There are plans to install a double faced, externally illuminated 50-foot high billboard just north of the Ballard Bridge on 15th Avenue Northwest, according to Seattle's Department of Planning and Development.

Clear Channel Outdoor Communications, the owner of the billboard, wants to replace an existing sign at 4900 15th Ave. N.W. with a newer one at 4810 15th N.W. The two billboard faces are proposed to be 14-by-48 feet and face northerly and southerly on the east side of the street.

It's not yet determined if the sign is larger than other outdoor billboards on 15th, said Alan Justad, spokesperson for the department of planning and development.

If approved, the billboard would be relocated from 4th Avenue South, where the property is being redeveloped for Sound Transit's Link light rail system.

Representatives from Clear Channel could not be reached for comment.

The new marketing sign would be located in land zoned for high impact industrial uses, such as auto salvage and steel factories, and could require an environmental review. Billboards or commercial buildings in that area must be below 65 feet high, though there is unlimited height limit for industrial uses.

The public comment period for the project ended last Thursday. However, if someone requests an extension in writing, the department would add another two weeks for comments.

"In reality, our planner will continue to accept and consider comments while reviewing the project," said Justad.

To send comments about this project or to ask for an extension of the public comment period, write to Seattle's Department of Planning and Development Public Resource Center, 700 Fifth Ave., Suite 2000 P.O. Box 34019 Seattle 98124-4019, or email prc@seattle.gov. The project number, 3005988, or site address must be included.