13.03.2025 11:51
During the drilling works carried out as part of the metro project in Kocaeli, methane gas that was released caused fires at two different points. Associate Professor Özkan Coruk stated that such gas emissions are normal due to the region being an old swamp area, saying, "We had already detected the presence of a layer that would accumulate methane gas at a depth of approximately 30-35 meters."
In the Dumlupınar neighborhood of Kartepe district, during drilling work carried out as part of the metro project on February 17, a fire broke out when they reached a depth of 47 meters. The fire was extinguished on March 4. The company conducting the drilling completed its work by removing the drilling pipe on March 8. During drilling work conducted on March 2 on Ankara Street, which is right next to the D-100 highway towards Izmit, gas that was released 45 meters underground and ignited in a controlled manner by the teams was sealed off with concrete. The fire, believed to be caused by methane gas, continues.
Assoc. Prof. Dr. Özkan Coruk, a faculty member of the Geological Engineering Department at KOÜ Faculty of Engineering, provided evaluations regarding the ongoing methane gas-related fire. Coruk stated that methane gas is a type of gas formed by the decomposition of organic residues, saying, "It is a gas that we encounter frequently, especially in swampy environments. Additionally, methane gas is also found in coal basins and coal mines, which are products of swampy environments. It is a geological formation. It is possible to find pockets of these gases at certain depths, near the surface, and in areas developed after swamps during geological processes."
"IT IS POSSIBLE TO ENCOUNTER METHANE GAS IN THE REGION" Speaking about the methane gas that surfaced at two separate points, Özkan Coruk said, "We were not surprised at all. This is an event we would encounter here. Because the area known as the Izmit Plain, located between Sapanca Lake and Izmit Bay, is an old swamp. This swampy environment still shows traces on the surface. It is possible to encounter this formation up to a depth of 120 meters during geological processes. The gas released as a result of the compression of plant residues and other organic remains in the swamp formation process can accumulate in pockets defined as 'lenses or interlayers' along with groundwater in this environment. We can think of it as a closed system. The accumulation of this gas in similar layers underground, in small or large lenses, is a geological event that develops due to the compression of the overlying cover. Depths may vary, but the likelihood of encountering methane gas accumulation in these pockets in the region is quite high. At greater depths, this gas can transform into a slightly different quality along with groundwater," he stated.
"A FLAMMABLE AND TOXIC GAS" Speaking about the effects of methane gas on humans and the environment, Assoc. Prof. Dr. Coruk said, "When it escapes into the atmosphere, if the volume is not large, and if it does not create a significant gas flow or gas transformation in the environment, it is not harmful. It is possible to control it, but it is a flammable and toxic gas. When you approach it, the likelihood of poisoning in a dense gas environment is high. Its flammable property is its most typical characteristic. When it catches fire, it can turn into a large flame, but over time, it can lose that property and transition into a turbid zone, eventually forming the first step of lignite-like formations. The coals we use today are also products of organic remains that were compressed and accumulated in such an environment in earlier geological periods," he expressed.
"IF WE ARE GOING TO DO TUNNEL WORK, WE NEED TO DESIGN THE EXCAVATION METHOD ACCORDINGLY" Assoc. Prof. Dr. Özkan Coruk stated that projects like the metro project should be carried out considering the presence of gases in the region, saying:
"This could be a drilling attempt, but if we are going to do a tunnel or similar work, which our work here was a metro line; our metro depth continues in a tunnel zone about 30 meters below. In this zone, especially in the section where the Gulf is located, there is a high probability of encountering this zone along our route starting from the area known as the 'old Thursday market' in Izmit district to Köseköy in Kartepe district. If we are going to carry out such a metro work, a tunnel work here, we need to design the excavation method accordingly, taking such a possibility into account. The excavation will be carried out with a machine called a Tunnel Boring Machine (TBM). In such a work, we need to design the TBM considering these risks, place the necessary sensors accordingly, and carry out improvement works in the soil layers in the section where we will open the tunnel, taking these into account. It is certainly possible to improve that zone with cement injection or a similar system, or if we have detected that it is close to the surface from such a gas zone, we need to bring it to the surface in a controlled manner with ventilation shafts and dispose of it."
"WE HAVE ENCOUNTERED SIMILAR CASES BEFORE" Speaking about the initial preliminary work carried out in 2015 as part of the metro project, Assoc. Prof. Dr. Coruk said, "When we conducted the drilling in the first preliminary work on this route, we had already detected the presence of such a layer, that is, a layer that would accumulate methane gas, from about 30-35 meters. We all know that there is such a gas when we evaluate the geology of the region and the formation of the plain because we have encountered similar cases before. In the initial stages of drilling in the region, similar gas emissions occurred. In fact, we have previously encountered such flame ignition cases due to smoking and similar fire starting at the beginning of the drilling without consideration."
"BETTER MEASURES COULD HAVE BEEN TAKEN" Coruk stated that the method of igniting and evacuating the released gas in a controlled manner is one of the correct methods, saying, "They have already tried to evacuate it in a controlled manner, considering the previous case. They even did it by burning and igniting. This can be tried, but better measures could have been taken that would yield better results."
This is at least a step forward. This has been carried out to prevent the harmful effects of the gas and the unpleasant situation caused by the odor by igniting it in this way. In the first case, the gas caught fire and turned into flames without being known. In the second case, this situation was intentionally burned in a controlled manner. It was anticipated that the gas would be consumed in this way," he said.
Assoc. Dr. Coruk warned that methane gas is toxic when inhaled in a closed environment, stating, "The effect of the gas released here is not that significant because its density will decrease in the atmosphere; the concentration will increase. Therefore, it is not toxic, but if you enter the area where that gas is present and breathe, you will be poisoned," he said.