The county received the go-ahead Thursday to advertise for requests for proposals and qualifications for the $18.5 million Douglas County Community and Senior Center at Herbig Park.Following approval from county commissioners, Community Services Director Scott Morgan said the advertisement would be released Monday.He told the board at least a half dozen firms capable of handling the design-build concept of the 75,000-square-foot project had expressed interest.Under the design build concept, a single contract is awarded for all design and construction activities. "The design build team emphasizes a maximum, guaranteed price," Morgan said. "Coming in $1 over budget is not acceptable."Morgan said …