Rolf A. Deininger

Protecting the Nation's Critical Infrastructure: The Vulnerability of U.S. Water Supply Systems

Terrorism in the United States was not considered a serious threat until the second half of the 1990s. However, recent attacks both at home and abroad have forced government planners to consider the possibility that critical elements of the U.S. infrastructure might in fact be vulnerable to terrorism. The potential for chemical or biological contamination of water supply systems exists along with the possibility that such systems might be sabotaged. This article reviews the threat of biological and chemical compounds in relation to the characteristics of water supply systems. Vulnerability of such systems to terrorist attacks is examined, as well as possible physical and chemical countermeasures that could be applied. A case study is presented of an accidental contamination event that illustrates the difficulty of tracking such events in a drinking water system. It can be concluded that municipal water supplies are vulnerable. However, appropriate physical planning of such systems, including contingency back-up with separate water lines for emergencies, coupled with proactive monitoring, will significantly increase security in the face of possible terrorist attacks.

A Water Quality Index — Crashing the Psychological Barrier

Use of this somewhat bombastic title stems from our desire to draw critical attention to a process of decision making that in practice has been more of an art than a science. At issue is the long standing need for a uniform method for measuring water quality - a “yardstick” with units that are simple, stable, consistent, and reproducible — and an unambiguous method for communicating this information to everyone concerned.

Generalization of White's Method of Successive Approximations to Periodic Markovian Decision Processes

The difficulty in solving a Markovian decision problem with a large number of states by Howards policy-iteration method is that one has to solve a large system of simultaneous linear equations. Procedures developed by D. J. White and J. MacQueen, which avoid this difficulty, have been widely used to handle large-scale Markovian decision problems. This paper extends these algorithms to the case where the Markovian decision process is periodic. Proofs of the convergence of these new algorithms are sketched. Some computational experiences based on the modeling of the Great Lakes regulation systems are also given.

Drinking water and cancer mortality

The problem of understanding the possible adverse health effects of organic chemical contaminants in drinking water is not new, but national concern has intensified in recent years. Despite this concern and regulatory efforts, no definitive relationship has been established between organic contamination and human health effects. This paper examines some of the sources of possible organic contamination, current knowledge concerning human health effects and the most current epidemiological data. Historic CCE and CAE data were extracted from STORET and used in regression analyses. Age-adjusted 20-year average cancer mortality rates were regressed against the sum of CAE and CCE for those counties with STORET monitoring data of their drinking water source. Results indicate statistically highly significant relationships particularly for GI-urinary tract cancers.

Modelling regional waste water treatment systems

The economies of scale of waste water treatment plants favor regional systems. This paper presents a mathematical formulation of this problem, and suggests an algorithm for solution. Several case examples are shown.

Survival of Bacteria After Ozonation

Abstract The change of the bacterial population after each water treatment process was examined in a full-scale water treatment plant that uses ozone as a primary disinfectant. The fluctuation of heterotrophic bacterial number along the water treatment processes was determined. After ozonation, the bacterial number decreased to 13 CFU/mL. The surviving bacteria after each water treatment process were identified to genus or species level. The significant finding was the predominance of double-layered gram-positives (75%) among the surviving bacteria after ozonation. It included Mycobacterium spp., Bacillus spp., Corynebacterium spp., and Micrococcus spp. On the other hand, the dominance of gram-negatives was observed in most other water samples but each treatment process exerted different selection on dominant bacterial groups. The proportion of opportunistic pathogens was the lowest in the ozonated water.

Rapid Assessment of Microbial Hazards in Metalworking Fluids

Industries that use metalworking fluids require a test method that can rapidly estimate the total number of bacteria. Such a test method would improve the ability to manage the metal working fluid by allowing near real−time decision making. The ability to manage the fluid more consistently and make critical decisions as they arise would reduce occupational exposures to contaminated metalworking fluid and likely result in fewer worker complaints and/or work stoppages. In this study, a filtration−based rapid adenosine triphosphate bioluminescence assay, which takes less than 10 min to perform, was evaluated as a test method for estimating total bacteria populations in metalworking fluid. This evaluation used two types of metalworking fluid (soluble and semisynthetic) that were inoculated usingPseudomonas aeruginosa and spoiled metalworking fluid. Daily parallel testing was completed on metalworking fluid samples using the rapid adenosine triphosphate assay and the standard plate count methods. Daily test results were evaluated by calculating r 2 values using statistical correlation and regression procedures for each fluid type. Study result sindicate the rapid adenosine triphosphate assay is strongly correlated to the standard plate count method for soluble and semisynthetic fluids, producing results of r 2 = 0.74 and r 2 = 0.89, respectively.

Sabotage of Public Water Supply Systems

During times of war, there is always talk of threats cf terrorism against public water supplies. In the recent Gulf War, a number of utilities in the U.S. stepped up their security measures by guarding their treatment plants and distribution systems (AWWA, 1991). Special security procedures were in place during the Olympic Games in both Los Angeles and Atlanta.

A MICROCOMPUTER-INTERFACED CONTINUOUS FLOW TOXICITY TEST SYSTEM

Abstract While continuous-flow tests for toxicity evaluation are preferable over static tests, their use has been limited due to problems associated with their operation. Fluctuations in toxicant concentrations during exposure periods requires frequent analyses and represent a drawback in conventional diluter systems. To reduce toxicant fluctuations and to maintain suitable water quality during long-term test periods, a low cost microcomputer-interfaced monitoring system (MIMS) was installed on a Benoit type serial diluter. The system monitored flow rates of test solutions and measured a number of water quality parameters. The MIMS system provided up-to-date information on whether the test was progressing well and indicated when diluter maintenance was needed. The MIMS interfaced diluter system performed well in long-term continuous-flow tests with minimal disruption and eliminated experimental failure.

An interactive data management system for river water quality data

Abstract Water quality data banks are needed to document the status and trends of water pollution in a country. Examples of such systems are the STORET system in the U.S., the NAQUADAT system in Canada and the EIS system in Scandinavia. All of these systems require trained personnel to help in the formulation of the inquiry and the actual querying of the system. By contrast, what is described in this paper is an on-line, interactive data management and analysis system which allows the user the direct search, update, retrieval and analysis of the data from a computer terminal. The user addresses the system in a high level language closely resembling English and has complete control over building, updating and querying the individual data banks. Almost all statistical operations can be performed on the data starting from histograms, distributions, correlations to regression, discriminant, component and spectral analysis. Commands for producing camera-ready graphs on graphic terminals are available. The system is implemented on The University of Michigan Computer System and can be accessed through local telephone numbers in more than 100 cities in the U.S. and Canada and from the major European capitals via the TELENET system. The operation of the system is illustrated on a small sample data base on the Ohio river provided by the Ohio River Sanitation Commission (ORSANCO).