Washington state’s Pollution Control Hearings Board last week
decided that big cities and counties are different from small ones
when it comes to stormwater management.
That’s not exactly what environmental groups wanted to hear.
They make a good argument that stormwater is stormwater, no matter
where it comes from, and it needs to be cleaned up.
But, as I described in a story in
story last Tuesday, the hearings board recognized that big
cities and counties have more resources to develop and enforce
sophisticated stormwater programs, including requirements for
low-impact development wherever feasible.
The decision that LID would not be mandated for smaller entities
came as a relief to officials in Kitsap County and dozens of cities
across the state struggling to implement the Washington Department
of Ecology’s 2005 stormwater manual (or its equivalent). Once that
goes into effect, developers may actually choose to use LID to keep
their costs down, according to experts.
Art Castle of the Home Builders Association of Kitsap County has
long argued that LID should be encouraged but not mandated, because
it does not work for all sites. Castle, who is leading the charge
to write LID guidelines for Kitsap developers, anticipates that it
will be the method of choice if the rules provide adequate “flow
credits” for systems such as rain gardens. Without adequate flow
credits, developers could be forced to install both low-impact
systems AND traditional stormwater ponds.
It’s all a matter of engineering, and there remains some
disagreement about how much water such systems can handle. That’s
why studies are under way in several jurisdictions.
According to the Pollution Control Hearings Board, Ecology made
a mistake in not requiring cities and counties to move deliberately
toward adopting standards to reduce or eliminate surface water
runoff.
In a decision issued in September, the board decided that the
largest cities and counties need to require low-impact methods
whenever site conditions allow.
In last week’s decision, the board said smaller jurisdictions
need to “identify barriers to implementation” of low-impact
development and to set up a time schedule to take actions to remove
those barriers.
The latest decision affects Kitsap, Thurston, Skagit, Whatcom
and Cowlitz counties along with 80 cities ranging from 3,000 people
to more than 100,000 — including Bremerton, Bainbridge Island,
Poulsbo and Port Orchard.
Download
the full decision (PDF 296 kb) from the hearing board’s Web
site.
Read what the
environmental appellants had to say following the ruling.
Going back to the Kitsap Home Builders for a moment, the LID
guidelines have been submitted to the Washington Department of
Ecology in draft form. Once approved (and Castle says some
amendments are needed), this document could save developers lots of
money by helping them move their LID projects through regulatory
authorities with the least hassle.
The document, called “LID
Guidance for Kitsap” (PDF 8.2 mb) is not just a helpful design
manual for engineers, but it provides the most complete description
of LID that I have seen. Read just the overviews, or dig as deeply
as you want into the technical aspects of LID. Other information
can be found on the Home Builders Web
site.
Here’s the description of integrated LID design, which
encourages developers to look at the natural landscape before
laying out their plans.
Integrated LID design looks at stormwater as an important asset
in a functioning watershed. Design goals include preserving natural
flows over and through the site as much as possible. Design
strategies include preserving natural drainage patterns and
minimizing impervious surface to reduce runoff, which in turn
facilitates detention, infiltration and evapotranspiration via a
healthy soil and vegetation system. All components of the system
are designed to complement one another.
By comparison, conventional design tends to be more linear and
disintegrated. Site layout is driven primarily by tradition and
convenience; sites are cleared, graded and paved. Stormwater is
treated as a hazard to be removed from the site as quickly as
possible via hard conveyances. Resulting flow rates and volumes are
delivered to large central detention facilities to capture and
store the water until it can be released back into the system
downstream of the site. Components of the system are designed to
manage the problem caused by the next component upstream.
Since I’m mentioning information sources, I should point out
that Puget Sound
Partnership continues to expand its information about LID.
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