Works Contract

You can account different contract undertaken by you with the help of AS 7 i.e. Construction Contracts

You can create different ledger accounts giving site names as prefix. This will be bit confusing, since there is number of ledger accounts. Instead you can use create cost centre option in Tally, where you can create site name as Cost Centre. When make the entries, it will be ask for the cost centre to be selected. You can take report cost centre-wise, in your case it is site. However, you have to enable this option in features provided by Tally.