SDB transforms polluted river into an asset

THE clear water of the river sparkles under the late morning light filtering through the trees. Inhaling deeply, you can smell the earth after the light rain and all you can hear is the chirping of insects and the sound of the running stream. It is nature untarnished.

But as the river — Sungai Satu in Penang — flows down the hill of Batu Ferringhi, passing through small villages, a different picture emerges. The water turns cloudy and smells foul. Plastic bags, bottles, pieces of rubbish and a layer of oil and grease can be seen on its surface — hardly an appealing sight.

Property developer Selangor Dredging Bhd (SDB) was well aware of this problem when it acquired a 4.7-acre tract in Batu Ferringhi in 2008 to build its By The Sea development. About 200m of the river flows behind the development, which fronts the sea. From there, the river flows out to the sea.

By The Sea, which has a gross development value of RM230 million, comprises 138 serviced apartment suites, some 56% of which have been taken up to date. With built-ups of 1,030 to 3,038 sq ft, the units are sold at RM1.2 million onwards.

Instead of finding ways to block the sight of the river, SDB opted to turn it into an asset for the development by pumping in RM2 million to rehabilitate it. The task fell to landscape architect Hannah James, associate director of Colin K.

Okashimo and Associates, and environmental consultant and bioengineer Carsten Huttche, director of Enviro Pro Green Innovations (S) Pte Ltd. James, who has worked with SDB on several other projects, including Windows on The Park in Cheras South, Selangor, says, "As with the other SDB projects that we've worked on, we look at the full potential of the site and the natural assets of the area. This project is unique because not only does it have views of the sea, but also a view of a potentially beautiful river and the mountains beyond. It's unique too that the river is not part of the land owned by SDB."

The project kicked off three years ago and the first thing James and Huttche did was to study the river. "There was floating rubbish and even dead animals. The smell was really bad. We were actually told by the locals not to go into the river," recalls James, who designed the master plan of the development.

Huttche, a biologist by training, adds that the amount of rubbish in the river differs from day to day. "Some days are worse than others, especially after the rain." An analysis found the water to be at an unhealthy level of about three to four times the Malaysian standard for recreational waters and its main pollutants were phosphorus, nitrate and ammonia.

Huttche laments the loss of a sense of ownership of the river. "I talked to residents born and raised in the area. The older ones remember playing in the river, they appreciate it and saw the river as an asset. It's interesting that within a generation or so, this sense of ownership was lost.

"One of the major problems is pollution by the upstream stakeholders. It's not just the villagers, but also the hotels, inns and hawkers. There is a drain by the roadside that flows into the river where the tourism stakeholders discharge their waste. We have seen pipes sticking out of some of the houses in the villages where wastewater is discharged. Probably sewer waste as well because we also have microbiological contamination, in this case a high level of E.coli."

Threefold objective

The river rehabilitation is part of SDB's sustainability agenda, which has three objectives: safeguarding the property assets against probable high flood events; improvement of river water quality through a chain of natural treatment methods; and provision of valuable and enjoyable river landscape through innovative bio-engineering methods. The project design was developed in close consultation with the Department of Irrigation and Drainage Penang.

"What we have done is basically reshaped the river by moving the alignment slightly to make space for the treatment wetlands, which are about 800 sq m in total surface area," says Huttche.

The treatment chain starts with a floating boom at the beginning of the 200m stretch. The boom collects floating debris, which will have to be cleared manually on a regular basis. The water then enters the sedimentation forebay where suspended solids are deposited. From there, the water is pumped into the treatment wetlands to remove nutrients and pollutants.

The treated water is then pumped back into the river, clearer and cleaner. The forebay, says Huttche, is a depression in the river that is lined with concrete to keep it stable and allow it to collect sediment. "The plants (19 species) that we have chosen can remove heavy metal, organics and to some degree the microbiological pollutants. I say to some degree because our target is to bring the quality of the water to a level where it's safe for physical contact, but not for drinking. We will not get 100% removal of microbiological contaminants."

Huttche makes it a point to use natural materials for the treatment system as much as possible. One of the exceptions was the pump system. The other materials and technology have been used and tested in river environments in other parts of the world, particularly Germany.

"Bio-engineering and civil engineering have different approaches. To prevent soil erosion, civil engineers will use concrete to build something very rigid. We use chamber rock mattress. This is basically a 2m by 2m non-corrosive net filled with rocks to serve the same purpose," says Huttche. He also uses erosion control blankets, which have a layer of coconut fibre in between. The blankets deflects the rain that causes erosion.

"We used them on the slopes by the river to get enough erosion protection so we can plant the plants. This way, the plants will have a better chance to gain a foothold and not get eroded with heavy rain. Coconut fibre will naturally degrade and the material will only be there for the first year. After that, we should have enough vegetation growing to prevent erosion."

Floods remain a very real concern, especially for rivers with dynamic coastal setting, which Huttche says have the potential to cause flooding. "The residents around the area have told us there has been flooding; the river water has risen to 3m before. One of our objectives is to eliminate or reduce flooding risks."

A stormwater channel was created to serve this purpose. According to Huttche, the size and capacity of the channel was designed to take 1 in 100 years flood event as per the Malaysian guidelines for stormwater management. "Theoretically, based on our calculations, before we built the stormwater channel, the river would have flooded in a 1 in 50 years flood event. When heavy storms come, the water has to bypass the wetlands and flow through to the channel. The water will just be untreated. That's the compromise we have to make. But 90% of the time, we get normal flow."

Creating a balance

For a bioengineer, the main job is to stabilise the environment, make it resistant to floods and to clean the river while landscape architects look at the aesthetic quality. Thus, there is a need to create a balance between a long-term planting strategy and creating an instant greening effect.

"The plants are purposely selected for their stability. Of course, James will come in and say, 'We want it to look good from day one. So, you have to put this plant here and here.' It's a bit of a trade-off. I have to follow some of what she says," Huttche laughs.

The idea, says James, was to blur the lines between the river and the development. "We don't want the river to look like a separate element even though it's actually outside the boundary of the development. We worked on getting the same species of plants inside and outside, so it'll look like the river is just an extension of the development. We also want the residents to see a green river from the day they move in, which means we have to start planting now."

One of the first things James did was to raise the podium 5m to give residents an elevated view of the surroundings. "We want residents to have better views and not on a level where they can only see the trees in front of them. It works well because they will have an uninterrupted view of the sea, the wetlands, the river system, the mountains as well as the pool, which submerges into the sea. It will allow them to appreciate it more."

Some of the common areas are also designed to face the river, such as the gym and the guppy pond as well as a 144m jogging path that goes around the whole development.

"Even though the guppy pond is located within the development, we wanted it to look like an extension of the wetland treatment system — a version children can play in and collect little fishes. We are trying to encourage people to not only have an awareness of what has been done here — the rehabilitation of the river and the efforts to bring wildlife back to the river — but also to enable and encourage them to play in it and appreciate it," remarks James.

Ecological restoration is important to all parties involved in the project. Being a biologist, it is Huttche's personal wish to bring wildlife back to the river. "There is a diverse ecosystem, but due to the condition of the river, only the hardiest species survived. One is the monitor lizard. I've seen a family here. They look like small crocodiles and I saw a baby monitor lizard sunning itself on the rocks the other day. The funny thing about them is that they are not bothered at all by the busy environment."

Looking at the 200m stretch of river after seeing the before photos, the transformation is impressive. The slopes are lined with plants of different shades of green and the water is clear of litter. "In two years, when the development is completed, some of the plants will need thinning. It's quite common in a lot of developments; we put in so many plants and in the long term, we have to thin or take out some of the plants as they will get denser," says James, who expects the plants to become dense in six to nine months.

While not fully commissioned yet, the water treatment system is in working order. "The system is about 90% to 95% completed. We have started testing the water flow, but there is so much pollution in the river. It will take time," says Huttche.

He estimates it will take six months to a year to see the full impact of the water treatment system. SDB will maintain the treatment system once it is fully operational. Even though the treatment system is still in its early days, based on the water samples taken by Huttche, the results are already showing. Rubbish particles, oil and grease can clearly be seen in the untreated water taken upstream while the water taken from the sedimentation forebay is clearer and without the rubbish particles, oil and grease.

Finally, the treated water sample has improved in clarity and colour. The hope is that other parties and the relevant government agencies will pick up from the efforts made by SDB to benefit the larger environment. "It's not just Sungai Satu. There are other rivers here with similar pollution problems. SDB's rehabilitation effort will benefit the water quality downstream and the beach, which is one of the major assets of Batu Ferringhi. We hope efforts won't stop here," says Huttche.


This story first appeared in The Edge weekly edition of May 27-June 2, 2013.