Gardeners, farmers, botanists, horticulturists, etc. will wax poetically about the many virtues of top soil, and we can agree with most of them. Unfortunately, top soil exists at the opposite end of the value chain in construction, and we seem to have more than our fair share of beautiful, rich, top soil. All of which must be removed and replaced with something even more exotic: Engineered Fill. So, our “Big Dig” has been expanded.