The previous mark held by Mattie Moncayo was 18 : 07 .
Clairmonte 's personal record was an 18 : 11 set a week earlier in winning the Division II race at the nationally renowned Tiffin Carnival .
The previous mark held by Mattie Moncayo was 18 : 07 , and Clairmonte 's personal record was an 18 : 11 set a week earlier in winning the Division II race at the nationally renowned Tiffin Carnival .