HARPSWELL — Potential soil contamination could thwart the town’s planned purchase of waterfront property.

The Board of Selectmen on Tuesday approved an amendment to an agreement for the purchase of nearly 6,000-square-feet of land abutting the Lookout Point town landing on Harpswell Neck.

Voters approved the $85,000 purchase in a November referendum.

The amendment calls for a $7,000 environmental assessment of the land, after an initial report from Portland-based Ransom Consulting determined the soil could be contaminated.

Under the amendment, the town will split study costs with the land’s current owner, Dain Allen, a fisherman and proprietor of Allen’s Seafood, if the purchase is consummated.

Chairwoman Elinor Multer said the town must close on the sale no later than Dec. 30, or risk losing the land.

The results of the new study could determine whether selectmen decide to continue with the purchase.

“I suppose that would depend on the size of the problem and what mitigation would be involved,” Multer said. “We will have a lot of discussion over that. We have no preconceived notion on what we would do.”

If results are not satisfactory, selectmen can either terminate the contract, or purchase a portion of the land that meets the contract’s terms and conditions.

Ransom’s assessment, based on correspondence with Allen and an environmental database search, found that the soil in Allen’s waterfront property could be contaminated with oil and/or hazardous materials.

The source of contamination could have been soil transferred from land near leaking fuel tanks at Allen’s Seafood, use of the land for boat storage and maintenance operations, and historic shipyard activities that date back to 1800.

The report said findings from the follow-up investigation should be used to evaluate potential health and environmental risks associated with redevelopment of the property for a proposed expansion of Harpswell town landing.

Those findings will be used to “identify whether remediation or mitigation measures are necessary to eliminate these potential health and environmental risks,” the report said.

Selectmen originally sought the land after Allen offered it for $7,000 less than its assessed value of $92,000. The purchase is expected to help the town protect public waterfront access.

Dylan Martin can be reached at 781-3661 ext. 100 or dmartin@theforecaster.net. Follow him on Twitter: @DylanLJMartin.