Hawaiian Electric Co. is seeking a permit from the Honolulu City Council for an estimated $1.6 million in improvements at the Kahe Power Plant in Nanakuli. The permit would allow construction of a new 40,000- to 50,000-gallon demineralized water-storage tank to replace an older tank that would be converted to reverse osmosis water storage.

It would also permit the replacement of other water-storage tanks on the property.

The new tank and replacement tanks are necessary to operate the facility safely and efficiently, HECO officials said.