The $3.4 million project came in ahead of schedule and under budget, Claude Smith said Wednesday.
Smith is construction project manager for the county.
He said BurWil Construction, the contractor on the jail project, has finished a "punch list" for the building.
That means items marked as needing work during an earlier walk-through by county officials have all been corrected.
Smith said he was checking over that list Wednesday afternoon and expects he and other county officials will join the contractor and sheriff's staff for a final walk-through next week.
The facility is scheduled to open May 1.
It will cost the county about $1.2 million per year to run the new facility, including about $900,000 in personnel costs.
Ground was broken for the project on April 11, 2006. The county's contract with BurWil called for a "substantial completion" date of April 9, Smith said.
The county received a letter from BurWil marking that point earlier this month, Smith said.
"We've basically been done for two weeks," he said.
The new facility will operate in addition to the current jail. It was built, largely, to ease overcrowding at the current jail - which has beds for 383 inmates but sometimes houses more than 675.
The new building is a stand-alone, self-contained correctional facility.
Bristol-based BurWil Construction submitted the lowest bid on the project - at $3.77 million.
County officials trimmed the scope of the project to get the cost down to $3.44 million.
Smith said he did not have final construction cost figures Wednesday, but the project will come in below that $3.44 million amount.
As described during the bid process, the project includes a new 31,000-square-foot minimum-security facility and an 800-plus-square-foot garage.
The only other option the county had to ease overcrowding was to begin construction of the next phase of expansion of the current jail. That carried an estimated price tag of about $18 million for a 160-bed maximum-security pod, county officials said last year.
No funds were included in this year's budget for the facility's operation.
The county's budget year, called a fiscal year, runs from July 1 of one year until June 30 of the following year. This is fiscal year 2007 because fiscal years are named for the year in which they conclude.
In December, the Sullivan County Commission approved adding about $347,000 to the fiscal year 2007 budget to fund operation of the facility - including payroll for new employees hired March 1, and utilities and other operating costs from May 1 through June 30.
The sheriff's department hired 25 employees to run the new 240-inmate facility.