What is the best method to measure and pay a contractor for a dredging project?
A contractor should always be paid on the actual “in-situ” amount of material dredged and not what is placed in the disposal area. In general, the contractor is given a set of cross sections showing water elevation and the sediment interface with the water and then told to dredge to that footprint. This is usually done on stations at 50 or 100 foot spacing. Immediately following dredging a given area, actual water depths are again taken and the difference at each station is the amount to be paid. This is usually done by computer programs using the average end area method to calculate yardage removed. In most cases an actual probing device is used and depth soundings are taken using sonar which gives fair results. On many projects the maximum dredge to elevations are given and the contractor is told not to over dredge. On some projects an over dredge depth is allowed, say up to 6″, and payment will be made to the contractor for the extra material. For contaminated sediment, dredging exa
