Abstract:Environmental supervision is an important auxiliary means for "three simultaneities" acceptance administration of construction projects, and also is an inherent requirement for construction units to rely on third parties to strengthen environmental protection supervision throughout the entire process. Taking anti-seepage treatment of acid water reservoir as an example, it has taken measures to resolve the issue of acidic water leakage at dam heel such as anti-seepage for the dam body and foundation, anti-seepage of drainage tunnels, and improvement of downstream seepage recovery system. These measures involve concealed works such as cement grouting, chemical grouting, and HDPE geomembrane anti-seepage. Based on the characteristics of the project and combined with environmental impact assessment document, design document, etc, key points of environmental supervision for concealed projects construction, implementation of pollution prevention measures, and compliance with environmental protection behaviors are comprehensively analyzed, and some suggestions are proposed. The research results can serve as effective internal environmental administration guidance for construction units, and also can provide reference for environmental management of similar projects.