Water Safety Concepts - Standards and Guidelines

from each individual contaminant across all potential pathways. Acceptable risk levels are commonly given by national standards (see Section 3.4).

all hazards over all parts (=system analysis) and check through periodic monitoring, if crit-ical points (=health-based targets) are exceeded or not. The HACCP aims to determine as early as possible a negative alteration of physical, chemical, technical or hygienic parame-ters within the complete chain of investigation. Thus, the water safety plan challenges water managers to know, control and monitor all possible hazards within the complete supply sys-tem from source to tap.

The water safety plan framework complies with the multi-barrier concept. Therefore, haz-ards across the three barriers, water resources, the water treatment plant and the distribu-tion network, are identified (=system assessment). The monitoring of control measures (e.g., data collection related to the health-based targets) help to guarantee safe drinking water and a proper system operation. Management plans based on qualitative risk ranking should be used to mitigate risk, whether it does not comply with the health-based targets. The wa-ter safety plan is embedded into independent and periodic surveillance of the system. The desired result is that public health is not endangered, and the degree of goal fulfillment is communicated and published to the population. This strengthens the confidence of cus-tomers into the supplied drinking water as required by the Bonn Charter (IWA et al., 2004).

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Figure 3.4.: Methodology of risk-based and process-oriented management according to Bonn Charter (IWA et al., 2004).

3.4.2. Risk Assessment and Management by US EPA Standards

In the United States of America the protection of drinking water is regulated by the safe drinking water act amendment (Tiemann, 2010) with the overarching goal of human-health protection. More than70regulations have been promulgated by the US EPA only between 1976 and 2002. These standards define Maximum Concentration Levels (MCL) for chemical and microbial contamination to avoid adverse health effects by consumption and exposure

of drinking water. The individual states are free to choose their own health standards, but have to be at least as strong as the ones proposed by the US EPA (2009).

Risk assessment in the field of environmental engineering started in the US with the RAGS Manual (US EPA, 1989). Risk assessment has been performed for Superfund sites. Later, several State regulatory agencies required risk assessment also for non-Superfund sites. In the90’ies, the American Society for Testing and Materials (ASTM) published the Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites (ASTM RBCA Standard) that is based on the RAGS Manual. The goal of this standard was to remediate only those contaminated sites, which pose the greatest risk to the groundwater. As early as 2000, the US EPA considered the assessment of health effects due to chemical mixtures (US EPA, 2000). In 2007, the US EPA published a standard regarding cumulative health risk assessment of multiple chemicals, exposures and effects updating the 2003 standard. The evaluation of the cumulative impact involves all sources, contaminants and their interac-tion, media, exposure routes, vulnerability of individuals, and is measured via the hazard index. These multi-chemical exposures are ubiquitous, being present in soil, ambient air or drinking water.

Another framework for analyzing and managing risk, especially in the light of terrorist at-tacks, is RAMCAP: Risk Analysis and Management for Critical Asset Protection (ASME, 2006). The goal of this guideline and risk management methodology is to protect national infrastructures at risk, especially in the course of9/11. A seven-step process provides the fundamental basis to understand and manage risk from terrorism. The American Water Works Association (AWWA) has adopted the RAMCAP framework to assess the risk of as-set and system failure. The American Water Works Association emphasizes the need to con-sider the worst reasonable case scenarios in risk management, which makes risk assessment either risky or expensive.

3.4.3. German Risk Standards

In Germany, there exists a long tradition of water protection. Thus, many national stan-dards to protect drinking water resources exist. Most regulations are promulgated by the German Association of Gas and Water (DVGW), such as the standards for technical safety management (DVGW, 2000) and wellhead delineation (DVGW, 2006). Maximum concen-tration levels are set by the federal ministry of health and are promulgated in the drinking water directive (TrinkwV, 2001). Regarding risk assessment and management, only two standards exist. These two standards address risk-based and process-oriented management of hazards during normal operations (DVGW standard W1001, 2009) and during critical sit-uations (DVGW standard W1002, 2009), which are defined as crisis. In this context, a crisis is defined as situations where the water supply company alone cannot cope with the cur-rently faced situation. The procedure in a crisis is strongly based on a military background, implying that one crisis leader has all the executive and legislative power.

In the remainder of this thesis, I only consider theDVGW standard W1001(2009) for risk man-agement during normal operation. Supply safety under normal operation is guaranteed, if the water company is running properly. This is fulfilled by keeping health-related issues (e.g., TrinkwV, 2001), esthetic aspects (DIN, 2000) and technical requirements (e.g.,

work-ing standards promulgated by the DVGW), such as sufficient pipe pressure and amount of water. These requirements are only achieved, if the involved stakeholders, government, wa-ter companies and consumers work jointly together. In order to guarantee supply safety, a methodology is proposed to deal with hazards and compare their relevance related to their potential to alter the drinking water quality. All parts of the supply chain (resource protec-tion, water producprotec-tion, treatment, storage and distribution to the consumer) are considered to assess and evaluate hazards. Here, hazard is defined as a potential biological, chemical, physical or radiological detriment within the supply system. Thus, the guideline comple-ments the required end-product control regulations by the technical safety management standard DVGW (2000) and is in line with the water safety plans of the WHO (Davison et al., 2005).

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order to systematically identify, assess, evaluate and control risk sources. In the first step, the guideline suggests to describe the supply system with all potential hazards that have the potential to lead to detrimental water quality and quantity. In the next step, qualita-tive or semi-quantitaqualita-tive risk assessment approaches are proposed to assess the damage potential of these hazards, the probability of hazard failure, and to estimate the resulting risk. To illustrate the results and rank hazards, the international standard approach using a 3×3or5×5risk matrix is suggested. The third step evaluates the suitability of risk mitiga-tion alternatives, fulfilling the technical regulamitiga-tions published by the DVGW. Risk treatment methods that are not included in any of the technical guidelines of the DVGW are validated concerning their effectiveness, e.g., monitoring parameters before and after installation. The monitoring of water parameters and the frequency of sampling is essential to verify that risk

of known hazards is controlled. Finally, all observations, findings, data measured and meth-ods used throughout the risk analysis need to be documented and periodically repeated to constantly improve supply safety. The presented outline of the DVGW W1001 is in line with the ISO standard.

3.4.4. Wellhead Protection by Delineation

The delineation of wellhead protection zones is commonly performed in many countries world-wide. The common goal is to prevent drinking water from being contaminated by bacteria or other contaminants such as chlorinated solvent, pesticides and petroleum prod-ucts. One example are the US EPA regulations (e.g., US EPA, 1993) that are, in turn, in accordance with the safe drinking water act amendment (Tiemann, 2010). The safe drinking water act requires from the individual States to develop source protection programs and in specific focus on two major hazards: microbial or chemical/radiological contaminants. The US EPA regulation suggests the delineation of time-related capture zones in line with the multi-barrier approach. The Wakerton, Ontario, Canada, tragedy in2000with several dead people and thousands of people getting ill from bacteriologically contaminated drinking water was a wake-up call across Canada to enforce regulations and improve province-wide time-related capture zones, following the multi-barrier concept (O’Connor, 2002). Here, I will focus on the German national standard DVGW (2006) as the relevant standard in this thesis for wellhead delineation.

The national standard DVGW (2006) splits the drinking water catchment into three zones.

The inner zone closest to the production wells is called zone1. The restriction level within this area is very high, abandoning almost all activities besides mowing the grass. In gen-eral, the land of zone 1is owned by the supply company. The second zone is defined by an intrinsic 50-day advective travel time to the well, considering peak arrival time. The standard provides several methods to assess the travel-time-based delineation. Intensive agriculture and industrial activities are not allowed per se within these areas, to avoid mi-crobial arrival at the production well. The third zone is split into two categories with only minor restrictions to land-use activities. The regulation of activities within wellhead protec-tion zones is regulated alone by local authorities and, in more severe cases, in conjuncprotec-tion with the provincial (regional) ministry. Also, the delineation of wellhead protection zones is enforced by the ministry and not by the water company. It is also the ministry that decides, if a well capture zone deserves protection or not.

Furthermore, the standard (DVGW, 2006) provides a list of potential hazards split into seven categories, such as traffic and transport, residential area, agriculture, industry, waste wa-ter and others. In accordance to these categories, Haakh et al. (2013) developed a semi-quantitative risk assessment approach in collaboration with stakeholders of the DVGW re-search project

”Risk assessment in drinking water catchments“. This approach is further discussed in Section 3.5.