Guest guest Posted December 3, 2002 Report Share Posted December 3, 2002 ***************************Advertisement*************************** eCentral - Your Entertainment Guide http://www.star-ecentral.com ***************************************************************** This message was forwarded to you by yitzeling. Comment from sender: This article is from thestar.com.my URL: http://thestar.com.my/lifestyle/story.asp?file=/2002/12/3/features/lislope & sec=f\ eatures ________________________ Tuesday, December 03, 2002 Checking erosion By TAN CHENG LI THERE & #8217;S an exposed slope behind your house. You shield it with a brick wall or a rubble wall made up of rocks bonded with mortar. It & #8217;s a common practice everywhere. But president of the Institute of Engineers Malaysia (IEM) Dr Gue See Sew has this advice: “Don & #8217;t do that. It & #8217;s very dangerous.” Gue says simple brick and rubble walls are not slope-retaining walls and thus offer little protection against erosion and slope failures. A proper slope protection wall is one that is “engineered.” That means the wall must be properly planned, designed, constructed and maintained. These are the elements which will either make or break a slope-retaining wall. A lack of these four factors is the main cause of crumbling slopes, says Gue. This is seen in the landslide which flattened the double-storey residence of former Armed Forces chief Jen Tan Sri Ismail Omar in Taman Hillview in Hulu Klang, Selangor, on Nov 20, killing eight, including six of Ismail & #8217;s family members. According to Gue, a member of the inquiry team investigating the entire area around Taman Hillview and the Highland Towers, checks show that an unstable rubble wall and poor drainage on the slope were the culprits. The wall, one of 13 which run the length of the slope above Ismail & #8217;s residence and the Highland Towers, is believed to have been put up around 1985 when the area was developed. Gue says the walls were neither engineered nor built with adequate safety features. They lacked a wider base and narrower top, which are the standard specifications for wall stability. Incomplete drainage channels worsen the situation as run-off flows changed course. So when heavy rains raised the ground water level behind the rubble wall above Ismail & #8217;s residence, the structure failed to withstand the increased pressure. It collapsed, triggering an avalanche of mud, rocks and vegetation. “Rains always get blamed but it & #8217;s only a triggering mechanism,” says Gue. To ensure safer slopes in the future, an IEM-led committee has proposed that the Housing and Local Government Ministry set up a Hillsite Engineering Agency (HEA). This body will assist local authorities in regulating and evaluating all proposed hillside developments. Since local authorities often lack expertise and manpower, the agency will plug the gap by assessing slope protection measures for hillside projects. Engineered slopes should be designed by taking into consideration ground water, soil properties, geometry of slopes, drainage systems and features of adjacent slopes. The proposal is included in a position paper for mitigating the risk of landslide on hillside development, drawn up over two years by the committee which consist of experts from the ministry, universities and the private sector. The report was submitted to the Science, Technology and Environment Ministry in April and is expected to be presented to the Cabinet for the next course of action. <b>Giving legal bite</b> The IEM report also highlighted the lack of legislations and guidelines to avert landslides and slope failures. Though Environmental Impact Assessments are now mandatory for highland projects, Gue says the reports stress on environmental aspects and not design of slopes. Similarly, geological reports talk only about the geology of the site and exclude slope design and slope stability. While the proposed HEA will check on future hillside development, existing hillside projects must also be scrutinised to ensure their safety. The IEM proposed that local authorities be given legal power to issue a “Dangerous Hillside Order” to owners of doubtful and unstable slopes. The land owner will then have to engage engineers to investigate and strengthen the slopes. Currently there is no such legal provision. If the land owner refuses to act, one option is for the Government or local authority to foot the bill and vacate the land. Those keen on developing the site later on will pay a penalty for the work and supervision shouldered by the Government. This is the practice in Hong Kong. In fact, much can be learnt from Hong Kong which has been successful in mitigating landslides and slope failures. Furthermore, its granitic formation and steep slopes are similar to the landslide-prone area of Hulu Klang. Hong Kong has forked out HK$600mil (RM295.2mil) annually since 1997 to strengthen weak hill slopes. A central slope policing body was created in 1977 after two catastrophic landslides in 1972 and 1976. This body regulates the whole process of investigation, design, construction, monitoring and maintenance of slopes. Since its set-up, landslip fatality had dropped ten-fold. To better manage hillside development, the IEM recommended classifying slopes according to risk levels. The grouping will be based on the geometry of slopes such as height and angle. Each category will be subjected to differing levels of scrutiny and requirements. Development on Class 1 (low-risk) slopes will need to comply only with existing laws. Those in Class 2 will need to submit a geotechnical report to the HEA, while those in Class 3 will require a geotechnical report and the appointment of an accredited checker to vet the adequacy of design and safety of the development. It is recommended that the Board of Engineers carry out registration of the accredited checker to ensure that only experienced and qualified engineers are engaged for hillside development projects. To be registered, the checker must have at least 10 years of relevant experience. With the three steps & #8211; slope classification, Dangerous Hillside Order and slope evaluation by checkers & #8211; Gue believes hillsides can be made stable and a safe place to live. He asserts that staying away from hilly sites is not the answer. Thus he disagrees with the Cabinet guidelines on highland development which prohibits development on slopes with gradients exceeding 35 degrees. Gues says the guidelines merely imposed a blanket ban and do not address the issue of slope stability. If there are dwellings at the foot of a steep slope, he says the slope should be stabilised to prevent landslides rather than left as it is. “Untouched or natural slopes do not equal stable slopes,” he says. Local authorities should also follow in the footsteps of Cameron Highlands which has made a geotechnical and soil erosion assessment report mandatory for all projects. Soil erosion research consultant Tew Kia Hui says this assessment will identify erosion-prone areas and the measures to be taken during construction to check erosion which may lead to slope failures. The tests will cover areas such as soil type and properties, groundwater level, slope stability, erosion risks and mapping of erodable sites. <b>Keeping watch</b> While new hillside projects are bound by more stringent rules and have the benefit of improved knowhow on slope protection, there is not much that can be done for the older developments & #8211; except to monitor these sites for tell-tale signs of erosion and landslides, and then take remedial measures. But who is responsible for keeping an eye? In the case of Ulu Klang, already notorious as a landslide prone area, the Ampang Jaya Municipal Council (MPAJ) has to abide by its promise (made after two major landslides in Bukit Antarabangsa in May 1999) to set up a task force to monitor slopes in the area. It was also reported that complaints from residents of Taman Hillview & #8211; including Ismail himself & #8211; on erosions and landslips in the area had gone unheeded. Now what is lacking is long-term maintenance and protection of slopes. “Even a properly built slope, if not maintained, can fail,” says Gue. Regular inspections are vital to detect earth movements or changes in drainage patterns early on. Many slopes fail because of blocked or inadequate drainage systems. Unfortunately, developers have nothing to do with maintenance of the drainage once a project is completed. It is the job of local authorities which always claim to be short of trained staff and funds. It & #8217;s worst in the case of abandoned hillside projects as no one will be checking for cracks in retaining walls and blockages in drainage systems. Case in point: the cleared piece of land above Taman Hillview. The hill was cut in the 1980s by Highlands Properties for the construction of 50 bungalows but the project stalled due to the recession. (When the company defaulted in its loan repayment, ownership of the property went to the financier Arab Malaysian Finance Bhd.) Many may be aghast at the thought but Gue reasons that it may be better to develop the area if only to guarantee proper design, drainage and maintenance. “If there is no development, nobody will take care of it.” He says the immediate action should be to replace the unstable rubble walls and strengthen the slopes in Taman Hillview. “More landslides cannot be ruled out. In the medium term, the authorities should investigate the surrounding area, particularly sites with evidence of previous slips. That & #8217;s the sensible thing to do.” That area should include Bukit Antarabangsa, which straddles the mountain range behind Taman Hillview. The residential area is riddled with landslips and fallen slopes. There are also plenty of abandoned link houses and condominiums. Perched precariously on steep slopes, it is no wonder that these projects were discontinued. But the biggest abandoned project there has to be that of Bukit Perdana. A huge chunk of the Gombak Forest Reserve was degazetted for this exclusive bungalow lot project in the early 1990s. At the height of the earthworks, trails of red earth criss-crossed this highland that is connected to the hill range behind Highland Towers and Taman Hillview. The project stalled after a stop-work order was issued by the Department of Environment. Recommendations to rehabilitate the site by planting fast-growing trees were left unheeded. Carved up and left exposed to the erosive forces of nature, the area today is full of landslides and gullies. Streams, diverted during initial earthworks but left unattended for years, have now found their own flow, and broken up roads and drains in the process. As has been proven time and again, hilly lands which have been tampered with but deserted may yet pose the greatest threat.<p> ________________________ Your one-stop information portal: The Star Online http://thestar.com.my http://biz.thestar.com.my http://classifieds.thestar.com.my http://cards.thestar.com.my http://search.thestar.com.my http://star-motoring.com http://star-space.com http://star-jobs.com http://star-ecentral.com http://star-techcentral.com 1995-2002 Star Publications (Malaysia) Bhd. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of Star Publications is prohibited. Quote Link to comment Share on other sites More sharing options...
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