A rain garden or a bioretention cell is a depressed area containing a backfill that is porous under a vegetated surface. Often, these areas have an underdrain to encourage infiltration as well as filtration, especially in soils that are clayey. Bioretention cells provide pollutant removal, groundwater recharge, and runoff detention. They are an effective solution in urban areas or parking lots, where green space is limited.
-Gutter and curb elimination
Gutters and curbs transport flow really fast to a stormwater drain without allowing for pollutant removal or infiltration using an inlet filter. Eliminating gutters and curbs can reduce runoff volumes and increase sheet flow. Maintaining sheet flow by removing gutters and curbs that direct runoff into bioretention basins and swales that are vegetated helps to prevent soil erosion by stormwater also helps retain hydraulic conditions (pre-development). A level spreader, which is a channel designed to transform concentrated runoff into sheet flow and distribute it uniformly across a slope, may also be included in order to prevent soil erosion.Stormwater and Watershed Management
They are shallow outlets covered with grass that help to slow down runoff while facilitating infiltration. The sustainability of grassed swales depends on soil type, land use, imperviousness of the watershed that is contributing, and the slopes and the dimensions system of grassed swale. Grassed swales can be used to manage runoff from the drainage areas that are less than four hectares in size. It is encouraged that you use natural areas that are low-lying and drainage courses that are natural should be utilized.
-Green parking design
These, when applied together, reduce the contribution of the parking lots to total cover that is impervious. Green parking lot design techniques include minimizing the dimensions of parking lot spaces, setting a maximum number for parking lots of spaces, utilizing alternative pavers in overcrowded parking areas, making use of bioretention areas to treat stormwater and incentives for structured parking.
They are rock-filled trenches without any channels. These trenches collect runoff when there is a storm and release it into the soil through infiltration. These trenches maybe used in conjunction with the other devices meant for infiltration of storm water using an inlet filter. This will provide peak flow attenuation as well as the quality control of water. Runoff that contains high levels of hydrocarbons or sediments that may clog the outlets may need to be pre-treated using other techniques such as water quality inlets.
-Inlet protection devices
These are also known as hydrodynamic separators and are flow-through structures with a separation or a settling unit to remove oil, trash, grease, etc. You can use this technology for the pre-treatment of the other inlet protection devices. They are commonly used in the potential stormwater areas, where there is a high concentration of pollutants.
They promote the recharge of groundwater. Some pavements are used to create voids on the corners of the pavers. Concrete grid paver systems are made of concrete blocks, which are used to create voids inside the blocks, by clearing the finer particles inside them.