In September of last year I had 5 of these planted and they looked great all winter. This spring they started turning brown and my Landscsper kept telling me they were supposed to do that and would every summer but come back in the winter. I have a sprinkler system so I know they're getting plenty of water but now they are completely brown and look dead. Is this normal?

Evergreens are supposed to be green year round. They may suffer some tip burn or needle discoloration from the winter weather in some years. If there is a warranty involved, work with your landscaper to resolve this. In general sprinkler systems are designed for irrigating lawns and unless your system is zoned properly and or you have regulated the volume of water iin some manor, you want to be sure they are not getting too much water. If you are able to dig one of the plants up carefully then you can examine the root system. New roots should have/been growing from the older roots. If the soil is wet and heavy or you see watering present in the hole, then very likely they drowned.