I am going to sod a 26,000 sq. ft. area with St. Augustine. Before I sod though, I will bring in enough topsoil to raise the grade about 4 inches in one rather large low spot that collects water after a rain. This water was keeping any grass from growing in that spot. O.K. The question: What do you guys think the best way is to: #1 till and remove the existing sod within the entire 26,000 sq ft area for sod prep? #2 spread about 40 yards of topsoil in this one low spot? The catch is that there is a very shallow sprinkler system installed already where I will be doing the install; 1 to 2 inches deep in many areas. Is there a method that any of you guys use to work over the tops of shallow poly pipe while not pulling any of it up or damaging sprinkler heads? All advice is really appreciated.