Parts of San Rafael, a city north of San Francisco, are sinking about half an inch a year. That might not sound like a lot, but overall, it means some neighborhoods — like the Canal District bordering the bay — have sunk three feet, putting them at greater risk of flooding from sea-level rise.
San Rafael is not alone. Cities around the world are threatened by rising sea levels, with 300 million people at risk from routine flooding by 2050. Costs of building sea walls to hold back waters could peak 400 billion dollars only in the US.
A new startup is proposing an alternative: to raise the city instead.
Terranova is building robots that will pump a slurry of wood waste into the ground, slowly lifting the earth to eliminate historical subsidence and hopefully prevent these areas of the city from flooding.
“The canal area is really far below sea level,” Laurence Allen, co-founder and CEO of Terranova, told TechCrunch. The city is working with flood advisors to find a solution, he said.
“The answer, every answer every time, was about $500 million to $900 million of sea walls, which if you’re from San Rafael, you know they can’t even afford it. There’s about 60,000 people, and a significant portion—surprisingly for a city in Marin—lives in poverty.”
Terranova says it can protect San Rafael and other cities like it for a fraction of the cost. In the case of San Rafael, the startup quoted $92 million to raise 240 acres four feet.
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The company recently raised $7 million in a seed round led by Congruent Ventures and Outlander with participation from GoAhead Ventures, Gothams and Ponderosa, according to TechCrunch exclusively. The oversubscribed round values the company at $25.1 million.
Land lifting by injecting material underground is not new. Terranova’s pitch is that it has developed some new approaches that make it cheaper.
First is the material: Scrap wood is cheap and easy to obtain. The startup mixes it with other ingredients it wouldn’t disclose to turn it into a slurry. The output is pumped from a 20-foot shipping container into the second type of cost savings: a robotic injection device. Tracked robotic units autonomously roam around the construction site, drilling wells through which wood pulp is delivered to depths of about 40 to 60 feet.
As long as the pulp stays moist underground, the wood shouldn’t decompose, and the company can sell carbon credits to offset the cost, Allen said.
All of this is managed by software developed by Terranova. The company uses public geographic information combined with data from cores drilled throughout the state of California, taken primarily during water well construction. With this, it has created a model of the subsurface that informs the injection patterns, which are determined by a genetic algorithm.
On the back end, city planners, contractors and other stakeholders can use a SimCity-like tool to sculpt the virtual landscape.
When the designs are finalized, they guide the robotic injectors, telling them where to inject and how much. Human operators remain on site as a safety precaution, Allen said. Once the robots are done injecting, it takes about two hours for the slurry to solidify, he added.
Terranova has been testing both the robots and the software at a pilot site for more than a year, he said.
Although some experts have questioned whether consolidated wood sludge will worsen earthquakes, Allen said the most commonly cited alternatives also have risks. “We think it will help [with earthquakes] against dykes and sea walls”.
The company plans to make money by sharing revenue for projects with contractors. He hopes the cost is low enough to make the process attractive for a range of land-raising projects beyond cities, including restoring wetlands that are disappearing either due to subsidence or sea-level rise.
But given the urgency of the rising waters, cities are Terranova’s first priority. “I’m from San Rafael, born and raised,” Allen said. “I really want to save the city.”
