Blog #359 Colville Waste Treatment plant

 I was trying to come up with a cute title that wouldn't offend the few folks that read my blog, but just gave up.

I called Scott, who runs the plant with one other person, about a tour of his facilities and got a quick answer...sure come on down. I get the feeling they don't get many people wanting to walk around a sewage plant.

I met Scott in the analyzing room where tests are constantly being done to the water samples. Water is tested coming into the plant, as well as leaving, after the final process. 

Scott gave me a tour of the office area, lunchroom, drinking faucets (no thank you) and the lab. The reason they only need two full time employee's (plus one seasonal) is because nearly everything is automated. He can see and control all of the flows, discharges, ponds and pumps from this office and computer. 

The treatment plant is fairly new, built in 2007, and I was surprised at how clean the whole property was.

This is the room where it all starts, called the "head works building". Most of the waste is gravity fed from town, but the city does have 7 area's where a pump is used the get the effluent to the plant. The sewage flows freely to this device in the center of the room, it's called a Muffin Monster. There are two grinders and a brush where the fluid initially must pass to grind the material to a fine sand and remove the heaviest items in the flow. Scott says that Handi Wipes and male diapers cause the most problems. Handi Wipes because they are made of a slick material and male diapers, because of embarrassment, men will flush these down the toilet instead throwing them into a garbage can. This was the only room that had an unpleasant smell.

I am standing next to three pumps, located in the influent lift station, that pump the sewage from the muffin monster room uphill to the head of the 20 acre plant. I asked about future growth in the town and its effect on capacity and was told that in ten years, Colville has lost population and projections of future growth were nil. The plant can handle 1.45 million gallons a day and at present handles an average of 0.8 million. 

Here in the preliminary treatment building, there are two screening devices that take out the last bits of cloth, paper, sand and dump them into the large garbage dumpster.  

After the preliminary treatment building, the waste flows into these large two story selector tanks. There are good microbes and bad microbes and the only way to get rid of the bad is to kill all...by eliminating the oxygen. The average flow coming into the plant is about 580 gallons per minute.

Here is the companion tank (there are four) that is empty and you can see the mixer at the bottom. 

After the selector tanks the waste (devoid of microbes) flows into the aeration basin S curves and it is here that only good microbes are reintroduced to feed on the bad bacteria. 

After the aeration tanks the fluid goes into one of the two round clarifiers. As you might be able to tell, the water is already becoming much clearer. 

Here is the other clarifier that was empty at the time. The center device continues to slowly go around, mixing the fluid.

After flowing through the clarifiers the fluids are exposed to these UV light systems, much like I had with our Koi pond. The UV lights don't kill microorganisms, but makes them immediately sterile.

At this point, the fluid coming out of the UV room is sent straight to the Colville River. Despite not quite drinking quality, it does meet all federal laws for discharge into a waterway. The discharge is around 540 gallons per minute, the missing 40 gallons go into a settling pond.

  The small percentage of dead microbes and bacteria equal less than 10 percent of the inflow or about 40 gallons per minute. That 10 percent is pumped to the pond basins and evaporation keeps the pond level. There are 4 of these large ponds on 40 acres and only one with water in it. Because of redundancy, if the plant stopped working they would be able to use the three remaining ponds as catch basins allowing the city two weeks to correct any problem.

I asked about freezing in the winter causing problems? No, because nearly everything is in buildings, or underground, the winter does not slow the plant down other than the big pond freezing over.

Thanks to Scott for taking the time for me today.

Me? I live three miles from town and am on a septic system so while it is of interest to me...it does me no good.

Can't end a blog without a deer photo. This guy was on the side of the trail today where I walk in the morning and very unconcerned at my presences.