[TestMethod]
public void Multi_Sheet_Export_Test()
{
    //Throw in some data
    var datatable = new DataTable("tblData");
    datatable.Columns.AddRange(new[]
    {
        new DataColumn("Col1", typeof (int)), new DataColumn("Col2", typeof (int)), new DataColumn("Col3", typeof (object))
    });

    for (var i = 0; i < 10; i++)
    {
        var row = datatable.NewRow();
        row[0] = i;
        row[1] = i*10;
        row[2] = i%2 == 0 ? "LocationX" : "LocationY";
        datatable.Rows.Add(row);
    }

    //Create a test file
    var fi = new FileInfo(@"c:tempMulti_Sheet_Export.xlsx");
    if (fi.Exists)
        fi.Delete();

    using (var pck = new ExcelPackage(fi))
    {
        var workbook = pck.Workbook;

        var colnames = new List<string[]>
        {
            datatable
                .Columns
                .Cast<DataColumn>()
                .Select(col => col.ColumnName)
                .ToArray()
        };


        var rowgroups = datatable
            .Rows
            .Cast<DataRow>()
            .GroupBy(row => row[2])
            .ToList();


        rowgroups.ForEach(rowgroup =>
        {
            var worksheet = workbook.Worksheets.Add(rowgroup.Key.ToString());
            worksheet.Cells[1, 1].LoadFromArrays(colnames);
            worksheet.Cells[2, 1].LoadFromArrays(rowgroup.Select(row => row.ItemArray));
        });

        pck.Save();
    }

}

var uniqueList = dt.AsEnumerable().Select(x => x.Field<string>("ProdType")).Distinct();
            List<string> myList = new List<string>();
            myList = uniqueList.ToList();

            DataTable[] array = new DataTable[myList.Count()];
            int index = 0;
            foreach (string item in myList)
            {
                var Result = from x in dt.AsEnumerable()
                             where x.Field<string>("ProdType") == item
                             select x;
                DataTable table = Result.CopyToDataTable();
                array[index] = table;

                ExcelWorksheet ws = pck.Workbook.Worksheets.Add(item);
                ws.Cells["A1"].LoadFromDataTable(table, true);
                index++;
            }