22 Apr 2021

Innovative rainwater storage system goes down a storm

Binnies Hong Kong has used its technical expertise to solve the historical flooding problem in Happy Valley, Hong Kong. During the rainy season, heavy rainstorms and downpours had led to floods up to one metre deep in some areas, but an innovative stormwater storage scheme is now helping to combat the situation. 

The three-pronged flood prevention strategy has been introduced by the Hong Kong government’s Drainage Services Department (DSD) to help combat flooding during the rainy season. Intended to help relieve pressure on the overwhelmed drainage systems, the strategy involves stormwater interception by drainage tunnels, temporary storage of stormwater in underground stormwater storage tanks in the midstream and local pipe upgrading works. 

“Almost 20 years ago, Binnies Hong Kong completed the first large-scale underground storage tank in Hong Kong, at Tai Hang Tung, for temporary storage of stormwater during heavy rainstorms,” explains Binnies Hong Kong Managing Director, Andy Kwok. “With a storage capacity of 100,000 m3, the system effectively reduced flooding in Mong Kok, which is one of the busiest districts in the world. A major achievement was to cut back the length of drains to be upgraded from 94 km to around 48 km; these were laid under very busy roads with congestion of utilities and complex project interfaces. 

“More recently, we designed a 2.4 hectare, 60,000 m3 storage tank at Happy Valley. This storage system featured innovative designs, including a movable weir system, a foundation design with a peripheral sheet pile wall and subsoil drainage system and a water harvesting system. The robust nature of this scheme effectively reduced the required volume of the storage tank by 25% and shortened the construction time, thus minimising public and environmental impacts.” 

Innovative rainwater storage system goes down a storm

Speaking to the Institution of Civil Engineers (ICE) in a video about the Happy Valley underground stormwater storage scheme, Andy added, “The movable weir system enables excess stormwater to enter the tank at the optimal time and also enables the discharge of part of the stored stormwater back to the box culvert by gravity, instead of pumping, to achieve an energy saving.” 

The construction of the Happy Valley underground stormwater scheme was divided into two phases commissioned in 2015 and 2017, respectively. Over the years, the scheme has been performing as designed, to safeguard the general public from flood risk.

The construction of the Happy Valley underground stormwater scheme

You can view the full video explaining the scheme on the ICE website. 

About Binnies

At Binnies, we create new possibilities for humanity through our innovative approach to delivery. Backed by a culture that has stayed true since the company’s founding over 100 years ago, Binnies develops intelligent water and environmental solutions using a whole-life-cycle approach to deliver functional infrastructure and lasting environmental and social legacies. We strive to elevate the quality of life for our local communities today and for generations to come.

Binnies is an RSK group company and was formerly part of Black & Veatch.

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About the RSK group (RSK)

RSK is a leading integrated environmental, engineering and technical services group made up of over 100 businesses. The group is headquartered in the United Kingdom and has an established presence in more than 40 countries around the world.

For over 30 years, RSK has been helping organisations realise their business goals efficiently, cost-effectively and with the minimum environmental and social impact. We deliver practical solutions to some of the greatest challenges of our time. As a client-focused business, our services are constantly evolving to directly respond to or pre-empt global conditions and legislative drivers.

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Media contacts

Binnies Hong Kong

Andrea Tang Tel: +852 2608 7647 | Mobile: +852 6193 2020 | Email: tangys@binnies.com