Meet the Team – Nora Sadik and Natalie Lenz, Jacobs Water Engineers

Nora Sadik and Natalie Lenz, Jacobs Water Engineers

1) Pipe loop testing began last year and analyzes how different water (groundwater versus lake water) reacts with pipe materials. What are your roles in this project?

Nora – As a water engineer on this project, I had the privilege of having a particularly creative role in designing the pipe loop apparatus that would be able to provide good information on how the water switchover may impact Waukesha’s pipe materials. Together with the staff at the Waukesha Water Utility, we were able to develop a pipe loop apparatus that checked all the boxes. Practical expectations of excavating and preserving pipes from a community’s water distribution system were also considered. Following my role in the design of the apparatus, myself and Natalie Lenz, a water engineer at Jacobs, coordinated and executed the water sampling at the pipe loop apparatus which involved both onsite testing and a third-party laboratory. We focus on a range of water quality parameters including iron, pH, chlorine, and corrosion inhibiting chemicals to observe how the new water chemistry of Lake Michigan water interacts with pipes that have been exposed to groundwater for decades.

Natalie – My role on the project was to help with the experimental sampling design. My background in analytical chemistry was useful in determining the how, what, when, where, and why for sampling water chemistry parameters throughout the project. The pipe loop apparatus we designed allowed us to run multiple experiments, varying pipe material (cast iron and copper pipes), water chemistry of the incoming water, and the length of time water was held in the pipes before sampling. Due to our experience with chemistry lab work, we were able to save tens of thousands of dollars by performing some analytical sampling directly in the field at the pipe loop location, gathering real-time results and insights into the experimental data. Some samples were also sent to a third-party laboratory for more detailed analysis and quantification. We designed a database which used mobile data collection tools and automated QA analysis to facilitate with collecting, storing, and analyzing the thousands of data points collected during various experiments analyzed both in the field and at the third-party laboratory.

2) What are some interesting details about this pipe loop testing and how important is it to the overall switch to Lake Michigan water?

Nora – One of the most interesting aspects of the pipe loop testing has been the pipe scale testing, during which we analyzed the layers of scale accumulated on Waukesha pipes that have been exposed to groundwater for decades. Pipe scale formation is an important part of maintaining good water quality because it creates a protective barrier between the pipe and the water we drink. With the help of corrosion inhibiting chemicals, pipe scale formation can be enhanced while taking advantage of the water’s natural chemistry to form a stable and healthy scale layer. The pipe scale analysis and pipe loop test together gives us some insight into how the water chemistry of Lake Michigan will interact with Waukesha pipes, and what methods we can employ to maintain good water quality.

Natalie – An interesting aspect of the project was the physical change in water chemistry between the two water sources: Waukesha and Lake Michigan water. Waukesha’s current source of water is mostly from deep aquifer wells, meaning the water is hard due to high concentrations of calcium and magnesium. Lake Michigan surface water is softer, and therefore has a lesser potential to leave precipitate deposits and scale behind. Due to the chemical differences in both source waters, Waukesha ground water and Lake Michigan surface water also receive different water treatment processes. Waukesha water is disinfected using free chlorine, while Lake Michigan water uses the more stable disinfectant, chloramine. Sodium silicate is added to Waukesha ground water to prevent corrosion in the distribution system, while Lake Michigan water uses orthophosphate. The difference in water chemistry of the incoming water is central to the experimental design of the pipe loop testing, and will be informative when considering the resulting water quality before, during, and after the switchover.