diff --git a/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMemberTranslatorPlugin.cs b/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMemberTranslatorPlugin.cs
index 7bb1d0959..473b95cb5 100644
--- a/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMemberTranslatorPlugin.cs
+++ b/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMemberTranslatorPlugin.cs
@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Linq.Expressions;
 using GeoAPI.Geometries;
 using Microsoft.EntityFrameworkCore.Query.Expressions;
@@ -18,6 +18,24 @@ public class NpgsqlNetTopologySuiteMemberTranslatorPlugin : IMemberTranslatorPlu
 
     public class NpgsqlGeometryMemberTranslator : IMemberTranslator
     {
+        static readonly CaseWhenClause[] _ogcGeometryTypeWhenThenList = new[]
+        {
+            new CaseWhenClause(Expression.Constant("ST_CircularString"), Expression.Constant(OgcGeometryType.CircularString)),
+            new CaseWhenClause(Expression.Constant("ST_CompoundCurve"), Expression.Constant(OgcGeometryType.CompoundCurve)),
+            new CaseWhenClause(Expression.Constant("ST_CurvePolygon"), Expression.Constant(OgcGeometryType.CurvePolygon)),
+            new CaseWhenClause(Expression.Constant("ST_GeometryCollection"), Expression.Constant(OgcGeometryType.GeometryCollection)),
+            new CaseWhenClause(Expression.Constant("ST_LineString"), Expression.Constant(OgcGeometryType.LineString)),
+            new CaseWhenClause(Expression.Constant("ST_MultiCurve"), Expression.Constant(OgcGeometryType.MultiCurve)),
+            new CaseWhenClause(Expression.Constant("ST_MultiLineString"), Expression.Constant(OgcGeometryType.MultiLineString)),
+            new CaseWhenClause(Expression.Constant("ST_MultiPoint"), Expression.Constant(OgcGeometryType.MultiPoint)),
+            new CaseWhenClause(Expression.Constant("ST_MultiPolygon"), Expression.Constant(OgcGeometryType.MultiPolygon)),
+            new CaseWhenClause(Expression.Constant("ST_MultiSurface"), Expression.Constant(OgcGeometryType.MultiSurface)),
+            new CaseWhenClause(Expression.Constant("ST_Point"), Expression.Constant(OgcGeometryType.Point)),
+            new CaseWhenClause(Expression.Constant("ST_Polygon"), Expression.Constant(OgcGeometryType.Polygon)),
+            new CaseWhenClause(Expression.Constant("ST_PolyhedralSurface"), Expression.Constant(OgcGeometryType.PolyhedralSurface)),
+            new CaseWhenClause(Expression.Constant("ST_Tin"), Expression.Constant(OgcGeometryType.TIN))
+        };
+
         public Expression Translate(MemberExpression e)
         {
             var declaringType = e.Member.DeclaringType;
@@ -86,8 +104,13 @@ public Expression Translate(MemberExpression e)
                     return new SqlFunctionExpression("ST_NumInteriorRings", typeof(int), new[] { e.Expression });
                 case "NumPoints":
                     return new SqlFunctionExpression("ST_NumPoints", typeof(int),       new[] { e.Expression });
+                case "OgcGeometryType":
+                    return new CaseExpression(
+                        new SqlFunctionExpression("ST_GeometryType", typeof(string),    new[] { e.Expression }),
+                        _ogcGeometryTypeWhenThenList);
                 case "PointOnSurface":
-                    return new SqlFunctionExpression("ST_PointOnSurface", typeof(IPoint), new[] { e.Expression });
+                case "InteriorPoint":
+                    return new SqlFunctionExpression("ST_PointOnSurface", typeof(IGeometry), new[] { e.Expression });
                 case "SRID":
                     return new SqlFunctionExpression("ST_SRID", typeof(int),            new[] { e.Expression });
                 case "StartPoint":
diff --git a/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMethodCallTranslatorPlugin.cs b/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMethodCallTranslatorPlugin.cs
index 1d3a030cc..91de01ce0 100644
--- a/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMethodCallTranslatorPlugin.cs
+++ b/src/EFCore.PG.NTS/Query/ExpressionTranslators/Internal/NpgsqlNetTopologySuiteMethodCallTranslatorPlugin.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
 using GeoAPI.Geometries;
@@ -43,7 +44,7 @@ public virtual Expression Translate(MethodCallExpression e, IDiagnosticsLogger<D
             case "AsText":
                 return new SqlFunctionExpression("ST_AsText",        typeof(string),   new[] { e.Object });
             case "Buffer":
-                return new SqlFunctionExpression("ST_Buffer",        typeof(Geometry), new[] { e.Object, e.Arguments[0] });
+                return new SqlFunctionExpression("ST_Buffer",        typeof(Geometry), new[] { e.Object }.Concat(e.Arguments));
             case "Contains":
                 return new SqlFunctionExpression("ST_Contains",      typeof(bool),     new[] { e.Object, e.Arguments[0] });
             case "ConvexHull":
@@ -91,7 +92,7 @@ public virtual Expression Translate(MethodCallExpression e, IDiagnosticsLogger<D
             case "Touches":
                 return new SqlFunctionExpression("ST_Touches",       typeof(bool),     new[] { e.Object, e.Arguments[0] });
             case "Union" when e.Arguments.Count == 0:
-                return null;  // ST_Union() with only one parameter is an aggregate function in PostGIS
+                return new SqlFunctionExpression("ST_UnaryUnion",    typeof(Geometry), new[] { e.Object });
             case "Union" when e.Arguments.Count == 1:
                 return new SqlFunctionExpression("ST_Union",        typeof(Geometry),  new[] { e.Object, e.Arguments[0] });
             case "Within":
diff --git a/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeographyTest.cs b/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeographyTest.cs
index 33e89b2a0..0a6da5723 100644
--- a/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeographyTest.cs
+++ b/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeographyTest.cs
@@ -53,6 +53,15 @@ public override async Task Buffer(bool isAsync)
 FROM ""PolygonEntity"" AS e");
         }
 
+        public override async Task Buffer_quadrantSegments(bool isAsync)
+        {
+            await base.Buffer_quadrantSegments(isAsync);
+
+            AssertSql(
+                @"SELECT e.""Id"", ST_Buffer(e.""Polygon"", 1.0, 8) AS ""Buffer""
+FROM ""PolygonEntity"" AS e");
+        }
+
         public override async Task Centroid(bool isAsync)
         {
             await base.Centroid(isAsync);
@@ -184,11 +193,13 @@ public override async Task ToText(bool isAsync)
         public override Task IsSimple(bool isAsync)                  => Task.CompletedTask;
         public override Task IsValid(bool isAsync)                   => Task.CompletedTask;
         public override Task Item(bool isAsync)                      => Task.CompletedTask;
+        public override Task InteriorPoint(bool isAsync)             => Task.CompletedTask;
         public override Task LineString_Count(bool isAsync)          => Task.CompletedTask;
         public override Task M(bool isAsync)                         => Task.CompletedTask;
         public override Task NumGeometries(bool isAsync)             => Task.CompletedTask;
         public override Task NumInteriorRings(bool isAsync)          => Task.CompletedTask;
         public override Task NumPoints(bool isAsync)                 => Task.CompletedTask;
+        public override Task OgcGeometryType(bool isAsync)           => Task.CompletedTask;
         public override Task Overlaps(bool isAsync)                  => Task.CompletedTask;
         public override Task PointOnSurface(bool isAsync)            => Task.CompletedTask;
         public override Task Relate(bool isAsync)                    => Task.CompletedTask;
diff --git a/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeometryTest.cs b/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeometryTest.cs
index a133f4c63..a53e23c72 100644
--- a/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeometryTest.cs
+++ b/test/EFCore.PG.FunctionalTests/Query/SpatialQueryNpgsqlGeometryTest.cs
@@ -59,6 +59,15 @@ public override async Task Buffer(bool isAsync)
 FROM ""PolygonEntity"" AS e");
         }
 
+        public override async Task Buffer_quadrantSegments(bool isAsync)
+        {
+            await base.Buffer_quadrantSegments(isAsync);
+
+            AssertSql(
+                @"SELECT e.""Id"", ST_Buffer(e.""Polygon"", 1.0, 8) AS ""Buffer""
+FROM ""PolygonEntity"" AS e");
+        }
+
         public override async Task Centroid(bool isAsync)
         {
             await base.Centroid(isAsync);
@@ -248,6 +257,15 @@ public override async Task GetPointN(bool isAsync)
 FROM ""LineStringEntity"" AS e");
         }
 
+        public override async Task InteriorPoint(bool isAsync)
+        {
+            await base.InteriorPoint(isAsync);
+
+            AssertSql(
+                @"SELECT e.""Id"", ST_PointOnSurface(e.""Polygon"") AS ""InteriorPoint"", e.""Polygon""
+FROM ""PolygonEntity"" AS e");
+        }
+
         public override async Task Intersection(bool isAsync)
         {
             await base.Intersection(isAsync);
@@ -393,6 +411,30 @@ public override async Task NumPoints(bool isAsync)
 FROM ""LineStringEntity"" AS e");
         }
 
+        public override async Task OgcGeometryType(bool isAsync)
+        {
+            await base.OgcGeometryType(isAsync);
+
+            AssertSql(
+                @"SELECT e.""Id"", CASE ST_GeometryType(e.""Point"")
+    WHEN 'ST_CircularString' THEN 8
+    WHEN 'ST_CompoundCurve' THEN 9
+    WHEN 'ST_CurvePolygon' THEN 10
+    WHEN 'ST_GeometryCollection' THEN 7
+    WHEN 'ST_LineString' THEN 2
+    WHEN 'ST_MultiCurve' THEN 11
+    WHEN 'ST_MultiLineString' THEN 5
+    WHEN 'ST_MultiPoint' THEN 4
+    WHEN 'ST_MultiPolygon' THEN 6
+    WHEN 'ST_MultiSurface' THEN 12
+    WHEN 'ST_Point' THEN 1
+    WHEN 'ST_Polygon' THEN 3
+    WHEN 'ST_PolyhedralSurface' THEN 15
+    WHEN 'ST_Tin' THEN 16
+END AS ""OgcGeometryType""
+FROM ""PointEntity"" AS e");
+        }
+
         public override async Task Overlaps(bool isAsync)
         {
             await base.Overlaps(isAsync);
@@ -508,8 +550,14 @@ 1 1
 FROM ""PolygonEntity"" AS e");
         }
 
-        [ConditionalTheory(Skip="ST_Union() with only one parameter is an aggregate function in PostGIS")]
-        public override Task Union_void(bool isAsync) => null;
+        public override async Task Union_void(bool isAsync)
+        {
+            await base.Union_void(isAsync);
+
+            AssertSql(
+                @"SELECT e.""Id"", ST_UnaryUnion(e.""MultiLineString"") AS ""Union""
+FROM ""MultiLineStringEntity"" AS e");
+        }
 
         public override async Task Within(bool isAsync)
         {