Electrical liner integrity survey the earth below the geomembrane. The leak detection equipment features an ammeter in series with the applied potential circuit. The ammeter registers an increase in current in the presence of a leak, resulting in an audible tone and visual increase in the current level. The expected minimum sensitivity of the water-based bare geomembrane liner integrity methods is a one millimeter diameter circular leak. For the arc testing method, water is not required. A low voltage is introduced above the geomembrane and grounded to the conductive layer below it. In the presence of a hole, an electrical arc is formed along
Coal Measures Group the: In South Wales, the larger part of what had been the Upper Coal Measures now forms the Pennant Sandstone Formation in the overlying Warwickshire Group. The South Wales Coal Measures Group is preceded (underlain) by the Marros Group. Coal Measures Group The Coal Measures Group is a lithostratigraphical term coined to refer to the coal-bearing succession of rock strata which occur in the United Kingdom within the Westphalian Stage of the Carboniferous Period. Other than in Northern Ireland the term is now obsolete in formal use and is replaced by the Pennine Coal Measures Group, Scottish Coal Measures Group