Ambuja Cement Eastern (ACEL), a subsidiary of Holcim, is planning to invest Rs 115 crore for setting up a one million tonne per annum greenfield plant in West Bengal.Harsh Neotia, managing director of ACEL, said: "The new plant would come up at Farakka in Murshidabad district, and would utilise fly ash from NTPC's super thermal power plant located there.The construction of the greenfield plant is scheduled to commence in December while the unit is expected to come on stream during the middle of 2006.ACEL has already set up a one million tonne plant at Sankrail in Howrah district.