The polluted water drains into the lake, saving its surrounding areas from flooding
The air in the Hatirjheel area reeks of sewerage, one palpable sign of the expensive project going wrong.
Hatirjheel lake had a makeover about half a decade ago to turn into a clean and attractive place, but its engineers knew it would soon lose its shine to the city's age-old, broken sewerage network.
This matter of concern soon became a reality. The 300-acre waterbody was designed to retain rainwater flowing down from adjacent areas, but the project failed to do that. The lake has ended up becoming a septic tank.
Passers-by get nauseated by the strong odour that emanates from the lake now.
The authorities rushed to do a quick and expensive fix in July 2018, without actually achieving a permanent solution. They started a one-year project to improve the quality of the water to a tolerable level through chemical treatment and supply of oxygen.
Experts, however, say that this action will not be able to sustain changes if the authorities continue to be indifferent to solving the root cause of the problem – that rainwater mixes with household waste and sewerage during the rainy season in the absence of separate pipelines.
The polluted water drains into the lake, saving its surrounding areas from flooding.
The immediate solution
The water level drops during the winter, thereby intensifying the pollution. An Australian firm named Neville Parker and Co was commissioned last year to treat the water with the help of a local partner.
Since the testing of water samples and determining the chemical treatment took more time than expected, the project has been stretched up to this year.
Machines will be installed within the scheduled time at the bottom of the lake to oxygenate the water, the same way as it is done in an aquarium. This is necessary because the level of oxygen in the water has become far too low to allow the survival of fish and other aquatic organisms. And chemicals will be used to sediment the floating filth.
A dredger like machine will also be put in place to dredge out household waste and sewage sludge from behind the Pan Pacific Sonargaon Hotel.
The Panthapath box culvert has been identified as the major source of pollutants. This is the point where waste coming from Karwan Bazar, Dhanmondi, Paribagh and other nearby areas accumulates.
The cost of rectification has been estimated to be Tk49 crore over a period of two years.
People living around the lake will experience a better environment if the machines are well maintained and the use of chemicals continues at an additional cost every year for the next five years, said Lieutenant Colonel Kazi Shakil Hossain, director of the Hatirjheel lake water purification project.
Why the Hatirjheel project failed
But why has Hatirjheel, instead of being a rainwater storage facility, became a sewerage pond? The answer lies with its design.
The purification efforts had not been a component of the main design because the lake was supposed to be the largest body of freshwater in the capital.
When engineers from the Bangladesh University of Engineering and Technology (Buet) set off to draw the lake's layout, they discovered that the gates intended to keep waste from entering the lake will have to be opened after a heavy shower. Otherwise, an overflow of water and filth would inundate this part of the city.
There is no underground sewerage network in places such as Badda, Banani and Gulshan, and the old pipelines set in Moghbazar and Eskaton decades ago are mostly broken.
In fact, the existing sewerage network in Dhaka can cater to only about 20 percent of its more than a million people, said Professor Mujibur Rahman, head of the Buet team that worked on the Hatirjheel project.
The network was built in the 1960s and has never been repaired, developed and expanded. People have continued to build new structures and connect the outlets of their sewerage pipelines directly to the drainage system.
Moreover, when the old network gets clogged at any place, pipelines are cut off letting the waste flow into the stormwater drainage system.
Without a proper sanitary system at least in areas adjacent to Hatirjheel, Prof Mujibur said, "The lake will become a sewerage pond."
Back in 2008, engineers suggested installing sewerage pipelines to carry waste to Dasherkandi – 10 kilometres away from Hatirjheel lake. A treatment plant will have to be set-up there to treat the waste water before discharging it into rivers, canals or any other waterbodies.
The Dhaka Water Supply and Sewerage Authority (Wasa) began constructing the Dasherkandi plant one and a half years ago. It will take another year or more to complete it.
But even if the plant is ready, the major task of installing pipelines to carry the waste to it has not yet begun. The plant will sit idle without the sewerage network.
The Business Standard repeatedly tried to contact Wasa Managing Director Taksim A Khan over the phone for comments, but he did not respond to calls and messages.
Meanwhile, the army has completed a sewerage network from Kathalbagan to the Panthapath box culvert, from where the sewerage is diverted to the Rampura canal. From there the waste should go to the Dasherkandi treatment plant.
Quick solution to become expensive
Considering the pace at which Wasa is setting up pipelines, it will take another 20 years to finish the job of the entire network, said Colonel Shakil, director of the Hatirjheel lake water purification project.
Until then, chemical treatment will continue to save Hatirjheel lake from pollution.
A yearly budget of Tk17 crore has been proposed to the public works ministry for the maintenance of the lake. The cost includes the money needed for chemicals and the operating expenditure of the machines set up under the purification project.
"Maintenance will become expensive if the temporary solution has to continue for a long time," Prof Mujibur said.