B08_Solicitation_Attachment_6_2023_YNPwwtpMonitoringRept_0001.pdf

2023 Annual Groundwater and Surface Water Monitoring Report for Yellowstone National Park, Wyoming

March 2024

2022 ANNUAL GROUNDWATER AND SURFACE WATER MONITORING REPORT

FOR YELLOWSTONE NATIONAL PARK, WYOMING

Prepared for: National Park Service, IMR-Northern Rockies MABO ATTN: Molly Ohlen P.O. Box 168 Mammoth Supply Center 22 Stable St.

Yellowstone NP, WY 82190

Prepared by: WWC Engineering

1275 Maple Street, Suite F.

Helena, MT 59601

(406) 443-3962

Principal Authors: Scott Payne, PhD, P.G., Principle Scientist, Project Manager

Field Team: Jeremy Ferrell, Field Team Lead

SOLVING problems and DELIVERING value www.WWCengineering.com

Laramie Casper Sheridan Billings Helena

CIVIL/WATER RESOURCE ENGINEERING

¤ PUMPS AND PIPELINES

¤ SURFACE AND GROUNDWATER MODELING

¤ EARTH DAM DESIGN AND REHABILITATION

¤ WATER SUPPLY, TREATMENT AND DISTRIBUTION

¤ WASTEWATER TREATMENT AND DISPOSAL

¤ IRRIGATION SYSTEMS

¤ GPS AND CONVENTIONAL SURVEYING

¤ CIVIL ENGINEERING DESIGN, PLANS AND SPECIFICATIONS

¤ CONSTRUCTION ENGINEERING

¤ WATER RIGHTS

¤ COMPUTER-AIDED DESIGN AND DRAFTING (CADD)

¤ STORMWATER MANAGEMENT

¤ GEOTECHNICAL DRILLING AND SAMPLING

MINE SERVICES

¤ MINING AND RECLAMATION DESIGN AND PERMITTING

¤ RESERVOIR AND DAM DESIGN

¤ HAULROADS AND STREAM CROSSINGS

¤ HYDROLOGIC CONTROL PLANS

¤ ANNUAL REPORTS AND BOND CALCULATIONS

¤ NEPA COMPLIANCE DOCUMENTS

¤ 404 PERMITS

¤ BASELINE STUDIES

¤ GPS AND CONVENTIONAL SURVEYING

¤ DRILLING AND MONITORING SERVICES

¤ BLAST MONITORING AND REPORTING

¤ ABANDONED MINE LAND RECLAMATION

¤ RECLAIMED STREAM CHANNELS

¤ ASSESSMENT OF PROBABLE HYDROLOGIC CONSEQUENCES

¤ AVF ASSESSMENTS

TRANSPORTATION SERVICES

¤ RECONNAISSANCE REPORTS

¤ SURVEYS (RIGHT OF WAY, GROUND CONTROL,

CONSTRUCTION)

¤ BRIDGE HYDRAULICS, SCOUR ANALYSIS, STRUCTURE

SELECTION

¤ DESIGN OF URBAN STREETS, RURAL ROADWAYS

AND INTERSTATE RECONSTRUCTION

¤ STREETSCAPE ENHANCEMENTS

¤ UTILITY REPLACEMENT

¤ DRAINAGE DESIGN

¤ BICYCLE/PEDESTRIAN PATHWAYS

¤ PARKING FACILITIES

¤ CONSTRUCTION ADMINISTRATION

ENVIRONMENTAL SERVICES

¤ ENVIRONMENTAL COMPLIANCE AND BEST MANAGE-

MENT PRACTICES

¤ ENVIRONMENTAL IMPACT ANALYSIS AND REGULA-

TORY PERMITTING

¤ ENVIRONMENTAL SITE ASSESSMENTS

¤ GEOMORPHOLOGIC INVESTIGATIONS

¤ HYDROCARBON PRODUCT RECOVERY SYSTEM DE-

SIGN

¤ HYDROLOGIC AND WATER QUALITY MONITORING

¤ HAZARDOUS AND NON-HAZARDOUS WASTE MAN-

AGEMENT PLANNING

¤ SITE REMEDIATION PLANNING AND DESIGN

¤ SOIL AND GROUNDWATER CLEANUP PLANS

¤ UNDERGROUND STORAGE TANKS INVESTIGATION

AND REMOVAL PLANS

¤ NEPA COMPLIANCE DOCUMENTS

¤ ENVIRONMENTAL AUDITS

¤ WETLAND DELINEATION AND MITIGATION

¤ DRILLING

2023 Annual Groundwater Monitoring Report Yellowstone National Park March 11, 2024

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TABLE OF CONTENTS

1.0 Introduction

2.0 Field Sampling and Analysis

Monitoring Well Gauging

Monitoring Well Sampling

Surface Water Sampling

Laboratory Analysis

3.0 Madison Junction

Groundwater Flow

Specific Conductance

Nitrate/Nitrite (as N)

Chloride

Total Kjeldahl Nitrogen

4.0 Old Faithful

Groundwater Flow

Specific Conductance

Nitrate/Nitrite (as N)

Chloride

Total Kjeldahl Nitrogen

5.0 Grant Village

Groundwater Flow

Specific Conductance

Nitrate/Nitrite (as N)

Chloride

Total Kjeldahl Nitrogen

6.0 Fishing Bridge

Groundwater Flow

Specific Conductance

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Nitrate/Nitrite (as N)

Chloride

Total Kjeldahl Nitrogen

7.0 Data Quality Review

8.0 References

LIST OF FIGURES

Figure 1.1 Sampling Areas Yellowstone National Park Figure 2.1 Madison Junction Site Map Figure 2.2 Old Faithful Site Map Figure 2.3 Grant Village Site Map Figure 2.4 Fishing Bridge Site Map Figure 3.1 Madison Junction Groundwater Flow Figure 3.2 Madison Junction - Specific Conductance Figure 3.3 Madison Junction Nitrate/Nitrate (as N) Figure 3.4 Madison Junction Chloride Figure 3.5 Madison Junction Total Kjeldahl Nitrogen Figure 4.1 Old Faithful Groundwater Flow Figure 4.2 Old Faithful Specific Conductance Figure 4.3 Old Faithful Nitrate/Nitrate (as N) Figure 4.4 Old Faithful Chloride Figure 4.5 Old Faithful Total Kjeldahl Nitrogen Figure 5.1 Grant Village Groundwater Flow Figure 5.2 Grant Village Specific Conductance Figure 5.3 Grant Village Nitrate/Nitrate (as N) Figure 5.4 Grant Village Chloride Figure 5.5 Grant Village Total Kjeldahl Nitrogen Figure 6.1 Fishing Bridge Groundwater Flow Figure 6.2 Fishing Bridge Specific Conductance Figure 6.3 Fishing Bridge Nitrate/Nitrate (as N) Figure 6.4 Fishing Bridge Chloride Figure 6.5 Fishing Bridge Total Kjeldahl Nitrogen

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LIST OF TABLES

Table 2.1 2023 Laboratory Results Table 3.1 2023 Madison Junction Field and Laboratory Data Table 4.1 2023 Old Faithful Field and Laboratory Data Table 5.1 2023 Grant Village Field and Laboratory Data Table 6.1 2023 Fishing Bridge (FB) Field and Laboratory Data Table 7.1 QA/QC Sample Data Table 7.2 Nitrogen, Total Kjeldahl Nitrogen QA/QC Table 7.3 Nitrate/Nitrate (as N) QA/QC Table 7.4 Chloride QA/QC

LIST OF APPENDICES

Appendix A – Field Notes

Appendix B – Laboratory Report and Chain of Custody

Appendix C – Historical Data Tables

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1.0 INTRODUCTION

This report presents the 2023 results of groundwater and surface water sampling performed by WWC Engineering (WWC) on behalf of the National Park Service (NPS) in Yellowstone National Park (YNP). The work performed under this contract (Purchase Order #140P14234P0105) included groundwater monitoring services at four wastewater treatment plants (WWTPs) used by the park for the disposal and treatment of wastewater: Fishing Bridge, Grant Village, Old Faithful, and Madison Junction (collectively, hereafter, Site). Surface water samples were also collected at the four Sites. The Sites are all within YNP and depicted in Figure 1.1.

Figure 1.1 Sampling Areas Yellowstone National Park

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Aerial photography depicting the layout of the WWTPs are included as Figures 1.2, 1.3, 1.4, and 1.5. Four networks of groundwater monitoring wells are installed on and surrounding the sites. These wells have been historically used to monitor groundwater quality with respect to the park’s wastewater infrastructure. In addition, the sites are located proximal to streams, which were historically sampled to assess surface water quality at specific locations.

2.0 FIELD SAMPLING AND ANALYSIS

The NPS Field Sampling Plan proposed sampling from 44 monitoring wells and 14 surface water locations as depicted on Figures 2.2 through 2.5. WWC performed this sampling on September 11-14, 2023. The sampling was conducted in accordance with the NPS-approved Field Sampling Plan in WWC’s proposed scope of services letter proposal dated July 10, 2023.

Upon arrival, WWC performed a general site-wide inspection to document the physical nature of the site and locate the specific sampling points. The field crew consisted of Jeremiah Farrell and Robert Magann. Mr. Farrell was onsite for the duration of field activities serving as WWC’s Fieldwork Site Manager and Health and Safety Officer. Mr. Magann was onsite for the duration of the field activities and assisted Mr. Farrell in collecting all samples. The project work was performed under the direct supervision of Scott Payne, P.G., Project Manager for WWC’s activities. Mr. Payne is a Wyoming-licensed professional geologist with more than 35 years of experience in the environmental field. Sampling was performed in good weather conditions.

WWC was able to visually locate all wells to be sampled. Well site inspections were performed to note any significant issues which could potentially affect the sampling integrity. Inspections included an evaluation of the condition of each well pad, protective housing, lock, casing, and well cap (all if present). All the wells scheduled to be sampled were sampled, but a few had some minor damage, such as locks that would not open, and eventually after cutting and replacing the locks, the wells were sampled. No other accessibility issues or issues that compromised well integrity or ability to sample wells (e.g., bent casing) were observed. The findings of WWC’s well inspections are summarized in WWC’s field notes taken during the sampling event (Appendix A). It was also noted that spring FBS-4 at Fishing Bridge was dry.

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Figure 2.1 Madison Junction Site Map

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Figure 2.2 Old Faithful Site Map

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Figure 2.3 Grant Village Site Map

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Figure 2.4 Fishing Bridge Site Map

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MONITORING WELL GAUGING

Prior to sampling, depth to water was measured at each well. An electronic water level indicator was used to measure the depth to groundwater to the nearest 0.01 foot. However, due to a recording error on field forms by the field team, water level precision was measured to a 0.1-foot in most cases. This inadvertent recording error by the field team resulted in no significant differences in groundwater flow direction compared to earlier years. While the water level data are reported to 0.1 feet, the other well measurements, such as well measuring point elevation, are reported to 0.01-foot. The final calculated groundwater elevation is reported based on this accuracy (e.g., a hundredth of a foot). Water levels will be measured to 0.01-feet in 2024. Measurements were taken from a permanent mark on the well casing (if present) or the north side of the casing to ensure consistency between gauging events.

Groundwater elevation and stick-up heights are presented in Tables 3.1, 4.1, 5.1, and 6.1. Past survey grade well elevation is used to prepare a potentiometric surface map and determine groundwater flow direction by subtracting the current year water levels from the well measurement point elevations. Well stick-up heights in the Tables are from 2022 and were not measured in 2023.

MONITORING WELL SAMPLING

Following measurement of static water levels, the wells were purged using 1) non-dedicated galvanized tubing bailers (NPS provided); or, 2) dedicated disposable bailers (WWC provided).

A multi-parameter water quality meter was used to collect field measurements for temperature, pH, specific conductance, and dissolved oxygen. Purging was completed by lowering and lifting a decontaminated bailer (or disposable bailer). Ideally, the goal for purging is to remove three (3) well casing volumes while monitoring field parameters and ensuring field parameters stabilize once purging is complete. The scope of services also includes an option to terminate purging early.

In 2022 and 2023, purging was terminated early if there was a recharge problem and sediment started to enter the well. In these situations, if a well was slow to recharge and sediment started to enter it, at least one casing volume and stabilized field parameters was used to terminate purging and collect water quality samples. A decision to terminate early was a judgment call made in the field by the sampler based on the need to protect water sample integrity by limiting sediment entrainment. Prior to 2022, past contractors apparently waited longer to collect more purge water in problematic wells exhibiting slow recharge before collecting samples. Based on a comparison of past and current data, sampling prior to 2022 came closer to meeting the target volume of three well casings. However, the comparison also shows current data fall within a reasonable range and variability compared to the historic data (Appendix C). These comparisons support all data are representative of groundwater quality at the four NPS sites. It also may support that well purge volume may have limited or no significant impact on water quality. Nonetheless, the standard for purging a minimum of three well casing volumes remains the goal for future monitoring.

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To address the discrepancy between past, current, and future well purging, a clearly defined purge cutoff method is recommended. At minimum, future monitoring must include more detailed field documentation related to well purging described on well sampling forms supporting the decision to terminate purging early. Another solution is to recognize some of the wells are old construction with small diameter well casings, and that these wells are generally the ones with recharge issues. To this end, ideally the best option is to replace aging monitoring wells with new wells. New monitoring wells would be an improvement if constructed using larger diameter well casing, engineered well screens, and they are adequately developed so they produce higher flows and sediment free water. This option would ensure monitoring represents groundwater quality and purge volumes are met. Unfortunately, it is also prohibitively expensive to replace multiple wells. The most practical option is to prepare a detailed Sampling and Analysis Plan (SAP) that establishes the decision logic to terminate purging early in problematic wells and the associated documentation requirements. The 2023 field measurements and purge volumes are on the field sheets and included within Appendix A.

Once wells were purged, samples were collected into properly labeled laboratory-provided sample containers. To collect samples, the bailer is slowly and gently lowered into the well and allowed to fill, then retrieved, and the water was slowly drained into the lab provided sample containers. Sample times were recorded on the field sampling sheets, chain of custody forms, and on the sample labels. Samples were stored on ice and hand delivered under chain of custody protocols to Energy Laboratories in Casper, Wyoming as discussed below.

Dedicated sampling equipment was used when possible. Pre-cleaned and dedicated sampling materials/equipment was used to collect samples for laboratory analysis. After the samples were collected, any disposable, or one-time use equipment was placed in a plastic bag for disposal. Non-disposable sampling equipment (e.g., metal tubing, bailers, water level indicator, etc.) was decontaminated between each sampling site with distilled water and Alconox™ detergent and then rinsed with distilled water.

SURFACE WATER SAMPLING

Surface water samples were collected from moving water by wading into the water body. The sampling bottle opening was positioned upstream in the direction of flow to collect the sample and in a manner that did not disturb the bottom sediment but was depth-integrated by slowly lowering and raising the bottle until full. A multi-parameter water quality meter was used to collect field measurements for temperature, pH, specific conductance, and dissolved oxygen.

Surface water parameters were documented on the field sheets provided in Appendix A.

LABORATORY ANALYSIS

Energy Laboratories of Casper, WY provided analytical services for this project. Energy Laboratories exceeds rigorous criteria established by the U.S. EPA and multiple state regulatory agencies. In addition, the laboratory is an accredited institution by the National Environmental

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Laboratory Accreditation Program (NELAP) since 2001. The State of Wyoming does not have a laboratory certification program.

Surface water and groundwater samples were analyzed for nitrate/nitrite (as N), Kjeldahl nitrogen (TKN), and chloride. The following table describes the sample collection, preservation, and handling specifications.

Laboratory reports are provided in Appendix B. Individual tables for each site are provided in the following sections for Madison Junction, Old Faithful, Grant Village, and Fishing Bridge, respectively. Historical data tables are provided in Appendix C. Site specific discussions of the results are discussed in detail in the following sections.

Table 2.1 2023 Laboratory Results

Parameter Method Sample Matrix Preservation Container Type and

Minimum Volume

Holding Time and

Temperature

Nitrogen (nitrate + nitrite)

EPA 353.2 Water H2SO4 1-250 mL Plastic 28 days at 4°C

Total Kjeldahl Nitrogen EPA 351.2 Water H2SO4 1-250 mL Plastic 28 days at 4°C

Chloride EPA 300 Water Raw 1-250 mL Plastic 28 days at 4°C 1EPA Method 300 was used for analysis of nitrate + nitrite (as N) based on laboratory capabilities and sampling logistics (e.g ., preservation and hold time), in accordance with the NPS-approved Field Sampling Plan. ALS-Houston maintains National Environmental Laboratory Accreditation Program (NELAP) accreditation for methods utilized. See Section 7 for additional details.

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3.0 MADISON JUNCTION

Madison Junction sampling included a network of nine wells and two surface water samples, which were collected from the Madison River. Monitoring wells MW-11, MW-12, MW-13, and MW-14 were 2-inch diameter PVC wells with a protective steel cover. All 2-inch wells were noted as being in satisfactory condition, secured with NPS locks. The remaining monitoring wells were small diameter (e.g., 1.25” or 1.5”) with no protective cover around the steel above grade casing. All small diameter wells were noted as being in satisfactory condition. Table 3.1 summarizes field and laboratory data for this site.

GROUNDWATER FLOW

Based on the depth to groundwater measurements collected by WWC in September 2023, groundwater flow is generally to the south-southeast and towards the Madison River.

Groundwater elevation data is provided in Table 3.1. A potentiometric surface map is provided as Figure 3.1. Groundwater flow is consistent with that reported in the 2022 report. In 2023, groundwater elevations were highest near the WWTP, ranging from 6,793.47 in MJ-8 to a low of 6,786.85 in MJ-13, located downgradient of the WWTP.

SPECIFIC CONDUCTANCE

At Madison Junction, specific conductance in groundwater ranged from 171 µmhos/cm in well MJ-8 to 1,250 µmhos/cm in well MJ-13. Conductivity is lowest near the treatment ponds and increases with distance towards the Madison River. Overall, conductivities observed in 2023 are like data collected in 2022, but a little higher compared to 2021. All data were comparable and within the ranges of those reported in the record historically (Appendix C). Surface water ranged from 431µmhos/cm to 482 µmhos/cm. See Figure 3.2 for specific conductivity results.

NITRATE/NITRITE (AS N)

Nitrate/nitrite (as N) concentrations in groundwater ranged from values near the method detection limit at multiple sampling sites to 23.1 mg/l in well MJ-11 and 16.4 in well MJ-3.

Concentrations were lowest near the Madison River. Well MJ-11 and MJ-3 exceeded the health-based MCL and WDEQ groundwater screening levels of 10 mg/l for drinking water. Based on local land use, historic data, and location of impacted wells, elevated nitrate/nitrite concentrations may indicate incomplete or undersized wastewater treatment at Madison Junction. The presence of elevated nitrate/nitrite (as N) is consistent with previous sampling results, including very low levels detected in samples collected from the river sampling sites at

0.01 mg/l N. All other results are consistent with historical values at Madison Junction. See Figure 3.3 for nitrate/nitrite (as N) concentration results.

CHLORIDE

Chloride concentrations in groundwater ranged from 1 mg/l in well MJ-7 to 57 mg/l in MJ-10.

Concentrations were lowest near the treatment ponds and increased towards the Madison River.

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None were detected at concentrations above the Wyoming DEQ water quality standards of 250 mg/l. The Madison River sampling sites ranged from 56 mg/l to 62 mg/l at MJS-1 and MJS-2, respectively. These results are consistent with historical values at Madison Junction. See Figure

3.4 for chloride concentration results.

TOTAL KJELDAHL NITROGEN

Total Kjeldahl Nitrogen (TKN) groundwater concentrations ranged from values below the method detection limit at multiple sampling sites to 0.9 mg/l in well MJ-3. In addition, 1.1 mg/l TKN was detected in MJ-9. Madison River results were below the methods detection limit. There is no regulatory screening level standard for TKN. These results are consistent with historical values at Madison Junction. See Figure 3.5 for TKN concentration results.

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Table 3.1 2023 Madison Junction Field and Laboratory Data, Yellowstone National Park

Laboratory ID Location Project Name Ground

Elevation (ft)

Stick-Up (ft)

Casing Dia. (in)

SWL (ft)

SWL

Elevation (ft) pH Temp. (c) Specific Cond.

u mohs/cm

Dissolved Ox (mg/L)

Matrix Blank or

Duplicate Collection

Date Cl, mg/L, E300_0

NO3-T, mg/L, E353_2

Nitrogen, Kjeldahl, Total as N, mg/L, E351_2

Madison Junction (MJ)

C23090592-001 MJ_3 YNP 2023 Monitoring 6822.10 1.09 1.25 29.9 6793.29 6.12 14.31 306 5.63 GW 9/11/2023 21 16.4 0.9

C23090592-002 MJ_7 YNP 2023 Monitoring 6809.00 0.42 1.25 16.5 6792.92 6.62 13.44 113 5.44 GW 9/11/2023 1 2.68 0.8

C23090592-003 MJ_8 YNP 2023 Monitoring 6816.30 1.00 1.50 23.8 6793.47 6.48 14.12 171 4.62 GW 9/11/2023 2 0.08 <0.5

C23090592-004 MJ_9 YNP 2023 Monitoring 6797.10 0.55 1.50 8.9 6788.73 6.28 23.80 551 3.98 GW 9/11/2023 24 0.56 1.1

C23090592-005 MJ_10 YNP 2023 Monitoring 6809.70 0.75 1.50 21.9 6788.55 6.69 30.12 1210 3.13 GW 9/11/2023 57 0.18 <0.5

C23090592-006 MJ_11 YNP 2023 Monitoring 6817.48 1.40 2.00 26.1 6792.78 5.73 14.67 412 3.35 GW 9/11/2023 33 23.1 <0.5

C23090592-007 MJ_12 YNP 2023 Monitoring 6806.15 1.30 2.00 15.7 6791.75 6.44 14.66 137 5.08 GW 9/11/2023 3 1.64 <0.5

C23090592-008 MJ_13 YNP 2023 Monitoring 6810.97 1.80 2.00 25.9 6786.85 6.62 25.49 1250 2.67 GW 9/11/2023 56 0.13 <0.5

C23090592-012 MJ_13 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA GW Dup MJ-1 9/11/2023 58 0.13 <0.5

C23090592-009 MJ_14 YNP 2023 Monitoring 6803.29 2.00 2.00 12.7 6792.64 6.06 22.34 553 3.90 GW 9/14/2023 17 0.14 <0.5

C23090592-010 MJS-1 YNP 2023 Monitoring NA NA NA NA NA 7.53 20.46 431 6.02 SW 9/11/2023 56 0.01 <0.5

C23090592-011 MJS-2 YNP 2023 Monitoring NA NA NA NA NA 6.71 13.69 482 7.76 SW 9/11/2023 62 0.01 <0.5

SWL = Static Water Level TD = Total Depth

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Figure 3.1 Madison Junction Groundwater Flow

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Figure 3.2 Madison Junction - Specific Conductance

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Figure 3.3 Madison Junction Nitrate/Nitrate (as N)

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Figure 3.4 Madison Junction Chloride

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Figure 3.5 Madison Junction Total Kjeldahl Nitrogen

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4.0 OLD FAITHFUL

Old Faithful sampling included a network of five wells and two surface water samples, which are collected from Iron Spring Creek. Monitoring wells OF-10 and OF-11 were 2-inch diameter PVC wells with a protective steel cover and pad, in satisfactory condition, secured with NPS locks. The remaining wells were small diameter with steel casing above grade, secured with steel caps, no locks. All wells are noted as being in satisfactory condition. Well OF-5 was noted during sampling as having limited water within the water column, but WWC was able to collect a sample from the well. Table 4.1 summarizes all field and laboratory data for this site.

GROUNDWATER FLOW

Based on the depth to groundwater measurements collected by WWC in September 2023, groundwater flow is generally to the northwest in the WWTP area. Groundwater elevation data is provided in Table 4.1. A potentiometric surface map is provided as Figure 4.1. As denoted in Figure 4.1, the groundwater elevation in well OF-1 is anomalous (30 feet higher than other wells) and is close to 2021 water level data and previous years. This well may be completed in a different hydrogeologic unit or is associated with a locally perched groundwater system. If this well potentiometric datum is ignored, groundwater flow direction shifts to the north.

SPECIFIC CONDUCTANCE

The specific conductance in groundwater ranged from 114 µmhos/cm at OF-11 to 646 µmhos/cm in well OF-5. In 2023, conductivity was generally higher compared to 2022, but overall comparable with data in recent years past. Well OF-7B, which was noted as having about half the conductivity in 2023 compared to 2022. The cause for differences in specific conductance from year to year is unclear. Surface water specific conductance ranged from 143 µmhos/cm to 217 µmhos/cm. See Figure 4.2 for specific conductivity results.

NITRATE/NITRITE (AS N)

Nitrate/nitrite (as N) concentrations in groundwater ranged from values near the method detection limit at multiple sampling sites to 43.5 mg/l in well OF-5 and 30.8 mg/l in OF-10.

Concentrations were highest on both sides of the north end percolation ponds, with some levels trending higher than compared to 2021. Wells OF-5 and OF-7B trended opposite of each other in 2023 compared to 2022. Wells OF-5 and OF-10 exceeded the health-based MCL and WDEQ groundwater screening levels of 10 mg/l for drinking water. The presence of nitrate/nitrite in OF-7B and OF-11 are lower in 2023 compared to 2022. Based on the direction of groundwater flow, the nitrate/nitrite appears to be isolated to the east side and north side of the WWTP in 2023. One explanation for Nitrate/Nitrite variability in groundwater is seasonal loading and annual movement of high Nitrate/Nitrite concentrations following a northerly groundwater flow direction (see Section 4.1 above). Conceptually, Nitrate/Nitrite loading could be seasonal episodes vs. a continuous source. Nitrate/Nitrite variability would not be expected in the monitoring data if there was a steady or static release to groundwater. Based on local land use, historic data, and location of impacted wells over time, elevated nitrate/nitrite

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Surface water N ranged from 0.01 mg/l to 0.04 mg/l. See Figure 4.3 for nitrate/nitrite (as N) concentration results.

CHLORIDE

Chloride concentrations in groundwater ranged from 3 mg/l in well OF-1 to 50 mg/l in well OF-

7. Chloride was not detected at concentrations above regulatory screening levels in any of the samples. The Chloride concentrations are overall similar to 2022. Overall, it was found that concentrations fluctuate year to year, but are somewhat consistent with past results within the sampling record. Surface water chloride concentration ranged from 9 mg/l to 24 mg/l. See Figure 4.4 for chloride concentration results.

TOTAL KJELDAHL NITROGEN

Total Kjeldahl Nitrogen (TKN) concentrations in groundwater ranged from non-detect at multiple sampling sites to 1.1 mg/l in well OF-7B. These results are consistent with historical values at Old Faithful for most sites but were slightly less in 2023 compared to 2022 at wells OF-5 and OF-7B (Appendix C). Surface water quality was less than detection for TKN. See Figure

4.5 for TKN concentration results.

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Table 4.1 2023 Old Faithful Field and Laboratory Data, Yellowstone National Park

Laboratory ID Location Project Name Ground

Elevation (ft)

Stick-Up (ft)

Casing Dia. (in)

SWL (ft)

SWL

Elevation (ft) pH Temp. (c) Specific Cond.

u mohs/cm

Dissolved Ox (mg/L)

Matrix Blank or

Duplicate Collection

Date Cl, mg/L, E300_0

NO3-T, mg/L, E353_2

Nitrogen, Kjeldahl, Total as N, mg/L, E351_2

Old Fatithful (OF)

C23090591-001 OF_1 YNP 2023 Monitoring 7340.6 1 1.25 7.5 7334.10 6.42 12.62 146 7.59 GW 9/14/2023 3 0.05 <0.5

C23090591-002 OF_5 YNP 2023 Monitoring 7332.3 0.94 1.25 29.5 7303.74 6.15 14.52 646 4.51 GW 9/14/2023 41 43.6 1.0

C23090591-003 OF_7B YNP 2023 Monitoring 7312.6 0.71 1.25 10.7 7302.61 6.5 13.08 332 5.22 GW 9/14/2023 50 3.34 1.1

C23090591-004 OF_10 YNP 2023 Monitoring 7330.02 1.42 2 27.9 7303.54 6.14 14.6 531 2.99 GW 9/14/2023 47 30.8 <0.5

C23090591-005 OF_11 YNP 2023 Monitoring 7336.38 1.52 2 32.1 7305.80 6.19 18.29 114 5.77 GW 9/14/2023 4 0.25 <0.5

C23090591-006 OFS-1 YNP 2023 Monitoring NA NA NA NA NA 7.46 17.17 143 6.65 SW 9/14/2023 9 0.01 <0.5

C23090591-008 OFS-1 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA SW Dup OFS-3 9/14/2023 9 0.01 <0.5

C23090591-007 OFS-2 YNP 2023 Monitoring NA NA NA NA NA 7.4 17.36 217 7.38 SW 9/14/2023 24 0.04 <0.5

C23090591-009 OF-2 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA Aqueous Blank OF-2 9/14/2023 <1 <0.01 <0.5

SWL = Static Water Level TD = Total Depth

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Figure 4.1 Old Faithful Groundwater Flow

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Figure 4.2 Old Faithful Specific Conductance

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Figure 4.3 Old Faithful Nitrate/Nitrate (as N)

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Figure 4.4 Old Faithful Chloride

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Figure 4.5 Old Faithful Total Kjeldahl Nitrogen

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5.0 GRANT VILLAGE

Grant Village sampling included a network of 14 wells and 6 surface water sampling points.

WWC was able to sample all sites at Grant Village in 2023 and there were no sampling issues like those reported in 2021 that prevented sites from being sampled. In general, all wells were noted as being in satisfactory or functional condition, and no surface water sites were dry.

Table 5.1 summarizes all field and laboratory data for this site.

GROUNDWATER FLOW

Based on the depth to groundwater measurements collected by WWC in September 2023, groundwater flow is generally to the northwest and angling towards Yellowstone Lake in the treatment plant area. Groundwater elevation data are provided in Table 5.1. A potentiometric surface map is provided as Figure 5.1. West of the treatment plant, groundwater flow direction appears to be away from the lake. It should be noted that concentration data does not appear to match a northwest groundwater flow direction. Instead, concentration data appears to support a more northerly groundwater flow direction towards the lake from higher elevation land. The discrepancy between groundwater flow potentiometric data and concentration may be related to potential seasonal variation, deep and shallow aquifer data used to make one map, or issues related to the accuracy of well elevations.

Groundwater flow appears somewhat convoluted to the west of the WWTP as much lower groundwater elevations are reported in the wells to the west of the WWTP. It is noteworthy that the lower elevations all correlate to being within deeper wells (e.g., GV-17-130’ deep). It is unclear if the water bearing zone within the shallow wells around the WWTP is the same water bearing zone as the lower elevation water bearing zone in the wells to the west. For the purposes of contouring, all wells were included; however, other conceptual site model considerations may denote alternative flow pattern interpretations (shallow vs. deep).

SPECIFIC CONDUCTANCE

The specific conductance values in groundwater at Grant Village were all relatively low to moderate, and generally consistent with those reported historically ranging from 34 µmhos/cm to 423 µmhos/cm. GV-11 and GV-15 were approximately 424 µmhos/cm and 254 µmhos/cm, respectively, which is higher than the values reported in 2021 and like 2022, but well within the ranges reported historically through the 2000’s. Conductivity in surface water ranged from 24 µmhos/cm to 101 µmhos/cm. See Figure 5.2 for specific conductivity results.

NITRATE/NITRITE (AS N)

Nitrate/nitrite (as N) concentrations in groundwater ranged from values below the method detection limits at multiple sampling sites to 24 mg/l in well GV-11. Wells GV-9, GV-11, and GV-15 all exceeded the health-based MCL and WDEQ groundwater screening levels of 10 mg/l for drinking water. GV-4 was close at 9.5 mg/l. The presence of nitrate/nitrite (as N) in these wells is consistent with previous sampling results and in general, elevated nitrate/nitrate is

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Page | 27 present in 2023 and documented in the historic record (Appendix C). Based on local land use, historic data, and location of impacted wells over time, elevated nitrate/nitrite concentrations may indicate incomplete or undersized wastewater treatment at Grant Village. Surface water ranged from 0.01 to less than the detection limit for N. See Figure 5.3 for nitrate/nitrite (as N) concentration results.

CHLORIDE

Chloride concentrations in groundwater ranged from less than the method detection limit at multiple sampling sites to 31 mg/l in well GV-11. None of the results approached the regulatory level of 250 mg/l. These results are consistent with historical values at Grant Village. Surface water ranged from <1 mg/l to 5 mg/l. See Figure 5.4 for chloride concentration results.

TOTAL KJELDAHL NITROGEN

Total Kjeldahl Nitrogen (TKN) concentrations in groundwater ranged from values below the method detection limits at multiple sampling sites to 3.2 mg/l in well GV-6. A value of 1.2 mg/l is noted at surface water sampling site GVS-5, similar to historic results, but well above the concentration in Yellowstone Lake. Total kjeldahl nitrogen at GV-1 and GV-10 are lower than the historic concentrations, but overall, the results are consistent with historical values at Grant Village (Appendix C). Surface water was <0.5 mg/l at all sites except GVS-6 with a concentration of 1.2 mg/l. See Figure 5.5 for TKN concentration results.

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Table 5.1 2023 Grant Village Field and Laboratory Data, Yellowstone National Park

Laboratory ID Location Project Name Ground

Elevation (ft)

Stick-Up (ft)

Casing Dia. (in)

SWL (ft)

SWL

Elevation (ft) pH Temp. (c) Specific Cond.

u mohs/cm

Dissolved Ox (mg/L)

Matrix Blank or

Duplicate Collection

Date Cl, mg/L, E300_0

NO3-T, mg/L, E353_2

Nitrogen, Kjeldahl, Total as N, mg/L, E351_2

Grant Villiage (GV) C23090579-001 GV_1 YNP 2023 Monitoring 7773.80 1.71 1.25 6.9 7768.61 7.13 8.04 229 6.03 GW 9/13/2023 <1 <0.01 1.8

C23090579-002 GV_2 YNP 2023 Monitoring 7784.00 0.83 1.25 30.0 7754.83 6.07 7.66 163 11.21 GW 9/13/2023 13 5.96 1.7

C23090579-003 GV_3A YNP 2023 Monitoring 7788.60 1.33 1.25 24.9 7765.03 6.61 7.67 47 10.03 GW 9/13/2023 1 0.14 <0.5

C23090579-004 GV_4 YNP 2023 Monitoring 7794.90 0.97 1.25 36.7 7759.17 6.38 9.88 208 9.21 GW 9/13/2023 16 9.5 1.1

C23090579-005 GV_6 YNP 2023 Monitoring 7801.30 0.91 1.25 16.1 7786.11 7.31 6.64 125 12.56 GW 9/13/2023 <1 0.32 3.2

C23090579-006 GV_9 YNP 2023 Monitoring 7820.60 0.50 1.25 43.2 7777.90 6.35 8.93 231 9.71 GW 9/13/2023 13 14.5 1.9

C23090579-007 GV_10 YNP 2023 Monitoring 7816.30 0.65 1.25 21.0 7795.95 7.47 6.58 148 7.88 GW 9/13/2023 <1 0.44 1.3

C23090579-008 GV_10A YNP 2023 Monitoring 7816.70 1.33 1.25 10.0 7808.03 6.54 7.96 34 10.62 GW 9/13/2023 <1 0.03 1.2

C23090579-009 GV_11 YNP 2023 Monitoring 7830.10 0.75 1.50 83.6 7747.25 6.21 10.27 423 8.68 GW 9/13/2023 31 24.0 1.0

C23090579-010 GV_12 YNP 2023 Monitoring 7792.50 1.17 1.50 58.7 7734.97 7.06 8.18 62 9.96 GW 9/13/2023 <1 0.02 1.9

C23090579-011 GV_13 YNP 2023 Monitoring 7801.00 0.83 1.50 81.0 7720.83 6.12 12.59 100 8.41 GW 9/13/2023 <1 0.06 <0.5

C23090579-012 GV_14A YNP 2023 Monitoring 7741.46 1.16 2.00 11.9 7730.72 5.90 8.42 67 7.03 GW 9/13/2023 <1 <0.01 0.6

C23090579-013 GV_15 YNP 2023 Monitoring 7772.19 1.65 2.00 28.3 7745.54 5.50 9.00 254 7.95 GW 9/13/2023 26 10.4 0.6

C23090579-014 GV_17 YNP 2023 Monitoring 7839.38 1.73 2.00 116.8 7724.31 6.93 10.49 121 8.73 GW 9/13/2023 4 0.53 <0.5

C23090579-021 GV_17 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA GW Dup GV-7 9/13/2023 4 0.53 <0.5

C23090579-015 GVS-1 YNP 2023 Monitoring NA NA NA NA NA 6.77 12.21 97 8.93 SW 9/13/2023 5 <0.01 <0.5

C23090579-016 GVS-2 YNP 2023 Monitoring NA NA NA NA NA 6.96 8.76 101 10.42 SW 9/13/2023 5 <0.01 <0.5

C23090579-017 GVS-3 YNP 2023 Monitoring NA NA NA NA NA 7.87 14.54 96 8.75 SW 9/13/2023 5 <0.01 <0.5

C23090579-018 GVS-4 YNP 2023 Monitoring NA NA NA NA NA 7.45 13.18 95 8.97 SW 9/13/2023 5 0.01 <0.5

C23090579-019 GVS-5 YNP 2023 Monitoring NA NA NA NA NA 6.63 14.92 24 7.51 SW 9/13/2023 <1 <0.01 1.2

C23090579-020 GVS-6 YNP 2023 Monitoring NA NA NA NA NA 7.31 10.82 60 7.89 SW 9/13/2023 <1 <0.01 <0.5

*SWL = Static Water Level **TD = Total Depth

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Figure 5.1 Grant Village Groundwater Flow

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Figure 5.2 Grant Village Specific Conductance

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Figure 5.3 Grant Village Nitrate/Nitrate (as N)

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Figure 5.4 Grant Village Chloride

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Figure 5.5 Grant Village Total Kjeldahl Nitrogen

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6.0 FISHING BRIDGE

Fishing Bridge sampling included a network of 16 wells and 4 surface water sampling points.

One surface water location, FBS-4 ST was dry in 2023 and has been dry since 2011. All the wells at Fishing Bridge were noted as being in satisfactory condition and samples were collected from all the wells. Table 6.1 summarizes all field and laboratory data for this site.

GROUNDWATER FLOW

Based on the depth to groundwater measurements collected by WWC in September 2023, groundwater flow in the WWTP area is generally to the southwest towards the Yellowstone River but is locally variable. Groundwater elevation data are provided in Table 6.1. A potentiometric surface map is provided as Figure 6.1. Groundwater elevation data show a westerly flow direction in the FB-17 well location area, also towards the Yellowstone River.

SPECIFIC CONDUCTANCE

The specific conductance in groundwater ranged from 69 µmhos/cm in well FB-17A to 387 µmhos/cm in well FB-2. The conductivity was slightly higher in monitoring wells located proximal to the treatment ponds and generally lower in downgradient wells (e.g., FB-14A and FB-17A). This trend is consistent with that observed historically. The concentrations observed overall were all relatively low. There is some difference in conductivity observed between upgradient well FB-7 and downgradient wells, indicating that the WWTP impact on water quality is negligible but slightly higher near the ponds. The conductivities were generally consistent with years past.

Some of the wells, particularly around the WWTP reported slightly higher conductance than in 2021 but are within the ranges on record with consistent site wide trends in 2022 and 2023.

Surface water specific conductance ranged from 105 to 114 µmhos/cm. See Figure 6.2 for specific conductivity results.

NITRATE/NITRITE (AS N)

Nitrate/nitrite (as N) concentrations in groundwater ranged from values below the method detection limits at sampling sites, and especially in the Yellowstone River to 8.84 mg/l in well FB-18 and 7.32 mg/l in well FB-4. None of the wells in 2023 exceeded the health-based MCL and WDEQ groundwater screening levels of 10 mg/l for drinking water, which represents a decrease in N concentrations compared to 2022. FB-4 is located proximal to the WWTP and has a lower nitrate/nitrite concentration in 2023 compared to 2022. An overall decrease in nitrate/nitrite concentration observed from 2021 through 2023 may support a downward concentration trend near the WWTP. More monitoring is required to confirm a trend, and for now the 2023 results are considered within the range reported historic concentrations. All other wells were below the regulatory threshold. See Figure 6.3 for nitrate/nitrite (as N) concentration results. Surface water N was less than the detection limit.

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CHLORIDE

Chloride concentrations in groundwater ranged from <1mg/l in well FB-7 to 38 mg/l in well FB-

4. None were detected at concentrations near or approaching the regulatory level of 250 mg/L.

These results are consistent with historical values at Fishing Bridge. See Figure 6.4 for chloride concentration results. Surface water chloride concentration ranged from 5 mg/l to 6 mg/l.

TOTAL KJELDAHL NITROGEN

Total Kjeldahl Nitrogen (TKN) concentrations in groundwater ranged from less than the method detection limit at multiple sampling sites to 6.2 mg/l in well FB-13. These results are consistent with historical values at the Fishing Bridge. Surface water TKN was less than the detection limit. See Figure 6.5 for TKN concentration results.

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Table 6.1 2023 Fishing Bridge (FB) Field and Laboratory Data, Yellowstone National Park

Laboratory ID Location Project Name Ground

Elevation (ft)

Stick-Up (ft)

Casing Dia. (in)

SWL (ft)

SWL

Elevation (ft) pH Temp. (c) Specific Cond.

u mohs/cm

Dissolved Ox (mg/L)

Matrix Blank or

Duplicate Collection

Date Cl, mg/L, E300_0

NO3-T, mg/L, E353_2

Nitrogen, Kjeldahl, Total as N, mg/L, E351_2

Fishing Bridge (FB) C23090580-001 FB_1 YNP 2023 Monitoring 7764.50 0.47 1.25 16.8 7748.17 6.69 8.3 324 4.33 GW 9/11/2023 21 5.03 1.4

C23090580-002 FB_2 YNP 2023 Monitoring 7762.20 1.73 1.25 13.5 7750.43 6.88 8.26 387 6.11 GW 9/12/2023 24 7.32 1.1

C23090580-003 FB_3 YNP 2023 Monitoring 7775.30 0.58 1.25 26.9 7748.98 6.47 10.45 317 5.87 GW 9/12/2023 27 2.71 1.8

C23090580-004 FB_4 YNP 2023 Monitoring 7774.80 1.04 1.25 21.3 7754.59 6.44 10.77 310 6.34 GW 9/12/2023 38 4.80 1.2

C23090580-005 FB_7 YNP 2023 Monitoring 7783.00 1.15 1.25 26.8 7757.40 6.91 6.13 88 11.07 GW 9/12/2023 <1 0.16 <0.5

C23090580-006 FB_9 YNP 2023 Monitoring 7743.20 0.35 1.25 7.8 7735.75 6.77 5.84 308 7.89 GW 9/12/2023 17 4.33 0.8

C23090580-007 FB_10 YNP 2023 Monitoring 7764.70 0.92 1.25 9.8 7755.87 6.61 6.59 150 9.79 GW 9/12/2023 10 1.36 1.0

C23090580-008 FB_11 YNP 2023 Monitoring 7761.40 0.67 1.25 12.5 7749.57 6.73 10.08 358 4.44 GW 9/11/2023 26 2.04 0.9

C23090580-009 FB_12 YNP 2023 Monitoring 7755.80 0.67 1.25 19.2 7737.27 6.55 7.94 232 5.08 GW 9/11/2023 15 3.61 1.4

C23090580-010 FB_13 YNP 2023 Monitoring 7738.80 0.88 1.00 4.1 7735.58 6.85 7.67 212 5.37 GW 9/12/2023 10 0.37 6.2

C23090580-011 FB_14A YNP 2023 Monitoring 7760.30 0.42 1.50 12.4 7748.32 7.67 6.27 85 9.92 GW 9/12/2023 2 0.18 0.6

C23090580-012 FB_15A YNP 2023 Monitoring 7753.40 1.75 2.00 14.9 7740.25 6.85 4.78 79 10.32 GW 9/12/2023 1 0.17 <0.5

C23090580-020 FB-15A YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA GW FB-05 9/12/2023 1 0.17 <0.5

C23090580-013 FB_16 YNP 2023 Monitoring 7767.70 0.58 1.50 11.0 7757.28 6.72 6.13 206 9.91 GW 9/12/2023 14 3.64 0.8

C23090580-014 FB_17A YNP 2023 Monitoring 7757.00 2.25 2.00 15.2 7744.05 6.93 9.9 69 10.05 GW 9/14/2023 1 0.21 <0.5

C23090580-015 FB_18 YNP 2023 Monitoring 7773.17 1.54 2.00 7.9 7766.81 6.5 6.17 255 6.19 GW 9/12/2023 19 8.84 0.9

C23090580-016 FB_19 YNP 2023 Monitoring 7741.58 1.71 2.00 4.5 7738.79 7.62 6.09 107 4.38 GW 9/11/2023 3 <0.01 0.5

C23090580-017 FBS-1 YNP 2023 Monitoring NA NA NA NA NA 8.92 16.08 113 9.84 SW 9/12/2023 6 <0.01 <0.5

C23090580-018 FBS-2 YNP 2023 Monitoring NA NA NA NA NA 8.33 15.82 114 9.96 SW 9/12/2023 5 <0.01 <0.5

C23090580-019 FBS-3 YNP 2023 Monitoring NA NA NA NA NA 6.46 12.53 97 9.91 SW 9/12/2023 5 <0.01 <0.5

NA FBS-4 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA Dry NA NA NA NA

C23090580-021 FF2 YNP 2023 Monitoring NA NA NA NA NA NA NA NA NA Aqueous Blank FF2 9/12/2023 <1 <0.01 <0.5

*SWL = Static Water Level **TD = Total Depth

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Figure 6.1 Fishing Bridge Groundwater Flow

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Figure 6.2 Fishing Bridge Specific Conductance

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Figure 6.3 Fishing Bridge Nitrate/Nitrate (as N)

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Figure 6.4 Fishing Bridge Chloride

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Figure 6.5 Fishing Bridge Total Kjeldahl Nitrogen

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7.0 DATA QUALITY REVIEW

All data generated as part of the September 2023 sampling event were subjected to data review consistent with U.S. EPA National Functional Guidelines for Inorganic Data Review. QC Batch Reports are provided in Appendix B. A summary of quality control findings is summarized below and is intended to serve as a high-level summary for the data validation that WWC performed with the sole objective of ensuring that the data are usable for their intended purposes.

Energy Laboratories, Inc. of Casper, WY (hereafter, “laboratory”) provided the analytical services for the project. The laboratory Quality Assurance Plan (QAP) is available online here:

https://www.energylab.com/wp-content/uploads/2012/04/Billings-QA-Manual- 2015_final1.pdf. The laboratory performed analytical data reduction before releasing the final data package consistent with the laboratory’s QAP.

Upon receipt of the final laboratory data package, the WWC Quality Assurance/Quality Control (QA/QC) officer, Scott Payne, conducted an evaluation of data reduction and reporting by the laboratory. These activities included an evaluation of the data sheets and QA/QC results. All analyses were checked for completeness and accuracy. Any discrepancies identified during the data reduction and reporting review are reported herein.

The laboratory qualified the data based on the laboratory’s Quality Assurance Plan and method-specific Quality Control (QC) criteria. Qualified results are depicted in figures and denoted accordingly as described in the laboratory report.

Groundwater samples were analyzed in accordance with the methods specified in the NPS-approved Field Sampling Plan (WWC, 2022). EPA Method 300 was used for analysis of nitrate + nitrite (as N) based on laboratory capabilities and sampling logistics. Energy Laboratory maintains National Environmental Laboratory Accreditation Program (NELAP) accreditation.

WWC collected the following field Quality Assurance (QA) Quality Control (QC) samples as required in the original proposal. See QC samples notated in Tables 3.1, 4.1, 5.1, and 6.1 in dark grey highlight.

Table 7.1 QA/QC Sample Data Sample Type Purpose Frequency

Field blank Evaluate laboratory accuracy and precision

One blank per 30 investigative samples (2 collected for the project).

Field duplicate Evaluate sampling and laboratory precision

One field duplicate per 15 investigative samples (4 collected for the project) https://www.energylab.com/wp-content/uploads/2012/04/Billings-QA-Manual-2015_final1.pdf https://www.energylab.com/wp-content/uploads/2012/04/Billings-QA-Manual-2015_final1.pdf

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Samples were analyzed for Total Kjeldahl Nitrogen by EPA 351.2

Holding Times: All samples were analyzed within the method-specified holding time of 28 days.

Preservation: All samples were preserved in the field with sulfuric acid to achieve a pH <2.

Samples were then placed in an iced cooler and shipped to the laboratory. The cooler was received at the laboratory within temperature specifications (≤ 6ºC).

Method Blank: One method blank was analyzed for each sample batch. No analytes were present in the method blanks.

Laboratory Control Sample: One LCS was collected for each sample batch. Percent recovery within the method control limits of 90%-110%.

Duplicate Sample: Duplicate samples were collected from FB-15A, OFS-1, MJ-13 and GV-17. A summary of the primary and duplicate samples and relative percent difference (RPD) calculations is provided in the table below. RPDs calculated are within acceptable limits (20%), and in this case exceptional. Ideally, duplicate water samples will have RPDs less than 20% and soil samples less than 30%, but if RPDs exceed this, it does not necessarily mean the data are of poor quality. There are many reasons for high RPDs, including sample heterogeneity or samples with high concentrations. RPD results should be evaluated within the scope of the entire sampling/analytical program and considering the data quality objectives for total Kjeldahl nitrogen. Total Kjeldahl nitrogen data may be used for its intended purposes.

Table 7.2 Nitrogen, Total Kjeldahl Nitrogen QA/AC Location Primary Result Duplicate Result RPD

FB-15A <0.5 <0.5 0%

OFS-1 <0.5 <0.5 0%

MJ_13 <0.5 <0.5 0%

GV-17 <0.5 <0.5 0%

Spike Sample Results: MS/MSD samples were analyzed for each sample batch. Matrix spike percent recoveries were within the method specified acceptance criteria of 90%-110%. The RPD between MS and MSD results were within method specified acceptance criteria (10%) in most, but not all cases. Calibration of the testing equipment corrected all discrepancies.

Samples were analyzed for nitrate/nitrite by EPA Method 353.2

Holding Times: All samples were analyzed within the method-specified holding time of 28 days.

Preservation: Samples were collected into laboratory-provided neat containers and placed in an iced cooler and shipped to the laboratory. The cooler was received at the laboratory within temperature specifications (≤ 6ºC).

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Method Blank: One method blank was analyzed for each sample batch. No analytes were present in the method blanks.

Laboratory Control Sample: One LCS was collected for each sample batch. Percent recovery was within the method control limits of 90%- 110%.

Duplicate Sample: Duplicate samples were collected from FB-15A, OFS-1, MJ-13 and GV-17. A summary of the primary and duplicate samples and RPD calculations are provided in the table below. All RPDs were within acceptable limits and are exceptional.

Table 7.3 Nitrate/Nitrate (as N) QA/QC Location Primary Result Duplicate Result RPD

FB-15A 0.17 0.17 0%

OFS-1 0.01 0.01 0%

MJ_13 0.13 0.13 0%

GV-17 0.53 0.53 0%

percent recoveries were within the method specified acceptance criteria of 90%-110%. The RPD between MS and MSD results were within method specified acceptance criteria (10%) in most, but not all cases. Calibration of the testing equipment corrected all discrepancies.

Samples were analyzed for chloride by EPA Method 300.0

Holding Times: All samples were analyzed within the method-specified holding time of 28 days.

Preservation: Samples were collected into laboratory-provided neat containers and placed in an iced cooler and shipped to the laboratory. The cooler was received at the laboratory within temperature specifications (≤ 6ºC).

Method Blank: One method blank was analyzed for each sample batch. No analytes were present in the method blanks.

Laboratory Control Sample: One LCS was collected for each sample batch. Percent recovery was within the method control limits of 90%- 110%.

Duplicate Sample: Duplicate samples were collected from FB-11, FB-16, OFS-1 and GV-13. A summary of the primary and duplicate samples and RPD calculations are provided in the table below. All RPDs were within acceptable limits, and three of the four are exceptional.

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Table 7.4 Chloride QA/QC Location Primary Result Duplicate Result RPD

FB-15A 1 1 0%

OFS-1 9 9 0%

MJ_13 56 58 3.51%

GV-17 4 4 0%

percent recoveries were within the method specified acceptance criteria of 90%-110. The RPD between MS and MSD results were within method specified acceptance criteria (20%) in most, but not all cases. Calibration of the testing equipment corrected all discrepancies.

Field Blanks Analytical Results

Two blind field blank samples (Table 1) were prepared using distilled water and analyzed by Energy Laboratories. Both blank samples showed no contaminants and are considered acceptable.

8.0 REFERENCES

Cox, E.R. 1979. Preliminary Study of Wastewater Movement in Yellowstone National Park, Wyoming, October 1976 through September 1977. USGS Open File Report 79-684. 59p.

WWC, 2023, Proposed Sampling Plan for Yellowstone National Park, prepared by WWC on behalf of the National Park Service, September.

YNP, 2023, Statement of Work, prepared by National Park Service.

APPENDIX A

FIELD NOTES

APPENDIX B

LABORATORY REPORT AND CHAIN OF CUSTODY

Chain of Custodies

EN:RGY cm· Chain of Custody &…