This paper shows a Lean Construction method being implemented with a bottom-up strategy, using spontaneous improvement as a tool for the implementation. To introduce the changes, all workers were trained on how to manage and identify the 8 types of waste, and presented to a simplified A3 thinking approach as a problem-solving technique. The implementation occurred on a large infrastructure project with a total extension of 83 km, using the construction of a water pipeline as an example, studying it for six months. To measure the results, the labor productivity rate and the average production-per-day rate were introduced as performance indicators, to analyse whether the implementation was successful or not. By the end of the study, it was possible to observe a correlation between the number of improvements made, the labor productivity rate, and the average production-per-day rate, which implied a successful implementation of the lean philosophy.