City Council members were told on Tuesday that the cost has soared for moving a sewer line completely off the Harriet Tubman industrial site.
Bill Payne, city engineer, said it initially was around $1.5 million, but is now pegged at over $4 million.
Councilman Chris Anderson, who heads the council's economic development committee, said the assertion brought "stunned looks" to faces of the council members.
That route would be along Roanoke Avenue to Olive Street.
Mr. Payne said a less-expensive route would have it go along the edge of the property by the railroad track where a light rail service has been proposed. He said it would encumber a portion of land by the track. That would be about $1.5 million.
The city is applying for a state grant of up to $500,000 and would have to provide matching funds.
Charles Wood of the Chamber of Commerce said some 45 communities are applying for a limited number of grants. He said there would be 12 grants if they are $500,000 each. Or, he said, some might be as small as $50,000.
Mr. Wood said the Tubman site is currently the largest industrial site in the county.
However, he said there are "challenges" to landing an industrial prospect because it is in a blighted section of town. "Anyone driving around can see it is a neighborhood in need of renewal," he said.
The city paid $2.6 million for the housing development in East Chattanooga in early 2014. The buildings at the site were razed.
The 24-inch sewer line bi-sects the property. It is planned to replace it with a 30-inch pipe.
Councilman Larry Grohn questioned whether there is adequate access to the site, noting there is a bottleneck at the Wilcox Tunnel. Mr. Wood said the aim is to tie it into Amnicola Highway.
Chairman Moses Freeman said proceeding with the project is "a no brainer." He said the site, plus the adjacent planned railroad service, could help transform that section.