High-speed ditchers

Abstract

By the year 2000, over 120 000 ha in Florida will have been surface-mined for phosphates. Nearly 60% of the mined land consists of clay settling ponds. This clay is a very fertile soil but with low load-bearing strength and with extreme drainage problems. In order rapidly to restore these mined lands to agricultural production, surface ditches are needed to drain ponded water. The construction of these surface ditches with conventional earthmoving equipment is impossible because the clay is still fluid to a depth of several metres. A proposal was made to pull a ditching plough across ponds with a cable and double winch apparatus. An economical pair of winches were assembled by modifying farm tractors to spool the cable. A boat-shaped, drainage plough designed for this system was fabricated and made water-tight so that it would float. A double mouldboard plough bottom was attached with a hinged mount to one end, allowing the depth of cut to be adjusted. Ditch excavating was only attempted while the plough was being pulled outward from the drainage outlet and the 1·2m wide channel was swept clean when it was rapidly returned. This mode of operation was followed to avoid the possibility of the plough becoming stuck in the channel. Under typical operating conditions, the system has been able to excavate at a rate of nearly 2·0 m3/min and form ditches up to 600 m in length.