Achieving Performance Improvement in Tennessee’s Ground Water Protection Program

The Division of Ground Water Protection's goal of ensuring that the ground waters of Tennessee are maintained in a safe and usable condition is heavily dependent on the proper application of underground septic systems for wastewater disposal in areas lacking wastewater treatment plants. Ensuring that installed underground septic tanks are properly manufactured with respect to size and quality of construction is a key element in improving performance of these systems. Two basic approaches to septic tank quality are available to the Division of Ground Water Protection. The approach currently used attempts to ensure quality by 100% inspection of tanks at the site after they are set within the ground, with rejection of any improperly sized or poorly manufactured tanks. An alternate approach relies primarily on certification of tank manufacturing processes by an independent certifying body to ensure that quality is “built in” to the tanks, with random plant inspections serving to monitor the program.

As the Division of Ground Water Protection considers which quality approach is most effective in achieving its ground water protection objectives, it is important to note that the manufacturing industry trend for more than a decade places primary emphasis on a registered, independently monitored quality program rather than 100% product inspection. The ISO 9000 quality management and registration system was instituted in 1987 for general manufacturing. Subsequently, the QS 9000 variant was adapted for specific use in manufacture of automotive components. The precast concrete industry has adopted its own related manufacturer quality certification program through the National Precast Concrete Association (NPCA). NPCA registration demands that all of an organization's processes and elements that affect quality are identified, documented, and functioning effectively according to requirements determined by the organization and NPCA. It is a process of internal auditing, management review and the establishment of a quality system with defined procedures, work instructions and forms, all completely documented.

The precast product quality assured by NPCA registration of the manufacturer has led many state and federal organizations to require that all precast products must come from an NPCA certified plant. More than one-third of state departments of transportation, among the heaviest users of precast products, now require NPCA certification – this includes the Tennessee Department of Transportation. In addition, the U.S. Army Corps of Engineers now specifies that all precast concrete in drainage structures must come from NPCA certified plants.

The two approaches to ensuring septic tank quality and performance are contrasted in
Table 1. From this characterization, it is clear that implementation of a program requiring tanks to be manufactured under the auspices of an NPCA certified quality program is clearly superior and maximizes probability that the Division of Ground Water Protection will achieve its performance objectives.

Please call your local state representatives and senators and ask why the Tennessee Department of Ground Water Protection does not mandate NPCA plant certification to help ensure our ground waters are safe and usable. The Tennessee Department of Transportation already requires NPCA plant certification for all precast products delivered to a TDOT project.

Legislative contact information with contact phone numbers and emails

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