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If you've got an opinion about something you've read in PUBLIC WORKS, send your comments to edit@pwmag.com. Include your name, title, and organization/company. Letters may be edited for clarity and length.

In response to “Chemical reactions,” (June 2010, page 25):

As a corrosion engineer for the Illinois DOT, I see frequent occurrences of corrosion of truck bodies, undercarriage, and brakes, as well as plow wear/bolt breakage. So I found Paul Abelson's article on the development of crevice corrosion in various truck components interesting and informative — it contained many recommendations that I forwarded to my transportation department's districts. These problems are particularly severe for trucks that plow snow or dispense salt or brine.

— Christopher Hahin, MetE, CorrE, PE, engineer of structural materials & bridge investigations, Illinois DOT


In response to “And the award goes to … ” editorial (March 2011, page 9):

“Rain Dance” (August 2010, page 54), written by Michael Fielding, was a great job of reporting and condensing into common language the difficulties related to managing point vs. nonpoint sources of water pollution. Though I don't deal with stormwater directly, the article crystallized the concern we have about ever-increasing regulation.

The article prompted me to do a Web search, where I found a master's thesis that had been posted in the late 1990s. Though more informative, the author used 100 pages to provide insights similar to those PUBLIC WORKS provided inn three pages (including pictures) — and your magazine's article was as much more compelling.

— Dennis Wright, right, city engineer,ineer, City of West Linn, n, Ore.


In response to “Something fishy with failures?” Ideas & Opinions article (March 2011, page 23):

This article's questionable statements, missing information, and erroneous conclusions warrant a response.

Author Patricia Galloway paints a picture that the fish hatchery in Jasper, Texas, was poorly designed and that it was ideally suited for reinforced concrete pipe (RCP). While I agree the original installation was poorly designed, the statement that the project was ideally suited for RCP is purely conjecture. Had the original installation used standard Class III reinforced concrete pipe, it would have failed at 7 to 8 feet of cover, according to literature published by the American Concrete Pipe Association (ACPA).

Second, Galloway seems to indicate that concrete pipe performance is not dependent on backfill materials. This is simply not true. Proper backfill material and compaction is critical for the success of rigid pipe as well as flexible pipe installations, an aspect clearly articulated in the ACPA's design manual.

Third, Galloway misleads the reader by concluding that this particular application was not suited for high-density polyethylene (HDPE) pipe and was “perfectly acceptable for an RCP CP system.” Surprisingly, she fails to mention that the reinstallation ultimately required a Class V concrete pipe — the most stout and robust class of concrete pipe made — and installed with select backfill material. The real issue wasn't the pipe material, but the installation and design conditions. No pipe would be suitable for the project given the original installation specifications. Galloway does nothing to educate your readers regarding the importance of pipe system design, including proper trench construction and backfill materials, which is really at the crux of this failure.

Finally, Galloway implies that the HDPE pipe warranties are different than RCP warranties. Once again, this isn't true. Our HDPE pipe-manufacturing members warrant their pipe against structural defects, as do RCP manufacturers. Successful systems of both pipe types require attention to the installation, the backfill materials, and the design. As such, all pipe warranties must take installation and design into account.

Galloway's article lacks technical integrity and is more of a scare tactic directed squarely to design engineers. We are confident that the majority of your readers can see through her artifice.

— A. (Tony) Radoszewski, executive director, Plastics Pipe Institute


In response to “Another year of higher prices” (March 16, 2011 e-newsletter editorial):

Though very informative, your article's usefulness depends on my understanding of paint formulation types, costs, and characteristics. I'm not sure I correctly distinguished among them.

Also, how does the durability of alkyd-based latex compare to other formulations?

— Dave Hutson, PE, senior engineer, Portland Bureau of Transportation, Maintenance Operations, Oregon

Editor's note: We asked our source for this particular article — Phil Phillips (phillips@chemarkconsulting.net), managing director of The Chemark Consulting Group Inc. — to devise a table to clear up any confusion other readers may have had:

To answer the last question on durability: Yes, alkyd-based latex is tougher than acrylics (takes more traffic and keeps on looking good).

The acrylic-based latex resin is based on Methyl Methacrylate (MMA), an oil-sourced raw material that's in short supply — so costs are going up. Its dry time is slower than anything solvent-based in normal application temperatures from 50° to 80° F. Acrylic-based latex (water-based systems) in temperatures below this range will take much longer than solvent-based, but will bake out faster in temperatures above this range.

Water-based acrylic latex resins cost less than most types of solvent- or water-based resins.

Alkyd-based latex is water-based. Depending on the source, it ranges from 95 cents to $1.45/lb. Reichhold is in the 95 cent to $1.05/lb range while others are higher. Dry time can be as fast as acrylic-based latex, but slower than solvent-based alkyds.















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