Minimizing Infrastructure Deterioration

 Scott H. Paul, P.E., President

CorrTech, Inc.

77 West Main St

Hopkinton, MA 01748

508 435-0090

Originally presented at the:

119th Annual Conference

New England Water Works Association

Royal Sonesta Hotel

Cambridge, MA

September 17-20, 2000

ABSTRACT

This presentation identifies the causes of corrosion and methods of mitigation as they apply to water storage, transmission and distribution infrastructure.  Both submerged and buried corrosion exposures will be discussed.

The 55,000 water systems in the United States will be faced with many issues relative to infrastructure installation, upgrading and replacement.  Of concern is system integrity, to minimize service disruptions and the risk of water supply contamination.  The majority of service interruptions of large infrastructure can be attributed to corrosion.  Costs associated with system infrastructure are very high, and monies need to be expended prudently.  Understanding infrastructure condition and corrosion exposure is an important part of the overall Infrastructure Master Plan for existing and new systems.

MINIMIZING INFRASTRUCTURE DETERIORATION-MASTER PLAN

In the management of large infrastructure, the cost of corrosion prevention is relatively small when compared to the cost of total replacement or substantial rehabilitation.  Therefore the goal is to prevent failures from occurring, extending the service life of the capital plant.  This approach is preferred to a program of failure management, where service interruption, product contamination, losses to personal property and personal injury are all possibilities.  Although there are other infrastructure failure mechanisms, corrosion is a major factor in the deterioration and failure of water industry metallic infrastructure. 

It has been reported by the National Bureau of Standards that the annual cost of corrosion in the United States is on the order of $70 billion per year.  This cost can be attributed to loss of useful life of equipment, cost of corrosion mitigation, litigation and downtime.  Considering the substantial mileage of water pipe, number of storage tanks and the variety of metallic components in the water treatment plant, a considerable percentage of that annual cost is borne by the water utility industry. 

In addition, it has been reported by the American Water Works Association that the cost to water utilities over the next 20-years will be approximately $325 billion to upgrade and replace losses caused primarily by corrosion.  It is clear that many of the decisions as to how these monies should be allocated need to be based on a clear understanding of the corrosion exposure that exists on existing and new infrastructure.  Critical systems cannot be installed and forgotten, but instead must be constantly managed to provide lower life cycle costs and ensure that undesirable failures do not interrupt operation. 

Much of the existing infrastructure, installed as early as the late 1800’s, is in good condition and with modification could be upgraded to provide many more years of reliable service.  There are several corrosion engineering studies and analyses that can be employed to define the condition of the infrastructure of concern.  By understanding the current infrastructure condition, defining the corrosion mechanisms, delineating corrosion rates and understanding the environment corrosivity, projected life calculations can then be made.  These studies are then utilized to develop infrastructure life extension options for economic analysis.

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