Tower location shifted SW, and grouting done under foundations. Some repeat readings showed that most grouting migrated NE, and eastern anomaly was eliminated. Drilling helps identify this effect. Excess mass may estimate grouting required, as well as verify results. Necessary precision is easier to attain on a construction site than elsewhere, with little extra cost.
More sites is more cost effective than more readings at each site.
Each reading is of importance, and the usual spatial aliasing rules etc are less significant than getting anomalies to drill. When a method is applied close to its resolution limits, there is less room for problems and errors. End of case history summary. Last updated March, 1999.