South Africa’s Water Research Commission published guidelines for Interlocking Concrete Pavement developed by Neil Armitage & Motlatsi Monyake from the Department of Civil Engineering at the University of Cape Town.
Rapid urbanization and increased impervious land surfaces in South Africa have given rise to a pressing issue of heightened stormwater runoff and diminished infiltration. Traditional drainage methods often exacerbate the problem by swiftly channeling runoff to water bodies, leading to erosion, siltation, and water quality deterioration. In response to these challenges, a more sustainable approach known as Sustainable Drainage Systems (SuDS) is gaining traction globally, including in South Africa. Permeable Pavement Systems (PPS), a key component of SuDS, offer a potential remedy by facilitating stormwater infiltration, reducing surface runoff, and improving water quality.
Permeable Interlocking Concrete Pavements (PICP) have emerged as the most widely adopted PPS both internationally and in South Africa since their introduction in 2008. Despite their prevalence, recent infiltration tests conducted between 2017 and 2022 at various South African sites revealed a concerning trend – nearly all tested PICP installations were either clogged or nearing complete blockage, rendering them impermeable. This critical issue underscores the need for comprehensive guidelines to enhance the success and longevity of future PICP installations.
These newly proposed guidelines serve as a dynamic reference document aimed at guiding the design, construction, and maintenance of PICP tailored for South African conditions. Drawing from international standards, such as the American Society of Civil Engineering (ASCE) Standard for Permeable Interlocking Concrete Pavement (ASCE/T&DI/ICPI 68-18), and incorporating insights from the Interlocking Concrete Pavement Institute ® ICPI Tech Spec 18, these guidelines intend to address the challenges identified through years of experience in PICP use in South Africa.
PICP structures consist of concrete pavers with vertical slots filled with ‘gritstone’ (‘joints’), layered on a single-sized stone bedding, basecourse, and subbase. The guidelines also highlight the potential use of geosynthetics and underdrains in areas with low permeability or where infiltrated water poses a threat. This ‘living document’ is expected to evolve over time, incorporating the latest advancements and experiences in PICP utilization in South Africa, ensuring the continued success of permeable pavements in stormwater management.
Read the guidelines here: https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20913%20Vol%202%20final%20web.pdf