Water leaks cause a slippery slope, major damage to California mansion


Replacing failed vertical seepage pits is a common job for Bob Willis of Bob’s Septic Service in Escondido, California. He expected nothing unusual when three 11-year-old pits failed on a mansion built into a Rancho Santa Fe hillside.

The homeowners reported consecutive months with $1,300 and $1,700 water bills. Plumbers had located and repaired the leak, but not before it hydraulically overloaded the 4-foot-diameter pits.

Willis’s crew drilled three 70-foot-deep seepage pits at the opposite end of the property to preserve the landscaping. The repair also involved setting two 1,500-gallon septic tanks and a 300-gallon surge tank (Infiltrator Water Technologies) with a 1 hp Liberty pump sending effluent 480 feet through a 2-inch PVC force main to the pits. Meanwhile, more water leaks occurred, but plumbers couldn’t determine why the pipes were breaking.

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“I had noticed cracks in the clay soil and told the owner I thought something was moving under the house,” says Willis. “He didn’t think so.”

This conversation happened on a Friday. Sunday morning, Willis heard from the owner that the entire hillside had just slid 2 feet out from the back of the house, taking the swimming pool, force main and vent line with it.

On Monday, Willis summoned geologists to analyze the catastrophe. Over two weeks, they determined water had seeped into the home’s sand footing, followed the laterals, and cross-circuited into some French drains below the house. From there, the water worked into the house pad’s keyway and migrated to the seepage pits. The keyway’s cut-and-fill line ran straight across the back of the house.

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“We ran a new force main and left it on the patio while contractors drilled into the side of the slope and anchored it,” says Willis. “Seven months later, I returned to dig a trench, install the line, and connect the system.”

Read more about Bob’s Septic Service in the September issue of Onsite Installer.


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