writing all the additions to xml at once

I have a file in xml and I am appending to it - I don't want to append 1 list at a time I want it to write them all then save. I tried putting the xdoc.save outside the foreach loop but I don't think that worked - any ideas?

                        List<InvictusRTDatabase.ChartData> updateList = new List<InvictusRTDatabase.ChartData>();
                        foreach (var s in comparedList)
                        {
                            XDocument xdoc = new XDocument();
                            updateList = irtd.getDifference(Convert.ToInt32(jobID), s.Surveyid);
                            foreach (var item in updateList)
                            {
                                xdoc = XDocument.Load(path + "\\" + jobID + ".xml");
                                XElement Survey = xdoc.Element("Surveys");
                                Survey.Add(new XElement("Survey",
                                           new XElement("SurveyID", item.SurveyID.ToString()),
                                           new XElement("ChartDataUID", item.ChartDataUID.ToString()),
                                           new XElement("ChartDataTime", item.ChartDataTime.ToString()),
                                           new XElement("FilteredDataPoint", item.filteredDataPoint.ToString()),
                                           new XElement("rawDataPoint", item.rawDataPoint.ToString()),
                                           new XElement("Centroid", item.Centroid.ToString()),
                                           new XElement("CentroidOffset", item.CentroidOffset.ToString())
                                           ));
                                xdoc.Save(path + "\\" + jobID + ".xml");
                            }
                           
                        }

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