Passive French Drain



Major environmental concerns of the low-level radioactive waste management operations at Oak Ridge National Laboratory (ORNL) are that the groundwater in this location is near the soil surface and that there is a possibility of water infiltrating the disposal trenches at old solid waste storage areas (SWSA's). In the current SWSA (SWSA 6), a group of trenches (49-Trench area) collect and hold water with seasonal fluctuations ranging from 1 to 2 m. This seasonal wetting of the buried waste has resulted in the movement of 9OSr to a surface stream within the disposal area. To reduce infiltration and prevent waste leaching, the entire 0.44-ha 49-Trench area was sealed with a bentonite clay cover in October 1976. Subsequent monitoring indicated that the cover had not corrected the trench water problem, which suggested a faulty seal, an alternate recharge source, or both.