THE Government is to build a temporary site for mid-stream container carriers despite opposition from the public and some of its own departments. About 12 hectares of Tsing Yi sea-front land now occupied by the mid-stream operators - boats which unload cargo from larger ocean-going vessels - for the handling and storage of containers will be cleared towards the end of this year for development of Container Terminal No 9. The Government will offer a one-year tenancy to relocate mid-stream operators to Area 16 of Tuen Mun, originally earmarked for a sports stadium. The Environmental Protection Department and the Fire Services Department had opposed the idea and the Transport Department had strong reservations it would worsen already crowded traffic on Tuen Mun Road. Tuen Mun District Board has also strongly objected to the proposals. But the two branches responsible for the project - the Planning, Environment and Lands Branch and the Economic Services Branch - both declared it was the only choice available. ''In the short term, a site at Area 16, Tuen Mun, has been identified as the only possible additional location for temporary container handling which will become available. Failure to secure its use will reduce port capacity at a time of increasing demand,'' the Economic Services Branch said in a paper presented to the Legislative Council.