The purpose of this test is to find out the type of soil at the bottom the pond, and thus, to determine the amount of sodium bentonite needed to seal the pond. Perforate the bottom of a can, a pail, or a drum and put two inches of gravel in the bottom. Take a sample of soil from the area to be treated. Be sure that the sample used is representative of the entire pond bottom. Cover the gravel with 6" of the sampled soil. Tamp the soil, then elevate the container so that the bottom is open to drain, then fill the container with water. Once the container is filled with water, observe the results.
Based on the result, repeat the procedure using the chosen application method and the recommended bentonite dosage to seal the pond. If the test doesn't seal off the leak as desired, repeat the procedure with a slight increase of bentonite dosage on each test until the leak stops. Keep in mind that an additional 25% to 50% more bentonite could be needed on large scale projects to allow for greater water depths (water pressure) in the pond.
If you plan to use the BLANKET METHOD, apply a blanket of bentonite over the soil sample in the can. Cover with 3 to 4 inches of soil and fill the can with water. If the SPRINKLE METHOD will be used, apply the bentonite by sprinkling it on the water surface after you have filled the can with water. Repeat the procedure until you find the minimum amount of bentonite required to prevent or reduce water seepage to an acceptable rate.