Procedure for the detection of soil contamination under a geomembrane

摘要

A method for determining the type, the extent and the location of a contamination which has arisen in the ground under a sealing membrane by means of a system comprising a perforated test tube arranged there, the open ends of which can be connected side by side to a quantity-limited air pump which can be closed by a valve, and a PID or FID measuring device with recording option and software for displaying tables and diagrams, consists of the following process steps: DOLLAR A a) Gaseous particles are sucked in via the test tube and measured and recorded in short steps with the PID or FID measuring device; DOLLAR A b) If excessive values are measured in step a), the test tube suction side is pressurized with blow-out air from the air pump and a measuring probe of the PID or FID measuring device is inserted into a tube area in front of the test tube suction opening; DOLLAR A c) the air pump is operated with an open suction valve without measurement for cleaning until the measured values are in a constant range; DOLLAR A d) the operation of the air pump is interrupted for a certain recovery period or rest period of 3 to 5 minutes; DOLLAR A e) Start of the measurement process with the valve initially closed and then carrying out a time-related measurement data acquisition and documentation for approximately the same duration as the suction measurement according to step a); and DOLLAR A f) Comparison of the measurement results according to step e) with those according to step a), a comparatively ...