Thursday, July 19, 2012
The first setup that we tested was the one with a layer of 100 marbles about 3 inches above the bottom of the outer column with about 6 additional inches of sand on top of the marbles. When testing with the falling head test, the column was always above the level of the marbles. We have previously done this test with the f65 sand and today we were testing the lake superior sand. After finding one of our columns broken yesterday, Susa went out and bought 2 new columns. One is the same as the the columns that we have had before the other was a bit taller and thinner than the columns that we have been using. The two new columns were set up yesterday afternoon, so that would be allowed to settle overnight like we have been doing. The big column was prepared with lake superior sand and only 7 marbles placed inside the column. There was not a huge change in the k values when only 7 marbles were placed in the column and no marbles were outside. The smaller tube was filled with some f50 sand for further testing since we have not used that sand since we changed our method. Since this column is much thinner we think that there might be some edge effects from the two columns used in the set up of the falling head test being so close together. To solve this problem we placed some superior sand in the thinner column and will test it tomorrow. We chose superior sand since we feel that we have some really good data on this sand to compare to the k values that we will get tomorrow to see if the thinner column effects the k values. Tomorrow we also plan on lodging some more extensive testing of the superior and f65 sands in terms of distance from the absolute bottom of the column and the k value trends.