Steel pile foundations are optimized to find least weight systems. The pile cross-sections and orientations (batters) are optimized using an optimality criteria approach. The Lagrange multipliers are found using linear simultaneous equations with an innovative approach for assuming which constraints are active. The handling of topological variables by the optimality criteria approach is thoroughly discussed. The placement of the local coordinate systems for topological variables affects the convergence of the design. The examples are for a retaining wall for which a two-dimensional pile layout can be used to represent a segment of the wall. The algorithm quickly converges to a final design. All of the applied constraints are precisely controlled. It is demonstrated that the pile slope problem has locally optimal designs.