It has become generally accepted that water quality can deteriorate in a distribution system through microbiological and chemical reactions in the bulk phase and/or at the pipe wall. The most serious aspect of water quality deterioration in a network is the loss of the disinfectant residual that can weaken the barrier against microbial contamination. Studies have suggested that one factor contributing to the loss of disinfectant residuals is the reaction between bulk phase disinfectants and pipe wall material. Free chlorine loss in corroded metal and PVC pipes, subject to changes in velocity, was assessed during an experiment conducted under controlled conditions in a specially constructed pipe loop located at the US Environmental Protection Agency’s (EPA’s) Test and Evaluation (T&E) Facility in Cincinnati, Ohio (USA). These studies demonstrated that in older unlined metal pipes, the loss of chlorine residual increases with velocity but that wall demand in PVC was negligible.

Natural disasters can be devastating to local water supplies affecting millions of people. Disaster recovery plans and water industry collaboration during emergencies protect consumers from contaminated drinking water supplies and help facilitate the repair of public water systems. Prior to an event, utilities and municipalities can use “What if”? scenarios to develop emergency operation, response, and recovery plans designed to reduce the severity of damage and destruction. Government agencies including the EPA are planning ahead to provide temporary supplies of potable water and small drinking water treatment technologies to communities as an integral part of emergency response activities that will ensure clean and safe drinking water.

The purpose of this project was to: 1) describe the effects of climate change in the Arctic and its impact on circulation, 2) describe hindcast data used in the Ocean Energy Management, Regulation and Enforcement (BOEMRE) Oil Spill Risk Analysis (OSRA) model, 3) evaluate alternatives such as using forecast results in the OSRA model, and 4) recommend future studies. Effects of climate change on winds, sea ice, ocean circulation and river discharge in the Arctic and impacts on surface circulation can be evaluated only through a series of specially designed numerical experiments using high-resolution coupled ice-ocean models to elucidate the sensitivity of the models to various parameterizations or forcings. The results of these experiments will suggest what mechanisms are most important in controlling model response and guide inferences on how OSRA may respond to different climate change scenarios. Climatological change in the Arctic could lead to drastic alterations of wind, sea ice cover and concentration, and surface current fields all of which would influence hypothetical oil spill trajectories. Because of the pace at which conditions are changing, BOEMRE needs to assess whether forecast ice/ocean model results might contain useful information for the purposes of calculating hypothetical oil spill trajectories.

It is anticipated that global climate change will adversely impact source water quality in many areas of the United States and will therefore, potentially, impact the design and operation of current and future water treatment systems. The USEPA has initiated an effort called the Water Resources Adaptation Program (WRAP) which is intended to develop tools and techniques that can assess the impact of global climate change on urban drinking water and wastewater infrastructure. A three step approach for assessing climate change impacts on water treatment operation and design is being persude in this effort. The first step is the stochastic characterization of source water quality, the second step is the application of the USEPA Water Treatment Plant model and the third step is the application of cost algorithms to provide a metric that can be used to assess the coat impact of climate change. A model has been validated using data collected from Cincinnati’s Richard Miller Water Treatment Plant for the USEPA Information Collection Rule (ICR) database. An analysis of the water treatment processes in response to assumed perturbations in raw water quality identified TOC, pH, and bromide as the three most important parameters affecting performance of the Miller WTP. The Miller Plant was simulated using the EPA WTP model to examine the impact of these parameters on selected regulated water quality parameters. Uncertainty in influent water quality was analyzed to estimate the risk of violating drinking water maximum contaminant levels (MCLs). Water quality changes in the Ohio River were projected for 2050 using Monte Carlo simulation and the WTP model was used to evaluate the effects of water quality changes on design and operation. Results indicate that the existing Miller WTP might not meet Safe Drinking Water Act MCL requirements for certain extreme future conditions. However, it was found that the risk of MCL violations under future conditions could be controlled by enhancing existing WTP design and operation or by process retrofitting and modification.

The purpose of this paper is to explore the nature of water-related disasters, look at the trends in water-related disasters, categorize water-related disasters in several dimensions, provide insights on the impacts of such disasters and discuss the predictability of disasters. Disasters may be succinctly defined as natural or human events, usually unexpected, that result in significant impacts in terms of a variety of metrics. Metrics for evaluating the impacts of disasters include economic damage, environmental damage, fatalities, reconstruction cost, aesthetic damage, disruption of normal activities, destruction of irreplaceable objects, and long-term or permanent loss of species. Disasters may be categorized in terms of causes (natural events, human induced, or a combination). Water-related disasters may be further categorized as floods, storms, waves, slides, droughts, epidemics, contamination and climate change. The temporal and spatial scale of water-related disasters vary by many orders of magnitude ranging from seconds to centuries and from a few square kilometers to the entire earth.

Water systems are inherently vulnerable to physical, chemical and biologic threats that might compromise a systems’ ability to reliably deliver safe water. The ability of a water supply to provide water to its customers can be compromised by destroying or disrupting key physical elements of the water system. However, contamination is generally viewed as the most serious potential terrorist threat to water systems. Chemical or biologic agents could spread throughout a distribution system and result in sickness or death among the consumers and for some agents the presence of the contaminant might not be known until emergency rooms report an increase in patients with a particular set of symptoms. Even without serious health impacts, just the knowledge that a water system had been breached could seriously undermine consumer confidence in public water supplies. Therefore, the ability to rapidly detect contamination, especially microbiological contamination, is highly desirable. The authors summarize water contamination case studies and discuss a technique for identifying microbiological contamination based on ATP bioluminescence. This assay allows an estimation of bacterial populations within minutes and can be applied using a local platform. Previous ATP-based methods requires one hour, one liter of water, and has a sensitivity of 100000 cells for detection. The improved method discussed here is 100 times more sensitive, requires one-hundredth of the sample volume, and is over 10 times faster than standard method. T\his technique has a great deal of potential for application in situations in which a water system has been compromised.

In the last years many interesting studies were devoted to the development of technologies and methodologies for the protection of water supply systems against intentional attacks. However the application to real systems is still limited for different economical and technical reasons. The Water Engineering Laboratory (L.I.A.) of University of Cassino (Italy) was involved in two research projects financed by the European Commission in the framework of the European Programme for Critical Infrastructure Protection (E.P.C.I.P.). Both projects, developed in partnership with a large Italian Water Company, have the common objective of providing guidelines for enhancing security in water supply systems respect to the intentional contamination risk. The final product is represented by the arrangement of a general procedure for protection systems design of water networks. In the paper the procedure is described through the application to two real water systems, characterized by different size and behavior.

Condition assessment (CA) Modeling is drawing increasing interest as a technique that can assist in managing drinking water infrastructure. This paper develops a model based on the application of a Cox proportional hazard (PH)/shared frailty model and applies it to evaluating the risk of failure in drinking water networks using data from the Laramie Water Utility (located in Laramie, Wyoming, USA). Using the risk model a cost/benefit analysis incorporating the inspection value method (IVM), is used to assist in making improved repair, replacement and rehabilitation decisions for selected drinking water distribution system pipes. A separate model is developed to predict failures in prestressed concrete cylinder pipe (PCCP). Various currently available inspection technologies are presented and discussed.

Multiple organizations over the years have collected and analyzed data on cyber attacks and they all agree on one conclusion: cyber attacks are real and can cause significant damages. This paper presents some recent statistics on cyber attacks and resulting damages. Water and wastewater utilities must adopt countermeasures to prevent or minimize the damage in case of such attacks.

Many unique challenges are faced by the water and wastewater industry while selecting and implementing security countermeasures; the key challenges are: 1) the increasing interconnection of their business and control system networks, 2) large variation of proprietary industrial control equipment utilized, 3) multitude of cross-sector cyber-security standards, and 4) the differences in the equipment vendor’s approaches to meet these security standards. The utilities can meet these challenges by voluntarily selecting and adopting security standards, conducting a gap analysis, performing vulnerability/risk analysis, and undertaking countermeasures that best meets their security and organizational requirements.

Utilities should optimally utilize their limited resources to prepare and implement necessary programs that are designed to increase cyber-security over the years. Implementing cyber security does not necessarily have to be expensive, substantial improvements can be accomplished through policy, procedure, training and awareness. Utilities can also get creative and allocate more funding through annual budgets and reduce dependence upon capital improvement programs to achieve improvements in cyber-security.

The presented spatial risk assessment method allows for managing critical network infrastructure in urban areas under abnormal and future conditions caused e.g., by terrorist attacks, infrastructure deterioration or climate change. For the spatial risk assessment, vulnerability maps for critical network infrastructure are merged with hazard maps for an interfering process. Vulnerability maps are generated using a spatial sensitivity analysis of network transport models to evaluate performance decrease under investigated thread scenarios. Thereby parameters are varied according to the specific impact of a particular threat scenario. Hazard maps are generated with a geographical information system using raster data of the same threat scenario derived from structured interviews and cluster analysis of events in the past. The application of the spatial risk assessment is exemplified by means of a case study for a water supply system, but the principal concept is applicable likewise to other critical network infrastructure. The aim of the approach is to help decision makers in choosing zones for preventive measures.

Conventional water infrastructure in urban environments is based on the centralized approach. This approach consists of building pipe network that provides potable water to consumers and drainage network that transport wastewater and stormwater runoff away from population centers. However, as illustrated in this article, centralized water infrastructures are not sustainable over a long period of time for a variety of reasons. This article presents the concept of a holistic approach for sustainable water management that incorporates decentralized water infrastructures into water management system design in urban environments. Decentralized water infrastructures are small to medium-scale systems that use and/or reuse local sources of water such as captured rainwater, stormwater runoff and wastewater. The holistic approach considers these waters as a valuable resource not to be wasted but utilized. This article briefly introduces various types of decentralized water infrastructures appropriate for urban settings. This article focuses on the effectiveness of rooftop rainwater harvesting systems as a decentralized water infrastructure and as a critical component of developing a holistic and sustainable water infrastructure in urban environments. Despite widespread use of rainwater harvesting systems, limited information has been published on its effectiveness for sustainable management of water resources and urban water infrastructures. This article, discusses multi-dimensional benefits of rainwater harvesting systems for sustainable management of water resources and its role as a critical component of decentralized water infrastructures in urban environments.

Combined with the basic characteristics of Suzhou plain river network, two modules are established, one of which is the hydrodynamic module using the water level node method involving gate operation, while the other is the water quality module based on the principle of WASP5 (water quality analysis simulation program5). These two modules were coupled and verified by the monitoring data of Suzhou River network. The results showed that calculation errors of NH4+-N and DO for the model were in the ranges of –15%—13% and –18%—16%, respectively. Despite of the deviations between the monitoring data and simulation result, the calculation accuracy of the model conforms to the practical engineering requirement. Therefore, the proposed coupling model may be useful for water quality simulation and assessment for river network under tidal influences.

The US Army Corps of Engineers has a mission to conduct a wide array of programs in the arenas of water resources, including coastal protection. Coastal projects must be evaluated according to sound economic principles, and considerations of risk assessment and sea level change must be included in the analysis. Breakwaters are typically nearshore structures designed to reduce wave action in the lee of the structure, resulting in calmer waters within the protected area, with attendant benefits in terms of usability by navigation interests, shoreline protection, reduction of wave runup and onshore flooding, and protection of navigation channels from sedimentation and wave action. A common method of breakwater construction is the rubble mound breakwater, constructed in a trapezoidal cross section with gradually increasing stone sizes from the core out. Rubble mound breakwaters are subject to degradation from storms, particularly for antiquated designs with under-sized stones insufficient to protect against intense wave energy. Storm waves dislodge the stones, resulting in lowering of crest height and associated protective capability for wave reduction. This behavior happens over a long period of time, so a lifecycle model (that can analyze the damage progression over a period of years) is appropriate. Because storms are highly variable, a model that can support risk analysis is also needed. Economic impacts are determined by the nature of the wave climate in the protected area, and by the nature of the protected assets. Monte Carlo simulation (MCS) modeling that incorporates engineering and economic impacts is a worthwhile method for handling the many complexities involved in real world problems. The Corps has developed and utilized a number of MCS models to compare project alternatives in terms of their costs and benefits. This paper describes one such model, Coastal Structure simulation (CSsim) that has been developed specifically for planning level analysis of breakwaters.