Yiyang city black and odorous water body remediation rebound water body black and odorous phenomenon prominent

Source: Hunan Ecological Environment

With the approval of the Provincial Party Committee and Provincial Government, five provincial ecological and environmental protection inspection teams were stationed in Changsha, Xiangtan, Chenzhou, Yiyang, Loudi and other five cities in late June to carry out the second round of routine inspections of the first batch of provincial ecological and environmental protection for a period of 20 days. Each group went deep into the front line and on-site to verify a group of prominent ecological and environmental issues, and verified a group of formalistic and bureaucratic issues such as inaction, slow action, lack of responsibility, and even perfunctory response and fraud. In order to strengthen warning and deterrence, and promote problem rectification, the first batch of 5 typical cases are now centrally and publicly announced.

In June 2023, during the supervision of Yiyang by the Fourth Provincial Supervision Group for Ecological Environment Protection (hereinafter referred to as the Supervision Group), it was found that the remediation measures for the black and odorous water bodies in Yiyang City were not effective, the feedback problems were repeatedly not rectified in place, and the black and odorous water bodies were prominent.

1、 Basic information

In 2018, provincial environmental protection supervisors reported that the rectification of black and odorous water bodies in Yiyang City was untrue. In 2020, the provincial ecological environmental protection inspector "looked back" again pointed out that the black and odorous water in Yiyang City was not well treated. In December 2021, Yiyang City reported the above problems and completed the rectification. On March 31, 2022, the Bureau of Housing and Urban Rural Development of Yiyang City released the Deepening Rectification of Urban Black and Odorous Water Bodies in 2021 on the official website, pointing out that "through the deepening of rectification and long-term management, the urban black and odorous water bodies in our city have been completely eliminated at present, realizing a long-term clean". However, when the inspection team inspected the built-up area of Yiyang City, it found that the middle trunk canal, Baimashan canal, Dafeng electric drainage canal and other channels returned black and smelly; Spot check of Taojiang County, Yuanjiang, Nanxian County and other counties and cities shows that black and odorous water bodies still exist.

2、 Existing problems

（1） Black and odorous return of water bodies in built-up areas

The inspector found that the water bodies of the Zhonggan Canal, Baimashan Canal, and Dafeng Power Drainage Canal, which have completed rectification and cancellation, have returned to black and have a significant odor. The inspection team found in the Shuncheng Gas Station (Xuefu Road) section of Longguangqiao Street, Heshan District, the middle trunk canal that the sewage interception around the canal was not in place in the area of Hunan City University, Yiyang Medical College, Country Garden Community, Yangwuling Community and other areas, and the sewage was mixed into the canal. The black water in the canal gave off strange smell, and black flocs were floating in it. The on-site sampling monitoring showed that its dissolved oxygen was 0.754 mg/l Ammonia nitrogen is 12.8 milligrams per liter, indicating a mild black odor. Baimashan Canal belongs to the end of urban drainage in Ziyang District. It has been assigned by the province and the city for many times due to the problem of black odor, and has been included in the list of "Dongting Qingbo" problems in Yiyang City. Field monitoring shows that the dissolved oxygen in the Baimashan Canal near Senhua Wood Industry is 0.817 mg/L, and the ammonia nitrogen is 16 mg/L, belonging to severe black odor. The Dafeng Electric Drainage Canal in Heshan District is adjacent to the Tuanzhou Port Sewage Treatment Plant. Although there is a sewage interception pipeline in the middle, the sewage interception is not perfect. The water on both sides of the pipeline is black gray, and a pungent odor can be smelled on site. The on-site sampling monitoring shows that the dissolved oxygen is 0.818 milligrams/liter, and the ammonia nitrogen is 27.3 milligrams/liter, belonging to a severe black odor.

（2） Slow rectification of black and odorous water bodies in some counties (cities)

In 2022, the Yiyang Supervision Office (Issue 49) issued by the Yiyang Municipal Party Committee Supervision Office reported the problem of black and odorous water in Qixing River, Taohuajiang, Taojiang County. This inspection found that the surrounding West Street Courtyard, West Street Garden, Qixingqiao HLM and other small communities were not properly intercepted, and there were many rain and sewage mixed into the river pipeline. A large number of black and brown floating objects were floating on the river surface, which made the site smell pungent. The surrounding people responded strongly, On site sampling and testing found that its dissolved oxygen was 0.6 mg/L, indicating a mild black odor. In September 2022, the "Dongting Qingbo" Office of Yiyang City assigned the problem of black and odorous water in the channel on the side of Templo Mayor Lane in Nanxian County, and the relevant responsible units immediately rectified it. In April 2023, the warning film "Environmental Protection Rectification Always on the Road" of Yiyang City revealed the problem of black and odorous water in the channel. The inspector found that the water surface of the channel was covered with green duckweeds, and the water was black. Through on-site sampling and monitoring, it was found that the dissolved oxygen was 0.680 mg/l, Ammonia nitrogen is 20.7 milligrams per liter, which still belongs to severe black odor. In 2022, the special supervision of "Dongting Qingbo" in Yiyang City made an unannounced visit to deal with the black and odorous problem of the water body in the near first middle school of Shijihu Road, Yuanjiang City. This supervision found that the water body in this section was turbid in color, and the on-site sampling monitoring showed that the ammonia nitrogen concentration was 7.87 mg/L, still belonging to mild black and odorous.

（3） Inadequate rectification of sewage treatment and interception pipeline network

In order to achieve the standard of black and odorous water body treatment, Yiyang City formulated and issued the Implementation Plan of Yiyang City's Urban Black and odorous Water Body Treatment Campaign (hereinafter referred to as the Plan) on December 25, 2019, proposing five major measures, including source control and interception, endogenous treatment, establishment of a long-term mechanism, strengthening supervision and inspection, and specific safeguard measures. The inspector found that Yiyang City has lagged behind in promoting some of the contents specified in the Plan, which clearly requires that the problem of mixed connection of rainwater and sewage pipelines in urban built-up areas should be investigated by the end of September 2020, and the reconstruction should be gradually completed in combination with road quality improvement, sewage interception works and rainwater and sewage diversion in the area. However, currently only some areas such as Longling Industrial Park and High tech Zone have been renovated, while other areas have not yet been inspected and renovated. The 'Plan' clearly requires that all drainage permits for drainage households in urban built-up areas be completed by the end of 2020, and post certification supervision should be strengthened. However, Yiyang has not yet completed the above drainage permit handling work, and only issued a notice of correction for the rain and sewage mixing of one drainage household, so the supervision is insufficient. At present, the total length of the pipe network in the central city of Yiyang is 1151.13 kilometers, and the combined pipe network is 315.03 kilometers, accounting for more than a quarter. Since the 14th Five Year Plan, the total number of sewage pipe networks (completed or under construction) renovated in the city has only been 27.868 kilometers, and the pollution control and interception of the pipe network have been slow and ineffective.

3、 Cause analysis

Relevant districts and counties (cities) in Yiyang City do not know enough about the importance of water environment protection, the main responsibility for the treatment of black and odorous water bodies is not implemented, the black and odorous water bodies are not comprehensively, systematically and thoroughly treated from the perspective of source control and interception, and the long-term mechanism is not implemented after the problem is cancelled, leading to a rebound. The housing and construction departments of Yiyang City failed to coordinate the tasks specified in the Action Plan for Water Pollution Prevention and Control and the rectification of the "looking back" feedback problems of the provincial environmental protection supervision in 2018 and the provincial ecological environmental protection supervision in 2020. There was a lack of follow-up management in the later period, and the long-term system and mechanism were not perfect.

In response to the above issues, the inspection team will further investigate and verify, and carry out follow-up inspection work in accordance with relevant requirements and procedures. In case of dereliction of duty in the supervision and rectification work, Yiyang City will be urged to investigate and deal with it in accordance with laws and regulations.