§ 7.1. Introduction

The street system, roadside ditch, swale or channel may direct flow into an inlet, grate, or other collection structure into the storm drain system. This storm drain system will be comprised of inlets, pipes, junction boxes, bends, outlets, and other appurtenances. These systems may include water quality devices to meet state and federal water quality standards. This chapter describes the general guidelines needed to provide an adequate storm drain system and minimize impacts to both upstream and downstream properties.

The following shall be considered during the design of the storm drain systems.

For all ordinary conditions, storm drains shall be designed on the assumption that they will flow full under the design discharge; however, when there are constrictions, turns, submerged, or inadequate outfall, etc., the hydraulic and energy grade lines shall be computed and plotted in profile. The Energy Grade Line (EGL) shall be below the top of curb and the Hydraulic Grade Line (HGL) shall be below the gutter elevation of the drainage structure. In all cases adequate outfalls shall be provided, including review of point source discharges.

The EGL and HGL will be required on all storm drain systems.