Unexpected asbestos has been found in an elevator shaft at the Lupton City Mill site, officials said.
Bill Payne, city engineer, said the shaft had been covered with debris. When that was removed the shaft that contained friable asbestos was discovered.
It will add $63,296 in city costs for the environmental remediation, plus a $25,000 contingency amount.
The revised cleanup cost is $333,396.
The city stepped in on the cleanup after a private entity tore down part of the old mill, but left some portions standing along with rubble.
The cleanup is by Tradebe Environmental Services.
It is unclear whether the site will be redeveloped or retained as a new city park.