Investigation report on secondary major environmental emergencies caused by diesel oil leakage accident of Sinopec Southwest Product Oil Pipeline in Tongzi, Zunyi, Guizhou

　　At about 6: 06 on July 14th, 2020, the diesel oil in the southwest refined oil pipeline of Sinopec in Tongzi County, Zunyi City, Guizhou Province leaked, which caused a major environmental emergency that affected Guizhou and Chongqing provinces. After the incident, the Ministry of Ecology and Environment quickly sent a working group to guide Guizhou and Chongqing to carry out emergency response work. Through joint efforts, the emergency goal of "ensuring the safety of drinking water and preventing excessive sewage from entering the Yangtze River" has been achieved.

　　In accordance with the relevant provisions of the Measures for the Investigation and Handling of Environmental Emergencies (Order No.32 of the Ministry of Environmental Protection), the Ministry of Ecology and Environment initiated the investigation procedure for major environmental emergencies, and joined forces with the Guizhou Provincial Department of Ecology and Environment, the Chongqing Municipal Bureau of Ecology and Environment, and the Yangtze River Basin Ecological Environment Supervision Administration to hire relevant experts to set up an investigation team to investigate the major environmental emergencies secondary to the diesel oil spill accident in the southwest refined oil pipeline of Tongzi Sinopec in Zunyi, Guizhou. According to the principle of "seeking truth from facts, being objective and fair, and being consistent in power and responsibility", the investigation team determined that this incident was a major environmental emergency that caused cross-provincial pollution due to factors such as landslide and improper pre-disposal.

　　I. Basic information

　　China Petrochemical Sales Co., Ltd. South China Branch (hereinafter referred to as Sinopec South China Branch) was established on November 26, 2006. It is the agency of China Petrochemical Sales Co., Ltd., and China Petrochemical Sales Co., Ltd. is a wholly-owned subsidiary of China Petrochemical Co., Ltd. The incident occurred in Jiezhen Village, Xinzhan Town, Tongzi County, Guiyang-Chongqing section of the product oil pipeline (pipeline pile number ZY109+410). The total length of the pipeline is 362km, the designed transportation capacity is 5.8 million tons/year, the design pressure is 9.5Mpa, the pipe diameter is 406mm and the wall thickness is 8.7 mm.. The whole pipeline adopts closed sequential transportation technology, which sequentially transports 92# gasoline and 0# diesel, and adopts SCADA control system (remote data acquisition and monitoring system) to transport 0# diesel when the accident occurs.

　　(II) Incident and pollution process

　　At 6: 06 pm on July 14th, the duty officer of Sinopec South China Branch found a diesel oil leak in the pipeline. At 14: 00 on July 14th, the oil concentration at the junction of Songkan River in Guizhou and Chongqing began to exceed the standard (refer to Class III standard of Environmental Quality Standard for Surface Water (GB3838-2002)Ⅲ) of 0.05mg/L, the same below); At 16: 45 on the 14th, the pollution front arrived at the water intake point of Songzao Coal Mine; At 8: 35 on the 15th, the pollution group vanguard arrived at the water intake point of Sanjiang No.4 Steel in Qijiang District; At 9: 10 on the 16th, the front of the pollution group arrived at the exit section of Qijiang District; At 16: 20 on 16th, the vanguard of the pollution group arrived at the drinking water source in Guangxing, jiangjin district.

　　The water quality of monitoring sections in Chongqing reached the standard at 6 o’clock on July 18th, and that of monitoring sections in Guizhou Province reached the standard at 6 o’clock on July 19th.

　　(3) Direct economic losses

　　According to the assessment, the emergency response phase of this sudden environmental incident caused a total direct economic loss of 1,487,300 yuan, including 895,400 yuan in Guizhou Province and 591,900 yuan in Chongqing.

　　(4) Environmental impact

　　According to experts’ accounting, the diesel oil leakage in this incident was about 289.91 tons. Among them, about 252.21 tons were recovered, 3.67 tons were adsorbed, 20.58 tons were put into soil and 13.45 tons were put into river. The incident caused the oil in a total of 119 kilometers of rivers downstream of the accident site, including Jiezhen River, Songkan River and Qijiang River, to exceed the standard. Sanjiang Waterworks in Qijiang District stopped taking water for 19 hours because the quality of drinking water source exceeded the standard, thus reducing the water supply area. 4.5 mu of farmland around the accident site was polluted, and the contaminated soil was about 461.9 tons.

　　Second, deal with the disposal

　　After the incident, the governor of Guizhou Province, the deputy governor in charge, the secretary of the Chongqing Municipal Party Committee, the mayor and the deputy mayor all gave instructions, and a working group was sent to give on-site guidance on July 14. The Ministry of Ecology and Environment immediately sent a working group to the scene after learning the incident information on July 15th to guide the local authorities to do a good job in source blocking, interception and adsorption, renovation of water plants, and dilution along the way, and put forward the emergency goal of "ensuring the safety of drinking water and preventing the sewage exceeding the standard from entering the Yangtze River". Sinopec South China Branch took timely measures such as stopping transportation, closing valves and relieving pressure, and the people’s governments of Zunyi City and Tongzi County started emergency response at different levels, urgently assembled rescue forces and carried out on-site emergency treatment. The People’s Government of Qijiang District of Chongqing Municipality immediately arranged emergency monitoring, water intake from waterworks at wrong time, pollution disposal and information announcement after receiving the relevant incident information at 8 o’clock on July 14th, and informed the downstream jiangjin district in time. The People’s Government of jiangjin district arranged to be on duty 24 hours a day to observe the water source situation and carry out water quality monitoring. The rapid response of Chongqing ensured that the water supply safety of residents was not affected when the water quality of related water sources was affected, which ensured public opinion and social stability.

　　(2) Cut off the source

　　After the leakage was discovered on July 14th, Sinopec South China Branch stopped oil transportation urgently, quickly closed the ban qiao valve chamber, Yelang valve chamber and Dongshan valve chamber upstream of the leakage point, and relieved the pressure of Yaolongshan Station downstream of the leakage point through large-flow relief. At 6: 34, more than 280 people were put into the site to carry out emergency treatment, as well as 8 excavators, 21 tankers, 14 pumping equipment, 1,680m boom, 210 bags of oil-absorbing felt and other emergency materials. The plugging was completed at 10: 00 on July 15th.

　　(3) Pollution control

　　1. River pollution control. There are 31 oil booms in this incident, including 15 in Guizhou Province and 16 in Chongqing. Guizhou province has also built 12 oil dams, 12 activated carbon dams and 1 oil separation tank in China, reducing pollutants by about 3.67 tons. 14.01 tons of diesel oil was recovered by oil collector.

　　2. Soil pollution control. In the disposal of this incident, five drainage ditches were set up near the upstream of the leakage point, and an oil sump was set up downstream of the leakage point to collect the leaked diesel oil and oily rainwater, which was used to intercept and lead out the rainwater and surface runoff, and the leakage area was covered with a rainproof cloth of about 2882m m.². After the emergency disposal, 461.9 tons of contaminated soil was cleared.

　　(4) drinking water security

　　Chongqing implemented emergency renovation of the affected waterworks, and Sanjiang Waterworks in Qijiang District reduced the water supply area in time. From July 15th to 17th, the Qiaohe and Tuowan areas in the original water supply area were changed to Wenlong Waterworks. At 4 o’clock on July 16, Sanjiang Waterworks met the water supply requirements through technological transformation, and the water demand of residents was met.

　　(5) Information disclosure

　　On July 16th, Guizhou Province released the accident information and preliminary disposal to the public through the platform of Loushan Information. On July 16th and 18th, Chongqing Qijiang District Emergency Bureau released event information through the public information early warning platform three times. On July 15th, Chongqing Yuqian Water Technology Development Co., Ltd. released the Notice of Insufficient Water Pressure in Some Urban Areas Due to Water Pollution of Qijiang River on the Damei Qijiang APP.

　　Third, the direct cause of the incident

　　The direct cause of this incident is that the landslide caused the oil pipeline to be squeezed, resulting in displacement, deformation and local damage, resulting in diesel oil leakage, which in turn caused cross-provincial pollution.

　　(A) the main causes of landslides

　　Experts believe that the landslide of Yanshang Formation in Jiezhen Village, Xinzhan Town was formed under the influence of concentrated heavy rainfall, unfavorable topographic and geomorphological conditions, unfavorable geotechnical structure and other major factors, and it is a geological disaster caused by natural factors.

　　(II) Causes of the leakage accident

　　After the landslide, the front soil was pushed down, which caused the pipeline ZY109+410 buried in the soil to be squeezed, resulting in displacement and local damage, which led to the leakage accident. In the process of finding the leakage point, the organization excavation disturbed the balance of the leakage point, resulting in a large number of diesel oil leakage and the pollution situation expanded.

　　Fourth, the main problems

　　Before the incident, Sinopec South China Branch did not fully judge the information that landslide threatened the pipeline safety, and did not take timely measures to eliminate the hidden dangers of pipeline safety and avoid the leakage of pipeline transportation medium to pollute the environment when the relevant competent departments put forward the requirements of stopping transportation, resulting in pipeline damage and oil leakage, which entered Songkan River through Jiezhen River, causing environmental pollution.

　　(two) improper disposal in advance, causing a large number of leaks

　　After finding diesel oil leakage, Sinopec South China Branch took measures such as stopping transportation, digging oil sump and setting oil booms, which basically controlled the spread of leaked diesel oil downstream through Jiezhen River. However, without fully evaluating the remaining oil in the pipeline, without fully considering the risk that external forces may disturb the existing equilibrium state and the pollution prevention and control measures such as oil collection pits and diversion canals are not fully prepared, the oil leakage point is organized to be excavated, resulting in a large amount of diesel oil pouring into Jiezhen River, and the pollution situation is expanding.

　　(C) the relevant departments of the local government failed to perform their duties in time.

　　Zunyi City Bureau of Industry and Energy, Tongzi County Economic and Trade Bureau, Emergency Management Bureau and other units received the information that the landslide threatened the pipeline safety reported by Sinopec South China Branch, and the relevant personnel all replied to go to the scene the next day to check, but did not rush to the scene to coordinate and eliminate hidden dangers or report to the people’s government for timely organization to eliminate potential safety hazards, and failed to conscientiously perform their duties of protecting oil and gas pipelines. The Zunyi Municipal Bureau of Ecology and Environment and the Guizhou Provincial Department of Ecology and Environment failed to report the incident information to the Zunyi Municipal People’s Government and the Ministry of Ecology and Environment within the time limit specified in the Measures for Reporting the Information of Sudden Ecological and Environmental Events after receiving the incident information.

　　(D) The structure of emergency headquarters in Zunyi City is unreasonable.

　　The July 14th incident caused cross-provincial pollution, which has constituted a major environmental emergency, and the Zunyi Municipal Government should organize and direct the response. However, the on-site emergency response has been stepped down. The commander of the on-site command department is in turn the person in charge of relevant functional departments of Zunyi City, the executive deputy magistrate of Tongzi County, the deputy magistrate in charge of Tongzi County, and the person in charge of Sinopec South China Branch. The structure of this incident headquarters is inconsistent with the relevant provisions of the National Emergency Plan for Environmental Emergencies and the Emergency Plan for Environmental Emergencies in Zunyi City.

　　(E) inadequate linkage between government and enterprises

　　Poor communication between local and enterprise information. Before the July 13th incident, the relevant staff of Sinopec informed the local village committee that 92# gasoline was transported in the pipeline. On July 14th, when the oil spill increased sharply at the initial stage of emergency response, local government personnel at the scene still thought that the oil was leaking, and they urgently organized the evacuation of local people, only to learn that the company had changed the transportation of gasoline in Zunyi section to diesel. In the early stage of accident rescue, local rescuers and enterprise rescue forces acted in their own way, and the local authorities did not understand the daily management of pipeline enterprises, so they could not contact and dock with enterprises at the first time after the incident, which affected the rescue effect.

　　(six) the upstream and downstream linkage is not perfect.

　　Tongzi County, Zunyi City reported the incident information to Chongqing Qijiang District Ecological Environment Bureau for many times on July 14th, which provided strong support for Chongqing to prepare for emergency. However, in the information notification, the emergency monitoring data, diesel oil leakage and disposal measures were not notified in time. Due to the lack of relevant information, it has affected the research and decision-making of the Qijiang District Command on the pollution situation, and we can only do our best to make relevant work arrangements and preparations based on experience.

　　Five, prevention and rectification measures and suggestions

　　1. Intensify training. After the institutional reform, the "big emergency" management system was basically established, but the response mechanism for comprehensive emergencies was not perfect. For example, this incident was caused by a production safety leakage accident caused by a natural disaster, and then it evolved into an environmental emergency. Under this situation, the government leaders’ understanding of relevant plans and emergency decision-making management ability were even more tested. It is necessary to increase the relevant contents of environmental emergency management in special training, conference discussion and comprehensive training, strengthen the training of environmental emergency management for government leaders, and further strengthen the ecological environmental protection awareness of emergency command and dispatch and emergency response personnel of local governments, departments and enterprises, improve the ability of judgment, command and dispatch and response to sudden environmental incidents, and do a good job in emergency response in the whole process to avoid.

　　2. Strengthen the guidance on the revision of the government’s environmental emergency plan. It is necessary to strengthen the effective connection between the government’s special emergency plan for environmental emergencies and the overall emergency plan for emergencies, the emergency plan for natural disasters and the emergency plan for production safety accidents, clarify the emergency command system, emergency response procedures and the responsibilities of various departments, organize emergency drills in a timely manner, and improve the cross-regional and cross-departmental linkage mechanism. In view of the problems exposed by this incident, in 2021, Zunyi City, Guizhou Province and Qijiang District, Chongqing City will carry out an emergency drill for cross-provincial environmental emergencies to test the effectiveness of emergency command, departmental linkage and upstream-downstream linkage mechanism.

　　(B) Improve the level of risk prevention and control and emergency response capabilities of pipeline enterprises.

　　All pipeline enterprises should attach great importance to environmental risk management, prepare environmental emergency plans on the basis of environmental risk assessment, and make a good connection with government plans; Improve the pipeline environmental risk management system, refine the risk prevention and control measures from the perspective of avoiding environmental pollution, regularly carry out self-inspection of environmental risks and make timely rectification. Enterprises should reserve necessary emergency materials and equipment in accordance with the requirements of the plan, strengthen personnel training, strengthen information communication with local governments and relevant departments, establish a working mechanism of mass prevention, mass prevention and treatment, organize regular environmental emergency drills and training, and continuously improve the comprehensive emergency response capability.

　　1. Improve the ability of environmental emergency monitoring at the grass-roots level. It is necessary to strengthen the integration and analysis of emergency monitoring equipment, personnel and other resource information, increase the skills training of grassroots monitoring personnel, especially the training of non-conventional pollutant monitoring personnel, and establish and improve the system and mechanism for social monitoring forces, including enterprises with monitoring capabilities, to participate in emergency monitoring of sudden environmental incidents, so as to ensure timely supplementary support in response to incidents.

　　2. Strengthen the capacity building of environmental emergency rescue at the grass-roots level. All localities should reserve materials and equipment such as cutting off, controlling, collecting, degrading, safety protection, emergency communication and command, and emergency monitoring according to the characteristics of environmental risks in administrative areas. It is necessary to dynamically standardize the management of environmental emergency materials information and improve the environmental emergency materials information management system. Strengthen the training of knowledge and skills of grass-roots environmental emergency management personnel and rescuers in dealing with all kinds of sudden environmental incidents, and improve the professional level of environmental emergency.

　　(4) Accelerate the construction of joint prevention and control mechanisms for upstream and downstream.

　　All localities should, in accordance with the requirements of the Guiding Opinions on Establishing a Joint Prevention and Control Mechanism for Sudden Water Pollution Incidents in the Upstream and Downstream of Inter-provincial Watershed, accelerate the signing of a framework agreement for joint prevention and control of sudden water pollution incidents in the upstream and downstream of inter-provincial watersheds. The upstream area should focus on information such as water conservancy dams and environmental risk sources, while the downstream area should focus on hydrological information such as river flow and velocity, as well as environmentally sensitive target information such as important lakes and reservoirs and drinking water sources. In view of the key rivers with large environmental risks, many sensitive targets, large flow and fast flow rate, the "one river, one policy" joint prevention and control scheme can be jointly formulated. Upstream and downstream areas should vigorously carry out joint emergency drills, timely test the effectiveness of joint prevention and control mechanisms and related emergency plans, and effectively improve the coordination and cooperation capabilities of upstream and downstream in rapid response, emergency monitoring and emergency response.

　　The security of drinking water sources involves water conservancy, agriculture and rural areas, health, urban management, ecological environment and other related departments. During the response to this incident, it was revealed that the water plant had shortcomings in water quality monitoring and advanced treatment capacity. It is suggested to strengthen the capacity building of biological early warning and monitoring of comprehensive toxicity in water sources, and establish a multi-sector safety guarantee mechanism for drinking water sources from early warning, monitoring, emergency response and standby water source construction.