LID practices are those applied to minimize runoff at source, where rain falls. Examples include increased pervious cover, disconnection of impervious areas from the storm sewer system, cisterns for collection of roof runoff, grassed swales, green roofs, ponds and bio-retention areas.
SWC Canada Inc. provides inspection, maintenance and repair services for low impact surface intercepting water systems such as:
Detaining runoff in retention ponds can reduce flooding, increase the amount of water that is absorbed into the ground, and allow pollutants to bind to sediments in the ponds or be absorbed by algae and plants instead of traveling to streams and wetlands where they may harm wildlife and human health.
Shallow ditches with gently sloping sides.
Landscape elements designed to concentrate or remove debris and pollution out of surface runoff water. They consist of a swaled drainage course with gently sloped sides (less than 6%), filled with vegetation, compost and/or riprap.
(a.k.a. French drain) a structure including perforated conduits in gravel to expedite transfer of water to or from a soil.
Permeable Pavers / Permeable Concrete
Also known as pervious or porous paving, permeable pavement is a type of hard surfacing that allows rainfall to percolate to an underlying reservoir base where rainfall is either infiltrated to underlying soils or removed by a subsurface drain.
Permeable pavements include:
Unit Pavers - interlocking concrete paving blocks separated by narrow gaps (pores) which are filled with sand and/or gravel.
Grass Pavers - concrete cells or a strong plastic grid system with large pore spaces filled with a growing medium planted with grass or a low growing herb.
Gravel Pavers - similar to grass pavers except that the growing medium and plants are replaced with gravel.
Permeable Asphalt - consisting of an open-graded coarse aggregate, bonded together by asphalt cement, with sufficient interconnected open spaces to make it highly permeable to water.
Permeable Concrete - with little or no fine material in the mix, this concrete has a much larger than usual void space which allows water and air to move quickly through the material to the soils or the base layer below.