Index: DamEngine/trunk/src/Deltares.DamEngine.TestHelpers/Factories/FactoryForSoilProfiles.cs
===================================================================
diff -u -r4835 -r4874
--- DamEngine/trunk/src/Deltares.DamEngine.TestHelpers/Factories/FactoryForSoilProfiles.cs	(.../FactoryForSoilProfiles.cs)	(revision 4835)
+++ DamEngine/trunk/src/Deltares.DamEngine.TestHelpers/Factories/FactoryForSoilProfiles.cs	(.../FactoryForSoilProfiles.cs)	(revision 4874)
@@ -1068,6 +1068,8 @@
         };
 
         SoilProfile2D soilProfile2D = soilSurfaceProfile.ConvertToSoilProfile2D();
+        // Make one boundary not horizontal
+        soilSurfaceProfile.Geometry.Points[4].Z = 0.0;
         return soilProfile2D;
     }
 
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs
===================================================================
diff -u -r4866 -r4874
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs	(.../GeometryData.cs)	(revision 4866)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs	(.../GeometryData.cs)	(revision 4874)
@@ -493,8 +493,8 @@
         {
             SynchronizeLoops();
             RemoveDoublesFromNewlyEffectedPointsAndCurves();
-            Curves.Clear();
-            Points.Clear();
+            // Curves.Clear();
+            // Points.Clear();
             Points.AddRange(NewlyEffectedPoints);
             Curves.AddRange(NewlyEffectedCurves);
 
Index: DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/GeometryHelperTests.cs
===================================================================
diff -u -r4873 -r4874
--- DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/GeometryHelperTests.cs	(.../GeometryHelperTests.cs)	(revision 4873)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geotechnics/GeometryHelperTests.cs	(.../GeometryHelperTests.cs)	(revision 4874)
@@ -23,6 +23,7 @@
 using Deltares.DamEngine.Data.Geometry;
 using Deltares.DamEngine.Data.Geotechnics;
 using Deltares.DamEngine.TestHelpers.Factories;
+using Deltares.DamEngine.TestHelpers.Geometry;
 using NUnit.Framework;
 
 namespace Deltares.DamEngine.Data.Tests.Geotechnics;
@@ -46,9 +47,17 @@
 
         // When
         GeometryHelper.ExtendGeometryLeft(soilProfile2D.Geometry, -2);
+        // For debugging purposes
+        // GeometryExporter.ExportToFile(soilProfile2D.Geometry, visualizationFolder + "Geometry.txt");
+        // GeometryExporter.ExportToJsonFile(soilProfile2D.Geometry, visualizationFolder + "Geometry.json");
 
         // Then
+        var geometryBounds = soilProfile2D.Geometry.GetGeometryBounds();
+        Assert.That(geometryBounds.Left, Is.EqualTo(-2).Within(cTolerance));
         Assert.That(soilProfile2D.Geometry.Left, Is.EqualTo(-2).Within(cTolerance));
+        // At first there are 3 surfaces, but after extending the right boundary, there are 6 surfaces
+        Assert.That(soilProfile2D.Geometry.Surfaces.Count, Is.EqualTo(6));
+        // TOOD: MWDAM-2132 still 3 loose lines
     }
 
     [Test]
@@ -62,20 +71,25 @@
     }
 
     [Test]
-    public void GivenTwoLayerGeometryWhenExtendingRightThenLeftBoundaryIsChanged()
+    public void GivenTwoLayerGeometryWhenExtendingRightThenRightBoundaryIsChanged()
     {
         // Given
         SoilProfile2D soilProfile2D = FactoryForSoilProfiles.CreateSoilProfile2DWithTwoLayers();
 
         // When
-        GeometryHelper.ExtendGeometryRight(soilProfile2D.Geometry, 8);
+        GeometryHelper.ExtendGeometryRight(soilProfile2D.Geometry, 12);
+        // For debugging purposes
+        // GeometryExporter.ExportToFile(soilProfile2D.Geometry, visualizationFolder + "Geometry.txt");
+        // GeometryExporter.ExportToJsonFile(soilProfile2D.Geometry, visualizationFolder + "Geometry.json");
 
         // Then
         Assert.That(soilProfile2D.Geometry.Right, Is.EqualTo(12).Within(cTolerance));
+        // At first there are 3 surfaces, but after extending the right boundary, there are 6 surfaces
+        Assert.That(soilProfile2D.Geometry.Surfaces.Count, Is.EqualTo(6));
     }
 
     [Test]
-    public void GivenTwoLayerGeometryWhenExtendingRightToTheLeftThenExpceptionIsThrown()
+    public void GivenTwoLayerGeometryWhenExtendingRightToTheLeftThenExceptionIsThrown()
     {
         // Given
         SoilProfile2D soilProfile2D = FactoryForSoilProfiles.CreateSoilProfile2DWithTwoLayers();
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryHelper.cs
===================================================================
diff -u -r4873 -r4874
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryHelper.cs	(.../GeometryHelper.cs)	(revision 4873)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryHelper.cs	(.../GeometryHelper.cs)	(revision 4874)
@@ -66,6 +66,7 @@
             }
         }
 
+        geometry.RegenerateGeometry();
         geometry.Rebox();
         geometry.Left = toX;
     }
@@ -109,6 +110,7 @@
             }
         }
 
+        geometry.RegenerateGeometry();
         geometry.Rebox();
         geometry.Right = toX;
     }