Wednesday, July 8, 1998 | 11:36 a.m.
Clark County stepped in Tuesday to protect health and safety as the Mandalay Bay hotel-casino settles on its foundation, a Building Division official said.
The county's Building Division will inspect and oversee corrections after the $950 million resort's valet parking garage showed a couple of hairline cracks, Supervisor Ron Lynn said Tuesday.
In the next two weeks the county will allow contractors for Circus Circus Enterprises Inc., developer of the resort, to drill holes up to 250 feet deep to test soils beneath the building, Lynn said.
The combination of shallow ground water found at 30 feet and complex soils is causing the building to settle, he said.
"The health and safety of the building are up to the county," Lynn said. County inspectors will stay on site as the tests are done and contractors solve the sinking problem.
The building is designed for such settling as water is squeezed out of the soils underneath the structure, said Lynn, who also is a geologist.
Driving steel pipes, up to 8 inches wide, into the ground and filling and surrounding them with grout may be a possible solution to the sinking, Lynn said. Each steel cartridge would be tested once in place to make sure it is holding up the building, he said.
Circus Circus executives asked the state Contractors Board today to issue an emergency license to the Pennsylvania firm of Nicholson Construction Co. to reinforce the 43-story resort south of Luxor on the Las Vegas Strip.
UNLV soils expert Neil Opfer said while a rock-solid caliche layer offers an excellent foundation for building in Southern Nevada's desert, the question is what's underneath it.
As Mandalay Bay squeezes water out of the clay layer, the resort will sink, he said. "Is the settlement going to stop or keep going?" Opfer asked. "That's the $64 question."
Most major Strip resorts are built on a steel and concrete foundation called a mat that acts to "float" a building on complex soils, Opfer said. The Mandalay Bay project has settled between 5 inches and 14 inches. In other areas, such as Chicago, buildings typically settle less than an inch.
As Las Vegas Valley residents continue to water lawns, the shallow aquifer, ranging from less than 10 feet to 100 feet beneath the surface, continues to grow and flow from west to east across the valley, making the underlying rock less stable.
The growth of the aquifer could be contributing to the Mandalay's current problem and could affect the valley's future high-rise development.
UNLV geology professor David Weide said Circus Circus is taking the appropriate steps to stop the resort from sagging.
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