An environmental protection and detection system includes a vapor and gas impervious barrier extending beneath at least part of the area of an enclosure to prevent fluids leaked or spilled within the enclosure for flowing downwardly into the underlying soil and ground water and to prevent vapors and gases emanating from sources beneath the enclosure from percolating upwardly into the enclosure. Lengths of perforated pipe are positioned above the barrier and are connected to points outside the enclosure for use in detecting and removing contaminants leaked or spilled within the enclosure. Lengths of perforated pipe are positioned beneath the barrier and are vented to the atmosphere for preventing accumulations of fluids emanating from sources beneath the enclosure.