The city is about to raise the downtown flood wall by two feet — a project aimed at preventing the Merrimack River from jumping its banks in a worst-case storm, and also protecting property owners from big hikes in their insurance.
The federal government has ordered the $6 million project, which will allow 35 property owners along the waterway to continue paying for flood insurance at current rates.
But before work on the flood wall can begin, the city must obtain permission from four property owners to access their property for construction. Tonight, City Council will consider agreements with the following: Riverside Place Condominium Realty Development Trust, 70 Washington St.; Alosky Realty Trust, 191 Essex St.; Kifor Development, 151-153 Essex St.; and MBTA for a stretch of railroad track near Little River.
The city would pay $4,000 for the permanent right to access land near the Riverside Place condos parking garage and a $1,000 licensing fee to the MBTA. There is no cost to the city for the other two temporary construction easements, according to paperwork filed with City Council.
In November, the council approved the mayor’s request to borrow up to $6 million for flood wall improvements, depending on whether the city receives any state or federal grants to help with the cost.
Improving the 2,200-foot-long flood wall is critical because federal officials have warned they will decertify the 76-year-old structure if the work isn’t done soon, city officials have said.
In a prior interview, Public Works Director Michael Stankovich said that would increase flood insurance rates for about 35 privately owned properties along the downtown stretch of the waterway by an estimated $250,000 in total per year.
Repairing the flood wall will also allow the city to remain in a program through which the U.S. Army Corps of Engineers would pay to restore the wall if it is damaged in a natural disaster such as a severe flood or an earthquake.
The flood wall is on the north side of the river, essentially between the Comeau and Basiliere bridges, and along Washington and Merrimack streets. It has protected the downtown from being deluged by the Merrimack River since the 1936 flood, which left the business district under several feet of water.
Regulators had set a deadline of last November for repairing and raising the 30-foot-tall wall by two feet, but granted the city an extension prior to the deadline.
The wall begins below the river bed and stretches above the level of the river.
The flood-control project has several parts. It is expected to cost $1.2 million to repair and raise the wall, $2.4 million to renovate and clean the Little River conduit, which runs underground and connects that smaller river to the Merrimack; and $1.4 million to repair the circa 1938 downtown pump station behind the Washington Square Post Office and buy three mobile pump stations.
The city estimated the full cost of modernizing the existing pump station at $3 million, so officials decided to buy the mobile units instead.
Officials have said the mobile pump stations can also be used in other parts of the city in the event of major flooding beyond downtown. The 16-foot-high Little River tunnel is partially blocked with trees and other debris, officials said.
The final $1 million of the project budget is to be set aside for engineering and contingencies, in case unforeseen expenses arise.
The city hopes to borrow the money for the project from the state’s revolving loan fund at 2 percent interest. Annual payments on the loan will be made from the city budget and a small increase in sewer rates, the mayor said.