3. Intangible Assets a. Depletion Baker purchased a gravel field for $500,000. It should produce gravel for 8 years and then have a salvage value of $50,000. The DNR requires that the land be restored so that it can be used as a park. The anticipated restoration cost is $75,000. Money would be set aside for this purpose and would earn a 4% annual return. Calculate the depletion base At the end of the first year, 50,000 tons of gravel are removed and it is estimated that 450,000 tons remain at year-end Calculate the cost per ton of gravel for the first year