide Detail

28


Key Element Related to Threshold Criteria: Final Remediation Levels

Final remediation levels typically differ from RSLs: (regional screening levels were used first, and then preliminary remediation goals were developed early in the process)

often reflect different exposure factors (site-specific)

assure local background concentrations are addressed

may correspond to a different risk target (e.g., 10-5 vs. 10-6)

are documented in the ROD (the PRGs are not)

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