Exemption on service tax

Dear Experts,

Can you clarify the exemption available on payment of service tax on the works carried out by individual to Mining Company wholly owned by State Government. The work is like check dams, de-Silting Tanks, afferstation works, and works to control the air pollution and is of ecological importance in the locality of mining area. kindly give citation of court if any and rules.

Thanks 

R.S.K.Singh