A modular trench drain system with sloping overlay rails. A non-sloping section of trench drain is transformed into a sloping trench drain by installing sloping overlay rails. The overlay rails rest on the top of the upper edge of the sidewalls and may have a ledge which allows grating, which spans across the channel, to rest on top. The modular channels sections may be held together and in place by a clip with holes for accepting support rods which further secure the channels in place before and after the concrete has been poured and cured around the channels.