Is it possible to get the max length of a TEXT field?

I have a text field and want to know if any of the text exceeds 10,000 characters
I can do a select max(len(rtrim(convert(varchar(8000)))) on the field but I'm not able to do for more than 8000 and you can't manipulate TEXT datay type.
Any ideas?
Thanks!SELECT DATALENGTH(Col1) FROM myTable99