Industrial Potable Water Treatment
Corrosion Control Treatment Evaluations to Meet EPA Lead and Copper Rule Compliance
While the U.S. Environmental Protection Agency’s current Lead and Copper Rule has dramatically decreased drinking water lead exposure, too many people are still being affected by this contaminant. Hence, the EPA is about to finalize revisions that further reduce potential lead consumption. The revised rule could require water purveyors of all sizes to conduct additional evaluations to identify the sources of lead, remove them as quickly as possible and reduce the corrosion of the lead sources until they are removed.
One key potential revision introduces new trigger levels. Proactive corrosion control treatment evaluations, public outreach and lead service line replacement plans would be required if the new trigger level of 10 ppb is exceeded. When the action level at 15 ppb is exceeded, additional requirements would be applied for public education, lead service line replacement, water quality monitoring, and corrosion control treatment and source water treatment. System-specific requirements would depend on how the primacy agency implements the federal rule.
Many water purveyors — especially those that are not municipal agencies — are not familiar with the expected revisions or the process to meet compliance. Complying with these changes may be challenging for those with limited resources. Assembling an experienced team will be crucial to developing a strategy to return to compliance in a timely manner and protect community health. We have provided guidance to a variety of clients with these same challenges.
Recently, I had the pleasure of assisting an industrial client who owns and operates a large Midwest industrial facility and is also the drinking water purveyor to the site’s 800 employees. The company received a lead action level exceedance and needed guidance to meet compliance. Their historical approach to managing corrosion was performed reactively to water quality measurements but is no longer allowed by the state. We were hired to determine if treatment was required and, if so, what type of treatment would be most effective for their specific needs.
To gain an understanding of their unique system, I visited the site to explore their facilities with staff. I learned about the multiple on-site wells that supply the potable water system, viewed the variety of distribution and plumbing materials used and identified which taps were frequently used for consumption. I also listened to what preferences or limitations the client had for the installation of a new treatment system. The multiple on-site wells, unique distribution network and varying consumption patterns required close collaboration to develop a strategic approach for the corrosion control evaluation and treatment system needs.
Creating a water quality sampling plan to benchmark existing conditions was the next step, as it provided key information for future corrosion control optimization. Developing this plan was challenging because water usage patterns for industrial facilities differ considerably from municipal water agencies, and especially for this site which has a larger service population than those of many municipal water agencies. In multiple parts of their system, the water remains stagnant over the weekend or at building taps that are only used occasionally.
I worked with company staff to conduct monthly water quality monitoring over a six-month period. This data was used to understand the building plumbing conditions that impact the release of metals in order to make effective treatment decisions. The results of these evaluations indicated that copper corrosion was occurring simultaneously with lead corrosion and needed to be considered in the treatment evaluation. In addition, elevated manganese concentrations were observed in each of the well water sources. This constituent can be sequestered with adequate chemistry or removed from the source water via several treatment options.
Following the water quality evaluations, chemical treatment strategies such as phosphate-based inhibitors, pH/alkalinity/dissolved inorganic carbon adjustment and silicate inhibitors were evaluated. A phosphate-based inhibitor was identified as the most appropriate corrosion control treatment method based on a variety of water quality parameters. I reached out to vendors to see what corrosion inhibitor options were available and received recommended dosages and chemical costs. Bench scale testing was then conducted to screen corrosion inhibitors, evaluate the effectiveness of corrosion control treatment and optimize dosages. I developed a testing procedure for the client that considered a variety of raw water sources, metal coupons, chemicals and dosages. The following outlines the sample combinations for testing:
- 3 well water sources – Well A, B and C
- 3 metal coupons – copper, lead, and leaded brass
- 2 orthophosphate/polyphosphate chemical blends
- 3 dosages per chemical
More than 60 unique jar combinations were evaluated, and the testing was conducted in parallel with the design and installation of the treatment system. During the testing, I provided guidance and reviewed water quality results as we received them. Pipe loops could not be constructed for their system due to the variety of parameters tested and the aggressive schedule to meet compliance. The rates of corrosion were determined based on changes in water quality over time and were used to assess the effectiveness of the phosphate-based treatment chemicals. The coupon testing was completed to increase confidence in the selected chemical treatment option and identify an initial dosage for the treatment system.
During the corrosion control treatment evaluation, I developed the design basis for the treatment system that ensured it would be suitable regardless of which well water was supplied. This document includes details about the corrosion inhibitor injection locations, treatment system layout and space requirements, and equipment such as metering pumps, chemical storage, instrumentation/controls. An enclosure with heat and safety features is also included.
For their unique distribution system, the treatment system was located at one of their wells with two injection locations to ensure that the inhibitor reached the entire distribution network. In addition to the design basis, I also provided guidance with cost estimates (capital, operations and maintenance), the project implementation schedule, permitting support on state operation certification requirements, and health and safety issues and mitigation. The design basis was approved by the state and county.
This facility’s path forward to meet compliance consisted of working closely with us to address the county and state’s concerns. While the final version of the LCR revisions has yet to be released, we know the scope will be extensive and complex. It will be essential to have a sound response plan that identifies uncertainties and lays out a thoughtful approach to each of the rule’s major elements. I would be happy to learn more about your facility and help you achieve LCR compliance. I can provide support with water sampling plans, corrosion monitoring, condition assessments, decision economics, optimizing corrosion control treatment and treatment system design. Optimizing corrosion control treatment is important to me to ensure that public health is protected for all communities.