Document

EX-96.4 11 cmp-20210930xxex964goderic.htm EX-96.4 Document

Exhibit 96.4

Technical Report Summary

Salt Mineral Reserve Statement

Compass Minerals International, Inc.

Goderich Mine

Ontario, Canada

Effective Date: September 30, 2021

Report Date: November 29, 2021


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Signature

All data used as source material plus the text, tables, figures, and attachments of this document have been reviewed and prepared in accordance with generally accepted professional engineering and environmental practices.

This report, Salt Mineral Reserve Statement, was prepared by a Qualified Person.

/s/ Joseph Havasi

Joseph Havasi, CPG-12040

Director, Natural Resources

Compass Minerals International, Inc.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Table of Contents

Contents

Signature ii

List of Abbreviations ix

1 Executive Summary 1

2 Introduction 8

2.1 Registrant 8

2.2 Terms of Reference and Purpose 8

2.3 Sources of Information 8

2.4 Details of Inspection 8

2.5 Report Version 9

3 Property Description 10

3.1 Property Location 10

3.2 Property Area 11

3.3 Mineral Titles 12

3.3.1 History of Titles 12

3.4 Mineral Rights 13

3.5 Encumbrances 14

3.6 Other Significant Factor and Risks 14

3.7 Royalties Held 14

4 Accessibility, Climate, Local Resources, Infrastructure and Physiography 15

4.1 Topography, Elevation and Vegetation 15

4.2 Means of Access 16

4.3 Climate and Operating Season 17

4.4 Infrastructure Availability and Resources 17

5 History 18

6 Geological Setting, Mineralization and Deposit 19

6.1 Geologic Description 19

6.2 Mineral Deposit Type 19

6.3 Stratigraphic Section 20

7 Exploration 22

7.1 Procedures – Exploration Other than Drilling 22

7.2 Exploration Drilling 22


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

7.3 Procedures – Drilling Exploration 24

7.4 Characterization of Hydrology 24

7.5 Exploration – Geotechnical Data 26

7.6 Description of Relevant Exploration Data 27

8 Sample Preparation, Analyses and Security 29

8.1 Sample Preparation and Quality Control 29

8.2 Sample Analyses 29

8.3 Sample Quality Control and Assurance 29

8.4 Adequacy of Sample Preparation 29

8.5 Analytical Procedures 29

9 Data Verification 30

9.1 Data Verification Procedures 30

9.2 Conducting Verifications 30

9.3 Opinion of Adequacy 30

10 Mineral Processing and Metallurgical Testing 31

10.1 Nature and Extent 31

10.2 Degree of Representation 31

10.3 Analytical and Testing Laboratories 31

10.4 Recovery Assumptions 31

10.5 Adequacy of Data 33

11 Mineral Resource Estimate 34

11.1 Introduction 34

11.1.1 Key Assumptions and Parameters 34

11.1.2 Methodology 35

11.2 Mineral Resource Statement 35

11.3 Estimates of Cut-off Grades 36

11.4 Resource Classification 36

11.5 Uncertainty of Estimates 38

11.6 Multiple Commodity Grade Disclosure 39

11.7 Relevant Technical and Economic Factors 39

12 Mineral Reserve Estimates 40

12.1 Introduction 40

12.2 Mineral Reserve Statement 40


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

12.3 Estimates of Cut-off Grades 41

12.4 Reserve Classification 41

12.5 Multiple Commodity Grade Disclosure 41

12.6 Risk of Modifying Factors. 42

13 Mining Methods 43

13.1 Geotechnical and Hydrological Models 47

13.2 Production Schedule 49

13.3 Requirements for Stripping, Underground Development and Backfilling 51

13.3.1 Stripping 51

13.3.2 Underground Development 51

13.3.3 Backfilling 52

13.4 Mining Equipment, Fleet and Personnel 52

14 Processing and Recovery Methods 54

14.1 Process Description 54

14.2 Waste Handling 58

14.3 Power and Natural Gas Consumption 58

14.4 Personnel 58

15 Infrastructure 59

15.1 Roads 59

15.2 Electricity 60

15.3 Natural Gas 60

15.4 Water 60

15.5 Rail 61

15.6 Navigation 61

15.6.1 North River Wall 61

15.6.2 South and North Piers 62

15.6.3 North and South Breakwaters 62

15.6.4 Lake Shipping Traffic 62

16 Market Studies 64

16.1 General Marketing Information 64

16.2 Material Contracts Required for Production 66

17 Environmental, Social and Permitting 67

17.1 Results of Environmental Studies and Baselines 67


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

17.2 Waste, Tailings and Water Plans – Monitoring and Management 67

17.3 Project Permitting Requirements 67

17.3.1 Air Permit 67

17.3.2 Surface Water Effluent Discharge Permit 67

17.4 Plans Negotiations or Agreements (Environmental) 68

17.5 Mine Closure Plans 68

17.6 Adequacy Assessment of Plans 68

17.7 Local Hiring Commitments 68

18 Capital and Operating Costs 69

18.1.1 Capital Costs 69

18.1.2 Operating Cost 69

18.1.3 Assumptions 73

18.1.4 Accuracy 73

19 Economic Analysis 74

19.1.1 Operating Costs 74

19.1.2 Capital Costs 74

19.1.3 Economic Analysis 82

19.1.4 Sensitivity Analysis 82

20 Adjacent Properties 84

21 Other Relevant Data and Information 85

22 Interpretation and Conclusions 86

22.1 Mineral Resource 86

22.2 Mineral Reserves 86

22.3 Financial 87

23 Recommendations 88

23.1 Geology and In-Seam Seismic 88

23.2 Costs 88

24 References 89

25 Reliance on Information Provided by the Registrant 90

26 Date and Signature Page 91


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

List of Tables

Table 1-1: Goderich Mine – Summary of Salt Mineral Resources at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020 4

Table 1-2: Goderich Mine – Summary of Salt Mineral Reserves at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020 4

Table 2‑1: Site Visits. 9

Table 6‑1: Thickness of A-2 Salt in Exploration Drilling. 20

Table 7‑1: Typical Borehole Log Near Shafts at Goderich Mine. 24

Table 7-2: Geologic Conditions Identifed During Shaft Sinking. 25

Table 7-3: Hydrogeologic data from Test Well VWP-1. 25

Table 7-4: Drill Hole Locations. 27

Table 11‑1: Goderich Mine – Summary of Salt Mineral Resources at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020. 35

Table 12‑1: Goderich Mine – Summary of Salt Mineral Reserves at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020. 40

Table 13‑1: Summary of Rock Properties. 47

Table 13‑2: Summary of Comparison between New Three-Room Layout Performance and Current Regional Pillar Layout 48

Table 13‑3: Summary of key assumptions in the definition of the Goderich Reserves. 51

Table 13‑4: Table of Equipment Used in the Mining Method. 53

Table 14-1: Summary of Mine Processing Equipment 56

Table 14-2: Summary of Electricity and Natural Gas Consumption. 58

Table 14-3: Summary of Personnel Employed. 58

Table 16‑1: World Forecast Demand for salt by region. 64

Table 16‑2: US and Canada: Prodcution, trade, and apparent consumption of salt, 2010-2019 (kt) 65

Table 16‑3: USGS Summary of Salt Pricing. 65

Table 16‑4: Summary of Goderich Mine Production and Sales by Segment 65

Table 18-1: Summary of Capital and Operating Costs: 2017-2021. 70

Table 18-2: Summary of Capital Expenses through 2026. 71

Table 19-1: Life of Mine Cash Flow Analysis. 76

Table 19-2: Sensitivity Analysis: Cost Factors. 82

Table 19-3: Sensitivity Analysis: Price. 83

Table 23-1: Summary of Annual Costs for Recommended Work 89


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

List of Figures

Figure 3-1: Site Location Map 10

Figure 3-2: Aerial View of Mine Site and Extent of Mineral Lease 11

Figure 3-3: Extent of Mine Site 12

Figure 3-4: Goderich Mine Salt Lease Water Lots 13

Figure 4-1: Goderich Harbor 15

Figure 4-2: Topographic Quadrangle Map: Goderich Mine 16

Figure 6-1: General Cross Section of Michigan Basin 20

Figure 6-2: Stratigraphic Sequence of the Michigan Basin and the Goderich Salt Mine 21

Figure 7-1: Exploration Drilling and In-seam Seismic Surveys at the Goderich Salt Mine 23

Figure 7-4: Drill Hole Locations 27

Figure 10-1: Standard QC Report for key Testing Parameters for Highway Deicing Salt 32

Figure 10-2: 303 Highway Salt Fines (%28 Mesh) Performance 33

Figure 11-1: Resource Classification Domains 38

Figure 13-1: Representation of Room and Pillar Mining 44

Figure 13-2: Salt Mining Cycle Fowchart 45

Figure 13-3: Mining Layout Near Shaft Locations 45

Figure 13-4: Layout of Current Mining Extents 46

Figure 13-5: Goderich Mine Long-Term Production Layout 50

Figure 14-1: Mining Process Flow Chart 55

Figure 15-1: Overview of Goderich Harbor Infrastructure 59

Figure 15-2: Goderich Harbor Navigational Infrastructure 63

Figure 16-1: Roskill Deicing Salt Forecast through 2028 66


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

List of Abbreviations


Abbreviation			Unit or Term
%			percent
~			approximately
°			degree
AuEq			gold equivalent
C$			Canadian dollar(s)
EA			Environmental Assessment
EIS			environmental impact statement or environmental impact study
ft			foot or feet
g			Gram
G&A			general and administrative
g/t			grams per ton
gpm			gallons per minute
GSL			Great Salt Lake
h or hr			hour(s)
koz			thousand ounces
kt			thousand tons
L/s			liters per second
lb			pound or pounds
Mg/L			Milligrams per liter
min			minute
Mt			million tons
sec			second
SMU			selective mining unit
SRM			standard reference material
STM			short term modeling
t			ton(s) (2,000 lb)
t/d			tons per day
t/h			tons per hour
t/y			tons per year
TSF			tailings storage facility
US$			United States Dollar
y or yr			Year


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

1Executive Summary

The Goderich mine is a production stage, underground mine that produces rock salt primarily for highway deicing use and as feed product for other uses. The Goderich mine is located west of the town of Goderich, Ontario, on an isthmus in the mouth of the Maitland River, as it enters Lake Huron.

The Goderich mine is approximately 60 miles northwest of London, Ontario, and 120 miles west of Toronto, Ontario. Its approximate coordinates are 43˚ 44’ 50” North and 81˚ 43’ 30” West. Access to the Goderich mine is considered excellent. The town of Goderich has established infrastructure for both mining and exporting salt and can be accessed via regional highways from Toronto from the east (2.5 hours). The triangular-shaped mine site is surrounded by the lake on three sides and the Maitland River on the north side. Goderich Harbor and the Goderich mine site are accessed via North Harbor Road, a municipally owned and maintained road that connects the harbor area to Highway 21. The Goderich mine is connected to local power, water, natural gas and sewage infrastructure. Primary logistics for transporting mined product include the rail siding at the mine site and direct loading into ships or barges in Goderich Harbor. The town of Goderich provides all necessary resources for the Goderich mine, with a ready labor supply, housing, hotels, food and all other typical facilities. The close proximity to rail, port and roads provides easy access for all logistical needs.

The Goderich mine site is located on 16.3 acres of Company-owned land on a man-made peninsula consisting of several large buildings and silos associated with mining and material handling, a ship loading facility and three shafts. The Company actively mines salt west of its owned land under Salt Mining Lease No. 107377, dated November 9, 2001, with the Ontario Ministry of Energy, Northern Development and Mines, comprising approximately 13,195 acres. The lease has a 21-year term expiring on May 31, 2022. The Company has an option to renew the lease for an additional 21 years, until 2043, so long as the Company can demonstrate that the Goderich mine’s useful life extends through the 21-year renewal term, which the Company expects to exercise. The only material payments associated with the lease are royalties on the salt produced. The current royalty rate paid is $1.05 / ton.

The Goderich mine’s underground infrastructure is situated in the A-2 salt bed approximately 1,750 feet to 1,760 feet below the surface at the mine shafts’ location. The A-2 salt bed in the shaft area is approximately 79 feet thick. The regional stratigraphic sequence is well understood from many wells drilled across the basin and locally in the Goderich, Ontario, area. The salt strata are highly continuous over the basin, and most of the major salt units can be traced for hundreds of miles. On a local scale, the continuity of the salt beds can be impacted by the presence of pinnacle reefs, displacement by faults, or the local leaching of salt. The Company can use various tools to characterize geological conditions in nearby areas to assess the possibility of encountering these local ground conditions at the mine. Accordingly, the Company has engaged third parties to conduct in-seam seismic surveys and, more recently, has begun use of ground penetrating radar and in-seam directional drilling techniques to identify disturbances in salt continuity and the thickness of the A-2 salt bed in development.

The Goderich mine has procured and is operating in compliance with all required operating licenses, including permits pertaining to mineral extraction, effluent discharge and air permitting. The Ontario Ministry of Energy, Northern Development and Mines regulates closure for the Goderich mine. The most recent closure plan was approved by the ministry in 2012, and is in process of being amended


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

as of September 30, 2021. Long-term cleanup of the site will essentially include demolishing surface facilities, removal of surface infrastructure and restoring a natural alvar ecological community on the surface, flooding of the workings, and decommissioning (plugging). The Goderich mine operates under two air permits issued by the Ontario Ministry of Environment, Conservation and Parks, one for the lab (8-1131-96-007), and the other for the garage for welding exhaust (5522-78NUN2). Site drainage into Snug Harbour and the Maitland River is permitted pursuant to Certificate of Approval 2342-7ULQEU and Environmental Compliance Approval 1236-8YGK8A, respectively, issued by the Ontario Ministry of Environment, Conservation and Parks.

The Goderich mine progresses development of main entries in advance of bench mining. The subsequent benches achieve the remainder of the 60-foot room height for room production. Development and bench mining progress at an approximate 40:60 ratio in terms of area of advance in the mine plan and are part of the production process. As needed, underground rooms for facility support functions have been and will be developed in excavated areas of the mine. This includes development of shaft areas on each level for hoist equipment, design, planning and development of ramp structures from one level to the subsequent, lower level as required, installation of underground work facilities such as maintenance shops and storage rooms. As mining progresses, development also encompasses the design, placement, repair and maintenance of support infrastructure such as crushers, screens and other plant in support of mining. All portions of mine development within the A-2 salt are planned to be operated in the same manner and mining method, with the same mining parameters and with the same set of unit operations.

The general method of mining employed at the Goderich mine is known as room and pillar mining. Beginning in 2012 and 2013, the Company advanced the Goderich mine to mechanized room and pillar mining as continuous miners (each a “CM”) replaced the previous under-cutter/over-cutter equipment and drilling and blasting sequence in the development areas of the mine. By 2017, the Company was engaged in continuous mining of the entire 60-foot face of the mined rooms in multiple lifts with a goal of improving efficiency, reducing costs and reducing the amount of diesel equipment utilized underground, thus largely eliminating the use of drilling and blasting at the Goderich mine. The Company continues to upgrade its CM fleet at the Goderich mine.

Certain mining units at the Goderich mine are equipped with both a CM and a flexible conveyor train (“FCT”), a dynamic move-up unit and a belt storage unit. On these mining units, the CM cuts the salt directly from the face and discharges it into a hopper on the end of the FCT. From the FCT, the rock salt is offloaded to the main underground belt conveyance system where it is then transported to the underground crushers and the mill. Other mining units are also equipped with a CM, but are supported with rubber-tired haulage equipment to transfer salt. Salt mined from these CMs is transferred from the face by rubber-tired haulage to a centralized dump point with a crusher and then follows the same process as the other units once the salt is put onto the underground conveyance system. Rock salt is processed and sized at the underground crushers and the mill before being hoisted to the surface. Salt is stockpiled at the surface in domes and it then may be treated with yellow prussiate of soda (“YPS”), depending on the end use of the salt. The salt is then distributed to depots, packaging facilities and customers via ship (approximately 80%), and rail car and truck (approximately 20%).

All of the surface exploration at Goderich mine occurred during the 1950’s. The drilling results were summarized by Kenneth K. Landes in a report titled Report on Rock Salt Reserves at Goderich, Ontario, dated March 30, 1957. The Landes report concluded the A-2 salt had an average NaCl


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

content of 98.17%. The report does not indicate the tests performed, if the samples were composited or any specific detail of how analytical testing and sample handling were performed. However, the purities described in the Landes report are indicative of the purity levels found within the mine.

The salt resources at Goderich mine have been estimated in conformity with Items 601(b)(96) and 1300 through 1305 of Regulation S-K promulgated by the SEC generally accepted industry practice. The resource estimates are compiled utilizing data and experience of the geological continuity of the salt deposit gained over approximately 65 years of mining the A-2 salt bed, as well as the information gathered from 10 vertical core boreholes drilled in the 1950s in the salt bed.

The resulting models provide an estimate of the total resource available to Compass Minerals as defined. In compiling a resource estimate for the Goderich mine, several key assumptions were made:

•Mineral resources are not mineral reserves and do not have demonstrated economic viability,

•Underground mineral resources were initially reported based on the established mining practices, including the established 56-foot mining horizon (mining height). The mining height of 60 feet is proposed, being incorporated, and is utilized for estimates,

•The 60-foot mining height is based upon locational experience, practical fit and execution of mining practices, and past studies and recommendations regarding ground control and roof support performed,

•The proposed mining height at Goderich is under review and may vary in the future,

•The specific point of reference for Goderich mine is constrained to the current elevation of the salt bed on the lease at the base of the A-2 salt, approximately 1,750 ft to 1,760 ft below ground surface at the mine shaft location. Mining occurs within the 82-foot thick A-2 salt bed and is limited within the existing leases as described in the paragraphs in Section 3,

•All values have been rounded to reflect the relative accuracy of the estimates, and

•Tonnage was calculated based on a tonnage factor of 0.0675 tons/ft3.

The resource estimation methodology involved the following procedures:

•Review of available data and reports,

•Database compilation and verification,

•Definition of resource domains,

•Volumetric calculation based on A-2 salt bed assumptions,

•Resource classification and validation,

•Assessment of “reasonable prospects for economic extraction”, and

•Preparation of the Mineral Resource Statement.

Summaries of the Goderich mine’s salt mineral resources and mineral reserves as of September 30, 2021 and December 30, 2020 are shown in Tables 1-1 and 1-2, respectively. Joseph Havasi, who is


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

employed full-time as the Director, Natural Resources of the Company, served as the QP and prepared the estimates of salt mineral resources and mineral reserves at the Goderich mine.

Table 1-1. Goderich Mine – Summary of Salt Mineral Resources at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020.


	Salt Resource (tons)(1)(2)(4)(5)(6)(7)(8)
Resource Area(3)(9)	As of September 30, 2021	As of December 31, 2020
Measured Resources	—	—
Indicated Resources	1,485,710,000	1,503,121,000
Measured + Indicated Resources	1,485,710,000	1,503,121,000
Inferred Resources	148,200,000	148,200,000

(1) Mineral resources are not mineral reserves and do not have demonstrated economic viability.

(2) All figures have been rounded to reflect the relative accuracy of the estimates.

(3) Underground mineral resources are reported based on an expected representative A-2 salt bed thickness of 82 feet.

(4) Tonnage was calculated based on a tonnage factor of 0.0675 tons per cubic foot

(5) Included process recovery is 97.5% based on production experience. Included mining recovery is approximately 38.7% based on the room and pillar mine plan.

(6) Although the actual sodium chloride grade is less than 100%, it is not considered in the reserve as the final saleable product is the in situ product, as-present after processing (i.e., the saleable product includes any impurities present in the in situ rock).

(7) A cut-off grade was not utilized for the calculation as the in situ product quality is relatively constant and saleable after processing.

(8) There are multiple saleable products based on salt quality from the operation (rock salt for road deicing and chemical grade salt). For simplicity, all sales are assumed at the lower value (and higher tonnage) product, rock salt, and are based on pricing data described in Section 16 hereof. The pricing data is based on a five-year average of historical gross sales data for rock salt for road deicing of $60.58 per ton. Gross sales prices are projected to increase to approximately $295.60 per ton for rock salt for road deicing through year 2094 (the current expected end of mine life).

(9) Based on an area of approximately 575,257,000 square feet for the A-2 salt bed within the lease area.

Table 1-2. Goderich Mine – Summary of Salt Mineral Reserves at the End of the Fiscal Years Ended September 30, 2021 and December 30, 2020.


	Salt Reserve (tons)(1)(2)(3)(4)(5)(6)(7)(8)
Reserve Area(3)(9)	As of September 30, 2021	As of December 31, 2020
Proven Reserves	—	—
Probable Reserves	470,030,000	476,768,000
Total Reserves	470,030,000	476,768,000

(1) Ore reserves are as recovered, saleable product.

(2) All figures have been rounded to reflect the relative accuracy of the estimates.

(3) Reserve volume assumes a mining thickness of 18 meters (approximately 60 feet) production, 8.5 meters (approximately 28 feet) mains.

(4) Tonnage was calculated based on a tonnage factor of 0.0675 tons per cubic foot.

(5) Included process recovery is 97.5% based on production experience. Included mining recovery is approximately 38.7% based on the room and pillar mine plan.

(7) A cut-off grade was not utilized for the calculation as the in situ product quality is relatively constant and saleable after processing.

(8) There are multiple saleable products based on salt quality from the operation (rock salt for road deicing and chemical grade salt). For simplicity, all sales are assumed at the lower value (and higher tonnage) product, rock salt and are based on pricing data described in Section 16 hereof. The pricing data is based on a five-year average of historical gross sales data for rock salt for road deicing of $60.58 per ton. Gross sales prices are projected to increase to approximately $295.60 per ton for rock salt for road deicing through year 2094 (the current expected end of mine life).

(9) Based on an area of approximately 575,257,000 square feet for the A-2 salt bed within the lease area.

Capital and operating costs were developed on a unit cost and quantity basis utilizing the QP’s estimates that are based on owner’s costs from the past five years, current and historic cost data from continuous and ongoing operation of the facility, first principles, and 65 years of operational


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

experience operating the facility at projected production run rates. Operating costs presented herein are the QP’s estimates based on the understanding of actual owner’s costs incurred at the operation since 2017, vendor/contractor quotations, and similar operation comparisons, while capital costs projected through 2026 are estimates by the QP based on owner’s cost estimates developed based on unit cost and quantity basis utilizing historic cost data, first principles, vendor/contractor quotations, and similar operation comparisons.

The average annual capital expenditure since 2017 at the Goderich mine is $37,172,000, with a high of $56,984,000 in 2017 and a low of $17,999,000 in the nine-month 2021 fiscal year. The higher than average capital spend in 2017 was primarily associated with a shaft-lining project that was undertaken for safety and maintenance of business. A summary of capital expenses incurred from 2017 through 2021 by the owner is provided in Table 18-1.

The Goderich mine, as well as all Compass Minerals facilities, maintains a five-year capital forecast for all foreseen capital expenditures to support current production. A summary of foreseen capital expenditures is provided on Table 18-2. As shown on Table 18-2, total estimated capital expenditure through 2026 is $189,691,000, and is comprised of either MOB capital and capital spend for major foreseen capital projects through 2026 including:

•Construction of a new Mill and new egress / ingress from Mill to shaft for $44,687,000.

•Maintenance, replacement and rebuilds of the fleet of Continuous Miners for $78,499,000.

The balance of the forecasted capital expenditure through 2026 is $66,506,000 and primarily includes routine replacement for mine vehicles and equipment. Listed expenditures are based on cost estimates generated by third parties, within +/-15% level of accuracy. There are risks regarding the current capital costs estimates through 2026, including escalating costs of raw materials and energy, equipment availability and timing due to either production delays or supply chain gaps.

Actual operating costs incurred at the Goderich mine from 2017 through 2020 are provided in Table 18-2. Summarized costs include labor, maintenance, supplies electric, diesel, lease royalties, logistics and taxes.

Since 2016, total operating costs per ton have ranged from $32.00 per ton in 2021 to $51.30 in 2018 (impacted by a strike). A 66% increase in hoisted tons over the period is the primary factor in the resulting decrease in cost per hoisted ton, as well as efficiencies realized from the exclusive operation of CMs and what is viewed as an equitable CBA with labor at the Mine.

Excluding impacts associated with mining inefficiency associated with ramp development, the mine has realized a 4% increase headcount from 509 to 530 employees since 2017.

The Goderich mine has a long history of mining salt from the A2 salt deposit. This history includes a wealth of knowledge on how the ore behaves during mining, quality of the ore, the geomechanical properties of salt to enable safe and sustainable mining practices.

The modeling and analysis of the Company’s resources and reserves has been developed by Company mine personnel and reviewed by several levels of internal management, including the QP. The development of such resources and reserves estimates, including related assumptions, was a collaborative effort between the QP and Company staff.

The Company’s salt-producing locations do not utilize classic exploration techniques in the development of their assumptions around mineral resources or reserves. The mineral deposit at


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Goderich is restricted in access by bodies of water, and industry techniques used for geological exploration for other types of mineral deposits, specifically collection of rock core from drilling, can be degradational to the salt ore being assessed. Given the nature of the salt mineral and each site’s beneath a massive water body, this limitation impedes the validation of mineral resources and reserves using exploration drilling techniques. Accordingly, geophysical techniques are utilized at Goderich to assist in mine planning, and to verify that there are no obstructions ahead of advancement of the mine in the form of geological anomalies or structural features, such as faults that could affect future mining. In conducting these geophysical campaigns, including in-seam seismic and ground penetrating radar technologies, the Company is able to identify the continuity of ore-body ahead of mining. In-seam directional drilling is also conducted at Goderich as a means of extending our visibility into the ore body beyond the ranges that can be assessed by geophysical technologies.

Geological modeling and mine planning efforts serve as a base assumption for resource estimates at each significant salt-producing location. These outputs have been prepared by both Company personnel and third-party consultants, and the methodology is compared to industry best practices. Mine planning decisions, such as mining height, execution of mining and ground control, are determined and agreed upon by Company management. Management adjusts forward-looking models by reference to historic mining results, including by reviewing performance versus predicted levels of production from the mineral deposit, and if necessary, re-evaluating mining methodologies if production outcomes were not realized as predicted. Ongoing mining and interrogation of the mineral deposit, coupled with product quality validation pursuant to industry best practices and customer expectations, provides further empirical evidence as to the homogeneity, continuity and characteristics of the mineral resource. Ongoing quality validation of production also provides a means to monitor for any potential changes in ore-body quality. Also, ongoing monitoring of ground conditions within the mine, surveying for evidence of subsidence and other visible signs of deterioration that may signal the need to re-evaluate rock mechanics and structure of the mine ultimately inform extraction ratios and mine design, which underpin mineral reserve estimates.

The Company assesses risks inherent in mineral resource and reserve estimates, such as the accuracy of geophysical data that is used to support mine planning, identify hazards and inform operations of the presence of mineable deposit. Also, management is aware of risks associated with potential gaps in assessing the completeness of mineral extraction licenses, entitlements or rights, or changes in laws or regulations that could directly impact the ability to assess mineral resources and reserves or impact production levels.

Notwithstanding, the salt deposit supports continued successful exploitation, given the size, grade, metallurgical characteristics, developed infrastructure, and the knowledge and experience of the individuals engaged in the project. The uncertainty and risk associated with the historic exploration data can be mitigated where possible, through annual in-seam seismic campaigns, application of ground penetrating radar, and in-seam directional validation drilling.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Sensitivity analyses conducted on the life-of-mine cash flow analysis indicates that this is a robust project that can withstand 20% increases in the key cash flow components:

•If mining operating costs were to increase 20% from those currently estimated, the project would still remain viable by interpolation of the sensitivities shown in Table 19-2.

•If capital construction costs were to increase 20% from those currently estimated, the project would still remain viable by interpolation of the sensitivities shown in Table 19-2.

•The facility can also withstand a decrease in average selling price of 20% from those currently estimated according to the sensitivities shown in Table 19-3.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

2Introduction

2.1Registrant

This Technical Report Summary (this “TRS”) was prepared in accordance with Items 601(b)(96) and 1300 through 1305 of Regulation S-K (Title 17, Part 229, Items 601(b)(96) and 1300 through 1305 of the Code of Federal Regulations) promulgated by the Securities and Exchange Commission (“SEC”) for Compass Minerals International, Inc. (“Compass Minerals” or the “Company”) with respect to estimation of salt mineral reserves for Compass Minerals’ existing operation producing salt in Goderich, Ontario, Canada (referred to as the “Goderich Mine”, “Goderich mine” or the “Mine”).

2.2Terms of Reference and Purpose

The quality of information, conclusions, and estimates contained herein are based on: i) information available at the time of preparation and ii) the assumptions, conditions, and qualifications set forth in this TRS.

Unless stated otherwise, all volumes and grades are in U.S. customary units and currencies are expressed in constant third quarter 2021 U.S. dollars. Distances are expressed in U.S. customary units.

The purpose of this TRS is to fulfill the requirements of a Mineral Reserve Assessment for the Goderich Mine.

The effective date of this Technical Report Summary is September 30, 2021.

2.3Sources of Information

This TRS is based upon technical information and engineering data developed and maintained by local personnel at the Goderich Mine site, Compass Minerals’ corporate supporting resources and from work undertaken by third-party contractors and consultants on behalf of the mine. In addition, public data sourced from the Goderich Port Management Commission, Huron County GIS, internal Compass Minerals technical reports, previous technical studies, maps, Compass Minerals letters and memoranda, and public information as cited throughout this TRS and listed in Section 24, “References,” and 25, “Reliance on Information Provided by the Registrant.”

This report was prepared by Joseph R. Havasi, MBA, CPG-12040, a qualified person.

2.4Details of Inspection

The following table summarizes the details of the personal inspections on the property by the qualified person.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary


QP	Date(s) of Visit	Details of Inspection
Joe Havasi	August 2010 – August 2020	Mr. Havasi visited the site in support of miscellaneous projects and met with Site, Engineering, and Financial Management over a period of ten years. Visits and meetings at the site and with Town leaders regarding Mine Closure Plan, completion of the Mine Closure Plan, and leasing matters.
Joe Havasi	August 2021	Mr. Havasi visited the site in support of completion of the Mine Closure Plan, miscellaneous projects and met with Site, Engineering, and Financial Management to procure information for use in this TRS.
Joe Havasi	September 2021	Mr. Havasi visited the site in support of miscellaneous projects and met with Site, Engineering, and Financial Management.

Table 2-1: Site Visits

2.5Report Version

This TRS is not an update of a previously filed TRS.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

3Property Description

The Goderich mine is a production stage, underground mine that produces rock salt primarily for highway use and as feed product for other uses. The Goderich mine is located in southwestern Ontario, Canada, on the eastern shore of Lake Huron. The Goderich mine is located west of the town of Goderich, Ontario, on an isthmus in the mouth of the Maitland River, as it enters Lake Huron. The Goderich mine location is shown in Figure 3-1, while Figure 3-2 illustrates the juxtaposition of owned land where the mine site is located with Compass Minerals salt lease.

Figure 3-1: Site Location Map

3.1Property Location

The Goderich mine is approximately 60 miles northwest of London, Ontario, and 120 miles west of Toronto, Ontario. Its approximate coordinates are 43˚ 44’ 50” North and 81˚ 43’ 30” West.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Source: Compass, 2012 (Mine Closure Plan)

Figure 3-2: Aerial View of Mine Site and Extent of Mineral Lease

3.2Property Area

The mine site includes approximately 16.3 Company-owned acres of man-made peninsula consisting of several large buildings and silos associated with mining and material handling, a ship loading facility and three shafts. Compass Minerals owns the surface and mineral rights shown on Figure 3-3. Compass Minerals actively mines salt west of its owned land under a salt lease with the Ministry of Energy, Northern Development and Mines (ENDM)(lease #107377) comprising approximately 13,195 acres (Figure 3-1).


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Source: Compass, 2012 (Mine Closure Plan)

Figure 3-3: Extent of Mine Site

3.3Mineral Titles

3.3.1History of Titles

Salt production began in Goderich, Ontario, in 1867 by Sifto Canada (“Sifto”), after an unsuccessful search for oil uncovered a vast bed of rock salt. Sifto used basic solution mining and evaporation, now known as mechanical evaporation, to begin the nearby Goderich plant.

Salt exploration was initiated in the area in the early 1950s. That exploration targeted a potential underground mining operation started in the Goderich Harbor area. However, prior to that, a narrow peninsula had been constructed for use as a trunk line for the CN Railway. Further, the Department of Transport operated a small marina on the south east side of what was to become the mine lease which, at that time, was only accessible by water. The peninsula was widened and the area to be used by the mine and neighboring facilities was constructed using materials from local quarries and supplemented with materials from the first mine shaft.

In 1956, Sifto received approval to operate an underground salt mine while under the ownership of Dominion Tar and Chemical Company Ltd. Initial drilling at the Goderich mine started in 1955 with the sinking of the first shaft beginning in 1957. The Goderich mine started production upon the completion of the first shaft in 1959. Additional increases in production were enabled after a second mine shaft and a third mine shaft were completed in 1962 and 1982, respectively. In 1990, Domtar Chemicals Limited (previously known as Dominion Tar and Chemical Company Ltd.) sold Sifto to the North American Salt Company, a subsidiary of D.G. Harris & Associates (“DGHA”). In 1993, DGHA founded Harris Chemical Group as a holding company for salt operations which was acquired by IMC Global (“IMC”) in 1997. IMC sold a majority of its salt operations, including the Goderich mine, to Apollo Management V, L.P. through an entity called Compass Minerals Group in 2001. Following a


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

leveraged recapitalization, the company now known as Compass Minerals International, Inc. completed an initial public offering in 2003.

3.4Mineral Rights

The Goderich mine site is located on 16.3 acres of Company-owned land (PIN 41369-0004) on a man-made peninsula consisting of several large buildings and silos associated with mining and material handling, a ship loading facility and three shafts. The Company actively mines salt west of its owned land under Salt Mining Lease No. 107377, dated November 9, 2001, with the Ontario Ministry of Energy, Northern Development and Mines, comprising approximately 13,195 acres. The lease has a 21-year term expiring on May 31, 2022. The Company has an option to renew the lease for an additional 21 years, until 2043, so long the Company can demonstrate that the Goderich mine’s useful life extends through the 21-year renewal term, which the Company expects to exercise. The only material payments associated with the lease are royalties on the salt produced. The current royalty rate paid is $1.05 per ton.

There are three Water Lot Locations that comprise the overall Salt Mining Lease:

•CL 3803, covering 1,058.3 hectares,

•CL 3804 covering 1,269.6 hectares and

•CL 9861 covering 3,012.2 hectares.

These three Water Lots total 5,340.1 hectares.

Figure 3-4 shows the individual Water Lots comprising the overall Salt Lease.

Source: Archibald, Gray & McKay (Ontario Land Surveyors), 1996

Figure 3-4: Goderich Mine Salt Lease Water Lots


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

3.5Encumbrances

The Mine is not subject to known encumbrances in the form of future permitting requirements, permit conditions, violations or fines.

Notwithstanding, the QP is aware of an aboriginal land claim filed in 2003 by The Chippewas of Nawash and The Chippewas of Saugeen (the “Chippewas”) in the Ontario Superior Court against The Attorney General of Canada and Her Majesty The Queen In Right of Ontario. The Chippewas claim that a large part of the land under Lake Huron was never surrendered by treaty and thus seek a declaration that the Chippewas hold aboriginal title to those submerged lands. The land to which aboriginal title is claimed includes land under which our Goderich mine operates and has mining rights granted to it by the government of Ontario. The actions also seek damages for the value and loss of use of lands. The Company is not a party to the court actions. On July 29, 2021, the Court in Ontario issued an order holding that the Chippewas do not have aboriginal title to the submerged lake lands. The Chippewas subsequently appealed that ruling, and the appeal is still pending.

3.6Other Significant Factor and Risks

All significant factors or risks have been identified and described in the TRS.

3.7Royalties Held

Not Applicable.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

4Accessibility, Climate, Local Resources, Infrastructure and Physiography

4.1Topography, Elevation and Vegetation

The Goderich Mine surface facility is situated on ‘made-land’ that was created in 1872, following the redirection and dredging of the Maitland River, north to its current alignment, and the construction of a breakwater separating the river mouth from the harbor. Construction of the north and south piers was also undertaken in 1872, with north and south breakwaters being constructed between 1904 and 1908, and extended in 1911 (GPMC, 2014) (Figure 4-1). The elevation of the Goderich Mine is 179m amsl, and is bounded by the Maitland River to the north, Lake Huron to the west, the Goderich Harbor and Snug Harbor to the south and east. The entire site is very gently sloping to the southwest (Figure 4-2).

Figure 4-1: Goderich Harbor

Source: Compass Minerals

The datum elevation of Lake Huron is 176 meters (IGLD, 1985). Maximum and minimum water levels range from 175.6 m to 177.5 m above sea level (ASL), as reported by International Great Lakes Datum (IGLD) 1985. The long-term average lake level is established at 176.5 m ASL.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Figure 4-2: Topographic Quadrangle Map: Goderich Mine

Source: Compass Minerals

Although species diversity was relatively high in the areas associated with the Lower Maitland River Valley, the harbor area has been heavily influenced by human activity, including the creation of much of the harbor’s infrastructure; consequently, there is very little vegetation at the mine site. The Town of Goderich is located in the Physiographic Region known as the Huron Slope. This is a narrow strip of land between the Wyoming Moraine and the eastern shoreline of Lake Huron. The Huron Slope extends from Sarnia to Tobermory and is characterized by a number of dominant landforms including spillways, till plains, kame moraines, beach ridges, sand dunes and shore cliffs. The Huron Slope is considered to be a clay plain of glacial Lake Warren overlying a fine-grained (i.e. primarily silt and clay sized particles) basal glacial till. Till is sometimes exposed at the surface and thin surficial layers of sand are found in the immediate area of Goderich (Golder 2012).

4.2Means of Access

Access to the Goderich mine is considered excellent. The town of Goderich has established infrastructure for both mining and exporting salt and can be accessed via regional highways from Toronto from the east (2.5 hours). The triangular-shaped mine site is surrounded by the lake on three sides and the Maitland River on the north side. Goderich Harbor and the Goderich mine site are accessed via North Harbor Road, a municipally owned and maintained road that connects the harbor area to Highway 21. Commercial air travel is available from London, Ontario, Toronto, Ontario, and Detroit, Michigan, all of which are in relative proximity to the site.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

4.3Climate and Operating Season

The Town of Goderich is located on the windward side of Lake Huron, approximately 120 km north of Sarnia, which is at the southern end of the lake. Goderich’s climate is moderated by its proximity to Lake Huron with a summer daytime average temperature of 17.75oC and a winter daytime average temperature of -4.75oC. Goderich receives a monthly average of 90.25 mm of rain during the summer and a monthly average of 74.75 cm of snow during the winter (Environment Canada 2012).

4.4Infrastructure Availability and Resources

The Operation is connected to local power, water, natural gas and sewage infrastructure. Primary logistics for transporting mined product include the rail siding and direct loading into ships or barges in Goderich Harbor.

The town of Goderich provides all necessary resources for the Operation with a ready labor supply, housing, hotels, food and all other typical facilities. The close proximity to rail, port and roads provides easy access for all logistical needs.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

5History

The following history of Goderich Harbor was derived from the Goderich Port Management Corporation’s Environmental Assessment in support of potential port expansion project:

Since the 1820’s Goderich has had an active harbor associated with lumber and agricultural produce (InterVISTAS 2009). The area surrounding Goderich’s natural harbor was surveyed by the Canada Company in 1827, with a trading post established at the mouth of the Maitland River by 1828. Between 1830 and 1850 the Canada Company built two wooden piers to protect vessels in the harbor from storms (Heritage Resources Centre 2010). Today’s modern harbor was created in 1872, following the redirection and dredging of the Maitland River, north to its current alignment, and the construction of a breakwater separating the river mouth from the harbor. Construction of the north and south piers was also undertaken in 1872, with north and south breakwaters being constructed between 1904 and 1908, and extended in 1911 (Heritage Resources Centre 2010).

The Goderich Port became a favorite wintering spot for schooners and other ships. Between 1840 and 1962, over 100 vessels were built in the harbor. The first grain elevator at the Port was built in 1866 but was later destroyed by fire. The current elevators, constructed in the 1920s, are still in operation today. In 1866, Samuel Platt discovered salt while drilling for oil in the harbor.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

6Geological Setting, Mineralization and Deposit

6.1Geologic Description

The Goderich Salt Mine is located near the east edge of the Michigan salt basin (Figure 6-1). The stratigraphy consists of a sedimentary rock sequences which includes salt evaporates (or halites) contained within the Silurian-age Salina formation (Figure 6-2). The Silurian dolomites, shales, and evaporites are overlain by the dolomites and limestones of Devonian-age and underlain by Ordovician limestones and shales. The Salina group is classified into units in ascending order from A to G.

The sediments of the Salina formation approach 3,000 ft (900 m) maximum thickness near the basin depositional center (Figure 6-1), thinning out to several hundred meters or less on the basin margins where the salt is absent. The aggregate thickness of the salt in the Salina formation can exceed 2,000 ft (600 m) in the thickest sequences in the depositional center of the basin, thinning out to zero at the basin margins. The salt strata are highly continuous over the basin, and most of the major salt units can be traced for hundreds of kilometers.

In the Goderich area, the aggregate thickness of the Salina formation is about 1,000 ft (300 m), of which approximately 40% consists of salt beds, with the B unit salt being the dominant salt bed.

The geological interpretation assumes that the A-2 evaporite salt bed is continuous and potentially thickens to the west towards the center of the Michigan basin. The regional stratigraphic sequence is well understood from many wells drilled across the basin and locally in the Goderich area. The salt strata are highly continuous over the basin, and most of the major salt units can be traced for hundreds of kilometers.

On a local scale, the continuity of the salt beds can be impacted by the presence of pinnacle reefs, displacement by faults, or the local leaching of salt. The Company can use various tools to characterize geological conditions in nearby areas to assess the possibility of encountering these local ground conditions at the mine.

6.2Mineral Deposit Type

The Goderich Salt Mine is situated in the A-2 salt bed. The A-2 salt is immediately overlain by the A-2 carbonate sequence and underlain by the A-1 carbonate sequence. The base of the A-2 salt bed is located approximately 1,750 ft to 1,760 ft below surface at the mine shafts’ location. Figure 6-2 shows the stratigraphic column at the mine.

The A-2 salt bed in the shaft area is approximately 79 ft thick. Other salt beds above the mine consist of B, D, and F salt beds at progressively shallower depths. The upper most F salt bed is about 980 ft below surface at the shafts’ locations. The salt beds are nearly horizontal and dip at approximately 1.5° to the southwest.

The A-2 salt contains parting features that may be encountered during mining or present stability challenges when shallow in the roof. The clay partings often exhibit rippled surfaces. The features tend to be weak and roof separation is common when located immediately above the roof at room center. The dolomite / anhydrite / clay bands’ (commonly referred to as rock bands) thickness ranges from thin lamina (less than one quarter inch) and four to six inches. The frequency and thickness of


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

the rock bands increase near the top and the bottom of the A-2 salt. Slumping or folding structures within the salt are common.

The rock of the A-2 carbonate bed, which overlies the A-2 salt, is a dolomite. The thickness of the A-2 carbonate bed is about 140 ft and the bedding has prominent partings that range in spacing from less than one inch and one to two feet (Table 6-1). The estimated cohesive strength at bedding features is very low. There is little evidence of cross fracturing or jointing within the dolomite. The rock is prone to raveling as observed in areas where it has been exposed in the mine roof.


Hole ID	From (ft)	To (ft)	Lithology	Thickness (ft)
DDH02	1,676.0	1,754.7	A2_Salt	78.7
DDH03	1,715.7	1,748.0	A2_Salt	32.3
DDH05*	-	-	-	-
DDH06	1,692.3	1,767.2	A2_Salt	74.9
DDH09	1,681.7	1,768.7	A2_Salt	87.0
DDH10	1,696.9	1,781.8	A2_Salt	84.9
DDH11	1,699.0	1,780.0	A2_Salt	81.0
DDH12	1,711.6	1,797.3	A2_Salt	85.7
DDH13	1,673.0	1,759.0	A2_Salt	86.0
DDH14	1,782.7	1,863.5	A2_Salt	80.8
		A2	Average†	82.4

Table 6-1: Thickness of A-2 Salt in Exploration Drilling

Notes: *A2 salt not intercepted in Salina formation.

† Average excludes anomalous boreholes DDH03 andDDH05

Source: SRK from Compass data


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

6.3Stratigraphic Section

Source: Johnson and Gonzales, 1978 as referenced in Dusseault, 2004

Figure 6-1: General Cross-Section of the Michigan Basin


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Source: modified from left: Johnson and Gonzales, 1978 as referenced in Dusseault, 2004 and right: Sanford, 1969

Figure 6-2: Stratigraphic Sequence of the Michigan Basin and the Goderich Salt Mine


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

7Exploration

Exploration on the Goderich Salt Mine is very limited. In the late 1950s, the Sifto Salt Company Ltd. drilled 16 vertical core boreholes, 10 of which were drilled to a depth sufficient to intercept the A-2 salt bed (Figure 7-1). The drilling results are summarized by Kenneth K. Landes (1957) in a report titled Report on Rock Salt Reserves at Goderich, Ontario dated March 30, 1957.

All of the surface exploratory holes were drilled in the 1950’s. Most of the Goderich Mine is located under Lake Huron. This makes any surface exploratory drilling expensive and inherently risky.

Compass has undertaken an in-mine exploration program along with Ground Penetrating Radar (GPR) and in-seam seismic surveys. All the current exploration projects are to verify thickness of the ore deposit and not to determine quality. This is due to the fact the salt has been found to be uniform in its quality.

7.1Procedures – Exploration Other than Drilling

In-seam seismic surveys were conducted at two areas with ground condition problems at the current southern extent of the mine workings (Figure 7-1). In-seam seismic is able to detect disturbances in salt continuity but cannot observe salt thickness. The survey conducted by Associated Mining Consultants (AMC) in 1997 concluded that they had encountered “events” coinciding with “the range at which hard material had been encountered during drilling”. Mining operation efforts were halted at the first seismic reflector.

The in-seam seismic survey done in 2013 by DMT showed P – and S- waves within salt with some detected seismic reflections showing disturbances in the salt interpreted as possible faults or increases in organic material.

In 2019, the mine began using GPR to identify the thickness of the A-2 Salt layer in development. The mine purchased a Sensors and Software Pulse EKKO 100 MHz antenna, and processing software suite. The thickness was calculated using common midpoint (CMP) survey-derived wave speeds, taking the geometry of the GPR system into account and propagating the associated uncertainties. The surveys have identified areas of decreased and increased thickness in the mine allowing the mine plan to be adjusted accordingly.

7.2Exploration Drilling

The report by Landes concluded that commercial salt beds have been defined in the A-2 and F salt beds. The A-2 salt was reported as having a minimum mining thickness of 70 ft with an average NaCl content of 98.17%. The F salt was reported at a minimum mining thickness of 15 ft with an average NaCl content of 98.24%. The other salt units, A-1, B, and D were deemed at the time as either too thin or with too many impurities for commercial extraction.

The average thickness of the A-2 salt bed is 82.4 ft, as defined by eight drill intercepts that have pierced through the whole unit Table 6-1. Drill intercepts closest to the lease (boreholes 9, 10, 11 and 12) average 84 feet thickness and the salt zone generally thickens moving to the west, where mining is occurring. Interestingly, the A-2 salt thins to a thickness of 32 ft on borehole 3 and completely disappears in borehole 5. Landes (1957) interprets the disappearance of the A2 salt in borehole 5 as being due to leaching of the salt and subsequent collapse of the overlying beds, as evidenced by a steepening of the beds and the presence of salt-filled fractures in the core. Landes


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

does not however attribute the thinning of the A-2 salt in borehole 3 to the same leaching process as no brecciation was observed and the A-2 carbonate is also thinned by over 70 ft. Therefore, to explain the anomalous situation at borehole 3 by leaching would involve not only dissolving the upper three-fifth of the A-2 salt but also half of the overlying A-2 dolomite, all without disturbing the strata above. As such, Landes interpreted this oddity as being related to faulting though no faults were interpreted in the log and the QP is not aware of any mapped fault in the area. The orientation of such a fault is unknown but restricted by the fact that it has not been observed in existing workings. However, Terry Carter, consultant geologist for Compass with many years of experience at the mine, believes that the thinning of A-2 salt on borehole 3 could still be due to salt dissolution. Further geological work is required to understand the reason for salt thinning in this area.

Source: Compass Minerals

Figure 7-1: Exploration Drilling and In-seam Seismic Surveys at the Goderich Salt Mine (existing mine workings in red)


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

7.3Procedures – Drilling Exploration

The first exploration holes were drilled in the 1950’s. Drilling logs exist; however, drilling procedures have not been found.

In 2019, Compass Minerals began an inseam drilling program. This program was designed to confirm the thickness of the ore body in the proposed new mine workings and was not designed to collect information about quality of the salt.

The drilling program used a small diamond drill rig along with directional drilling tool. The drillholes were located to drill into areas where new mine workings are proposed. The typical drillhole was drilled using NQ core barrel. The drill holes were drilled horizontally with 20 ft cemented casings. The cement was allowed to cure for 12 hours, then pressure tested to 1,000 psi for 10 minutes. If the casing fails the pressure test, re-cementing the casing is performed. If the casing fails the pressure test twice, the hole is abandoned, and another location is drilled.

Every 100 meters, upwards and then downwards wedges were branched off the main horizontal hole to intersect with the anhydrite formations above and below the salt. All drill holes are logged, and cores remain within Goderich Mine to be used for future reference.

The drilling program is an on-going program with new sites chosen as mine planning dictates.

7.4Characterization of Hydrology

Golder Associates (2013) summarized hydrogeological conditions and observations made during the sinking of the three shafts. The sequence of geologic strata typically encountered near the shafts are summarized in Table 7-1.

Table 7-1: Typical Borehole Log Near Shafts at Goderich Mine

This geologic sequence is consistent with the information available from shaft sinking logs. The shale beds and salt beds of the Salina Formation in the area represent an aquitard and form the base of the more active groundwater flow system present in the overlying units (starting at 230 m, or about 750 ft bgs). It is understood that groundwater in the Lucas, Amherstburg, Bois Blanc, and Bass Islands Formations is typically fresh to brackish, with water in the deeper Salina units being of high salinity. An additional source of information includes geologic observations that were made during shaft sinking and summarized in a report by Phillips (2000). The observations are summarized in Table 7-2. Below the superficial sand and gravel deposits associated with the lake bed and riverbed,


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

the strata are nearly horizontally bedded. This means that strata can be correlated as approximately horizontal between the nearby boreholes and shafts.

Table 7-2: Geologic Conditions Identified During Shaft Sinking

As part of the study by Golder Associates (2013), a hydrogeological investigation was conducted in test well VWP-1 to provide information and aid in the design of a program for re-lining shafts #1 and #2. This investigation included collecting geophysical data, borehole video images, and geological logging. Hydrogeologic testing included flow profiling, hydraulic testing, and water chemistry sampling. The test borehole was cemented and abandoned upon completion of test program. The measured water levels and flow conditions from the test program are summarized on Table 7-2, along with estimates of hydraulic conductivity for the various intervals.

Table 7-3: Hydrogeologic data from Test Well VWP-1

Appendix B shows a log of the inflows encountered during the sinking of shafts #1 and #2. This data is considered relevant to the prediction of hydrogeological inflow conditions to the underground workings and around the shaft seals.

The review of hydrogeologic data is summarized in the following points:

• The dolostone (shaley dolomite) of the Lucas, Amherstburg, Bois Blank, and Bass Island Formations to a depth of about 230 m are water bearing with artesian flow measured through the sequence.

• There is presence of vertical groundwater gradients to the depth of about 230 m with hydraulic heads varied from 1 to 3 m above ground between depths of 40 to 89 m. Average hydraulic head


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

of 4.3 m above ground between depths of 90 and 230 m, resulting in strong artesian flow in boreholes.

• Significant artesian flow rates of 18 to 32 L/sec (285 to 507 gpm) were measured throughout the Amherstburg, Bois Blanc, and Bass Island Formation between depths of 97 and 217 m with the deepest major flow zone encountered at a depth of 213 m. Significant flow producing zones were encountered through the upper 200 m of rock generally corresponding to karstified, weathered bedding partings, vertical fractures, and stratigraphic discontinuities.

• The anhydrite beds identified at depths between approximately 230 and 248 m in the base of the Bass Island Formation, when intact as they were observed in Test Well VWP-1, likely represent an aquitard or caprock to the large-scale groundwater circulation.

• The Salina Formation G and F Members encountered in Test Well VWP-1 between depths of 248 and 258 m appeared to be intact and did not exhibit an indication of significant weathering. However, some minor open bedding partings were observed that may be associated with minor groundwater flow zones.

• Groundwater level measured in the Salina Formation was approximately 120 m below ground surface. The strong hydraulic head difference of 124 m observed across the lower Bass Island Formation anhydrite beds suggests that they are acting as an effective aquitard, at least in the immediate vicinity of Test Well VWP-1.

• The observed intact rock and absence of major flow zones below 213 m in Test Well VPW-1 are generally consistent with observations from the original sinking of Shaft #2, which reports dry conditions below 219 m. However, regular groundwater inflows to the depth to 335 m with a flow range of 0.5 to 1.5 L/sec were reported during construction of Shaft #1.

7.5Exploration – Geotechnical Data

No geotechnical data was found for the above ground exploration holes. The current drilling program does not contain any provisions for the collection or testing for geotechnical purposes.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

Source: Compass Minerals

Figure 7-4: Drill Hole Locations

7.6Description of Relevant Exploration Data

The combination of historic data collected through historical exploration, the large body of geologic knowledge of the area and the Michigan Basin, combined with the long operational history of the mine and Compass Minerals’ underground GPR and drilling exploration has created a strong understanding of the thickness and continuity of the salt bed. Furthermore, the salt deposit has been shown to be almost pure sodium chloride (~98%), less some anhydritic interbedding. The presence of the anhydritic banding is common in salt beds and is due to the depositional process of halite. The undulating thickness as discovered using GPR is localized and has no significant impact on reserves.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

The mine has been in operation for over 60 years and has accumulated a wealth of knowledge about the homogeneity and continuity of the salt bed. As mining operations continue to the west, towards the center of the basin, all geologic information points to the salt bed becoming thicker. The only limiting factor of the mine and the reserves, is the boundaries of the lease.


Compass Minerals International, Inc. Goderich Mine 2021 Technical Report Summary

8Sample Preparation, Analyses and Security

All of the surface exploration occurred during the 1950’s. The previously referenced report by Landes concluded the A-2 salt had an average NaCl content of 98.17%. The report does not indicate the tests performed, if the samples were composited or any specific detail of how analytical testing and sample handling were performed. However, the purities described in the Landes report are indicative of the purity levels found within the mine.

Halite is a sedimentary rock that is formed when large volumes of sea or salty water is evaporated from an arid climate basin. The basin has a replenishing flow of salty water and a restricted input of fresh or any other water. This depositional environment creates large uniform beds of halite. The size and uniformity of halite beds allows the mining environment where exploratory sampling can be limited in scope. Compass Minerals samples for purity during production, as described in Section 10.

8.1Sample Preparation and Quality Control