Monty Python fans will know the story of the man who gets up every morning and cleans the lake but that is exactly what Howard and Ann Emeny do. Howard and Ann own Lakeweed Harvesters and Contractors and clear weed from the lakes of central Bay of Plenty region.
Introduced aquatic weed clogs many of New Zealand’s waterways. It affects aquatic life and prohibits access and use for recreational users. Lakeweed Harvesters remove the weed mechanically, using a harvester mounted on a three metre by seven metre pontoon vessel. The different components of the harvester are all hydraulically operated with the pump being driven by a 3 litre diesel engine.
The vessel is propelled by paddle wheels on either side of the pontoon and is steered in a similar fashion to a bulldozer. The front scoop has two horizontal and one vertical cutter bars lined with a sical blade cutting system. A conveyor is lowered to collect the weed, where it travels up onto a second conveyor before it is dumped into a twelve cubic meter travel cage. After transporting to the shoreline, the travel cage is emptied and the weed is transported to a designated dump site before it is taken to a worm farm and turned into fertiliser.
The operation works under strict standard operating procedures to ensure maximum weed is harvested and because it works over water stringent safety, health and environmental protocols are followed. Lakeweed Harvesters do not use chemicals and where necessary use biodegradable products. In the harvester’s hydraulic system, Howard and Ann use eni Arnica S 46, supplied by TransDiesel. This product has a high viscosity index and so gives outstanding performance across a wide temperature range but in the event of a spill to water, Arnica S 46 will degrade in a short period of time without harmful effects to the environment.
Lakeweed Harvesters and Contractors have many references on their website, but one in particular highlights the effectiveness of their operation. Richard Mallinson of the Bay of Plenty Regional Council says that between 3.2 to 4.3 tonne of weed has been removed annually from Lake Rotoehu since 2008 resulting in a dramatic improvement in water quality.