Mayor Nickels backs Arboretum plan to fix Madison Valley flooding

Seattle Mayor Greg Nickels is recommending the city spend up to $33 million on a drainage project in flood-prone Madison Valley that would divert stormwater overflows to a new storage tank in Washington Park Arboretum.

The long-awaited recommendation now goes to the City Council, which could vote on it as early as the end of May.

The proposed fix is aimed at adding capacity to a drainage system that repeatedly maxes out during heavy storms, leading to sewage backups in homes and flooding on local streets. One such storm, in December 2006, claimed the life of Madison Valley resident Kate Fleming, who drowned in her basement.

Nickels' announcement was welcomed by Madison Valley residents who opposed a cheaper option that entailed bulldozing 17 homes in the 200 block of 30th Avenue East and replacing them with a 2-million-gallon storage tank underground.

"I am so greatly relieved," said Barbara Lynn, president of the Madison Valley Victims Association, a neighborhood group formed after the 2004 flood. "I was so frightened I would lose my neighbors."

The 2-million-gallon storage facility south of the playfield in the Arboretum would divert stormwater away from 30th Avenue East and East John Street, the most flood-prone point in the Madison Valley basin, according to Seattle Public Utilities (SPU).

SPU officials say the project also would reduce flooding in the so-called "Madison Sag," a low-lying span of East Madison Street where runoff during the December 2006 storm overwhelmed the drainage system and overflowed onto adjacent streets and properties. The pond grew and grew until a private retaining wall gave way, sending a river of muddy water downhill and into Fleming's basement.

"This proposal will greatly reduce the decades-long risk of flooding in the Madison Valley," Nickels said in a statement. "This alternative combines sound science with intensive neighborhood outreach to create a solution that is good for the residents and the city."

In addition to building the storage tank in the Arboretum, the project includes expanding an existing drainage facility in the 100 block of 30th Avenue East. The city bought two homes there last year and demolished them.

The expanded capacity should greatly reduce major flooding and sewage backups in the Madison Valley, officials say, based on computer- and physical-modeling studies for which the city has paid some $750,000 since 2005.

Nickels' favored proposal likely will be discussed by a City Council committee as early as May 13, followed by a public hearing the next day at 6 p.m. in Council Chambers.

Lynn urged the council to pass the proposal. City officials "are taking responsibility for a problem they created," she said. "It's been a long, scary period of time."

Sanjay Bhatt: 206-464-3103 or sbhatt@seattletimes.com