Colorado's Bench‐Scale Lead and Copper Corrosion Testing Protocol

Abstract

Key Takeaways The Colorado Department of Public Health and Environment developed a standardized protocol for corrosion testing procedures that is available as a resource for utilities. Immersion testing can be used to evaluate corrosion mechanisms, determine optimal corrosion control treatment, and examine the impacts of source water or treatment changes, while greatly reducing the cost and complexity compared with pipe loop testing. Exploring various resources, such as academic research, first‐hand utility experience, and water industry guidelines, can help a utility select the corrosion testing approach that best suits its needs and circumstances.

Comparison of coupon and pipe rack studies for selecting corrosion control treatment

“…A similar testing protocol has been used in other coupon studies (Bradley, 2018; Edwards & Triantafyllidou, 2007; Masters & Edwards, 2015; Nguyen et al, 2011; Tang et al, 2018). According to Arnold et al (2021), the extended stagnation periods used in this approach represent the long stagnation times that can occur in premise plumbing systems when a building is unoccupied. The authors also point out that weekly composite samples reduce the total number of metals samples that need to be processed.…”

“…Coupon studies use metal pieces of lead, copper, iron, or steel to compare CCTs that may reduce metals release (Arnold et al, 2021;Cornwell & Wagner, 2019;Kirmeyer et al, 1996;US EPA, 2016). These studies can normally be completed in a month to several months (Kirmeyer et al, 2004(Kirmeyer et al, , 1996.…”

“…Pipe loops are normally automated with timers to turn flow on and off to simulate periodic stagnation in residential systems (Kirmeyer et al, 1994). In closed‐loop systems, reservoirs of test waters are recirculated through pipe sections, oftentimes with pipes harvested from the distribution system (Arnold et al, 2021; Reiber et al, 1996). The test waters in the reservoirs are periodically replaced since the water quality can vary over time.…”

“…The test waters in the reservoirs are periodically replaced since the water quality can vary over time. This setup is used when test waters must be prepared in batches because a continuous supply of water is not available (Arnold et al, 2021). In flow through pipe loops, individual pipe sections are connected to a continuous supply of water and CCT alternatives are tested by using chemical feeds to augment in influent water to achieve the desired water quality (e.g., pH adjustment or corrosion inhibitor addition) (Kirmeyer et al, 1994; Reiber et al, 1996).…”

“…These studies can normally be completed in a month to several months (Kirmeyer et al, 2004, 1996). Coupon studies have been used to evaluate corrosion mechanisms, determine OCCT, and screen multiple CCT alternatives to be tested in pipe rigs (Arnold et al, 2021; Clark et al, 2015; Cornwell & Wagner, 2019; Edwards & Triantafyllidou, 2007; Kirmeyer et al, 2004; Korshin et al, 1999; Masters & Edwards, 2015; Pieper et al, 2016). These studies typically use new material coupons which lack the scales present in the distribution system needed to predict whether a change in CCT will disrupt existing complex scales formed over decades in distribution systems.…”