The ldf file is 'managed' by SQL Server. It's a backup of all the transactions that happen to the database and will keep growing until either a SQL backup is performed (not a Data Pump back) or you manually shrink the database.
If you have SQL Management Studio installed it is fairly straight forward.
1. Stop Data Pump (Full stop Pump, not just stop the service)
2. Use MS Studio to change the Recover Model on DWCHServer to ‘Simple’
3. Shrink the DWCHServer database.
If you don’t have management studio, you should be able to download the Express version for free from Microsoft, but make sure it’s the correct version for you database.
2005 Studio Express will not work with 2008 SQL Server or vice versa.
Also, I believe you need Studio 2008 R2 for Server 2008SP2, even though it is an R1 database.
Other tools are available. Toad from Quest Software is one I’ve heard mentioned but have no experience of. The last time I saw this, the log file shrunk from 64gb to 2mb!