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Storm water planters are designed in such a way that they can effectively capture runoffs, filter sediments and any pollutant thus preventing them from getting into rivers and streams (Technical Memorandum, 2008).
Types of planters
A planter is either an infiltration planter or a filtration planter; an infiltration planter works by allowing the excess water to seep through the surface into the soil. The excess water on the surface therefore reduces by volume as water gets into the ground; filtration planter, on the other hand, does not reduce the volume of runoff, but works by cleansing the water (Technical Memorandum, 2008).
The filtration planter is lined with material, which does not allow seeping of water into the soil thus preventing unsafe water from getting into the soil. Therefore, the two kinds of planters differ in several aspects including the materials used in designing them and areas where they are located (Technical Memorandum, 2008).
An infiltration planter
The planter helps in reinforcing the natural process of water infiltration into the soil, which is part of the hydrological cycle; water infiltration is important in maintaining the level of underground water, as well as ensuring that excess water on the surface is not a problem to life on the Earth’s surface (Barr Engineering Company, 2001)
How it works
The infiltration planter captures the storm water runoff into a central area; this slows down the movement of the excess water thus ensuring that the runoff has time to seep into the soil. The runoff stands on the planter for some time since it takes time for water to disperse into the different structures of the soil (Barr Engineering Company, 2001). It is therefore important that the infiltration planter is planted in an area with adequate space, and where soil drains well - in areas where the soil does not drain well, a filtration planter is recommended (Eric, 2005).
An ideal area for an infiltration planter is characterized with native vegetation, which is not only functional in the infiltration process, but also contributes to the natural beauty of the area (Barr Engineering Company, 2001). This has made infiltration planters attractive when they are set up in development sites, especially in walkways and in parking lots (Eric, 2005). The measure of performance of an infiltration planter is normally done by considering the relative storage capacity of runoff and the ability to remove pollutants (Technical Memorandum, 2008).
Benefits of an infiltration planter
It reduces the volume as well as the flow rate of runoff on the surface; this has multiple implications including improvement of wildlife habitat and improvement of aesthetic beauty of a landscape (Barr Engineering Company, 2001). The planter does not only work by allowing infiltration of runoff, but it also ensures that the storm water runoff is treated before getting into the soil thus eliminating any pollutant in the runoff (Barr Engineering Company, 2001).
Since the infiltration planters are usually integrated with a landscape design of a development site, it is important to inspect the vegetation in the planter in order to do weeding when necessary (Eric, 2005). The sediments trapped should also be removed regularly in order to ensure the infiltration process is not interfered with.
Infiltration planters can be of different shapes and sizes; in most cases they are made of bricks, concrete, stones, woods or plastic lumber (Barr Engineering Company, 2001). The use of different materials causes the variation in cost of constructing the planter; however, they are often far less cheap than any other storm water management facilities.
A storm water management facility can be considered to be less expensive like the infiltration planter is a swale; a swale conveys storm water at a slower rate and allows controlled infiltration of the storm water as it filters pollutants. Although it is considered to be a traditional method, the facility can help reduce runoff if it is designed properly (Barr Engineering Company, 2001).
The process of treating runoff in infiltration planter is said to be cost effective compared to other plans used in treating runoff, since the ratio of cost to volume of the water is quite lower in infiltration planters (Eric, 2005).