Check out permeable pavement blocks to address urban flooding

At a time when urban India is struggling to deal with flooding after every spell of rainfall, replacing sidewalks with permeable blocks could be an idea whose time has come.
Vehicles make their way through a waterlogged road at ITO as the Yamuna river floods nearby areas, in New Delhi, Friday, July 14, 2023. (PTI)
Vehicles make their way through a waterlogged road at ITO as the Yamuna river floods nearby areas, in New Delhi, Friday, July 14, 2023. (PTI)

At a time when urban India is struggling to deal with flooding after every spell of rainfall, replacing sidewalks with permeable blocks could be an idea whose time has come. Urban planners and environment experts Owen Richards and Martin Cook have developed permeable concrete pavement blocks that can capture, treat and recycle stormwater on pavements and roads. They are to be tried out soon as pilot projects in parts of Delhi. 

Richards is an authority in environmental design, specialising in sustainable water management and climate adaptation. Cook is an innovator in permeable concrete pavements and precast products. They explain to Jitendra Choubey how using permeable concrete is the solution for the urban waterlogging mess. Excerpts:

What are permeable pavement blocks? Will they be suitable for India?
India’s tropical climate and high rainfall make it an ideal location for the implementation of permeable concrete (PC) blocks. These blocks are designed to allow water to infiltrate through their surface and into the underlying layers, reducing surface runoff and promoting groundwater recharge. This is beneficial in areas with high rainfall, as it can help to manage stormwater and reduce the risk of urban flooding, retain moisture within urban environment, maintain healthy soils, vegetation and water system.

How will permeable concrete help avoid urban flooding?
Permeable concrete allows rainwater to infiltrate through its surface and into the underlying soil and groundwater systems rather than running off and overwhelming urban drainage systems. This can significantly reduce the volume of water that needs to be managed by these systems during heavy rainfall events, reducing the risk of flooding.

Please share some success stories related to permeable concrete.
While I don’t have specific examples from climates similar to India at hand, the principles of permeable concrete paving and the associated stormwater management systems have been successfully applied in various climates worldwide with great success.  You immediately capture the rain as it falls by reducing impervious surfaces such as asphalt and concrete and replacing them with permeable concrete paving/pavers. This is called “capturing the stormwater at the source” which is the goal for stormwater engineers and designers. It’s unlike impervious surfaces which direct all stormwater into one drain inlet, creating a build-up, which leads to flooding.

What patented chemicals are used in making permeable concrete? 
Permeable concrete is typically made using standard concrete materials, including cement, water, and coarse aggregate, with the use of some chemical admixtures.  The key difference is that our permeable concrete uses a high content of cement which makes for a very strong pavement slab. However, the mix becomes very sticky and hard to mix and even harder to place. Our patented admixture is a non-toxic additive that enables the mix to have very high water content which helps with product discharge and makes placing so much easier. 

What would a permeable concrete block cost compared to a regular one? When considering the cost, it’s essential to consider long-term benefits. These benefits can offset initial investment. The cost of permeable concrete is minimal compared to damages due to flooding.

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