This drain was a fantastic find; the first duct-type drain we've explored in Edmonton.
The ouftall for this drain is, according to the city, 25 x 13 feet; a huge, corrugated oval on its side. A waterfall, weir, and large gate are the obstacles to entry at the huge outfall, not to mention the water flow. Inside, it's a big, wide-open space of corrugated pipe that runs for about 100m before reducing to a fantastic concrete duct. There's a remote flow monitoring station near the gate, don't fuck with it.
For the unfamiliar, duct is concrete cast in a square or rectangular shape; as opposed to RCP (reinforced concrete pipe), which is round. While omnipresent in Calgary, duct is so far rarely found in Edmonton, being used only for storage tanks. Hence, I was very excited when we found this.
The duct's size is also impressive; for the entire length, it's about 5m wide by 3m tall; you could literally drive a pickup inside this. Midway down it, a 1650 pipe comes in. We followed this until it started getting smaller; there's nothing there, so we went back to the wonderful duct. Although [the duct] isn't terribly long, it runs for probably 300m before it comes to its (also spectacular) end.
The duct's ending is in the form of a branch in a huge room, with an inflow from a creek to the left and a big waterfall to the right. The room is tall, probably 4m high, and about 8m wide. A small wall divides the creek inflow (to the left) and the waterfall (to the right). The creek inflow is about a 1350 horizontal eye(oval) pipe, that comes into the room via a tiny slide.
To the right of this is the waterfall, which takes up almost the entire room. The water falls onto a sloped floor, which forms a deep pool and is separated by a weir from the rest of the room (do not step into this pool, it is really deep. The water comes down with a vengeance, and throws out a lot of spray; the entire room is misty.
We've also explored the drain which leads to the top of this waterfall, named To The End of the World.
This waterfall is really loud, and you can hear it down the entire section of duct, and 350m away, near the outfall. It sounds like thunder, and the duct is big enough to be a road, and the drain was named.
This drain would be very dangerous to do anytime after rain; I imagine the flow would be tremendous. A drain this big is built to handle huge, heavy flow; so stay out!
I decided to head back into Thunder Road to check how it was doing. I'd already explored the entire thing the first trip (see Thunder Road) but I wanted some better photos, and did I mention how much I love square pipe?
The drain was pretty much exactly the way I remembered it, but the size of the pipe was still amazing. I even blurted out "holy shit" when I entered the waterfall chamber; that place is freakin' huge, and most impressive. The waterfall thunders non-stop, 24/7, year round, filling the chamber with misty droplets. I didn't want to expose my nice camera to that, so no photos this time.
Near the outfall end, there have been a few "additions" involving spraypaint, but most of the drain is still plain concrete wall. The corrugated pipe and outfall gate are still solid, but the flow sensor has taken a beating, and is ripped up. The power plant across the river, lit up with yellowish floodlights, is a wonderful thing to behold at night.
Headed back inside once again, for better photos. And I know I'll be back again, sooner or later.