OVER A HUNDRED EMPLOYEES AT THE SALINAS VALLEY MEMORIAL HOSPITAL ARE FACING LAYOFFS.    HOSPITAL OFFICIALS CONTACTED THE CALIFORNIA NURSES ASSOCIATION LAST WEEK, SAYING IT PLANNED TO MAKE CUT-BACKS AND ELIMINATE STAFF POSITIONS.     THE NURSES UNION PLANS TO PICKET TOMORROW (THURS) TO PROTEST THE PLAN AS WELL AS THE HOSPITAL CEO’S RECENT 6-FIGURE RAISE.     SVMH OFFICIALS ARE MOVING FORWARD WITH PLAN STATING 75% OF ITS NURSING STAFF ARE PART-TIME EMPLOYEES RECEIVING FULL-TIME BENEFITS.     CONTRACT NEGOTIATIONS ARE SCHEDULED TO BEGIN NEXT MONTH.