Eroded Well Suspected in Riding Center Fall : Accident: Casing may have collapsed, DWP officials say, leading to woman’s 20-foot tumble into sinkhole.

A day after a woman fell 20 feet down a sinkhole next to an inactive well at the Los Angeles Equestrian Center, Department of Water and Power officials on Sunday speculated that the cave-in may have been caused by a deteriorated steel lining.

“What can happen in a well is the casing rusts out, corrodes out,” said Laurent McReynolds, a DWP operations manager. “The casing will get a break in it and dirt will fall into the well and water carrying dirt into the well could create a sinkhole. That’s one possibility.”

McReynolds said the only way to tell if a well is damaged is to lower a camera into the shaft to inspect the integrity of the lining. Officials from the city of Burbank and DWP planned to call in a geologist to inspect the well today, hoping to determine exactly how the sinkhole formed.

Carol Wood was pulled unhurt from a 20-foot sinkhole Saturday, about an hour after she fell in near a bridle trail. Wood stood on a concrete slab near the wellhead to let some horses pass. When she stepped off the slab, a two-foot-wide crevasse opened and pitched her into an underground cavern.

Active wells are inspected regularly, but inactive wells, like the one near the Equestrian Center sinkhole, are not on an inspection schedule. Officials were not able to determine Sunday when this well, which has been idle since the mid-1980s, was last inspected.

On Sunday afternoon, a DWP crew stood watch over the cordoned-off area near the well.

The well itself is about one foot in diameter and reaches 200 to 300 feet underground. Water from this well--as well as from five others in the Equestrian Center area--was pumped to the Silver Lake Reservoir until they were discovered to be contaminated.

More than 100 wells are operated by the DWP within city limits. As many as 30 of those wells are inactive and therefore unlikely to be inspected regularly, McReynolds said. McReynolds, speaking from his home, said there were “hundreds” of wells in the unincorporated areas of the county, but could not give a specific number.

Friends said Wood was badly shaken after the fall. She was taken to St. Joseph Medical Center in Burbank and was released by Sunday morning.

Employees of the Bar-S Stables in Glendale, only a few blocks from the well, said the bridle trail where the sinkhole formed is frequently used by riders. The two-foot hole could easily accommodate a horse’s leg, and a stable hand who saw Wood just after her fall said the weight of a horse and rider could have broken through the thin crust that separated the sinkhole from the surface.