The project was originally intended to demonstrate and update engineering guidance for the subsurface bioreactor technology, based on results from field-scale testing at the same site used for earlier column testing. The site was moved from the original location, however, and the engineering guidance has not yet been developed. Despite these logistical issues, the overall objective of testing the ability to enhance biogeochemical transformations at a field scale was still of interest, given the potential advantages of the technology. Although the demonstration was not successful, it is important to understand the reasons for these disappointing results if this technology is to be used with confidence in the future. This document has been prepared to summarize the findings and capture any lessons learned from this effort to demonstrate biogeochemical transformation at a field scale.