Port of South Whidbey commissioners have agreed to spend more than $150,000 on a small parking lot at the bottom of Wharf Street in Langley.

The board met Tuesday and OK’d a seller’s counter-offer of $140,000 for the property. The port has been negotiating back-and-forth with the property owner, Wharf Street Holding Company, LLC, for months. The settled amount was agreed upon after the port’s last offer of $130,000 in late August was rejected.

The deal, which is set to close on Sept. 30, remains contingent on the results of a detailed environmental review. The port already hired a firm to do a preliminary study, but it determined the site is located next to a former “Chevron bulk plant” and that additional review was necessary, according to Jan-Marc Jouas, interim executive director the port.

Port commissioners agreed to the extra expense to ensure it won’t buy a property with hidden problems, such as fuel-soaked soil or old tanks that need to be removed. Given its past, the risk is just too high to gamble.

“It’s anybody’s guess to what they will find,” Jouas said.

If a problem is discovered, the port has the option of backing out of the sales agreement.

The estimated expense of both environmental studies is about $11,000. That combines with the cost of an estimated $1,000 property valuation, which determined the fair market value at between $100,000 to $120,000.

The initial sales agreement between the port and Wharf Street Holding Company was for $170,000.

If the second environmental review comes back clean, Jouas estimated the total price tag for the lot at about $155,000; that includes closing costs.

Once the deal is complete, he said the port will use it as a parking lot for the marina. The commissioners have yet to discuss any immediate improvements.

“That’s for another day,” Jouas said.