With six tiny rubber wheels and an inquisitive single eye, it looks a bit like the Mars rover vehicle, only tiny and dangling at the end of a wire. Spread over 300 acres (and surrounded by 1,200 acres of farm fields for application of biosolids), the plant is big enough that to see it you have to tool around in a van; you can't walk it like you can the water treatment plant miles upstream. One day I pulled over on a main highway to watch a sewer crew fix a leaky pipe using what's called cured-in-place pipe: A long liner impregnated with resin is pushed into a pipe by water, then they pump steam through the pipe to harden the resin, and presto--the pipe is, though slightly narrower, all but new. At the time, Mayor Brian Bowman warned of risks to Winnipeg’s sewage treatment system and possible environmental damage to Manitoba’s waterways if the phosphorus reduction measures were pushed forward without further study. Superintendent T. J. Lynch started my tour with a drive to the headworks, where screens and vortex filters remove the floating junk and grit from the outflow of the twin 72-inch trunks flowing in from the sewer system.

It started the process of making an emergency interconnection to the Lynnfield Water District, which is supplied by the MWRA. The floating stuff is more obvious, but Lynch emphasizes the basins that settle out grit: In a process heavy on pumps and pipes, grit is anathema. The lower the BOD, the smaller the next basins can be and the lower the plant's operating costs. Dave told me. "This makes it easier. A lot easier." They lay pipe on a bed of gravel, supporting it with rocks and pieces of brick to maintain the slope, unlike water pipe, which, under pressure, can just be laid in a trench and buried. You can tell when untreated wastewater has hit a stream, Smith says, by the powdery-looking buildup it leaves: "It looks like gray dust in the water," coating the rocks and sticks. The wastewater provides the food, the nozzles provide the oxygen, and the bacteria feel like they're on a cruise: nothing but breathing, eating, and reproducing, with free food all day long. But since the flow had to go downhill, the engineers had to get wastewater to flow away from the manhole in a different direction.

I had stopped by a sewer truck to watch a couple of guys hose out a pipe, which they followed to a manhole at the backyard boundary of a few properties. The vacuum nozzle can clear the manhole but can't pull grease out of the pipe and it resists everything else they've got, so the crew finally gives up on TV-ing that pipe for the day, until they can clean the pipe--possibly by using a bucket truck (which feeds a cable past the debris and drags a bucket from one manhole to the next, pulling before it the kind of grit and large debris flushing just doesn't get) or possibly by sending someone down there in the hope that a simple scoop into the pipe will clear the debris. The stuff turns out to be congealed grease, and pieces of it are sufficiently solid--and sufficiently far up the 6-inch pipe--that they block the progress of the camera every time the Rev dangles it down there and tries to get it running. A few moments of observation shows two things: The backup comes and goes rhythmically, meaning there's a pump station upstream that sends a pulse of wastewater every couple of minutes, and the blockage is a bunch of pieces of some solid substance that nobody can identify.

This kind of backup indicates a block in the 6-inch pipe at the bottom of the manhole, though it drains away as fast as it backed up. Workers can find leaks by stopping up pipes with sandbags, pumping smoke down a manhole, and then seeing where the smoke starts creeping out of the ground. Instead, the WS1 uses an improved manganese greensand because the coating doesn’t degrade, so it can last forever and doesn’t need chemical maintenance. Most industrial processes, such as petroleum refineries, chemical and petrochemical plants have their own specialized facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the regulations regarding disposal of wastewaters into sewers or into rivers, lakes or oceans. Iron and rust filter cartridges are cheaper than air and chemical injection systems, but they’re only suitable for moderate iron problems, and they have a limited filter lifespan of 3-6 months. You can get up to 10-15 years of high performance from the unit before it reaches the end of its lifespan. The most expensive filter on our list - the Pelican WF4 - is $3,300, but it removes more contaminants than the other filters and it has media that will last for about six years.

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