DRAPER — Although the Utah Geological Survey did not detail landslide areas in Draper's SunCrest development, the lead geological manager told concerned residents and city officials Tuesday night that ancient landslide areas still have a risk of moving.

On top of that, it should not be assumed that man-made alterations — like grading and lawn watering — have no effect on stability.

Earlier this month, developers for the 3,900-acre SunCrest disputed a city-commissioned study on the future landslide risk of the south mountain community. SunCrest had submitted its own geological findings to Draper and, following protocol, the city then hired outside consultants to review the SunCrest study.

According to that report, obtained by the Deseret Morning News, the planned community with million-dollar views of the Salt Lake Valley is built on ancient landslide areas on Traverse Ridge.

Oregon-based Landslide Technology created the report and listed several options Draper should follow to avoid landslide risks, like implementing an emergency response fund, posting landslide warning disclosures and obtaining insurance for all residences.

SunCrest developers took issue with the report and threatened to sue the city for $500 million if officials made it public. They have since dropped the threat.

"We were concerned that the city might be giving too much reliance to a study that was very, very preliminary," SunCrest attorney Bruce Baird said, adding SunCrest has spent seven years and $2.5 million doing geological surveys of the south-valley mountain top. "We have tested it thoroughly. There's probably no more tested mountain in Utah or in the western United States than this mountain."

Added SunCrest general manager Ed Grampp: "Our primary concern is safety."

SunCrest has made $130 million in sales on the site, which currently has 720 homes and a potential for up to 3,800 units. Home prices range from $220,000 to $2 million.

The Utah Geological Survey was brought in for Tuesday's council meeting as an unbiased party to present its "lessons learned" from recent landslides in other Utah developments.

"It's not that often that you get new landslides. Most landslides are reactivation of existing landslides," UGS geological manager Gary Christensen said. "It's rare to find stable 'old' landslides."

The mayor and council members expressed concern over the potential risk, especially since "warning signs" have been evident in the 7-year-old development. In June 2005, part of a hill eroded after a road was put in next to the slope, putting the edge of the hill a few feet from a resident's back yard.