Index: src/Plugins/Wti/Wti.Forms/NodePresenters/PipingDataNodePresenter.cs
===================================================================
diff -u -r325410362b50750d3c291d19c1526799c9b1c583 -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Forms/NodePresenters/PipingDataNodePresenter.cs	(.../PipingDataNodePresenter.cs)	(revision 325410362b50750d3c291d19c1526799c9b1c583)
+++ src/Plugins/Wti/Wti.Forms/NodePresenters/PipingDataNodePresenter.cs	(.../PipingDataNodePresenter.cs)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -4,6 +4,8 @@
 using DelftTools.Controls;
 using DelftTools.Controls.Swf;
 using DelftTools.Utils.Collections;
+using log4net;
+using Wti.Calculation.Piping;
 using Wti.Data;
 using Wti.Forms.Properties;
 using Wti.Service;
@@ -86,7 +88,14 @@
 
         private void PerformPipingCalculation(PipingData pipingData)
         {
-            PipingCalculationService.Calculate(pipingData);
+            try
+            {
+                PipingCalculationService.Calculate(pipingData);
+            }
+            catch (PipingCalculationException e)
+            {
+                LogManager.GetLogger(typeof(PipingCalculationService)).Error(String.Format(Resources.ErrorInPipingCalculation_0, e.Message));
+            }
             pipingData.NotifyObservers();
         }
 
Index: src/Plugins/Wti/Wti.Forms/Properties/Resources.Designer.cs
===================================================================
diff -u -rd6424435444e760d052fe6d8c8786e01bddf9d2b -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision d6424435444e760d052fe6d8c8786e01bddf9d2b)
+++ src/Plugins/Wti/Wti.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -1,7 +1,7 @@
 //------------------------------------------------------------------------------
 // <auto-generated>
 //     This code was generated by a tool.
-//     Runtime Version:4.0.30319.18444
+//     Runtime Version:4.0.30319.34209
 //
 //     Changes to this file may cause incorrect behavior and will be lost if
 //     the code is regenerated.
@@ -79,6 +79,15 @@
         }
         
         /// <summary>
+        ///   Looks up a localized string similar to Piping berekening niet gelukt: {0}.
+        /// </summary>
+        public static string ErrorInPipingCalculation_0 {
+            get {
+                return ResourceManager.GetString("ErrorInPipingCalculation_0", resourceCulture);
+            }
+        }
+        
+        /// <summary>
         ///   Looks up a localized resource of type System.Drawing.Bitmap.
         /// </summary>
         public static System.Drawing.Bitmap FolderIcon {
Index: src/Plugins/Wti/Wti.Forms/Properties/Resources.resx
===================================================================
diff -u -rd6424435444e760d052fe6d8c8786e01bddf9d2b -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision d6424435444e760d052fe6d8c8786e01bddf9d2b)
+++ src/Plugins/Wti/Wti.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -334,4 +334,7 @@
   <data name="AddPipingFailureMechanismContextMenuItem" xml:space="preserve">
     <value>Voeg piping faalmechanisme toe</value>
   </data>
+  <data name="ErrorInPipingCalculation_0" xml:space="preserve">
+    <value>Piping berekening niet gelukt: {0}</value>
+  </data>
 </root>
\ No newline at end of file
Index: src/Plugins/Wti/Wti.Forms/Wti.Forms.csproj
===================================================================
diff -u -r6dbce7d02bbc8849c767bf7963df7127a98c2897 -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Forms/Wti.Forms.csproj	(.../Wti.Forms.csproj)	(revision 6dbce7d02bbc8849c767bf7963df7127a98c2897)
+++ src/Plugins/Wti/Wti.Forms/Wti.Forms.csproj	(.../Wti.Forms.csproj)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -35,6 +35,10 @@
     <DocumentationFile>bin\Release\Wti.Forms.XML</DocumentationFile>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\..\..\..\lib\log4net.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
     <Reference Include="System.Drawing" />
@@ -87,6 +91,7 @@
     <ProjectReference Include="..\..\..\Common\Wti.Base\Wti.Base.csproj">
       <Project>{c90b77da-e421-43cc-b82e-529651bc21ac}</Project>
       <Name>Wti.Base</Name>
+      <Private>True</Private>
     </ProjectReference>
     <ProjectReference Include="..\Wti.Calculation\Wti.Calculation.csproj">
       <Project>{D64E4F0E-E341-496F-82B2-941AD202B4E3}</Project>
Index: src/Plugins/Wti/Wti.Service/PipingCalculationService.cs
===================================================================
diff -u -ra0b4632c9d4f89335cbb7e0de45e525481586392 -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Service/PipingCalculationService.cs	(.../PipingCalculationService.cs)	(revision a0b4632c9d4f89335cbb7e0de45e525481586392)
+++ src/Plugins/Wti/Wti.Service/PipingCalculationService.cs	(.../PipingCalculationService.cs)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -1,8 +1,6 @@
-using System;
-using log4net;
+using System.Collections.Generic;
 using Wti.Calculation.Piping;
 using Wti.Data;
-using Wti.Service.Properties;
 
 namespace Wti.Service
 {
@@ -12,52 +10,49 @@
     /// </summary>
     public static class PipingCalculationService
     {
-        private static readonly ILog Logger = LogManager.GetLogger(typeof(PipingCalculationService));
-
         /// <summary>
         /// Performs a piping calculation based on the supplied <see cref="PipingData"/> and sets <see cref="PipingData.Output"/>
         /// to the <see cref="PipingCalculationResult"/> if the calculation was successful.
         /// </summary>
         /// <param name="pipingData">The <see cref="PipingData"/> to base the input for the calculation upon.</param>
+        /// <exception cref="PipingCalculationException">Thrown when calling <see cref="Validate"/> would return a non empty <see cref="List{T}"/>.</exception>
         public static void Calculate(PipingData pipingData)
         {
-            try
-            {
-                var input = new PipingCalculationInput(
-                    pipingData.WaterVolumetricWeight,
-                    pipingData.UpliftModelFactor,
-                    pipingData.AssessmentLevel,
-                    pipingData.PiezometricHeadExit,
-                    pipingData.DampingFactorExit,
-                    pipingData.PhreaticLevelExit,
-                    pipingData.PiezometricHeadPolder,
-                    pipingData.CriticalHeaveGradient,
-                    pipingData.ThicknessCoverageLayer,
-                    pipingData.SellmeijerModelFactor,
-                    pipingData.SellmeijerReductionFactor,
-                    pipingData.SeepageLength,
-                    pipingData.SandParticlesVolumicWeight,
-                    pipingData.WhitesDragCoefficient,
-                    pipingData.Diameter70,
-                    pipingData.DarcyPermeability,
-                    pipingData.WaterKinematicViscosity,
-                    pipingData.Gravity,
-                    pipingData.ThicknessAquiferLayer,
-                    pipingData.MeanDiameter70,
-                    pipingData.BeddingAngle,
-                    pipingData.ExitPointXCoordinate
-                    );
-                var pipingCalculation = new PipingCalculation(input);
-                var pipingResult = pipingCalculation.Calculate();
+            var input = new PipingCalculationInput(
+                pipingData.WaterVolumetricWeight,
+                pipingData.UpliftModelFactor,
+                pipingData.AssessmentLevel,
+                pipingData.PiezometricHeadExit,
+                pipingData.DampingFactorExit,
+                pipingData.PhreaticLevelExit,
+                pipingData.PiezometricHeadPolder,
+                pipingData.CriticalHeaveGradient,
+                pipingData.ThicknessCoverageLayer,
+                pipingData.SellmeijerModelFactor,
+                pipingData.SellmeijerReductionFactor,
+                pipingData.SeepageLength,
+                pipingData.SandParticlesVolumicWeight,
+                pipingData.WhitesDragCoefficient,
+                pipingData.Diameter70,
+                pipingData.DarcyPermeability,
+                pipingData.WaterKinematicViscosity,
+                pipingData.Gravity,
+                pipingData.ThicknessAquiferLayer,
+                pipingData.MeanDiameter70,
+                pipingData.BeddingAngle,
+                pipingData.ExitPointXCoordinate
+                );
+            var pipingCalculation = new PipingCalculation(input);
+            var pipingResult = pipingCalculation.Calculate();
 
-                pipingData.Output = new PipingOutput(pipingResult.UpliftZValue,
-                                                     pipingResult.UpliftFactorOfSafety,
-                                                     pipingResult.HeaveZValue, pipingResult.HeaveFactorOfSafety, pipingResult.SellmeijerZValue, pipingResult.SellmeijerFactorOfSafety);
-            }
-            catch (PipingCalculationException e)
-            {
-                Logger.Error(String.Format(Resources.ErrorInPipingCalculation_0, e.Message));
-            }
+            pipingData.Output = new PipingOutput(pipingResult.UpliftZValue,
+                                                    pipingResult.UpliftFactorOfSafety,
+                                                    pipingResult.HeaveZValue, pipingResult.HeaveFactorOfSafety, pipingResult.SellmeijerZValue, pipingResult.SellmeijerFactorOfSafety);
         }
+
+        public static List<string> Validate(PipingData pipingData)
+        {
+            return null;
+        } 
     }
 }
\ No newline at end of file
Fisheye: Tag 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9 refers to a dead (removed) revision in file `src/Plugins/Wti/Wti.Service/Properties/Resources.Designer.cs'.
Fisheye: No comparison available.  Pass `N' to diff?
Fisheye: Tag 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9 refers to a dead (removed) revision in file `src/Plugins/Wti/Wti.Service/Properties/Resources.resx'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: src/Plugins/Wti/Wti.Service/Wti.Service.csproj
===================================================================
diff -u -r6dbce7d02bbc8849c767bf7963df7127a98c2897 -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- src/Plugins/Wti/Wti.Service/Wti.Service.csproj	(.../Wti.Service.csproj)	(revision 6dbce7d02bbc8849c767bf7963df7127a98c2897)
+++ src/Plugins/Wti/Wti.Service/Wti.Service.csproj	(.../Wti.Service.csproj)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -55,11 +55,6 @@
     </Compile>
     <Compile Include="PipingCalculationService.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Properties\Resources.Designer.cs">
-      <AutoGen>True</AutoGen>
-      <DesignTime>True</DesignTime>
-      <DependentUpon>Resources.resx</DependentUpon>
-    </Compile>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\..\Common\DelftTools.Controls.Swf\DelftTools.Controls.Swf.csproj">
@@ -87,12 +82,6 @@
       <Name>Wti.Data</Name>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup>
-    <EmbeddedResource Include="Properties\Resources.resx">
-      <Generator>ResXFileCodeGenerator</Generator>
-      <LastGenOutput>Resources.Designer.cs</LastGenOutput>
-    </EmbeddedResource>
-  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
     <PreBuildEvent>
Index: test/Plugins/Wti/Wti.Calculation.Test/Piping/PipingCalculationTest.cs
===================================================================
diff -u -r56799a04d6d49cdcb6706d8ada0f1d1e5d7d08dc -r82e08784e174b6b2799fc19cc04e7d7aeb7b84e9
--- test/Plugins/Wti/Wti.Calculation.Test/Piping/PipingCalculationTest.cs	(.../PipingCalculationTest.cs)	(revision 56799a04d6d49cdcb6706d8ada0f1d1e5d7d08dc)
+++ test/Plugins/Wti/Wti.Calculation.Test/Piping/PipingCalculationTest.cs	(.../PipingCalculationTest.cs)	(revision 82e08784e174b6b2799fc19cc04e7d7aeb7b84e9)
@@ -112,6 +112,131 @@
             Assert.IsTrue(validationMessages.Any(message => message.Contains("phiExit - hExit")));
         }
 
+        [Test]
+        public void Validate_PhreaticLevelExitZero_TwoValidationMessageForRExit()
+        {
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                DampingFactorExit = 0
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(2, validationMessages.Count);
+            Assert.AreEqual(2, validationMessages.Count(message => message.Contains("Rexit")));
+        }
+
+        [Test]
+        public void Validate_ThicknessCoverageLayerZero_ValidationMessageForDTotal()
+        {
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                ThicknessCoverageLayer = 0
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(1, validationMessages.Count);
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("Dtotal")));
+        }
+
+        [Test]
+        public void Validate_ThicknessAquiferLayerZero_ValidationMessageForDAquifer()
+        {
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                ThicknessAquiferLayer = 0
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(1, validationMessages.Count);
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("DAquifer")));
+        }
+
+        [Test]
+        public void Validate_VolumetricWeightWaterZero_ValidationMessageForVolumetricWeightWater()
+        {                                                                                                                                                                                
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                WaterVolumetricWeight = 0
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(1, validationMessages.Count);
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("Volumetric weight water")));
+        }
+
+        [Test]
+        [TestCase(2, 1, 2, 0.5)]
+        [TestCase(1, 1, 0, 2)]
+        [TestCase(8, 4, 2, 2)]
+        public void Validate_DifferenceAssessmentLevelAndPhreaticLevelExitEqualToSellmeijerReductionFactorTimesThicknessCoverageLayer_ValidationMessageForHRiverHExitRcDTotal(
+            double assessmentLevel, double phreaticLevelExit, double sellmeijerReductionFactor, double thicknessCoverageLayer)
+        {
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                AssessmentLevel = assessmentLevel,
+                PhreaticLevelExit = phreaticLevelExit,
+                SellmeijerReductionFactor = sellmeijerReductionFactor,
+                ThicknessCoverageLayer = thicknessCoverageLayer
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(1, validationMessages.Count);
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("HRiver - HExit - (Rc*DTotal)")));
+        }
+
+        [Test]
+        public void Validate_AssessmentLevelPhreaticLevelExitSellmeijerReductionFactorThicknessCoverageLayerZero_ValidationMessageForHRiverHExitRcDTotalAndDTotal()
+        {
+            // Setup
+            PipingCalculationInput input = new TestPipingInput
+            {
+                AssessmentLevel = 0,
+                PhreaticLevelExit = 0,
+                SellmeijerReductionFactor = 0,
+                ThicknessCoverageLayer = 0
+            }.AsRealInput();
+
+            var calculation = new PipingCalculation(input);
+
+            // Call
+            List<string> validationMessages = calculation.Validate();
+
+            // Assert
+            Assert.AreEqual(2, validationMessages.Count);
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("HRiver - HExit - (Rc*DTotal)")));
+            Assert.IsTrue(validationMessages.Any(message => message.Contains("Dtotal")));
+        }
+
         class TestPipingInput
         {
             public double WaterVolumetricWeight;
@@ -142,35 +267,35 @@
 
             public TestPipingInput()
             {
-                WaterVolumetricWeight = NextDouble();
-                UpliftModelFactor = NextDouble();
-                AssessmentLevel = NextDouble();
-                PiezometricHeadExit = NextDouble();
-                PhreaticLevelExit = NextDouble();
-                DampingFactorExit = NextDouble();
-                PiezometricHeadPolder = NextDouble();
-                CriticalHeaveGradient = NextDouble();
-                ThicknessCoverageLayer = NextDouble();
-                SellmeijerModelFactor = NextDouble();
-                SellmeijerReductionFactor = NextDouble();
-                SeepageLength = NextDouble();
-                SandParticlesVolumicWeight = NextDouble();
-                WhitesDragCoefficient = NextDouble();
-                Diameter70 = NextDouble();
-                DarcyPermeability = NextDouble();
-                WaterKinematicViscosity = NextDouble();
-                Gravity = NextDouble();
-                ExitPointXCoordinate = NextDouble();
-                BeddingAngle = NextDouble();
-                MeanDiameter70 = NextDouble();
-                ThicknessAquiferLayer = NextDouble();
+                WaterVolumetricWeight = NextIncrementalDouble();
+                UpliftModelFactor = NextIncrementalDouble();
+                AssessmentLevel = NextIncrementalDouble();
+                PiezometricHeadExit = NextIncrementalDouble();
+                PhreaticLevelExit = NextIncrementalDouble();
+                DampingFactorExit = NextIncrementalDouble();
+                PiezometricHeadPolder = NextIncrementalDouble();
+                CriticalHeaveGradient = NextIncrementalDouble();
+                ThicknessCoverageLayer = NextIncrementalDouble();
+                SellmeijerModelFactor = NextIncrementalDouble();
+                SellmeijerReductionFactor = NextIncrementalDouble();
+                SeepageLength = NextIncrementalDouble();
+                SandParticlesVolumicWeight = NextIncrementalDouble();
+                WhitesDragCoefficient = NextIncrementalDouble();
+                Diameter70 = NextIncrementalDouble();
+                DarcyPermeability = NextIncrementalDouble();
+                WaterKinematicViscosity = NextIncrementalDouble();
+                Gravity = NextIncrementalDouble();
+                ExitPointXCoordinate = NextIncrementalDouble();
+                BeddingAngle = NextIncrementalDouble();
+                MeanDiameter70 = NextIncrementalDouble();
+                ThicknessAquiferLayer = NextIncrementalDouble();
             }
 
             /// <summary>
             /// The returned double is sure to be different from the last time it was called.
             /// </summary>
             /// <returns></returns>
-            private double NextDouble()
+            private double NextIncrementalDouble()
             {
                 return last += random.NextDouble() + 1e-6;
             }