diff --git a/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Properties/ClassPropertiesExtractor.cs b/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Properties/ClassPropertiesExtractor.cs
index 333ac8044..8fd6d7052 100644
--- a/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Properties/ClassPropertiesExtractor.cs
+++ b/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Properties/ClassPropertiesExtractor.cs
@@ -252,11 +252,6 @@ private void ExtractPartProperties(CDB.Part part, Dictionary<string, object?> di
       catchmentProperties["featureLineIds"] = GetSpeckleApplicationIdsFromCollection(site.GetFeatureLineIds());
     }
 
-    if (site.GetParcelIds().Count > 0)
-    {
-      catchmentProperties["parcelIds"] = GetSpeckleApplicationIdsFromCollection(site.GetParcelIds());
-    }
-
     return catchmentProperties;
   }
 
diff --git a/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Raw/AlignmentSubentityArcToSpeckleRawConverter.cs b/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Raw/AlignmentSubentityArcToSpeckleRawConverter.cs
index 5c6d9c563..f7c62dbeb 100644
--- a/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Raw/AlignmentSubentityArcToSpeckleRawConverter.cs
+++ b/Converters/Civil3d/Speckle.Converters.Civil3dShared/ToSpeckle/Raw/AlignmentSubentityArcToSpeckleRawConverter.cs
@@ -1,6 +1,5 @@
 using Speckle.Converters.Common;
 using Speckle.Converters.Common.Objects;
-using Speckle.Sdk;
 
 namespace Speckle.Converters.Civil3dShared.ToSpeckle.Raw;
 
@@ -22,37 +21,30 @@ IConverterSettingsStore<Civil3dConversionSettings> settingsStore
 
   public SOG.Arc Convert(CDB.AlignmentSubEntityArc target)
   {
+    // alignment arcs do not have the same properties as autocad arcs.
+    // we're assuming they are always 2d arcs on the xy plane to calculate the midpoint
     string units = _settingsStore.Current.SpeckleUnits;
 
-    // calculate midpoint of chord as between start and end point
-    AG.Point2d chordMid =
-      new((target.StartPoint.X + target.EndPoint.X) / 2, (target.StartPoint.Y + target.EndPoint.Y) / 2);
-
-    // calculate sagitta as radius minus distance between arc center and chord midpoint
-    double sagitta = target.Radius - target.CenterPoint.GetDistanceTo(chordMid);
-
-    // get unit vector from arc center to chord mid
-    AG.Vector2d midVector = target.CenterPoint.GetVectorTo(chordMid);
-    AG.Vector2d unitMidVector = midVector.DivideBy(midVector.Length);
-
-    // get midpoint of arc by moving chord mid point the length of the sagitta along mid vector
-    // if greater than 180 >, move in other direction of distance radius + radius - sagitta
-    // in the case of an exactly perfect half circle arc...🤷‍♀️
-    AG.Point2d midPoint = chordMid.Add(unitMidVector.MultiplyBy(sagitta));
-    try
+    // calculate the mid vector (center to PI point (intersection of tangents)
+    // note: what is the PI point for a perfect half circle?
+    AG.Point2d piPoint = target.PIPoint;
+    double midVectorX = piPoint.X - target.CenterPoint.X;
+    double midVectorY = piPoint.Y - target.CenterPoint.Y;
+    double midVectorMag = Math.Sqrt(Math.Pow(midVectorX, 2.0) + Math.Pow(midVectorY, 2));
+    double midScalingVectorX = target.Radius * midVectorX / midVectorMag;
+    double midScalingVectorY = target.Radius * midVectorY / midVectorMag;
+    if (target.Delta > Math.PI)
     {
-      if (target.GreaterThan180) // this can throw : The property gets an invalid value according to the entity's constraint type.
-      {
-        midPoint = chordMid.Add(unitMidVector.Negate().MultiplyBy(2 * target.Radius - sagitta));
-      }
+      midScalingVectorX *= -1;
+      midScalingVectorY *= -1;
     }
-    catch (Exception e) when (!e.IsFatal()) { } // continue with original midpoint if GreaterThan180 doesn't apply to this arc
+
+    double midPointX = target.CenterPoint.X + midScalingVectorX;
+    double midPointY = target.CenterPoint.Y + midScalingVectorY;
 
     // find arc plane (normal is in clockwise dir)
     var center3 = new AG.Point3d(target.CenterPoint.X, target.CenterPoint.Y, 0);
-    AG.Plane plane = target.Clockwise
-      ? new AG.Plane(center3, AG.Vector3d.ZAxis.MultiplyBy(-1))
-      : new AG.Plane(center3, AG.Vector3d.ZAxis);
+    AG.Plane plane = new AG.Plane(center3, AG.Vector3d.ZAxis);
 
     // create arc
     SOG.Arc arc =
@@ -74,21 +66,22 @@ public SOG.Arc Convert(CDB.AlignmentSubEntityArc target)
         },
         midPoint = new()
         {
-          x = midPoint.X,
-          y = midPoint.Y,
+          x = midPointX,
+          y = midPointY,
           z = 0,
           units = units
         },
         plane = _planeConverter.Convert(plane),
         radius = target.Radius,
+        angleRadians = target.Delta,
         length = target.Length,
+        units = units,
 
         // additional alignment subentity props
         ["startStation"] = target.StartStation,
         ["endStation"] = target.EndStation,
         ["startDirection"] = target.StartDirection,
         ["endDirection"] = target.EndDirection,
-        ["delta"] = target.Delta,
         ["deflectedAngle"] = target.DeflectedAngle,
         ["minumumRadius"] = target.MinimumRadius
       };