Oil separated water needs lab test: Experts
Source: The Sangai Express

Imphal, January 13 2024: Even as the heavy oil spill from Leimakhong Power Plant has caused oil effluent dis-charge in the Khanglapokpi Khong and a few minor channels, major contami-nation to several rivers and streams has been averted, said a report of field inspections published by experts in the National Institute of Technology, (NIT) Manipur.

As of now, the spillage of oil is insignificant as the thickness of oil is less than 3 mm, said the expert team detailing methods to trap the oil and remedial measures to be taken up.

The experts said the oil separated water still needs to be tested in the laboratory for toxicity and other related carbon compounds.

The expert team of NIT Manipur included Dr Ng Romeji (Hydrologist), Prof (Dr.ing) Bakimchandra (Head/GIS expert), Prof Dr Albino Kumar (Environmentalist) and Dr Azhoni (Climate expert).

They were accompanied by Asst Registrar L Dorendra and PhD/PG students.

Preliminary test investigations of water samples collected at three sites indicate that the water is alkaline, though highly contaminated with oil leakage from the power plant, the report said.

It noted that the immediate action taken up by constructing a bund to divert the oil effluent flow from flowing downstream into the adjoining paddy fields has prevented contaminant transport into the main Luwanglei stream and Leimakhong river which otherwise may have contaminated the Nambul River and the Imphal River.

The Luwanglei stream discharges into the Nambul River at Taothong-Iroi-shemba and Leimakhong River discharges into the Imphal River at Nilakuthi.

As of now, the spillage of oils is insignificant with an oil thickness of less than 3 mm and most of the oil has been trapped using bamboo baffles within a stream length of 50-60 m .

The experts however noted that the Nambul River may be in danger if the effluent persists.

Traces of oil effluent are observed in small contents at the confluence point of Khanglapokpi Khong and other minor drainage channels in Leimakhong and Khurkhul and further down to Luwanglei stream.

The effluent discharge if persists along Luwanglei stream, will flow down through Loitang Khunou, Kameng, Mayang Langjing and Lamdeng before discharging into the Nambul River.

The Nambul River is already at alarming levels of pollution and further oil contamination will degrade the river ecosystem health, said the experts.

Meanwhile, leakage of the oil in the adjoining fields is still visible, said the report.

Methods to trap and remove oil The NIT experts suggested methods to trap and remove the oil from the surface of the water.

One of the most effective oil removal/traps is the separation of oil from water through the introduction of baffle walls where water which is heavier than oils would freely escape below and the oils would be trapped on the top, said the team.

Baffles are flow-directing or obstructing vanes or panels used to direct a flow of liquid or gas.

Firstly, a wood plank of not less than 2 feet may be provided as baffles with one foot above the water level to prevent overflow and spillage of oil.

Once the oil level reaches more than 6 inches, the oils may be pumped off using a 0.5 HP pump maintaining minimum turbulence, and the oil may be dried and burned off.

Proper monitoring should be done with a site engineer to make the arrangement effective, noted the experts.

Further findings

During the in-situ site sampling of the contaminated water, pH (potential of hydrogen) values in upstream source point at Khanglapokpi was found to be 7.75 .

At the diversion point at Khanglapokpi pH was found to be 7.19 and at downstream point where Khanglapokpi and minor drainage confluence with Luwanglei stream, pH was found to be 7.63 suggesting the ability of the stream to dilute at downstream.

The Total Dissolved Solids (TDS) recorded at the three respective locations were found to be 218.5 ppm, 103.3 ppm and 69.85 ppm, indicating the minimal presence of effluents and oil contamination in the minor channels at the present state.

However, oil separated water needs to be laboratory tested for toxicity and other related carbon compounds.

The other contaminant transport is under tests at the laboratory of CED, NIT Manipur.

This will further give insights into the water quality and safety criteria for potability.

Further downstream, no contamination was observed in the Leimakhong River at Kanto Sabal and Khongampat-Nilakuthi areas.

This indicates that the Imphal River is relatively safe from oil effluents, said the report.

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