Water, Sewage & Effluent May-June 2017 - Page 8

SOUTH AFRICA Laser technology is automating Africa’s future Traditional city modelling practices are starting to give way to new data-driven methods and practices, such as building information modelling (BIM), used to drive down costs and reduce carbon reductions in new urban developments, as well as ensuring future needs are considered in the early planning stages. Says regional general manager Matthew Bester from geospatial technology supplier 3D Laser Mapping, “Successful BIM projects rely on the application of three-dimensional data to accurately measure the structural elements and infrastructure within an urban landscape, including wastewater pipes. Remote sensing is one of the most effective methods of gathering this data,” he says. “Light detection and ranging (LiDAR) based mobile mapping systems allow operators to collect vast amounts of information in the same amount of time it takes to drive around the target area. These measurements are taken by calculating how long it takes a laser beam to be reflected back to the system. When integrated with a localisation system (GNSS) that provides accurate global positioning and an inertial measurement unit (IMU) that measures linear and angular movement, these millions of measurements are combined to create a three-dimensional ‘point cloud’ or visualisation of the area.” Unlike sound and radio waves, light is incapable of passing through solid matter. LiDAR is, therefore, unable to detect underground elements such as sewer pipes; yet, when combined with ground penetrating radar, this technology can map an entire city’s infrastructure precisely and replicate all these elements in three dimensions, all to an accuracy of under 1cm. Bester adds, “A scan provides details of a road’s surface, including markings, defects and manholes, as well as a detailed reconstruction of surrounding features such as built structures, power lines, and even trees and vegetation — all common sights in an urban environment.” Once a scan has been completed, specialist software such as Terrasolid is used to process the data. This turns the millions of collected ‘points’, or returns, into a meaningful geospatial model where features can be enhanced and extracted depending on the results required. “City planners, civil engineers, and construction teams can then use this vital intelligence to plan future works, with more knowledge about the current environment than photos alone would be able to provide. In a wastewater context, this means being able to identify the existence of existing pipework accurately, as well as plan routes and connections for new developments or upgrades to current pipelines,” he says. Mass urbanisation also alters the natural water cycle in emerging suburbs, since once undeveloped areas are now covered with buildings and roads. New planning practices need to be put in place to mitigate the effects of decreased levels of evapotranspiration and increased runoff volumes and rates. Typically, geospatial impact assessments of potential hydrologic effects are based on traditional land management principles that do not adequately address the needs in an urban setting. Datasets collected using such systems can be used to create high-resolution surface terrain models of urban areas. These can then assist with the creation of hydrologic models that tackle sanitation issues, as well as consider environmental considerations such as flooding and urban agriculture.  The uniquely detailed nature of LiDAR data means that it offers great potential for extracting surface information fit for many different applications. The benefit of being able to scan large areas quickly, including densely populated cities and towns, means that the technology is seeing use that is more widespread in urban planning applications, which, in turn, will lead to a future that is more sustainable and planned for all. u 6 Water Sewage & Effluent May/June 2017 Mandela Bay to get mega desalination plant A desalination plant, although expensive to operate owing to high energy requirements, would play a key role in preparing sea water for human consumption through desalination, along with removing other minerals in the process. In the Nelson Mandela Bay region, where water stocks are presently at dire levels, this would provide a new source of potable water. The prospect of establishing the desalination plant in drought-stricken Port Elizabeth has come about through the national government’s Adopt- a-Municipality programme. This involves three major stakeholders in the Bay region — the local authority, beer producer SABMiller, and Marina Sea Salt, whose products are derived from desalinated seawater. According to Annette Lovemore, Nelson Mandela Bay Municipality mayoral committee member for infrastructure and engineering, a meeting with the three role players has already taken place. In support of the venture, she commented that it is a win-win outcome for all stakeholders. The Adopt-a-Municipality programme is driven by the national Department of Cooperative Governance and SABMiller’s agreement, through which the company is about to be renewed. The desalination concept forms part of the new agreement. Lovemore said SABMiller used large quantities of high-quality water to produce its product, and that it was looking for cleaner sources of water, while Marina Sea Salt produced partially desalinated water as a by-product of its salt production. The Nooitgedacht water scheme, still to come online, will give the metro about 50 megalitres of water a day. Since the salt production operation produces about 30 megalitres of water a day, the idea would be to put more water through the salt operations. Lovemore explained that this water, which has already been partially purified, would be further filtered through a desalination plant, in an aim to make it fit for human consumption. Stressing that the project was still at preliminary discussion stage, Lovemore said the Coega Development Corporation (CDC) was also investigating desalination, as it was a water requirement for gas-related initiatives within the Coega Industrial Development Zone. The entire project, inclusive of harvesting desalinated water, is projected to cost USD109.5-million. u The Nooitgedacht water scheme, still to come online, will give the metro about 50 megalitres of water a day.