Kerriefontein and Darling Wind Farm, Western Cape

2010 - 2011

Role: Project Coordinator at the Environmental Evaluation Unit (EEU), University of Cape Town.



Botanical – Nick Helme (Nick Helme Botanical Surveys)

Avifaunal – Chris van Rooyen (Chris van Rooyen Consulting)

Visual – Bernard Oberholzer (independent landscape consultant) and Quinton Lawson (MLB Architects)

Heritage – Jayson Orton (UCT Archaeology Contracts Office)

Noise – Brett Williams (Safetech)

Social – Kirsten Scott (EEU, UCT)


An Environmental Impact Assessment (EIA) for an extension of the existing Darling Wind Farm (est. 2008), adding 14 or 16 new wind turbines to produce around 20MW of renewable energy into the national grid.


This EIA was conducted for a project to develop the ‘Kerriefontein and Darling Wind Farm’ on a site located along a regional transport corridor between Yzerfontein and Darling, 85km north of Cape Town. The proposed wind farm has a capacity of 20-21 MW for national distribution.

The original proposal for the existing Darling Wind Farm was for 10 turbines of 1.3MW output; however only a first phase of 4 turbines was approved and became known as the Darling National Demonstration Wind Farm. In 2006, Darling Wind Power entered into a Power Purchase Agreement with the City of Cape Town for a term of 20 years – the first of its kind in South Africa.

The EIA commenced in March 2010, conducting a Scoping and EIA process involving botanical, avifaunal, visual, heritage, noise and social specialist studies and a Public Participation Process.

The process was conducted in terms of the ‘Gold Standard’ certification, an independently audited methodology for project development, which delivers carbon credits through a framework more rigorous than the Kyoto Protocol CDM project requirements. Achieving CDM approval and the Gold Standard would allow the Project to qualify for funding.

The EIA process aimed to ensure the net benefits from harvesting renewable energy outweigh the site specific impacts, in order to render this development desirable.

An Environmental Authorisation was received from the national Department of Environmental Affairs in November 2011.


The predominant land use on the site is agriculture. Vegetation is mostly disturbed and partly rehabilitated, but also includes pristine areas, as well as fallow agricultural land of low value.


Geissorhiza radians (kelkiewyn) is a spectacular spring bulb from seasonally wet clay and loamy flats in the Darling and Swartland area, Red Listed as Endangered, and is known to occur in the study area. (Left)


There were originally two vegetation types in the study area; about 40% of the study area supported Swartland Granite Renosterveld, with the sandy western parts supporting Hopefield Sand Fynbos, both recognised as threatened. Thus all remaining natural vegetation in the study area is of high sensitivity and conservation value. About 16% of the study area is fallow agricultural land with very little natural vegetation, and this is the low sensitivity portion of the proposed site.   Natural vegetation in moderate or good condition covers ~84% of the area. Most of the vegetation in good condition is either on previously uncultivated small, rocky outcrops, in drainage lines (wetlands), or in the western parts, dominated by infertile sandy soils, which are not suitable for cultivation.


Despite having a high diversity of plant species, fynbos and Renosterveld has a relatively low diversity of bird species. Records indicate that 13 prioroty bird species occur within the site or on adjacent areas of habitat.


Impacts on bats were not identified as a significant issue during Scoping, until Cape Nature submitted a comment on the bat issue in response to the Scoping Report. A the time there was an ongoing debate amongst the scientific community around the issue of impact on the birds and bats from wind energy facilities. Draft best practice guidelines for avian monitoring at wind facilities were produced by the Endangered Wildlife Trust and Birdlife SA and at the time of the EIA. However, a set of guidelines for bats was not yet published. The decision was therefore taken not to persue a bat study.


The rolling hills constitute a scenic rural landscape in an area famed for its spring wild flowers. This aspect, together with the recreation activities of the nearby West Coast, means that the area is an important visitor and tourist destination. Scenic routes (R27 and R315) and protected areas tend to increase landscape value in visual terms of the site environs, and therefore the visual sensitivity.



The area has a history of agriculture and ploughing that has transformed much of the natural landscape. The archaeology of the area is not well known. The Darling Hills would undoubtedly have been used extensively by the Khoekhoen people for grazing their stock and their settlements would likely have dotted the open landscape. The local geology is not conducive to the formation of rock shelters and none are known. Stone artefacts are routinely found of various ages in the wheat lands of the Cape and such finds would be expected. The presence of Stone Age people in the general area is well documented by the excavations at Yzerfontein 9 km to the south-west. Two other surveys in the vicinity of the study area found no heritage resources (Halkett, 2001; Hart, 2008).



The site is situated in a rural farming community. Several homesteads are located on the property where the turbines would be erected, as well as on neighbouring farms. The general ambient noise at each location varies substantially as the ambient sound is influenced by human activities, as well as vehicles and animal sounds.



Evidence shows that there is already a growing tourism industry in the area, which has considerable social, cultural and environmental assets, and the potential to develop this further. 


The local population is characterised by low levels of education and skills and low incomes; however unemployment levels are moderate in comparison to national levels. There is an increasing trend of out-migration of white youth for employment elsewhere and in-migration of white mature age groups for retirement or commuting lifestyle.



 During construction, there will be a loss of natural vegetation. About half will be permanent, and the other half temporary. Some of the primary direct impact is loss of portions of the the local populations of some of the plant "Species of Conservation Concern". Reduction in already small population numbers below a certain threshold is known to have negative consequences for that population, and may lead to local extinction. Option 1 would require the loss of 3 ha and this is assessed as a low-medium negative impact. Option 2 would require the loss of 4 ha and this is assessed as a medium-high negative impact. Option 1 is the preferred development option, and may have a low positive overall botanical impact if all mitigation proposed is enforced.

During operation, indirect negative impacts such as habitat fragmentation; disruption of the natural fire regime; and possible introduction and spread of alien invasive plants and insects, are likely to occur, but will probably be relatively insignificant, especially in the context of the ongoing farming operations in the area.

For Option 1 this negative impact is assessed as low-medium without mitigation, for Option 2 this is assessed as medium-high without mitigation. Fortunately these impacts are relatively easily managed.

Potentially positive ecological impacts have been indentified, namely the opportunity to formally conserve significant priority areas of natural habitat by registering the medium and high sensitivity portions of the property with Cape Nature's Stewardship Programme for private landowners. Most of the natural vegetation in the study area is not currently being adequately or optimally managed.

Another positive impact could arise through the opportunity to fund and implement an Operational Environmental Management Plan throughout the  site, focussing on the  most important issues, which are alien vegetation control, fire management, rehabilitation of ecological corridors, and grazing impacts.

 Figure 1: Oblique aerial image showing existing 4 turbines and schematic botanical sensitivity map. Red area is of high sensitivity; yellow medium; other  areas within study area are of low sensitivity.


fire Up until November 2010, the 86 hours of observations conducted by Jenkins in 2002 - 2003 constituted the only pre-construction avifaunal data ever recorded in South Africa at a proposed wind farm site. In total 116 hours of monitoring at the site was completed between January 2002 and February 2011.

Counts of priority bird species and all raptor species commuting over the site were conducted from the crest of Moedmaag Hill, facing west along the proposed turbine line. Details of the mode of flight (flapping, gliding, soaring), direction of travel, and approximate bird flight paths was also recorded.

Impacts on avifauna could result from collisions with turbines; displacement of priority species; or habitat loss, which may also result in displacement of priority species due to the footprint of the Project.

Estimated collision rates have been calculated based on monitoring of priority bird species and all raptor species commuting over the site. It would seem from analysing the data that the Project will not pose a significant collision mortality risk to priority species, with Jackal Buzzards emerging as the highest potential risk.

With Jackal Buzzards specifically, the estimated avoidance rate may be more than 98%, as the birds observed on site are most likely a resident pair. They have clearly become used to the four existing turbines. Whether this would also be the case with inexperienced, juvenile birds remains to be seen.
Fortunately, the phenomenon of mass migrations involving thousands of birds is not a feature of the project site; however migratory raptors, i.e. Steppe Buzzard Buteo vulpinus and Yellow-billed Kite Milvus aegyptius were recorded during the summer and autumn monitoring period.  If the Project causes high numbers of casualties of these migrant raptors, this would constitute a significant negative impact of the facility.


Bird mortality due to collisions with the turbine blades is assessed as a negative impact of low significance to decision-making, without mitigation. Given the potential inaccuracy of the predicted collision rates as a rough indicator of risk, the only way to verify this would be to conduct carcass searches during the period when the above birds are present.


assessed Figure 2: Priority species recorded at the site during 116 hours of monitoring

International studies have been employed to establish the likelihood of displacement of birds due to the presence of a wind facility. Although more displacement of birds due to the presence of a wind facility. Although more studies are needed, research indicates that with few exceptions, the displacement effect of wind developments on raptors is low to neglible (Madders and Whitfield, 2008). This seems to be supported by the results of the limited post-construction monitoring conducted at the existing four turbines.

At the project site, direct habitat loss is not regarded as a major impact on avifauna, relative to other potential impacts such as disturbance or collisions.


The visual impact assessment focussed on a number of criteria to assess the turbine configurations for Option 1 and 2; the substation; and the internal access roads.

Visibility of facilities: Views from the R27 and R315 roads adjacent to the site are the most significant and could affect the most receptors including tourists.

The visibility of the wind turbines is limited from some viewpoints because of being screened by Moedmaag Hill and view shadows created by the hilly topography.

The wind facility will be visible for up to about a 10km radius. The visibility is determined by ridgelines. Wind turbines are tall but slender. The view catchment area would only be marginally increased by the addition of 14 to 16 wind turbines over the original four turbines.

Landscape integrity (effect on character of the area): The Project contrasts with the rural landscape. The existing four turbines and power lines are considered as existing disturbance and reduce the visual significance of the proposed facility.

Cumulative visual impact: The Project would add to the four existing turbines, but remains a fairly small facility. An additional facility is proposed nearby Rheboksfontein.

Overall this results in a visual impact rating of medium-high for both Option 1 and 2 turbines; a medium rating for the internal access roads.

The difference between the Option 1 and Option 2 layouts are assessed as marginal in terms of visual impact, the viewsheds and visibility as shown in photomonrages.

Figure 3: Visual Impact Assessment



No significant issues aside from those related to the visual impacts were noted during the scoping assessment and thus an EIA phase assessment was scoped out of the process.


During operation, the effects of low frequency low frequency (sleep disturbance, nausea, and vertigo) are unlikely to impact upon residents due to the distance between the plant and the nearest communities. Sources of low frequency noise also include wind, train movements and vehicular traffic, which are all closer to the residential areas.

Ten noise sensitive receptors were indentified around the site. For Option 1 and 2, it was calculated that the noise produced by the wind turbines will exceed the 45dB(A) day/night limit only at the Windhoek Farm Workers homes at the 12m/s wind speed which was the maximum speed used.  As the wind speed increases, the ambient noise also increases and masks the wind turbine noise. The critical wind speeds are thus between 4-6 m/s when there is a possibility of little masking. The location of the Option 1 and 2 wind turbines all met the recommended 500m setback distance from the existing noise sensitive receptors.

The impact of the operational noise on the surrounding environment is assessed as having a medium negative significance to decision-making without mitigation.



The main benefits during all phases of the Project are the employment training and skills development opportunities with associated benefits to the economy through the multiplier effect. However, the highly specialised wind energy industry and lack of local skills could mean that most the benefits for locals cannot be maximised. The significance is assessed as low positive for all phases of the Project.

The cumulative impacts on tourism are negative and assessed as medium-high.

The cumulative impacts in terms of renewable energy generation are positive and assessed as medium-high, similarly the cumulative impacts on employment and the economy are positive and medium-high.

conclusions and recommendations


The EIA study recommended that landowners sign an agreement indicating they would refrain from grazing livestock in the high and medium sensitivity vegetation areas in the main winter and spring growing and flowering periods (May – October), to facilitate natural rehabilitation.


Further, all feasible areas of high-medium botanical sensitivity as determined by CapeNature (~250ha) should be formally registered as conservation areas with CapeNature’s Stewardship Programme, within one year of project initiation. Associated with this contract will be a requirement for an Environmental Management Plan and environmental auditing to ensure that the rehabilitation and alien vegetation management is adequately carried out.

Bird mortality due to collisions with the turbine blades was assessed as an impact of low-negative significance. However, because the estimated collision rate is a rough indicator of risk, it is necessary to verify this estimate with actual carcass searches on site. These should be done in accordance with the "Best practice guidelines for avian monitoring and impact mitigation at proposed energy development sites in Southern Africa (Jenkins et al, 2011). The frequency of these surveys will be informed by assessments conducted in the initial stages of the monitoring period. Subject to the results of the trials, it is proposed that a site survey is conducted twice a month for an initial minimum period of 12 months. If the results of the monitoring indicate a significant mortality rate for priority species, appropriate mitigation measures would need to be implemented. These could include any or a combination of the following:

Relocation of turbines responsible for particular collision mortality;

  • Halting operation during peak flight periods, or reducing rotor speed, to reduce the risk of collision mortality; and
  • Negotiating appropriate off-set compensation for turbine related collision mortality.

The EIR report found that in terms of cumulative impacts on avifauna, it is imperative that pre-construction and post-construction monitoring  is implemented at all the new proposed sites on the West Coast to establish a baseline, in accordance with the best practice guidelines.

In conclusion, the study found that in comparison to the status quo, the botanical environment would be enhanced mainly through the management of the existing alien vegetation; control of trampling and grazing by livestock; fire management; and conservation of remaining natural vegetation.