PNLIT Chronicles: Diverting Rain Water into the Lake

By Usha Rajagopalan

It was exactly seven years to the month that we began our venture to tap rain water from new sources into our Puttenahalli Lake. In July 2011, two months after signing the MoU with the BBMP,  we zeroed in on the surface run off from the Brigade Millennium avenue to the north of the lake that was otherwise getting wasted. Within the complex, it flowed down proper storm water drains but beyond this, it was not channelized and followed the natural slope of the land to flood the area below. Enzen Global Solutions offered to do a total station survey which confirmed the possibility of harvesting this water. Two years later, BBMP approved the project and, in early 2013, their contractor began the work.

It was not an easy task because it involved collecting rain water into a shallow trench built across the road which would have a grill on the top sturdy enough to withstand heavy traffic. Even then, the force of the water rather than the gradient would divert the water into the lake. To begin work, the incessant traffic had to be stopped or diverted.

The “Diversion Channel” was completed before the monsoon set in. What a thrill it was to see water enter the lake after the first pre-monsoon rain in May 2013!  Several of our regular visitors made it a point to visit the lake just after a shower to see this. One of them, Mr. Rajesh Agrawal from Brigade Millennium, even took a short videoon 16thAug.  Such was the force that the water dislodged the boulders in front of the silt trap. We got concrete steps made with stones sticking out to catch the plastic and other trash that flowed in with the water. That year, half the lake bed was submerged.

Unfortunately, the Diversion Channel was active for just two monsoons. In early 2015, we found that to reduce the gap between the rods in the grid someone had welded smaller ones in between. The new rods were lightweight and gave way so they covered it with sand and soil. By July 2017, the road was tarred and the grill buried under.

We are back to square one. Rather than confront those who preferred to destroy and terminate over trying to revive and strengthen, it is easier for us to approach BBMP. This time we are trying to get them to redo the grill – with studier, flat rods that will withstand human interference and vehicular load. Till then, we will have to bear the sight of precious rain water wash down the road, away from the lake, and go waste.