In a homogeneous clay dam, where should a geofabric be placed to prevent clogging of a vertical chimney drain?

Placing a geofabric on the upstream face of the chimney drain is essential for maintaining adequate drainage in a homogeneous clay dam. The primary function of the geofabric is to act as a separator between the fine-grained clay and the drainage material in the chimney drain. This placement helps to prevent the clay particles from washing into the drain and clogging it.

By positioning the geofabric at the upstream face, it allows water to flow through the geofabric while providing a barrier that retains the clay particles, thus ensuring the effective function of the chimney drain. This strategy is vital to maintaining the stability of the dam structure and preventing potential failure due to water buildup or excessive pore pressure that could lead to seepage issues.