once the act of parliament was obtained, edwards became the engineer for the project, and drew up the detailed plans, which grundy and smeaton checked and altered slightly, after which they had no further involvement with the scheme. construction was started in april 1763, and the drainage element of the project, which included the sluice, was finished in 1768, having cost £42,000. work on three locks and other work connected with navigation cost £6,000 and continued until 1771. the locks were located at stamp end, kirkstead and barlings. the grand sluice was a major construction which maintained the height of water above boston to near normal high tide level and had massive flood gates to cope with any tides above this. it was completed in 1766 and was effective in scouring the haven below it and increasing silting of the river above it.