ABSTRACT
Steadily increasing foundation seepage recorded upon filling of the recently completed Lavumisa Balancing Dam was cause for some concern. Attempts to reduce seepage by means of a partial clay blanket did not have the desired effect. Rather than grouting of the entire centre-line, a contact zone between the founding lava and intrusive dolerite was identified as a possible seepage path and grouted. In spite of extending the grout curtain, continued monitoring of the seepage revealed little overall reduction in seepage flow rates. These foundation grouting results are discussed in the light of this apparent failure in achieving a sealing of the foundation. The predominantly fine fractures are evidently not groutable. In such cases a clay blanket is a better option, provided specific design criteria are adhered to.
