Zijin Mining Group, China’s largest gold mining company, shut down operations at its Zijinshan copper mine and hydrometallurgical plant in Fujian province in mid- July after leakage from a wastewater pond on July 3 reached the Ting river and killed thousands of fish—roughly 4.2 million lb, according to a Reuters report.

Zijin reported the leakage had been controlled by July 4 and it had not immediately reported the incident. However, on-going environmental damage sparked outrage, governmental investigation, and the arrest of three Zijin plant managers.

The investigation determined that the leakage was caused by the tearing of the waterproofing layer of the plant’s wastewater pond, leading to a substantial leakage of wastewater into the Ting river through an illegal connection. The investigation found that the heap-leaching sites, pregnant solution pond, barren solution pond, extraction pond, flood control pond, and wastewater pond of the plant had leakage-prevention measures using HDPE padding waterproofing layers. However, as no hardening process had been conducted on the heap-leaching sites and at the base of the ponds, the waterproofing layer was subject to uneven pressure, which led to tearing at the heap-leaching sites and ponds, causing serious leakage.

The investigation determined that monitoring and control of leakage had been inadequate prior the July 3 incident, and as a result, the significance of the incident was not immediately recognized. Zijin was informed on July 15 that the police department of Shanghang county had commenced an investigation in relation to the leakage and that the plant manager, deputy plant manager, and environmental protection officer of the plant had been detained. Zijin reported that it was cooperating with the investigators.

The Zijinshan plant had been scheduled to produce 13,000 mt of copper in 2010.