With sweeping views of San Francisco Bay and the iconic Golden Gate Bridge, it’s no wonder teenagers, thrill seekers and, more recently, Instagram users have been sneaking onto the grounds of Belvedere’s Lava House for decades. Trespassing on the four waterfront lots has become somewhat of a rite of passage for local youth. But deterioration of the concrete and lava structures and limited site access for emergency responders led to increased concerns for public safety in recent years. So, in 2018, the property’s trustees decided to work with Belvedere officials to remove the crumbling construction.
Demolishing the abandoned structures and stabilizing the landslide-prone cliff face would require a creative contractor, though. Steep terrain and a narrow site ruled out the use of large excavators. Handheld equipment was an option, but a time-consuming, dangerous, and expensive one. Jamba Construction, a company with a reputation for unique and complicated projects, was tasked with finding a safe, efficient solution. Excited for the challenge, Jamba turned to a revolutionary process gaining traction in the construction industry—robotic demolition. The innovative machine provided the hitting power they needed with a much smaller footprint than traditional excavators, and its remote operation kept workers out of harm’s way.
ABANDONED LEGACY
The history of the Lava House has as many twists and turns as the tunnels, passageways and rotting stairs that remained after a landslide halted construction in 1982. Jerry Ganz, a Midwestern entrepreneur who found fame as the original mass-marketer of automobile seat belts, bought four adjoining waterfront lots with terrific views of the Bay Area on the exclusive Belvedere Island.
The city refused permit requests for Ganz’s original 30,000-square-foot mansion, so construction began on a smaller 16,000-square-foot home. Ganz imported more than a thousand cubic yards of lava rock from Hawaii to create intricate gardens and design features. The material inspired the structure’s unique name. After 10 years of steady construction, however, severe flooding and site instability caused Ganz to abandon the project.
Starting in the early 1980s, a series of fences were erected to keep trespassers off the deteriorating structures—with limited success. Ganz remained involved with the property for several decades before stepping back and leaving the ruins of the Lava House to a trust overseen by family members and associates. To the relief of neighbors and first responders, Ganz and the trustees opted to work with city officials to remove the crumbling structures.
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. Over the years, it built a solid reputation for problem solving, working on some of the most unique and challenging buildings in the area.
“We gravitate toward projects that require us to be innovative and to try new things,” says 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.”
AT THE CLIFF’S EDGE
Jamba’s first challenge was finding equipment that had the power to demolish reinforced concrete and lava but was small enough to maneuver on the site’s steep terrain.
“Access to the site was our biggest hurdle,” Swanson says. “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.”
Removing an estimated 1,000 cubic yards of debris was the easy part. Jamba contracted a landing craft to deliver a track 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, as well.
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. A narrow, two-lane road running across the top of the four lots created almost 400 linear feet of road access, but a low rock wall fronted the property along most of that length. Additionally, a 60-degree incline just off the shoulder restricted access for larger equipment. In the end, Jamba could only identify one 8-foot section with the access and tie-off points necessary to safely lower equipment 150 feet to the jobsite below. Everything else, including personal vehicles, had to be parked at the top of the cliff.
Doing the whole job using handheld pneumatic devices was also rejected by Swanson and his team. With more than 2,000 yards of material to be demolished, Jamba estimated it would take an additional 3 months and $150,000 to complete the job with hand tools alone. There was also the human cost to consider. Jamba couldn’t discount the risk to its workers that the difficult site conditions and long hours with handheld breakers could cause.
“We knew there had to be a solution out there,” Swanson says. “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 4.5-ton excavator but only weighed 1.76 tons. The demolition robot’s compact design was perfect for tackling the Lava House’s narrow passages and complex architecture. Jamba partnered with a third party to operate a single Brokk 160 at the Lava House jobsite—the first phase of the 10-month project.
OVER THE EDGE
The demolition of the Lava House had been relatively under the radar of the Belvedere community until February 2019 when Jamba closed off one of the island’s major roads to lower the Brokk 160 to the jobsite. Working in tandem with a 25-ton tow truck parked on the road, it took about 2 hours to maneuver 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 maneuverability of the Brokk machine really made the descent easier,” Swanson says. “The articulation in the arm allowed the operator to put the breaker tip down and stabilize 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 realized 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 track 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 stabilize it, the Brokk operator hammered away at the main structures. The Brokk machine was able to produce 600-foot pounds of hitting power at up to 1,400 blows per minute using a SB202 breaker. The Brokk operator started demolition on the roof of the garage and steadily worked his way down, creating paths out of debris for the robot to maneuver to the next demolition area.
In a month, the Brokk machine demolished 1,200 cubic yards of concrete and lava, completing 60 percent of the overall demolition. Using the Kubota track loader and MB-L140 crusher bucket, Jamba crushed 1,000 cubic yards of concrete and lava for backfill to stabilize the site. An additional 1,000 cubic yards—along with 200 cubic yards of steel, wood and other materials—were removed by barge and trucks to recycling facilities in the Bay Area.
With the completion of phase one, the Brokk 160 was demobilized from the site and winched back up the slope. While they waited for cooler fall temperatures to start the landscaping phase of the project, Jamba completed demolition and debris removal with supplementary equipment.
CLOSING THOUGHT
The Lava House’s iconic structures might be gone, but the million-dollar views remain. In less than a year, Jamba Construction demolished over 1,500 cubic yards of concrete, lava, steel, wood and debris. And, in true California fashion, most of it was 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.”
For More Information:
Jamba Construction is an award-winning general building and engineering contractor experienced in the construction of fine custom homes, estates and other innovative construction projects. The company also specializes in complex drilling, demolition and site engineering projects. Jamba has cultivated a reputation for completing projects that require ™out of the box∫ innovation and planning. For more, visit www.jambaconstruction.com. Brokk has been the world’s leading manufacturer of remote-controlled demolition machines and attachments for more than 40 years. For more, visit www.brokk.com.
Modern Contractor Solutions, October 2020
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