Two Montgomery County construction projects scheduled for completion this fall--the renovation and expansion of the Olney Library and the new home of the Wheaton Volunteer Rescue Squad-- will likely be delayed because the general contractor is going out of business, an official said Monday.

General Services Director David Dise said Milestone Construction told the county last week it would close at the end of the year. Dise said Milestone, which has performed dependably in the past, had suffered declining performance and complaints from subcontractors about non-payment.

“They started out ahead of schedule. But then the work started to slow down and ground to a snail’s pace,” he said.

Calls to the main number at Milestone’s Sterling, Va. office went unanswered Monday afternoon.

The company’s shuttering will not mean additional cost for the county, Dise said. All firms doing construction work are required to post a performance bond for the full amount of the contract. Dise said the guarantor of the bonds for both projects, Zurich North America Surety, will be responsible for seeing the work to completion.

It will, however mean an “unavoidable” delay in finishing the work, Dise told members of the County Council in an e-mail on Monday.

County officials are scheduled to meet with Milestone Tuesday to discuss the bond for the Olney Library. Milestone’s contract for the fire station is with Wheaton Volunteer Fire and Rescue. Dise said he has not heard definitively what steps it will take.

The $13 million library project, a renovation of the interior and expansion from 16,825 square feet to 22,574 square feet, has been underway since early 2011. Dise estimates that it is about 60 percent complete. Library patrons have been using a temporary kiosk at Longwood Recreation Center.

The $14 million fire station at Georgia Avenue and Arcola Avenue in Wheaton, about 75 percent complete, will replace the current facility on Grandview Ave. The county is splitting the cost with Wheaton Volunteer Fire and Rescue.