Permeable Curbs for Storm Water Pollution

One of the problems that increased urbanization poses is storm water pollution. Several control measures exist that are used to treat and reduce pollution in our waterways, one of those being permeable concretes; but these have not been widely adopted.  The goal of this project was to develop a permeable curb apparatus that could be used in retrofitting conventional streets. The permeable curb is comprised of a permeable concrete mix with a perforated pipe running through its center, this allows for water to filter through the porous concrete and continue downstream through the perforated pipe which would eventually lead to our water ways. Project goals include determining permeable curbs pollutant removal efficiencies, and best cleaning options needed to be optimally utilized in urban environments. A test apparatus simulating a typical street profile is used in the laboratory environment to determine the percentage of solids that can be removed from the water treated for typical design rain events, the potential for clogging and fouling of the curb, and the ability to recover lost performance through cleaning the permeable curb. Results to date show that 95% solids removal is possible for up to 15 years of simulated solids loading to the curb. The diameter size range of the 5% of solids that do pass through the curb were measured to be in the range of 2 - 55 mm. Particle sizes larger than this tend to be caught within the curb and contributed eventually to curb clogging resulting in reduced hydraulic flow capacity.  Cleaning cycles of the curb at a moderate backwash rate of 0.1 m3 m-2­ min-1 did not recover solids trapped within the curb with only 7 % of the prior trapped solids removed from the curb in the cleaning process.