The glass-smooth surface of CPP SMOOTH-CORE/n-10 HDPE (High-Density Polyethylene) plastic culvert pipe offers the potential of durable, long-term stable flow rates to pipe line design engineers. To achieve n-10 flow rates in the real world however, Civil Engineers must consider other non-pipe hydraulic factors such as the opportunity that water has for entering a pipe system. CPP Collector Headwall Inlets are devices used for improving the flow of surface waters into a gravity flow n-10 pipe system.

The arc in the COLLECTOR INLET eases the water flow into the outlet orifice.

The CPP SMOOTH-CORE/n-10 COLLECTOR INLET HEADWALL is designed to ease trench/ditch waters into CPP SMOOTH-CORE/n-10 pipe systems. The design avoids water recirculation type back-flows that slow down water entry into outlet pipes. Water back-flows occur when outlet pipe entranceways protrude into the water entry zone. These entry flow blockages will prevent CPP Smooth-Core pipes from reaching their n-10 water flow potential. Heavy sediment suspension in water flows can also reduce the hydraulic flow of CPP pipes. An erosion resistant sediment trap, constructed of stone at the discharge end of the collector headwall inlet can reduce sediment related water flow restrictions.