DBCC CHECKDB firing every 20 - 60 seconds
The reason you are seeing this:

Starting up database 'dbname'
CHECKDB for database 'dbname' finished without errors


Is because you have your database option set for AutoClose.

To turn off AutoClose, do this:

alter database YourDatabase
set auto_close off
go


What AutoClose does is shut down the database after the last user process disconnects.  And then database automatically "reopens" when the next user connection attempts to connect.

Typically it is best practice to keep AutoClose OFF, because of the obvious latency to spin up the database again.  I understand from your question that this is a development environment, but you shouldn't need it there either (and you definitely don't want that in your production environment).

Furthermore DBCC CHECKDB is not actually "firing every 20 - 60 seconds" per the question title, it just appears that way! 

Since SQL Server 2005 the dbi_dbccLastKnownGood value (if present) is reported in the error log every time the database is started. So you are just seeing the same historic information presented repeatedly.

This topic is covered in the article Why is SQL Server running DBCC CHECKDB against my databases at Server Startup?