Anomalous, short‐term influx of water into seepage meters

Abstract

Laboratory and field tests revealed that there was an anomalous, short‐term influx of water into plastic bags after they were attached to seepage meters. Plastic bags (3.5‐liter capacity) were submerged in an 830‐liter tank of stagnant water; within 45 min, the volume of water in bags that initially were empty increased to 297 ml, bags prefilled with 1,000 and 2,000 ml of water increased by 160 ml, and bags prefilled with 3,000 ml decreased in volume. At Narrow Lake, Alberta, the anomalous, short‐term (30 min) influx of water averaged 237 ml to bags that were initially empty, but the anomaly was effectively eliminated when bags were prefilled with 1,000 ml of water before they were attached to seepage meters. The impact of the anomaly on calculated seepage rates was greatest when seepage rates were low, e.g. 0.3 ml m −2 min −1 . The anomaly may be due to mechanical properties of the bag, and it may be alleviated by partially filling bags before they are attached to seepage meters.