Grass Lawn Park LID Demonstration Project
In November, 2006, the Department of Ecology (Ecology) provided a grant
to fund innovative, low impact development stormwater management
projects. Grass Lawn Park reopened at the end of summer 2008 to reveal
the use of many low impact development techniques. The City is
monitoring the performance of the various LID techniques and reporting
that information to the Department of Ecology.
LID Techniques in the Park
There are several LID techniques in use within Grass Lawn Park where there
are
educational signs posted to describe the benefits of these
various techniques.
Permeable asphalt used in place of traditional impervious paving materials
decreases the total amount of runoff leaving a site, promotes infiltration
of runoff into the ground, reduces the amount of pollutants carried to a
storm drain or waterway, and aids with reducing peak runoff velocity and
volume.
What is a Green Roof?
A green roof is a roofing system that uses vegetation to absorb rain water
and reduce heat reflection.
What is a Rain Garden?
A rain garden is a planted depression that is designed to absorb
rainwater runoff from impervious urban areas like roofs, driveways,
walkways, and compacted lawn areas. This reduces rain runoff by allowing
stormwater to soak into the ground (as opposed to flowing into storm
drains and surface waters which causes erosion, water pollution,
flooding, and diminished groundwater). Rain gardens can cut down on the
amount of pollution reaching creeks and streams. Native plants are
recommended for rain gardens because they generally don't require
fertilizer and are more tolerant of local climate, soil, and water
conditions.
What is Tree Preservation?
Tree preservation, quite simply, is protecting trees from damage or
removal during construction. Tree preservation involves careful
site planning to avoid compaction of soil around tree roots that may
extend well away from the trunk of a tree.
Trees have a great deal of financial value, from increased property
values to various environmental benefits. Trees stabilize the soil and
control water pollution, yield advantageous microclimatic effects which
conserve energy, preserve and foster air quality by removing carbon
dioxide (C02) and airborne pollutants, abate visual and noise pollution,
and provide a natural habitat for wildlife. They also provide welcome
shade to people and add color and interest to the urban landscape. Trees
provide a psychological boost to urbanites. People are generally more
satisfied with their neighborhoods if there are trees. Workers are more
productive and hospital patients recover faster if they can see trees
outside their windows. The benefits of established trees in our
communities are subtle and often overlooked.
What is Compost Amended Soil?
Amending a soil with compost increases the soil's permeability and water
holding capacity, thereby delaying and often reducing the peak
stormwater run-off flow rate, and decreasing irrigation water
requirements. Amending soils will also enhance the lawn's long-term
aesthetics while reducing fertilizer and pesticide requirements.
LID Monitoring
The City is monitoring the performance of the various facilities within the
park.
Monitor the stormwater runoff from the metal pavilion roof and the
green roof on the maintenance building.
Flows are measured to compare runoff rates and will be sampled for
pollutants.
Monitor the stormwater runoff from the basketball courts. One
court uses traditional asphalt while the other uses permeable asphalt.
The City's monitoring program
Quality Assurance Program Plan
is available. Results will be posted as they become available.
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