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Compliance with stormwater regulations on the third-runway project at the Seattle-Tacoma International Airport in Washington proved to be complex and challenging. Photo: Hach Co.

In the November issue you have an article about the Seattle-Tacoma Airport third runway stormwater treatment project (page 46). Was the article paid advertising or a free informative article on the Chitosan-Enhanced Sand Filtration (CESF) systems at the third runway project? If the article is to be informative, it ignored the heart of why this project has been so successful.

Based on my experience, I believe a more in-depth view of CESF system operation should have been presented. From reading the article, one might presume that these systems are virtually trouble-free. To become proficient in CESF system operation takes a great deal of training. Operating multiple high-flow systems is even more demanding.

My concern, based on experience and reading your article, is that these systems are portrayed as trouble-free. To emphasize the success of this developing technology and not address the complex operational requirements and skills necessary to achieve these goals seems misleading. The facts given in the article concerning water quality and discharge are correct, however.

When properly installed and operated by qualified operators, CESF systems have achieved great success. Natural Site Solutions (NSS), the developer of CESF systems, and Stormwater LLC have worked hard in developing and improving operational procedures, data collection, system monitoring, water quality testing, reporting procedures, and training.

The success of any CESF system depends on the depth of the operator's training and time spent on the job—and not just the equipment used. Regardless of equipment, there always will be system failures. During a heavy rain event it is essential to quickly diagnose any problems that may arise due to turbidity, pH, equipment malfunction, or monitoring failure—and to bring the system back online without violating water quality standards. Whether a company is treating 100 or 1000 gallons per minute, the need to maintain constant crystal-clear water discharge always will require the services of a highly trained and devoted water quality treatment team.

NSS and Stormwater LLC undertook this project and worked together with a handshake and common goal “to develop and operate an environmentally safe and efficient stormwater treatment system that would quickly clarify, test, and discharge clean stormwater that would surpass Department of Ecology (DOE) standards.”

The success of CESF systems lies primarily in the hands of highly trained and dedicated system operators, and not just in the reliability of pumps, plumbing, or data-monitoring equipment that have proven time and time again to fail. Anyone thinking of using CESF systems first needs to understand the operating procedures that may be specific to their particular soil conditions to avoid discharging water that does not meet DOE standards.

— Jim Thorwart, CPESC, president, Stormwater LLC, Tacoma, Wash.