Planning Commissioners Journal: “Managing Stormwater Runoff: A Green Infrastructure Approach”

This article from the Winter 2009 edition of Planning Commissioners Journal underscores the benefits of working with nature to manage stormwater:

Managing Stormwater Runoff: A Green Infrastructure Approach
by Lynn Richards, Acting Director for the U.S. Environmental Protection Agency’s Development, Community, and Environment Division

…Green infrastructure strategies reduce and manage stormwater through infiltration (water soaking into the ground), capture and reuse (water being stored in a rain barrel or cistern for later use in watering plants or flushing toilets), and evapotranspiration (water being used by trees and plants).

A comprehensive green infrastructure
approach to stormwater management
seeks to:

* Preserve and enhance natural features,
such as undisturbed forests, meadows,
wetlands, regional and neighborhood
greenways, trails, and other natural

* Recycle land by directing new development
to already degraded land, such as
parking lots, vacant buildings, and abandoned

While traditional approaches to
stormwater management have focused at
site-level techniques, green infrastructure
takes into account the wide range of development-related issues at the regional,
neighborhood, and site-level that
affect impervious cover and stormwater

The single
most effective strategy for efficient
land use is redeveloping already degraded
sites such as abandoned shopping
centers or underutilized parking lots
rather than paving greenfield sites.
[emphasis added]

By redeveloping an underused site
that is already paved, the net increase in
runoff from development would likely be
zero – or it might even decrease, depending
on the on-site infiltration practices

In conjunction with the stormwater
benefits just described, a green infrastructure
approach supports an interconnected
network of open spaces and
natural areas (such as forested areas,
greenways, floodplains, and wetlands).
This will improve water quality by
increasing infiltration and groundwater
recharge, while also providing neighborhoods
with access to open space for
recreational purposes…

Landscaping/Tree Preservation provisions
can help reduce runoff by limiting
the amount of impervious surface. Are
large trees preserved during construction?
If not, will they
be replaced?…

Sidebar: Some Environmental Benefits of Green Infrastructure

Heat Impacts Reduced. As paved surfaces
gather solar radiation, the heat is
transferred to runoff, which can significantly
increase the temperature of a creek
or pond and disrupt aquatic ecosystems.
Green infrastructure can reduce these
heat impacts…

Improved Air Quality. Trees and
other forms of vegetation that manage
stormwater runoff can also help to
improve air quality, especially in urban

Sidebar: Making Use of Site Plan Review by Thomas J. DiPietro, Jr.

Stream Buffer. If your town has a stream
buffer ordinance, does that mean your
stream’s water quality is protected? Not necessarily.
Landscaping requirements within
buffers are often needed to ensure that the
buffer provides its intended functions. Existing
vegetation should not be cleared during
construction and the area should not be converted
into lawn. In addition, items can end
up within stream buffers that aren’t shown
on the site plan. Examples include walking
paths, picnic tables, compost bins, and
dumpsters. It is a good idea to specify that
stream buffers are to remain in their natural
condition and that modification and clearing
is prohibited.

The North Street infill project proposed by Kohl Construction would take place in one of the few groves of mature trees left in downtown Northampton. Many large trees would be cut down, with a great deal of disturbance to the buffer zone around Millyard Brook and its surrounding wetlands. Well-intentioned wetlands “improvement” (removal of invasive species) might increase this disturbance even more. Meanwhile, large buildings and paved surfaces on nearby King Street languish either unused or underused.

See also:

Gazette Reports on Kohl Condo Hearings; Pictures of the Latest Proposal; Conservation Staff Report; HYLA Critique
At the Conservation Commission hearing, Land Use and Conservation
Planner Bruce Young mentioned that he finds many properties around
Northampton are out of compliance with wetlands protection agreements.
Enforcement is a tedious process that is consuming a large amount of
his time. People are disregarding no-disturb boundaries, mowing where
they shouldn’t mow, etc. This is entirely consistent with scientific findings
that wetlands buffers of less than 50 feet are generally ineffective at
protecting wetlands. The answer, as one Conservation Commissioner put
it, is “space”…

[Dr. Bryan S. Windmiller of HYLA Ecological Services:] …The shade of a closed-canopy forest produces very different physical
conditions at ground level than experienced in adjacent open areas.  
Open areas are windier and drier at ground level, have sharper
temperature fluctuations, and much deeper frost lines than adjacent
woods.  Rain strikes the ground with greater erosive force in open
areas.  These differences do not end abruptly at the forest edge but
are propagated well into the woods.  Light levels near a forest edge
return to normal (i.e. similar to forest interior) in only a few meters
from the edge (e.g. <20 feet), but wind patterns, turbulence, and
reduced humidity typically extend from 0.5 to several times the average
height of canopy trees (e.g. >>30 feet into the North Street
Woods, Richard T.T. Forman,  Land Mosaics, 1995. Pp. 88-89).  
These altered physical conditions increase the penetration of invasive
plant seeds into the forest, and stress forest interior adapted native
forest floor plants…

People apply numerous toxic substances to their lawns, sheds, and home
exteriors.  Some of these substances are water soluble and readily
transported into adjacent wetlands by runoff or via infiltration into
groundwater and then groundwater discharge into wetlands at low
seasonal water levels.  Other substances are readily adsorbed onto dust
particles.  Dust is to be found in abundance around newly disturbed
house sites and the dust is blown many yards into nearby woodlands on
the altered wind currents near the forest edge.  As a result, wetlands
located in close proximity to residential areas and with little
intervening natural vegetated buffer are prone to elevated levels of
contamination, regardless of the effectiveness of stormwater detention

The intended use of herbicides by the applicant to control Japanese knotweed (Polygonum cuspidatum)
will moreover result in the pollution of the wetland with herbicides
and their toxic surfactant agents.  The commonly used herbicide
glyphosate (Rodeo and Roundup) has been shown to be highly toxic to
amphibians, for example, in numerous papers by Rick Relyea and
colleagues (see summary at:   Japanese knotweed and multiflora rose (Rosa multiflora)
are furthermore difficult to eradicate, even with herbicides.  To do so
will require significant doses of herbicide applied many times.

In the end, such schemes are likely only to result in further degradation of the wetland system…

Smart Growth vs. “Smart Growth”

Smart Growth, in its full flower, contains numerous protections,
safeguards, checks and balances. The Urban Land Institute includes the
following among its Ten Principles for Smart Growth on the Suburban Fringe (PDF):

Identify and Sustain Green Infrastructure
infrastructure networks encompass a wide range of landscape elements,
including natural areas such as wetlands, woodlands, waterways, and
habitat; public and private conservation lands such as nature
preserves, wildlife corridors, greenways, and parks; and public and
private working lands of conservation value such as forests, farms, and
ranches. It also incorporates outdoor recreation and trail networks as
well as cultural and historic resources that provide the community its

When we use the word infrastructure, we usually think
of built infrastructure such as roads, electric power lines, and water
systems and social infrastructure such as schools, hospitals, and
libraries. The concept of green infrastructure, however, elevates air,
land, and water to an equal footing with built infrastructure and
transforms open space from “nice to have” to “must have.” At the same
time, green infrastructure helps provide a framework for growth by
identifying the places that should not be built on, putting a stop to
the project-by-project battles that developers face over open space and
the environment…

The problems with Kohl’s condo proposal include:

* It threatens green infrastructure by putting roads and structures as close as 35 feet or less to a wetland. Scientific evidence
indicates that substantial disturbance within 50 feet puts wetland
ecology at risk and threatens water quality. In addition, the condos
themselves appear to be at risk of flooding

Our Ad in Today’s Gazette: A Review of Our Objections to the Kohl Condo Proposal
True Smart Growth respects green infrastructure, such as trees and wetlands. These greenspaces filter the air, reduce the urban heat island effect, enhance property values and moderate stormwater flows, and they do it inexpensively. Urban greenspace is associated with improved physical and mental health and greater social cohesion in neighborhoods.

More Detail on the Zero Lot Line Proposed Changes; Evaluating Infill Impacts
The maximum possible consequences from the proposed changes need to be
spelled out, including the potential percentage increase in impervious
surface and potential loss of tree canopy, broken out by ward. As with
the new wetlands ordinance,
it’s not enough to evaluate the impacts of new rules project by
project. Long-term impacts at the ward and city level must also be

More generally, the extent of impervious surface,
tree canopy, and other critical metrics should be monitored ward by
ward and reported to the public on an annual basis.

Gazette: “‘Brownfields’ law altering landscape”
Today’s Gazette includes an AP report on the kind of smart growth we
think is great: brownfields revitalization. Reusing buildings and paved
areas, as opposed to knocking down urban trees and encroaching on wetlands, is infilling the right way.

Syd Gernstein: “Brownfields Revitalization Cuts Urban Blight, Suburban Sprawl”
…One obvious benefit of brownfield redevelopment is that it eases the
need for metropolitan expansion. It allows a city to grow by making
better use of the space it already occupies…

MassDEP Brownfields Success Stories

EPA: Brownfields Success Stories