The script you've posted doesn't even parse.

Msg 102, Level 15, State 1, Line 37

Incorrect syntax near ','.

Msg 134, Level 15, State 1, Line 76

The variable name '@THIS_CALENDAR_YR_START_DT' has already been declared. Variable names must be unique within a query batch or stored procedure.

Msg 102, Level 15, State 1, Line 106

Incorrect syntax near ','.

Msg 156, Level 15, State 1, Line 74

Incorrect syntax near the keyword 'DECLARE'

It uses a lot of log space because you're doing a lot of inserts and deletes. Unless you can figure a way so that you don't need to insert so much and delete so much, you won't be able to do much about the log space.