Drains, blocked by design
Rasheed Kappan, Bengaluru, DH News Service, Sep 10 2017, 1:48 IST
Poor design has been the bane of the Storm Water Drains (SWD).
From shoulder drains flanking streets leading to primary drains, secondary canals and eventually to the lakes, the network has been in a perennial mess for years. DH Photo
Trapped in a twister of unprecedented rain woes, as Bengaluru scrambles for solutions in absolute chaos, a long-pending project remains thoroughly incomplete: Remodelling of storm water drains, heavily encroached, designed without foresight and haphazardly networked.
From shoulder drains flanking streets leading to primary drains, secondary canals and eventually to the lakes, the network has been in a perennial mess for years. But when, almost a decade ago, the civic agencies opted to correct the faults, citizens harboured a faint hope.
That hope remains shattered as drains, rarely desilted before the monsoons, overflow within minutes of a shower, flood roads and low-lying residential areas. This is now a daily occurrence even as the redesign work ironically, worsens the chaos.
This is starkly evident in the Lakshmipura and Saraswathipuram areas, adjoining the Rajakaluve leading to Bellandur lake. The project to replace the existing walls with a concrete retaining wall is nowhere near completion. So, when the drain gets flooded in the downpour, water gushes out through breaks in the old wall, broken because earthmovers had to get into the drain for ‘remodelling.’
Motor mechanic Stanley has experienced it firsthand. His automobile outlet gets flooded in knee-deep water overflowing from the drain. “The pace of work has been extremely slow. Most houses in Saraswathipuram bears the brunt of this delay, worsened by the heavy rains this season,” he says.
Life on either side of the drain has been tough for residents of Halasuru, Jogupalya and surrounding areas for years. Residents had learnt to take it in their stride. Yet, what came after the drain redesign work began, was something unprecedented. Explains network engineer Nagarjun M, “The entire floor of the drain is being concretised. There is no space for water to get absorbed and recharge the ground water. This is another primary reason for the water overflowing.”
Since garbage trucks rarely frequent these areas, residents say they have no choice but to dump on the roadside. Most of those bags are thrown right into the drain, clogging the entire canal. Nauseating garbage dumps mixed with the storm water are all over the drain, halting the flow and diverting it over ground.
Shoulder drain woes
If the bigger drains are in such poor shape, the shoulder drains contribute hugely to the mess due to both poor design, zero maintenance and citizen apathy. In Shastrinagar off Old Airport Road, these shoulder drains were cleaned up and concretised over two years ago. The drains were all covered with slabs, but gaps for storm water to enter were not clearly defined and left open. Result: Recent rains have left entire streets and apartment basements flooded.
Heavily encroached and polluted with high inflow of sewage from both residential and industrial units, the drains are incapable of taking the water load to the lakes in a clean form. Built to let water flow according to the dictates of gravity, these drains fail disastrously in low-lying areas.
But there is a solution if the water is seen as a resource to be secured, reminds M N Thippeswamy, former Chief Engineer, Bangalore Water Supply and Sewerage Board (BWSSB). “Build underground tanks to hold rainwater. In low-lying areas, take the entire water load from the drains to these tanks. The stored water can later be used for both potable and non-potable purposes,” he explains.
That has the potential to address a recurring problem in the summer months: Water shortage. But another challenge remains: An estimated 30% of the sewage generated in the city are let directly into the storm water drains. Following unscientific designs, sewage and drinking water / stormwater lines were built close to each other, risking contamination.
Man-holes in drain
Man-holes to access underground sewage lines have been placed right inside the stormwater drains. This, as Thippeswamy points out, not only obstructs the natural flow of stormwater but also weakens the manhole structure, aiding leakage and contamination.
Blatant encroachment of the drains by builders and individuals in connivance with elected representatives and bureaucrats had triggered a demolition drive by the Bruhath Bengaluru Mahanagara Palike (BBMP). But the drive earned public wrath because the entire exercise was sporadic, random and designed to let off the real culprits in governance.
Buildings and layouts on encroached land were approved and registered without physical verification of revenue maps. Thousands of citizens, unaware of the corrupt dealings that got these approvals, purchased the properties and fell victim to the racket. They are now left to fend for themselves as storm water repeatedly enter their houses.
Once encroached, the drains have had their original alignments modified to bypass houses and layouts. Service lines have been laid inside and across lines. Absence of any buffer on either side of the lines have blocked flow of water and access to maintenance. Indiscriminate dumping of garbage and construction debris have made it even worse.