Residents in the area of Anderson Dam over the next few weeks may hear loud warning horns and explosive sounds as crews continue to excavate a tunnel under construction for the dam’s seismic retrofit project, according to Valley Water.  Water district staff say the impact to residents and passing traffic should be minimal.  Starting on Sept. 12, construction crews will begin the controlled blasting of hard rock for the Anderson Dam Tunnel Project. Scheduled detonations over the next few weeks will take place Monday through Friday, and possibly on Saturdays, from 8am-7pm, Valley Water spokesperson Matt Keller said.