public string VcsWkt {get; set;}

// Use a builder convenience method or use a builder constructor.

// see a list of vertical coordinate systems at http://resources.arcgis.com/en/help/arcgis-rest-api/index.html#/Vertical_coordinate_systems/02r3000000rn000000/

// Builder convenience methods don't need to run on the MCT.
// 4326 = GCS_WGS_1984
// 115700 = vertical WGS_1984
SpatialReference sr4326_115700 = SpatialReferenceBuilder.CreateSpatialReference(4326, 115700);

// SpatialReferenceBuilder constructors need to run on the MCT.
ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
{
  using (SpatialReferenceBuilder sb = new SpatialReferenceBuilder(4326, 115700))
  {
    // SpatialReferenceBuilder properties
    //   sb.wkid == 4326
    //   sb.Wkt == "GEOGCS["MyGCS84",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT[\"Radian\",1.0]]"
    //   sb.name == GCS_WGS_1984
    //   sb.vcsWkid == 115700
    //   sb.VcsWkt == "VERTCS["WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PARAMETER["Vertical_Shift",0.0],PARAMETER["Direction",1.0],UNIT["Meter",1.0]]

    // do something with the builder

    sr4326_115700 = sb.ToSpatialReference();
  }
});