Canada's "Rock to Road" Magazine

All crushing and screening equipment at the secondary plant is
enclosed to reduce sound levels. The enclosure panels,
manufactured by Norseman Inc. consist of two layers of
industrial grade vinyl with integral sound absorbing material.

By Andy Bateman, Engineering Editor

   Extensive sound reduction measures and active community involvement are just two of the ways in which Calgary-based aggregate producer Burnco Rock Products Ltd. is setting the standard for fostering good community relations.
     At its main Indus pit south-east of Calgary, Burnco has taken the unusual step of enclosing both the primary and secondary portable processing plants to reduce noise emissions. Completed in 1997, this initiative is part of an impressive list of environmental protection measures that includes separate dewatering and wash water circuits, sequential overburden stripping and permanent sound level monitoring stations. On top of these, community relations initiatives include a number of voluntary financial contributions to the local community, access road paving and charter membership in a central truck registry system.

The primary crusher is fully enclosed by a purpose built precast concrete building to reduce noise. Sound insulation attached to the hopper canopy absorbs sound from discharging trucks.

     Kim Titus, manager of Burnco's Aggregate Division, explains that the original purpose of the distinctive plant enclosures was to reduce sound levels at the operation's closest neighbours, located some 800 m from the processing plant. The pit's primary crusher is fully enclosed in a purpose-built precast concrete building, while the secondary plant is enclosed by panels consisting of two layers of industrial grade vinyl with integral sound absorbing material. In practice, it was found that these measures not only delivered the required noise reduction, but also significantly reduced fugitive dust emissions. Building on this successful experiment, Burnco's three other portable spreads are now equipped with enclosure systems similar to the secondary plant.
     Located about 40 km south-east of downtown Calgary and six km from the city limits, aggregate production was carried out at Indus on a small scale prior to Burnco's acquisition of the property in the mid 1980's. Since then, demand for the pit's aggregates has been fuelled by Calgary's rapid commercial and residential development, particularly in the city's southeast and southwest quadrants.
     Covering some 445 ha (1100 acres) on a flood plain of the Bow River, the pit is worked dry by lowering the local water table some 3.5 m. To protect the water quality of the river, the dewatering system has its own self-contained circuit that is isolated from the circuit supplying water to the pit's wash plant. As a further precaution, all pumped groundwater is first discharged into intermediate holding ponds and tested before being pumped back into the river. The ponds are located in the floodway, a previously mined buffer zone between the extraction area and the river which forms part of the pit's ultimate rehabilitation back to pasture.

The Indus pit wash plant produces a full range of coarse and fine sizes for BurncoÍs area ready mix concrete and asphalt plants. All material arriving at the wash plant first passes through an Eagle Iron Works 914 mm diameter by 5.5 m long twin screw log washer.

     The stripping process here is completed in three stages in accordance with permit conditions. It begins with the removal and stockpiling of a surface layer of black topsoil about 150 mm thick, followed by the separate treatment of a 150 mm layer of subsoil. Finally, a layer of silty clay, varying in thickness from 2.5 m to 3 m, is removed to expose the underlying gravel. Titus reports that about 200 000 m3 of overburden is stripped and stockpiled annually under the company's dirt moving contracts.
     The coarse aggregate deposit here contains between 60 and 70 per cent material coarser than 4.75 mm, with occasional rocks as large as 750 mm.
     Primary loading is completed by two John Deere 330LC excavators, fitted with 2.3 m3 buckets and loading up to seven contracted tandem trucks. With a payload of about 18 tonnes each, the tandems have a typical haul of some 500 m. At the primary, a 30x40 Nordberg C100 jaw crusher reduces the pit run to 115 mm minus. Plant foreman Garry Derhak reports typical primary throughput of between 600 and 800 tonnes/h, or between 7000 and 8000 tonnes over a 12-hour shift. Noise reduction measures at the primary extend even beyond the full concrete enclosure. In addition, sound absorbing insulation has been attached to the canopy over the truck dump hopper and has proved to effective in absorbing sound emitted by haul trucks during the reverse and dump cycle.

The 36.6m long circular reclaim tunnel under the wash plant surge pile is a modified steel butane tank fitted with two in-house feeders.

     Downstream of the jaw, a 39.7 m long Assinck stacker, programmable for radial, luffing and extendable operation, stockpiles run-of-primary onto a surge pile providing about four shifts of live capacity. From there, material is conveyed to the enclosed secondary processing system consisting of three JCI 6x20 triple-deck screens, two Nordberg Omnicone 1560 crushers and associated conveyors. The first JCI screen directs material larger than 115 mm to a Torspec feeder which in turn supplies a coarse head Omnicone 1560 reducing the feed material to 38 mm minus. Meanwhile, material between 38 mm and 63 mm is reduced to 16 mm minus by a second Omnicone 1560, similar to the first except that this unit is fitted with a fine head. Product from the fine head is conveyed to the third JCI screen which separates 16 mm and 10 mm dry screened finished product. The 10 mm product is stockpiled by the operation's second Assinck programmable stacker, this unit being extendable to 42.7 m. Other sizes produced at the secondary plant include 40 mm by 28 mm drainage rock and 28 mm minus wash plant feed, also stockpiled by a 42.7 m Assinck programmable stacker. Largely hidden from view, the reclaim tunnel under the wash plant surge pile is an innovative example of equipment reuse; the 36.6 m long circular tunnel consists of a former steel butane tank which has been successfully adapted to this duty by the addition of two in-house feeders.

One of Burnco's two John Deere 330LC excavators loading a tandem truck. Up to seven contracted tandems are used to feed the primary plant.

     Located some 200 m from the secondary plant, the multi-stage wash plant incorporates a log washer, three screw washers and two triple deck wash screens, as well as a sand-classifying tank. All material arriving at the wash plant first passes through an Eagle Iron Works (EIW) 914 mm diameter by 5.5 m long twin-screw log washer. The initial 2 m section of the washer is fitted with paddles rather than helical screw section to break up any residual clay materials in the feed. Material leaving the log washer then passes over a Simplicity 6x16 triple-deck screen that divides the material stream into coarse and fine sizes. The coarse stream receives an additional scrubbing phase in an EIW 1.12 m diameter single-screw washer, before passing over a second Simplicity 6x16 screen that separates 28 mm, 14 mm and 7 mm finished product sizes.

Secondary cone plant is enclosed by vinyl panels to control noise and dust.

     Meanwhile, material finer than 5 mm is conveyed to a 10-cell EIW classifier separating 5 mm and 3 mm sand sizes. From there, 5 mm concrete sand is dewatered by a 1.12 m diameter EIW single-screw washer while the finer 3 mm mortar sand is dewatered by a 914 mm diameter EIW single-screw unit. Once inventories of mortar sand are sufficient, both sand fractions are recombined into a single size to maximize the plant's yield of concrete sand. For finished product loading, the wash plant features two bins whose clamshell discharge gates have timed opening to provide accurate product weights.
     In addition to the bins, wash plant product storage is provided by four shop-built luffing stackers Æ two 45.8 m long stackers stockpile 5 mm sand and 28 mm washed material, while two 36.6 m long units stockpile 14 mm and 7 mm washed sizes. Derhak adds that imported blend sand is added to the wash plant feed to balance the plant's output of coarse and fine sizes with demand from the company's area ready mix concrete and asphalt plants. The blend sand is introduced into the system by two 40-tonne capacity driveÆover bins, fitted with feeders to regulate its addition rate.
     Overall plant control at Indus is provided by two operators. The secondary plant operator monitors production in a Clemro control trailer, assisted by 13 cameras. Over at the wash plant, the operator has a high level view of the plant from the top mounted control room. Site materials handling and sales load out duties are performed by a fleet of three John Deere 744H front-end loaders, while a water truck works full time to minimise dust generation from loader and truck tires.

Inside the enclosure, a Nordberg Omnicone 1560 fitted with a coarse head reduces the plus 115 mm material to 38 mm minus.

     When it comes to repair and maintenance, the enclosures at the primary and secondary plants have been designed with easy access in mind. At the primary, a number of the precast wall and roof panels are fitted with lifting eyes to facilitate their easy removal and provide full access to the crusher. Gaining access at the secondary plant is faster still, as individual enclosure panels can simply be rolled back as required. For further flexibility, all of the primary and secondary processing equipment is trailer mounted and semi-portable Æ the jaw and both cone crushers are mounted on chassis supplied by WRT of Saskatoon, while the secondary screens are each mounted on a Clemro chassis.
     To ensure that the operation's sound reduction measures remain effective, two sound level monitoring stations have been set up near the property boundary and operate continuously throughout the production season. Titus reports recorded sound levels generally less than 55 dBA during running hours, numbers that compare favourably to City of Calgary noise bylaw levels of 55 dBA at night and 65 dBA during the day. Unlike many jurisdictions across the country, the pit's operating permit, including conditions on operating hours, is issued by the local municipality and subject to a public appeal process. As the permit is renewed for a maximum period of five years, the operation's track record is subject to public scrutiny on a regular basis. Titus reports that operating hours at Indus vary throughout the year up to the permitted maximum of 18 hours/day, with the pit normally shutting down for the winter months. As a footnote on permitting, Titus adds that the success of the noise mitigation and monitoring measures at Indus has enabled the company to increase operating hours from 12 to 17 hours at another company pit operation.

Wash plant product balance is optimized by the addition of imported blend sand utilising two driveÆover 40 tonne bins. Site materials handling and sales load out duties are performed by a fleet of three John Deere 744H front-end loaders.

     The company's community relations' efforts extend well beyond the property line at Indus. Each year the company makes a voluntary business licence fee payment of $30,000 to the Municipal District of Rocky View, with a further 25 per cent of this figure, $7500, contributed annually towards community programs. In addition, the company makes a number of corporate donations to local sports and charity programs. Other community projects have included two miles of paving on the pit approach road to further reduce dust generation, the result of a three-way shared effort between Burnco, the local Municipality and Alberta Transportation.
     Product delivery is recognised by Burnco as an integral part of the aggregate business, with the company implementing a number of measures to ensure good driving behaviour by truckers hauling product from the pit. These measures include the strict enforcement of posted speed limits on public roads near the pit and extra signs reminding drivers of the requirement for responsible driving.
     Further afield, Burnco and several other major aggregate producers in the area are able to quickly respond to public concerns on driving standards through a central truck registry system. Under the system, trucks are required to prominently display a registry reference number at the rear of each vehicle and, in the event of an incident, motorists can call a toll-free phone number, quoting the registry number. This can be quickly cross-referenced to the dispatch systems of member companies to provide full details of the truck, driver and specific trip being completed. Once these details are confirmed, the reported incident can be verified and any necessary follow up completed.

November 2002 issue

Aggregates and Roadbuilding Magazine
4999 St Catherine Street West. Suite 315
Westmount, Quebec H3Z 1T3
Tel: (514) 487-9868 Fax: (514) 487-9276
EMail: rocktoroad@sympatico.ca

Back to Library