Authentic Independent Union representative Iván Vargas Muñiz (Facebook via Iván Vargas Muñiz) By THE STAR STAFF The Authentic Independent Union (UIA by its initials in Spanish),  which represents employees of the Puerto Rico Aqueduct and Sewer Authority (PRASA), announced Tuesday that its members will halt work today and Thursday after failing to secure a long‑sought salary increase. UIA representative Iván Vargas Muñiz said the stoppage comes in response to what the union describes as...