Property owners who illegally demolish or alter historic buildings in Pleasanton could face substantial monetary fines and see long-term development restrictions imposed on their land under changes to the city’s historic preservation ordinance.

The Pleasanton City Council at its Dec. 17 meeting unanimously approved additions to its historic preservation law that would allow the city to impose fines and development restrictions when buildings identified as historic are destroyed or altered without city approval. The new rules are set to take effect Jan. 17.

While historic preservation rules regulating changes to historic buildings have been in place for years, Councilwoman Kathy Narum said, the new rule is the first attempt to discourage and penalize unpermitted historic building demolition and alteration. “We missed putting teeth into enforcing it,” Narum said.

Among the changes approved by the City Council is a limit on future development on land where a historic building is illegally destroyed or altered. When the owner of a historic building demolishes all or part of a historic building, the new ordinance will trigger for 20 years a restriction on the construction of a replacement building on the same land that is larger or substantially different than the one illegally destroyed or altered.

Ellen Clark, Pleasanton’s director of Community Development, said that when shaping the ordinance, the city’s staff looked at what is being done in other California cities, keeping in mind property owners should have a reasonable ability to make alterations to buildings. But there also should be penalties in place for illegal demolition or alterations, she added.

While the ordinance does not set specific fines for illegal demolitions or alterations, it authorizes the Director of Community Development to set fines. Fines could amount to the equivalent of the appraised value of the building prior to the violation, or the replacement value of the demolished building, whichever is greater. Any fines imposed under the ordinance are appealable to the Planning Commission and City Council.

In a related matter, the City Council approved changes to its purchasing procedures manual that will allow it to cancel contracts with companies that violate any city, state or federal law.

The issue came up in October when City Council members Karen Brown and Julie Testa sought to block a contract amendment for on-call building maintenance and repair work from a Pleasanton general contractor. The idea was to penalize the company for participating in the illegal demolition of a historic single-story house at 4371 Second St. over the summer. But there was no legal mechanism to terminate the contract. They were unable to secure enough votes. The contractor ultimately gave up the contract, worth up to $400,000, for unrelated issues.