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Protective Coating for Wastewater Facility Concrete Surfaces — Best Practices Coatings can be an efficient and cost-effective technical solution for protecting and renewing sanitary sewer tanks, pipelines and appurtenances. Asset management principles and practices require wastewater utilities to look beyond the initial cost and focus more on long-term solutions and lower life-cycle costs. Premature failures of coatings have generated much concern regarding true life-cycle costs. Concrete coating systems for wastewater service must typically withstand immersion, harsh chemicals, abrasion, low pH and other challenging conditions. Premature coating failure is significantly higher with concrete than with steel, for example, due to several additional variables including moisture content, surface strength, surface irregularity, alkalinity, composition and porosity, which results in a difficult surface to effectively coat and protect. Other factors include surface preparation and coating system mixing, application and curing practices, to name only a few. Some of the most common concrete coating system defects and failure mechanisms in wastewater applications are: • Osmotic blistering • Pinholes and voids • Peeling These failures or defects will typically lead to premature concrete damage, compromising structure integrity and personnel safety and necessitating costly repair and premature infrastructure replacement. Many concrete coating products for wastewater service exist in the marketplace and new products are entering the market frequently. This paper provides a review of the importance of product and process validation and presents recommendations and lessons learned in specifying, applying and utilizing these products over the past 20 years. By Jeff Maxcy and Tom Iseley Product Evaluation and Validation Product evaluation and validation is not a new concept, and has been demonstrated to be an important factor in achieving success. It provides the benefit of using materials that have already proven to be effective in similar applications. Owner representatives and consulting engineers have for many years realized the importance of reviewing new products and processes. Most of the larger utilities with support from consultants have developed product review committees (PRCs). However, small- to medium-size utilities tend to have no formal process. Even for utilities with PRCs, the review, validation and acceptance/rejection tend to vary significantly from agency to agency. Often this process is time-consuming, awkward, inconsistent, subject to political influence and expensive. This wide variance in how decisions are made to accept/reject products and processes results in major challenges and expense for the technical solution providers. In 2009, the City of Indianapolis and the Construction Engineering Management Technology (CEMT) program at the Purdue School of Engineering and Technology at IUPUI entered into a collaborative agreement that resulted in development of a 10-step new product review process. To date, more than 15 products have been evaluated through this innovative process at no expense to the City. The technology providers pay a fee. This program has been very successful. During 2010, both Fort Wayne, Ind., and Zionsville, Ind., have entered into similar agreements with the university. Due to the strong interest in the new product review process from utilities and consultants across the nation, a new program will be launched to provide access to all new product review reports on a subscription basis. The nonprofit Institute of Product Validation (IPV) (www.institutepv.com) has been formed to manage the national program. Any utility or industry representative can subscribe to the IPV services and access the new product 36 Water Utility Infrastructure Management November/December 2011
eports. Future reviews, validation and report development will be done utilizing an academic alliance. The academic alliance will begin with six universities throughout North America. The alliance is expected to continue to expand. The reviews will rotate among the universities and three universities will conduct peer reviews. Product Selection Concrete coating system selection, as well as specification writing, is challenging because of the number of variables involved. These include geographic location, the concrete mix design, admixtures, placement and finishing techniques. Concrete is also comparatively weak in tension, has an irregular surface, contains moisture and is easily contaminated. The first, and perhaps most important, step should be to develop an accurate understanding of the conditions and requirements unique to each project. After the requirements are known, system options can be evaluated to make informed decisions. It is important when selecting a product to simply read what is written under the general description on the manufacturer’s data sheet. The material should be specifically designed for wastewater exposure. While there are many materials that will stand up well, the manufacturer and applicator should be able to demonstrate successful experience and history with the selected products in similar applications. Manufacturers who might not be familiar with the unique corrosive environment within sanitary sewers will try to convince the engineer to specify materials that were not necessarily intended for sanitary sewer use. The products may hold up to the service, but their use without a proven history introduces an undesirable element of risk of major damage. Whenever available, the experience and lessons learned from installations within the utility’s system should be fully considered. When specifying a replacement system, an accurate understanding of any past failures and performance limitations is key to ensuring future success and improved performance. The specifier should also consider soliciting input from other wastewater utilities that can confirm performance of candidate systems, or provide additional case histories, lessons learned or other experiences that could be considered for the project. Another way to check likely performance of candidate concrete coating systems is to check if the material passed tests performed under severe service conditions by John Redner and Associates for the County Sanitation Districts of Los Angeles from 1983 to 2004. This publication is readily available and lists 39 products that have passed the test. However, even if the proposed products will hold up to laboratory tests, it does not mean that they will be able to be successfully installed in the field. Some of these products are difficult to work with and require extremely skilled applicators. Also, the inevitable variables associated with each unique job may have a detrimental effect on their performance. It is interesting to note that this product evaluation program was developed by a wastewater utility. Initially, it was developed to meet the needs and answer questions for this particular utility; however, it soon became recognized as a standard throughout the wastewater industry. The rapid recognition and acceptance of this program demonstrates the need for product performance validation information. Coating System Specifications In some cases, it might be appropriate to specify performance criteria instead of specific products. This approach is thought to shift some of the risk to the contracted installer, but has the downside that the applicator may not be the ideal technical person to select the best materials and processes to produce the desired performance. In most cases and particularly for critical or complex applications, these decisions are best made by an experienced and qualified protective coating specialist. It can be difficult to determine which standards should be included in a concrete coating system specification. Manufacturers often have performance criteria shown on their data sheets that are not necessarily important to the application. The system specifier should understand which tests are relevant, as well as what constitutes a passing test. For instance, a specification may list performance criteria from one manufacturer’s data sheet with a high value for a certain ASTM standard, but not necessarily be pertinent to the application. This value will essentially disallow some manufacturers that would otherwise perform well for the application. Always use the proper industry standards from NACE, ASTM, SSPC and ICRI when specifying, installing and testing coatings in a sewer system. Field Conditions Less-than-ideal conditions should be expected and can be especially difficult to overcome. For example, in existing sewers, the coating applicator will typically have to NEW WATER RESOURCE! The Future of Water Discover how municipalities, water utilities, industries and individuals can resolve challenges facing the water industry to make a better future. Topics Covered Include: * Water quality & shortages * Population & economic growth * Energy, climate & pollution * Water use, transportation & storage Author: Steve Maxwell Hardbound/243 pages *Shipping and handling not included. Selling price subject to change without notice. For more information visit www.uimonline.com/info Price: $34.99* Price: $34.99* resource center benjaminmedia.com/book-store 330-467-7588 November/December 2011 Water Utility Infrastructure Management 37
Page 2 and 3: For more information visit www.uimo
Page 4 and 5: CONTENTS November/december 2011 COV
Page 6 and 7: 36 34 Teaming Up for Water Delivery
Page 8 and 9: CONTRIBUTORS Pamela A. Malone serve
Page 10 and 11: FROM THE PUBLISHER’S DESK CWC and
Page 12 and 13: NEWS WEFTEC 2011 Attracts Strong Cr
Page 14 and 15: NEWS MEETINGS U.S. Conference of Ma
Page 16 and 17: NEWS LEAK DETECTION Wachs Water Ser
Page 18 and 19: W A S H I N G T O N R E P O R T Mob
Page 20: For more information visit www.uimo
Page 23 and 24: the Wadsworth Mutual Water Company
Page 25 and 26: Water Utility Infrastructure Manage
Page 27 and 28: Background Utility: Douglasville-Do
Page 29 and 30: screen. The ratio of productive, sc
Page 31 and 32: There are common issues across util
Page 33 and 34: P3 Implementation in Canada Public-
Page 35: Tampa Bay Water, Veolia Water North
Page 39 and 40: The consequences of failure usually
Page 41 and 42: PROFESSIONAL INDEX Company Website
Page 43 and 44: Uniting the Trenchless World Presen

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