string strQuery = @"<Where>
                       <Leq>
                          <FieldRef Name='RemediationDate' />
                          <Value Type='DateTime'><Today OffsetDays='30' /></Value>
                       </Leq>
                    </Where>";

var query = new SPQuery
{
   Query = strQuery
};

var scheduledItems = spList.GetItems(query);
foreach (SPListItem item in scheduledItems)
{
  //send email, update item status
}