The owners of a $3.6 million home at Westport Point have been ordered before the historical commission Monday evening to explain how they will correct what the commission’s chairman and building inspector said is a serious oversight — starting construction on a large retaining wall without his board’s required approval.

In early November, building official Ralph Souza verbally ordered the 2015 Main Road property’s owners, the ANC Nominee Realty Trust, to stop construction on the concrete wall which apparently will house an infinity pool.

The town’s position is that the project, which requires a “certificate of appropriateness” or other certificates from the commission, was not properly vetted, as it lies in the historic district and is visible from a public way — in this case, most visibly from the west branch of the Westport River. The large concrete structure is approximately 51 by 90 feet, and rises about nine feet above finish grade.

“Although the town of Westport building inspector verbally ordered construction to stop ... it appears that construction remains on-going,” commission chairman Rud Lawrence wrote to the trust’s James Sabra on Thursday, Nov. 16.

Though Souza issued a building permit for the construction prior to the work beginning, “neither Mr. Branca nor anyone else on behalf of the ANC Nominee Realty Trust applied for or obtained a certificate from the Commission before commencing construction,” Lawrence wrote.

Lawrence added that the owners need either a certificate of appropriateness, a certificate of non-applicability or a certificate of hardship, and ordered Branca to respond within a week with “a plan to correct this situation.”

He also ordered the trust’s appearance at the commission’s Monday, Dec. 4 meeting, “at which time the commission may determine whether your proposed plan .. is adequate.”

If commission members deem the plan inadequate, he wrote, “the commission may vote to declare the site illegal.” Fines of $300 per day for every day the work continues without a certificate have already been noted to the owners.

The construction has rankled feathers in the point, where neighbors sent up a drone to take aerial photos and videos of the construction project several weeks ago. Neighbors also met informally this Monday to discuss issues prior to next Monday’s meeting, and sent Shorelines a list of talking points they went over.

Among other things, neighbors claim that the “several applications by the owner and his agents to the building commissioner were inaccurate, incomplete and never presented a clear view of the overall project. Communications between the building commissioner and the vice chair of the (commission) failed to recognize the full extent of this project or the potential interest in, and jurisdiction over, it on the part of the” commission.

“This project, in all its manifestations, constitutes a clear challenge to the legitimacy and authority of the Westport Historical Commission and to the Town that it represents.”

Another talking point was that the owner has threatened to sue the commission if the stop work and appearance orders are not rescinded. On Monday, Lawrence confirmed that the threat of litigation is accurate.

Lawrence wrote late Monday that while the power to issue a stop work order does not lie with him, his intent is to start a process that would eventually permit the commission to seek an injunction in Superior Court.