An Environmental Impact Assessment/Biodiversity Study was commissioned to evaluate the environmental impact of the proposed upgrading of a facility within Chestnut Avenue Waterworks (CAWW).

The CAWW is located on the western side of the Central Catchment Nature Reserve where it is bounded by Pierce Reservoir in the east and by secondary forests in the north, west, and south. These secondary forests are mature and primary forest remnants could be impacted by the upgrading works through edge effects or forest fragmentation. To safeguard the Reserve and forests, SECS was brought on to assess the current state of the environment and propose measures to mitigate any adverse impacts on environmentally sensitive areas.

The Central Catchment Reserve is Singapore’s largest Nature Reserve, covering over 2,000 hectares and home to some of the richest forests in terms of biodiversity.

The forest here comprises mainly of dipterocarp – a family of hardwood, tropical trees that are recognized by their winged seeds. Dipterocarps are among the tallest trees in the world – a trait that has led to over-felling for timber, and has resulted in several species becoming endangered.

Key Facts

• Forest reserves make up 5% of Singapore’s land, but harbour over 50% of the native biodiversity.
• Many endangered and threatened species persist in Singapore’s forests, including the Sunda Pangolin (manis javanica) and the Blue-rumped Parrot (psittinus cyanurus).

To develop a holistic picture of the environment surrounding the CAWW, we conducted a battery of studies including:

• Biodiversity Impact Assessment

Field surveys for both flora and fauna were conducted. Observed species were categorized primarily by their national conservation status, and secondarily by their international conservation status.

Areas where species of conservational value were identified were then identified as “hotspots” and measured by proximity to the CAWW upgrading works.

• Tree Mapping and Inventory

Trees that could be affected during construction were identified by a certified arborist before being mapped out and categorized.

• Water Quality Study

Both in-situ and ex-situ water quality studies were conducted on the streams within the Reserve. The water was also tested for heavy metals and other potential contaminants.

• Sediment Quality Study

A sediment quality study was conducted to identify the baseline sediment conditions of the soil near the upgrading area. This was to ensure better precautions could be taken to handle construction erosion.

• Noise and Ambient Dust Monitoring Study

Noise and dust measurements were taken around the CAWW to establish whether the noise and dust generated by construction activities would have an impact on the surrounding ecosystem.

By integrating the findings from the various studies, we were able to predict the environmental impacts of the proposed project and develop measures to mitigate any damage to ecological habitats.