Septic effluent saturated shale and triggered a mass landslide at Portuguese Bend

Evidence

Around Los Angeles many homes are built upon hillsides and some of these locations are underlain with sheets of shale rock tilted seaward. When the underground shale is slicked with sewage effluent or too much lawn sprinkling, the loose earth above it may be inclined to slip downhill a bit. Since this is one of Nature’s ancient ways of leveling mountains, the leveling of a house is easy. The residents of Portuguese Bend, south of Los Angeles, learned this geologic truth the hard way. When the septic tanks of their new homes had saturated the shale beneath their 225-acre hillside community, everything began to respond slowly to the tug of gravity – lots, lawns, shrubbery, and 156 houses, each costing 25,000 to 50,000, gently slumped downhill as though they were so much custard pudding. — Adam Rome, The Bulldozer in the Countryside, 393

Categorization

• CANDY: One hundred fifty-six expensive houses sliding downhill ‘like custard pudding’ because their septic tanks slicked the underlying shale is a vivid, tweetable image of sprawl’s hidden costs.
• XREF: connects to: Septic-tank failures symbolized suburban baseness in 1950s cultural criticism — Adam Rome, The Bulldozer in the Countryside:…, 395