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.

Take a moment to read about the project in the Redmond Patch Blog that featured an article 'Rainwater Tour' Gives Residents Ideas for Better Stormwater Management.

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.


What is Permeable Asphalt?

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 Rain Garden?

A rain garden is a plantRain Gardened 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.

Composted SoilWhat 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.

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 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.

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.