a gravel packed string for example borehole 12 could be lined with a conventional casing which is removed from the borehole as pipe string 10 is packed into it as shown in fig2 when it is desired to protect a large circular tank by means of the present system an array of multiple strings 10 may be placed under tank 14 to provide optimal coverage strings 10 may be placed in any one of several patterns including substantially parallel as shown or radiating from one or more circumferential points around the tank in any case the boreholes are preferably made sequentially so that a single drilling rig may be used to drill all of the desired boreholes with the rig being moved as necessary still referring to fig2 each string 10 forms an oblong zone of leak detecting effectiveness 18 indicated by dotted lines and a plurality of circular zones of cathodic effectiveness 19 indicated by dashed lines both zones 18 and 19 are influenced by soil composition moisture content porosity compaction conductivity and other variables hence the optimal number and arrangement of strings 10 may be determined based on the characteristics of the particular site and the size and shape of object 14 referring again to fig1 pipe string 10 comprises a length of tubing 20 one or more screens 30 one or more anode sections 40 and a terminal element 60 preferably tubing 20 extends from the well opening 13 at the ground surface to the zone that is desired to be protected in.