What is LID

Low impact development (LID) focuses on ways that we can adapt human-constructed landscapes to manage stormwater and to reduce harmful impacts on natural resources and the environment.

There are many different ways to put LID principles into practice. Examples include:

  • Rain gardens
  • Rain barrels
  • Cisterns
  • Native planting
  • Lawn modification
  • Soakage trench
  • Swales
  • Storm ponds
  • Porous pavement
  • Green Roofs

 

Rain Barrels

Rain barrel diagram showing downspout, diverter, outflow pipe, and spicket A rain barrel is simply a container used to collect water running off the roof. Rain barrels can slow down the flow of water into storm drains by collecting roof runoff and storing it for later use. Using this water for your garden or lawn is also a convenient way to conserve water and lower your water bills.

Fittings designed and sold by Grady Barrels

Fittings designed and sold by Grady Barrels

There are many different ways to design and set up rain barrels, but there are key features that they should include. A rain barrel needs a way to direct water into the barrel. The fittings shown below use a PVC adapter coupling (3″ to 2″) as a funnel to collect water from a downspout. A mesh screen is used to keep bugs and debris out of the barrel. With this system, the water will flow down into the barrel until it is full, at which point it will flow into the overflow pipe.

It is best to place the spigot at the bottom of the barrel in order to make use of all of the collected water. It may be necessary to place the barrel on concrete blocks, or some other sturdy base so that a bucket can fit under the spigot. A hose can attach to the spigot, though the water pressure relies on gravity, so a hose will only work to water downhill from the barrel.

 

 

Cisterns

11,000 gallon cistern at the KCD office.

11,000-gallon cistern at the KCD office.

Cisterns are larger scale versions of rain barrels. Cisterns range in size. While they are more often used on farms or commercial properties, cisterns can also be installed for homes.

Water collected in cisterns can be used for gardens, lawns, crops, livestock, and other activities. Water from cisterns is not suitable for drinking unless a proper multi-stage filtration system is installed. Non-potable water is most often used for irrigation and animals. Cisterns may also be connected to plumbing, but a cross-connection back pressure device is necessary to prevent contamination of public water supply. At our office, water from our cistern is used for the toilets.

Roofing material is an important factor. The best material is powder coated metal, but most new composition roofs are adequate. Avoid collection water from wood roofs and lead flashing.

A 1/16″ screen mesh is a sufficient filter for non-potable water.

KCD may be able to provide financial and technical assistance for cistern installations in unincorporated Kitsap County.


Lawn Amendments

Lawn aerated and topped with half inch of compost

Lawn aerated and topped with half an inch of compost

 

Lawn care can have an enormous impact on the water runoff from a property. The way you take care of your lawn can determine whether your property will increase water pollution or help to reduce it.

Lawn care must be continuing in order to see results. For example, lawn aeration should be repeated annually to maintain effectiveness.

Check out the Common Sense Gardening Guide to Natural Lawn Care produced for Thurston County. Some information is specific to Thurston, but much of the advice is applicable throughout western Washington and beyond.

http://watoxics.org/files/grow-smart-grow-safe

http://sustainability.tufts.edu/wp-content/uploads/EcologicallySoundLawnCare.pdf

Soakage Trench

Soakage trench sketch by City of Portland Environmental Services

Soakage trench sketch by City of Portland Environmental Services

Soakage trenches provide a similar function to rain gardens but are different in appearance. Water is piped into a trench filled with gravel in order to increase infiltration. The gravel trench can be covered with soil so that the area can be used as a lawn or garden.

Soakage trench guide

soakage trench diagram

Click to enlarge this detailed diagram from City of Portland Environmental Services

 

 


Swales

Division O&M 06_27_13 (4) NE Geneva O&M 06_27_13 (2)

Along with rain gardens, soakage trenches, and stormwater ponds, swales are a type of bioretention tool. Bioretention refers to approaches to managing stormwater that use chemical, biological, and physical characteristics of plants and soil components to remove or retain pollutants from runoff water.

Stormwater Ponds

Diagram of a stormwater

Storm water ponds are an example of large scale runoff management solutions. When storm ponds were initially introduced as a means of flood reduction, they were not designed as types of low impact development. Instead, most were built as solely as detention/retention areas. In recent decades, it was realized that these ponds could also function to improve water quality.


 

Permeable Pavement

Fairgrounds road prior to permeable pavement installation

Fairgrounds road prior to permeable pavement installation

Fairgrounds road with permeable pavement

Fairgrounds road with permeable pavement

Permeable pavement is a good way to reduce runoff from driving surfaces. Roads and driveways are usually paved with asphalt or concrete, both of which are traditionally impermeable.

There are a number of permeable alternatives to asphalt and concrete. These allow water to drain through the surface, rather than running off of it.

Stabiligrid parking at KCD office

Stabiligrid parking at KCD office

Green Roofs

Mid-construction green roof on the KCD well house roof

Mid-construction green roof on the KCD well house roof

Green roof on the KCD well house roof

Green roof on the KCD well house roof

Green roofs are a way to reduce the quantity of runoff by retaining water in soil and plants on the roof.

There are a number of important considerations for installing a green roof. A lining is important for preventing any leakage. Also, the roof must be strong enough to manage the added weight from the soil, plants, and water. The plants should be shallow rooted and drought tolerant so that watering is not necessary during dry periods.

Useful resources about green roofs:

Ecoroof Handbook

Ecoroof Project Guide

DIY Ecoroof Quick Guide

 


 

 Choosing between different LID Tools:

Each LID practice has its own combination of practical, economic, and environmental benefits. Likewise, each has different costs involved. There are a number of important considerations, some of which require on-site assessments.

Rain gardens are the most prominent LID feature of our program, simply because of the versatility and broad spectrum of benefits that they offer. Rain gardens are feasible for homes, businesses, schools, factories, and other sites.