Marais Dam Traditional Cache
Wiele: Cache has disappeared - possibly due to cleaning in the area. Will not be replaced in near future.
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Difficulty:
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Terrain:
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Size: 
(small)
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About the cache:
The cache is located in an area suitable for visitors to get out of their vehicles, and have a braai or picnic.
Rietvlei Nature Reserve
The Rietvlei Nature Reserve is one of the largest, if not the largest, nature reservation in an urban suburban area in the world.
The Rietvlei Nature Reserve was originally created in order to protect the catchment area or the Rietvlei dam against pollution and unwanted habitation.
An entrance fee of approx. R40 per adult is payable upon entrance to the park.
History of Rietvlei Dam
1930: The construction of the Rietvlei dam wall and the supporting infrastructure started in 1930. Due to the fact that very few earth moving machines were available at the time, manual labour was used for the construction of the earth and stone dam wall. Mules and horses were used to pull the carts and sleds which was used to transport the building material to the dam.
The dam wall is an earth and stone structure, with a waterproof core and a concrete spillway on the one side. Water is fed through an inlet and flows through a pipe that passes through a concrete tunnel to the water purification plant.
1977: By 1977 the Rietvlei Water Scheme was providing 34 mil litlres of water per day to the City Council of Pretoria.
1983: By 1983 the Rietvlei Water Scheme was supplying approximately 30% of Pretoria’s fresh water needs.
1986: In 1986 the Rietvlei dam wall and the water purification plant were upgraded in order to ensure its integrity during a one in one hundred year flood. This work was awarded with an engineering award for excellence.
1986: Due to an decrease in the quality of the dam water in 1986, it was decided to appoint a group of consulting engineers, to investigate the cause of the decreasing quality in dam water. This was done with the assistance of the National Institute for Water Research at the CSIR.
1986: In 1986, water from the Dolomite areas was extracted by means of boreholes. A reservoir tank and pipe system were constructed for this purpose.
In the same year some of the overhead power lines were laid underground.
1988: In 1988 the Rietvlei dam wall was raised to its present height.
1989: In 1989 the rehabilitation of the marsh area started in order to allow it to function as a biological filter of the water entering the dam.
2008: By 2008 the Pretoria water consumption had increased to 850 mil liters per day of which Rietvlei WS was supplying 41 mil liters per day.
History of the Marais dam on RNR:
1875 – 1934: A dam existed at the site of the Marais dam that was most probably built by one of the early owners of that part of the Rietvallei farm.
1934 – 1989: This dam was strengthened during the construction of the Rietvlei dam in order to reduce the build-up of silt in the main dam.
A weir was later built downstream of the dam for the same purpose.
A number of irrigation canals were built from the dam to the areas used for agricultural production to the north east of the dam.
1934: The water supply from the dam by means of these canals was controlled by a syndicate led by a person by the name of Marais. He dam has therefor been referred to as the Marais dam ever since.
1989: In 1989 the Marais dam was cleaned of silt and the dam wall repaired. The canals have however fallen into disrepair and are not is use anymore.
Additional Hints
(Decrypt)
Orybj gur ybyyvcbc
Treasures
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