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Li Z.,Carbon Capture Scientific | Buchberger S.G.,University of Cincinnati | Clark R.M.,Environmental Engineering and Public Health Consultant | Jeffrey Yang Y.,U.S. Environmental Protection Agency | Swertfeger J.,Greater Cincinnati Water Works
Journal - American Water Works Association | Year: 2012

Full-scale field measurement and rapid small-scale column test data from the Greater Cincinnati (Ohio) Water Works (GCWW) were used to calibrate and investigate the application of the logistic model for simulating breakthrough of total organic carbon (TOC) in granular activated carbon (GAC) contactors. The logistic model parameters were estimated using a nonlinear regression algorithm. The calibrated logistic model was validated using data from multiple GAC contactors operating in parallel at the GCWW Richard Miller Treatment Plant. This facility has experienced large seasonal variations in flow rate and TOC influent concentration. Proper estimation of logistic model parameters depends on the run-time length of the GAC breakthrough data set. A critical minimum runtime threshold must be achieved to produce reliable parameter estimates. A properly calibrated logistic model provides an effective tool for accurately simulating the blended TOC concentrations in the GAC contactor effluent at a municipal drinking water treatment plant. © 2012 American Water Works Association.


Clark R.M.,Environmental Engineering and Public Health Consultant | Thurnau R.C.,Eastern Research Group
14th Water Distribution Systems Analysis Conference 2012, WDSA 2012 | Year: 2012

Condition Assessment (CA) modeling is drawing increasing interest as a technique that can assist in managing drinking water infrastructure. This paper presents a model based on the use of a Cox Proportional Hazard (PH) approach modified by shared frailty and applies it to the drinking water network of the Laramie Water Utility (located in Laramie, Wyoming (USA) ). Using this model a cost/benefit analysis incorporating the Inspection Value Method (IVM), is used to assist in making improved repair, replacement and rehabilitation decisions for drinking water distribution system pipes. A separate analysis was conducted using a national data base model focused on prestressed concrete cylinder pipe (PCCP). Various currently available inspection technologies are presented and discussed. Copyright © (2012) by Engineers Australia.


Clark R.M.,Environmental Engineering and Public Health Consultant | Thurnau R.C.,Eastern Research Group
Frontiers of Earth Science | Year: 2011

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. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.


Deininger R.A.,University of Michigan | Lee J.,Ohio State University | Clark R.M.,Environmental Engineering and Public Health Consultant
Frontiers of Earth Science | Year: 2011

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. This technique has a great deal of potential for application in situations in which a water system has been compromised. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.


Li Z.,Carbon Capture Scientific Ltd Liability Company | Li Z.,University of Cincinnati | Clark R.M.,Environmental Engineering and Public Health Consultant | Buchberger S.G.,University of Cincinnati | Jeffrey Yang Y.,U.S. Environmental Protection Agency
Journal of Environmental Engineering (United States) | Year: 2014

This paper describes a technique for evaluating the impact of climate change on drinking water treatment operations and for applying engineering principles to minimize those impacts. The U.S. Environmental Protection Agency (USEPA) Water Treatment Plant model was modified, validated, and applied to a case study based on the Greater Cincinnati Water Works' Richard Miller treatment plant to provide quantitative measures of these impacts. Multivariate Monte Carlo experiments were executed to simulate and track performance of the Miller plant subject to nine jointly distributed source water quality parameters under both current and potential future hydrologic conditions. Results from the case study indicate a risk that finished water may exceed critical total organic carbon (TOC) levels, leading to potential violations of disinfection by-product regulations under plausible future scenarios. The future risk, however, can be managed with operational adjustments at the water treatment plant, such as increasing the frequency of granular activated carbon reactivation. Utility costs associated with the operation adjustments were expressed as cost curves. The approach presented in this paper can be useful for evaluating climate change impacts and for planning infrastructure and operational adaptation. © 2014 American Society of Civil Engineers.


Li Z.,University of Cincinnati | Buchberger S.G.,University of Cincinnati | Clark R.M.,Environmental Engineering and Public Health Consultant | Yang Y.J.,U.S. Environmental Protection Agency
Water Distribution Systems Analysis 2010 - Proceedings of the 12th International Conference, WDSA 2010 | Year: 2012

Climate change may adversely affect source water quality and therefore impact the design and operation of drinking water treatment plants. Many water utilities are concerned about the effect of climate change on the operation and sustainability of their drinking water treatment infrastructure. The USEPA Water Resources Adaptation Program (WRAP) has studied this effect through a water treatment plant simulation model (WTP model) and demonstrated that the risk of violating total organic carbon (TOC) guidelines in finished water under potential future scenarios at the Richard Miller water treatment plant in Cincinnati could be managed by modifying the operation of the existing granular activated carbon (GAC) unit. In this initial work, TOC removal at the GAC unit was controlled by adjusting the GAC reactivation period. In reality, however, TOC removal can be also affected by site-specific factors such as contact time, type of GAC, and structure of contactors. As a follow-up investigation, this paper demonstrates how site-specific treatment studies can be used to customize simulation algorithms for GAC units at municipal water treatment utilities. Results from simulation of the Richard Miller treatment plant demonstrate that customized models offer a measurable improvement over the general statistical approach used in the existing WTP model. These findings can help utilities define practical plans to control TOC removal at GAC units and adapt to changes in source water quality. © 2012 ASCE.


Clark R.M.,Environmental Engineering and Public Health Consultant | Li Z.,University of Cincinnati | Buchberger S.G.,University of Cincinnati
Frontiers of Earth Science | Year: 2011

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. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.


Clark R.M.,Environmental Engineering and Public Health Consultant
World Environmental and Water Resources Congress 2015: Floods, Droughts, and Ecosystems - Proceedings of the 2015 World Environmental and Water Resources Congress | Year: 2015

Even though drinking water hydraulic and water quality models are a recent development in the water industry, they have become widely used by both large and small utilities. The U.S. Environmental Protection Agency (US EPA) played a major role in the development of hydraulic/water quality modeling techniques and they have become embedded in the US Safe Drinking Water Act (SDWA). A key factor in encouraging the development of hydraulic/water quality modeling was the decision by the US EPA that drinking water standards promulgated under the SDWA of 1974 would apply at the consumers tap. The SDWA also requires that the cost of meeting standards at the tap must be considered. After passage of the SDWA (1974), and based on mandates contained in the Act, the US EPA began a systematic research effort that carefully examined the factors affecting the cost and quality of treated drinking water as it is transported through a pipe network. Research included theoretical analysis, mathematical modeling and field studies and lasted more than 20 years eventually leading to the development of EPANET. An early decision made during the development of EPANET was to make it open-source software and as a consequence, it has provided the basis for many research projects and studies including numerous graduate dissertations throughout the world. It has also provided the foundation for most of the proprietary models in use by the industry today including the quasi-public model PipeLine Net. In Fiscal year 2013 the US EPA recorded over 66,000 downloads of the software. © 2015 ASCE.


Clark R.M.,Environmental Engineering and Public Health Consultant
Frontiers of Earth Science | Year: 2011

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. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.


Clark R.M.,Environmental Engineering and Public Health Consultant
Water and Environment Journal | Year: 2015

Hydraulic and water quality models have become widely used to understand both the hydraulic behaviour, and the fate and transport of contaminants in drinking water distribution systems. Research conducted by the United States (US) Environmental Protection Agency (EPA) played a major role in the development and application of hydraulic/water quality modelling in the United States and throughout the world. Eventually this research led to the development of EPANET, an integrated hydraulic/water quality model, and had a major influence on the implementation of the United States Safe Drinking Water Act (SDWA). The modelling research conducted by the US EPA has helped many drinking water utilities throughout the world alleviate public health threats due to the deterioration of water quality in drinking water networks. The US EPA has provided over 100 000 downloads of the EPANET software over the last 2 years. © 2015 CIWEM.

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