Flood control plan gets sunny reception

Three plans to prevent First Street West flooding|

If the residents and neighbors of First Street West were looking for a fight when they went to the community meeting on Fryer Creek flood control last Thursday, they must have been disappointed.

Instead, they were presented with three well-thought out Sonoma County Water Agency plans for reducing flood risk on the block between West Spain Street and the Veterans Hall – plans that, for the most part, kept the water flowing and the parked cars off-limits.

“There are alternatives here that are attractive, that I was not aware of,” said Jim Bohar who, with his wife Christine, attended the Nov. 19 session at the Community Meeting Room. “The group from the Water Agency seemed sincere in looking for a solution which would be acceptable by the public and our neighborhood.”

Three representatives from the county’s Water Agency presented the plans, building upon a $1.9 million grant that’s now on the table for City Watersheds of Sonoma Valley. Kent Gylfe, principal engineer of the project and a Sonoma resident, laid out the background, followed by project manager Greg Guensch’s presentation of the plans themselves. Carlos Diaz ran through the flood modeling, to demonstrate how far each plan would go toward preventing disaster.

Central to all three plans is replacing the “trash rack” at the opening of the underground storm drain responsible for the First West/West Spain streets flooding. The trash rack clogs easily from tree debris, and is difficult to clean, according to Public Works’ director Dan Takasugi. It also doesn’t operate as it is designed to do, he said.

Left undecided was the design of such an improved trash rack that would be crucial in any alternative that leaves above-ground drainage – be it ditch, creek or bioswale.

“If we can put a man on the moon, we can design a trash rack,” said Dick Fogg, a member of the county Planning Commission and Board of Zoning Adjustments.

Key to flood control in all three scenarios would be the construction of underground storage chamber at the Sonoma Valley Veterans Memorial Building west lot, which would divert high water for holding and/or improved groundwater replenishment during wet periods.

A six-acre-foot storage chamber, with minor channel improvements of the open straight-line channel of Fryer Creek at Depot Park, would be effective in preventing flooding in all except a 100-year flood. That was the substance of Alternative 1, which drew a spontaneous, “That’s great! Don’t go any further!,” from a voice among the 20-or so attendees.

Alternative 1 would also be fairly expensive, with an estimated budget of $4.7 million. Finding funds additional to the $1.9 million grant would be crucial.

Both alternatives 2 and 3 called for a smaller three acre-foot underground storage, and other channel improvements including underground piping. Those plans would provide flood protection up to 25-year flooding incidents.

While Alternative 3 would match the “minor channel improvement” model of Alternative 1, and come in cheapest at $3.2 million, many in attendance seemed attracted by the promises of Alternative 2 – the most expensive, at $5.4 million.

Along with the 3-acre-foot underground storage, Alternative 2 also includes a number of improvements to the First Street West section of Fryer Creek, including a pedestrian and bike path along the street, a habitat-friendly bioswale where the current ditch is, and an underground 54-inch pipe to carry heavier flows.

The buried pipe would be used for overflow water volume from the storage area, so the bioswale would have slow-moving, low-volume water most of the year even during high-water periods.

With a controlled low flow through the bioswale, the trash rack at the entry-point to the storm drain would be less of a problem, said the engineers.

“On First Street West, we do have a safety problem,” said Takasugi. When an audience member questioned whether it was a safety problem or a public works problem, Takasugi stood firm. “As somebody who is responsible for the safety of our residents, it’s a concern.”

Safety issues include the current open, steep ditch running along the east side of First Street, a hazard to pedestrians and bicyclists who choose that side of the road for their travel; as well as the dysfunctional trash rack and potential environmental hazard from vulnerable sewage lines crossing the ditch.

Takasugi indicated his receptivity to Alternative 2, despite its price tag. “It would bring many benefits to the city of Sonoma, aside from flood protection.”

The bicycle-pedestrian path would be a definite enhancement to the street, which runs past several tasting rooms and the Depot Hotel Restaurant as well as Depot Park, the Veterans Hall and the Police Station and Community Meeting Room.

Making up an almost $4 million shortfall from city funds might actually be easier, Takasugi suggested, due to Alernative 2’s civic enhancements, including road improvements from a flood-controlled creek.

One couple who lived on the street openly scoffed at the 10-, 25- or 100-year predictions, huffing that “it hasn’t flooded since we lived here.” And another party asked if the coming El Nino winter or the effects of accelerated climate change were factored into the plans.

Carlos Diaz of the Water Agency said the storm modeling was based on NOAA 2014 documentation, the most recent and comprehensive available; but acknowledged that foreseeing the unforeseeable was difficult.

Two items reached unanimous agreement, however: it was a positive development that none of the proposed alternates for Fryer Creek included parking for cars overflowing from the Plaza; and the stand of eucalyptus trees at Depot Park had to go.

Neighbors blame the introduced-species of tree for the considerable debris that can clog the trash rack in as quickly as 20 minutes in a storm.

Though the Water Agency had anticipated public resistance to cutting down the large trees, they were pleasantly surprised how little affection the neighbors had for them. Some even suggested an accelerated schedule for cutting down the trees, with the uncertainty of an El Nino year ahead.

That, however, seems unlikely.

It’s expected the City Council will hear the flood control alternatives, and the city staff recommendation, at its Dec. 7 meeting.

Email Christian at christian.kallen@sonomanews.com.

UPDATED: Please read and follow our commenting policy:
  • This is a family newspaper, please use a kind and respectful tone.
  • No profanity, hate speech or personal attacks. No off-topic remarks.
  • No disinformation about current events.
  • We will remove any comments — or commenters — that do not follow this commenting policy.