CVR Operations

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When it comes to working at a wastewater plant, operations is one of my strong suits. I seem to have a natural flair for understanding the needs of a wastewater plant and making it work to the best of its ability. I attribute this to the excellent training I've received, my exposure to several different types of operations early in my career, and to my keen mathmaticals skills (something extremely important for wastewater). All of these skills serve me well on the water side too.

Villa Rica's wastewater treatment plants are poorly designed. In addition, a significant portion of the influent flow comes from large industries with high waste loads. This combination has resulted any many problems over the years making operations quite a challenge.

The North Plant is based on a solid design. The main process is a carousel followed by circular clarifiers and these tanks have excellent design parameters. Unfortunately, the number of drying beds installed was too small to handle the load and there's no digester at all. The city eventually installed a belt press to dewater the solids and they are about to build a digester. Once completed, this facility should have very few problems in the future.

I can't say whether or not the West Plant is a good design because its original design was based on a process I've never heard of and could not find in any information about. The project engineer claimed it was a well documented design type but never supplied the city with the names of any reference materials despite our repeated requests. We followed his operational instructions and tried to make the facility work but it failed from the start and continuously broke permit until we hired another firm to help us figure out a way to fix it.

The original design of the expansion was for a two-part secondary treatment process (no tertiary treatment). Our fix was to install a new line which returned the sludge from the second part back to the first part creating a more conventional all-in-one process. The results of this change were immediate and significant.

However, while this change gave us a treatment process we actually understood, there were so many other design flaws that it was impossible to overcome all of them all of the time. First there were the insufficient detention times, both in the aeration basins and the digestors. Next was the hydraulic problems such as the inability to ensure that flows were split evenly between processes and short circuiting problems. And finally, like the North Plant, this plant was not given sufficient drying bed space to handle the load. The city eventually installed a belt press here as well.

As mentioned earlier, another issue that has an impact on operations is the city's industries. Our industrial pretreatment program has gone a long way towards making sure we can handle what we receive at the plant. However, when a single industry exceeds ten percent of your daily flow and that industry has a bad day, the plant has a bad day too.

In the long run, as an operator you have to recognize problems like these and figure out a way to fix them or work around them. In the case of the West Plant, true fixes would have been prohibitively expensive so for the last decade and a half, the operational staff has mostly had to handle the problems with work arounds. Some of the fixes have been simple such as jamming drop gates in odd positions to force flows to split correctly between different tanks. Some of them have been more complex such as building a home grown polymer feed system to control clarifier blankets then conducting trials to determine the best product for the best results. There have been many others, not all of which I personally thought of, but through their efforts the operational staff definitely pulled the fat out of the fire many more times than the environment got burned.

For almost a decade prior to the current economic downturn, Villa Rica experienced explosive growth. This also had an impact on the West Plant, increasing the load on an already stressed out system. When that happened, city hall made the right choice - replace the plant. Unlike its predecessors, the new West Plant is a solid design that will serve the city well. At least it better. I was intimately involved in its design working directly with the engineer on the project for over two years. I can't wait to see it in operation.

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