Index: DamEngine/trunk/src/Deltares.DamEngine.Data/General/SoilGeometryProbability.cs
===================================================================
diff -u -r2173 -r3041
--- DamEngine/trunk/src/Deltares.DamEngine.Data/General/SoilGeometryProbability.cs	(.../SoilGeometryProbability.cs)	(revision 2173)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/General/SoilGeometryProbability.cs	(.../SoilGeometryProbability.cs)	(revision 3041)
@@ -19,6 +19,7 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using Deltares.DamEngine.Data.Geotechnics;
 
 namespace Deltares.DamEngine.Data.General
@@ -120,6 +121,27 @@
                 return StiFileName;
             }
         }
-    }
 
+        /// <summary>Determines the soilProfile1D at x coordinate, regardless of the soil profile type (1D or 2D).
+        /// Does not support *.sti files</summary>
+        /// <param name="xCoordinate">The x coordinate.</param>
+        /// <returns></returns>
+        /// <exception cref="NotSupportedException"></exception>
+        public SoilProfile1D DetermineSoilProfile1DAtX(double xCoordinate)
+        {
+            SoilProfile1D soilProfile1D;
+            switch (this.SoilProfileType)
+            {
+                case SoilProfileType.ProfileType1D:
+                    soilProfile1D = SoilProfile1D;
+                    break;
+                case SoilProfileType.ProfileType2D:
+                    soilProfile1D = SoilProfile2D.GetSoilProfile1D(xCoordinate);
+                    break;
+                default:
+                    throw new NotSupportedException(String.Format("{0} not supported", SoilProfileType));
+            }
+            return soilProfile1D;
+        }
+    }
 }
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs
===================================================================
diff -u -r3040 -r3041
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs	(.../UpliftVanGridCreator.cs)	(revision 3040)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs	(.../UpliftVanGridCreator.cs)	(revision 3041)
@@ -20,6 +20,7 @@
 // All rights reserved.
 
 using System;
+using System.Linq;
 using Deltares.DamEngine.Calculators.KernelWrappers.MacroStabilityCommon;
 using Deltares.DamEngine.Data.General;
 using Deltares.DamEngine.Data.Geotechnics;
@@ -94,14 +95,14 @@
         /// <summary>Determines the tangent lines.</summary>
         /// <param name="upliftVanCalculationGrid">The uplift van calculation grid.</param>
         /// <param name="slipCircleDefinition">The slip circle definition.</param>
-        /// <param name="bottomAquiferLevel">The top bottom aquifer at middle of left grid.</param>
-        /// <param name="surfaceLevel"></param>
+        /// <param name="soilProfile1D">The soil profile1 d.</param>
         /// <param name="minimumCircleDepth">The minimum circle depth.</param>
-        public static void DetermineTangentLines(UpliftVanCalculationGrid upliftVanCalculationGrid, 
-            SlipCircleDefinition slipCircleDefinition, double bottomAquiferLevel, 
-            double surfaceLevel, double minimumCircleDepth)
+        public static void DetermineTangentLines(UpliftVanCalculationGrid upliftVanCalculationGrid, SlipCircleDefinition slipCircleDefinition, 
+            SoilProfile1D soilProfile1D, double minimumCircleDepth)
         {
-            double bottomTangentLines = bottomAquiferLevel - slipCircleDefinition.UpliftVanTangentLinesDistance;
+            double topOfBottomLayer = soilProfile1D.Layers.Last().TopLevel;
+            double surfaceLevel = soilProfile1D.Layers.First().TopLevel;
+            double bottomTangentLines = topOfBottomLayer - slipCircleDefinition.UpliftVanTangentLinesDistance;
             bottomTangentLines = Math.Min(bottomTangentLines, surfaceLevel - minimumCircleDepth);
             double topTangentLines = bottomTangentLines;
             int tangentLinesCount = 1;
@@ -114,7 +115,6 @@
             upliftVanCalculationGrid.TangentLineCount = tangentLinesCount;
             upliftVanCalculationGrid.TangentLineZTop = topTangentLines;
             upliftVanCalculationGrid.TangentLineZBottom = bottomTangentLines;
-
         }
     }
 }
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapper.cs
===================================================================
diff -u -r3040 -r3041
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapper.cs	(.../MacroStabilityInwardsKernelWrapper.cs)	(revision 3040)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapper.cs	(.../MacroStabilityInwardsKernelWrapper.cs)	(revision 3041)
@@ -45,6 +45,7 @@
 using LogMessage = Deltares.DamEngine.Data.Standard.Logging.LogMessage;
 using LogMessageType = Deltares.DamEngine.Data.Standard.Logging.LogMessageType;
 using Soil = Deltares.DamEngine.Data.Geotechnics.Soil;
+using SoilProfile = Deltares.DamEngine.Data.Geotechnics.SoilProfile;
 using UpliftVanCalculationGrid = Deltares.DamEngine.Calculators.KernelWrappers.MacroStabilityCommon.UpliftVanCalculationGrid;
 
 namespace Deltares.DamEngine.Calculators.KernelWrappers.MacroStabilityInwards
@@ -99,6 +100,8 @@
                         var penetrationLength = damKernelInput.Location.ModelParametersForPlLines.PenetrationLength;
                         var waterNet = PlLinesToWaternetConverter.ConvertPlLineToWaternet(plLines, damKernelInput.SubSoilScenario.SoilProfile1D,
                             penetrationLength, left, right);
+
+                        // Define traffic load
                         TrafficLoad trafficLoad = null;
                         if (damKernelInput.Location.StabilityOptions != null && damKernelInput.Location.StabilityOptions.TrafficLoad.HasValue &&
                             !damKernelInput.Location.StabilityOptions.TrafficLoad.Value.AlmostZero())
@@ -111,6 +114,7 @@
                                 .CharacteristicPoints.GetGeometryPoint(CharacteristicPointType.TrafficLoadOutside).X;
                         }
 
+                        // Define slip circle UpliftVan
                         var slipCircleDefinition = damKernelInput.DamFailureMechanismeCalculationSpecification
                             .FailureMechanismParametersMStab.MStabParameters.SlipCircleDefinition;
                         double minimumCircleDepth = damKernelInput.DamFailureMechanismeCalculationSpecification
@@ -119,10 +123,11 @@
                             slipCircleDefinition, damKernelInput.Location.SurfaceLine);
                         double centerOfLeftGridXCoordinate =
                             (upliftVanCalculationGrid.LeftGridXLeft + upliftVanCalculationGrid.LeftGridXRight) * 0.5;
-                        double levelBottomAquiferAtMiddleOfLeftGrid = DetermineLevelBottomLayerAtX(damKernelInput.SubSoilScenario, centerOfLeftGridXCoordinate);
-                        double surfaceLevelAtMiddleOfLeftGrid = damKernelInput.Location.SurfaceLine.Geometry.GetZatX(centerOfLeftGridXCoordinate);
-                        UpliftVanGridCreator.DetermineTangentLines(upliftVanCalculationGrid, slipCircleDefinition,
-                            levelBottomAquiferAtMiddleOfLeftGrid, surfaceLevelAtMiddleOfLeftGrid, minimumCircleDepth);
+                        SoilProfile1D soilProfile1DAtCenterOfLeftGridXCoordinate =
+                            damKernelInput.SubSoilScenario.DetermineSoilProfile1DAtX(centerOfLeftGridXCoordinate);
+                        UpliftVanGridCreator.DetermineTangentLines(upliftVanCalculationGrid, slipCircleDefinition, 
+                            soilProfile1DAtCenterOfLeftGridXCoordinate, minimumCircleDepth);
+
                         FillMacroStabilityWrapperInputFromEngine fillMacroStabilityWrapperFromEngine = new FillMacroStabilityWrapperInputFromEngine()
                         {
                             TrafficLoad = trafficLoad,
@@ -146,24 +151,6 @@
             return PrepareResult.NotRelevant;
         }
 
-        private double DetermineLevelBottomLayerAtX(SoilGeometryProbability subSoilScenario, double xCoordinate)
-        {
-            SoilProfile1D soilProfile1D;
-            switch (subSoilScenario.SoilProfileType)
-            {
-                case SoilProfileType.ProfileType1D:
-                    soilProfile1D = subSoilScenario.SoilProfile1D;
-                    break;
-                case SoilProfileType.ProfileType2D:
-                    soilProfile1D = subSoilScenario.SoilProfile2D.GetSoilProfile1D(xCoordinate);
-                    break;
-                default:
-                    throw new NotSupportedException(String.Format("{0} not supported", subSoilScenario.SoilProfileType));
-            }
-
-            return soilProfile1D.Layers.Last().TopLevel;
-        }
-
         private void EnsureSoilProfile2DIsFilled(SoilGeometryProbability subSoilScenario, SurfaceLine2 surfaceLine2, Soil dikeEmbankmentSoil)
         {
             var soilProfile2D = subSoilScenario.SoilProfile2D;