New Delhi: To conserve rainwater, New Delhi Municipal Council (NDMC) has finalised a plan to construct 139 modular water harvesting pits. Work on the project will start soon.
"Of the 139 pits, 95 will be constructed by the road division and 44 by the building department. Tendering for the project is already done, and work can start anytime on the ground. These pits are environment-friendly, cost-effective, require less maintenance, and take much less time to construct," said NDMC vice-chairman Kuljeet Chahal.
As of now, there are 357 rainwater harvesting pits in NDMC areas. Of these, 273 were constructed by the road division department and 84 by the building department.
"Some of these pits included modular RWH projects, and based on their performance, a decision was taken to replicate the concept. If required, we will take the help of the jal shakti ministry in implementing the project. The points identified will help in evading waterlogging as well as rainwater conservation," said Chahal.
The locations where these pits are proposed include Janpath Road, Ashoka Road, Jaswant Singh Road, Jantar Mantar Road, Hanuman Road Park, Vakil Lane, Balwant Rai Mehta Lane, Copernicus Lane, Bhagwan Das Road, Pandara Park, Subramaniam Bharti Marg, Kaka Nagar and Bapa Nagar.
The modular system consists of pre-fabricated polymer-based blocks that are placed in an interlocked configuration. These are laid around the borewell pipe, which is 30-35 metres deep for efficient percolation of water.
Explaining the operation of the system, an official earlier informed that the modular system consists of three chambers and everything is completely underground, except for the cover of the drain and filter chamber.
"The rainwater collected from stormwater drains on roads goes into underground brick masonry manholes. From the middle of this chamber, a pipe is connected to the second chamber called the filter unit. It has a strainer to catch all dirt, silt and solid items, allowing movement to the steel bucket installed on the lower side of this chamber," explained the official.
The third chamber connects to this bucket arrangement via a pipeline. "The third or main chamber is made of readymade polymer-based blocks and placed in an interlocked position. The whole system is wrapped with geotextile fabric to restrict the entry of soil into the system," said the official.
The structure enables rainwater to seep into the borewell pipe through its perforations whilst maintaining capacity for additional water storage. This design allows the space above to be utilised for purposes such as vehicle parking.
"Further, we have a three-tier system to clean the water before allowing it inside the borewell," the official added.