6 the Environments Associated with the Proposed Alternative Sites
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6 THE ENVIRONMENTS ASSOCIATED WITH THE PROPOSED ALTERNATIVE SITES The purpose of this section is to describe the environments associated with the proposed alternative sites. The information contained herein was extracted from the relevant specialist studies. Please refer to Section 3.5 for a list of all the relevant specialists and their fields of expertise and to Appendix E for the original specialist reports. 6.1 Brazil Site 6.1.1 Physical (a) Location The Brazil site is situated in the Kleinzee / Nolloth region of the Northern Cape, within the jurisdiction of the Nama-Khoi Municipality ( Figure 16). The site has the following co-ordinates: 29°48’51.40’’S and 17°4’42.21’’E. The Brazil site is situated approximately 500 km north of Cape Town and 100 km west-southwest of Springbok. Kleinzee is located 15 km north, Koiingnaas is 90 km south and Kamieskroon is located 90 km southeast of the Brazil site. Figure 16: Location of the proposed Brazil site in relation to the surrounding areas (Bulman, 2007) Nuclear 1 EIA: Final Scoping Report Eskom Holdings Limited 6-1 Issue 1.0 / July 2008 (b) Topography The topography in the Brazil region is largely flat, with only a gentle slope down to the coast. The coast is composed of both sandy and rocky shores. The topography is characterised by a small fore-dune complex immediately adjacent to the coast with the highest elevation of approximately nine mamsl. Further inland the general elevation depresses to about five mamsl in the middle of the study area and then gradually rises towards the east. There is a limited amount of undulation created by vegetated dunes. According to Low and Desmet (2007) dune patterns are quite evident at this site, with massive parabolic dune fields stretching south north for some distance along the coast. Most dunes appear to be undulating dunes with some gentle hummocking and are partially vegetated. In the south, parabolics are found nearer the coast. Further inland vegetated and semi-vegetated parabolics occur, but appear to be the remains of a much more extensive parabolic set, which is well-represented at Schulpfontein located approximately 30 km south of the Brazil site (Refer to Figure 17). Figure 17: Topographic location of the proposed Brazil and Schulpfontein sites in relation to the broader geographical area (Burger, 2007) (c) Climate The weather data for Brazil was acquired from the closest automatic weather station, which is located at Koiingnaas, approximately 47 km south of the Brazil site, as no site specific meteorological data was available. The climatic information was taken from Burger (2007). (i) Temperature The temperature measurements recorded at Koiingnaas in 2006 indicated a maximum of 40°C during November and a minimum of 4°C in June. The temperatures inland from the Brazil and Schulpfontein sites regularly reach an excess of 30°C. However, the cold ocean currents, with a mean annual temperature of 18°C, tend to reduce the inland temperatures. Temperature variations are induced by Berg wind conditions (off shore flow), whereby the temperature may exceed 35°C whilst the temperature can drop below 8°C during a temperature inversion. Nuclear 1 EIA: Final Scoping Report Eskom Holdings Limited 6-2 Issue 1.0 / July 2008 (ii) Rainfall The area is extremely dry and has a winter rainfall with a mean annual precipitation (MAP) of approximately 75 mm on the coastline increasing to 160 mm in the upper catchments. Rainfall measurements range between 63 and 166 mm with an average mean annual rainfall of 108 mm and a standard deviation of 19 mm. (iii) Wind At Brazil the surface winds are mostly southerly during summer, when vertical motion is suppressed by the south Atlantic high-pressure system. The area experiences a high frequency of strong winds (> 10 m/s) originating from the south and south-southeast. Strong winds occasionally occur from the west and west- northwest. Calm wind conditions occur for approximately seven percent of the time. The surface wind character is summarised in the wind roses below (Figure 18). Figure 18: Wind roses for the Koiingnaas monitoring station, used to infer weather data at the Brazil and Schulpfontein sites (Burger, 2007) Nuclear 1 EIA: Final Scoping Report Eskom Holdings Limited 6-3 Issue 1.0 / July 2008 (d) Geology and Seismology The geological and seismological information was taken from CGS (2007a). The geology of the 40 km wide coastal plain is dominated by Mesoproterozoic Namaqua-Natal Metamorphic province gneisses covered by Neogene to Quaternary marine and Aeolian deposits (Figure 19 and Figure 20). The basic crustal structure is dominated by northeast to north striking, variously dipping ductile foliations (showing plastic deformation) with intermittent sub vertical belts of ductile shear27 structures ductile shear belts produced under mid-crustal conditions some 1100 million years (Ma) ago. North-northeast striking tholeiitic dykes of the Gannakouriep Suite that became metamorphosed to sub vertical bands of amphibolites during the Pan African Orogeny that ended approximately 500 million years ago cut these structures. This dyke swarm is cut by north–striking brittle-ductile shear zones and quartz-veined faults formed during sinistral, transpressional shortening of the crust during the late Neoproterozoic. The latter shears are in turn cut by NNW to NW striking brittle Mesozoic faults formed during the opening of the South Atlantic Ocean and by a NE striking joint set related to oceanic transforms. All of these faults are orientated sub vertical. De Beer (2001) did not find any evidence of Cenozoic (65ma – present) faulting during approximately 10 years of field mapping in the area, but reported on evidence of listric faulting (spoon-shaped)found by the Atomic Energy Corporation (AEC) (currently NECSA) workers in that area. Figure 19: Geological structure, setting and seismicity for the Brazil and Schulpfontein sites (derived from a 1:1,000,000 digital database) (CGS, 2007a) 27 Shear describes a wide range of structures that develop in rocks as a result of tectonic stress. Nuclear 1 EIA: Final Scoping Report Eskom Holdings Limited 6-4 Issue 1.0 / July 2008 Figure 20: Simplified geology of the Brazil and Schulpfontein sites (SRK, 2007b) (i) Tectonics Aeolian sands, cover eighty percent of the land area, located within the 40 km radius of the site. Many faults may lie hidden beneath these sands. The largest faults encountered along the coast are two km south of the site, at Noopbaai and four km south of the Schulpfontein site. The faults are marked by breccias and quartz veins and strike approximately NNW-SSE, disappearing into the sea at both localities. None of these faults have displacements of possibly more than a few tens of metres. In the general vicinity of the Brazil site, faults are of a lesser nature (De Beer, 2001). Faults with probable displacements of the order of tens of metres, marked by sparse outcrops of white vein quartz, were mapped in the gneiss to the east of the Schulpfontein site. Nuclear 1 EIA: Final Scoping Report Eskom Holdings Limited 6-5 Issue 1.0 / July 2008 The offshore data shows that west dipping, coast parallel, normal faults occur at distances of 15 and 40 km offshore of the Schulpfontein site. Although no fault is shown to occur 15 km away from Brazil, marginal rift half-grabens28 are present and faults could well extend northwards (De Beer, 2006a). A fault 40 km away from the coastline is indicated to continue to the sea floor. However, the veneer of Quaternary sediments on the continental shelf is so thin that it is impossible to tell whether the faults indeed cut through the very youngest sediments. The faults penetrate the whole geological sequence that was affected by “gravity faults” (slumping) some 200 km offshore. Their relationship to the base of the Tertiary is indeterminable. There is currently no evidence that the Langklip fault created a surface rupture, which may have had more to do with the site conditions at the time of rupturing, and/or so called “fault die-out up” (Bonilla and Lienkaemper, 1991). The “dune lineament” at Hondeklip Bay may, however, represent a related fault that in fact ruptured through to the surface. (ii) Palaeo-seismicity Investigations in mining exposures along the Namaqualand coast revealed the presence of faulting and liquefaction in sediments that are less than five million years (Ma) old (De Beer, 2006a,b). Faults of similar strike, but unknown activity, in the Quaternary are present within seven kilometers of Brazil and Schulpfontein. The occurrence of an enigmatic “dune lineament” at Hondeklip Bay further compromises understanding of the age of Cenozoic faulting in this area and a substantial amount of work needs to be done to investigate these features before the risk to the Namaqualand sites can be defined more clearly. The absence of widespread secondary evidence implies that large earthquakes are comparatively rare. Not enough work has, however, been done to determine the recurrence interval of such events by palaeoseismological means. (iii) Seismic Hazard Preliminary investigations indicate that there is no fatal flaw with respect to seismic risk. This will be further substantiated during the detailed specialist investigation to be undertaken for the EIA phase. (e) Geohydrology The geohydrological information was taken from SRK (2007b). (i) Groundwater occurrence Two types of aquifer occur in the study area, namely intergranular (primary) aquifers in the unconsolidated sediments such as riverbeds or surficial deposits and fractured- rock (secondary) aquifers in the crystalline basement rocks. Two intergranular aquifers are of note, namely the Spektakel Aquifer and Schulpfontein-Noup Aquifer, which occur in the region (Refer to Figure 21 below). 28 Grabens, refers to a depressed block of land bordered by parallel faults.