Sustainability Report

DSD has completed several significant projects which are now in full operations during the year, including the Happy Valley Underground Stormwater Storage Scheme and Solar Farm at Siu Ho Wan Sewage Treatment Works. We are committed to improving our drainage and sewage capacity and at the same time introducing innovative elements to our services, with the aim to seek a balance between urban development and environmental protection, so as to promote the sustainability development in Hong Kong and enhance the quality of life of the public. DSD staff has always been a tight-knit team that strategises and strives together, and that has enabled us to overcome every challenge. In this chapter, we are honoured to share our highlights in 2016-17.

Highlights of the Year

Commissioning Ceremony of Happy Valley Underground Stormwater Storage Scheme (HVUSSS)

On 16 March 2017, DSD held the Commissioning Ceremony of HVUSSS and announced the full commissioning of the 60,000 cubic metres (which is equivalent to the total volume of about 24 standard swimming pools) Happy Valley Underground Stormwater Storage Tank. “Smart Drainage • Green Living” is the theme of the Commissioning Ceremony. “Smart Drainage” refers to the innovative design, featuring both of the Movable Weir for more effective stormwater storage and drainage and the largest groundwater and rainwater harvesting system in Hong Kong; “Green Living” refers to the green building designs and the provision of new leisure areas in HVUSSS. On one hand, the underground stormwater storage tank alleviates the flood risk and offers protection to the citizens; and on the other hand, the ancillary facilities above the tank offer a comfortable and relaxing zone for the public.

The construction works for the Scheme commenced in 2012 comprising the construction of a stormwater storage tank underneath the Happy Valley Recreation Ground, a box culvert of about 650 metres long and a stormwater pump house with a peak flow rate of 1.5 cubic metres per second. It will serve as a storage tank to collect and temporarily store the runoff during heavy rainstorms to relieve the discharge load of the downstream drainage system and thereby alleviate flooding risks. The Scheme is divided into two phases. After the commissioning of the project, the flood protection level in Happy Valley and Wan Chai districts will be increased to withstand heavy rainstorms of a 1 in 50-year return period, safeguarding the lives and properties of citizens in the districts. This is also the first flood prevention project in Hong Kong to combine the use of Movable Weir and the Supervisory Control and Data Acquisition (SCADA) System. The Approved Project Estimates for the entire project is about $1.07 billion.

Integrating Sustainability Elements
Innovative Design Achieving Concept of Sponge City

We have continued to explore more sustainable solutions in developing the drainage system to foster environmental and social sustainability and achieve the concept of sponge city. Amongst all, HVUSSS is a good exemplar of such.

Movable Weir

Being the first flood prevention project in Hong Kong to combine the use of Movable Weir and SCADA System, HVUSSS real-time monitors the tidal level and the water level inside the storage tank and the box culvert immediate upstream and downstream of the tank. The positioning of the Movable Weir is based on the real-time monitoring data such that the overflowing of rainwater from the box culvert to the tank can be triggered at the most optimal time, thereby reducing the required design capacity.

When the Black Rainstorm Signal was hoisted on 19 October 2016, the Movable Weir optimized the overflow of rainwater and a total of 27,000 cubic metres of rainwater was collected such that there was no flooding in Happy Valley and its surrounding areas, and the activities at the Happy Valley Racecourse and Recreation Ground could be held as scheduled.

The innovative design can effectively reduce the construction costs and time, thus saving energy consumption to achieve both flood prevention and environmental protection. The design was awarded International Water Association (IWA) Project Innovation Awards (East Asia Regional Awards) and the Hong Kong Institution of Engineers “The Innovation Award for Engineering Industry 2012/13” - Merit Award.

Water Harvesting System

The Stormwater Storage Scheme includes a new water harvesting system that allows groundwater, irrigation water at sport pitches and rainwater to be harvested from subsoil drainage systems that were built underneath the storage tank and sport pitches. These water resources can be used for irrigation, flushing and cleansing after treatment and disinfection to realise the rainwater reuse concept in Sponge City. The system is the largest water harvesting system of the same type in Hong Kong and can conserve precious potable water supply.

Green Lesiure Space

In addition to introducing green building features such as environmentally friendly permeable paving blocks and solar panels in the Stormwater Storage Scheme, we have improved the public leisure area in the Happy Valley Recreation Ground. For instance, a green lawn has been built on the pump house rooftop to serve the purpose of heat insulation and providing a scenic lookout for the public. Also, we changed the traditional box-shaped structural form of the fan room and optimised it by including a canopy design so that the public can rest comfortably outside the fan room in all weather conditions. The fan room and pump house have obtained Platinum Rating of Provisional Assessment under the BEAM plus (New Buildings) from the Hong Kong Green Building Council.

Enhance Cost Effectiveness with the Adoption of New Engineering Contract (NEC)

HVUSSS is the current largest NEC project of DSD. NEC emphasises the mutual trust and cooperation between the employer and contractor in project management, and there is a collaborative risk management mechanism to resolve construction risks at early stage. Since the commencement of the HVUSSS, we have adopted the “One Team · One Goal” spirit to implement the project. The project was commenced in September 2012 and scheduled for completion by the end of 2018. With the collaboration and efforts made by various parties, the project was completed one year ahead of the schedule with about $90 million saving in project cost.

Public Engagement

We have organised a number of public engagement activities, including carnivals, group visits, media interviews and community outreach programme to promote the HVUSSS and to enhance the public understanding of the project.

Green Carnival of HVUSSS

To promote an interactive and direct communication with the public and to introduce the community the new leisure facilities in the Happy Valley Recreation Ground, we jointly organised a Green Carnival with the Wan Chai District Council, Leisure and Cultural Services Department and Wan Chai District Office on 5 November 2016. In addition to displaying the engineering model, there was a variety of game booths and performance in the Carnival. In a short span of 3.5 hours of the Carnival we already received more than 2,100 citizens. The active participation of nearby schools, Hong Kong Jockey Club and Hong Kong Football Club, contributed to a more enjoyable Carnival.

Technical Visits

Over the past year, a number of overseas and local organisations have visited the HVUSSS site, including the Indonesian Government, the Building and Construction Authority of Singapore Government, Bureau of Water Resources of Shenzhen Municipality, the Business Environment Council, the Institution of Civil Engineers, the Hong Kong Institution of Engineers, the Hong Kong Institute of Surveyors and other academic and community groups.

Media and Community Promotion

The project team has received different media interviews in the past year, including Phoenix Television, Xinhua News Agency, China Central Television and U Magazine, etc. The interviews introduced the “Three-pronged flood prevention” strategies, i.e. stormwater interception, flood storage, and drainage improvement, as well as the innovative elements and features of the HVUSSS, including the Movable Weir, water harvesting system and green design features. For more details, please refer to Chapter 7 Media Engagement Activities.

We have also enhanced public and stakeholders' understanding of the project through the dissemination of newsletters and participation in different kinds of community activities.