Risk Assessment of Water Intakes in South-Eastern Poland in Relation to the who requirements for Water Safety Plans
Discussion of Results and Assessment of the Need to Establish or Adapt Water
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| 4. Discussion of Results and Assessment of the Need to Establish or Adapt Water
Protection Zones The water quality of rivers, which are the source of water supply, is threatened by adverse events related to the discharge of untreated municipal wastewater (Event 6) and, to a lesser extent, by agriculture (Event 4). This is due to the fact that some of the areas located in the catchment area of these rivers still do not have sewage systems (sewage systems in communes is at the level of approximately 70%), which, in the absence of the control of invoices for waste disposal, means that residents often discharge sewage into the ground or a ditch. According to administrative units, eutrophication caused by pollution from municipal sources is the most significant threat to a high-quality water status in the Podkarpackie Province in Poland. For this reason, the ammonium nitrogen content is a very important indicator of water quality. The content of individual nitrogen ionic forms present in the water (ammonium NH 4 + , nitrate NO 3 – and nitrite NO 2 ) and the assessment of their variability over time, along with correlation with the data on land use in the vicinity of the intake, allows for an approximate assessment of the time and possible origin of the pollutants. The ammonium ion found in water intended for human consumption may come from anthropogenic pollutants entering the intake (mainly surface intakes). The source of threats may be a situation where water pollution (sewage, natural and artificial fertilizers, rainwater runoff and leachate from landfills) causes microbiological contamination of the water or penetration of the water by toxic chemicals. The ammonium Resources 2021, 10, 105 12 of 15 ion is not the cause of the danger here, but it does signal risk. In the winter season, when both vegetation and nitrification are inhibited, the values of ammonium ion concentrations show an upward trend (Event 10). The greatest threats are periodic increases in turbidity and water blooms causing, among others, the necessity for the frequent rinsing of filters (Event 9). Very high turbidity (even 3000 NTU) is often associated with the occurrence of flood water flows (Event 7). In the analyzed time period (10 years), water intake was continuous, and the water treatment plant worked continuously, pumping water to the water supply network in compliance with the regulation from the Polish Minister of Health on 7 December 2017 on the quality of water intended for human consumption. Maintaining the suitability of the water treatment plant, however, required heavy involvement from the operators and a strict control of the treatment process (mainly filter rinsing). The analysis of the current crisis situations and the method of dealing with them prove that the technology of the water treatment process in the analyzed systems meets the criteria set for them, and is matched to the changing hydrological conditions of the river and a wide range of raw water parameters. When it comes to catastrophic events caused by a potential failure of the sewage treatment plant (Event 2), the risk is very diverse, due to the fact that the efficiency of the sewage treatment plant and its distance from the water intake have a decisive influence on the level of risk. The greatest risk is caused by a failure of the wastewater treatment plant located within the indirect protection zone of the water intake, approximately 4.8 km from Intake A, and the failure of the planned wastewater treatment plant, which was to be located at a distance of approximately 7 km from Intake C. The probability of such an event occurring is small, but the potential consequences require the introduction of a tight security system in anticipation of it occurring. After the major failure of a collector sending sewage to the “Czajka” wastewater treatment plant in Warsaw in August 2019, the General Inspectorate for Environmental Protection in Poland called on municipalities to check their procedures in the event of a serious accident in wastewater treatment plants. It should be noted that the water supply companies are not responsible for the technical condition of the installations in external sewage treatment plants, however their improper functioning (inconsistent with the water permit) or failure significantly impedes the maintenance of the appropriate quality of water supplied to consumers. The harmful effects of third parties (Event 8) can potentially cause many diseases, but it should be emphasized that the poisonous substance is significantly diluted in raw water. The results of the risk analysis are the presentation of proposals for remedial measures and proposals for the extent of the indirect protection zones for water intakes A–D. The proposed extent of the indirect protection zones for Intake A, Intake B and Intake C is shown on the map in Figure 4 . This is the area for which the risk analysis was carried out, i.e., the water intake catchment area covering an area of 12-h water inflow. However, the conducted risk analysis did not show any significant threats to the water intake for Intake B. In connection with the above, combined with the fact that the entire area covered by the study includes a specially protected natural area (i.e., Landscape Park) and that there is a lack of large sanitary wastewater treatment plants and industrial plants posing potential threats, there is no need to establish an indirect protection zone for the water intake. The analyzed water supply systems are equipped with the necessary security measures related to the intake of surface water. The risk assessment of threats to the water intakes did not reveal any significant threat to water consumers. Resources 2021, 10, 105 13 of 15 Resources 2021, 10, x FOR PEER REVIEW 15 of 17 tải về 1.26 Mb. Chia sẻ với bạn bè của bạn:
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