Structural Repairs Under Way at Costco to Prevent Potential Underground Landslide

There's more than bulk shopping taking place at the warehouse at Cabot and Crown Valley.

Customers wheeling out supersized grocery carts filled with jumbo packages of chips, soda and paper towels have encountered more than the typical long gas lines lately. In fact, there's quite a bit of construction under way that will last through at least year's end.

The construction, which isn't causing significant traffic problems, could continue on and off for several years, according to Mark Maushund, vice president of operations for the Los Angeles region of Costco Wholesale Corp.

"There is an old landslide, about 20 to 30 feet below the surface, that is causing a small amount of movement. The movement is in inches, not feet, but that kind of movement does throw everything off, and last year's rain exaggerated this movement," Maushund said.

According to Maushund, construction crews are installing 52 pylons more than 60 feet into the soil to create an underground reinforcement wall to stop the underground movement.

An employee of Malcolm Drilling Co., the company that is installing the pylons, said that in his opinion, if the repairs weren't made, "the buiding could be lost."

As to what is causing the movement, no one is certain. However, there are suspicions that the 73 toll road is to blame.  

"We surmise that the weight of the traffic on the 73 toll road is having some impact on the situation. You get this kind of movement any time you build on a hillside, but this is more that what it is designed for," Maushund said.

He added that the awareness of the problem and planning to fix it began six months ago.

If this is so, then the California Department of Transportation may be responsible for footing the bill of the repair costs eventually, but for now, Costco is picking up the tab.  Investigations are ongoing, and Costco's Maushund added that Caltrans has been cooperative and helpful during the investigations and repairs.

"Caltrans is sharing the information that they have, and it will probably be years down the road before this gets settled, but we want to emphasize that Caltrans has been great," Maushund said.

Maushund  said the cost of the repairs is in the millions. But he also added that at present there are no alternatives, because there is no way to know for sure what is causing the damage.

He said Costco needs to be proactive and worry about recouping the costs at a later date if—and only if—blame can be attributed. 

He stressed that repairs should cause minimal traffic congestion for customers.

Caltrans could not be reached for comment.