Seepage Monitoring of an Embankment Dam Using Resistivity Method: A Case Study of LUSI Mud Volcano P.79

Seepage Monitoring of an Embankment Dam Using Resistivity Method: A Case Study of LUSI Mud Volcano P.79 - P.82 Embankment

Husein, Alwi / Santosa, Bagus Jaya / Bahri, Ayi Syaeful

Abstract

Since the Lusi Mud volcano erupts in Sidoarjo, East Java, on May 2006, soil embankments have been built to keep hot mud within the ponds. Unfortunately, since the embankments were sitting on a poorly weak ground, land subsidence intensively occurred around the embankments. These subsidences are mainly caused by water seepage penetrating the embankment. To observe the part of the embankment that is vulnerable to water seepage, DC Resistivity method, being a non-destructive and versatile method, is used to monitor the subsurface condition of the embankment. P.79 - P.82 embankment, which has collapsed on December 2010 is highlighted in this study because it has the lowest height of all part the embankment, directly adjacent with water from the mud volcano in the inside and field crop on the outside. The research will show the fluctuating results of the water seepage in the embankment during the timeline of February 2012 - October 2013 which, unlike the result of another area, is highly affected by the water level at each measurement. The embankment height during each DC Resistivity measurement is also measured to compare the subsurface result with the condition on the surface. The resistivity subsurface cross section shows increasing water seepage in each measurement (February 2012, July 2012 and October 2013). Alarming seepage level displayed in December 2012 which is presumably triggered by the increase of water level during rainy season is also followed by cracks occurred in the surface.