QINGDAO, July 9 (Xinhua) -- Workers are racing against the time to build the second barrier to prevent algae from invading the Olympic sailing venue off the coast of Qingdao city in east China's Shandong Province.

    Since the end of last month, more than 1,400 people have been working to erect the barrier, which is 100 meters from the first barrier and will extend 16,000 meters.

    The barrier is composed of a specially-developed floating net, which measures 200 meters long and two meters wide. Attached to the net are 150 buoys, each with a diameter of 30 centimeters.

    The barrier is fixed by anchors and H-shaped concrete blocks.

    Workers have already completed 8,000 meters of the barrier and is working on the remaining 8,000 meters.

    Local officials said the method had been proved very effective.

    As of Wednesday, only 2.8 percent of the 49.48-square-kilometerguarded sailing venue was covered by algae, a sharp drop from 32 percent when it appeared off the coast in early June.

    The Qingdao government has vowed to clear up the venue before July 15.

    The sailing competitions are scheduled from Aug. 9-23.

    On Wednesday, 81 boats from 26 countries practiced sailing in the area. There are 399 sailing athletes from 34 nations being trained.