Well Wishes. A Case on Septic Systems and Well Water Requiring In-Depth Analysis and Including Optional Laboratory Experiments

This paper describes the use of a case study to teach introductory chemistry students the chemical principles of solution concentration (especially ppm) and dilution, aqueous redox reactions, and stoichiometric conversions between different solution species. The case also provides an introduction to the carbon and nitrogen cycles as they pertain to wastewater. In the narrative, new homeowners in Vermont, worried about their septic system performance and the related issue of well water quality, have a series of phone conversations with their sympathetic Iowa relatives. Through instructor-facilitated, in-class discussion students then examine these issues, tracing the dilutions and chemical reactions that the household waste undergoes as it moves through the septic system and to the aquifer into which the well is tapped.

Supplemental materials available at JCE Online include the full text of the case with a supporting trade document about septic systems, optional quantitative laboratory experiments in which students measure nitrate and/or chloride levels in water samples, and a complete case teaching note. The case teaching note for instructors details case objectives, makes suggestions for adapting the case to various course formats, recommends questions for leading classroom discussion, outlines suggested student assignments, includes complete analysis of the data presented in the case, and provides background information on septic systems.