Contents preface (VII) introduction 1—37

Partially Penetrating Toe Drains: If undesirable foundation seepage conditions are likely to develop during the operation of a dam, a partially penetrating toe drain (Fig. 15.20) should be constructed so as to improve the seepage conditions. The perforated pipes are connected to gravity outlets. These drains will not be effective when the foundation is such that the drains

512 IRRIGATION AND WATER RESOURCES ENGINEERING
are separated from underlying pervious strata by impervious layers. In such cases, relief wells are more suitable.