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Defending against monsoons

Hydro International has received the largest orders to date for its Downstream Defender advanced vortex separators, as Kuala Lumpa embarks on an ambitious programme to transform river water quality

Inside a Hydro Downstream Defender showing litter and pollution collected at the top of the unit Inside a Hydro Downstream Defender showing litter and pollution collected at the top of the unit

An ambitious project to clean up Kuala Lumpur’s river system is being aided with stormwater technology from Hydro International, following orders for more than 100 of its Downstream Defender advanced vortex separators.

The vortex separators are being installed at strategic city-centre locations before the outflows of complex network of drains and tributaries discharging into the city’s Klang and Gombak Rivers. Further significant orders are expected in support of the city’s River of Life campaign to transform river water quality.

Kuala Lumpur is situated where the Klang and Gombak rivers meet and literally means muddy confluence. Widespread pollution prompted the Malaysian authorities to launch an ambitious project to improve 110km of the river into a vibrant and liveable waterfront, moving from its current class III-V status (water quality not suitable for body-contact) to a Class IIb river clean enough for recreational use by the year 2020.

Kuala Lumpur has an annual rainfall of nearly 2,400mm with peaks up to 280mm in April and November. Short duration showers can realise 100mm or more in an hour. Urban Malaysia’s typical storm drainage comprises deep road side drains, which discharge into high volume monsoon drains, and eventually into the river.

The tropical Malaysian climate is subject to high flash flow conditions under intense rain storms. The environment also suffers from large amounts of discarded waste such as polystyrene food trays and other packaging, organic pollutants such as food and cooking oil, as well as hydrocarbons.

After storms, the heavy load of silt and trash is visually evident in the rivers.

“Kuala Lumpur has major pollution problems with litter and trash, and also with oils and other hydrocarbons being transported in silts via stormwater into the network of drains and river tributaries which eventually flow in to the River Klang,” says Graeme Fenton, export manager for Hydro International.

“The Downstream Defender was originally developed for more temperate US and UK climates. Installed offline in strategic locations, the Downstream Defender is proving a perfect solution to capturing the large amounts of polluted silts that run off Kuala Lumpur’s highways and for providing “first flush” protection in intense storm conditions.

“In addition to capturing sediments the Downstream Defender is also effective in trapping the large amounts of floatables, such as plastic bottles and polystyrene containers.”

In this context, the ability of the Downstream Defender to concentrate a range of pollutants to a single, accessible location is ideal. The process of maintenance is eased significantly and all performed at ground level using conventional vacuum truck equipment.

The orders are the largest ever made for the Downstream Defender and follow successful trials of the advanced vortex separation technology for the National Hydraulic Research Institute of Malaysia (NAHRIM)*. Conducted by infrastructure and hydrological engineers Weida (M) Bhd, NAHRIM, the study concluded that the Downstream Defender is an effective gross pollutant trap which captured and stored nearly all gross pollutants carried in the storm drain over the trial period.

The Downstream Defender is an approved technology within the Malaysian government’s Manual Sahran Mesra Alam Malaysia (MSMA) which has placed increased emphasis in Malaysia on the need for stormwater control at or near source, and improve run-off quality. 

*NAHRIM: Study on the Effectiveness of the Downstream Defender; November 2010

Topic: Sewer Networks
Tags: Malaysia , rain , pollution , Water Quality , stormwater


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