Question of the Day - 30 May 2022

The problem isn’t sand so much.

Rather, it’s concrete-like caliche, a highly compacted layer of sediment, such as silt, clay, and/or gravel, that has been fused into calcium carbonate in arid areas, such as the Mojave, Sonoran, and Kalahari deserts. Caliche (a Spanish word derived from the Latin calx, or lime) is used in construction all around the world; with a good caliche, a mix of eight parts sand, nine parts caliche, and one part cement is adequate to make strong concrete. 

The Boring Company website gives the following answer to this question, under "Managing Excavated Dirt." 

"In typical tunneling projects, excavated dirt is shipped offsite to disposal locations. This process is costly, time-consuming, noisy, and environmentally unsustainable.

"We recycle a portion of the muck into bricks and pavers to be used to build anything from affordable housing to patios. This is not a new concept, as buildings have been constructed from earth for thousands of years, including, according to recent evidence, the Pyramids. These earth blocks can potentially be used as a portion of the tunnel lining itself, which is typically built from concrete. Since concrete production accounts for 4.5% of the world’s greenhouse gas emissions, earth blocks would reduce both environmental impact and tunneling costs."

We’re sure that, given population growth in the Las Vegas area, there’s plenty of demand for bricks. But how much of the soil displaced by Elon Musk is going into brickwork and other infrastructure we cannot say. The Boring Co. does not do media outreach, period. It’s company policy. We tried anyway, but our inquiry went unanswered.

We also threw a Hail Mary pass to the Sierra Club of Las Vegas; the PR person there was intrigued, but unable to help. 

Our eyes and ears are open to this question, so if we see or hear anything about it in the future, we'll be sure to let you know.