Just to add some documentation on the DUMP function for others that come across this question.
Your issue is interesting. From what all of you have figured out it appears that the column is fine as the dump function is simply showing that the field is a Varchar2 field shown by the output of the dump function - Typ=1. I've pasted below an image of some of the Dump Data Type values I have been able to document.
I've pasted below a nice code snippet to provide examples of working with Oracle's Dump function.
SELECT
DUMP(to_date('15-JAN-18'),10,1,1) AS date_type
, DUMP(123,10,1,1) AS num_type
, DUMP('abc',10,1,1) AS var_or_char_type
FROM dual
;
/* OUTPUT:
|
| "DATE_TYPE" "NUM_TYPE" "VAR_OR_CHAR_TYPE"
|--------------------|-------------------|------------------
| "Typ=13 Len=8: 226" "Typ=2 Len=3: 194" "Typ=96 Len=3: 97"
*/
Basically, locate the entity that is populating this data in this field and fix it at it's source if you want to rid yourself of these strange characters.
