After a nearly 30 hour negotiating session, a tentative agreement was hammered out between the nurses union and SMDC on Wednesday.  That averts a one day strike that was set for next week.  Nurses will vote on the tentative agreement Friday from 6 a-m to 8 p-m at the Coppertop Church.  Meanwhile, nurses from St. Lukes Hospital yesterday overwhelmingly approved a contract that they reached with management last week.