Builder finds robotic solution for historic demolition projectPublished 21/4 at 14:20
Located near San Francisco Bay and the iconic Golden Gate Bridge, Belvedere’s Lava House has proved iconic, but deterioration of the concrete and lava structures have led to increased concerns for public safety in recent years. This led in 2018 to the property’s trustees deciding to work with Belvedere officials to remove the crumbling construction.
Demolishing the abandoned structures and stabilising the landslide prone cliff face would require a creative contractor, with steep terrain and a narrow site ruling out the use of large excavators. Jamba Construction, a company with a reputation for unique and complicated projects, was tasked with finding a safe, efficient solution. Jamba chose to use robotic demolition from Brokk, which provided the hitting power needed with a much smaller footprint than traditional excavators, with its remote operation keeping workers out of harm’s way.
Up for the challenge
Jamba Construction arrived to begin demolition in early 2019. The award winning local company has 14 years of experience in high end home construction. “We gravitate toward projects that require us to be innovative and to try new things,” said Mark Swanson, owner and president of Jamba Construction. “Over the years, that has resulted in a team of creative problem solvers and a whole host of service offerings I never would have expected. Small scale demolition has been part of the initial phase of several projects, but the Lava House presented us with something we’d never done before - a complex, large scale demolition on inhospitable terrain with practically no access. It required a brand new approach.”
Jamba’s first challenge was finding equipment that had the power to demolish reinforced concrete and lava but was small enough to manoeuvre on the site’s steep terrain. “Access to the site was our biggest hurdle,” Swanson said. “The property makes for an amazing view, but a bit of a logistical nightmare when you need to arrange for equipment. We had two choices: by land or by sea, and neither one of them would be easy. Everything was just too steep to bring in any type of heavy equipment.”
To remove the large amount of debris Jamba contracted a landing craft to deliver a tracked loader with a grapple attachment and a ten wheel dump truck to the beach area of the site. Materials and debris were then removed over the water and across San Francisco Bay. The actual demolition would be bit more difficult, though. The landing craft was not large enough for the cranes or bigger excavators Jamba needed. Even if the company could land larger equipment, there was no way to traverse the steep terrain and gain access to the demolition site. The narrow waterfront and difficult currents would make it nearly impossible to moor a barge or platform.
Getting equipment to the site from land presented Jamba with another set of challenges that limited its equipment choices. Due to landslides and deterioration, there was no driveway or clear path to access the site preventing Jamba from simply driving in equipment. In the end, Jamba could only identify one section with the access and tie off points necessary to safely lower equipment. Everything else, including personal vehicles, had to be parked at the top of the cliff.
As to what type of equipment, Swanson comments, “We knew there had to be a solution out there. We were looking at mini excavators in late 2018 when we came across Brokk on the World of Concrete website. It was perfect. Almost too good to be true.” When he contacted Brokk’s regional sales team, Swanson was happy to find the Brokk 160 remote controlled demolition machine could provide as much hitting power as a 4.5t excavator but only weighed 1.6t. The demolition robot’s compact design was perfect for tackling the Lava House’s narrow passages and complex architecture.
Over the Edge
Working in tandem with a 25t tow truck parked on the road, it took about two hours to manoeuvre the Brokk machine down the hillside. The remote controlled demolition machine was attached to the truck’s powerful winch to keep it from tumbling down the steep incline. Standing safely on the road, the Brokk operator used the remote control to clear the machine’s path as it descended. “The manoeuvrability of the Brokk machine really made the descent easier,” Swanson said. “The articulation in the arm allowed the operator to put the breaker tip down and stabilise the machine if it was getting a little off balance on the slope. He was also able to break up any obstacles like roots, stumps or rocks that could cause it to tip. As we watched it move down the hill, we realised even if we had found a mini excavator with enough power, the Brokk gave us more flexibility.”
With the path cleared, Jamba was able to lower additional equipment down to the jobsite including a Kubota SVL-75 high flow tracked loader with MB-L140 crusher bucket and Kubota KX040 9000lb mini excavator with demolition hammer. While Jamba’s crew worked to clear paths and backfill areas of the landslide prone site to stabilise it, the Brokk operator hammered away at the main structures using a SB202 breaker. “For the most part, we let the Brokk machine handle the buildings while crews used mini excavators and handheld pneumatic tools to clear away smaller debris,” Swanson said. “It worked out perfectly; it kept the crew and equipment away from the more dangerous demolition areas and we were able to get more done while the Brokk operator handled the heavy hitting.”
In a month, the Brokk machine demolished 400m3 of concrete and lava, completing 60% of the overall demolition. Using the Kubota loader and MB-L140 crusher bucket, Jamba crushed 300m3 of concrete and lava for backfill to stabilise the site. With the completion of phase one, the Brokk 160 was demobilised from the site and winched back up the slope. In less than a year, Jamba Construction demolished over 500m3 of concrete, lava, steel, wood and debris, with most material being recycled. “This project presented us with some exciting challenges,” Swanson said. “It also gave us a chance try out new technologies. We’re looking forward to more opportunities like this one.”