Since the aqueducts that served early Rome to the present day, man has continued to develop new technologies for the delivery of drinking water. As one system aged and eventually failed, it was replaced by another, employing the latest construction materials and techniques of the time. The Twentieth Century saw the greatest expansion of civil projects in the history of the United States. As the century neared its end, the challenge posed by the nation’s aging infrastructure became evident. Numerous studies were completed with the purpose of delineating the scope of the impending national crisis. These studies focused not only on highways and bridges but also on drinking water and wastewater systems. EPA’s Drinking Water Infrastructure Needs Survey determined the national capital expenditure need over the next 20 years is approximately $150 billion. Given this incredible need water system managers must provide a replacement strategy in order to maintain a good standard of living. The cost of replacing water systems is too large, however, to replace all of the substandard systems. Managers must set priorities. Using a risk assessment approach enables system managers to base their decisions upon quantitative information rather than the empirical knowledge that “more needs to be done.” This project will provide a model that determines the risk associated with various replacement strategies, taking into account local conditions and infrastructure histories.

BACKGROUND

Much has been made, in recent years, of the potential crisis facing the nation due to our aging infrastructure. This concern is easily understood by the public as they travel along highways constructed over 50 years ago and cross bridges built by their grandparents. In contrast, however, the deteriorating condition of the nation’s underground infrastructure has not been appreciated to the same degree. This is primarily because water mains and sewer mains tend to be “out of sight and out of mind.” The American Society of Civil Engineers adds:

“Although America spends billions on infrastructure each year, drinking water faces an annual shortfall of at least $11 billion to replace aging facilities that are near the end of their useful life and to comply with existing and future federal water regulations.”—ASCE, 2005

As a consequence of the perceived spending disparity, the EPA (2001), conducted, in 1999, the Drinking Water Infrastructure Needs Survey (DWINS), published by EPA in 2001. This effort revealed that transmission and distribution systems accounted for 56 percent of the capital expenditure need for the next 20 years. The other infrastructure categories: treatment, finished water storage and source of supply make up the balance of the capital need at 25, 12 and 6 percent respectively. The total capital need over the next 20 years is, as determined by the DWINS study, $150 billion, of which, about $85 billion is allocated to transmission and distribution systems.

EPA, in September 2002, issued, The Clean Water and Drinking Water Infrastructure Gap Analysis. This study was intended to follow up on the conclusions of DWINS and to illustrate the gap in capital and operations & maintenance spending if current spending levels are continued into the future. This study reinforced the need, from a national perspective, to acknowledge the risks posed by under-funding the future needs for infrastructure renewal. G. Tracy Mehan, III, EPA’s Assistant Administrator for Water, states,

“The analysis suggests that a large gap will result if the challenge posed by an aging infrastructure network—a significant portion of which is beginning to reach the end of its useful life—is ignored.”

These studies are critical for bringing awareness to the overall problem and helping legislators deal with funding allocation issues. They also prompt the local water system managers to ask, “How does this affect me and my system? Am I budgeting enough for water main replacement?”

Many studies by organizations like the American Waterworks Association (AWWA) and the US Environmental Protection Agency (EPA) have provided evidence describing the scope of the national problem, but few examples are presented, at the water system level, for quantitatively establishing pipeline replacement schedules. Few water system managers would argue the fact that more needs to be done in renewing their respective transmission and distribution systems. It is difficult for them, however, to present a defendable program without the necessary tools to describe the level of risk that each alternative schedule presents. The goal of this project is to provide those tools.

PROJECT PROPOSAL

OBJECTIVE

The purpose of the project is to provide a methodology water system managers can use for optimizing main replacement strategies for their distribution systems. This method will utilize a risk assessment approach for establishing replacement schedules for aging drinking water transmission and distribution mains.

THE RISK ASSESSMENT MODEL

The critical question is how to determine the best strategy for maintaining control of water pipeline maintenance costs as the deteriorating condition of the pipes progressively worsens with time. Several pipeline replacement strategies, using different annual replacement footages, will be analyzed using historical leak data from ABC Utility Company. The proposed method will project the future deterioration of the water mains and the resultant failure rates. This information plus the maintenance costs associated with the water main repairs are used to determine the risk posed by each strategy. The analysis provides several key outputs for each plan, the annual capital cost and the projected maintenance cost by year for the life of the overall project (for instance, the replacement of all remaining metallic pipe with diameters of 4-inch and smaller). The manager will then have the necessary information for balancing the capital investment cost versus the expected trend in annual pipeline maintenance expenditures.

It is anticipated the model will demonstrate the level at which maintenance costs will rise in the near term as the result of low annual capital expenditures. On the other hand, it should also quantify the more rapid decline in maintenance cost resulting from higher capital spending.

The project work plan is broken into several phases.

Review the background of water distribution and the evolution of pipeline materials:

Investigate the history of central drinking water systems, as presented by Haestad et al. (2003) and Walski (2006), from the ancient aqueduct systems of Rome to the modern transmission and distribution systems. Pipeline materials have gone through a multitude of material types from hollowed-out logs to clay pipe to present-day PVC and ductile iron pipe.

Research the growth of distribution systems in the United States

Much of the growth of drinking water distribution systems in the United States occurred during the economic expansion following World War II. Walski (2006) and the Cast Iron Pipe Soil Pipe Institute (1994) describe with this growth, and the continued evolution of pipeline materials, which resulted in numerous material types being employed during the Twentieth Century. As an example, galvanized iron pipe was popularly used for low demand, residential areas from 1900 through the early 1960’s. This pipeline material is the focus of many water main replacement plans.

Investigate the declining condition of the nation’s infrastructure systems, including water distribution

EPA, (2002) and (2005), conducted studies to evaluate the condition of water systems and the risk faced if water system operators do not take a much more aggressive approach to the replacement of their aging pipelines. The American Society of Civil Engineers (2005) also provides valuable insight into the state of America’s underground water infrastructure systems and the level of effort being spent to address the declining condition of these systems.

Contact engineering and/or asset managers of other water systems to determine the methods used for establishing main replacement plans

The engineering and asset managers from several Pacific Northwest water systems will be contacted to determine the methods they use for determining priorities and replacement schedules for their aging pipelines. These include the water systems serving:

--Salem, OR

--Seattle, WA

--Portland, OR

--Bellevue, WA

--King County, WA

In addition the following ABC Utility Company systems will be contacted:

--ABC Utility Company New York

--ABC Utility Company New Jersey

--ABC Utility Company Delaware

--ABC Utility Company Pennsylvania

--ABC Utility Company Arkansas

Previous information from several of these systems indicates varying levels of development for their asset management plans. Their input will be valuable in both confirming the techniques proposed in this project and adjusting the approach.

The following data will be requested for each water system:

Number of customers served
Total footage of distribution system
What is the status of your asset management program

Fully developed
Personnel and systems such as GIS and Maintenance Management Systems committed to the program development
Just getting started

What data is collected during leak repair activities (include all that apply)

Total leaks for system only
Leaks by size of pipe
Leaks by material
Leaks by year of installation
Cause of leak (i.e., corrosion, poor installation, construction activities….)

How is the data recorded

On spread sheets
In a database
Other, please specify

Is leak data used in planning main replacement activities?

If so, how is the data used, please describe.

Present case studies of pipelines operated by ABC Utility Company

ABC Utility Company keeps leak records which will be analyzed and used as the basis for developing the model and validating the leak projection concepts presented by Shamir and Howard (1979). A significant level of information has been developed regarding the maintenance history of ABC Utility Company’s transmission and distribution system. The GIS system is also relatively mature, providing a high level of detail regarding the distribution of water mains by size, material and date of installation. This provides the capability for many different and revealing analyses, such as leaks by size, by material, by year of installation and various combinations of the three.

With this information, it is possible to determine the risk (Rausand 2004) associated with replacement schedules based upon a wide spectrum of characteristics. EPA (2002) and (2005) bases the need for replacement primarily on age alone. A broader view is likely more relevant as all pipe materials do not deteriorate at the same rate, nor do all diameters of the same material deteriorate the same.

Two case studies, based upon ABC Utility Company’s small metallic mains (4-inch and smaller) and larger metallic mains, will be conducted with the objective of demonstrating the utility of the risk assessment model as a decision making tool. Both of these pipeline groups represent high maintenance materials and, as a result, should provide valuable data for analysis.

Provide recommendations for data collection needed for the risk assessment model

The usefulness of the risk assessment model is only as good as the data it is based upon. As a result, accurate leak data collection is critical for ongoing asset management programs, as described by the AWWA Research Foundation (2005). Data entry forms must be carefully designed to ensure reliability of the information added to the database. It is essential for efficient and accurate data entry, and future data retrieval, that data base record forms have rigid rules which require conformance before the record can be saved. For instance, these rules would not allow a 1935 installation date for PVC pipe or 2-inch diameter for Asbestos Cement pipe.

A sample record form will be developed, including rules for data entry as described above. This form will have utility for leaks and customer service level calls. It is important that customer service levels be considered in the design of the data entry forms. This will enable the correlation of discolored water and pressure complaints from particular street addresses with the water main delivering service to the property.

References:

Haestad Methods, Inc., (2003), “Advanced Water Distribution Modeling and Management”, Haestad Press.

United States Environmental Protection Agency, (2002), “The Clean Water and Drinking Water Infrastructure Gap Analysis”, September 2002.

United States Environmental Protection Agency, (2001), “Drinking Water Infrastructure Needs Survey”, February 2001.

Shamir, Uri and Howard, Charles D.D. (1979), “An Analytical Approach to Scheduling Pipe Replacement”, American Water Works Journal, May 1979, pages 248-258.

Rausand, Marvin, (2004), “System Reliability Theory (2^nd Edition)”, Wiley-Interscience.

Cast Iron Soil Pipe Institute, (1994), “Cast Iron Soil Pipe and Fittings Handbook”, Cast Iron Soil Pipe Institute.

AWWA Research Foundation, (2005), “Managing the Future: Trends in Drinking Water”, Drinking Water Research, January/February 2005, pages 2-8.

United State Environmental Protection Agency – Office of Research and Development, (2005), “White Paper on Improvement of Structural Integrity Monitoring for Drinking Water Mains”, March 2005.

American Water Works Association, Hughes, D.M., Technical Editor, (2002), “Assessing the Future: Water Utility Infrastructure Management”, American Water Works Association.

Matichich, M, Allen, J., and Allen , R., (2006), “Asset Management Planning and Reporting Options for Water Utilities”, American Water Works Journal, January 2006, pages 80-87.

Stahr Jr., Richard W., (2006), “Asset Management – One Size Does Not Fit All”, Opflow, January 2006, pages 10-12, American Water Works Association.

Walski, Thomas M., (2006), “A History of Water Distribution”, American Water Works Journal, March 2006, pages 110-121.

Davis, Paul and Burn, Stewart, (2006), “Long-Term Performance Prediction for Plastic Water Pipes – PVC and PE”, Drinking Water Research, January/February 2006, pages 1-4, American Water Works Association.

Wood, Andrew and Lence, Barbara J., (2006), “Assessment of Water Main Break Data for Asset Management”, American Water Works Journal, July 2006, pages 77-86.

American Society of Civil Engineers (ASCE), (2005), “Infrastructure Report Card 2005”, http://www.asce.org/reportcard/2005/index.cfm.

Work Schedule:

November 13 – Deliver Draft Project Proposal

November 27 – Review Project Proposal

December 8 – Deliver edited version of Project Proposal for review

March 1 – Make final edits and sign

March 31 Complete analyses and draft report, deliver for initial review and comment

April 15 – Deliver revised project for review and comment

April 30– Project presentation and final exam

May 5 – Submit paper in final form

Moscow, ID 83844

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