EVERETT — As the anniversary of last summer’s torrential rainstorms approaches, the city has unveiled a plan to prevent future flooding in 1,800 homes and businesses that are especially vulnerable.
The city wants to install backwater valves in those buildings, and is offering to pick up most of the cost, while at the same time putting a cap on future insurance claims stemming from flood damage.
A backwater valve, installed on a side sewer line between a house and a sewer main, prevents a backed-up main from flooding into a building’s drains.
A public hearing on the proposed ordinance will be held Wednesday before the City Council votes on the plan during its meeting.
The need for a solution became clear on Aug. 29, 2013, when a violent squall dumped rain on the city at a rate of 2.8 inches per hour. It was the most intense storm recorded in the city since it started keeping records in the 1940s.
Another storm hit Sept. 6, and over the course of those several days, scores of homes and businesses were flooded from backed up stormwater and sewage.
A big part of the problem lies in Everett’s combined sewer-stormwater system, which covers about 6,500 acres of north Everett. Most of the flooding in 2013 took place in areas served by the combined system.
Separating the two systems’ 145 miles of pipe, however, is a gargantuan undertaking the city estimates would take 30 years and cost up to $1 billion.
By contrast, installing backwater valves at the most vulnerable properties is a comparatively quick and cheap project that might prevent significant sewage backups while a more long-term plan for the city sewer and stormwater system is developed.
“It’s one of the few things we can do quickly,” Public Works Director Dave Davis said.
The city estimates that the valve installation would take three years and cost about $4.5 million to do all 1,800 buildings.
Those buildings were identified by mathematically modeling a large “400-year” storm — larger than last year’s storms — and measuring its estimated impact over the entire city sewer system to figure out which buildings would likely experience basement flooding.
The city will also offer a rebate program, in which home or business owners can undertake the work themselves and be reimbursed by the city up to $2,500, the approximate cost of the installation. Part of that will involve disconnecting downspouts that drain into the sewer system and redirecting stormwater runoff onto the property’s lawn.
The rebate program is intended to encourage property owners to undertake the installation themselves and not wait for the city to do the work. Owners of those 1,800 designated properties will receive a notice in the mail.
If a property owner does not install a valve, the city will eventually install one in the public right-of-way on the sewer line leading to that property.
If the rebate program is the carrot to get residents to take the initiative to install the valves, the stick is the cap on settlements.
The city estimates it will pay out about $4.3 million in claims from the 2013 floods. It’s paid out about $2.5 million already, with only larger claims from commercial properties awaiting settlement.
Effective immediately after the ordinance is signed, all claims related to sewer system backups will be capped at $25,000 per structure, or, for tenants, $5,000 per unit to cover personal property losses.
In addition, the city will not settle claims related to those 1,800 properties that do not have an installed backwater valve and disconnected downspout, unless those claims come in prior to the deadline date, the owner wasn’t given a deadline or the backup was caused by the city’s own negligence.
The public works department can extend the deadlines, if needed.
What do about the larger issue of the city’s combined sewer and stormwater system is still being studied.
The combined system was constructed between 1897 and 1963, entirely in the north end of the city. Sewers installed after that period were separated from stormwater pipes.
The city’s Public Works Department is considering a few long-term plans that would separate the two systems, ranging up to the full $1 billion and 30-year complete overhaul.
The least expensive option would cost $283 million and take a decade to complete. All three options would result in higher sewer rates.
The department is expected to make a proposal to the City Council this fall.
A public hearing will be held on the new sewer flooding prevention ordinance during the City Council meeting Wednesday. The meeting starts at 6:30 p.m. in the Council Chambers, located at 3002 Wetmore Ave.