text: what is foundation of golf green? i want to know the layers of foundation golf green. the industry recognizes two two methods of green construction.    1.  usga step 1 - the subgrade the slope of the subgrade should conform to the general slope of the finished grade. the subgrade should be established approximately 16 inches (400 mm) below the proposed surface grade - 18 to 20 inches   step 2 - drainage step 3 - gravel and intermediate layers the entire subgrade then shall be covered with a layer of clean, washed, crushed stone or pea gravel  step 4. the root zone mixture the sand used in a usga root zone mix shall be selected so that the particle size distribution of the final root zone mixture  step 5. top mix covering, placement, smoothing, and firming step 6. seed bed preparation step 7. fertilization  2.  california there are some key differences between usga and california greens, and cost is just one. typically, usga greens cost $60,000 to $100,000 more than california greens on a 19-green renovation.  california greens also differ from usga greens because they consist of 12 inches of pure sand placed directly on the sub-base. in contrast, the usga method requires a 4-inch layer of gravel and, depending on material sizes, an intermediate layer of coarse sand to keep root-zone sand from filtering into the gravel. both methods call for a herringbone tile pattern to drain water from the green cavity.