Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/PresentationObjects/RingtoetsPipingSurfaceLinesContext.cs
===================================================================
diff -u -r065af7e201b59ec19a17c42e9d772f5e86b31338 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/PresentationObjects/RingtoetsPipingSurfaceLinesContext.cs	(.../RingtoetsPipingSurfaceLinesContext.cs)	(revision 065af7e201b59ec19a17c42e9d772f5e86b31338)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/PresentationObjects/RingtoetsPipingSurfaceLinesContext.cs	(.../RingtoetsPipingSurfaceLinesContext.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -37,22 +37,32 @@
         /// Creates a new instance of <see cref="RingtoetsPipingSurfaceLinesContext"/>.
         /// </summary>
         /// <param name="surfaceLines">The collection to update.</param>
+        /// <param name="failureMechanism">The failure mechanism</param>
         /// <param name="assessmentSection">The assessment section.</param>
         /// <exception cref="ArgumentNullException">Thrown when any input argument is <c>null</c>.</exception>
-        public RingtoetsPipingSurfaceLinesContext(ObservableList<RingtoetsPipingSurfaceLine> surfaceLines, IAssessmentSection assessmentSection)
+        public RingtoetsPipingSurfaceLinesContext(ObservableList<RingtoetsPipingSurfaceLine> surfaceLines, 
+            PipingFailureMechanism failureMechanism, 
+            IAssessmentSection assessmentSection)
             : base(surfaceLines)
         {
             if (assessmentSection == null)
             {
                 throw new ArgumentNullException("assessmentSection");
             }
+            if (failureMechanism == null)
+            {
+                throw new ArgumentNullException("failureMechanism");
+            }
 
             AssessmentSection = assessmentSection;
+            FailureMechanism = failureMechanism;
         }
 
         /// <summary>
         /// Gets the assessment section which the context belongs to.
         /// </summary>
         public IAssessmentSection AssessmentSection { get; private set; }
+
+        public PipingFailureMechanism FailureMechanism { get; private set; }
     }
 }
\ No newline at end of file
Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs
===================================================================
diff -u -r71144e484518b806157fb6613779981342542462 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 71144e484518b806157fb6613779981342542462)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -39,6 +39,7 @@
     {
         private readonly Observer failureMechanismObserver;
         private readonly Observer assessmentSectionObserver;
+        private readonly Observer surfaceLinesObserver;
         private readonly Observer stochasticSoilModelsObserver;
 
         private readonly MapLineData referenceLineMapData;
@@ -60,6 +61,7 @@
 
             failureMechanismObserver = new Observer(UpdateMapData);
             assessmentSectionObserver = new Observer(UpdateMapData);
+            surfaceLinesObserver = new Observer(UpdateMapData);
             stochasticSoilModelsObserver = new Observer(UpdateMapData);
 
             referenceLineMapData = RingtoetsMapDataFactory.CreateReferenceLineMapData();
@@ -95,6 +97,7 @@
                 {
                     failureMechanismObserver.Observable = null;
                     assessmentSectionObserver.Observable = null;
+                    surfaceLinesObserver.Observable = null;
                     stochasticSoilModelsObserver.Observable = null;
 
                     Map.ResetMapData();
@@ -103,6 +106,7 @@
 
                 failureMechanismObserver.Observable = data.WrappedData;
                 assessmentSectionObserver.Observable = data.Parent;
+                surfaceLinesObserver.Observable = data.WrappedData.SurfaceLines;
                 stochasticSoilModelsObserver.Observable = data.WrappedData.StochasticSoilModels;
 
                 UpdateMapData();
Index: Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs
===================================================================
diff -u -rf70611f9af51a6ffc8cb4d8d28d1ea806104937b -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision f70611f9af51a6ffc8cb4d8d28d1ea806104937b)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -24,6 +24,7 @@
 using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;
+using Core.Common.Base;
 using Core.Common.Controls.TreeView;
 using Core.Common.Gui.ContextMenu;
 using Core.Common.Gui.Forms;
@@ -217,7 +218,10 @@
                 Image = pipingSurfaceLine => PipingFormsResources.PipingSurfaceLineIcon,
                 ContextMenuStrip = (nodeData, parentData, treeViewControl) => Gui.Get(nodeData, treeViewControl)
                                                                                  .AddPropertiesItem()
-                                                                                 .Build()
+                                                                                 .AddDeleteItem()
+                                                                                 .Build(),
+                CanRemove = (nodeData, parentData) => true,
+                OnNodeRemoved = OnSurfaceLineRemoved
             };
 
             yield return new TreeNodeInfo<StochasticSoilModelsContext>
@@ -460,6 +464,33 @@
                     .ToList());
         }
 
+        #region RingtoetsPipingSurfaceLine TreeNodeInfo
+
+        private void OnSurfaceLineRemoved(RingtoetsPipingSurfaceLine nodeData, object parentData)
+        {
+            var context = (RingtoetsPipingSurfaceLinesContext) parentData;
+            var changedObservables = new List<IObservable>();
+            PipingFailureMechanism failureMechanism = context.FailureMechanism;
+            foreach (PipingCalculationScenario pipingCalculationScenario in failureMechanism.Calculations)
+            {
+                if (ReferenceEquals(pipingCalculationScenario.InputParameters.SurfaceLine, nodeData))
+                {
+                    pipingCalculationScenario.InputParameters.SurfaceLine = null;
+                    changedObservables.Add(pipingCalculationScenario.InputParameters);
+                }
+            }
+
+            context.WrappedData.Remove(nodeData);
+            changedObservables.Add(context.WrappedData);
+
+            foreach (IObservable observable in changedObservables)
+            {
+                observable.NotifyObservers();
+            }
+        }
+
+        #endregion
+
         # region Piping TreeNodeInfo
 
         private ContextMenuStrip FailureMechanismEnabledContextMenuStrip(PipingFailureMechanismContext pipingFailureMechanismContext, object parentData, TreeViewControl treeViewControl)
@@ -533,7 +564,7 @@
             return new ArrayList
             {
                 new FailureMechanismSectionsContext(failureMechanism, assessmentSection),
-                new RingtoetsPipingSurfaceLinesContext(failureMechanism.SurfaceLines, assessmentSection),
+                new RingtoetsPipingSurfaceLinesContext(failureMechanism.SurfaceLines, failureMechanism, assessmentSection),
                 new StochasticSoilModelsContext(failureMechanism.StochasticSoilModels, failureMechanism, assessmentSection),
                 new CommentContext<ICommentable>(failureMechanism)
             };
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PresentationObjects/RingtoetsPipingSurfaceLinesContextTest.cs
===================================================================
diff -u -r62d6426f4dc874b8e74a0c3ebe4c3491fa207af1 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PresentationObjects/RingtoetsPipingSurfaceLinesContextTest.cs	(.../RingtoetsPipingSurfaceLinesContextTest.cs)	(revision 62d6426f4dc874b8e74a0c3ebe4c3491fa207af1)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PresentationObjects/RingtoetsPipingSurfaceLinesContextTest.cs	(.../RingtoetsPipingSurfaceLinesContextTest.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -25,6 +25,7 @@
 using NUnit.Framework;
 using Rhino.Mocks;
 using Ringtoets.Common.Data.AssessmentSection;
+using Ringtoets.Piping.Data;
 using Ringtoets.Piping.Forms.PresentationObjects;
 using Ringtoets.Piping.Primitives;
 
@@ -41,10 +42,12 @@
             var assessmentSectionMock = mocks.StrictMock<IAssessmentSection>();
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
+
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
 
             // Call
-            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSectionMock);
+            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSectionMock);
 
             // Assert
             Assert.IsInstanceOf<ObservableWrappedObjectContextBase<ObservableList<RingtoetsPipingSurfaceLine>>>(context);
@@ -58,13 +61,33 @@
         {
             // Setup
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
+            var failureMechanism = new PipingFailureMechanism();
 
             // Call
-            TestDelegate test = () => new RingtoetsPipingSurfaceLinesContext(surfaceLines, null);
+            TestDelegate test = () => new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, null);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(test);
             Assert.AreEqual("assessmentSection", exception.ParamName);
         }
+
+        [Test]
+        public void ParameteredConstructor_FailureMechanismNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            mocks.ReplayAll();
+
+            var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
+
+            // Call
+            TestDelegate call = () => new RingtoetsPipingSurfaceLinesContext(surfaceLines, null, assessmentSection);
+
+            // Assert
+            string paramName = Assert.Throws<ArgumentNullException>(call).ParamName;
+            Assert.AreEqual("failureMechanism", paramName);
+            mocks.VerifyAll();
+        }
     }
 }
\ No newline at end of file
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineCollectionTreeNodeInfoTest.cs
===================================================================
diff -u -r62d6426f4dc874b8e74a0c3ebe4c3491fa207af1 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineCollectionTreeNodeInfoTest.cs	(.../RingtoetsPipingSurfaceLineCollectionTreeNodeInfoTest.cs)	(revision 62d6426f4dc874b8e74a0c3ebe4c3491fa207af1)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineCollectionTreeNodeInfoTest.cs	(.../RingtoetsPipingSurfaceLineCollectionTreeNodeInfoTest.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -29,6 +29,7 @@
 using NUnit.Framework;
 using Rhino.Mocks;
 using Ringtoets.Common.Data.AssessmentSection;
+using Ringtoets.Piping.Data;
 using Ringtoets.Piping.Forms.PresentationObjects;
 using Ringtoets.Piping.Forms.Properties;
 using Ringtoets.Piping.Plugin;
@@ -88,8 +89,9 @@
             var assessmentSection = mocks.StrictMock<IAssessmentSection>();
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
-            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             var text = info.Text(ringtoetsPipingSurfaceLines);
@@ -105,8 +107,9 @@
             var assessmentSection = mocks.StrictMock<IAssessmentSection>();
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
-            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             var image = info.Image(ringtoetsPipingSurfaceLines);
@@ -122,8 +125,9 @@
             var assessmentSection = mocks.StrictMock<IAssessmentSection>();
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
-            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var ringtoetsPipingSurfaceLines = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             var foreColor = info.ForeColor(ringtoetsPipingSurfaceLines);
@@ -145,8 +149,10 @@
                 ringtoetsPipingSurfaceLine1, ringtoetsPipingSurfaceLine2
             };
 
-            var ringtoetsPipingSurfaceLineContext = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var failureMechanism = new PipingFailureMechanism();
 
+            var ringtoetsPipingSurfaceLineContext = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
+
             mocks.ReplayAll();
 
             // Call
@@ -169,8 +175,10 @@
                 ringtoetsPipingSurfaceLine1, ringtoetsPipingSurfaceLine2
             };
 
-            var ringtoetsPipingSurfaceLineContext = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var failureMechanism = new PipingFailureMechanism();
 
+            var ringtoetsPipingSurfaceLineContext = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
+
             mocks.ReplayAll();
 
             // Call
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineTreeNodeInfoTest.cs
===================================================================
diff -u -rdca4da4c1f78e4074d1a4513411e3509344ec169 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineTreeNodeInfoTest.cs	(.../RingtoetsPipingSurfaceLineTreeNodeInfoTest.cs)	(revision dca4da4c1f78e4074d1a4513411e3509344ec169)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/TreeNodeInfos/RingtoetsPipingSurfaceLineTreeNodeInfoTest.cs	(.../RingtoetsPipingSurfaceLineTreeNodeInfoTest.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -20,12 +20,18 @@
 // All rights reserved.
 
 using System.Linq;
+using Core.Common.Base;
+using Core.Common.Base.Geometry;
 using Core.Common.Controls.TreeView;
 using Core.Common.Gui;
 using Core.Common.Gui.ContextMenu;
 using Core.Common.TestUtil;
 using NUnit.Framework;
 using Rhino.Mocks;
+using Ringtoets.Common.Data.AssessmentSection;
+using Ringtoets.Common.Data.Calculation;
+using Ringtoets.Piping.Data;
+using Ringtoets.Piping.Forms.PresentationObjects;
 using Ringtoets.Piping.Forms.Properties;
 using Ringtoets.Piping.Plugin;
 using Ringtoets.Piping.Primitives;
@@ -67,8 +73,6 @@
             Assert.IsNull(info.ChildNodeObjects);
             Assert.IsNull(info.CanRename);
             Assert.IsNull(info.OnNodeRenamed);
-            Assert.IsNull(info.CanRemove);
-            Assert.IsNull(info.OnNodeRemoved);
             Assert.IsNull(info.CanCheck);
             Assert.IsNull(info.IsChecked);
             Assert.IsNull(info.OnNodeChecked);
@@ -111,12 +115,133 @@
         }
 
         [Test]
+        public void CanRemove_Always_ReturnTrue()
+        {
+            // Call
+            bool canRemove = info.CanRemove(null, null);
+
+            // Assert
+            Assert.IsTrue(canRemove);
+        }
+
+        [Test]
+        public void RemoveData_SurfaceLineFromCollection_SurfaceLineRemovedFromParentCollection()
+        {
+            // Setup
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            var observer = mocks.StrictMock<IObserver>();
+            observer.Expect(o => o.UpdateObserver());
+            mocks.ReplayAll();
+
+            var nodeData = new RingtoetsPipingSurfaceLine();
+            var failureMechanism = new PipingFailureMechanism();
+            failureMechanism.SurfaceLines.Add(nodeData);
+            failureMechanism.SurfaceLines.Add(new RingtoetsPipingSurfaceLine());
+            failureMechanism.SurfaceLines.Attach(observer);
+
+            var parentNodeData = new RingtoetsPipingSurfaceLinesContext(failureMechanism.SurfaceLines, failureMechanism, assessmentSection);
+
+            // Call
+            info.OnNodeRemoved(nodeData, parentNodeData);
+
+            // Assert
+            CollectionAssert.DoesNotContain(failureMechanism.SurfaceLines, nodeData);
+            // Expectancies checked in TearDown
+        }
+
+        [Test]
+        public void OnNodeRemoved_RemovedSurfaceLinePartOfCalculationInput_CalculationSurfaceLineCleared()
+        {
+            // Setup
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            var observer = mocks.StrictMock<IObserver>();
+            observer.Expect(o => o.UpdateObserver());
+            var calculation1Observer = mocks.StrictMock<IObserver>();
+            calculation1Observer.Expect(o => o.UpdateObserver());
+            var calculation2Observer = mocks.StrictMock<IObserver>();
+            calculation2Observer.Expect(o => o.UpdateObserver());
+            var calculation3Observer = mocks.StrictMock<IObserver>();
+            calculation3Observer.Expect(o => o.UpdateObserver()).Repeat.Never();
+            mocks.ReplayAll();
+
+            var nodeData = new RingtoetsPipingSurfaceLine();
+            nodeData.SetGeometry(new[]
+            {
+                new Point3D(1, 2, 3),
+                new Point3D(4, 5, 6)
+            });
+            var failureMechanism = new PipingFailureMechanism();
+            failureMechanism.SurfaceLines.Add(nodeData);
+            var otherSurfaceline = new RingtoetsPipingSurfaceLine();
+            otherSurfaceline.SetGeometry(new[]
+            {
+                new Point3D(7, 8, 9),
+                new Point3D(0, 1, 2)
+            });
+            failureMechanism.SurfaceLines.Add(otherSurfaceline);
+            failureMechanism.SurfaceLines.Attach(observer);
+
+            var generalInputs = new GeneralPipingInput();
+            var calculation1 = new PipingCalculationScenario(generalInputs)
+            {
+                InputParameters =
+                {
+                    SurfaceLine = nodeData
+                }
+            };
+            calculation1.InputParameters.Attach(calculation1Observer);
+            var calculation2 = new PipingCalculationScenario(generalInputs)
+            {
+                InputParameters =
+                {
+                    SurfaceLine = nodeData
+                }
+            };
+            calculation2.InputParameters.Attach(calculation2Observer);
+            var calculation3 = new PipingCalculationScenario(generalInputs)
+            {
+                InputParameters =
+                {
+                    SurfaceLine = otherSurfaceline
+                }
+            };
+            calculation3.InputParameters.Attach(calculation3Observer);
+
+            var groupWithCalculation = new CalculationGroup("A", true)
+            {
+                Children =
+                {
+                    calculation2
+                }
+            };
+
+            failureMechanism.CalculationsGroup.Children.Add(calculation1);
+            failureMechanism.CalculationsGroup.Children.Add(groupWithCalculation);
+            failureMechanism.CalculationsGroup.Children.Add(calculation3);
+
+            var parentNodeData = new RingtoetsPipingSurfaceLinesContext(failureMechanism.SurfaceLines, failureMechanism, assessmentSection);
+
+            // Call
+            info.OnNodeRemoved(nodeData, parentNodeData);
+
+            // Assert
+            CollectionAssert.DoesNotContain(failureMechanism.SurfaceLines, nodeData);
+
+            Assert.IsNull(calculation1.InputParameters.SurfaceLine);
+            Assert.IsNull(calculation2.InputParameters.SurfaceLine);
+            Assert.IsNotNull(calculation3.InputParameters.SurfaceLine,
+                             "Calculation with different surfaceline should not be affected.");
+            // Expectancies checked in TearDown
+        }
+
+        [Test]
         public void ContextMenuStrip_Always_CallsBuilder()
         {
             // Setup
             var menuBuilderMock = mocks.StrictMock<IContextMenuBuilder>();
 
             menuBuilderMock.Expect(mb => mb.AddPropertiesItem()).Return(menuBuilderMock);
+            menuBuilderMock.Expect(mb => mb.AddDeleteItem()).Return(menuBuilderMock);
             menuBuilderMock.Expect(mb => mb.Build()).Return(null);
 
             using (var treeViewControl = new TreeViewControl())
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/Views/PipingFailureMechanismViewTest.cs
===================================================================
diff -u -r11f0867b39150ae5fac83dc178a89fee46d27611 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/Views/PipingFailureMechanismViewTest.cs	(.../PipingFailureMechanismViewTest.cs)	(revision 11f0867b39150ae5fac83dc178a89fee46d27611)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/Views/PipingFailureMechanismViewTest.cs	(.../PipingFailureMechanismViewTest.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -332,25 +332,15 @@
                     new Point3D(4, 5, 6)
                 };
 
-                var geometry2 = new Collection<Point3D>
-                {
-                    new Point3D(11, 22, 33),
-                    new Point3D(44, 55, 66)
-                };
-
                 surfaceLine.SetGeometry(geometry1);
-                pipingFailureMechanism.SurfaceLines.Add(surfaceLine);
 
                 view.Data = pipingContext;
 
                 var surfaceLineMapData = (MapLineData) map.Data.Collection.ElementAt(surfaceLinesIndex);
 
-                // Precondition
-                AssertSurfacelinesMapData(pipingFailureMechanism.SurfaceLines, surfaceLineMapData);
-
                 // Call
-                surfaceLine.SetGeometry(geometry2);
-                pipingFailureMechanism.NotifyObservers();
+                pipingFailureMechanism.SurfaceLines.Add(surfaceLine);
+                pipingFailureMechanism.SurfaceLines.NotifyObservers();
 
                 // Assert
                 AssertSurfacelinesMapData(pipingFailureMechanism.SurfaceLines, surfaceLineMapData);
Index: Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/ImportInfos/RingtoetsPipingSurfaceLinesContextImportInfoTest.cs
===================================================================
diff -u -r62d6426f4dc874b8e74a0c3ebe4c3491fa207af1 -r7641c0e215cd2e90a9b1828778906cfee05ff592
--- Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/ImportInfos/RingtoetsPipingSurfaceLinesContextImportInfoTest.cs	(.../RingtoetsPipingSurfaceLinesContextImportInfoTest.cs)	(revision 62d6426f4dc874b8e74a0c3ebe4c3491fa207af1)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/ImportInfos/RingtoetsPipingSurfaceLinesContextImportInfoTest.cs	(.../RingtoetsPipingSurfaceLinesContextImportInfoTest.cs)	(revision 7641c0e215cd2e90a9b1828778906cfee05ff592)
@@ -30,6 +30,7 @@
 using NUnit.Framework;
 using Rhino.Mocks;
 using Ringtoets.Common.Data.AssessmentSection;
+using Ringtoets.Piping.Data;
 using Ringtoets.Piping.Forms.PresentationObjects;
 using Ringtoets.Piping.Primitives;
 using PipingFormsResources = Ringtoets.Piping.Forms.Properties.Resources;
@@ -94,9 +95,10 @@
             assessmentSection.ReferenceLine = null;
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
 
-            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             bool isEnabled = importInfo.IsEnabled(context);
@@ -115,9 +117,10 @@
             assessmentSection.ReferenceLine = new ReferenceLine();
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
 
-            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var context = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             bool isEnabled = importInfo.IsEnabled(context);
@@ -158,9 +161,10 @@
             assessmentSection.ReferenceLine = referenceLine;
             mocks.ReplayAll();
 
+            var failureMechanism = new PipingFailureMechanism();
             var surfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
 
-            var importTarget = new RingtoetsPipingSurfaceLinesContext(surfaceLines, assessmentSection);
+            var importTarget = new RingtoetsPipingSurfaceLinesContext(surfaceLines, failureMechanism, assessmentSection);
 
             // Call
             IFileImporter importer = importInfo.CreateFileImporter(importTarget, filePath);