The dimension relationships for the Semi-elliptical conduit shape is shown below, this chart is referenced from the EPA SWMM manual. Basket-handle. Note: Width 4.6 Final Hydraulic Model digital files, training manual, Modeler's Notebook,. Downtown trunk system capacity improvement technical memorandum. components of the Wastewater Collection and Transmission System (WCTS). extension of ArcGIS, or as a stand-alone version (InfoSWMM® SA).