Filterra units were installed as part of the sidewalk and streetlight project started under Redevelopment in 2009.
What is a Filterra?
What do they do?
Were the wrong plants used?
Has maintenance ever been done?
Are the missing plants going to be replaced?
Do the plants get watered in the dry season?
According to the brochure:
“Filterra is an engineered high-performance bioretention
system.” What is a bioretention system? Read on.
How does Filterra work? Again, from the brochure:
“Stormwater enters the Filterra through a pipe, curb inlet, or sheet flow and ponds over the pretreatment mulch layer,
capturing heavy sediment and debris. Organics and microorganisms within the mulch trap and degrade metals and
hydrocarbons. The mulch also provides water retention for the system’s vegetation.
2. Stormwater flows through engineered Filterra media which filters fine pollutants and nutrients. Organic material in the
media removes dissolved metals and acts as a food source for root-zone microorganisms. Treated water exits through an
underdrain pipe or infiltrates (if designed accordingly).
3. Rootzone microorganisms digest and transform pollutants into forms easily absorbed by plants.
4. Plant roots absorb stormwater and pollutants that were transformed by microorganisms, regenerating the media’s
pollutant removal capacity. The roots grow, provide a hospitable environment for the rootzone microorganisms and
penetrate the media, maintaining hydraulic conductivity.
5. The plant trunk and foliage utilize nutrients such as Nitrogen and Phosphorus for plant health, sequester heavy metals into
the biomass, and provide evapotranspiration of residual water within the system.”
They filter out contaminants in storm water using plants, soil, and microorganisms. Clear?
Page one of the Storm Water Treatment Plan of the Highway 12 Redevelopment project for sidewalks and streetlights. Dated 9/30/08. The table lists eight Filterra units. This is for the first phase of the project. When the entire project was done, there were twenty-one.
Page two shows the units near Thompson St. the drawing shows two units at the parking lot. Only one was installed.
There were two problems from the start: the trees were not watered, or not watered enough, in the months after they were planted, and they were repeatedly vandalized. Well, three problems actually. Some of the units were installed in sidewalks so narrow that you couldn’t easily push a baby carriage around them or walk two-abreast around them. This is particularly glaring on the west side of the bridge over Pequeno Creek.
From the “Common Issues” section of the brochure:
“the most apparent sign of an issue with a Filterra is dead vegetation. A dead tree will not absorb any pollutants through its roots. If you notice any of these issues occurring in your system, or if you have recently installed a unit that needs maintenance, it’s time to call AQUALIS. Our maintenance and repair teams will ensure that your Filterra units are regularly inspected and operating at peak efficiency,” and
“Typically, using vegetation that naturally grows in the area is the best option, and there are specific plants required by the manufacturer. If you notice that the plant in your system is dying, it may be because the wrong type of vegetation is being used.” What species were used? I know one of the units contains nandina domestica, a decidedly non-native plant that has toxic berries and is considered invasive in some places in the U.S.
Current conditions of the plants in the Filterra units: 12 alive, 5 vandalized but still alive, 4 completely missing.
In 2021 your correspondent had this exchange with Supervisor Gorin’s office about maintenance along the highway.
My original question:
Can you tell me who has responsibility for the areas between the sidewalks and the building along the highway in the Springs? These areas are always full of weeds and look terrible. A Caltrans worker told me the County was responsible per an agreement. At any rate, nobody is paying attention to them. Also those “Filterra” trees need attention. Thanks!, Mike
Below the response from TPW:
…the trees in the filterra bioswales in the sidewalk are the responsibility of the county. Evidently, these trees have been repeatedly destroyed/broken by the public. Anything behind the sidewalk is the responsibility of each property owner. This means that the property owners are responsible for the grass strips noted below. Thanks!
Let us know if we may be of further assistance.
From: Mike Acker <firstname.lastname@example.org>
Sent: Sunday, November 7, 2021 8:59 PM
To: Karina Garcia <Karina.Garcia@sonoma-county.org>
Cc: Arielle Kubu-Jones <Arielle.Kubu-Jones@sonoma-county.org>; Hannah Whitman <Hannah.Whitman@sonoma-county.org>
Subject: Re: Highway 12 jurisdiction
Thanks you Karina,
I’m very impressed that you work on Sunday, but do get some rest!:)
On Nov 7, 2021, at 8:52 PM, Karina Garcia <Karina.Garcia@sonoma-county.org> wrote:
On behalf of Supervisor Gorin thank you reaching out and bringing this matter to our attention. We also thank you for providing a clear description and picture.
Your email was shared with our Caltrans contacts as well as Sonoma County Transportation and Public Works. I am including Arielle Kubu-Jones and Hannah Whitman from our office for follow up, as I will be out of the office for a week starting Tuesday.
My answer: Thanks for your reply Karina. That the areas in question are the responsibility of the property owners does not square with the fact that Caltrans cleaned up a large strip in Agua Client a few months ago. At the time, the worker told me it was really the county’s responsibility, but they were doing it. However, if it really is the responsibility of the property owners, how can the County help inform and coordinate efforts at clean up and beatification? Whoever has the legal responsibility, it’s a community matter that effects us all. We fought long and hard for the sidewalks and street lights and are happy to have them, but these eyesore diminish that positive impact. Below is an example of the cleanup Caltrans did in July. (Image)
Actually, Caltrans was cleaning up the sidewalk of debris that has fallen from the private property along side. But my comment about this being a community matter, no matter who is responsible for what, stands. The County should lead on this, as on many other matters on which they are hands–off.
A Tour of The Filterras