An environmental study for a proposed new Larson Quarry Expansion is now available for review.

Washington County ordered preparation of an Environmental Assessment Worksheet (EAW) to assess the potential for environmental impacts of the proposed project. Holcim-MWR, Inc. proposes to expand their existing limestone quarry, known as the Larson Quarry (in Grey Cloud Island Township), to the east onto an adjacent 148-acre property. No change in quarry operations or production levels are proposed.

The EAW comment period, which is prescribed by state law, begins on Dec. 3 and will end on Jan. 17, 2025. Copies of the EAW are available for review through the Washington County website at WashingtonCountyMN.gov/LarsonQuarryEAW with a hard copy available for review at the Park Grove Library, 7900 Hemingway Ave. S., Cottage Grove, MN 55016.

Written comments received by Washington County during the comment period will be considered by the Planning Advisory Commission and County Board in making their decision as to the need for further environmental study. For further information, contact Daniel Elder at Washington County, PublicWorks@co.washington.mn.us.

The Larson Quarry and expansion area is in Grey Cloud Island Township, Washington County, Minnesota. No change in quarry operations or production levels is proposed. The expansion will extend the life of the mine by 20-25 years

In the EAW, the project is described as:

“Holcim-MWR, Inc. (Holcim) currently operates a limestone quarry, known as the Larson Quarry, located in Grey Cloud Island Township, Washington County, Minnesota. Holcim (formerly Aggregate Industries) proposes to expand the existing quarry (Project) onto a 148-acre property (Site or Project Area) located east of County Road (CR) 75, the majority of which they have owned since 1972. The Project will involve either the relocation of CR 75 around the eastern perimeter of the proposed quarry limits (Option 1) or the construction of a bridge on CR 75 with an underpass below CR 75 (Option 2) to access the eastern limestone reserves. The expansion will increase the quarry area by approximately 53 to 70 acres depending upon the option ultimately permitted.

Project Background

The existing quarry was initially established in 1957 and has been in operation for over six decades. The quarry mines limestone and produces high quality construction aggregates, serving the twin cities metropolitan area. Existing quarry operations include clearing and grubbing, removal of topsoil and overburden, dewatering, drilling, and blasting, extraction, processing (crushing, screening, and washing), stockpiling, and loading operations. Equipment utilized in the mining operation includes a rock drill, front-end loaders, a hydraulic shovel, a mobile track-mounted primary crusher and feeder, and an overland conveying system to the main processing plant, which is in the southern portion of the existing Larson Quarry. The mining season typically extends from late March through November each year. No changes to the existing hours of operation, staffing, mining, or processing activities are proposed.

Operations Overview

The limestone is currently being quarried in two separate cuts or benches within the active mining area. The upper bench, about 50 feet thick, is typically removed first followed by extraction of the lower bench, also about 50 feet. Once material is blasted and extracted, it is transported via a conveyer system to the processing plant where it is crushed, screened and/or washed. Processed materials are loaded onto barges or trucks for transportation to their destination. The majority of the processed material is currently and will continue to be transported via barge up the Mississippi River to the company's distribution yard in St. Paul. Some material will also be trucked out on CR 75, depending upon the demand of local projects.

The location of this deposit along the Mississippi River, in conjunction with Holcim’s existing barge fleet at the Larson Quarry allows for the end product to be delivered into the heart of the Twin Cities for commercial and residential uses in a more efficient manner than if all of the material was transported by truck. This results in reduced truck traffic and CO2 emissions. Existing transportation modes are anticipated to continue throughout the life of the expansion area.

Mining Methods

The expansion area will be mined utilizing the same methods used at the existing Larson Quarry. The quarry is dewatered, which lowers the groundwater table within the limestone deposit to allow removal of the limestone using dry mining methods. Trees are removed in phases as areas are prepared for mining. Topsoil and overburden are removed and used to create screening berms and safety berms. The berms are seeded and mulched, and vegetation is established to reduce the potential for erosion. The material used to construct the screening berms may eventually be used in reclamation activities.

Following the removal of topsoil and overburden, the underlying bedrock is drilled and blasted to break up the rock into small pieces that can be transported by conveyor to the processing plant located in the southern portion of the existing Larson Quarry. Blasting is conducted by a third-party explosives contractor who is responsible for the engineering design of each blast. Each blast consists of a number of holes spaced and drilled to exact specifications according to the blast design. Each blast is designed to minimize ground vibration and sound pressure level while still providing sufficient energy to fracture the bedrock for extraction.

Seismographs are placed between the blasting area and the closest structures to record ground vibration and sound pressure levels from each blast to verify that safe limits established by the US Bureau of Mines are not exceeded as well as to provide data for the blast contractor to use in the analysis and design of subsequent blasts.

Blasting at the quarry has been occurring at the Site since the 1950’s and occurs as needed based upon production needs. All blasting occurs during normal business hours, Monday through Friday. The plant manager maintains a text list to notify neighbors of the blast schedule and provide a 5 minute warning before blasting occurs

The quarry operates seasonally, typically from late March through November each year. The main processing plant is located approximately three quarters of a mile to the southwest of the expansion area and operates in conformance with the hours permitted by Grey Cloud Island Township. The approved operating hours for the 2023 and 2024 mining seasons were from 6:00 a.m. to 10:00 p.m., Monday through Friday and 7:00 a.m. to 12:00 p.m. on Saturdays.

Expansion Area

The majority of the expansion area has been held in reserve since 1972 and has been part of the long-range planning of the quarry since at least 1971. The expansion area has been identified as a future mine expansion on local land use plans for the last several decades. An environmental review was completed for the expansion area in 2005 with Washington County as the RGU. The 2005 Environmental Review included the northern portion of the existing Larson Quarry located west of CR 75 as well as the eastern portion of the Larson Quarry located west of CR 75. Washington County adopted a Findings of Fact and a Negative Declaration on the need for an Environmental Impact Statement for the proposed expansion on September 20, 2005.

CR 75 runs north-south between the existing quarry and the proposed expansion area, creating a physical barrier between the properties. In order to access the eastern limestone reserves and provide for material transport between the expansion area and the existing processing facility, Holcim is considering two options to access the eastern reserves: 1) Realignment of CR 75 and 2) Bridge on CR 75 with underpass through CR 75 right of way on quarry floor. Both options are described in detail in the paragraphs below and are further analyzed in this EAW.

Option 1 involves relocation of CR 75 to the east around the proposed quarry expansion limits. This option allows the natural progression of the quarry to proceed uninterrupted to the east. The current quarry limits are set back 200 feet west of the CR 75 right-of-way. Under this option, the Proposer will relocate CR 75 and establish a new right-of-way, the current right-of-way will be vacated and quarry activity will continue from the current mine limits through the vacated right-of-way in a west to east progression.

CR 75 is a rural two-lane roadway with no turning lanes, sidewalks, or trails. Based on Minnesota Department of Transportation (MnDOT) 2018 traffic count data, the segment of CR 75 proposed for relocation has an annual average daily traffic (AADT) volume of 1,550 with a posted speed of 40 mph. The current right-of-way width is 66 feet. The existing roadway functional classification of CR 75 is identified in the Washington County 2040 Transportation Plan1 (2040 Transportation Plan) as a major collector, serving shorter trips and distributing traffic from neighborhoods, commercial and industrial areas to the arterial system. CR 75 from 105th Street S. to 14th Avenue (which includes the segment proposed for relocation) is identified as a candidate for jurisdictional change from a county road to a local township road in the 2040 Transportation Plan.

The proposed realignment maintains the 66-foot right-of-way rural undivided roadway with 12-foot lanes and 4-foot shoulders as illustrated on the typical section below. The new road realignment will be constructed within the 500-foot mining setback from Grey Cloud Channel. CR 75 relocation will require 9-16 acres of clearing and grubbing, the construction of approximately 6,000 linear feet of new roadbed replacing approximately 2,500 linear feet of existing CR 75 roadbed, and the relocation of utilities located along the current right-of-way.

Much of the construction of the new alignment can be accomplished without disrupting typical CR 75 traffic patterns. Construction to connect the north and south end sections of the newly aligned road could take several days up to several weeks.

Option 1 allows for the location of the existing Larson Quarry site access to be maintained. Extraction and transfer of material from the active quarry face to the processing area would occur at recessed elevations below the surrounding grade. The eastern reserves would be accessed by progressive quarry activity from the existing eastern quarry limits moving to the east.

Since road realignment represents a relatively small section of road and does not include any new connections, the average daily traffic volume is not expected to change current traffic patterns or volumes. Washington County has jurisdiction for CR 75, therefore, any plans to modify the road would require coordination with and approval from the County. It is anticipated that a Memorandum of Understanding or Developer’s Agreement would be executed that would address approved engineering design and construction plans, establish the method for financing (Proposer will be financially responsible for the realignment), as well as the establishment of maintenance responsibilities of the realigned roadway.

Option 1, CR 75 Realignment has been part of the long-range quarry plan since at least 1971, when a 50-year planning study was prepared (1971 Plan) that provided a blueprint for quarry development within the Grey Cloud Island Township community.2 The longstanding plan of relocating CR 75 is indicated as Stage Two on Inset 6-1 of the Operations Plan from the 1971 Plan shown below.

Option 2 Bridge Option

Option 2 is to construct a bridge on CR 75 with an underpass below CR 75 that provides an east-west connection at the existing quarry floor elevation beneath the CR 75 roadway and access to the eastern quarry reserves. This option will allow equipment and material to be transported by trucks or conveyor between the existing quarry and the expansion area along the quarry floor. Under Option 2, mining will be continuous from one quarry area to the other without having to start the eastern operations “at grade.” Option 2 will not require a new site access off CR 75 or an at grade truck or conveyor crossing at CR 75 between the processing area and the expansion area. Truck traffic or conveying equipment between these areas will be below CR 75 through the underpass.

The bridge will be located near the middle of the western mining limits of the expansion area. Construction of the bridge will involve a temporary relocation of County Road 75 and utilities around the eastern portion of the construction area. The existing roadway will be removed within the construction area. Limestone will be removed through a corridor running from the existing eastern limits through the 200-foot setback area west of CR 75, through the CR 75 R-O-W and through the 200-foot setback area on the east side of CR 75. The corridor will be approximately 100 feet wide benching down to the floor of the quarry and creating a fifty-foot wide underpass at the floor of the quarry that can accommodate vehicles, mine equipment between the two quarry areas, and the transfer of limestone from the expansion area to the processing area located in the existing quarry. Once the limestone has been removed through the corridor, additional limestone mining will be required to open a staging area for mining the eastern reserves and provide sufficient room for bridge construction. The bridge will be constructed, the current road realignment and utilities restored, and the temporary road removed. The construction of the bridge will require a temporary detour for an estimated three to five years to allow time to create the underpass, staging area, and build the bridge.

Reclamation

Reclamation of the Larson Quarry will be performed upon conclusion of mining activity. The intent of reclamation is to leave the site in a stable condition, minimize the potential for erosion, and establish site conditions that allow for future development of the land. Plan Sheets C3.1 and C3.2 illustrate the reclamation condition of the existing quarry and expansion area and include information on the approximate site elevations upon completion of reclamation grading. The Reclamation Plan is subject to the ongoing regulatory authority of Grey Cloud Island Township and Washington County and the standards contained within their land use ordinances and is subject to a reclamation bond. Reclamation involves final grading, slope stabilization, and seeding and mulching to establish vegetation in upland areas of the site. Option 1 will leave the site edge matched with the current approved reclamation plan of the existing Larson Quarry and will include a quarry lake with a shallow bay wetland area near the south end of the existing quarry, a deeper lake on the northern end of the existing quarry, and a deeper bay in the eastern expansion area. A gentle entry lake access area will allow for future development of a beach and boat access on the eastern portion of the Site. The lakeshore will include safe water exits along the shoreline. Option 2 Reclamation creates the same shallow bay and deeper lake areas as described above, but the eastern bay will be separated from the main lake by the CR 75 corridor and setback areas with a channel under the bridge that connects the eastern bay with the main lake.

Most of the lake perimeter will be bordered by near vertical limestone bluffs extending from the existing grade at approximately 740 feet above mean sea level (msl) down to the lake level of approximately 690 msl consistent with the existing approved quarry reclamation plan. The bluffs will be like those present along the Mississippi River on the western boundary of the existing Larson Quarry property. The water level in the lake will be established once the dewatering ceases and water levels return to pre-project conditions. The entire quarry expansion area that is quarried will become a lake once dewatering operations have ceased and will not require reclamation grading or establishment of vegetation.

Reclamation for both options will leave the setback areas outside of the quarry limits available for open space and/or future rural residential development along the northern and eastern perimeter of the quarry in accordance with zoning and standards in effect at that time. Final development of the property is outside of the scope of this EAW. When a development proposal is ultimately brought forward, it will be required to meet the ordinances in effect at that time and must go through the permitting processes in place at that time.

Life of the Project

The existing Larson Quarry has provided construction aggregate material essential for private and public infrastructure and development projects since the 1950’s. There are only five to seven years of life remaining in the existing permitted quarry area and the Project is expected to extend the life of the quarry by an additional 20-25 years.”

Mining Methods

The expansion area will be mined utilizing the same methods used at the existing Larson Quarry. The quarry is dewatered, which lowers the groundwater table within the limestone deposit to allow removal of the limestone using dry mining methods. Trees are removed in phases as areas are prepared for mining. Topsoil and overburden are removed and used to create screening berms and safety berms. The berms are seeded and mulched, and vegetation is established to reduce the potential for erosion. The material used to construct the screening berms may eventually be used in reclamation activities.

Following the removal of topsoil and overburden, the underlying bedrock is drilled and blasted to break up the rock into small pieces that can be transported by conveyor to the processing plant located in the southern portion of the existing Larson Quarry. Blasting is conducted by a third-party explosives contractor who is responsible for the engineering design of each blast. Each blast consists of a number of holes spaced and drilled to exact specifications according to the blast design. Each blast is designed to minimize ground vibration and sound pressure level while still providing sufficient energy to fracture the bedrock for extraction.

Seismographs are placed between the blasting area and the closest structures to record ground vibration and sound pressure levels from each blast to verify that safe limits established by the US Bureau of Mines are not exceeded as well as to provide data for the blast contractor to use in the analysis and design of subsequent blasts.

Blasting at the quarry has been occurring at the Site since the 1950’s and occurs as needed based upon production needs. All blasting occurs during normal business hours, Monday through Friday. The plant manager maintains a text list to notify neighbors of the blast schedule and provide a 5 minute warning before blasting occurs

The quarry operates seasonally, typically from late March through November each year. The main processing plant is located approximately three quarters of a mile to the southwest of the expansion area and operates in conformance with the hours permitted by Grey Cloud Island Township. The approved operating hours for the 2023 and 2024 mining seasons were from 6:00 a.m. to 10:00 p.m., Monday through Friday and 7:00 a.m. to 12:00 p.m. on Saturdays.

Expansion Area

The majority of the expansion area has been held in reserve since 1972 and has been part of the long-range planning of the quarry since at least 1971. The expansion area has been identified as a future mine expansion on local land use plans for the last several decades. An environmental review was completed for the expansion area in 2005 with Washington County as the RGU. The 2005 Environmental Review included the northern portion of the existing Larson Quarry located west of CR 75 as well as the eastern portion of the Larson Quarry located west of CR 75. Washington County adopted a Findings of Fact and a Negative Declaration on the need for an Environmental Impact Statement for the proposed expansion on September 20, 2005.

CR 75 runs north-south between the existing quarry and the proposed expansion area, creating a physical barrier between the properties. In order to access the eastern limestone reserves and provide for material transport between the expansion area and the existing processing facility, Holcim is considering two options to access the eastern reserves: 1) Realignment of CR 75 and 2) Bridge on CR 75 with underpass through CR 75 right of way on quarry floor. Both options are described in detail in the paragraphs below and are further analyzed in this EAW.

Option 1 involves relocation of CR 75 to the east around the proposed quarry expansion limits. This option allows the natural progression of the quarry to proceed uninterrupted to the east. The current quarry limits are set back 200 feet west of the CR 75 right-of-way. Under this option, the Proposer will relocate CR 75 and establish a new right-of-way, the current right-of-way will be vacated and quarry activity will continue from the current mine limits through the vacated right-of-way in a west to east progression.

CR 75 is a rural two-lane roadway with no turning lanes, sidewalks, or trails. Based on Minnesota Department of Transportation (MnDOT) 2018 traffic count data, the segment of CR 75 proposed for relocation has an annual average daily traffic (AADT) volume of 1,550 with a posted speed of 40 mph. The current right-of-way width is 66 feet. The existing roadway functional classification of CR 75 is identified in the Washington County 2040 Transportation Plan1 (2040 Transportation Plan) as a major collector, serving shorter trips and distributing traffic from neighborhoods, commercial and industrial areas to the arterial system. CR 75 from 105th Street S. to 14th Avenue (which includes the segment proposed for relocation) is identified as a candidate for jurisdictional change from a county road to a local township road in the 2040 Transportation Plan.

The proposed realignment maintains the 66-foot right-of-way rural undivided roadway with 12-foot lanes and 4-foot shoulders as illustrated on the typical section below. The new road realignment will be constructed within the 500-foot mining setback from Grey Cloud Channel. CR 75 relocation will require 9-16 acres of clearing and grubbing, the construction of approximately 6,000 linear feet of new roadbed replacing approximately 2,500 linear feet of existing CR 75 roadbed, and the relocation of utilities located along the current right-of-way.

Much of the construction of the new alignment can be accomplished without disrupting typical CR 75 traffic patterns. Construction to connect the north and south end sections of the newly aligned road could take several days up to several weeks.

Option 1 allows for the location of the existing Larson Quarry site access to be maintained. Extraction and transfer of material from the active quarry face to the processing area would occur at recessed elevations below the surrounding grade. The eastern reserves would be accessed by progressive quarry activity from the existing eastern quarry limits moving to the east.

Since road realignment represents a relatively small section of road and does not include any new connections, the average daily traffic volume is not expected to change current traffic patterns or volumes. Washington County has jurisdiction for CR 75, therefore, any plans to modify the road would require coordination with and approval from the County. It is anticipated that a Memorandum of Understanding or Developer’s Agreement would be executed that would address approved engineering design and construction plans, establish the method for financing (Proposer will be financially responsible for the realignment), as well as the establishment of maintenance responsibilities of the realigned roadway.

Option 1, CR 75 Realignment has been part of the long-range quarry plan since at least 1971, when a 50-year planning study was prepared (1971 Plan) that provided a blueprint for quarry development within the Grey Cloud Island Township community.2 The longstanding plan of relocating CR 75 is indicated as Stage Two on Inset 6-1 of the Operations Plan from the 1971 Plan shown below.

Option 2 Bridge Option

Option 2 is to construct a bridge on CR 75 with an underpass below CR 75 that provides an east-west connection at the existing quarry floor elevation beneath the CR 75 roadway and access to the eastern quarry reserves. This option will allow equipment and material to be transported by trucks or conveyor between the existing quarry and the expansion area along the quarry floor. Under Option 2, mining will be continuous from one quarry area to the other without having to start the eastern operations “at grade.” Option 2 will not require a new site access off CR 75 or an at grade truck or conveyor crossing at CR 75 between the processing area and the expansion area. Truck traffic or conveying equipment between these areas will be below CR 75 through the underpass.

The bridge will be located near the middle of the western mining limits of the expansion area. Construction of the bridge will involve a temporary relocation of County Road 75 and utilities around the eastern portion of the construction area. The existing roadway will be removed within the construction area. Limestone will be removed through a corridor running from the existing eastern limits through the 200-foot setback area west of CR 75, through the CR 75 R-O-W and through the 200-foot setback area on the east side of CR 75. The corridor will be approximately 100 feet wide benching down to the floor of the quarry and creating a fifty-foot wide underpass at the floor of the quarry that can accommodate vehicles, mine equipment between the two quarry areas, and the transfer of limestone from the expansion area to the processing area located in the existing quarry. Once the limestone has been removed through the corridor, additional limestone mining will be required to open a staging area for mining the eastern reserves and provide sufficient room for bridge construction. The bridge will be constructed, the current road realignment and utilities restored, and the temporary road removed. The construction of the bridge will require a temporary detour for an estimated three to five years to allow time to create the underpass, staging area, and build the bridge.

Reclamation

Reclamation of the Larson Quarry will be performed upon conclusion of mining activity. The intent of reclamation is to leave the site in a stable condition, minimize the potential for erosion, and establish site conditions that allow for future development of the land. Plan Sheets C3.1 and C3.2 illustrate the reclamation condition of the existing quarry and expansion area and include information on the approximate site elevations upon completion of reclamation grading. The Reclamation Plan is subject to the ongoing regulatory authority of Grey Cloud Island Township and Washington County and the standards contained within their land use ordinances and is subject to a reclamation bond. Reclamation involves final grading, slope stabilization, and seeding and mulching to establish vegetation in upland areas of the site. Option 1 will leave the site edge matched with the current approved reclamation plan of the existing Larson Quarry and will include a quarry lake with a shallow bay wetland area near the south end of the existing quarry, a deeper lake on the northern end of the existing quarry, and a deeper bay in the eastern expansion area. A gentle entry lake access area will allow for future development of a beach and boat access on the eastern portion of the Site. The lakeshore will include safe water exits along the shoreline. Option 2 Reclamation creates the same shallow bay and deeper lake areas as described above, but the eastern bay will be separated from the main lake by the CR 75 corridor and setback areas with a channel under the bridge that connects the eastern bay with the main lake.

Most of the lake perimeter will be bordered by near vertical limestone bluffs extending from the existing grade at approximately 740 feet above mean sea level (msl) down to the lake level of approximately 690 msl consistent with the existing approved quarry reclamation plan. The bluffs will be like those present along the Mississippi River on the western boundary of the existing Larson Quarry property. The water level in the lake will be established once the dewatering ceases and water levels return to pre-project conditions. The entire quarry expansion area that is quarried will become a lake once dewatering operations have ceased and will not require reclamation grading or establishment of vegetation.

Reclamation for both options will leave the setback areas outside of the quarry limits available for open space and/or future rural residential development along the northern and eastern perimeter of the quarry in accordance with zoning and standards in effect at that time. Final development of the property is outside of the scope of this EAW. When a development proposal is ultimately brought forward, it will be required to meet the ordinances in effect at that time and must go through the permitting processes in place at that time.

Life of the Project

The existing Larson Quarry has provided construction aggregate material essential for private and public infrastructure and development projects since the 1950’s. There are only five to seven years of life remaining in the existing permitted quarry area and the Project is expected to extend the life of the quarry by an additional 20-25 years.”