Dredging in China under strict environmental controls



L.J. Nipius, Boskalis/Hydronamic, Papendrecht, The Netherlands & R. Rijnbeek, CNOOC and Shell Petrochemicals Company Limited, Daya Bay, Huizhou, Guangdong Province, China



CNOOC and Shell Petrochemicals Company Limited (CSPCL) is set to make petrochemicals history in China by building and operating a US$4.3 billion petrochemical complex. The construction of the petrochemicals complex in Daya Bay at the southern coast of China’s Guangdong Province started in 2002. The complex called for the construction of two marine facilities which involved a significant dredging scope of approximately 8 million m3 of clay. The dredging works were undertaken in 2004 by the Nanjing Changjiang Waterway Engineering Bureau in a venture with Boskalis International.

A key requirement of the project was to preserve the sensitive environment in Daya Bay. Therefore all dredging and navigation was to be performed with minimum damage, interference or disturbance to the environment. CSPCL invested in an extensive monitoring programme and mitigating measures to minimise environmental impact.

This paper describes the dredging project, CSPCL’s Sustainable Development strategy, the environmental monitoring activities and the results of the monitoring programme.

Daya Bay dredging project

CNOOC and Shell Petrochemicals Company Limited (CSPCL) is building and operating a US$4.3 billion petrochemicals complex in the Daya Bay Natural Resource Protection Zone. Daya Bay is located at the southern coast of China’s Guangdong Province, some 80 km east of Hong Kong. CSPCL is a 50/50 joint venture between Shell Chemicals and CNOOC Petrochemical Investment Limited.

Construction of the petrochemicals complex started in 2002 and the complex was due to start up late 2005. The complex called for the construction of two marine facilities; a dolphin berth approximately 12 km offshore (Mabianzhou) and a marine terminal nearby the complex (Donglian Harbour).

The dolphin berth at Mabianzhou Island is used to import feedstock for the petrochemical complex and receives ships in the range of 60,000 to 80,000 DWT. The dredging works for the dolphin berth involved the deepening of a berthing area and turning basin to a water depth of approximately 15 metres. Additional imports and product export of the complex takes place through a dedicated jetty adjacent to the complex site on the northern shore of Daya Bay. The construction of this jetty at  Donglian Harbour required dredging of a berthing area, turning basin with connecting area and approach channel to a water depth of approximately 10 metres.

The construction of these two marine facilities involved a significant dredging scope of approximately 8 million m3. The material to be dredged consisted of clay, varying from very soft fat clay to very stiff lean clay. The quantities of material to be dredged for each area are presented in Table I.

The contract for all dredging activities was competitively tendered and awarded in 2003 to the Nanjing Changjiang Waterway Engineering Bureau (NCWEB) in a joint venture with Boskalis Westminster. The NCWEB and Boskalis partnership commenced dredging in Daya Bay early February of 2004.

CSPCL’s sustainable development

CSPCL embodies Sustainable Development (SD) as a key consideration in its activities. Sustainable Development is often defined as ‘Development that meets the needs of the people today without compromising the ability of future generations to meet their own needs’ (Brundtland Commission (1987): ‘Our common Future’). For CSPCL this means that equal consideration is given to the economic, social, and environmental impacts of decisions. SD is embedded in the organisation throughout the lifetime of the complex, both during construction and in the operations phase.

Sustainable development was also a key driver in decision making with respect to the marine construction activities and the dredging activities in particular. Daya Bay is a ‘Natural Resource Protection Zone’. It is a rich spawning ground for a number of commercial fish and shellfish and supports a number of coastal towns.

Prior to a final investment decision being taken by the shareholders, an extensive Environmental and Social Impact Assessment as well as a specific Chinese Marine Environmental Impact Assessment were carried out. The collected detailed information about the state of the surrounding environment acted as inputs into the setting of voluntary standards and guidelines for the marine construction activities. The environmental limits for the dredging activities were based on a combination of Chinese legislation and international standards, such as the World Bank guidelines for port construction.

As part of its commitment to SD, CSPCL maintained an open dialogue with the surrounding communities regarding its activities. Prior to the start of marine construction activities an engagement session was held with all local stakeholders, e.g. fishing villages, seashore villages, and relevant government agencies.

This dialogue continued throughout the entire dredging programme with regular updates being published in CSPCL community newsletters. Maps indicating where the activities would be taking place were published on a regular basis. The results of the independent environmental monitoring for dredging, together with all other environmental monitoring, were published on a quarterly basis through the http://www.cnoocshell.com website.

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