New London — The city’s Department of Public Utilities has come up with a possible solution to the longstanding flooding problem along Bank Street.

Investigation by the department led to the discovery that the water level in the network of drainage pipes on Bank Street is closely linked to the rise and fall of the tides at Shaw’s Cove.

“As the tide rises, so does the level on Bank Street,” said Public Utilities Director Joe Lanzafame. “Under normal conditions it’s not an issue. But when we have high tide, we’re effectively filling the pipes on Bank Street. Its backfilling from the cove onto Bank Street.”

Pumping out some of that water pre-emptively is the plan that Lanzafame said he hopes will solve the problem. A $50,000 automated electronic “jockey pump” is on order and expected to be installed before the end of the year.

Lanzafame recently led tours of the Shaw’s Cove pump station to neighbors and city councilors to help them understand the flooding issue, which has plagued the area for years.

The utilities department, as the result of the creation of a new Stormwater Authority in October, took over operation of the pump station from the Public Works Department last month and has begun not only mapping the city’s entire stormwater system but investigating the causes of flooding in parts of the city.

The work is being led by Lanzafame and employees at Veolia, which is contracted by the city to handle operations and management of the city’s water and wastewater systems.

Several stormwater systems drain into the cove behind the pump station, on city-owned property near the rear of the building that houses Jasmine Thai Restaurant.

A 6-foot discharge pipe moves stormwater from Bank Street and a 206-acre area across the city into the cove. It uses gravity under normal conditions. During rain and a high tide, however, a gate valve at the end of the pipe closes and water is diverted to an underground holding tank under the pump station.

Two large diesel engine-powered pumps switch on and quickly push the water out into the cove.

The pumps are intended to prevent flooding, but since the water level on Bank Street is already high, Lanzafame said, the pumps need time to catch up.

“We’re essentially pumping the tide out,” he said.

The idea is to have the jockey pump automatically move water out of the system in advance of a rain event.

“The goal is to have that process run automatically to keep the pipes drawn down. We believe the system can’t react quickly enough to a microburst or rain event and effectively evacuate the system fast enough,” Lanzafame said.

In the meantime, Veolia employees have been monitoring the pump station before and during rain events.

The tides have likely influenced the water level dating back to the time the pump station was designed by the Army Corps of Engineers and built in the 1970s. It was built to handle a storm surge.

“My guess is that water levels in the pipes was always influenced by the tides, but we’ve never seen this amount of water flow,” he said.

Lanzafame shrugged off, but didn’t rule out, suggestions by some that rising sea levels are the cause of the problem. He said theories that underground pipes from places such as Blinman Street — prone to severe flooding — are improperly sloped have been mostly disproved.

He did say, however, that there appear to be more intense rain events of late. The more likely cause is that the amount of water flowing through the stormwater system has greatly increased through the years as the amount of impervious surfaces — buildings and pavement — has increased.

“The water level on (Bank Street) is relatively high all of the time,” Lanzafame said. “The pumps work, but it’s not working as designed. There’s just more water to move. Water accumulates faster during more intense storms.”

While Bank Street is a priority at the moment, Lanzafame said his department will also be working on a solution to flooding in the Broad Street area and other places across the city.

The Stormwater Authority is funded with a projected $1.2 million in revenues collected this year from a stormwater assessement on property owners, a fee that is based on the amount of their impervious surface area.

g.smith@theday.com