Changing Use of Mines

Constant changes to mine production operations and an increase in mine fires over the past few years make it more prudent than ever to review potential fire and safety issues.

New production techniques and non-mining operations now being conducted underground-such as mineral processing and scientific laboratories-have created a large gap between the current uses and the existing regulatory code requirements. This article provides a case study of fire and life safety compliance for a laboratory facility, which the owner, operators, designers and authorities all have agreed with.

Although this article deals with a unique facility, the approach and application of the solution achieved a reasonable level of fire, safety and property protection that could be applied to all mines in varying degrees.

The facility that is the subject of this case study is the Sudbury Neutrino Observatory Laboratory, located on the 2,073-m level of CVRD Inco’s Creighton mine in Sudbury, Ont. SNOLAB’s underground expansion project will transform the observatory into the deepest, multiple experiment science laboratory in the world.

The existing lab houses neutrino experimental equipment, which measures and identifies neutrinos. The expansion will house additional experimental equipment including a cryogenic lab and various support services.

Descent to the lab from the surface is via a mine shaft elevator. The lab is approximately 1,220 m from the elevator via existing drifts approximately that are 3-m wide by 3-m high. There is alternate access from the surface to the lab through existing drifts.

The maximum occupant load for both the new and existing labs will be 70 people. Occupancy of the expansion is scheduled for April 2008.

The primary project team members involved in this study included:

* Carleton University — owner

*SNOLAB — facility operator

* CVRD Inco — mine owner/operator

*Acres — project manager

*Hatch — design engineers

*Ministry of Labour — authorities having jurisdiction

*Leber-Rubes — fire & life safety consultants

*J.S. Redpath — mining contactor

*Comstock — general contractor

Approach

There is no single code that specifically addresses the design and operation of a temporary or permanent underground facility of this type.

The Ontario Ministry of Labour and Occupational Health and Safety regulations typically address worker safety issues in mines and not the structure, the primary regulations being: Reg. 854 Mine Development (Mine and Lab Construction), Reg. 213 Outfitting/Construction (fit-up of lab space) and Reg. 851 for Industrial Occupancies (applies to the ongoing operation of the facility once occupied).

The Ontario building and fire codes address the structure, occupancy and operations of a building above grade and/or partially below grade. With this in mind, the overall approach to address the needs for fire and life safety are a combination of the requirements of these documents, while taking into account good engineering practice and operational procedures for this type of facility.

The building code does not have a separate occupancy classification for an underground laboratory; however, this type of activity would be considered a match for Group F, Division 2, Medium Hazard industrial operation.

Here are the safety steps that will be taken in the SNOLAB underground expansion project.

The labs will be separated from the remainder of the mine and each other by a fire separation system providing a minimum one-hour fire-resistance rating. This should include various compartmentalization doors in strategic locations to serve the access corridors (drifts) of the existing and new labs. The refuge room will be provided with a four-hour fire separation.

The facility will be constructed of non-combustible materials. This will include limits on the flammability ratings of wall finishes, wiring, piping, etc.

The existing fire alarm system will be replaced with a new system to cover the existing lab and the new addition. The new system will incorporate the following:

* audible signalling devices throughout,

* manual pull stations at one-hour fire separations and refuge room,

* heat detectors in the mine in the vicinity of entrance and exit to labs,

* heat detectors throughout the new and existing areas,

* smoke detectors in electronics and high value areas,

* strobe lights and horns at the two entrances from the mine, and

* sprinkler & standpipe flow and isolation valve tamper switches.

A standpipe and hose system will be installed. A dedicated bladder tank will provide a 60-minute water supply. A ULC-listed fire pump will be provided to boost the pressure.

Portable fire extinguishers will be installed throughout the lab in accordance with the Fire Code.

Provided the facility does not contain equipment with more than 100 L of flammable hydraulic fluids or storage areas containing more than 500 L of oil, grease or flammable liquids, sprinkler protection is not required. A sprinkler system flow and isolation valve tamper switches will be installed in the diesel generator area.

The building code and good engineering practice dictate that in an occupied space, two means of egress be provided. As this facility has only one access drift leading to the mine shaft elevator, alternate approaches are needed to ensure the safety of the occupants. The access corridors within the facility are very long. Compartmentalization will be used to address these lengths. Separating the corridors into one-hour fire compartments will help to ensure that occupants have enough time to safely exit into the drift. If a fire were to occur in the drift, occupants need to always have an alternate route to travel either to the mine shaft or to the refuge room within lab.

In the event there was a fire between the mine shaft and the lab, it might not be possible for occupants to evacuate the lab. As such, a refuge room needs to be provided. The refuge room will include the following:

* designed for at least 70 people,

* four-hour fire separation,

* compressed air supply,

* telephone communications with surface,

* potable water, and

* additional measures as per the emergency procedures, i.e., emergency lights, etc.

There is already a refuge room (maintained by CVRD Inco) between the lab and mine shaft. Either the emergency communications and compressed air lines will be designed to operate in the event of a fire, rock burst, flood, etc., or a back-up system capable of achieving this objective will be provided.

Combustible materials will be kept to a minimum at all times. Flammable gases will not be permitted to be stored in the lab areas. Oil, grease and flammable liquids with a flash point below 52oC will be transported and stored only in approved metal containers. For experimental purposes small quantities of flammable and combustible liquids will be permitted in the labs provided the materials are stored in approved flammable liquids cabinets. Experiments will only be conducted at approved workstations with the appropriate ventilation fume hood. A maximum of 100 L of flammable liquids will be permitted in the labs at one time.

A risk assessment will be done for any new experiments that use hazardous materials or that could create a hazardous situation. Existing emergency procedures will be modified and implemented as appropriat
e.

Provisions for the future installation of an emergency power system will be provided for the fire alarm system, emergency lighting, exit signs and fire pump.

Supply and return air ventilation systems for the facility will shut down upon activation of the fire alarm system. To ensure adequate air concentration levels are provided for the workers, O2, CO & N2 sensors will be installed and interlocked with the ventilation system where there is a possibility that the air could be contaminated, i.e., batteries, refrigerant, fuel, etc.

Revisions will be incorporated into the existing SNOLAB and CVRD Inco emergency procedures as appropriate for the facility. Special attention will be taken to ensure these documents will be integrated appropriately between the two groups. Any new experiments that involve hazardous materials or operations will be reviewed with the mine rescue team to ensure they are prepared for any incidents that differ from their existing emergency procedures.

Conclusion

Because of new production techniques and non-mining underground operations being conducted underground, the safety of miners and occupants from fire is no longer adequately addressed by existing regulatory codes.

The changes in mine use require that owners, operators, designers and authorities having jurisdiction re-evaluate some of their core design and operational approaches and philosophies. This is critical to ensuring a necessary level of fire and safety as well as property protection for these operations.

To achieve a final outcome with which all parties are comfortable, it is imperative that the preceding topics be addressed from the beginning of the design process.

George Fawcett is a vice-president and branch manager with Leber/Rubes Inc., a firm specializing in building code consulting and fire protection engineering. He can be contacted at tel. 613-247-1313 x23 or gfawcett@leber-rubes.com.