CHENNAI: Measures taken by the Oil and Natural Gas Corporation Limited (ONGC) to control incidents of oil leakages from a network of underground pipelines in the delta region of Thiruvarur district are inadequate, said a joint committee appointed by the southern bench of National Green Tribunal (NGT) in its interim report.
The committee was looking into repeated ONGC pipeline leakages in Thiruvarur district, where it has been carrying out operations for the last three decades. There was one leak on April 28 this year in Keezhapadugai village and another on April 6 last year in KeezhaErukkattur village. There were also a few other minor leaks in between and local villagers are in constant tussle with ONGC officials over alleged soil contamination due to their operations. The NGT took up the issue on its own motion suo motu based on the reports received from the Tamil Nadu Pollution Control Board (TNPCB).
The committee, which consisted of Thiruvarur district collector, officials from TNPCB, Central Pollution Control Board (CPCB) and Tamil Nadu Agriculture University (TNAU), has conducted a preliminary meeting online on June 30 with the ONGC officials from Cauvery Asset.
ONGC officials have presented the action taken report to the committee on the pipeline leakages and said it had replaced the old damaged pipeline with the new ones, besides paying the affected farmers compensation. It can be noted that several acres of agriculture farms were contaminated during the oil leakages. The company officials have also briefed about control measures to avoid future pipeline leakages like following flow based monitoring to identify the leakage in flow lines at the receiving end and leak detection system being incorporated in the recently laid trunk lines.
However, the committee felt that the steps taken by ONGC for the control of pipeline leakage are not sufficient, because the leakages and its locations are being identified after physical appearance of
oil on the soil surface.
"Present method of flow based measurement at receiving end to identify the leakage of oil is not effective, because exact location of oil leak point is not able to be identified until its physical appearance in the top soil. The flow based measurement shall be carried out by providing flow meters in all pipelines with certain distance from well to receiving point, so that the area of pipeline leak shall be identified easily at initial stage itself. These flow meters shall be connected to any system like SCADA, PLC etc," the interim report said.
Also, the committee suggested the periodic assessment of pipe integrity (including internal crack, corrosion & erosion) to be made at least once in five years, so that the status of the pipeline shall be known and accordingly replacement period for the pipe shall be decided.
External corrosion protection of pipelines needs to be provided in all underground pipelines such as sacrificial anode method, impulse current method, polyethylene coating etc. "ONGC has informed that old pipelines are flushed once if it is not going to be used further in future. Evidence shall be provided to the committee during field visit to ensure that old unused pipelines are flushed properly," the committee said.
Meanwhile, the committee has requested the NGT bench for six weeks more time citing the pandemic to conduct field visits and submit its final report.
Considering the COVID-19 situation, the NGT bench, comprising Justice K Ramakrishnan and expert member Saibal Dasgupta, has granted two months time to the committee to submit the report.