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NDMC develops modular rainwater harvesting pits to conserve water

by IP Staff

NEW DELHI: Aiming to conserve water resources, protect the environment, and to provide an independent water source in areas,  New Delhi Municipal Council (NDMC) is developing Modular Rainwater Harvesting Pits in its area, it is informed by Shri Satish Upadhyay, Vice Chairman –NDMC.

After developing various “Conventional Rainwater Harvesting Pits” in its area. Now, NDMC is developing “Modular Rainwater Harvesting Pits”. Shri Upadhyay said that these pits are not only cost-effective but also take a shorter time to install and require less maintenance. He said NDMC’s Road Division had already developed 160 modular pits and now working on 95 such more pits at different locations in the NDMC area, the work order is to be awarded by this month and the project is to be completed by March 2023.

He added the benefits as – The Rainwater in its pure form is captured and added to the natural ground water table through a bore-well, the Water table will be increased, Balance of water can be restored in the reservoir for use of irrigation in lawns and other places, etc. if required, Optimum space utilization restoring surface to as it was, Rain Water Harvesting chamber using the modular technology are accidentally free & economic too, Less time of construction is required, No dust pollution in the atmosphere during construction as no stone dust coarse sand/aggregate is required for construction as readymade polymer-based blocks are brought at the site and placed in interlocked position.

While briefing the details on how it works, Shri Upadhyay said that the modular system consisted of three chambers wherein the rainwater collected from storm water drains enters the underground brick masonry manholes, which are around 1.2-metre wide and 1.2-meter deep. From the middle of a chamber here, a pipe goes to the second chamber called the filter unit, which is around 2-meter deep. It has a strainer to catch dirt, silt, and other solids allowing movement of the steel bucket installed on the lower side of this chamber. The bucket has a pipe going to the third and main chamber. The main chamber is made of pre-fabricated polymer-based blocks that are placed in an interlocked configuration. These are laid around the bore well pipe which is 30-35 meters deep and the whole system is wrapped with geotextile fabric to restrict the entry of soil into the system. The chamber allows the percolation of rainwater through the borewell pipe via pores made on the pipe while also storing any excess water.

The benefit of the structure is that it is completely underground and its surface can be used for parking, gardening, etc. He said these polypropylene blocks are very strong and can easily bear 5-10 tonnes without requiring any special load-bearing designs whereas conventional pits where nothing can be done on top of the main chamber, with this technology we can put the space to many uses, he informed.

He said that, unlike conventional rainwater harvesting pits in which the drainpipe goes to the main chamber passing through sand or gravel, in the new system, a three-tier framework cleaned the rainwater before allowing it into the borewell. Also, the gravel and the pores on the borewell pipes required frequent cleaning earlier because of silt and clogging by sand and soil. In the case of modular rainwater harvesting pits, the solid waste and silt are sorted by the filter, which can be removed easily for period cleaning without disturbing the entire setup.

He informed that construction causes no dust pollution because polypropylene blocks are used instead of gravel, sand, and dust necessary in the conventional pits. The pre-made blocks are simply ferried to the site and interlocked into place.

Shri Upadhyay said that as per the direction of Hon’ble LG in the meeting held at LG house it was informed that more rainwater harvesting pits to be constructed by all departments of Delhi to recharge the water table. Accordingly, NDMC has prepared a proposal for the construction of 95 Nos. Rain Water Harvesting Pits in NDMC area which will be executed during this financial year 2022-23 and locations of proposed 95 nos. Rain Water Harvesting Pits are yet to be finalized with the consent of the Central Ground Water Board.   

Shri Upadhyay said that this technology uses recycled plastic for prefabricated blocks used in the setup. He said NDMC led this innovative project intending to achieve a 7 Star ranking in the forthcoming Swacchta Survekshan 2022 and NDMC will also submit the project Swachh Bharat Mission (SBM) portal as well. 

He said that the Hon’ble Prime Minister had also urged the citizens of India during a radio programme ‘Mann ki Baat’ to save every drop of water and also recycle and reuse water whenever it is possible and He said team NDMC is committed to implement the vision of Hon’ble Prime Minister of India with true spirit.

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