Be careful of operations that claim to offer yields as high as this, they are always Ponzi schemes. Most reputable mining operations offer yields around 25% - 50% per year, whereas Sierra Hash claims to give a ~3000% which definitely puts it in the Too Good To Be True category.
If you deposit bitcoin with this site, be prepared to lose it.
You can read a full scam report here: https://www.scambitcoin.com/sierrahash/
@SteemCleaners should take a look at this