Maple GO Transit

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Fully Monitored Wall Meets & Exceeds Expectations for MTO Demonstration Project


GO Transit, the public transit service for the Greater Toronto and Hamilton areas, planned an ambitious parking expansion project at the existing Maple GO Station in Vaughan, Ontario. A large 6m high, 300m long retaining wall was specified in order to maximize the
usable parking area.

Based on several, past successful projects with GO Transit, Risi Stone Systems provided a full wall design utilizing the SienaStone System. The wall contract was awarded to Regent Landscape, one of the GTA’s premiere Wall Builders with over 30 years of experience.

This SienaStone wall was constructed in two phases, with the first being a 100m section that required additional foundation replacement and improvement due to poor site conditions. Use of geotextiles and high quality imported fill was mandatory to achieve the bearing capacities stated in the Design. To ensure the minimum 150 kPa allowable Bearing Capacity below the wall, the Site Geotechnical Engineer recommended OPSS Granular B fill material be compacted to 98% SPD in the designated areas. Because the “Wall” is not limited to just the SienaStone facing units, but is in fact the entire Geogrid Reinforced structure, it was necessary to redevelop the foundation for the entire width of the reinforced zone, plus an additional 60cm in front and behind. This is an effective method of reaching the “competent” founding elevations without increasing the height of the Wall. 

Prior to the construction of the remaining 200m of wall, it was decided that this wall would be utilized as demonstration project by Risi Stone Systems and Unilock to advance the SienaStone product on the Ministry of Transportation Designed Source for Materials (DSM) List from the existing status as a “Non-Reinforced” wall to a Geogrid Reinforced System. 

The MTO specifications required that the SienaStone product meet a minimum compressive strength requirement of 40 MPa. Research done by the NCMA (National Concrete Masonry Association) has shown that the compressive strength of a block is directly related to its long term durability and freeze-thaw resistance, particularly in cold climates. 

As part of the approval process, the MTO also requires the demonstration project to be regularly monitored (every 2 months) following construction for a period of 1 year to observe any settlement or movements that may occur. The size and scale of the GO Transit project was ideal for the type of structure the MTO would consider, so detailed monitoring began shortly after construction. After a year round survey & monitoring program, the SienaStone wall performed beyond expectations, with little to no movement observed. The maximum movement on the 6m height was in the range of 3mm-4mm, which is considered to be within measuring tolerance by the Surveyor. 

This level of performance is a testament to the Contractor’s thorough quality control and construction practices, which are as important as any aspect of the design or engineering, as well as the stability and dependability of the SienaStone wall system.


VIVA Transit York Region

Printable PDF version › RisiStone_CS-Viva


Collaboration on major transportation initiative in York Region


The Regional Municipality of York is a vibrant and rapidly growing collection of 9 municipalities located just north of Toronto, Canada. No longer seen as Toronto’s “bedroom communities”, York Region has become one of Ontario’s premier locations for living, working, and playing. With over 1 million residents today, and expectations to
grow to almost double that by 2041, the York Region Transit Authority has embarked on an ambitious multi-year master plan to create a smooth, efficient and seamless transportation network that will keep people moving and growth sustainable. 

A cornerstone of the new vision for York Region transit is the bus rapid transit service, also known as VIVA.  As part of the YRT Master Plan, the “VIVAnext” Project was launched in 2008 with the goal of transforming the main service corridors using a concept known as “Rapidways”.  Rapidways are dedicated bus lanes running down the center of the road that feature “realtime” information displays, state of the art shelters, and most importantly, fast and reliable service. However, the transformation of these corridors was much more than a simple road widening. The bold VIVAnext vision included pedestrian friendly, tree lined boulevards, open spaces, and green landscapes – a true model of urban design for the future. 

In many cases, to accommodate the construction of these dedicated center bus lanes and pedestrian boulevards, the existing roadways needed to be widened substantially, often creating grade differentials requiring retaining walls.  Based on our long and proven track record in the industry, Risi Stone Systems and Unilock were invited to participate in the initial Design discussions to evaluate the structural requirements of the various sites, assess the visual and aesthetic goals of the Designers and help facilitate a solution. 

The first phase of the VIVAnext Project was the transformation of Davis Drive in Newmarket. Home to the world renowned Southlake Healthcare center, this high profile corridor was designed with serious consideration given to modern, urban aesthetics, attention to detail, and overall harmony of all Design elements. 

Unilock’s industry leading, Umbriano® paving stone system was chosen for the pedestrian boulevards, standing aprons for the glass and steel bus shelters, and the many sidewalks and walkways throughout.  With clean edges and cut granite appearance, Umbriano provided the contemporary look the VIVA Designers were after, with the durability required for high traffic, public areas.  As part of the overall site drainage plan, Unilock’s Eco-Priora permeable paving system was also used in specially designed locations to collect and store surface water and create a more environmentally sustainable landscape (check out these paving stone systems at

For the Retaining Walls, a number of strict structural requirements and limitations led to the selection of the SienaStone® system. Given the complexity of utilities, other structures, and property line/ROW constraints in and around the retaining walls, the use of tie-backs or geogrid reinforcements was not an option. With SienaStone being a multi-depth system, the Risi Stone designers were able to devise site specific “gravity wall” solutions using the larger SienaStone 925 units (925mm in depth) to avoid the use of additional tie-backs (Siena Stone gravity walls can be designed to exceed 3.0m in height depending on conditions). To economize, a mixture of 925 units (closer to the bottom of the wall), and standard 500 units were utilized optimally.  Finally, the pedestrian handrail was required to be mounted directly into the Wall, which the mass of the SienaStone system can accommodate. As an MTO (Ministry of Transportation Ontario) approved Wall System, SienaStone provided the level of confidence needed by the Structural team at VIVA.

From an aesthetic point of view, given the popularity of the “linear” look in Architecture and Landscape Design today, the large scale (1200mm in length x 185mm in height) rectilinear SienaStone units blended well with the overall design concept. 

Another key component to the Wall Design was the inclusion of a custom “VIVA” Coping Unit (Top Course). In keeping with other Design elements on the Project, the VIVA team wanted a more architectural looking, smooth faced Coping. Working in collaboration with VIVA, Risi Stone developed a new Coping unit that included  modern, clean lines, a smooth (two-sided face) and subtle chamfers on the front and back of the block. After reviewing full scale prototypes, the VIVA team approved the new Design and a custom mold was ordered for the Project. To enhance the look of the Coping, and provide greater contrast with the SienaStone wall, a custom mix design was created by Unilock that used white cement and a finer aggregate. This level of attention to detail and scrutiny was typical of the VIVA design approach. From the new Architectural Siena Coping to the custom handrail with distinctive IPE wood top rail, great consideration was taken to ensure the structural, aesthetic and functionality of all elements worked together – and the results speak for themselves.

With the Hwy 7 corridor in Richmond Hill/Markham completed, VIVA reports that tremendous commuter time savings have already been realized and ridership has increased substantially, not to mention the profound change in the appearance and functionality of these areas. 

The collaboration with the VIVA Design Team is an example of how early consultation with Risi Stone and its partner manufacturers such as Unilock can lead to a smooth, well informed and ideal design process.


Fort McMurray • SienaStone in the Canadian North

Printable PDF version › RS-CS_FortMcMurray

Fort McMurray SienaStone Case Study

Under budget and on-time, this major SienaStone project in Fort McMurray Alberta is a testament to what is possible when you combine one of the most experienced and knowledgeable Commercial Wall Builders in the Province with one of the most proven Wall Systems on the market.

The Situation

The Canadian North is well known for its harsh, unforgiving winter conditions and rugged landscape. When Commercial Wall Builders Com-Con Paving Stone Ltd. began assessing the logistics and feasibility of installing over 5,500 sq.m (59,000 sq.ft) of Wall in Fort McMurray, Alberta, their 40 years of experience told them that weather, time and manpower restrictions would all be major factors. It was clear that speed of installation was critical, as well as the ability to machine place the Wall System, given the labour shortage in the area at that time. At over 200 kg (450 lbs) per unit (500 Standard), the SienaStone Wall System, manufactured by Expocrete Concrete, fit the bill. The SienaStone System is a machine laid, solid block Wall that can be installed at a rate of up to 100 sq.m (1000 sq.ft) /day with a 3-4 man crew. With machine placement, Contractors know that the rate of installation stays relatively constant all day long as it is not subject to worker fatigue.

The Site

Known as the Eagle Ridge Subdivision development, the Site consisted of a rolling landscape, necessitating substantial retaining walls for functional and aesthetic purposes. The installing Contractor, Com-Con, worked closely with the development Owner, Centron Residential Corporation, and the Site Geotechnical Engineer and Wall Designer, Brad Ellingwood, P.Eng., of E2K Engineering Ltd ( to address the many logistic and site issues typical to a project of this magnitude.
Given the residential nature of the development, aesthetics were also an important factor in the Wall product decision. With its linear, chamfered appearance, SienaStone strikes a balance between providing heavy duty performance, with a “non-commercial” aesthetic.
In some areas, the Site Plan design facilitated access to walking paths, an ecological reserve, and residential properties using intermittent in-set Siena Stone stairways, an application the unit height of SienaStone is ideal to handle.

The Details

Over the life of the contract, many changes were made “on the fly” for aesthetic and logistic reasons by the Owner. The scope of work was altered to include placement of loam, gravel and other materials to accommodate the owners’ progressive development, in addition to the installation of the retaining wall. With clear communication between all parties established early on in the Project, Com-Con was able to provide dynamic, flexible solutions to whatever site modifications where necessary.
As this particular site allowed for sufficient space behind the wall for geogrid reinforcement, Walls were designed using the 500 Standard SienaStone Block. This project was completed utilizing a four (4) man crew. Installation sequence and methods were streamlined to produce the walls efficiently and effectively, averaging approximately 600-800 sq.ft per day. Delivery of materials was timed in order to minimize the stockpile areas and ensure steady daily progress.
In the end, Com-Con completed this project 15% under budget, with the result being an amazing example of quality workmanship, heavy duty performance, and great Design.

The Installer

Com-Con was incorporated in May of 1976 as a family business with Reinhard and Werner Moellenbeck. At that time, paving stone installation was rare in Western Canada. The brothers worked with several different companies demonstrating their vast knowledge of paving stones and proper installation techniques. Reinhard collaborated with a local concrete manufacturer to develop their plant to produce paving stones in varying sizes and shapes allowing for more decorative and patterned placement. In 2006, Reinhard’s son Jason joined the company bringing his expertise as a Landscape Architectural Technologist. Jason purchased the company from his father in 2008, and has since propelled Com-Con to be one of Alberta’s premier Commercial Wall Builders. Com-Con has firmly established a reputation of projects completed on-time and on-budget, with impeccable work ethic and installation techniques.

Congratulations to Com-Con on over 40 years in business!


West London Dyke

Printable PDF version › RisiStone_CS-London_Dyke


This project is part of a large-scale reconstruction of the existing dyke system along the Thames River in London, Ontario. In this phase,approximately 300m (1000ft ) of the dyke was replaced with a new 8m (26ft ) high DuraHold wall.

Extreme 2 year and 75 year flood events in the Thames River have the potential to completely submerge the entire new wall. Due to the rapid fl owing hydraulic conditions, the DuraHold product was used because its smooth surface reduces drag eff ect from fl owing water. This, combined with DuraHold’s structural stability, high rate-of-installation and the capacity to create curves with its Tapered Half units, made it the ideal choice for this project.

With the river limiting site access, and the necessity to prevent contamination of the Thames River, all construction had to be completed from the high side of the wall. Proper coordination of the excavation, block placement, and infi ll material was crucial because of the limited space. Due to the height of the wall, a fall arrest system was utilized, with anchor wires secured to large blocks. Workers could then harness themselves to the wire allowing the range of movement required to construct the wall.

The complex space constraints and additional factors of the site made excavation and fi lling operations diff icult and consequently reduced the installation rate to approximately 45m2 (484ft 2) per day. Under ideal conditions, machine-placed wall systems can be installed at much higher rates (100–150m2 per day [1076–1614ft 2]). However, because machine-placed walls do not rely on the physical capacity of the workers to place the block, the rate of installation was maintained at the same level throughout the day.

A reinforced toe wall that was constructed to stabilize the original dyke in the 1980’s, was used as erosion protection. It was cut to fit the new wall layout and riprap was placed between it and the DuraHold wall. To allow for the water to exit the infi ll zone as quickly as possible following a fl ood event, the wall was backfilled with a 60cm gap-graded drainage layer. Drainage tiles were installed at grade, and fl ood event elevations, with the drainage tiles outlet through the wall face at 15m intervals.



On the North end, a 90 degree “hidden wall” was incorporated into the layout with a curved section abutting it. This new curved section reduces fl ow turbulence and allows the wall to taper back into the existing dyke structure. The “hidden wall” permits for a future planned expansion and will eliminate the need to dismantle a large portion of the new wall. Simply by removing the curved section and abutting to the “hidden wall”, the wall can quickly and easily be extended.

A pathway running alongside the Thames River was incorporated into the layout atop the new DuraHold wall. The South end of the wall was terraced, allowing the pathway to extend down under the Queens Ave. and Kensington Bridges, and connect to Riverside Park.