New Haven has not updated its sewage and drainage system for over 130 years. Now, the Elm City must move forward with a $14 million project to update those essential systems, officials said at Wednesday’s City Plan Commission meeting, because once the two new residential colleges are under construction it will be prohibitively difficult for the city to do extensive work on the systems.

At the meeting the commission approved the Greater New Haven Water Pollution Control Authority’s request to convert the city’s antiquated sewage and drainage systems into one that will carry solid waste and storm water in separate pipes, said Mario Ricozzi, manager of design for the water pollution authority. He said the city’s current system carries both forms of waste in the same pipes.

Asked why New Haven has not updated its sanitation network for approximately 130 years, commission chairman Ed Mattison said that it came down to one issue: “money.”

“It’s extremely expensive to replace sewers,” he said, adding that the current initiative would not be possible without a state grant that covers 55 percent of the project’s total cost.

“Ideally, things would have been updated 20 to 30 years ago” said Ward 9 Alderman Rolan Lemar.

But the city has run into two major problems as it tries to renovate the system: Installing over 1,200 feet of pipes beneath the city will increase congestion because large portions of city roads will need to be dug up and construction workers may have to uproot a number of New Haven’s landmark trees, city officials said.

According to the water pollution authority’s proposal, traffic problems could be minimized by digging trenches on the sides of intersections, which is more expensive but quicker and less disruptive than digging up roadways.

Two city engineers said they hope to use this method both to save many of the landmark trees that would otherwise have to be uprooted because of the renovation.

“Completing the project with minimal harm done to our trees completes something environmentally positive for New Haven” said the city engineer, Richard Miller.

The water pollution authority has enlisted the help of a New Haven-based organization known as “Care of Trees” to help it preserve the landmark trees during the installation of the new sewage network. The organization has provided arborists to consult on the project and assure the protection of the trees.

The future of one tree is of particular concern to city residents, Ricozzi said. It is a large sycamore located at the intersection of Orange and Trumbull streets, where drivers exit Interstate-91 and enter New Haven. If that tree is cut down, officials said, residents would be outraged.

“We all anticipate being able to save it,” Lemar said. “But if it presents a big enough problem we will be sure to go through the public channels to remove it.”

The new network will stretch from Canal Street to Orange Street and will consist of about 10,000 feet of pipeline.