Used to backfill or seal soil in installation of Soil Water Samplers. 

BENTONITE SEAL is extremely important in "sealing" the
sampler into the installation hole and preventing back flow down the
drill hole. If your expecting to get realistic samples of soil pore water
then it's paramount to prevent bias from rain water, irrigations etc. from
preferentially travel down the installation drill hole. This NSF approved,
30-50 Mesh, high density (65lbs /cu ft.- 29.45 Kg /.028 cu m), granular
bentonite is the prefect expanding clay sealant used above the silica fill
near the drill hole bottom and as a top seal near the surface.

Available in 5lb, 10lb, and 50lb bags.