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North Yorkshire Polyhalite Project

Client
Service Performed
Dr. Sauer & Partners provided commercial support, SCL design verification and functioned as a mediator between Sirius Minerals’ mining and construction team.
Commencement - Services
April 01, 2019
Completion - Services
October 31, 2019
Location
Whitby
Yorkshire
YO11 3ZB
United Kingdom
Geology description

Most of the MTS is developed within the Redcar Mudstone Formation. It comprises alternating layers of silty mudstone and clayey siltstones with subordinated thin beds of limestone and sandstone.

Bands of ironstone nodules and fossil shells as well as pyrite are present in places. Multiple major fault systems were identified that cut the MTS alignment. 

Geology types
Description

North Yorkshire holds one of the largest, high grade polyhalite reserves worldwide. It is located within the North York Moors National Park, ca. 1800m below surface. Once processed, this mineral functions as an organic fertilizer to boost harvest. Sirius Minerals plc are currently developing the infrastructure to mine the polyhalite. This operation requires deep shafts to access the mineral body but also demands an extensive mass transport system (MTS) to keep the impact on the National Park to a minimum. Therefore, at ca. 350m below surface, a series of SCL tunnels link the deep shafts to a conveyor belt system, which again connects the mining operation via a 37km TBM tunnel to its material handling facility.

Activity
Categories
Construction methods
Tunnel length
37km
Project overview
Woodsmith mine site close to Whitby
Project number
515C
Final cost
£4.2 billion GBP

Leesburg Inter-Quarry Tunnel - Execution

Service Performed
Site supervision on behalf of Luck Stone Corporation including supervision of all SEM activities, quality assurance services, cost and schedule control and design coordination on site.
Commencement - Services
April 01, 2018
Completion - Services
March 01, 2019
Location
Leesburg Plant
20210 Luck Lane
Ashburn, Virginia, VA 20147
United States
Geology description

Located within the Culpeper Basin, a sedimentary rock formation characterized to be of Lower Mesozoic Age. The existing Luck Stone quarry is situated in a Diabase intrusion (dyke) of this sedimentary rock.

Geology types
Description

Luck Stone Corporation (LSC) is the nation's largest family owned and operated producer of crushed stone, sand and gravel. At their plant in Leesburg, Virginia, Luck Stone Corporation acquired a new quarry, which is located to the West of Goose Creek river. An inter-quarry tunnel was constructed to link the existing South-Eastern pit with the new West pit. The tunnel's cross section is approximately 45 feet in diameter, and the tunnel's length is approximately 1275 feet. The tunnel crosses the Goose Creek river approximately 50 feet beneath. The excavation method was drill and blast in hard rock (diabase).

Activity
Categories
Special Construction techniques
Tunneling under
Tunnel length
1275 feet
South-East portal - final stage
South-East portal - construction stage
Project number
242E
Final cost
$13 million USD

Leesburg Inter-Quarry Tunnel - Design

Service Performed
Conceptual design with various tunnel options. Final tunnel design consisting of drawings, specifications, and calculations. Client support during bid phase.
Commencement - Services
January 01, 2017
Completion - Services
April 01, 2018
Location
Leesburg Plant
20210 Luck Lane
Ashburn, Virginia, VA 20147
United States
Geology description

Located within the Culpeper Basin, a sedimentary rock formation characterized to be of Lower Mesozoic Age. The existing Luck Stone quarry is situated in a Diabase intrusion (dyke) of this sedimentary rock.

Geology types
Description

Luck Stone Corporation (LSC) planned to open a new quarry on the Western side of Goose Creek river, a component of the Virginia Scenic Rivers System. A tunnel was envisioned to connect the new Western quarry with the existing South-Eastern one below the river. The rock cover between the tunnel and the river was approximately 50 feet. The tunnel is 1275 feet long with a diameter of 45 feet. It is designed to accommodate large scale mining trucks as well as a conveyor belt for material transport which is scheduled to be installed in the future.

Activity
Categories
Construction methods
Special Construction techniques
Tunneling under
South-East portal excavation sequence
South-East portal excavation
Vertical bench drilling
Project number
242D
Final cost
$13 million USD

Luck Stone Fairfax Plant – Inspection Works

Service Performed
In-depth inspection of a connector tunnel in accordance with TOMIE manual and the SNTI manual of the U.S. Department of Transportation - FHWA.
Commencement - Services
July 01, 2016
Completion - Services
July 31, 2016
Location
15717 Lee Hwy
Centreville, VA, VA 20121
United States
Geology description

The prevalent rock type of the tunnel is diabase. The rock mass is moderately jointed, with closely to very closely spaced joints. The rock is slightly weathered.

Geology types
Description

Inspected tunnel connects two quarries at the Luck Stone Corporation Fairfax plant. The tunnel crosses beneath the Lee Highway (US Route 29), in a North-South direction. Built ca. 1975, the tunnel is partially unlined and in rock; approx. 190 feet long and approx. 22 feet wide and 22 feet high. As the Northern quarry side is already exhausted, the tunnel is rarely used with just one or two transits per day.
Dr. Sauer & Partners performed an in-depth inspection of a connector tunnel; assessed the tunnel condition and provided remedial measures.

Activity
Service areas
Construction methods
Tunneling under
Connector Tunnel - North Portal / Highwall
Connector Tunnel - South Portal / Highwall
Project number
242E1
Final cost
n/a

Cigar Lake Operation

Owner
Service Performed
Site supervision services, consulting, monitoring and on-site design performed by senior engineer and two tunnel inspectors.
Commencement - Services
September 01, 2012
Completion - Services
August 01, 2015
Location
2121, 11th St W
Saskatoon, SK S7M 1J3
Canada
Geology description

Highly thermo hydraulically weathered metapelites in form of weak rock and clayey-silty-sandy soils, highly anisotropic, cut with slickensided graphitic planes.

Geology types
Description

Cameco Cigar Lake is the world's highest grade uranium deposit. It is considered one of the world's most technically challenging uranium deposits to mine. The ore body and the ground around has to be bulk frozen prior to extraction of the ore using high pressure water jets. Development of the freeze/production cross-cuts take place beneath the ore body in unstable, soil-like highly weathered and anisotropic rock. A flexible shotcrete lining with longitudinal slots of special yielding elements together with systematic rock bolting were utilized to cope with squeezing ground conditions.

Categories
Mine
Final cost
$50,000,000
Construction methods
Special Construction techniques
Pocket excavation in unstable ground conditions
Installed yielding elements prior to spraying shotcrete
Project number
455E
Project Type
Final cost
$50 million CAD
Completion date
Ongoing