Construction continued into January 1848, when it was discovered that the tailrace portion of the mill (the ditch that drained water away from the waterwheel) was too narrow and shallow for the volume of water needed to operate the saw. Marshall decided to use the natural force of the river to excavate and enlarge the tailrace. This could only be done at night, so as not to endanger the lives of the men working on the mill during the day. Every morning Marshall examined the results of the previous night's excavation.