Starting Sept. 1, health insurance premiums for employees of the Central school system will increase an average of 4.5 percent overall, but those who pay to cover only themselves will pay less than they do now.

The premium changes were the only change the Central School Board made Monday to its health insurance. Minnesota-based United Healthcare will continue for another year as the provider for the 333 employees in Central who participate in the public school district’s health plan.

The Central School Board also agreed Monday to spend $31,000 to acquire a half-acre-plus stretch of property along Greenwell Springs Road. The property is next to 175 acres the school system is acquiring from the state and is the former home of Greenwell Springs Mental Hospital. The plan is to one day build a new high school on the property.

Superintendent Michael Faulk said the sale of the 0.55 acre is the culmination of months of discussions with the landowner Dustin Pierre.

“This will give us complete frontage along Greenwell Springs Road,” explained Faulk.

He said a new high school is at least five to eight years away, and the school system should get the deed for the 175 acres from the state later this week.

The changes in health insurance premiums approved Monday could have been far higher.

Kerry Drake, employee benefits consultant for the school system, said United Healthcare initially proposed a 12 percent increase. But when the school system requested proposals from other health care networks, United Healthcare lowered its offer to 7 percent. While Aetna and Humana’s proposals offered even less, they called for changes in benefit structures for employees, while sticking with United Healthcare meant continuity, Drake said.

In moving to United Healthcare a year ago, the school system made some cost-saving changes to its coverage, including applying a surcharge to those who could get coverage from their spouse’s employer. About 40 people ended up dropping Central’s plan as a result.

The overall savings came to $215,000. Some those savings were used to offset premiums for everyone, amounting to $54 per employee across the board.

The biggest winner were employees who cover only themselves, all of whom will see a premium decrease. Those on the school system’s “High Deductible” plan will pay $75.42 per month in 2016-17, a decrease of $20.28. Families on the “$1,000 Deductible” plan will have the biggest hike, $57.35, bringing their monthly premium to $978.04 a month.

“I think we accomplished quite a lot in the environment we’re in,” Drake said.