Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/XMLSoilProfile2DConverter.cs
===================================================================
diff -u -r3034 -r3043
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/XMLSoilProfile2DConverter.cs	(.../XMLSoilProfile2DConverter.cs)	(revision 3034)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/DamEngineIo/XMLSoilProfile2DConverter.cs	(.../XMLSoilProfile2DConverter.cs)	(revision 3043)
@@ -25,6 +25,7 @@
 using Deltares.DamEngine.Io.XmlInput;
 using Deltares.Geometry;
 using Deltares.Geotechnics.Soils;
+using Deltares.Standard.Extensions;
 using SoilProfile2D = Deltares.Geotechnics.Soils.SoilProfile2D;
 using XMLSoilProfile2D = Deltares.DamEngine.Io.XmlInput.SoilProfile2D;
 using XMLSoilLayer2D = Deltares.DamEngine.Io.XmlInput.SoilProfile2DLayer2D;
@@ -40,13 +41,14 @@
     public static class XMLSoilProfile2DConverter
     {
         /// <summary>
-        /// Creates a new instance based on <paramref name="soilProfile"/>.
+        /// Converts the <paramref name="soilProfile"/> to a new instance of <see cref="XMLSoilProfile2D"/>.
         /// </summary>
-        /// <param name="soilProfile">The <see cref="SoilProfile2D"/> to create a
-        /// <see cref="XMLSoilProfile2D"/> for.</param>
+        /// <param name="soilProfile">The <see cref="SoilProfile2D"/> to convert.</param>
         /// <returns>A <see cref="XMLSoilProfile2D"/>.</returns>
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="soilProfile"/>
         /// is <c>null</c>.</exception>
+        /// <exception cref="ConversionException">Thrown when <paramref name="soilProfile"/>
+        /// could not be successfully converted.</exception>
         public static XMLSoilProfile2D Convert(SoilProfile2D soilProfile)
         {
             if (soilProfile == null)
@@ -71,30 +73,53 @@
             return convertedSoilProfile;
         }
 
+        /// <summary>
+        /// Converts the input arguments to a new instance of <see cref="XMLSoilLayer2DSurface"/>.
+        /// </summary>
+        /// <param name="soilLayer">The soil layer to convert.</param>
+        /// <returns>A <see cref="XMLSoilLayer2D"/>.</returns>
+        /// <exception cref="ConversionException">Thrown when <see cref="XMLSoilLayer2DSurface"/>
+        /// could not be successfully created from <paramref name="soilLayer"/>.</exception>
         private static XMLSoilLayer2D ConvertSoilLayer(SoilLayer2D soilLayer)
         {
+            string soilLayerName = soilLayer.Name;
             var convertedLayer = new XMLSoilLayer2D
             {
-                SoilName = soilLayer.Name,
-                IsAquifer = soilLayer.IsAquifer
+                SoilName = soilLayerName,
+                IsAquifer = soilLayer.IsAquifer,
+                WaterpressureInterpolationModel = 2 // Corresponds with the 'hydrostatic' value in DSoilModel
             };
 
             GeometrySurface surface = soilLayer.GeometrySurface;
-            convertedLayer.Surface = ConvertSGeometrySurface(surface);
+            convertedLayer.Surface = ConvertGeometrySurface(soilLayerName, surface);
 
             return convertedLayer;
         }
 
-        private static XMLSoilLayer2DSurface ConvertSGeometrySurface(GeometrySurface surface)
+        /// <summary>
+        /// Converts a <see cref="GeometrySurface"/> to a <see cref="XMLSoilLayer2DSurface"/>.
+        /// </summary>
+        /// <param name="layerName">The name of the layer to create a xml soil layer surface for.</param>
+        /// <param name="surface">The surface to create a xml soil layer surface for.</param>
+        /// <returns>A <see cref="XMLSoilLayer2DSurface"/>.</returns>
+        /// <exception cref="ConversionException">Thrown when <see cref="XMLSoilLayer2DSurface"/>
+        /// could not be successfully created from <paramref name="surface"/>.</exception>
+        private static XMLSoilLayer2DSurface ConvertGeometrySurface(string layerName, GeometrySurface surface)
         {
             var convertedSurface = new XMLSoilLayer2DSurface
             {
-                OuterLoop = ConvertOuterLoop(surface.OuterLoop.Points),
+                OuterLoop = ConvertOuterLoop(surface.OuterLoop.Points)
             };
 
-            // TODO: throw exception when there are more inner loops
             var innerLoop = surface.InnerLoops;
-            convertedSurface.Innerloop = !surface.InnerLoops.Any() 
+            int nrOfInnerLoops = innerLoop.Count;
+            if (nrOfInnerLoops > 1)
+            {
+                // Note that the exception message does not match of what is being asserted. 
+                throw new ConversionException($"{layerName} contains more than 1 inner loop.", null); 
+            }
+            
+            convertedSurface.Innerloop = nrOfInnerLoops == 0
                 ? new XMLSurfaceInnerPoint[0] 
                 : ConvertInnerLoop(innerLoop.Single().Points);
             
Index: DamClients/DamUI/trunk/src/Dam/Tests/DamEngineIo/XMLSoilProfile2DConverterTest.cs
===================================================================
diff -u -r3034 -r3043
--- DamClients/DamUI/trunk/src/Dam/Tests/DamEngineIo/XMLSoilProfile2DConverterTest.cs	(.../XMLSoilProfile2DConverterTest.cs)	(revision 3034)
+++ DamClients/DamUI/trunk/src/Dam/Tests/DamEngineIo/XMLSoilProfile2DConverterTest.cs	(.../XMLSoilProfile2DConverterTest.cs)	(revision 3043)
@@ -25,6 +25,7 @@
 using Deltares.Dam.Data.DamEngineIo;
 using Deltares.Geometry;
 using Deltares.Geotechnics.Soils;
+using Deltares.Standard.Extensions;
 using NUnit.Framework;
 using SoilProfile2D = Deltares.Geotechnics.Soils.SoilProfile2D;
 using XMLSoilProfile2D = Deltares.DamEngine.Io.XmlInput.SoilProfile2D;
@@ -38,7 +39,6 @@
     [TestFixture]
     public class XMLSoilProfile2DConverterTest
     {
-
         [Test]
         public void Convert_SoilProfileNull_ThrowsArgumentNullException()
         {
@@ -53,21 +53,14 @@
 
         /// <code>
         /// -------------------------------------------------------------
-        /// Layer three
+        /// Layer Two
         ///      |----------------------------------------------------|
         ///      |                                                    |
         ///      |                                                    |
         ///      |                                                    |
         ///      |----------------------------------------------------|
         /// 
         /// -------------------------------------------------------------
-        /// Layer two
-        ///      |------------------------|    |---------------------|
-        ///      |                        |    |                     |
-        ///      |                        |    |                     |
-        ///      |------------------------|    |---------------------|
-        ///
-        /// -------------------------------------------------------------
         /// Layer one
         ///
         ///
@@ -92,49 +85,27 @@
             var layerTwo = new SoilLayer2D
             {
                 Name = "LayerTwo",
-                IsAquifer = true,
-                GeometrySurface = new GeometrySurface()
-            };
-//            layerTwo.GeometrySurface.InnerLoops.AddRange(new []
-//            {
-//                CreateLoop(new GeometryPoint(6, 0, -9),
-//                    new GeometryPoint(9, 0, -9),
-//                    new GeometryPoint(6, 0, -6),
-//                    new GeometryPoint(9, 0, -6)),
-//                CreateLoop(new GeometryPoint(1, 0, -9),
-//                    new GeometryPoint(4, 0, -9),
-//                    new GeometryPoint(1, 0, -6),
-//                    new GeometryPoint(4, 0, -6))
-//            });
-            layerTwo.GeometrySurface.OuterLoop = CreateLoop(new GeometryPoint(0, 0, -10), 
-                new GeometryPoint(10, 0, -10), 
-                new GeometryPoint(0, 0, -5), 
-                new GeometryPoint(10, 0, -5));
-
-            var layerThree = new SoilLayer2D
-            {
-                Name = "LayerThree",
                 IsAquifer = false,
                 GeometrySurface = new GeometrySurface()
             };
-            layerThree.GeometrySurface.InnerLoops.AddRange(new[]
+            layerTwo.GeometrySurface.InnerLoops.AddRange(new[]
             {
                 CreateLoop(new GeometryPoint(6, 0, -4),
                     new GeometryPoint(9, 0, -4),
                     new GeometryPoint(6, 0, -1),
                     new GeometryPoint(9, 0, -1))
             });
-            layerThree.GeometrySurface.OuterLoop = CreateLoop(new GeometryPoint(0, 0, -5),
-                new GeometryPoint(10, 0, -5),
+            layerTwo.GeometrySurface.OuterLoop = CreateLoop(new GeometryPoint(0, 0, -10),
+                new GeometryPoint(10, 0, -10),
                 new GeometryPoint(0, 0, 0),
                 new GeometryPoint(10, 0, 0));
 
             var soilProfile = new SoilProfile2D
             {
                 Name = "SoilProfile2D"
             };
+            soilProfile.Surfaces.Add(layerOne);
             soilProfile.Surfaces.Add(layerTwo);
-            soilProfile.Surfaces.Add(layerThree);
 
             // Call
             XMLSoilProfile2D convertedProfile = XMLSoilProfile2DConverter.Convert(soilProfile);
@@ -151,12 +122,55 @@
             }
         }
 
+        [Test]
+        public void Convert_SoilProfileContainsSoilLayerWithTwoInnerLoops_ThrowsConversionException()
+        {
+            // Setup
+            const string invalidLayerName = "invalidLayer";
+            var invalidLayer = new SoilLayer2D
+            {
+                Name = invalidLayerName,
+                IsAquifer = true,
+                GeometrySurface = new GeometrySurface()
+            };
+            invalidLayer.GeometrySurface.InnerLoops.AddRange(new []
+            {
+                CreateLoop(new GeometryPoint(6, 0, -9),
+                    new GeometryPoint(9, 0, -9),
+                    new GeometryPoint(6, 0, -6),
+                    new GeometryPoint(9, 0, -6)),
+                CreateLoop(new GeometryPoint(1, 0, -9),
+                    new GeometryPoint(4, 0, -9),
+                    new GeometryPoint(1, 0, -6),
+                    new GeometryPoint(4, 0, -6))
+            });
+            invalidLayer.GeometrySurface.OuterLoop = CreateLoop(new GeometryPoint(0, 0, -10),
+                new GeometryPoint(10, 0, -10),
+                new GeometryPoint(0, 0, -5),
+                new GeometryPoint(10, 0, -5));
+
+            var soilProfile = new SoilProfile2D
+            {
+                Name = "SoilProfile2D"
+            };
+            soilProfile.Surfaces.Add(invalidLayer);
+
+            // Call
+            TestDelegate call = () => XMLSoilProfile2DConverter.Convert(soilProfile);
+
+            // Assert
+            Assert.That(call, Throws.Exception.TypeOf<ConversionException>()
+                .With.Message.EqualTo("No soil assigned contains more than 1 inner loop."));
+        }
+
         private static void AssertLayer(SoilLayer2D soilLayer, XMLSoilLayer2D convertedSoilLayer)
         {
             Assert.That(convertedSoilLayer.SoilName, Is.EqualTo(soilLayer.Name));
             Assert.That(convertedSoilLayer.IsAquifer, Is.EqualTo(soilLayer.IsAquifer));
-            Assert.That(convertedSoilLayer.WaterpressureInterpolationModel, Is.EqualTo(0)); // Water pressure interpolation model is not instantiated.
 
+            // Water pressure interpolation model should be set to Hydrostatic as default (which is value = 2 in DSoilModel)
+            Assert.That(convertedSoilLayer.WaterpressureInterpolationModel, Is.EqualTo(2)); 
+
             AssertSurface(soilLayer.GeometrySurface, convertedSoilLayer.Surface);
         }