The city that boasts a metro rail continues to fumble in the dark when it comes to the disposal of its sewage.
The three sewage treatment plants (STP) that serve the district are ill-equipped to deal with the enormous volume of waste — approximately 300 mld (million litres per day) that the city generates.
The plant at Elamkulam, operated by the Kerala Water Authority (KWA), has a capacity of 4.5 mld but is operating at an average of 3 mld, says KWA Deputy Chief Engineer P. Gireesan. The underutilisation is attributed to limited connections to the KWA’s sewerage network — 1,184 connections, including the General Hospital, St. Teresa’s College and buildings in the M.G. Road vicinity.
The KWA’s sewerage network has not expanded since these lines and the Elamkulam plant were set up in 1956, Mr. Gireesan says. Land was acquired for five additional pump houses, besides the existing two, to expand the system, but a persistent lack of funds stalled the plans, he adds.
The Elamkulam plant does not have the facility to receive waste from septic tank cleaning vehicles. The facility can be installed and the plant’s capacity also expanded if the Corporation provides the funds, Mr. Gireesan says.
The GCDA operates a small STP at Marine Drive that treats waste from a 2-km sewerage network in the Marine Drive—Shanmugham Road area. It has a capacity of 9 lakh litres and has been operational since 1984, but does not treat waste from tankers.
Since the network of sewers directly connected to a treatment plant is limited, septic tanks are the city’s preferred means of sewage disposal. But well-functioning septic tanks are few, Mr. Gireesan says. A scientifically constructed septic tank allows the waste to degenerate bacteriologically and then sends the effluent into a soakpit where it is filtered through layers of charcoal and gravel before it is released into the ground. “Most houses do not have soakpits and the liquid can leak into the ground directly. This explains the heavy presence of coliform bacteria in almost 90% of groundwater sources within the city,” he said.
Pathogens can only travel 30 m through the ground before they die. But current building regulations permit the tank to be constructed up to 7.5 m away from wells, Mr. Gireesan says.
Regular monitoring of septic tanks is nearly impossible since they are closed and underground, says a Corporation official associated with sanitation. Inspections are done only if visible leaks or direct disposal into drains are reported. Septic tanks attached to soakpits can have capacities between 3,000 and 15,000 litres, he says.
Residents unaware
Residents are also unaware of when the tanks are to be cleaned out and leakage into the soil can go unnoticed, says a member of a septic tank cleaners association. According to a resident in Vennala, the septic tank in his house has been cleaned out only once since his family moved into the house 40 years ago.
Both residential and commercial buildings with over four floors or occupying an area of over 20,000 sq. ft are required to have STPs before a permit is granted by the Kerala State Pollution Control Board (KSPCB). While around 600 apartments in the district may have approached the board for permits since it was made mandatory over a decade ago, the board does not monitor the functioning of the STPs or inspect premises for its presence, says a KSPCB official.
Waste from the septic tanks is treated at the Corporation’s two plants with limited capacities – one at Brahmapuram and the other at Willingdon Island. While the Brahmapuram plant was set up to handle 20 tanker loads of 50,00 litres each, it can currently handle only 12 loads. The plant at Brahmapuram began functioning in December 2016 and the one at Willingdon Island, with a capacity of 20 tanker loads, began operations in 2018. Where the untreated waste collected by the tank cleaning vehicles went before these plants become operational only a few years ago is anybody's guess.
While the Corporation does not track the tankers or keep a record of their numbers, it grants passes into the treatment plants to three septic tank cleaning associations in the district. Considering the capacity of the plants, only 32 vehicles can dump their waste at the plants in a day. Each of the three associations has around 30 members and over 40 vehicles, members say. The Corporation charges a fee of around ₹470 for a 24-hour gate pass into the plant. To avoid these charges, agencies could operate without registering with the associations as well and their waste would not reach the treatment plant, a member says. Owing to the stigma attached to the job and that regular cleaning runs may not be required, the number of tankers and agencies fluctuates often, another member says. The waste generated, particularly the sludge from the STPs at large hotels, apartments and hospitals, far exceeds the capacity to treat it, he adds.
Though both plants operate all day, the tanker loads come in only at night, says Kiran Surya, an environmental engineer at the Corporation. At Brahmapuram, public protests against the smell led to demands for operation after 6 p.m., he says. To avoid the stigma associated with waste disposal, tanker staff would also rather conduct operations at night, says a member of a cleaning association. Technology at the 63-year-old treatment plant in Elamkulam, which releases treated water into the Chilavanoor lake, has become obsolete, Mr. Gireesan says. Better technology that would allow the use of smaller tanks and more advanced techniques for bacteriological activation is required. The Cochin Smart City Mission has proposed to set out ₹70 crore for the modernisation of the plant and expansion of the collection system. Tenders have been invited but there are no successful bidders so far, he says.
The KWA does not come up with proposals to expand the system because of fear of opposition to the digging and laying of pipelines, Mr. Gireesan says. The high groundwater table in the city makes the laying and maintenance of sewerage pipes difficult since the gravity flow of sewage depends on pipes being laid on an incline. The pipelines in some places may have to be laid at depths of 3 m or more underground and will have to be entirely watertight to ensure the groundwater is not affected, he says.
The Cochin Smart City Mission has also proposed a ₹22-crore sewage treatment and collection system for West Kochi. Plans for a treatment plant for West Kochi at Mundamveli under an ADB-funded KSUDP project fell through when the land procured for it was found to have violated Coastal Regulation Zone (CRZ) norms. Landfilling for the STP was taken up at a cost of ₹3 crore and pipes worth ₹18.81 crore bought for the project are lying idle, according to a CAG audit report from 2016.
The Corporation prepared a city sanitation plan in 2014 that sets a framework for the next 30 years to increase the sewerage network in the city and conduct surveys of septic tanks. Besides the Smart City projects, the Corporation has no ongoing plans to expand the treatment capacity or network, says Pratibha Ansari, chairperson, health standing committee of the Corporation.
The condition of the waterbodies in the city can be improved only if the sewerage network and treatment capacity is expanded, says Mini Mary Sam, engineer, KSPCB. But the board is understaffed and unable to take up regular monitoring, she says.
