Chapter Two: Oh Look, A Casual Treatment Plant (feat. Steve Camp, Steve, Brian, Guest Appearance - Corey Hartman)

"Thanks for the ride, Mr. Camp!" I struggle to carry the two-gallon container full of lake water as I walk up my driveway. Holy moley, this is heavy.

This week was one for the ages. Aside from continuing research (which I'll detail in the next blog entry, not this one), I got the opportunity to head out to Lake Mary and the Lake Mary Water Treatment Plant to take a sample of the water and to tour the plant.

The Sample

To take the sample, we drove out to Lower Lake Mary to a little building with pipelines running from Upper Lake Mary and the Lake Mary wells. I had always thought that taking samples involved getting water-friendly shoes on (especially the ones where your toes are separated) and going into the water to fill your sampling container. As cool as that sounds, the sophistication of most treatment plants today allows for sampling to be much simpler, much quicker, and much more reliable.

Those blue pipes go to the Lake Mary wells...

And these green ones come from Upper Lake Mary.

Funnily enough, Lower Lake Mary was full of water due to all of the snow melt and precipitation over the past couple of weeks. Unfortunately, Lower Lake Mary is usually empty, so the water that's collected for treatment has to travel nine miles through pipes from Upper Lake Mary.

To take the sample, all we had to do was twist a little handle to open a spout. If you look up at the second picture, you can see the spout near the bottom right.

The sample! Two gallons of turbid, murky lake water.

The Tour

After we took the sample, I took a tour of the Lake Mary Water Treatment Plant. Here's how the process goes:

(1) The water travels nine miles from Upper Lake Mary to that little building, where the water is collected and transported another nine miles to the plant.

(2) The water is disinfected by chlorine dioxide.

(3) Coagulants are added to the water. Over a process of around six hours, the floc (a mass of fine particles) in the water collects and sinks to the bottom, turning into sludge. The water turns from high turbidity water (recently, around 125 NTU before the snowmelt this winter; around 60 NTU after the snowmelt) into low turbidity water (at the end of the six hours, around 1.5-2 NTU).

The "holding tank," where water gently flows and floc clumps into sludge.

(4) Water moves to filtration through andesite and sand, where the rest of the particles are separated from the water. After this stage, the water will reach a turbidity of about 0.04 NTU (for reference, the EPA requires that potable water from surface water sources is at 0.3 NTU or less, so Flagstaff's water is really clean and clear!)

My apologies for my reflection... The top layer is the andesite, the bottom layer is the sand.

(5) The water is transferred through pipes to UV disinfection.

The pipe system below the andesite/sand filtration tank.

The U.V. unit for disinfection. Flagstaff isn't required to use this, but it does as an extra measure to ensure that the water is as clean as possible!

(6) And finally, the water is chlorinated again as an extra measure against contamination during distribution (when the water leaves the holding tank at the treatment plant and is distributed to the public). The EPA requires that potable water from surface water sources has a chlorine residual concentration of at least 0.2 mg/L, but the water leaving the Lake Mary Water Treatment Plant has a chlorine residual concentration of 0.9-1 mg/L.

Essentially, the City of Flagstaff is going the extra mile to ensure clean water (at monetary costs).

And that's the Lake Mary Water Treatment Plant! This next coming week, I'll continue my research and, hopefully, will be able to analyze the sample of water that I took. Unfortunately, the things I want to test for in the water - organic pollutants, minerals, etc. - can't be tested at the Lake Mary Water Treatment Plant Laboratory because the lab currently isn't licensed to test for those. At the lab, they test for total coliforms (bacteria).

Special thanks to my external advisor, Steve Camp, for taking me to the plant and to the sampling location, as well as Brian and Steve from the water treatment plant for helping me take the sample and for giving me a tour of the plant! Also, shoutout to Ms. Hartman for her guest appearance this week (she knows!)

Looking forward to the next week of this project! It's starting to heat up.

End of Chapter Two.