The Los Angeles Department of Building and Safety ordered more seismic testing to determine whether an earthquake fault runs under the site of a proposed 16-story Hollywood development just east of the controversial Millennium Hollywood project.
The call for more seismic testing comes about a week after geology and engineering experts hired by the developer filed a report to the city saying that they found no fault under the property, the former home of KFWB's radio studio at 6230 Yucca St.
The report's conclusions challenge a draft map by the California Geological Survey, which shows the estimated path of the Hollywood fault going through the property.
Luke Zamperini, a building and safety spokesman, said that city geologist Dana Prevost last week asked for additional seismic study.
"Our geologist talked to their geologist and asked them to do more trenching and resubmit," Zamperini said.
The city needs to approve the developer's fault investigation report before issuing construction permits for the project, which would bring 95 residential units and about 14,000 square feet of office space to the southwest corner of Yucca Street and Argyle Avenue.
Group Delta, the geotechnical engineering firm hired by the developer, said earlier this month that it "saw no faults of any kind" during its study. It has agreed to perform the additional seismic investigation requested by the city, which includes digging another trench on the east side of the property.
"Given the amount of scrutiny in this area, the city is erring on the side of great caution and asking for some additional work to reassure that there is no active faulting" on the property, said Michael Reader, Group Delta's chief executive officer.
In light of the report, Reader has asked state officials to remove the fault line from 6230 Yucca St. The state geologist is in the process of reviewing this report and other appeals before it finalizes a map of the Hollywood fault zone later this year.
The state geological survey has said it drew a fault line going through the Yucca apartment site after a study in 2006 reported differences in groundwater levels across the site. One explanation for that unusual occurrence is the presence of an earthquake fault.
The developer's fault report said, however, that the 20-foot groundwater level difference was caused by pools of water collecting on clay buried at different depths.
The report also says that no sharp changes in the soil were found that would suggest an active earthquake fault is under the property.
Work to complete the fault investigation included digging a 100-foot-long trench about 30 feet deep, taking soil samples from eight locations and pushing a sensor into 27 other spots across the property at a depth of 60 feet below the surface.
In the same week that Prevost called for more trenching from the developer, he announced his retirement through a building and safety spokesman.
Prevost, who has been the city's supervising geologist for 15 years, heads the division that is responsible for reviewing and approving geology reports submitted by developers. His division has fallen under scrutiny in recent months for not requiring detailed seismic studies for prominent developments in areas known to be near the Hollywood earthquake fault.
Pascal Challita, a senior geotechnical engineer for the city, will take over Prevost's position beginning Monday, Zamperini said.