A2+-+2023+Risk+Assessment.pdf

4501 Coleman Street Suite 103, Bismarck, ND 58503

Florida • Colorado • North Dakota • New Jersey • Texas • Pennsylvania • New York

July 14, 2023

Mr. Derek Kannenberg North Dakota Department of Environmental Quality Hazardous Waste Program Manager 4201 Normandy Street Bismarck, North Dakota 58503-1324

RE: North Dakota Risk-Based Corrective Action (NDRBCA) Tier 1 Report Former M & H Gas Station Wahpeton, North Dakota Oil Field Environmental Incident Summary No. 20170725100317 GPS Coordinates: 48.472710710, -102.911258438 Township 132 North, Range 47 West, Southwest Quarter of the Northwest Quarter of Section 8 Richland County, North Dakota

Dear Mr. Kannenberg:

This NDRBCA Tier 1 Report (Report) was prepared for the North Dakota Department of Environmental Quality (NDDEQ), to document subsurface conditions at the former M&H gas station in Wahpeton, North Dakota (Site). The approximately 0.23-acre area is located at the southwest corner of 7th Street North and Dakota Avenue in Wahpeton, North Dakota (Figure 1). Land in the vicinity of the Site is primarily utilized for commercial and some industrial business operations.

RECOMMENDATIONS

Based on the results of the Tier 1 evaluation, petroleum impacts on-site do not pose a risk to any sensitive receptors. The City of Wahpeton seeks closure under Tier 1 for the site.

Sincerely, EARTH SYSTEMS, INC.

Tim Adair, P.G. C. HG Senior Hydrogeologist

Cc: Derek Kannenberg, NDDEQ

NORTH DAKOTA RISK-BASED CORRECTIVE ACTION (NDRBCA)

TIER 1 REPORT FORMS

Site name:

Facility ID number (if any):

Site address:

Date site discovered:

Responsible Party Information:

Business name:

Contact person name:

Contact person address:

Contact person Phone No.:

Contact person Email ID:

Qualified consultant information:

Name:

Company name:

Address:

Phone No. & Email ID:

Date form completed:

Form completed by:

North Dakota Risk-Based Corrective Action (NDRBCA) Tier 1 Report Forms

(NDRBCA Draft Tier 1 Report Forms, January 2023)

Former M & H Gas Station

LUST ID 1464

701 Dakota Avenue, Wahpeton, ND 58075

10/25/2006

T. Adair & I. Akpakpan

CITY OF WAHPETON

CITY OF WAHPETON

PO BOX 490, WAHPETON ND 58074-0490

Tim Adair Earth Systems 4501 Coleman Street, Bismarck, ND 58503

701.934.1534 & tadair@earthsys.net 7/14/2023

Form No. Description No. of Pages

1. Executive Summary X

2. Site Information X

3. Site Discovery X

4. Underground Storage Tank Types X

5. Land Use (On-Site and Off-Site) X

6. Chronology of Events X

7. Comprehensive Summary of Data X

8. Light Non-Aqueous Phase Liquid (LNAPL)

9. Site Stratigraphy and Hydrogeology X

10. Geotechnical Parameters X

11. X

12. Exposure Model X X X

Off-Site Resident (Current and Reasonably Anticipated Future Conditions) X X X

Summary of Exposure Model (Complete Routes of Exposure Highlighted) X

13. Consideration of Groundwater Protection Pathway X

14. Consideration of Surface Water Protection Pathway

15. Comparison of Representative Site Concentrations with Tier 1 RBSLs On-Site Resident (Current Conditions) On-Site Commercial/Industrial Worker (Current Conditions) X

On-Site Construction Worker (Current Conditions) X

On-Site Resident (Reasonably Anticipated Future Conditions) X

On-Site Construction Worker (Reasonably Anticipated Future Conditions) X

Off-Site Resident (Current Conditions) Off-Site Commercial/Industrial Worker (Current Conditions) X Off-Site Resident (Reasonably Anticipated Future Conditions)

X Summary of Exceedances X

16. X

17.

18(a). Conclusion and Recommendation (On-Site) X

18(b). Conclusion and Recommendation (Off-Site) 18(c). Ecological Risk Evaluation X

Description No. of Pages

19(a). Corrective Action (Soil Excavation) 19(b). Corrective Action (Pump and Treat) 19(c). Corrective Action (Air Sparge Soil Vapor Extraction) 19(d). Corrective Action (Soil Vapor Extraction By Vacuum Truck)

Groundwater to Surface Water Protection Pathway

NDRBCA REPORT

TABLE OF CONTENTS

SITE INFORMATION AND TIER 1 FORMS (Continued)

In report?

CONCEPTUAL SITE MODEL

No. In report?

EXPOSURE MODEL

On-Site Resident (Current and Reasonably Anticipated Future Conditions) On-Site Commercial/Industrial Worker (Current and Reasonably Anticipated Future Conditions)

Off-Site Commercial/Industrial Worker (Current and Reasonably Anticipated Future Conditions)

TIER 1 EVALUATION

On-Site Commercial/Industrial Worker (Reasonably Anticipated Future Conditions)

Off-Site Commercial/Industrial Worker (Reasonably Anticipated Future Conditions)

Comparison of Representative Site Concentrations with Tier 1 Groundwater Protection Target Concentrations Comparison of Representative Site Concentrations with Tier 1 Surface Water Protection Target Concentrations

TABLE OF CONTENTS

SITE INFORMATION AND TIER 1 FORMS (Continued)

On-Site Construction Worker (Current and Reasonably Anticipated Future Conditions)

Off-Site Construction Worker (Current and Reasonably Anticipated Future Conditions)

NDRBCA REPORT

RISK MANAGEMENT PLAN

19(e). Corrective Action (LNAPL Removal) 19(f). Corrective Action (Enhanced Monitored Natural Attenuation) 19(g). Dual/Multi Phase Extraction 19(h). Corrective Action (Environmental Covenant)

20. References

1 Comprehensive Soil Analytical Data for Primary Chemicals X

Comprehensive Soil Analytical Data for Secondary Chemicals X

Soil Analytical Data for Total Petroleum Hydrocarbons X

Field PID Readings Measured During Soil Boring Installation1

2. Monitoring Well Construction Details & Gauging Data Light Non-Aqueous Phase Liquid (LNAPL) Recovery

3. Comprehensive Groundwater Analytical Data for Primary Chemicals X

Comprehensive Groundwater Analytical Data for Secondary Chemicals X

Comprehensive Soil Vapor Analytical Data for Primary Chemicals Comprehensive Soil Vapor Analytical Data for Secondary Chemicals Comprehensive Subslab Vapor Analytical Data for Primary Chemicals Comprehensive Subslab Vapor Analytical Data for Secondary Chemicals Comprehensive Indoor Air Analytical Data for Primary Chemicals Comprehensive Indoor Air Analytical Data for Secondary Chemicals

Description

1. Site Location Map Figure No. X

2. Site Map Showing Site Boundaries and Past and Present Site Features Figure No. X

Land Use Map (Radius of 1,000 feet) Figure No. X Site Map Showing Buildings within 1,000 ft of source Figure No. X Site Map Showing Location and Depths of On-Site and Off-Site Subsurface Utilities Figure No. X

3.

Site Map Showing Soil Boring and Monitoring Well Locations (including drinking water wells onsite) Figure No. X

Figure Showing Suspected Source(s) of LNAPL Figure No.

4. Figures Showing Soil Stratigraphy and Cross-Sections Figure No. X

Figure Showing Groundwater Gradients or Water Level Contour Map

5. Figure Showing Soil Concentrations or Contour Map Figure No. X

6. Figure Showing Groundwater Concentrations or Contour Map Figure No. X

Figure Showing Areas of Excavation Figure No.

Figure Showing Location of Post Excavation Soil Samples Figure No.

Figure Showing Location of Pumping Wells Figure No.

Figure Showing Location of Vapor Extraction Points Figure No.

Figure Showing Location of Injection Points for Enhanced Natural Attenuation Figure No.

Figure Showing Location of Dual Phase Extraction Wells Figure No.

Site Map Showing the Surface Water Feature including Storm Water Sewer Figure No.

Figure for Cross Section Showing the Groundwater Table and Bottom of Surface Water Feature Figure No.

7.

Figure showing the Location(s) of the Soil source(s), Location of POE, and Location(s) of POD for Groundwater Protection Figure No. X

Figure showing the location(s) of the soil source(s), location of POE, and location(s) of POD for Surface Water Protection Figure No.

TIER 2 EVALUATION

LIST OF TABLES

Additional Tables & Information

1. See Soil Boring Logs

TABLE OF CONTENTS

SITE INFORMATION AND TIER 1 FORMS (Continued)

NDRBCA REPORT

TABLE OF CONTENTS

NDRBCA REPORT

All maps/figures submitted to the EGLE must include a bar scale, legend, north arrow. Include maps showing all sampling points (soil, groundwater, soil vapor, and subslab vapor, and ambient air) and date prepared.

No. In report?

LIST OF FIGURES

Additional Figures

Description No. of Pages

Documentation of LNAPL Disposal Manifests

1. Soil Boring Logs X

Monitoring Well Construction Logs X

Documentation for Calculation of Vertical Gradients Documentation of Soil and Water Disposal Manifests Operation and Maintenance Plan for Each Corrective Action Technology (as appropriate) Monitoring Plan for Each Corrective Action Technology (as appropriate)

2. Documentation for Calculation of Representative Concentrations X

3. Laboratory Analytical Report X

Documentation of Environmental Covenants

4. Output Tables from the NDRBCA Computational Software X

SITE INFORMATION AND TIER 1 FORMS (Continued) No. In report?

ATTACHMENTS

Additional Attachments

NDRBCA REPORT FORM NO. 1

Facility ID number (if any): LUST ID 1464 Site address: 701 Dakota Avenue Date form completed: 13-July-23 Form completed by: Tim Adair

Site address

Status of facility Active Inactive

Is off-site soil impacted? Yes No

Is off-site soil data available? Yes No

Is groundwater impacted? On-site Off-site

Groundwater flow direction Shallowest historical depth to groundwater ft bgs; Period to 4/3/2023 Average historical depth to groundwater ft bgs; Period to 4/3/2023 Has the source of release been identified?

Was LNAPL ever detected in a well/excavation?

Was LNAPL removed?

When was LNAPL last detected? Date Has surface water been impacted?

Has a water supply well been impacted?

Is there a public water supply well within 1,000 ft? No Distance ft; Direction Is there a private water supply well within 1,000 ft? No Distance ft; Direction

TIER 1 Evaluation TIER 2 Evaluation Closure under Tier 1 Closure under Tier 2 Remediate to Tier 1 Remediate to Tier 2 Perform monitoring Go to Tier 2 Go to Tier 3

Print Owner or Representative Name

EXECUTIVE SUMMARY

The Dakota Avenue corridor has various Recognized Environmental Conditions (RECs) from incidents and site activites that are not related to the Site for this report. There are off-site impacts, but not due to on-site contaminants.

Off-site soil data is not included in this report, but RP's had access to the data provided in a different report submitted to the NDDEQ.

See Above. The source of Off-site impacts is not from On-site contaminants.

N/A N/A

East

5.5 4/3/2023

5.5 4/3/2023 Yes, former underground stroage tank (UST) basin area No No (N/A)

N/A No No

Signature of Owner or Representative Date

N/A N/A

RECOMMENDATIONS

BASIS OF RECOMMENDATION AND ADDITIONAL NOTES

It's recommended that the Site receives closure under the Tier 1 Evaluation. Site Representative Concentrations in soil and groundwater were compared to Tier 1 Commercial/Industrial Worker and Construction Worker Risk-Based Screening Levels (RBSL) for each Route of Exposure with a complete pathway and no exceedances were identified. On-site contaminants do not pose a risk to any sensitive receptors.

Tim Adair

Tadair@earthsys.net 701-751-4868

701 Dakota Avenue, Wahpeton, ND 58075

Email Address Phone Number

Perform monitoring

Earth Systems 4501 Coleman Street, Suite 103, Bismarck, ND 58501 Name of Company Address

REPORT PREPARED BY

I attest that the information upon which this report is based is complete and true to the best of my knowledge.

7/14/2023

NDRBCA REPORT FORM NO. 2

Date form completed: 13-July-23 Form completed by: Tim Adair

Site name:

Facility ID number (if any):

Site address:

Date site discovered:

Responsible Party Information:

Business name:

Contact person name:

Contact person address:

Contact person Phone No.:

Contact person Email ID:

OPERATING?

Petroleum UST site Petroleum AST site Oil and gas facility/site Manufacturing facility Pesticide facility Dry cleaning facility Land fill Other

Have the on-site subsurface utilities been identified? YES NO Range of depth to utilities (ft bgs) Type of utilities Electrical, Water, Sewer Have the utilities been screened for vapor levels? YES NO If YES, attach documentation of vapor monitoring results.

If drinking water lines potentially impacted, has drinking water been tested for VOCs? N/A If YES, attach documentation of drinking water monitoring results.

SITE INFORMATION

Former M & H Gas Station

LUST ID 1464

701 Dakota Avenue, Wahpeton, ND 58075

6 ft

CITY OF WAHPETON

CITY OF WAHPETON

PO BOX 490, WAHPETON ND 58074-0490

SITE TYPE

For facility type identified as "other", discuss specific details below:

Subsurface Utilities

ADDITIONAL NOTES FOR FACILITY AND UTILITIES

Attachments: (1) Site location map; (2) Site map showing property boundaries, past and current site features (e.g., storage systems, process areas, distribution areas, location of release, location of on and off-site monitoring points, location of public and private water wells within 1,000 ft, location of surface water features within 1,000 ft, ecological receptors within 1,000 ft, location of excavation, and location of remedial system, if any).

See City of Wahpeton for additional information regarding subsurface utilities.

NDRBCA REPORT FORM NO. 3

Date form completed: 13-July-23 Form completed by: Tim Adair

Attachments: None.

SITE DISCOVERY

Instructions: Describe (i) site operations, (ii) how the site was discovered (e.g., sheen in utilities and observation wells, sudden loss of product in tanks, Phase I or II investigations as part of real estate transactions, accidental release, citizen compliant of odors) (iii) when was the release occurred, (iv) location of release, (v) chemicals stored, used, and released at the facility, (vi) quantity released (if known) etc.

The former M&H gas station is located at the southwest corner of 7th Street North and Dakota Avenue in Wahpeton, North Dakota and was operated from 1951 to 1994. It ceased being operated as a gas station when the operator relocated. The main building and an underground storage tank (UST) were removed from the property the same year, along with five (5) cubic yards of petroleum contaminated soil. In 2006, two (2) additional USTs were removed. During the UST removals, samples of pea gravel were tested and exhibited signs of petroleum contamination. The petroleum contaminated pea gravel of the UST basin was left in place and backfilled. An additional investigation was conducted along Dakota Avenue in 2009, and soil impacts adjacent to the former M & H Gas Station Site were identified. Land surrounding the Site is used for commercial purposes.

In 1994, gas station activities ceased. The Site remained idle until the City of Wahpeton purchased it in 2021 with the intention of turning it into a green space. The Site has remaining portions of concrete and bituminous parking lot in place.

NDRBCA REPORT FORM NO. 4

Date form completed: 13-July-23 Form completed by: Tim Adair

New Tank ID Number(s) Product Capacity Installation

Date Removal

Date Closure in Place Date

Temporarily closed

Yes No ND1464_1* gasoline 10000 6/30/1986 10/25/2006 ND1464_2* gasoline 10000 6/30/1986 10/25/2006 ND1464_3 gasoline 2,000 6/30/1951 6/1/1986

ND1464_4 gasoline 2,000 6/30/1951 6/1/1986 ND1464_5 gasoline 15000 7/1/1971 10/10/1994

Tank number(s) identified with " * " are associated with the confirmed release(s).

Attachment: Figure 2 Site Map Showing Site Boundaries and Past and Present Site Features

N/A

UNDERGROUND STORAGE TANK TYPES

ADDITIONAL NOTES

In Use

NDRBCA REPORT FORM NO. 5

Date form completed: 13-July-23 Form completed by: Tim Adair

Residential Residential Non-residential Non-residential Other (please explain below) Other (please explain below)

Attachments: (1) Land use map (Radius of 1,000 feet); (2) Site map showing buildings within 1,000 ft of source

Currently, site is a vacant lot developed for commercial use. The City of Wahpeton purchased the location in 2021 with the intention of turning it into a green space. Surrounding area is also highly devloped for commercial use.

LAND USE (ON-SITE AND OFF-SITE)

Current On-site Land Use Allowable Future On-site Land Use

Is site located in wellhead protection area?

Is site located in wellhead protection area?

- Describe the current and potential future use of the on-site land and surrounding land, groundwater, surface water, and sensitive habitats within 1,000 ft of the site boundary and in all directions (N, S, E, and W).

NDRBCA REPORT FORM NO. 6

Date form completed: Form completed by: Tim Adair

Date

April 2023

April 2023

June 2023

Include completed Form 20 for list of references. Page 1 of 1

CHRONOLOGY OF EVENTS

Instructions: Describe site characterization, sampling, and remediation activities including installation of soil borings, monitoring wells, soil vapor monitoring points, subslab vapor points, slug tests, institutional controls, LNAPL removal, etc.

Refer to Environemtnal Site Assesment Report submitted June 2023 for additional information.

Refer to Environemtnal Site Assesment Report (June 2023)

Five soil borings were installed utilizing a direct push technology drilling (DPT) rig to identify contaminants of concern at the Site. Each soil boring was field screened at 2-foot intervals using an organic vapor analyzer – photoionization detector (OVA-PID). Duplicate soil samples were retained from each boring interval providing the greatest indication of environmental impacts based on field observations (OVA-PID readings, visual, or olfactory).

The soil samples were submitted to a North Dakota certified laboratory for total petroleum hydrocarbons (TPH) as diesel range organics (DRO) and gasoline range organics (GRO), benzene, toluene, ethylbenzene, and xylene (BTEX), volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and polycyclic aromatic hydrocarbons (PAH) analysis.

Three temporary groundwater monitoring wells were installed at the Site. The wells were constructed with one-inch polyvinyl chloride (PVC) risers and 0.010-inch slotted PVC screen. The temporary well screens were installed to bisect the groundwater table. Groundwater grab samples were collected and submitted to a North Dakota certified laboratory for TPH, VOCs, SVOCs, BTEX, and PAH analysis.

Date form completed: 13-July-23 Form completed by: Tim Adair

No. of soil borings advanced Range of depth of soil borings 0 ft bgs to 20 ft bgs No. of soil samples collected from soil borings and analyzed No. of permanent groundwater monitoring wells installed No. of permanent active groundwater monitoring wells No. of abandoned permanent groundwater monitoring wells No. of nested permanent groundwater monitoring well pairs No. of temporary groundwater monitoring wells installed No. of temporary groundwater monitoring wells still active Range of depth of permanent groundwater monitoring wells 0 ft bgs to 20 ft bgs No. of piezometers installed No. of piezometers still active No. of LNAPL recovery wells No. of soil vapor extraction wells No. of soil vapor monitoring ports installed No. of soil vapor samples analyzed (and no. of events) No. of subslab vapor monitoring points installed No. of subslab vapor samples analyzed (and no. of events) No. of ambient air samples analyzed by laboratory (not PIDs) No. of soil samples analyzed for geotechnical parameters No. of tanks removed No. of soil samples collected during tank removal No. of soil samples collected post excavation, if any

Attachments: Tables 1 to 8 (see table of contents for specifics)

FORM NO. 7

COMPREHENSIVE SUMMARY OF DATA

Please confirm that the above information is consistent with the chronology, figures, and tables. For example, if the number of monitoring wells installed is 10, Table 2 must list 10 wells, Figure 6 must show 10 wells, Attachment 3 must show 10 well construction details, and the chronology must match the dates of well installation shown on Table 2. Any inconsistencies must be explained in the space provided below. The total number of samples must include the duplicates and also the number of duplicates.

ADDITIONAL NOTES COMPREHENSIVE SUMMARY OF DATA

N/A

NDRBCA REPORT FORM NO. 9

Facility ID number (if any): Site address:

Date form completed: Form completed by:

Predominant soil type in vadose zone Predominant soil type in saturated zone

Range of measured groundwater level [ft bgs] Average depth to stabilized water level [ft bgs] Estimated depth to top of zone (ft bgs) Estimated depth to bottom of zone (ft bgs) Estimated thickness of water bearing zone (ft) Aquifer type (confined/unconfined/perched, etc.)

Predominant flow direction Hydraulic gradient (i) [--] Hydraulic conductivity (K) [cm/year] Hydraulic conductivity test method Darcy velocity (K × i) [cm/year - calculated] Predominant vertical gradient (Zone 1 to Zone 2) [--] Predominant vertical gradient (Zone 2 to Zone 3) [--]

Show details of vertical gradient calculations in Attachment 4, if available.

Site stratigraphy and Geological Cross Sections are provided in the Phase II Environmental site Assessment Report, submitted in June 2023

Not measured

Tank backfill material

Silty Clay (CL)

SITE STRATIGRAPHY AND HYDROGEOLOGY

STRATIGRAPHY

Type of Soil

Fill40 -

4 - 20

Silty Clay (CL)

Silty Clay (CL)

HYDROGEOLOGY

Zone 1 Zone 2 Zone 3

NA NA

5.56 NA NA

5 NA NA

100 NA NA

15 NA NA

Unconfined NA NA East NA NA

(Default) NA NA

NA NA NA

(Default) NA NA

(Default) NA NA

Depth [feet]

Attachments: (1) site stratigraphy and cross sections; ; (2) Soil boring logs;

4 - 12

NA NA NA

ADDITIONAL NOTES FOR SITE STRATIGRAPHY AND HYDROGEOLOGY

(Default) NA NA

NDRBCA REPORT FORM NO. 10

Date form completed: 13-July-23 Form completed by: Tim Adair

Method Dry bulk density (ρb) [g/cm3] Estimated Measured Default Estimated porosity (θT) [cm3/cm3] Estimated Measured Default Water content (θw)[cm3/cm3] Estimated Measured Default Fractional organic carbon content (foc) [g-C/g-soil] Estimated Measured Default

Provide details of measured values below.

Method Dry bulk density (ρb) [g/cm3] Estimated Measured Default Estimated porosity (θT) [cm3/cm3] Estimated Measured Default Water content (θw)[cm3/cm3] Estimated Measured Default Fractional organic carbon content (foc) [g-C/g-soil] Estimated Measured Default

Provide details of measured values below.

0.15

GEOTECHNICAL PARAMETERS

VADOSE ZONE

Mean/Range 1.5

0.43

0.002

ADDITIONAL NOTES GEOTECHNICAL PARAMETERS

Attachments: (1) Attachment 2: Soil boring logs;

0.006

SATURATED ZONE

Values/Range

1.5 0.43 0.15

Site Fate and Transport Paramaters values are the default values used for generating Tier 1 RBSLs established by NDDEQ.

NDRBCA REPORT FORM NO. 11

Date form completed: 13-July-23 Form completed by: Tim Adair

Has the plume impacted the surface water body? Yes No Yes No

Please describe the surface water body:

Approximate elevation of bottom of surface water body (ft msl)

Is the approximate bottom of surface water body above the groundwater table? Yes No

Is groundwater to surface water pathway complete? Yes No

Provide justification for your choice:

GROUNDWATER TO SURFACE WATER PATHWAY

Are surface waters of the state located within 1,000 ft downgradient of the source area?

(If No, proceed to the next Form)

Attachments: (1) Figure 18: Site map showing the surface water feature including storm water sewer;

Unknown, but given distance from site (>2500 feet), won't complete the pathway.

(If Yes, groundwater to surface water pathway is not complete)

ADDITIONAL NOTES FOR GROUNDWATER TO SURFACE WATER

N/A

NDRBCA REPORT FORM NO. 12 - ON-SITE RESIDENT

Date form completed: 13-July-23 Form completed by: Tim Adair

SURFACE SOIL (0 to 2 ft bgs) 1 C 1 C

NC NC

SUBSURFACE SOIL (>2 ft bgs to water table) (Recommendation is to Use Soil Vapor RBTLs) 0 C 1 C

NC NC

GROUNDWATER

0 C 1 C

NC NC

2 C 1 C

NC NC

Notes:

C : Complete Pathway; NC : Not Complete RC: Representative concentration N/A: Not available Page 1 of 7 *: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map; (3) Figure 11: Groundwater Concentrations or Contour Map

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

Indoor inhalation of vapors from groundwater

Currently (2023), there are no residential properties located on or near the site. Land use in vicinity is non-residential. Pathway incomplete.

N/A Future land use is a non-residential greenspace. N/A

EXPOSURE MODEL - ON-SITE RESIDENT

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Currently (2023), there are no residential properties located on or near the site. Land use in vicinity is non-residential. Pathway incomplete. City of Wahpeton supplies domestic water to inhabitants.

N/A Future land use is a non-residential greenspace. City of Wahpeton supplies domestic water to inhabitants.

N/A

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Currently (2023), there are no residential properties located on or near the site. Land use in vicinity is non-residential. Pathway incomplete.

N/A Future land use is a non-residential greenspace. N/A

Indoor inhalation of vapors Currently (2023), there are no residential properties located on or near the site. Land use in vicinity is non-residential. Pathway incomplete.

N/A Future land use is a non-residential greenspace. N/A

NDRBCA REPORT FORM NO. 12 - ON-SITE COMMERCIAL/INDUSTRIAL WORKER

Date form completed: 13-July-23 Form completed by: Tim Adair

SURFACE SOIL (0 to 2 ft bgs) 1 C 1 C

NC NC

SUBSURFACE SOIL (>2 ft bgs to water table) (Recommendation is to Use Soil Vapor RBTLs) 0 C 1 C

NC NC

GROUNDWATER

2 C 1 C

NC NC

2 C 1 C

NC NC

Notes:

C : Complete Pathway; NC : Not Complete RC: Representative concentration N/A: Not available Page 2 of 7 *: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map; (3) Figure 11: Groundwater Concentrations or Contour Map

EXPOSURE MODEL - ON-SITE COMMERCIAL/INDUSTRIAL WORKER

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

Indoor inhalation of vapors

No current buildings on-site, pathway incomplete.

N/A Future use will be a greenspace (no on-site buildings).

N/A

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Complete, evaluated at Tier 1 RBSL's SB2 (2'-4') Complete, evaluated at Tier 1 RBSL's SB2 (2'-4')

Domestic Use (Ingestion, dermal contact, and inhalation of vapors)

No identified use of groundwater on site. N/A No identified future use of groundwater on site. N/A

Indoor Inhalation of Vapors

No current buildings on-site, pathway incomplete.

N/A Future use will be a greenspace (no on-site buildings).

N/A

NDRBCA REPORT FORM NO. 12 - ON-SITE CONSTRUCTION WORKER

Date form completed: 13-July-23 Form completed by: Tim Adair

EXPOSURE MODEL - ON-SITE CONSTRUCTION WORKER

SOIL UP TO DEPTH OF CONSTRUCTION

1 C 1 C

NC NC

Notes:

C : Complete Pathway; NC : Not Complete RC: Representative concentration Page 3 of 7 *: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map;

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Currently, no construction activities on-site.

N/A Complete, evaluated at Tier 1 RBSL's SB1 (8'-10'), SB2 (2'-4'), SB3

(6'- 8'), SB4 (4'-6'), SB5 (10'-

12')

NDRBCA REPORT FORM NO. 12 - OFF-SITE RESIDENT

Date form completed: 13-July-23 Form completed by: Tim Adair

EXPOSURE MODEL - OFF-SITE RESIDENT

SURFACE SOIL (0 to 2 ft bgs) 1 C 1 C

NC NC

SUBSURFACE SOIL (>2 ft bgs to water table) (Recommendation is to Use Soil Vapor RBTLs) 0 C 1 C

NC NC

GROUNDWATER

0 C 1 C

NC NC

2 C 1 C

NC NC

Notes:

C : Complete Pathway; NC : Not Complete RC: Representative concentration N/A: Not available Page 4 of 7 *: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map; (3) Figure 11: Groundwater Concentrations or Contour Map

Indoor inhalation of vapors from groundwater

Land use in vicinity is non-residential. Pathway incomplete.

N/A Land use in vicinity is non-residential. Pathway incomplete.

N/A

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Land use in vicinity is non-residential. Pathway incomplete.

N/A Land use in vicinity is non-residential. Pathway incomplete.

N/A

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Land use in vicinity is non-residential. Pathway incomplete.

N/A Land use in vicinity is non-residential. Pathway incomplete.

N/A

Indoor inhalation of vapors Land use in vicinity is non-residential. Pathway incomplete.

N/A Land use in vicinity is non-residential. Pathway incomplete.

N/A

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

NDRBCA REPORT FORM NO. 12 - EXPOSURE MODEL - OFF-SITE COMMERCIAL/INDUSTRIAL WORKER

Date form completed: 13-July-23 Form completed by: Tim Adair

SURFACE SOIL (0 to 2 ft bgs) 1 C 1 C

NC NC

SUBSURFACE SOIL (>2 ft bgs to water table) (Recommendation is to Use Soil Vapor RBTLs) 0 C 1 C

NC NC

GROUNDWATER

2 C 1 C

NC NC

2 C 1 C

NC NC

*: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map; (3) Figure 11: Groundwater Concentrations or Contour Map

Indoor Inhalation of Vapors

Off-site impacts are attributed to their own separate incidents and were not apart of this evaluation. Pathway incomplete. Protection of Groundwater Pathway evaluated in Form 13.

N/A Off-site impacts are attributed to their own separate incidents and were not apart of this evaluation. Pathway incomplete. Protection of Groundwater Pathway evaluated in Form 13.

N/A

EXPOSURE MODEL - OFF-SITE COMMERCIAL/INDUSTRIAL WORKER

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation. Pathway incomplete.

N/A Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation. Pathway incomplete.

N/A

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

Indoor inhalation of vapors

Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation. Pathway incomplete.

N/A Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation. Pathway incomplete.

N/A

Domestic Use (Ingestion, dermal contact, and inhalation of vapors)

No identified use of groundwater off-site. N/A No identified future use of groundwater off-site. N/A

NDRBCA REPORT FORM NO. 12 - OFF-SITE CONSTRUCTION WORKER

Date form completed: 13-July-23 Form completed by: Tim Adair

SOIL UP TO DEPTH OF CONSTRUCTION

1 C 1 C

NC NC

Notes:

C : Complete Pathway; NC : Not Complete RC: Representative concentration Page 6 of 7 *: If space is not sufficient to list the monitoring points within the exposure domain, then please include the list of monitoring points in an attachment/table showing each exposure domain and monitoring points within the domain.

Attachments: (1) Figure 6: Site map showing soil boring and monitoring well locations (including drinking water wells onsite); (2) Figure 10: Soil Concentrations or Contour Map;

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation.

Pathway incomplete.

N/A Off-site impacts are attributed to their own separate incidents and are not apart of this evaluation.

Pathway incomplete.

N/A

EXPOSURE MODEL - OFF-SITE CONSTRUCTION WORKER

MEDIA AND ROUTE

OF EXPOSURE

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

C/NC Justification for Route of Exposure Monitoring Points Exposure Domain for Calculating RC* C/NC Justification for Route of Exposure

Monitoring Points Exposure Domain for Calculating RC*

NDRBCA REPORT FORM NO. 12 - SUMMARY OF EM

Date form completed: 13-July-23 Form completed by: Tim Adair

SURFICIAL SOIL FOR RESIDENT AND COMMERCIAL/INDUSTRIAL WORKER AND SOIL UPTO DETPH OF CONSTRUCTION FOR CONSTRUCTION WORKER

NC C NC NC C C NC NC NC NC NC NC

SUBSURFACE SOIL (>2 ft bgs to water table) (Recommendation is to Use Soil Vapor RBTLs)

NC NC NA NC NC NA NC NC NA NC NC NA

GROUNDWATER

NC NC NA NC NC NA NC NC NA NC NC NA

NC NC NA NC NC NA NC NC NA NC NC NA

Notes C: Complete Pathway NC: Not Complete NA: Not applicable Page 7 of 7

SUMMARY OF EXPOSURE MODEL (COMPLETE ROUTES OF EXPOSURE HIGHLIGHTED)

MEDIA AND ROUTE

OF EXPOSURE

ON-SITE RECEPTOR OFF-SITE RECEPTOR

CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS CURRENT CONDITIONS ALLOWABLE FUTURE CONDITIONS

Resident Commercial/

Industrial Worker

Construction Worker

Construction Worker Resident

Commercial/ Industrial Worker

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Indoor inhalation of vapors

Construction Worker Resident

Commercial/ Industrial Worker

Ingestion of and dermal contact with, and inhalation of vapors and particulates

Indoor inhalation of vapors

Construction Worker Resident

Commercial/ Industrial Worker

NDRBCA REPORT FORM NO. 13

Date form completed: 13-July-23 Form completed by: Tim Adair

For this pathway provide the following:

Location of POE: feet (ft) from downgradient edge of source

Concentration at POE: MCL Tapwater RBTL Other

Location of POD (include well ID and location):

Indoor Inhalation of Vapors

CONSIDERATION OF GROUNDWATER PROTECTION PATHWAY

Per Section 5.3.3 of NDRBCA Guidance document this pathway requires the (i) location of point of exposure (POE), (ii) acceptable concentration at POE, and (iii) location of point of demonstration (POD). Based on these RBTLs are developed for (i) groundwater POD, (ii) subsurface soil, and (iii) surface soil.

TMW-3 (source), distance to POD from source = 0 feet Note, there may be multiple PODs.

ADDITIONAL NOTES FOR CONSIDERATION OF GROUNDWATER PROTECTION PATHWAY

Land use for the down-gradient adjacent property is commercial and users provided with domestic use water from municipality. The Groundwater Protection Pathway is only complete for Indoor Inhalation of vapors, therefore allowable concentrations are based solely on the Indoor Inhalation of Vapors from Groundwater target levels.

Furthermore domestic water is supplied to the City of Wahpeton from a municipal source.

Attachments: (1): Figure showing the location(s) of the soil source(s), location of POE, and location(s) of POD for Groundwater Protection

Facility ID number (if any): LUST ID 1464 Date form completed: 13-July-23

C NC NC NC

Rep. Rep. Rep. Conc. Rep. Conc.

Conc. Conc. (Max Conc.) (Max Conc.)

[mg/kg] [mg/kg] [mg/kg] [mg/kg] [mg/L] [mg/L] [mg/L] [mg/L] Benzene 5.4.E-03 5E+01 NE NA NA NA NA NA NA NA NA Ethylbenzene 1.0.E-01 3E+02 NE NA NA NA NA NA NA NA NA Isopropylbenzene (Cumene) 1.1.E-01 1E+04 NE NA NA NA NA NA NA NA NA Naphthalene 6.7.E-01 8.6E+01 NE NA NA NA NA NA NA NA NA 1,2,4-Trimethylbenzene 1.3.E+00 1.8E+03 NE NA NA NA NA NA NA NA NA 1,3,5-Trimethylbenzene 8.2.E-01 1.5E+03 NE NA NA NA NA NA NA NA NA Xylene (total) 2.0.E-01 2.5E+03 NE NA NA NA NA NA NA NA NA Benzo(a)anthracene 3.0.E-02 2.1E+02 NE NA NA NA NA NA NA NA NA Chrysene 3.0.E-02 2.1E+04 NE NA NA NA NA NA NA NA NA Fluoranthene 2.0.E-02 3.0E+04 NE NA NA NA NA NA NA NA NA

SLs E/NE SLs E/NE

FORM NO. 15 - ON-SITE COMMERCIAL/INDUSTRIAL WORKER (CURRENT & FUTURE CONDITIONS)

COMPARISON OF REPRESENTATIVE CONCENTRATIONS WITH TIER 1 RBSLs- ON-SITE COMMERCIAL/INDUSTRIAL WORKER (CURRENT & FUTURE CONDITIONS)

CHEMICALS OF CONCERN

SURFACE SOIL SUBSURFACE SOIL GROUNDWATER

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates Indoor inhalation of vapors

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Indoor inhalation of vapors

Site address: 701 Dakota Avenue Form completed by: Tim Adair

SLs E/NESLs E/NE

Date form completed: 13-July-23

C

Benzene NE Ethylbenzene NE Isopropylbenzene (Cumene) NE Naphthalene NE 1,2,4-Trimethylbenzene NE 1,3,5-Trimethylbenzene NE Xylene (total) NE Benzo(a)anthracene NE Chrysene NE Fluoranthene NE

Site address: 701 Dakota Avenue Form completed by: Tim Adair

SURFACE SOIL

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

FORM NO. 15 - ON-SITE CONSTRUCTION WORKER (CURRENT & FUTURE CONDITIONS)

COMPARISON OF REPRESENTATIVE CONCENTRATIONS WITH TIER 1 RBSLs- ON-SITE CONSTRUCTION WORKER ( CURRENT & FUTURE CONDITIONS)

CHEMICALS OF CONCERN

3.69E+02 5.61E+03 8.79E+03 5.79E+02

E/NE

1.74E+03 1.75E+05

1.37E+03 1.22E+03 2.60E+03

3.00.E-02

SLs

5.40.E-03 1.03.E-01 1.10.E-01 6.70.E-01 1.31.E+00 8.20.E-01

9.99E+03

Rep.

Conc.

[mg/kg]

3.00.E-02 2.00.E-02

2.00.E-01

NDRBCA REPORT FORM NO. 15 - SUMMARY OF EXCEEDANCES

Date form completed: 13-July-23

SURFACE SOIL/ SOIL UP TO DEPTH OF CONSTRUCTION FOR CONSTRUCTION WORKER

NE NE NE NE NA NA NA NA

SUBSURFACE SOIL (SOIL VAPOR)

NA NA NA NA NA NA NA NA

GROUNDWATER

NA NA NA NA NA NA NA NA

NA NA NA NA NA NA NA NA

Notes Page 3 of 3E: Exceeded NE: Not exceeded NA: Not applicable

SUMMARY OF EXCEEDANCES

ROUTES OF EXPOSURE

ON-SITE RECEPTOR OFF-SITE RECEPTOR

CURRENT CONDITIONS REASONABLY ANTICIPATED FUTURE

CONDITIONS

Commercial/Ind ustrial Worker

CURRENT CONDITIONS REASONABLY ANTICIPATED FUTURE

CONDITIONS

Resident Construction Worker Resident Construction

Worker

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Indoor inhalation of vapors

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Commercial/Ind ustrial Worker

Construction Worker Resident Commercial/Ind ustrial Worker Construction

Worker

Site address: 701 Dakota Avenue Form completed by: Tim Adair

Indoor inhalation of vapors

Resident Commercial/Ind ustrial Worker

NDRBCA REPORT FORM NO. 15 - SUMMARY OF EXCEEDANCES

Date form completed: 13-July-23

SURFACE SOIL/ SOIL UP TO DEPTH OF CONSTRUCTION FOR CONSTRUCTION WORKER

NE NE NE NE NA NA NA NA

SUBSURFACE SOIL (SOIL VAPOR)

NA NA NA NA NA NA NA NA

GROUNDWATER

NA NA NA NA NA NA NA NA

NA NA NA NA NA NA NA NA

Notes

Site address: 701 Dakota Avenue Form completed by: Tim Adair

Indoor inhalation of vapors

Resident Commercial/Ind ustrial Worker

Construction Worker

Ingestion of and dermal contact with, and outdoor inhalation of vapors and particulates

Indoor inhalation of vapors

Domestic use of water (ingestion of and dermal contact with, and inhalation of vapors due to indoor water use)

Commercial/Ind ustrial Worker

Construction Worker Resident Commercial/Ind ustrial Worker Construction

Worker

E: Exceeded NE: Not exceeded NA: Not applicable

SUMMARY OF EXCEEDANCES

ROUTES OF EXPOSURE

ON-SITE RECEPTOR OFF-SITE RECEPTOR

CURRENT CONDITIONS REASONABLY ANTICIPATED FUTURE

CONDITIONS

Commercial/Ind ustrial Worker

CURRENT CONDITIONS REASONABLY ANTICIPATED FUTURE

CONDITIONS

Resident Construction Worker Resident

NDRBCA REPORT FORM NO. 16

Date form completed: 13-July-23

COMPARISON OF REPRESENTATIVE CONCENTRATIONS WITH TIER 1 GROUNDWATER PROTECTION TARGET CONCENTRATIONS 144 ft

Soil Source Rep.

Conc. 1

Allowable Soil Conc. 2 C

GW Source Rep.

Conc. 3

Allowable GW Conc. at the Source

C

POD Rep.

Conc. 5

Allowable GW Conc. at a POD 6 C

[mg/kg] [mg/kg] E/NE [mg/L] [mg/L] E/NE [mg/L] [mg/L] E/NE

POD WELL NO. (TMW-3)

DISTANCE FROM SOURCE (0 ft) RECENT TREND (Decreasing)

Benzene 5.40E-03 7.38E+00 NE 2.24E-02 2.17E+00 NE Ethylbenzene 1.03E-01 6.47E+01 NE 5.02E-02 6.82E+00 NE Isopropylbenzene (Cumene) 1.10E-01 3.04E+03 NE 3.34E-02 2.07E+02 NE

Naphthalene 6.70E-01 8.17E+01 NE 1.11E-01 2.61E+00 NE

1,2,4-Trimethylbenzene 1.31E+00 6.10E+02 NE 1.00E+00 4.76E+01 NE 1,3,5-Trimethylbenzene 8.20E-01 4.80E+02 NE 1.73E-01 3.79E+01 NE Xylene (total) 2.00E-01 5.60E+02 NE 1.23E-01 6.84E+01 NE Benzo(a)anthracene 3.00E-02 2.42E+05 NE ND (0.002) 6.82E+01 NE Chrysene 3.00E-02 5.22E+07 NE 7.10E-04 1.44E+04 NE Fluoranthene 2.00E-02 NA NE 1.90E-04 NA NE

6 47E+01 NE NE

1-Methylnapthalene 6.72E-02 NA NE 1.01E-01 NA NE 2-Methylnapthalene 9.20E-02 NA NE 9.20E-02 NA NE

Pyrene 2.00E-02 NA NE ND (0.002) NA NE

NOTE: Use the NDRBCA Computational Software to calculate the (i) soil source conc., (ii) GW source conc., and (iii) the point of demonstration (POD) well conc.

1: The soil source representative concentrations have to be calculated and entered here. (Max Concentration) 2: Allowable soil concentrations at the source protective of groundwater at the POE.

3: The groundwater source representative concentrations have to be calculated and entered here. 4: Allowable groundwater concentrations at the source protective of groundwater at the POE.

5: Represents the representative concentrations in the POD well 6: Represents the allowable groundwater concentrations at a POD protective of a POE.

For representative concentrations, refer Attachment 3:

E: Representative on-site concentration exceeds calculated POD well concentration. NE: Representative on-site concentration does not exceed calculated POD well concentration.

Attachments: (i) Figure 20: Showing the location(s) of the soil source(s), location of POE, and location(s) of POD. (ii) Attachment 8: Documentation for Calculation of Representative Concentrations

Site address: 701 Dakota Avenue Form completed by: Tim Adair

Distance from source to the point of exposure (POE):

CHEMICALS OF CONCERN

COMPARISON FOR SOIL SOURCE (MW-1) COMPARISON FOR GROUNDWATER

SOURCE (MW-1) COMPARISON FOR POINT OF DEMONSTRATION (POD) WELLS

NDRBCA REPORT FORM NO. 18(a)

Date form completed: 13-July-23

Receptor Complete Exposure Pathway for Which Representative Conc. Exceeds Screening Level

Tier 2 Evaluation Environmental covenant Active remediation Other Tier 2 Evaluation Environmental covenant Active remediation Other Tier 2 Evaluation Environmental covenant Active remediation Other Tier 2 Evaluation Environmental covenant Active remediation Other Tier 2 Evaluation Environmental covenant Active remediation Other

Site address: 701 Dakota Avenue Form completed by: Tim Adair

CONCLUSION AND RECOMMENDATION (ON-SITE RECEPTORS)

Instructions: Based on the results of Tier 1 Evaluation, (refer Form 15(9)), discuss each media, pathway and receptor combination that exceeds the Tier 1 screening levels. For each exceedance, propose actions to manage the risk. Actions can include (i) Tier 2 evaluation, (ii) environmental covenant to eliminate the pathway, (iii) an active remediation or a combination of these.

Media Proposed Management Strategy

ADDITIONAL NOTES FOR CONCLUSION AND RECOMMENDATION

Currently, site is vacant land with a concrete and asphalt surface cover that limits the pathway for inhalation of vapors from soil. In the future Property is slated to be used as a greenspace with no plans for on-site buildings. During the Tier 1 exposure model evaluation, all pathways were found to be not complete except for the Surface Soil pathway, but after comparing site representative conentrations to Tier 1 RBSLs no exceedances were identified. It's recommended to pursue site closure under the Tier 1 Evaluation.

Date form completed: 13-July-23

Yes No

Yes No

FORM NO. 18(b)

1.a.) Can contaminants associated with the site leach, dissolve, or otherwise migrate to groundwater?

1.b.) Are contaminants associated with the site mobile in groundwater?

1.c.) Does groundwater from the site discharge to ecological receptor habitat?

Screening Checklist for Potential Receptors and Habitat Level 1 Checklist B

1. Is the boundary of the contaminated area less than ½ mile to a surface water body (stream, river, pond, lake, etc.)?

3. Are contaminated soils uncovered or otherwise accessible to ecological receptors and the elements?

4. Are there federal or state rare, threatened, or endangered species on or within ½ mile of the contaminated area?

5. Are there one or more environmentally sensitive areas at or within ½ mile of the contaminated area?

Ecological Risk Evaluation

Question 1: Could contaminants associated with the site reach ecological receptors via groundwater?

2. Are wetlands (as defined by the 1987 Corps of Engineers’ Delineation Manual) on or adjacent to the site?

Screening Checklist for Potential Receptors and Habitat Level 1 Checklist A

Site address: 701 Dakota Avenue Form completed by: Tim Adair

Question 5: Could contaminants reach ecological receptors via inhalation of volatilized contaminants or contaminants adhered to dust in ambient air or in subsurface burrows?

5.a.) Are contaminants present on the site volatile?

5.b.) Could contaminants on the site be transported in air as dust or particulate matter?

Question 6: Could contaminants reach ecological receptors via direct ingestion of soil, plants, animals, or contaminants?

2.a.) Is Non-Aqueous Phase Liquid (NAPL) present at the site?

2.b.) Is NAPL migrating?

2.c.) Could NAPL discharge occur where ecological receptors are found?

Question 3: Could contaminants reach ecological receptors via erosional transport of contaminated soils or via precipitation runoff?

3.a.) Are contaminants present in surface soils?

3.b.) Can contaminants be leached from or be transported by erosion of surface soils?

Question 2: Could contaminants from the site reach ecological receptors via migration of NAPL?

Question 4: Could contaminants reach ecological receptors via direct contact?

4.a.) Are contaminants present in surface soil or on the surface of the ground?

4.b.) Are potential ecological receptors on the site?

6. Are commercially or recreationally important species (fauna or flora) on or within ½ mile of the contaminated area?

This Ecological Risk Evaluation was based off site observations, the National Wetland Inventory, and the North Dakota Game and Fish Department.

6.a.) Are contaminants present in surface and shallow subsurface soils or on the surface of the ground?

6.b.) Are contaminants found in soil on the site taken up by plants growing on the site?

6.d.) Could contaminants present on the site bioaccumulate?

6.c.) Do potential ecological receptors on or near the site feed on plants (e.g., grasses, shrubs, forbs, trees, etc.) found on the site?

ADDITIONAL NOTES FOR ECOLOGICAL RISK EVALUATION

TABLES

TABLE 1

SOIL - VOCs

M Gas Station T132N, R47W, Sec. 8 SWNW

Richland County, North Dakota

Benzene Ethylbenzene Isopropyl benzene

Methyl Tert Butyl Ether

Naphthalene 1,2,4-

Trimethylbenzene 1,3,5-

Trimethylbenzene Toluene Xylene (total) µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg

369215 5610419 8788084 42807198 578746 1370265 1222589 22111165 2602129

51000 250000 9900000 2100000 86000 1800000 1500000 47000000 2500000

SB1 (8-10) 4/3/2023 ND (67) 54.1 52.2 ND (13) ND (27) ND (13) ND (13) ND (13) ND (13)

SB2 (2-4) 4/3/2023 ND (67) 103 110 ND (13) 674 1310 818 ND (13) 198

SB3 (6-8) 4/3/2023 ND (1.3) ND (2.6) 0.92 J ND (2.6) 5.6 10.8 2.3 J ND (2.6) ND (2.6)

SB4 (4-6) 4/3/2023 5.4 J ND (13) 17.8 ND (13) ND (26) 6.9 J ND (13) ND (13) ND (13)

SB5 (10-12) 4/3/2023 ND (4.3) ND (8.6) 2.3 J ND (8.6) 14.3 J 43.2 10.2 ND (8.6) ND (8.6)

*: Surface and subsurface soil µg/kg - micrograms per kilogram

T1 RBSL = Tier 1 Risk-Based Screening Levels values to be established using North Dakota RBCA Technical Guidance

NA= not analyzed

ND (1.0) = constituent not detected above laboratory reporting limit (reporting limit in parentheses)

VOC analysis performed using EPA Method SW846 8260B

VOCs = Volatile Organic Compounds

Sample ID Date

Collected

T1 RBSL Construction Worker Soil* up to depth of construction

T1 RBSL

Commercial/Industrial

Surface Soil (0'-2')

Earth Systems, LLC

TABLE 2

SOIL - PAHs

M Gas Station T132N, R47W, Sec. 8 SWNW

Richland County, North Dakota

Acenaphthene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(k)fluoranthen e Chrysene

Ethylene dibromide (1,2- Dibromoethane)

Fluoranthene Fluorene Indeno(1,2,3-cd)pyrene 1-Methylnaphthalene 2-Methylnaphthalene Naphthalene Pyrene µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg µg/kg

NE NE NE NE NE NE NE NE NE NE NE NE NE NE NE

14988675 74943375 1736093 74475 1748635 17486347 174863474 34327 9992450 9992450 1748635 6029927 999245 578746 7494338

45000000 230000000 210000 21000 210000 2100000 21000000 N/A 30000000 30000000 N/A 730000 3000000 86000 23000000

SB1 (8-10) 4/3/2023 ND (92) ND (92) ND (92) ND (92) ND (92) ND (92) ND (92) ND (13) ND (92) ND (92) ND (92) ND (92) ND (92) ND (92) ND…