The farm on which Two Dam Sustainable is situated runs almost entirely on renewable energy and is 100% off-the-grid. We strive towards uncompromised sustainability in our day-to-day living and in all fields of our farming and operational practices.
The story of our conscious and committed approach begins in the kloof to the north-west where our drinking water supply originates from. Here a centrifugal filter was installed and a new pipeline laid for 1.2 kilometres to supply the farm downstream with its necessary water as well as assist in electricity generation. Unlike most water catchment collection points in the area, where almost every drop of water is extracted during dry spells, our filter, through its self-cleaning centrifugal action, releases approximately 10% of its water to continue downstream. This allows the indigenous riparian vegetation along the stream to remain intact, thereby controlling erosion of its banks and subsequent loss of valuable soil.
The Rainbow Trout RAS (Recirculating Aquaculture System) operates sustainably by being an energy efficient low head recirculating system which to our knowledge does not exist in commercial aquaculture in this form anywhere in Africa. This design requires comparatively low electricity as opposed to conventional high pressure RAS or high volume raceway cultures, which require and often pollute huge volumes of fresh water. Our system only requires as little as 5% of its total volume of fresh water per day and cleans, re-oxygenates and recirculates the remaining water continuously. The waste in the water is cleansed by two 10 000l bio-filters, each containing 4 cubic meters of bio media (extruded profile with a high surface area) which is oxygenated with blowers. This makes it possible for the growth of bacteria which then consumes suspended waste particles in the system, leaving cleansed water for the fish.
The farm makes use of a solar geyser for all hot water use. All lights on the farm are LED and energy efficient. We have installed remote sensor switches thereby reducing the need for copper cabling. All appliances were and are continuously quality-checked to be as highly energy efficient as possible.
A total of 31 kW photo voltaic panel arrays and accompanying 72 battery bank (168kWh capacity) with inverters and MPPT charge controllers, together with the turbine delivers the day to day electrical supply for the fish farm. For cloudy days the LP gas powered generator, which is more efficient and cleaner burning than conventional diesel generators, may briefly assist. The water pipeline allows for a pressure build-up of almost 7 bar, which in turn drives a micro hydro turbine. Thanks to this ‘high pressure, low water volume’ turbine we can generate up to 1 kilowatt of continuous electricity, which in turn assists our battery bank and takes over some of our electric load at night.
The farm is in a biological hotspot, as a combination of three vegetation types meet here, namely Fynbos, Renosterveld and Succulent Karoo. From the start we have initiated an Alien vegetation clearing programme where exotic invasive species, including sisal, black wattle, prickly pear, other exotic cacti species and large eucalyptus trees as well as saplings in the main stream have been systematically eliminated to encourage growth of indigenous flora and reduce water consumption.
The alien clearing project supplies the farm with sustainable building material and fire wood eliminating the need to look elsewhere for indigenous wood or importing wood altogether. To date our chicken coop, sheep kraal, shade net support structure of the fish farm, pig sty, goat pen, dry composting toilet enclosure and staircase railings have all been built with locally harvested eucalyptus poles.
We strive towards self-sustainability on the farm by keeping a few livestock and maintaining an ‘organic’ vegetable and fruit garden, thereby reducing our town trips/supply runs to once a week or less. All of the toiletries and cleaning products that we procure are Eco-friendly and/or biodegradable ensuring less impact on aquatic systems and its surrounding flora and fauna.
No pesticides or chemical fertilizers are used on the farm. Plants are enriched with animal manure and worm tea from our small worm farm and compost heap. All other compostables are used as pig feed for the farm’s resident pigs. Recyclables are separated, collected and brought to the Montagu waste and recycling facility. The fish farm also makes use of a dry composting toilet.
The Sustainable South African Seafood Initiative (SASSI) a division of the WWF lists South African farmed rainbow trout (Oncorhynchus mykiss) as a sustainable ‘green-listed’ species. Trout are the better alternative to some of the less sustainable fish, especially those fish stocks threatened by overexploitation in our oceans. To farm them locally in this unique and unconventional manner, with the lowest carbon footprint, truly makes them a highly sustainable and on top of that, delicious product.
Nutrient-rich water from the fish is collected in settlement dams and is used as fertilizer. This is applied to our newly established Pecan Nut plantation and the fruit trees around the farm, thereby eliminating the need for adding chemical fertilizers and reducing water consumption. The bi-products from fish-processing are used on the farm as feed for the farm's resident pigs. The majority of packaging is made from recycled plastic and is 100% recyclable. Research is being done into reducing our plastic footprint even further with alternative solutions.
Fingerling fish are procured as close to the farm as possible, with the majority of the fish coming from a hatchery in Keerom. The fish feed is procured from the nearest possible location whilst ensuring it is the best locally manufactured and specially formulated fish feed available.