Eco-friendly renovationPublished 23/11, 2021 at 15:39
With decades of experience in new construction and commercial renovation, general contractor and construction manager Arguson Projects Inc. understood the logistical challenges posed by a multi-year, multimillion euro parking garage renovation project in Toronto’s East End.
The 39 year old structure needed to remain open while crews removed 18,581m2 of material from the second and third levels. Building tenants required parking to remain open, as well as continued access to the roof deck, which provided amenities for employees. Seizing an opportunity to reduce not only the project’s carbon footprint, but also the overall cost, Arguson, in conjunction with the property owner, turned to Conterra Restoration and a suite of Aquajet hydrodemolition equipment for an eco-friendly solution.
The suspended slabs within the parkade were heavily contaminated with chloride ions, or road salt, resulting in significant corrosion related deterioration and cracking. The concrete needed significant repair/replacement to address structural integrity concerns and overall aesthetics of the suspended slabs. Working with RJC Engineers, a Canadian based engineering firm specialising in parking facility design and restoration, Arguson determined hydrodemolition was the only concrete removal option that fitted the unique needs of the project.
“The main concerns for this project were noise and vibration generated by construction activity, as well as the vast amount of concrete that needed to be removed to properly rehabilitate the suspended parking slabs,” said Philip Sarvinis, P.Eng., managing principal with RJC Engineers. “Hydrodemolition allowed the contractor to work through the day without disrupting building tenants or the neighbouring properties, while at the same time removing large amounts of concrete. The process works extremely well with the added bonus that it doesn’t physically damage the remaining concrete left in place compared to traditional jackhammering operations.”
Arguson brought in Conterra Restoration, a contractor with extensive hydrodemolition experience. Conterra sourced an Aquajet ‘Aqua Cutter’ 710V from Cor-Blast Services Inc. which could provide more productivity than a large crew using conventional equipment. The 2,350kg robot uses a water jet which removes concrete by widening existing pores and micro cracks in the weakened structure. Since the process is impact free, there are no vibrations, and therefore less risk of micro fractures. The plan also featured a quiet Aquajet 700 ‘Ecosilence’ high pressure pump. “With the Ecosilence, the pump and diesel engine are inside a container with this machine, which dampens the sound enough you could run it under a window downtown and still be quieter than normal traffic,” said David Porciello, general manager for Conterra. Additionally, the Ecosilence allowed Conterra to work throughout the year, even when temperatures hit -20C. The contractor also included an ‘EcoClear’ water treatment system as part of their tender for on-site water treatment in real time. After passing through the EcoClear, wastewater can be released into the sanitary sewer system.
“Environmental stewardship has always been an important part of the conversation for us,” Porciello said. “With the Aquajet equipment we saw an opportunity to not only provide fast, high quality results, we could also drastically reduce our impact on the environment. From eliminating the gas and exhaust of vac trucks to minimising crews and the associated emissions getting them to and from the worksite, we were able to present not only an economic solution, but an eco-friendly one as well.” In addition to hydrodemolition, Conterra bid for subsequent phases of the project including pouring new concrete, applying a waterproofing system and painting lines.
The project was broken into two phases over two years, commencing in December 2019. Conterra set up a staging area outside the parkade for the Ecosilence and EcoClear with Arguson and Conterra having a dedicated crew of workers and subcontractors on-site with a small contingent running the Aqua Cutter and support equipment. The hydrodemolition removal process is monitored by one operator/technician with some assistance monitoring the EcoClear. Additionally, a team follows up behind the robot to remove the demolished concrete. Other crews are employed removing through slabs, forming and other tasks throughout the site. For the most part, the robot removes concrete to a depth of 100mm to 130mm.
“The Aqua Cutter finds what most engineers can’t every millimetre of bad concrete,” Porciello said. “The robot can be programmed to remove a certain depth; however, the removal could be deeper in certain areas if the strength of existing concrete is not adequate. This assures that all deteriorated concrete is removed and a sound substrate remains for superior bonding of the new concrete overlay. This gives us a clean slate of good concrete for stronger, longer lasting repairs.” During an 8h shift, Conterra sees removal rates of 55.7m2 to 92.9m2.
Working with water
Water is routed through existing drains and a system of clear stone filtration to a catch pit near the staging site. From there, it is pumped through the EcoClear which can process as much as 20m3/h on its way to the sewer. “The EcoClear system gave us a distinct advantage for this project,” Porciello said. “We’re the only group in Ontario with equipment that can provide documented, quantifiable results on-site and on demand. With these amounts of water, we didn’t even consider alternative treatment methods. The carbon cost was just too great.” With the EcoClear, Conterra can reduce blast water pH from 12.5 to between 7.5 and 8.5. The system uses carbon dioxide rather than mineral acid to reduce pH. This eliminates the risk of acidifying the water and requires less in the way of oversight, training and PPE. The EcoClear also reduces suspended solids to 50ppm or less. “We’ve gotten as low as 15 ppm,” said Porciello.
“Hydrodemolition put us on the cutting edge of industry trends,” Porciello said. “With hydrodemolition robots, we’ve been able to adapt quickly. This speaks to how manufacturers like Aquajet listen to their customers and plan for the future of construction. From eco-friendly solutions to eliminating silica dust to reducing health risks like white fingers and hearing loss, smart equipment developments keep us ahead of the curve.”
Case short reach excavator delivers sustainable
Case dealer Robert Coates Plant Sales Ltd recently sold a CX245DSR excavator fitted with a ‘Powerhand’ VRS 200 recycling system to Moores Metals which has been providing scrap metal recycling services since 1911. Robert Coates’ sales manager Richard Parry explains: “They needed a zero tail swing excavator able to operate on a congested site with an attachment nimble enough to extract wiring looms and starter motors.” Moores Metal’s Andrew Burkinshaw adds: “In the changing landscape of vehicle dismantling, our new Case CX245DSR excavator allows us to segregate different metals for resale. Overall, the solution is more sustainable because separating out metals and plastics means that the materials that remain at the end of the process will be cleaner.”