July_2014_Bi-Annual_Groundwater_Monitoring_Report.pdf

July 2014 Bi-Annual Groundwater Monitoring Report

Bitterroot Valley Sanitary Landfill Ravalli County, Montana

September 2014

Bi-Annual Report July 2014 Groundwater Monitoring

Bitterroot Valley Sanitary Landfill Ravalli County, Montana

Prepared for:

National Institutes of Health Division of Environmental Protection Building 13, Room 2W64 Bethesda, Maryland 20892

Prepared by:

SMART Consulting and Tetra Tech

2525 Palmer Street Suite 2 Missoula, Montana 59808

Tetra Tech Project No. 9732221C

September 2014

National Institutes of Health Bi-Annual Report, July 2014 Groundwater Monitoring, BVSL

SMART Consulting and Tetra Tech i September 2014

EXECUTIVE SUMMARY

In November 2000, the United States on behalf of the National Institutes of Health (NIH) and the State of Montana on behalf of the Montana Department of Environmental Quality (DEQ) entered into a Settlement Agreement regarding the Bitterroot Valley Sanitary Landfill (BVSL). The Settlement Agreement generally establishes the requirements for groundwater monitoring at BVSL. The full details of the groundwater monitoring required by the Settlement Agreement are contained in the groundwater monitoring plans which have been mutually agreed upon by the DEQ and the NIH. The previous groundwater monitoring plan (Amended Final Work Plan Groundwater Monitoring, Maxim 2002) guided groundwater monitoring between January 2003 and July 2013. The current groundwater monitoring plan (2014 Amendment to the December 2002 Amended Final Work Plan; Tetra Tech 2014b) is an amendment to the December 2002 Amended Final Work Plan and provides the basis for that monitoring in acknowledgement of the agreements between NIH and DEQ. The 2014 Work Plan supersedes all others. Specific details regarding the requirements of the Settlement Agreement are provided in the specific sections of the Work Plan.

The DEQ’s selected cleanup alternative for BVSL includes the design and construction of a community water supply system (CWSS), implementation of institutional controls, natural attenuation of groundwater contamination, and groundwater monitoring. NIH’s obligation under the Settlement Agreement ended with respect to the community water supply system with a force majeure event with the exception of groundwater monitoring. Institutional controls were created in the form of a controlled groundwater area established and administered through the Montana Department of Natural Resources and Conservation (DNRC). The current Work Plan focuses on the remaining NIH obligations for groundwater monitoring. Those obligations are:

Tracking temporal and spatial trends in groundwater flow and quality.

Evaluating the effects of NIH's 1993-94 soil removal action and effects of NIH’s Phase IIA groundwater remediation system (before and after termination of the system’s operation on September 28, 2012) on groundwater flow and quality.

Documenting volatile organic compound (VOC) water quality relative to Montana groundwater standards.

This report describes methods and results of bi-annual groundwater monitoring completed at the BVSL in July 2014. Validated monitoring data obtained from individual properties has been transmitted directly to involved property owners.

Key Findings from the July 2014 Groundwater Monitoring Event

The following key findings from the July 2014 monitoring event are presented in terms of the Project obligations are based on the wells sampled. BVSL hydrostratigraphic terminology referenced below is defined in Appendix A.

1. Tracking Temporal and Spatial Trends in Groundwater Flow and Quality

Groundwater Flow

With the reduced scope of groundwater sampling, the limited data set of groundwater elevations does not allow for accurate potentiometric surface mapping. It is assumed that the conditions in July 2014 mimic previous summer sampling event data with respect to groundwater flow direction and gradient. A review of groundwater monitoring well data indicate on average that water levels are higher in 2014 than in 2013 (Tetra Tech 2014a)(+1.26 to +6.44 feet). These water level increases represent approximately a 1.5% to 8% change over the total range of piezometric head across the site.

SMART Consulting and Tetra Tech ii September 2014

Chloroform in the Shallow Portion of Unit A

Shallow Unit A well BR-GW-41S did not contained any chloroform over the reporting limit in July 2014 as compared to 0.58 µg/L chloroform in July 2013 (Tetra Tech 2014a).

Concentrations in this well have decrease dramatically over the last nine years;

chloroform concentrations in June 2004 were 190 µg/L.

Chloroform in the Deep Portion of Unit A

Chloroform was detected in wells BR-GW-34D, -36D, R-9D, SA-13, and BR-GW-90DD.

The most significant observation of these results when compared to previously sampling events was a noted decrease in well R-9D, from 158 µg/L in July 2013 to 115 µg/L in July 2014.

Chloroform in the Unit B The chloroform concentration in the sample from well BR-GW-61DD also decreased from 66 µg/L in July 2013 to 55 µg/L in July 2014.

Chloroform in Units C and D (Replacement Wells)

Chloroform was not detected in samples from the replacement domestic wells monitored in Unit C (BR-GW-65DD) and Unit D (BR-GW-76DD and BR-GW-79DD).

Comparison from Previous Sampling

A Comparison of the chloroform concentrations detected in groundwater samples from the wells collected in July 2014 versus samples collected in July 2013 is provided below:

Detected Chloroform Concentration Comparisons in Wells between July 2014 and 2013

Well July 2014 July 2013

R-8D 0.27 J µg/L NS

R-9D 115 µg/L 158 µg/L

SA-13 53 µg/L 55 µg/L

BRGW-34D 4.6 µg/L 5.6 µg/L

BRGW-36D 88 µg/L 85 µg/L

BRGW-41S ND 0.58 µg/L

BRGW-51D 3.9 µg/L NS

BRGW-61DD 56 µg/L 66 µg/L

BRGW-90D 2.6 µg/L NS

Notes:

J flagged as an estimated concentration by the lab. ND not detected above the laboratory reporting limit. NS not sampled.

Other VOCs

Vinyl chloride was detected in shallow Unit A well monitoring well BR-GW-41S at 0.66 µg/L and deep Unit A well R-8D at 4.2 µg/L which is over the 1999 Circular WQB-7 standard of 0.15 µg/L. No other VOCs were detected in July 2014 samples at concentrations in excess of the WQB-7 standards.

SMART Consulting and Tetra Tech iii September 2014

Trends of VOC compounds detected in monitoring and/or domestic replacement wells are posted as follows:

BR-GW-41S contained vinyl chloride (0.66 µg/L) which was slightly less than the previous July sample event concentration (0.86 µg/L). An assortment of other VOC were also present which is also consistent other sample events.

R-8D contained vinyl chloride (4.2 µg/L); it was not sampled in July 2013. An assortment of other VOC were also present in the sample which is also consistent other sample events.

BR-GW-61DD contained multiple VOCs at very low concentrations which is consistent with previous winter events.

All VOCs in BR-GW-65DD were below reporting limits except dichlorodifluoromethane (DCDMF) which was estimated at 0.47 µg/L. This is also consistent with results over last several monitoring events. This well sample is from the Larson domestic replacement well; however the water quality standard is 1,400 µg/L, therefore these results pose very little risk (below acceptable risk thresholds) to the residents.

BR-GW-76DD and BR-GW-79DD All VOCs were below MDLs, consistent with previous sample events.

D-101 contained 2.1 µg/L chloroform, 0.11 µg/L (estimated) DCDMF, and 0.15 µg/L (estimated) tetrachloroethene. This is the J. Metcalf domestic well that was installed by others without oversight or direction by NIH or Montana DEQ. It is has recently been added to the list of domestic wells to be sampled under the 2014 Groundwater Monitoring Work Plan (Tetra Tech 2014).

2. Evaluating the Effect of NIH's 1993-94 Soil Removal Action and Effects of NIH’s Phase IIA Groundwater Remediation System on Groundwater Flow and Quality

Based on the Settlement Agreement, NIH’s commitment for groundwater monitoring extends for a 5 year period after shutdown of the Phase IIA groundwater remediation system. NIH shut down the Phase IIA system on September 28, 2012 and will continue to conduct groundwater monitoring until September 28, 2017.

3. Documenting VOC Water Quality Relative to Montana Groundwater Standards.

Several groundwater samples exhibited VOCs concentrations that exceeded the WQB-7 groundwater standards (DEQ 1999). These groundwater samples are listed below according to their hydrostratigraphic unit with WQB-7 groundwater standards and their respective sample concentrations in parentheses.

Shallow Portion of Unit A Vinyl Chloride (0.15 µg/L) – Sample from well BR- GW-41S (0.66 µg/L).

Deep Portion of Unit A Chloroform (60 g/L) – Samples from wells R-9D (115 µg/L) and BR-GW-36D (88 µg/L). Vinyl Chloride (0.15 µg/L) – Sample from well R-8D (4.2 µg/L).

SMART Consulting and Tetra Tech iv September 2014

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY .............................................................................................................. I

1.0 INTRODUCTION

2.0 METHODS

2.1 WATER LEVEL MEASUREMENT

2.2 GROUNDWATER SAMPLING AND ANALYSIS

3.0 DATA PRESENTATION AND INTERPRETATION

3.1 GROUNDWATER ELEVATION AND FLOW

3.2 GROUNDWATER EXCEEDING STANDARDS

3.3 CHLOROFORM DISTRIBUTION AND TRENDS

3.4 OTHER VOCS

3.5 OPERATING AND MAINTAINING THE PHASE IIA GROUNDWATER TREATMENT

SYSTEM

4.0 DATA VALIDATION

4.1 FIELD QUALITY ASSURANCE/QUALITY CONTROL

4.2 LABORATORY QUALITY ASSURANCE/QUALITY CONTROL

5.0 REFERENCES

LIST OF FIGURES

FIGURE 1 Location and Vicinity Map FIGURE 2 Facility Map FIGURE 3 Chloroform Concentrations vs Time in Select Wells FIGURE 4 Chloroform Concentrations in Shallow Portion Unit A FIGURE 5 Chloroform Concentrations in Deep Portion Unit A FIGURE 6 Tetrachloroethene Concentrations in Shallow Portion Unit A FIGURE 7 Tetrachloroethene Concentrations in Deep Portion Unit A

LIST OF TABLES

TABLE 1 Wells Monitored, July 2014 TABLE 2 Detected Chloroform Concentration Comparisons in Wells July 2014 and 2013 TABLE 3 Summary of March 2014 Groundwater Analytical Data

LIST OF APPENDICES

APPENDIX A Hydrostratigraphic Terminology APPENDIX B Well Inventory Database APPENDIX C Field Sampling Logs APPENDIX D July 2014 Water Elevation Data APPENDIX E July 2014 Groundwater Volatile Organic Compound Data APPENDIX F July 2014 Groundwater Physical Parameter Data APPENDIX G July 2014 Laboratory QA/QC Summary Reports APPENDIX H Historical Groundwater Volatile Organic Compound Data (CD)

SMART Consulting and Tetra Tech 1 September 2014

1.0 INTRODUCTION

In November 2000, the United States on behalf of the National Institutes of Health (NIH) and the State of Montana on behalf of the Montana Department of Environmental Quality (DEQ) entered into a Settlement Agreement regarding the Bitterroot Valley Sanitary Landfill (BVSL). The Settlement Agreement generally establishes the requirements for groundwater monitoring at BVSL. The full details of the groundwater monitoring required by the Settlement Agreement are contained in the groundwater monitoring plans which have been mutually agreed upon by the DEQ and the NIH. The previous groundwater monitoring plan (Amended Final Work Plan Groundwater Monitoring, Maxim 2002) guided groundwater monitoring between January 2003 and July 2013. The current groundwater monitoring plan (2014 Amendment to the December 2002 Amended Final Work Plan; Tetra Tech 2014b) is an amendment to the December 2002 Amended Final Work Plan and provides the basis for that monitoring in acknowledgement of the agreements between NIH and DEQ. The 2014 Work Plan supersedes all others. Specific details regarding the requirements of the Settlement Agreement are provided in the specific sections of the Work Plan.

The DEQ’s selected cleanup alternative for BVSL includes the design and construction of a community water supply system (CWSS), implementation of institutional controls, natural attenuation of groundwater contamination, and groundwater monitoring. NIH’s obligation under the Settlement Agreement ended with respect to the community water supply system with a force majeure event with the exception of groundwater monitoring. Institutional controls were created in the form of a controlled groundwater area established and administered through the Montana Department of Natural Resources and Conservation (DNRC). The current Work Plan focuses on the remaining NIH obligations for groundwater monitoring. Those obligations are:

Tracking temporal and spatial trends in groundwater flow and quality.

Evaluating the effects of NIH's 1993-94 soil removal action and effects of NIH’s Phase IIA groundwater remediation system (before and after termination of the system’s operation on September 28, 2012) on groundwater flow and quality.

Documenting volatile organic compound (VOC) water quality relative to Montana groundwater standards.

This report describes methods and results of bi-annual groundwater monitoring completed at the BVSL in July 2014. The July 2014 monitoring event was conducted according to procedures specified in the 2014 Amendment to the December 2002 Amended Final Work Plan (Tetra Tech 2014). In addition, validated monitoring data obtained from individual properties has been transmitted directly to involved property owners.

Bitterroot Valley Sanitary Landfill

USGS 7.5' Victor Topographic Quadrangle

FIGURE 1

Location MapBitterroot Valley Sanitary Landfill

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Victor, Montana

Montana

Victor Missoula

Ravalli County

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GW-34D

GW-51D

GW-90D

GW-31D

GW-91D

GW-36D

GW-83D

GW-42D

GW-50D

GW-54D

GW-38D

GW-86D

GW-92D

P-2

P-1

GW-8

R-7S

GW-3

GW-10

GW-85

GW-35S

GW-52S

GW-33SGW-32S

GW-55S

GW-30S

GW-39S

GW-41S

GW-58S

GW-49S

GW-60S

GW-88SGW-37S

GW-46S

GW-48S

GW-43S

GW-59S

GW-87S

GW-89S

GW-53S

GW-61DD

GW-56DD

OW-01D OW-02S D-53

GW-1

GW-5

D-101

GW-21

GW-18

D-26

GW-2

D-39

PW-01D PW-02S

R-2

R-5S

R-3S

R-1

R-4D

R-6DR-9D

R-10

R-8D

GW-84D

GW-73DD

GW-65DD

GW-63DD

GW-68DD

GW-71DD

GW-66DD

GW-72DD

GW-77DD

GW-67DD

GW-79DD

GW-78DD

GW-70DD

GW-80DD

GW-69DD

GW-75DD

GW-74DD

GW-76DD

GW-62DD

SA-4

SA-1

SA-8&9

SA16 & 17

SA-3

SA-2

SA-6&7SA-5

SA-14&15

SA-12&13

SA-10&11

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr. Rockland Dr.

Pine Ln.

North Channel Bear C reek

Ephemeral Drainage

Bitterroot River

Meridian Rd.

Highway 93

Vic tor

On e M ile

Phase II A Treatment Building

Copyright:© 2013 ESRI, i-cubed, GeoEye

March 2013 Figure 2Facility Map

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

Pa th:

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Coordinate System: GCS WGS 1984 Datum: WGS 1984 Units: Degree

2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service k Abandoned Well ! Monitoring Well + Other Well " Pumping Test Well

^ Observation Well # Recovery Well ^ Replacement Well E Source Area Characterization Well

Well Completed in Aquitard Between Units A and B Wells Completed in Shallow Portion Unit A Wells Completed in Deep Portion Unit A Wells Completed in Unit B Wells Completed in Unit C Wells Completed in Unit D

GW-40D

GW-60S

GW-54D

GW-84D

GW-73DD

GW-64DD

GW-81SGW-82D

GW-64DD Abandoned Well

SMART Consulting and Tetra Tech 4 September 2014

On July 3 2014, groundwater samples and depth to water measurements were collected from 12 wells/sample points (Table 1). Several samples were incorporated into the sample train for quality assurance/quality control (QA/QC) purposes, including:

Temperature blanks for each cooler were shipped to the laboratory;

One trip blank prepared by the laboratory shipped with the sample containers for VOC analyses;

One field blank prepared Tetra Tech in the field for VOC analyses; one blind field duplicate collected from well BR-GW-36D was analyzed for VOC.

Samples were sent to Energy Laboratories, Inc. (ELI) for the analysis of VOCs.

Groundwater analytical results were compared to Circular WQB-7 groundwater standards published in September 1999 (WQB-7, DEQ 1999), which are referenced in DEQ's Record of Decision (DEQ 2002). The analytical data compiled from this sampling event are presented in Appendices E, F, and G and historical well data is presented in Appendix H on CD.

The following sections of this report describe groundwater monitoring methods, present water level and water quality data from the July 2014 monitoring event, and interpret the data. Later sections of the report discuss data validation for July 2014 samples and list cited references.

The hydrostratigraphic terminology developed for the project and a generalized hydrogeologic cross section of the facility are presented in Appendix A. Other supporting information including water level, VOC, and physical parameters are contained in Appendices C through H.

SMART Consulting and Tetra Tech 5 September 2014

2.0 METHODS

Bi-annual groundwater monitoring at BVSL was conducted from June 30 through July 3, 2014, groundwater samples were collected from 13 wells/sample points. Water levels of all non-domestic monitoring points were also measured (Table 1). A duplicate sample was collected from BR-GW-61DD. Groundwater monitoring methods are described below.

2.1 WATER LEVEL MEASUREMENT

Field staff measured depth to water in wells listed in Table 1 (well locations are shown on Figure 2) using a decontaminated electric water level indicator. Water level measurements were recorded on field sampling logs (Appendix C) and entered into the project database (Appendix D).

Domestic replacement wells were not gauged this sampling event (as agreed upon by DEQ) because of the potential to introduce contaminants into the domestic supply.

2.2 GROUNDWATER SAMPLING AND ANALYSIS

Groundwater samples were collected from 13 wells/sample points for VOC analysis (Table 1).

Each well was purged of approximately three well casing volumes of water, or more, prior to sampling. During and after well purging, groundwater was directed through an instrumented cell where physical parameters such as pH, temperature, specific conductance, oxidation-reduction potential (Eh), and dissolved oxygen were measured with a calibrated QED Hydrolab® meter.

Field parameter data were recorded on groundwater sampling logs for each well (Appendix C).

Groundwater samples collected for VOC analysis were packed in ice and shipped with chain-of-custody documentation to ELI in Billings, Montana for VOC analysis by EPA Method 524.2.

Several samples were incorporated into the sample train for quality assurance/quality control (QA/QC) purposes, including:

Temperature blanks for each cooler were shipped to the laboratory;

One trip blank prepared by the laboratory shipped with the sample containers for VOC analyses;

One field blank prepared Tetra Tech in the field for VOC analyses;

One blind field duplicate collected from well BR-GW-36D was analyzed for VOC.

Details of QA/QC procedures are provided in Section 4.0.

SMART Consulting and Tetra Tech 6 September 2014

TABLE 1

Wells Monitored, July 2014

Well Number

Well Type

DTW VOCs

BR-GW-34D M ● ●

BR-GW-36D M ● ●

Blind Dup. of BR-

GW-36D

M ●

BR-GW-41S M ● ●

BR-GW-51D M ● ●

BR-GW-61DD M ● ●

SA-13 M ● ●

R-8D M ● ●

R-9D M ● ●

BR-GW-65DD DD ●

BR-GW-76DD DD ●

BR-GW-79DD DD ●

BR-GW-90D M ● ●

D-101 D ●

Notes: DTW depth to water, VOCs volatile organic compounds, M monitoring well, DD replacement domestic well, D domestic well (private) .

SMART Consulting and Tetra Tech 7 September 2014

3.0 DATA PRESENTATION AND INTERPRETATION

This section presents results of July 2014 bi-annual groundwater monitoring. Field sampling logs, water elevation data, groundwater VOC data, and groundwater physical parameter data are provided in Appendices C through F, respectively. Groundwater flow and quality data collected from the current reporting event, along with interpretations of the data, are discussed below.

3.1 GROUNDWATER ELEVATION AND FLOW

Depth to water and groundwater elevation data for July 2014 are presented in Appendix D.

With the reduced scope of groundwater sampling, the limited data set of groundwater elevations does not allow for accurate potentiometric surface mapping. It is assumed that the conditions in July 2014 mimic previous year’s data with respect to groundwater flow direction and gradient. A review of nine groundwater monitoring well data indicate on average that water levels are higher in 2014 than in 2013 (+0.3 to +4.17 feet); the exception being wells R-9D and SA-13, which were slightly lower in elevation (+1.26 to +6.44 feet). These water level increases represent approximately a 1.5% to 8% change over the total range of piezometric head across the site.

3.2 GROUNDWATER EXCEEDING STANDARDS

Table 2 summarizes July 2014 groundwater VOC data. Appendices E and F contain databases with the sample data. Several groundwater samples exhibited VOCs concentrations that exceeded the WQB-7 groundwater standards (DEQ 1999). These groundwater samples are listed below according to their hydrostratigraphic unit with WQB-7 groundwater standards and their respective sample concentrations in parentheses.

Shallow Portion of Unit A

Vinyl Chloride (0.15 µg/L) – Sample from well BR-GW-41S (0.66 µg/L)

Deep Portion of Unit A

Chloroform (60 g/L) – Samples from wells R-9D (115 µg/L) and BR-GW-36D (88 µg/L)

Vinyl Chloride (0.15 µg/L) – Sample from well R-8D (4.2 µg/L)

3.3 CHLOROFORM DISTRIBUTION AND TRENDS

Chloroform groundwater quality in most wells generally continues to improve as a direct result of the 1993-94 soil cleanup remedial action, 1998-2012 Phase IIA groundwater remediation, and natural attenuation. Recent and historic trends in chloroform concentrations in selected monitoring wells are shown on Figure 3.

Shallow Portion of Unit A

Chloroform was not detected above the laboratory reporting limit from Shallow Unit A well BR- GW-41S versus 0.58 µg/L in July 2013. Concentrations in this well have decrease dramatically over the last nine years; chloroform concentrations in June 2004 were 190 µg/L. A historical database of VOC water quality data is provided in Appendix H. The chloroform concentration in well BR-GW-41S for the shallow portion of the Unit A aquifer is posted on Figure 4.

Chloroform in the Deep Portion of Unit A

A Comparison of the chloroform concentrations observed in groundwater samples from the wells completed in the deep portion of Unit A collected in July 2014 versus samples collected in July 2013 revealed the following (Table 2):

SMART Consulting and Tetra Tech 8 September 2014

Chloroform was again detected in wells BR-GW-34D, -36D, R-9D, SA-13, and BR-GW- 90DD. Chloroform was detected in D-101; this marks the first time this well has been sampled in over five years.

The chloroform concentrations in the eight sampled wells in the deep portion of the Unit A aquifer are posted on Figure 5. Comparisons to concentrations in July 2013 are posted below:

BR-GW-36D (88 µg/L, up from 85 µg/L) SA-13 (53 µg/L, down from 55 µg/L) R-9D (115 µg/L, down from 158 µg/L) R-8D (0.27µg/L, not sampled in July 2013) BR-GW-90D (2.6 µg/L, not sampled in July 2013) BR-GW-34D (4.6 µg/L, down from 5.6 µg/L) BR-GW-51D (3.9 µg/L, not sampled in July 2013) D-101 (2.1 µg/L, not sampled in July 2013)

Chloroform in Unit B

The chloroform concentration in the sample from well BR-GW-61DD decreased in July 2014 compared to July 2013 (56 µg/L from 66 µg/L) (Table 2).

Chloroform in Units C and D (Replacement Wells)

Chloroform was not detected in samples from three of the replacement domestic wells monitored in Unit C (BR-GW-65DD) and Unit D (BR-GW-76DD and BR-GW-79DD).

SMART Consulting and Tetra Tech 9 September 2014

TABLE 2

Detected Chloroform Concentration Comparisons in Wells July 2014 and 2013

Well July 2014 July 2013

R-8D 0.27 J µg/L NS

R-9D 115 µg/L 158 µg/L

SA-13 53 µg/L 55 µg/L

BRGW-34D 4.6 µg/L 5.6 µg/L

BRGW-36D 88 µg/L 85 µg/L

BRGW-41S ND 0.58 µg/L

BRGW-51D 3.9 µg/L NS

BRGW-61DD 56 µg/L 66 µg/L

BRGW-90D 2.6 µg/L NS

Notes: J flagged as an estimated concentration by the lab. ND not detected above the laboratory reporting limit. NS not sampled.

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GW-34D

GW-51D

GW-90D

GW-31D

GW-91D

GW-82D

GW-36D

GW-83D

GW-42D

GW-50D

GW-54D

GW-38D

GW-86D

GW-92D

P-2

P-1

GW-8

R-7S

GW-3

GW-10

GW-85

GW-35S

GW-52S

GW-33S

GW-32S

GW-81S

GW-55S

GW-30S

GW-39S

GW-41S

GW-58S

GW-49S

GW-60S

GW-88SGW-37S

GW-46S

GW-48S

GW-43S

GW-59S

GW-87S

GW-89S

GW-53S

GW-61DD

GW-56DD

OW-01D OW-02S D-53

GW-1

GW-5

D-101

GW-21

GW-18

D-26

GW-2

D-39

PW-01D PW-02S

R-2

R-5S

R-3S

R-1

R-4D

R-6DR-9D

R-10

R-8D

GW-84D

GW-73DD

GW-65DD

GW-63DD

GW-68DD

GW-71DD

GW-66DD

GW-72DD

GW-77DD

GW-67DD

GW-79DD

GW-78DD

GW-70DD

GW-80DD

GW-69DD

GW-75DD

GW-74DD

GW-76DD

GW-62DD

SA-4

SA-1

SA-8&9

SA-16 & 17

SA-3

SA-2

SA-6&7SA-5

SA-14&15SA-12&13

SA-10&11

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr. Rockland Dr.

Pine Ln.

North Channel Bear C reek

Ephemeral Drainage

Bitterroot River

Meridian Rd.

Highway 93

Vic tor

On e M ile

Phase II A Treatment Building

Source Removal Area

Copyright:© 2013 ESRI, i-cubed, GeoEye

July 2014 Figure 3Chloroform Concentration vs Time

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

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2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service ! Monitoring Well + Other Well " Pumping Test Well

* Observation Well

# Recovery Well ^ Replacement Well E Source Area Characterization Well

1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000

'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

BR-GW-36D

Note: Phase II A System deactivated April 28 - September 27, 2004 for shut-down study (Maxim, 2004a)

NM

'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

Ch loro form Co nce ntra tion (µg

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BR-GW-61DD

1,000 1,200 1,400 1,600 1,800 2,000

'99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10

Ch loro form Co nce ntra tion (µg

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R-9D

'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

Ch loro form Co nce ntra tion (µg

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R-8D

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

Ch loro form Co nce ntra tion (µg

/L)

SA-13

0.00

0.10

0.20

0.30

0.40

0.50

0.60

'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

Ch loro form Co nce ntra tion (µg

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BRGW-79DD

) Wells Completed in Deep Portion Unit A ) Wells Completed in Shallow Portion Unit A ) Wells Completed in Unit B

Wells Completed in Unit B

'99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

Ch loro form Co nce ntra tion (µg

/L)

BR-GW-90D

'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

BR-GW-34D

1,000

'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

BR-GW-41S

'92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14

BR-GW-51D

'99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14 '15

D-101

Ch lor ofo rm

Co nce ntr ati on (µ g/L

Ch lor ofo rm

Co nce ntr ati on (µ g/L

Ch lor ofo rm

Co nce ntr ati on (µ g/L

Ch lor ofo rm

Co nce ntr ati on (µ g/L

Ch lor ofo rm

Co nce ntr ati on (µ g/L

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr.

North Channel Bear C reek

Ephemeral Drainage

Bit te rroot River

Meridian Rd.

Highway 93

Vic tor

On e M ile

Phase II A Treatment Building

Source Removal Area

<0.5

GW-81S

P-2

P-1

R-2

R-1

D-26

R-5S

R-3S

GW-8

R-7S

GW-3

GW-2

GW-10GW-85

GW-35S

GW-52S

GW-33S

OW-02S

PW-02S

GW-32S

GW-55S

GW-30S

GW-39S

GW-41S

GW-58S

GW-49S

GW-60S

GW-88S

GW-37SGW-46S

GW-48S

GW-43S

GW-59S

GW-87S

GW-89S

GW-53S

Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

July 2014 Figure Chloroform Concentrations in Shallow Portion Unit A

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

Pa th:

G :\E nv iro nm en tal

\BV

SL

\G

IS

\m xd \Ju ly

\C hlo r_S ha lAJ uly .m xd

Coordinate System: GCS WGS 1984 Datum: WGS 1984 Units: Degree

2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service

20.9 Chloroform Concentration (µg/L)

* Observation Well # Recovery Well ^ Replacement Well ! Monitoring Well

+ Other Well " Pumping Test Well E Source Area Characterization Well

Abandoned!@

Wendy.Largent Text Box Figure 4

EE

E

EE

EE

E EE

E EE

EE

EE

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr. Rockland Dr.

Pine Ln.

North Channel Bear C ree k

Ephemeral Drainage

Bitterroot River

Meridian Rd.

Highway 93

Vic tor

On e M ile

Phase II A Treatment Building

Source Removal Area

4.6

0.27J

2.1

2.6

3.9

P-3

D-53

GW-9

R-9D

SA-4

SA-1

SA-3

GW-1

GW-5

R-4D

R-6DR-10

R-8D

D-101

SA-16 & 17

SA-12 & 13

GW-21

GW-18

GW-34D

GW-51D

GW-90D

OW-01D

PW-01D

GW-31D GW-91D

GW-82DGW-83D

GW-42D

GW-50D

GW-54D

GW-38D

GW-86D

GW-92D

GW-36D

SA-10 & 11

SA-14 & 15

SA-5

SA-6 & 7

SA-8 & 9

SA-2

Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community July 2014 Figure 5Chloroform Concentrations in Deep Portion Unit A

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

Pa th:

G :\E nv iro nm en tal

\BV

SL

\G

IS

\m xd \Ju ly

\C hlo r_D ee pA

Ju ly2

4.m xd

Coordinate System: GCS WGS 1984 Datum: WGS 1984 Units: Degree

2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service

EE

E

EE

EE

E

E

E

ESA-4

SA-1 SA-3SA-2

SA-8 & 9

SA-6 & 7

SA-5

SA-10 & 11

20.9 Chloroform Concentration (µg/L)

* Observation Well # Recovery Well ^ Replacement Well ! Monitoring Well

+ Other Well " Pumping Test Well E Source Area Characterization Well

Abandoned!@

SMART Consulting and Tetra Tech 13 August 2014

3.4 OTHER VOCS

Vinyl chloride was detected in shallow Unit A well monitoring well BR-GW-41S at 0.66 µg/L and deep Unit A well R-8D at 4.2 µg/L which is over the 1999 Circular WQB-7 standard of 0.15 µg/L.

No other VOCs (besides chloroform and vinyl chloride) were detected in July 2014 samples at concentrations in excess of the WQB-7 standards.

VOCs of interest detected in the July 2014 sampling event include benzene, chloroethane, chloroform, dichloro-difluoromethane (DCDFM), 1,4-dichlorobenzene,1,1-dichloroethane (DCA), cis-1,2-dichloroethene (DCE), trans-1,2-dichloroethene (DCE), tetrachloroethene (PCE), toluene, 1,1,1 trichloroethane (TCE), trichloroethene, trichloro-fluoromethane, and vinyl chloride (VC). Because PCE is present in most wells tested for VOCs that also contain chloroform, it is another indicator tool that has been utilized in the past to outline the plume maps in the shallow and deep portions of the Unit A aquifer. However, due to the fact that the number of wells sampled during the reduce scope of monitoring is not sufficient to map VOC contaminant plume, post maps with PCE concentrations have been provided in Figures 6 and 7.

Trends of VOC compounds detected in monitoring wells, private domestic, and domestic replacement wells are posted as follows:

BR-GW-41S contained vinyl chloride (0.66 µg/L) which was slightly less than the previous July sample event concentration (0.86 µg/L). An assortment of other VOC compounds was also present which is also consistent with other sample events.

R-8D contained vinyl chloride (4.5 µg/L), which was not previously sampled in July 2013.

An assortment of other VOC compounds was also present at very low concentrations.

BR-GW-61DD (Contained multiple other VOCs are very low concentrations which is consistent with previous winter events.)

BR-GW-65DD contained dichlorodifluoromethane (DCDMF) at an estimated concentration of 0.47 µg/L. This is also consistent with results over last several monitoring events. This well sample is from the Larson domestic replacement well;

however the water quality standard is 1,400 µg/L, and therefore these results pose very little risk (below acceptable risk thresholds) to the residents.)

BR-GW-76DD and BR-GW-79DD (All VOCs were below reporting limits, consistent with previous sample events).

D-101 (All VOCs were below reporting limits except chloroform, DCDMF, and PCE).

PCE, TCE, cis-1,2 DCE, and VC are all chlorinated ethenes that have been detected in groundwater from BVSL wells and were not reported to have been disposed of in the historic waste pit (Maxim 1998c). Under anaerobic conditions, cis-1,2 DCE and VC can be formed as a breakdown product from the reductive dehalogenation of TCE and PCE. Although the source of cis-1,2 DCE and VC in groundwater at the BVSL is not known, it is NIH’s opinion that the chlorinated ethenes are most likely related to the breakdown of PCE and TCE in buried refuse rather than the waste disposal pit.

3.5 OPERATING AND MAINTAINING THE PHASE IIA GROUNDWATER TREATMENT

SYSTEM

Based on the Settlement Agreement, NIH’s commitment for groundwater monitoring extends for a 5 year period after shutdown of the Phase IIA groundwater remediation system. NIH shut down the Phase IIA system on September 28, 2012 and will continue to conduct groundwater monitoring until September 28, 2017.

Dichloro-benzene

Dichloro-ethane

1,4- 1,1-

Dichloro-ethane ethene

Dichloro- Dichloro-ethene ethene

Dichloro-benzene

Ethyl-chloride

Methylene-ethene chloro-

Toluene ethane

Trichloro-ethene

Trichloro-methane

Fluoro-

Chloride

Vinyl

Xylenes

Total

Tetra- Trichloro-1,2- 1,1- Cis-1,2- T-1,2- 1,1,1

TABLE 3

SUMMARY OF JULY 2014 GROUNDWATER DATA

Bitterroot Valley Sanitary Landfill

DateLocation

Carbon chloride

Tetra- Chloro-benzene

Chloro-ethane

Sample

Benzene

Bromo-methane

Chloro-methane

Chloro-form

Dichloro-difluoro-methane

BRGW-31D 6/13/2012 0.4J 26 0.35J

BRGW-31D 7/11/2013 0.27J 19 0.29J

BRGW-34D 6/13/2012 0.26J 4.9 0.21J

BRGW-34D 7/11/2013 0.26J 5.6 0.28J

BRGW-34D 7/3/2014 0.27J 4.6 0.22J

BRGW-36D 6/18/2012 0.16J 8

BRGW-36D 7/11/2013 0.14J 0.40J 88 0.17J

BRGW-36D 7/11/2013 0.16J 0.41J 85 0.18J

BRGW-36D 7/3/2014 0.1J 0.4J 88 0.19J 0.18J

BRGW-36D* 7/3/2014 0.16J 0.42J 0.13J 86 0.18J 0.16J

BRGW-41S 6/18/2012 11.0 1 0.12J 0.29J 1.7 0.79 0.25J

BRGW-41S 7/11/2013 9.9 0.64 0.86 0.45J0.40J 0.58 0.43J 0.74

BRGW-41S 7/3/2014 28 1.2J 0.42J 0.66 0.690.29J 1.5 0.49J 0.27J 0.7 0.19J

BRGW-51D 7/3/2014 0.19J 3.9 0.18J

BRGW-61DD 6/13/2012 0.68 1.7 0.16J0.33J 67 1.5 0.38J

BRGW-61DD 7/10/2013 0.71 1.4 0.17J0.35J 66 1.3 0.26J

BRGW-61DD 7/3/2014 0.61 1.4 0.14J0.26J 56 1.5 0.36J

BRGW-62DD 6/11/2012

BRGW-62DD 6/13/2012

BRGW-62DD 7/26/2012

BRGW-62DD 7/9/2013

BRGW-62DD 8/29/2013

BRGW-62DD 9/11/2013

BRGW-65DD 6/11/2012 0.14J 0.33J

BRGW-65DD 7/8/2013 0.44J

BRGW-65DD 7/29/2013

BRGW-65DD 7/3/2014 0.47J

BRGW-66DD 6/11/2012

BRGW-66DD 6/11/2012

BRGW-66DD 7/12/2012

BRGW-66DD 7/8/2013

BRGW-66DD 8/29/2013

BRGW-67DD 6/12/2012

BRGW-67DD 6/20/2012

BRGW-67DD 8/1/2012

BRGW-68DD 6/11/2012

BRGW-68DD 7/26/2012

BRGW-68DD 7/9/2013

BRGW-68DD 8/29/2013

BRGW-68DD 9/11/2013

BRGW-68DD 10/3/2013

BRGW-69DD 6/12/2012

BRGW-70DD 6/12/2012

BRGW-70DD 6/12/2012

BRGW-70DD 7/26/2012

BRGW-70DD 7/10/2013

BRGW-70DD 8/29/2013

BRGW-71DD 6/11/2012

BRGW-71DD 6/13/2012

BRGW-71DD 7/12/2012

BRGW-71DD 7/9/2013

BRGW-71DD 8/29/2013

BRGW-72DD 6/12/2012

BRGW-72DD 7/8/2013

BRGW-73DD 6/11/2012 0.35J

BRGW-73DD 6/11/2012

BRGW-73DD 7/9/2013 0.40J

BRGW-74DD 6/12/2012

BRGW-74DD 6/18/2012

BRGW-74DD 8/1/2012

BRGW-74DD 7/8/2013

BRGW-76DD 7/3/2014

BRGW-77DD 6/12/2012

BRGW-77DD 6/18/2012

BRGW-77DD 8/1/2012

BRGW-77DD 7/9/2013

BRGW-77DD 7/29/2013

BRGW-77DD 10/22/2013

BRGW-79DD 7/3/2014

G:\DatabaseInfo\BVSLDbase\bvsl2k.mdb <Table_2_Summary.rpt> Tetra Tech

Montana GW Standard 5 48 3 --100 75 -- 4 728 60 1,400 70 100 700 5 5 1,000 200 5 10,000 0.15 10,000

NOTES:

- All concentrations in micrograms per liter

- Montana GW (Groundwater) Standard from WQB-7 (9-99)- Blank cell indicates not detected above the practical quantitation limit

- Compounds listed are those that have been detected at least once since 1992 - Shading indicates over Montana GW Standard

J - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.

* - Duplicate +/- - Total Coliform Presence/Absense

** - Lab Duplicate

Dichloro-

Dichloro-ethane

1,4- 1,1-

Dichloro-ethane ethene

Dichloro- Dichloro-ethene ethene

Dichloro-benzene

Ethyl-chloride

Methylene-ethene chloro-

Toluene ethane

Trichloro-ethene

Trichloro-methane

Fluoro-

Chloride

Vinyl

Xylenes

Total

Tetra- Trichloro-1,2- 1,1- Cis-1,2- T-1,2- 1,1,1

TABLE 3

SUMMARY OF JULY 2014 GROUNDWATER DATA

Bitterroot Valley Sanitary Landfill

DateLocation

Carbon chloride

Tetra- Chloro-benzene

Chloro-ethane

Sample

Benzene

Bromo-methane

Chloro-methane

Chloro-form

Dichloro-difluoro-methane

BRGW-80DD 6/11/2012

BRGW-80DD 6/12/2012

BRGW-80DD 7/8/2013

BRGW-84D 6/12/2012

BRGW-84D 6/18/2012

BRGW-84D 7/8/2013

BRGW-90D 7/3/2014 2.6

D-101 7/3/2014 0.15J 2.1 0.11J

R-8D 7/3/2014 60 2.2 4.2 4.60.59 0.27J 0.55 1 3.1 0.98

R-9D 6/13/2012 0.38J 91

R-9D 7/11/2013 0.46J 158 0.19J

R-9D 7/3/2014 0.11J 0.4J 115 0.2J 0.15J

SA-13 6/18/2012 0.29J 34

SA-13 7/11/2013 0.18J 0.36J 55

SA-13 7/3/2014 0.34J 53 0.089J

G:\DatabaseInfo\BVSLDbase\bvsl2k.mdb <Table_2_Summary.rpt> Tetra Tech

Montana GW Standard 5 48 3 --100 75 -- 4 728 60 1,400 70 100 700 5 5 1,000 200 5 10,000 0.15 10,000

NOTES:

- All concentrations in micrograms per liter

- Montana GW (Groundwater) Standard from WQB-7 (9-99)- Blank cell indicates not detected above the practical quantitation limit

- Compounds listed are those that have been detected at least once since 1992 - Shading indicates over Montana GW Standard

J - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.

* - Duplicate +/- - Total Coliform Presence/Absense

** - Lab Duplicate

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr.

North Channel Bear C reek

Ephemeral Drainage

Bit te rroot River

Meridian Rd.

Highway 93

Vic tor

On e M ile

Phase II A Treatment Building

Source Removal Area

GW-81S

P-2

P-1

R-2

R-1

D-26

R-5S

R-3S

GW-8

R-7S

GW-3

GW-2

GW-10GW-85

GW-35S

GW-52S

GW-33S

OW-02S

PW-02S

GW-32S

GW-55S

GW-30S

GW-39S

GW-41S

GW-58S

GW-49S

GW-60S

GW-88S

GW-37S

GW-46S

GW-48S

GW-43S

GW-59S

GW-87S

GW-89S

GW-53S

<0.50

Source: Esri, DigitalGlobe, GeoEye, i-cubed, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community, Copyright:© 2013 ESRI, i-cubed, GeoEye

July 2014 Figure 6Tetrachloroethene Concentrations in Shallow Portion Unit A

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

Pa th:

G :\E nv iro nm en tal

\BV

SL

\G

IS\

mx d\J uly

\TC

_S ha llo wA _J uly

.m xd

Coordinate System: GCS WGS 1984 Datum: WGS 1984 Units: Degree

2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service

Tetrachloroethene Concentration (µg/L)

0.5

Abandoned!@* Observation Well # Recovery Well ^ Replacement Well ! Monitoring Well

+ Other Well " Pumping Test Well E Source Area Characterization Well

EE

E

EE

EE

E EE

E EE

EE

EE

Bitterroot Valley Sanitary Landfill

Humdinger Ln.

Dinger Ln.

Westview Dr. Rockland Dr.

Pine Ln.

No rth Channel Bear Cr eek

Ephemeral Drainage

Bitter root River

Meridian Rd.

Highway 93

Phase II A Treatment Building

Source Removal Area

GW-90D

0.27J

0.4J

0.4J

0.34J

0.19J

<0.5

0.15J

2.2 P-3

D-53

GW-9

R-9D

SA-4

SA-1

SA-3

GW-1

GW-5

R-4D

R-6DR-10

R-8D

D-101

SA-16 & 17

SA-12 & 13

GW-21

GW-18

GW-34D

GW-51D

OW-01D

PW-01D

GW-31D

GW-91D

GW-82D

GW-83D

GW-42D

GW-50D

GW-54D

GW-38D

GW-86D

GW-92D

GW-36D

SA-10 & 11

SA-14 & 15

SA-5

SA-6 & 7

SA-8 & 9

SA-2

Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

July 2014 Figure Tetrachlorethene Concentrations in Deep Portion Unit A

Victor, Montana

0 500

SCALE IN FEET

Bitterroot Valley Sanitary Landfill

Pa th:

G :\E nv iro nm en tal

\BV

SL

\G

IS

\m xd \Ju ly

\TC

_D ee pA _J uly

.m xd

2009 ESRI, i-cubed, GeoEye ArcGIS Online World Imagery service

EE

E

EE

EE

E

E

E

ESA-4

SA-1 SA-3SA-2

SA-8 & 9

SA-6 & 7

SA-5

SA-10 & 11

* Observation Well # Recovery Well ^ Replacement Well ! Monitoring Well

+ Other Well " Pumping Test Well E Source Area Characterization Well

Tetrachloroethene Concentration (µg/L)

0.5

Abandoned!@

Wendy.Largent

Figure 7

SMART Consulting and Tetra Tech 18 September 2014

4.0 DATA VALIDATION

This section describes the data validation process used to determine the adequacy and quality of laboratory analytical data collected at the BVSL facility. The objective of data validation is to identify any unreliable or invalid laboratory measurements and qualify that data for interpretive use. Data validation was performed according to guidelines prepared by the U.S.

Environmental Protection Agency (USEPA 1994a and 1994b), and described in detail in Appendix A of the 2014 final groundwater monitoring work plan (Tetra Tech 2014).

4.1 FIELD QUALITY ASSURANCE/QUALITY CONTROL

Several samples were incorporated into the sample train for quality assurance/quality control (QA/QC) purposes, including:

Temperature blanks for each cooler were shipped to the laboratory;

One trip blank prepared by the laboratory shipped with the sample containers for VOC analyses;

One blind field duplicate collected from well BR-GW-36D was analyzed for VOC.

All field QA/QC samples were analyzed for VOCs by EPA Method 524.2. Analytical results for the natural and duplicate sample (Appendix E) were evaluated using the following criteria:

RPD- The relative percent difference (RPD) between the two samples was calculated when both values of the natural/duplicate pair were greater than five times the practical quantitation limit (PQL) for a given analyte. RPDs are calculated by dividing the difference between the paired reported concentrations for a given analyte by the average of the paired reported concentrations. Analytical results for natural/duplicate pairs exhibiting RPDs of greater than 20 percent are considered to be estimated concentrations.

Absolute Value- The absolute value of the difference between the natural and duplicate sample for a given analyte was calculated when one or both values were less than five times the PQL.

The natural/duplicate pair with values less than five times the PQL are considered estimated when the absolute value difference exceeds the PQL.

The RPD for chloroform was calculated for the blind duplicate sample of BR-GW-36D (Duplicate) for chloroform (the only VOC constituent detected that met the RPD criteria). The RPD calculated (0%) for this natural/duplicate pair was within the acceptable criterion.

The absolute value of the difference of the DCDFM, cis-1,2 Dichloroethene and PCE concentrations between BR-GW-61DD and Duplicate1 were less than the PQL.

All blank results were evaluated using the following criteria:

1. Analytical results of blank samples were reviewed to determine if any parameter was measured in the samples at detectable concentrations.

2. All results greater than the PQL but less than five times the concentration of the contaminated blank are considered estimated and are likely biased towards the high end.

3. The following constituents are common laboratory contaminants and are considered estimated when results are greater than the PQL but less than 10 times the concentration of the contaminated blank:

Methylene chloride Acetone

SMART Consulting and Tetra Tech 19 September 2014

Toluene 2-butanone Common phthalate esters

The VOC detections in the Field Blank include isopropyl benzene (0.15 µg/L J), naphthalene (0.15 µg/L J), toluene (0.13 µg/L J), 1,2,4-trimethylbenzene (0.24 µg/L J), and o-xylene (0.20 µg/L J). Isopropyl benzene, naphthalene, 1,2,4-trimethylbenzene, and o-xylene are not recognized COPCs and are not typically reported for the BVSL project; therefore these results will have no QC effect on the project. The toluene result from BR-GW-51D (1.2 µg/L) is over the PQL but less than 10 times the field blank result; the result has been modified to an estimated result (“J” flagged).

The Trip Blank sample prepared for the July 2014 sampling event did not contain any VOCs above the PQL (Appendix G, Field and Lab QC Sample Results).

4.2 LABORATORY QUALITY ASSURANCE/QUALITY CONTROL

VOC ANALYSIS

All samples for VOC analysis (except the Duplicate B14070391-014 and the Field Blank B14070391-015 samples) were received in acceptable condition, met preservative requirements and were analyzed within the holding times of the analytical method. The Duplicate and the Field Blank were inadvertently held at the lab but were not analyzed at Tetra Tech’s request.

After this error was spotted during review of the initial laboratory report, per Tetra Tech’s request, samples B14070391-014 (Duplicate) and B14070391-015 (Field Blank) were taken off hold and reported. The original value for Chloroform was 91 µg/L which was over the upper calibration range and the reported value from the dilution was 86 µg/L indicating that the holding time exceedance was not significant.

A copy of the laboratory QA/QC summary attached to each laboratory report is in Appendix G.

The samples were analyzed for VOCs using EPA method 524.2. The analyses were performed in a single analytical batch on July 7, 2014.

The data was reviewed against the quality control (QC) criteria as summarized below. Key points from laboratory QA/QC review include the following:

Calibration

The initial and continuing calibrations associated with this project all met method criteria for the VOC laboratory batches.

Blanks

A method blank consisting of reagent water must be analyzed with each batch. The method requires the method blank not contain any contaminants in concentrations greater than the reporting limit (RL). Target analytes were not found in any method blanks in excess of the RLs.

Laboratory Control Sample

A laboratory control sample (LCS) is to be analyzed once per batch. The acceptance criteria for the recovery of each analyte is typically 70 - 130%.

LCS recoveries were acceptable for the analytical batch.

Matrix Spike and Laboratory Duplicates

Laboratory sample matrix spikes and matrix spike duplicate analyses were performed with the sample batch. The acceptance criteria for the recovery of each analyte is typically 70 - 130%.

SMART Consulting and Tetra Tech 20 September 2014

The acceptance criteria for the relative percent difference (RPD) between the matrix spike/matrix spike duplicate is less than or equal to 20%.

Sample matrix spike and matrix spike duplicates met all acceptance criteria (70-130%) except for the following:

Bromodichloromethane, bromoform, carbon tetrachloride, chlorodibromomethane, 1,1-dichloroethane. The bromodichloromethane and chlorodibromomethane RPD for the matrix spike duplicate sample was outside the advisory limit. Since none of these constituents are project recognized COPCs and are not typically reported the results of the laboratory QC sample results outside of the advisory limit shall have no effect on the project or the project decision process.

Holding Times

The VOC samples are to be analyzed with fourteen days of collection. All of the VOC analyses for this project were performed within the fourteen-day holding time with the exception of the previously noted Duplicate (B14070391-014) and Field Blank (B14070391-015).

SAMPLE QUALIFICATION

There were no qualified analyte concentrations, the exception being toluene at 1.2 µg/L “J” flag estimated, that weren’t already qualified as “J” flag estimated by the lab or were not relevant to the COPCs for BVSL (i.e. bromodichloromethane, bromoform, carbon tetrachloride, chlorodibromomethane, and 1,1-dichloroethane) due to QC criteria outside the acceptance limits.

SMART Consulting and Tetra Tech 21 September 2014

5.0 REFERENCES

DEQ, 1999. Circular WQB-7, Montana Numeric Water Quality Standards, Montana Department of Environmental Quality. September.

DEQ, 2002. Record of Decision, Bitterroot Valley Sanitary Landfill, Montana Department of Environmental Quality. January.

Ecology and Environment, Inc. 1991. Final, Listing Site Inspection Report for the Bitterroot Valley Sanitary Landfill, Victor, Montana. Report issued to USEPA Region VIII.

Kerfoot, H. B. 1994. Journal of Air & Waste Management Association, Vol. 44. Landfill gas effects on groundwater samples at a municipal solid waste facility. November.

Maxim Technologies Inc. 1998c. Draft Groundwater Model Redesign and Calibration, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana. February.

Maxim Technologies Inc. 1999a. Draft, Construction Oversight Report Phase IIA Groundwater Remediation System Bitterroot Valley Sanitary Landfill, Ravalli County, Montana.

February.

Maxim Technologies Inc. 2002e. Amended Final Work Plan, Groundwater Monitoring, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana. December.

Tetra Tech, 2012. Bi-Annual Report June 2012 Groundwater Monitoring, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana, November.

Tetra Tech, 2014a. Bi-Annual Report July 2013 Groundwater Monitoring, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana, February.

Tetra Tech 2014b. Final Groundwater Monitoring Plan, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana, 2014 Amendment to the December 2002 Amended Final Work Plan, April.

U.S. Environmental Protection Agency. 1994a. U.S. EPA Contract Laboratory Program National Functional Guidelines for Inorganic Data Review. February.

U.S. Environmental Protection Agency. 1994b. U.S. EPA Contract Laboratory Program National Functional Guidelines for Organic Data Review. February.

APPENDIX A

HYDROSTRATIGRAPHIC TERMINOLOGY

A report titled Technical Memorandum, Groundwater Modeling, Bitterroot Valley Sanitary Landfill, Ravalli County, Montana issued in February 2002 describes the current conceptual model of groundwater flow and contaminant transport. This model is based on all available hydraulic and lithologic information collected to date. The following summarizes the hydrostratigraphic terminology developed for the BVSL. Figure A is a generalized cross-section showing each unit.

Unit A: Shallowest water-bearing unit, formerly referred to as the upper aquifer, includes shallow and deep portions.

Shallow Portion of Unit A: Hosting wells BRGW-2, -3, -8, -10, -30S, -32S, -33S, - 35S, -37S, -39S, -41S, -43S, -46S, -48S, -49S, -52S, -53S, -55S, -58S, -59S, -60S, -

81S, -85, -87S, -88S, -89S, BROW-02S, D-26, PW-02S, R-1, R-2, R-3S, R-5S, R-

7S, P-1, and P-2.

Deep Portion of Unit A: Hosting wells BRGW-1, -5, -9, -21, -31D, -34D, -36D, -38D, -40D, -42D, -50D, -51D, -54D, -82D, -83D, -86D, -90D, -91D, -92D, BROW-01D, D-

101, D-53, GW-18, R-4D, R-6D, R-8D, R-9D, R-10, SA-1, SA-2, SA-3, SA-4, SA-5,

SA-8, SA-9, SA-13, SA-14, SA-15, SA-16, SA-17, and P-3.

Unit B: Unit hosting well BR-GW-56DD, -61DD, -84D and D-39, formerly referred to as the lower aquifer.

Unit C: Unit hosting wells BR-GW-63DD, -65DD and -73DD.

Unit D: Unit hosting wells BR-GW-62DD, -64DD, -66DD through -72DD and -74DD through -80DD.

1st Aquitard: Separates shallow and deep portions of Unit A, formerly referred to as the…