Index: Ringtoets/Piping/test/Ringtoets.Piping.Service.Test/PipingCalculationServiceTest.cs
===================================================================
diff -u -r686466dda6406ee2c7fb1f33faa60494878b1fc8 -r4ed2f23175341a2f0a836874dce514cd88e96e8d
--- Ringtoets/Piping/test/Ringtoets.Piping.Service.Test/PipingCalculationServiceTest.cs	(.../PipingCalculationServiceTest.cs)	(revision 686466dda6406ee2c7fb1f33faa60494878b1fc8)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Service.Test/PipingCalculationServiceTest.cs	(.../PipingCalculationServiceTest.cs)	(revision 4ed2f23175341a2f0a836874dce514cd88e96e8d)
@@ -1046,17 +1046,19 @@
             UpliftCalculatorStub upliftCalculator = testFactory.LastCreatedUpliftCalculator;
             SellmeijerCalculatorStub sellmeijerCalculator = testFactory.LastCreatedSellmeijerCalculator;
 
+            var derivedPipingInput = new DerivedPipingInput(input);
+
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetThicknessCoverageLayer(input).GetDesignValue(),
                             heaveCalculator.DTotal,
-                            input.ThicknessCoverageLayer.GetAccuracy());
+                            derivedPipingInput.ThicknessCoverageLayer.GetAccuracy());
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetPhreaticLevelExit(input).GetDesignValue(),
                             heaveCalculator.HExit,
                             input.PhreaticLevelExit.GetAccuracy());
             Assert.AreEqual(input.CriticalHeaveGradient, heaveCalculator.Ich);
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetPhreaticLevelExit(input).GetDesignValue(),
                             heaveCalculator.PhiPolder,
                             input.PhreaticLevelExit.GetAccuracy());
-            Assert.AreEqual(input.PiezometricHeadExit.Value, heaveCalculator.PhiExit);
+            Assert.AreEqual(derivedPipingInput.PiezometricHeadExit.Value, heaveCalculator.PhiExit);
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetDampingFactorExit(input).GetDesignValue(),
                             heaveCalculator.RExit,
                             input.DampingFactorExit.GetAccuracy());
@@ -1066,7 +1068,7 @@
                             input.PhreaticLevelExit.GetAccuracy());
             Assert.AreEqual(input.AssessmentLevel.Value, upliftCalculator.HRiver);
             Assert.AreEqual(input.UpliftModelFactor, upliftCalculator.ModelFactorUplift);
-            Assert.AreEqual(input.PiezometricHeadExit.Value, upliftCalculator.PhiExit);
+            Assert.AreEqual(derivedPipingInput.PiezometricHeadExit.Value, upliftCalculator.PhiExit);
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetPhreaticLevelExit(input).GetDesignValue(),
                             upliftCalculator.PhiPolder,
                             input.PhreaticLevelExit.GetAccuracy());
@@ -1083,7 +1085,7 @@
 
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetSeepageLength(input).GetDesignValue(),
                             sellmeijerCalculator.SeepageLength,
-                            input.SeepageLength.GetAccuracy());
+                            derivedPipingInput.SeepageLength.GetAccuracy());
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetPhreaticLevelExit(input).GetDesignValue(),
                             sellmeijerCalculator.HExit,
                             input.PhreaticLevelExit.GetAccuracy());
@@ -1096,17 +1098,17 @@
             Assert.AreEqual(input.BeddingAngle, sellmeijerCalculator.BeddingAngle);
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetThicknessCoverageLayer(input).GetDesignValue(),
                             sellmeijerCalculator.DTotal,
-                            input.ThicknessCoverageLayer.GetAccuracy());
+                            derivedPipingInput.ThicknessCoverageLayer.GetAccuracy());
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetDiameter70(input).GetDesignValue(),
                             sellmeijerCalculator.D70,
-                            input.Diameter70.GetAccuracy());
+                            derivedPipingInput.DiameterD70.GetAccuracy());
             Assert.AreEqual(input.MeanDiameter70, sellmeijerCalculator.D70Mean);
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetThicknessAquiferLayer(input).GetDesignValue(),
                             sellmeijerCalculator.DAquifer,
-                            input.ThicknessAquiferLayer.GetAccuracy());
+                            derivedPipingInput.ThicknessAquiferLayer.GetAccuracy());
             Assert.AreEqual(PipingSemiProbabilisticDesignVariableFactory.GetDarcyPermeability(input).GetDesignValue(),
                             sellmeijerCalculator.DarcyPermeability,
-                            input.DarcyPermeability.GetAccuracy());
+                            derivedPipingInput.DarcyPermeability.GetAccuracy());
             Assert.AreEqual(input.SandParticlesVolumicWeight, sellmeijerCalculator.GammaSubParticles);
             Assert.AreEqual(input.Gravity, sellmeijerCalculator.Gravity);
         }