Computational fluid dynamic (CFD) modeling was used to evaluate primary settling tank (PST) performance and a novel wet weather chemically enhanced high rate treatment (CE-HRT) tank configuration. Total suspended solids removal performance of three PST configurations under dry and wet weather conditions were evaluated using various baffling, launder, and sludge removal improvements. CFD modeling of wet weather treatment tanks with chemically treated raw influent showed CE-HRT can meet project requirements for wet weather flow discharges. The use of a combination of full-scale and bench-scale testing was employed to extend the application of the model to chemically treated influent.