Hi i currently have a auto sprinler system installed...im gona have someone put in all new pvc piping and all new heads in the rear yard? i have a avg size rear yard(single family home) with about 17 heads....whats the ball park cost for just diggin a trench and putting in all new pvc pipe with approx 17 sprinkler heads.so basically parts and labor for the things mentioned above? im not replacing the controller or the valves.