High-End Builder Finds Robotic Solution for Historic Demolition Project
Belvedere’s Lava House, an unfinished and abandoned mansion with amazing views of San Francisco Bay and the iconic Golden Gate Bridge, was an irresistible draw for teenagers, thrill seekers and, more recently, social media users looking for an Instagram-worthy shot. With safety concerns mounting from deterioration and limited site access for emergency responders, though, property trustees stepped in to remove the iconic construction and stabilize the landslide-prone cliff face 2018.
Jamba Constrcution was tasked with finding a safe, efficient demolition solution. Steep terrain and a narrow site eliminated the option of large excavators and relying on smaller pneumatic equipment to demolish an estimated 1,000 yd3 (764.5m3) of concrete would be time consuming, dangerous and unnecessarily expensive. Jamba turned to a revolutionary process gaining traction in the demolition industry — robotic demolition.
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 as well as to remove debris by sea. The actual demolition would be bit more difficult, though. The narrow waterfront and difficult currentsmade it impossible to bring in the equipment necessary to work from below. Accessing the property by land was also a challenge. Due to landslides and deterioration of existing structures, there was no driveway or clear path to access the site, preventing Jamba from simply driving in equipment. Jamba was forced to come up with a creative solution to lower equipment from the street above. A narrow, two-lane road running across the top of the four lots created almost 400 ft (122m) 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, Swanson and his team could only identify one 8-ft (2.4m) section with the access and tie-off points necessary to safely lower equipment 150 ft (45.7m) to the jobsite below. This meant they would need to find a small machine with the hitting power of a much larger excavator.
So, Jamba partnered with a third party to operate a BROKK 160 remote-controlled demolition robot at the Lava House jobsite for one month. The demolition robot’s compact design and hitting power — comparable to that of a 4.5-ton excavator — was perfect for tackling the narrow passages and complex architecture.
After a thrilling descent where the Brokk operator worked in tandem with a 25-ton tow truck to lower the Brokk 160 to the jobsite, Jamba was ready to start the demolition phase of the 10-month project. Jamba crews worked to clear paths and backfill areas of the landslide-prone site to stabilize it while the Brokk operator hammered away at the concrete and lava structures.The Brokk machine was able to produce 300 lbf (1,334N) 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 level.
In one month, the Brokk machine demolished 11,200 yd3 (917.5m3) yards of concrete and lava, completing 60% of the overall demolition. Using a MB-L140 crusher bucket, Jamba crushed 1,000 yd3 (764.5m3) of concrete and lava for backfill to stabilize the site. An additional 1,000 yd3 (764.5m3) — along with 200 yd3 (153m3) of steel, wood and other materials — were removed by barge 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.
In less than one year, Jamba completed the multi-faceted demolition project. And, while the Lava House’s iconic structures might be gone, the million-dollar views remain.