Water quality standards at bridge defended
Department says its relaxation of rules for work on bridge to Macau and Zhuhai is reasonable
The environmental watchdog has defended its decision to relax the water quality standards for the Hong Kong section of the bridge linking the city with Zhuhai and Macau, saying that the change is both reasonable and realistic.
The change was approved by the Environmental Protection Department in February last year, but only came to light when the Advisory Council on the Environment cast doubt on it at a meeting last month.
The project's proponent, the Highways Department, and its consultant are now under pressure to file a detailed explanation of the change, and its implications for the bridge's Hong Kong section.
Dr Jonathan Wong Woon-chung, an advisory council member, said environmental officials should also provide more information to ease their concerns.
"Under what conditions can [the change] be initiated? Who has the power to approve it? Is it allowed under the current system?" he asked.
The relaxation was sought by highways officials after the project registered hundreds of incidents of water quality going below pre-set limits during the construction of the section from the western sea border to Scenic Hill in northern Lantau, from October 2012 to March last year.
A confirmed breach of water-quality limits requires the contractor to identify the cause and take remedial action. It could result in a work stoppage.
Contractors have to set up two monitoring stations: an "impact" station near the work site to track the direct water-quality impact from the work; and a "control" station farther away to measure background changes.
Under the revised criteria, there is a breach of water quality only when a measurement exceeds a certain value at the impact station, and if that reading is a certain percentage above the value recorded at the control station at the same time.
Dr Ng Cho-nam, an expert on environmental impact assessments from the University of Hong Kong, said: "The monitoring system is designed to prevent the environment from getting worse; not aiming to penalise contractors but encouraging them to do their best. The change is contrary to this spirit."
A spokeswoman for the Environmental Protection Department said the change was "reasonable" and based on "real-life field experience".
She said in most breaches, the water quality remained well above the historical baseline - an indication that the work had little impact on water quality.