Howard Hanson Dam Right Abutment Seepage: 2009 Interim Grout Curtain and Drainage Tunnel Improvements

摘要

Observations from the January 2009 flood indicated potential piping and internal erosion in the right abutment of Howard Hanson Dam. Due to the high impact to the infrastructure downstream, it was critical to enact interim measures to reduce to risk of flooding downstream before the next flood season in November. The grout curtain and drainage tunnel improvements were designed, contracted, and constructed in a period of 6 months. Preliminary data from the monitoring being performed during the 2010 conservation pool indicates that the interim measures are performing as designed and are reducing risk of flooding downstream. Although effective, these are interim measures, and studies are ongoing to evaluate the need for additional measures.