The top may include a slab of {HEAD ~ water impermeable material} having a substantially central opening through which plant material grows, as well as {TAIL ~ an inlet opening} for receiving stormwater to be treated 
The top may include a slab of { HEAD ~ water impermeable material } having a substantially central opening through which plant material grows , as well as { TAIL ~ an inlet opening } for receiving stormwater to be treated
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH