 Proceedings of Engineering and Technology Innovation , vol. 4, 2016, pp. 25 - 27 25 Proactive Management of Water Quality in Aquifer Storage Transfer and Recovery Sang-Il Lee, Hyon Wook Ji * Department of Civil and Environmental Engineering, Dongguk University, Seoul, South Korea. Received 18 February 2016; received in revised form 16 March 2016; accept ed 09 April 2016 Abstract This paper reports the status of an ongoing effo rt to ensure the quality of water produced at an Aquife r Storage Transfe r and Recovery (AST R) site in South Ko rea. AST R is one of the managed aquifer recha rge techn iques in which water is intentiona lly re charged to suit - able aqu ife rs for subsequent recovery. Surface water injected to an aquifer is converted into water of drin kab le qua lity by natu ral p rocess. In an AST R pro ject being developed in the densely populated de lta area of the Nakdong River basin, a ne w fra me work is be ing imp le - mented in wh ich water safety is addressed through the analysis and control of bio logica l, chemica l, and physica l ha zards fro m intake , pretreat ment, in jection and re covery, to d istri- bution and consumption of wate r. The task is done by the incorporation of Ha zard Analysis and Critica l Control Po int (HA CCP) to the AST R process. Originated fro m the food in - dustry, HA CCP identifies, evaluates, and co n - trols ha za rds to ensure the safety of th e product. Princ iples o f HA CCP we re applied to the AST R water p roduction system. Ha zard ana l- ysis revealed that most haza rdous events were due to the chemica ls transported in the basin. Risk assessment was conducted to identify the sources of che micals wh ich pose a potentia l threat to the wate r quality o f the AST R site . Such in formation will be va luable fo r the pro - active manage ment of che mica ls at the basin scale. Crit ica l control po ints (CCP) were d e - termined by the decision tree method, and crit ica l limits fo r wate r qua lity pa ra mete rs at CCPs were established subsequently . Keywor ds : aquifer storage transfer and recov- ery, HACCP, water quality, Nak- dong River, risk analysis 1. Introduction The Nakdong River , one of the four ma jor rivers in South Korea, is a main source of drinking water for mo re than ten million people. The water quality of The Na kdong River has been deteriorated due to both routine emission fro m cit ies and water pollution incidents [1]. According to a consumer survey in South Korea, 32.5% of respondents do not drink tap water because they have concerns about raw water quality [2]. Hence, there e xist imminent needs to improve drinking water quality and to protect raw water fro m pollution. To s atisfy these needs, two technologies are combined. First, Aquifer Storage Transfer and Recovery (ASTR) can be an alternative for quality im- provement in drinking water production [3]. ASTR is a method to store surface water in an aquifer through an injection well and to recover the water through an extraction well (Fig. 1). A pilot plant is being developed in the delta of the Nakdong River. Fig. 1 The process of drin king water supply using ASTR Second, Ha zard Analysis and Crit ical Co n- trol Point (HA CCP) is incorporated to ensure the water quality throughout the drinking water production process . HACCP is a tool to assess hazards and establish control systems to guar- antee the safety of food. Recently, World Health Organization (WHO) and many countries in- cluding U.S and Australia tend to adopt HACCP * Corresponding aut hor, Email: mousehw@naver.com Proceedings of Engineering and Technology Innovation , vol. 4, 2016, pp. 25 - 27 26 Copyright © TAETI for drinking water supply [4]. 2. Method The pilot study strictly fo llo ws the seven principles of HACCP [4]. First, a co mprehensive list was created of all microbia l, che mical and physical haza rds having the potential to cause harm [5]. A unique feature of this study is that we conducted the risk analysis to obtain info rmation for proactive manage ment of chemical haza rds in the entire basin. Potential risk can be e x- pressed as a function of the amount of t ransfers, distance, and toxicity as in Eq. 1. Potential risk =f(amount of chemical transfers, distance, toxicity) (1) Since the data of the a mount of transfers were insuffic ient for probabilistic ana lysis, synthetic data were generated by using the sto- chastic method. The generated data we re fitted to probability distributions. The potential risk for each c ity can be calculated and the most risky city becomes the target of special monitoring and manage ment to reduce chemical risk posing on the ASTR site. ‘Determin ing the critica l control points ’ is a key issue in HACCP [5]. CCP is a ma jor process to prevent and treat hazards efficiently. CCPs were determined by the decision tree method in which four questions were asked [6]. Then, critical limits for water quality param- eters at CCP were established based on the liter- ature and the legal regulations . Critical limits can be considered as the minimu m baseline for which hazards do not affect human health. 3. Results and Discussion Total 114 haza rdous events were identified fro m the entire process in producing drinking water using AST R. Various chemical, physical and microbio logical ha zards re lated to those hazardous events exist. Out of 114, nine ma jor hazardous events were particularly screened ; seven out of nine events originated fro m the catchment area. A ll these events involved chemical haza rds. If the haza rdous chemica l events occurring in the basin could be properly managed, the risk to the drinking water supply can be significantly reduced. The potential risk for 42 c ities in the basin was analyzed for the period of 2001 to 2012. As for the probability density function needed for synthetic data generation, the Weibull d istribu- tion (2-para meter) was the most frequently chosen, while the norma l and the Gu mbe l dis- tribution followed. The city of Yangsan turned out to be the most potentially-risky city in terms of chemical ha zards . It means that if a plan to mitigate che mical ha zards in the Na kdong River basin is to be imp le mented, Yangsan should be the first city. Ten processes for drinking water supply using ASTR were subject to the decision tree analysis . CCPs turned out to be catchment area , pre-treat ment, in jection, treat ment, storage of treated water, and distribution to consumers . The process not classified as CCP is Po int of Attention (POA) [7]. A lthough its importance is relative ly lowe r, proper attention should be given to POAs. Critica l limits fo r water quality para meters at CCPs we re developed to monitor and control microbial, chemical and physical hazards. 4. Conclusions Integration of ASTR and HA CCP was im- ple mented to ensure water quality on drin king water supply in a densely populated area. Nat- ural filt ration of low-quality surface water in an aquifer can enhance public trust in water supply among consumers. In addition, the applicat ion of HACCP will reduce the risk and eventually improve the negative recognition on drin king water. Although the pilot study is in its early phase, its influence to the water supply system in this region cannot be neglected. Acknowledgement This research was supported by Basic Sci- ence Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2015R1D1A1A 09060690). References [1] J. K. Lee , T. O Kim, and Y. J. Jung, “Analysis of domestic water pollution ac- cident and response management (in Ko- rean),” Journal o f Wetlands Research, vo l. 15, no. 4, pp. 529-534, 2013. Proceedings of Engineering and Technology Innovation , vol. 4, 2016, pp. 25 - 27 27 Copyright © TAETI [2] S. H. Cho, Y. J. Lee , and H. B. Yoon, “Korean’s perception and attitudes regard- ing their tap water (in Korean),” Korean Public Hea lth Research, vol. 32, no. 2, pp. 130-140, 2006. [3] P. Dillon, “ Future manage ment of aquife r recharge,” Hydrogeology journal, vol. 13, pp. 313-316, 2005. [4] A. Tavasolifar, B. Bina, M. M. A min, A. Ebrah imi, and M. 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