The NGL Supply Terminal Co. is evaluating its options for building a liquid propane depot in South Portland after the city’s consultants determined that the facility isn’t allowed under zoning ordinances.

NGL wants to install six 60,000-gallon propane storage tanks at Rigby Yard, an industrial rail site off Main Street (Route 1) between Cash Corner and the Thornton Heights neighborhood. The depot would replace a smaller railside storage facility on Commercial Street in Portland, where the state is expanding the International Marine Terminal.

Woodard & Curran, a Portland engineering firm, determined that South Portland ordinances don’t allow for the transfer of pressurized liquid propane from rail tank cars to stationary storage tanks to tank trucks at that site.

“We look forward to reviewing the Woodard and Curran report and working with the city of South Portland to evaluate all potential options, including ordinance language revisions or design and location alternatives,” said Kevin Fitzgerald, regional operations manager for NGL Energy Partners, in a prepared statement.

Fitzgerald said NGL worked with federal, state and local officials to “carefully select” Rigby Yard for the $3 million propane depot. He said the project is “motivated by and in direct support of the state’s redevelopment of the Portland waterfront.”

Further, Fitzgerald said the depot would be designed “to safely meet the high demand for clean-burning propane at over 50,000 homes and businesses throughout the Greater Portland region.”

Though NGL brought the depot idea to South Portland officials a few months ago, no formal proposal has been submitted.