The readings of the water column with a probe in the piezometers are carried out weekly and enable us to determine the piezometric line. These readings showed a rather high piezometric level at the end of the summer of 2006 (around 3 to 5 metres deep at points where the height of the rubbish reaches 20 to 34 metres), which justifies the implantation of a new deeper network of drainage of percolates (approximately 7 m) at strategic points, accompanying the surface water network that exists there. At present readings show lower values for the peizometric line, which indicates that the drainage system is working well. Table 2 shows the values for May 209, a period in which the rain gauge installed in the gatehouse of the landfill showed an accumulated rainfall of 7.10 mm, which is characteristic of the end of the rainy period.