A Hole or Sunken Spot Opened Up in My Yard (Olalla, WA)

What usually causes sinkhole or sunken spot in Olalla

In Olalla we check poorly compacted backfill from an earlier dig before anything else, because a well pump that runs all night is how it shows up here. A trench that was dumped full and never compacted settles for years. Bluff clay on Colvos Passage makes the signs misleading, so we confirm rather than assume.

Next: a leaking water service line washing out the trench. The most common cause on a sunken trench line. With hardpan on Banner Road under pasture parcels off Olalla Valley Road, the symptoms can look identical to the first cause, which is why the meter test and the locate matter.

And a collapsed or separated drain line: old clay tile or crushed corrugated pipe lets water wash soil into the pipe and away. Less common on wooded acreage on Banner Road, but we've found it near the Olalla Bridge.

First steps on a Olalla property

Olalla has almost no utility meters, so the locate starts at the well's pressure tank and the first job is proving the loss is in the buried line and not at the pump, check valve or tank.

Do this before anyone digs peat in the Olalla Creek valley in Olalla: keep everyone off it and mark it. Don't fill it until the cause is known. It takes minutes and it tells us whether the problem is on wooded acreage on Banner Road or inside the house.

How we fix it

The repair side is underground water leak detection. On waterfront on Colvos Passage that means trace the line, then repair, if you want us to in outwash that drains and hides leaks where the problem actually is, then correlate. If what we expose is galvanized on Colvos Passage cabins at the end of its life, we say so with the pipe in your hand.

From the Olalla Bridge to Al's Grocery and out around Olalla Bay, sinkhole or sunken spot is a regular Olalla call for us. About forty minutes down Highway 16, and emergencies on pasture parcels off Olalla Valley Road dispatch immediately, any hour.