Drainage Services Department - Sustainability Report 2012-2013

Managing the Environment / Resources Conservation

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Sub-sections in Managing the Environment

[Overview of Flood Prevention] [Energy Management and Emission Control] [Resources Conservation] [Green Procurement and Green Office] [Odour Management]

Resources Conservation

Porous Pavement and Rainwater Harvesting at Kowloon City Sewage Pumping Stations

We understand that water is one of the most valuable resources and to make the best use of water resources in the pursuit of our sustainable development, we adopted the most appropriate water conservation measures in our facilities and projects. For example, porous pavement and rainwater harvesting system were installed in 2012-13 at the two sewage pumping stations (SPSs) in Kowloon City which enable extensive green coverage and saving of water for irrigation.

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HDPE Interlocked Reinforced Grass Paver

Porous Pavement

Instead of using the traditional grasscrete, HDPE Interlocked Reinforced Grass Paver was used for paving at the Emergency Vehicular Access (EVA) of the two SPSs in Kowloon City, which enhanced the green coverage of the SPS area and to withstand loading of emergency vehicles.

Rainwater Harvesting

Rainwater Harvesting System was added in the two SPSs to supply rainwater collected on the roofs for irrigation, which reduced the fresh water used for irrigation of the landscape works. The large roof area in two SPSs could be used to collect rainwater for irrigation, and provided an advantage for adopting the rainwater harvesting system.

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Grass planted on Grass Paver at the EVA of SPS No. 1

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Finished Paving Works of Grass Paver at the EVA of SPS No. 1

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Water Feature at SPS No. 1 with water supplied by Rainwater Harvesting System

The following flow program shows the rainwater harvesting system installed in each SPS

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Roof Catchment, Fresh Water Tank, Rainwater Storage Tank, Rainwater Delivery Pump, Sand Filter, UV Sterilizer, Mixing Tank, Rainwater Sensor, To Water Feature, To Irrigation

Rainwater storage tanks were installed to collect the rainwater from the roof. The collected rainwater would be pumped through the rainwater delivery pump to the sand filters. Solid particles would be separated from the filtrated rainwater at the sand filters. The filtrated rainwater would then be sterilised by ultra-violet rays at the steriliser, and would be mixed with the fresh water in the mixing tank. The mixing tank ensured constant supply of water for irrigation from either rainwater or fresh water, with fresh water to be used mainly in dry season when there is less rainfall. The water from the mixing tank would be used for irrigation, and also used for the water feature built in SPS No. 1.

Use of Green Materials/ Products

We are currently using a number of green materials and products during our operations. These include:

Recycled glass cullet as recycled glass block and paving block, pipe bedding materials, ingredients of blinding concrete and porous drainage materials;
Reclaimed water;
Synthetic manhole covers, synthetic gully gratings (both for use in non-vehicular access/area within boundary of Sewage Treatment Works and Pumping Stations) and PVC floor materials, in particular products containing recycled materials; and
Recycled timber.

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