A common feature of civil engineering design is the ""french drain"", a trench intended to intercept and collect groundwater and transfer it laterally to a sump. The environmental marketplace ahs created a larger demand for these drains for the purpose of the collection of contaminated groudwater. This paper reviews the current practice as illustrated by case studies. A collection trench for oil, another for a chemical containment and a drain constructed inside a slurry wall at a landfill site.