Category Archives: Water Treatment Plants

Water

Colorado River Basin

I spent thirty years in the water business.  I was one of the troops, not a manager or staff person.  I did, however, do what I could to keep up with developments in the water and wastewater business.  With the Clean Water Act and the Environmental Protection Agency, rivers no longer catch fire, and our fresh water. Supply is in much better shape than, say, the 1950’s. 

I worked at the Greeley, Colorado wastewater plant for three years.  The water we sent to the river met EPA standards until the Cache La Poudre flooded and washed out the pipe carrying water from one side of the river to the other for final treatment.  Lots of raw sewage went into the river for about a week until an emergency pipeline was laid on the highway bridge next to the plant.   

An old adage in the wastewater business goes, “The solution to pollution is dilution”.  That saying is mostly obsolete, but during that flood there was plenty of water for dilution.  We had to wear hip waders to get around the north side of the plant, flooded with almost three feet of water.   

The Denver Water System

Here is a big part of the water story in the American West.  There is either too much water or not enough.  Here on the Colorado Front Range a water crisis is slowly developing.  The available water is starting to run out.  Half of Denver Water’s water supply comes under the Continental Divide from the Colorado River.  There is little more water available from the river for the Denver Metro population except from spring runoff, when there is more water than can be stored.  Most years.   

Other years, the snowpack is down, spring runoff is low, reservoirs drop, and worry starts.  Water supply fluctuates, but demand only increases.  Oh, wait, during a big drought recently,  the Denver Water Board shifted its priority from dam building and water diversion to conservation.  It worked, and continues to work, not just with Denver.  Another water source is also coming into use.   

Water law says if you use water from your nearby stream, you must return what you didn’t use to the stream.  Water users downstream get lots of their water from return flows from irrigation or wastewater plant outflows.  Water law also states that water you divert from another basin does not have to be returned.  You can use it to extinction.  So what once went downstream is being captured in new reservoirs downstream made from old gravel pits and used for water exchanges, where downstream users trade their upstream water rights for return flow water from Denver.  The potato and corn fields don’t seem to mind.   

The other thing happening is taking that foreign water, treating it, and pumping it upstream for reuse.  At this point it is mostly for irrigation of parks, golf courses, and the like, but it is also being treated to drinking water standards.  Yes, you might be drinking water that once was sewage.  Not to worry, think about Omaha, St. Louis, Memphis, and New Orleans.  What are they drinking? 

Eventually this will all end.  The water will run out.  At some point, tap fees for new housing or industry will soar and development will go elsewhere.  The growth cannot continue indefinitely.  The same thing will occur in the entire Colorado River Basin.  Despite every effort to conserve or store more water, it is going to run out.  The new growth will then go to Cincinnati and Birmingham, all those wet places back East..  They have lots of water.

Cleaning the Water

Building The Marston Plant a While Back

Building The Marston Plant a While Back

I spent 30 years in the water treatment industry.  Most of it was water treatment, but I put in three years in as a wastewater treatment operator.  The goal of both jobs is to make dirty water clean.  The processes are different, and the standards for the product differ, but the idea is to make the water safe for humans.   I wouldn’t recommend drinking wastewater plant effluent, but you can swim in it.  Water, you can drink, except in Flint. 

What about the stuff taken out of the water in order to make it safe?  In both instances the stuff is called sludge.  Sludge is nasty.  There are several kinds of wastewater sludge, some nastier than others.  The first step takes out the stuff that sinks.  In a wastewater plant,  that stuff is the nastiest.  I once fell in a pit of primary sludge, injured a finger, and lost it to infection.  In Spanish, my nickname is Nueve.    

There are several techniques to deal with wastewater sludge to render it more benign, but it still tends to stink.  (By any other name, it’s still shit.).  That sludge ends up on farmland or as compost.  Water plant sludge is treated differently, but gets used the same way. 

Water Filters

Water Filters

I spent sixteen years with Denver Water in the Marston treatment plant.  It is fed by Marston Lake with water from the South Platte River.  Most of the time South Platte water is high quality Rocky Mountain water.  At other times, the Rockies get unruly and send some dirty stuff down.  The treatment plants have to handle it all.  Water treatment is known as a physical-chemical process.  A chemical, usually aluminum sulfate is added to the water to make bigger pieces out of the sometimes microscopic pieces that must be removed (bacteria, viruses, cysts, silt, etc.). 

Then, the water goes into a big tank where those bigger pieces tend to sink to the bottom.  Machinery of some sort scrapes the settled sludge out and sends it to be treated further. 

The settled water then goes to the filters where almost everything is removed.  Next step, chlorine to kill all the little nasties that make people sick.  Then it goes down the pipe to town. 

Sludge

Sludge

What about all the sludge?  Lots of things are in the lake water.  Birds, fish, even small organisms create waste products that can be dangerous as well as unpleasant (shit).  It is mostly water, but the solids have to be dealt with.  At Marston, it goes into a big underground tank and accumulates until it gets removed, dewatered, and hauled away for compost making. 

The tank is 20 feet deep, 50 feet wide, and about 150 feet long.  After accumulating for a year, the tank is about six feet deep with sludge.  Now, water plant sludge is not as nasty as wastewater sludge.  Some of it is chemical, clay minerals as the end product of all that aluminum sulfate.  But, there are lots of organics as well.  When they sit for much of a year in an airless environment, they decompose into stinky stuff.  That stinky stuff also gives off hydrogen sulfide gas (the rotten egg smell).  H2S and water make sulfuric acid, not good for lungs. 

To get rid of that huge gob of stuff, we had to get down there with fire hoses, air monitors, and gas masks.  Nasty work and a contrast with our normal routine of lab work, monitoring the computerized systems, and doing routine maintenance.  Dirty work with those hoses, but kind of fun as well. 

Belt Filter Press

Belt Filter Press

We used those hoses to carve sludge.  We would make channels, wash down walls of goo, bore holes, make it spatter our coworkers, and other exciting activities.  The whole process took a couple of days.  The sludge then went to a thickener eh are much of the water drained off the surface and the sludge drained out the bottom.  Then, on to the belt filter press.  That thing looks like a big printing press.  The sludge goes between two five foot wide belts that go over and under a succession of rollers that squeeze much of the water out.  The resulting cake goes up into big hoppers and then into trucks, and hauled to the compost making facility.  In the old days all that stuff went into the river.  Now, it is a useful product. Pretty cool, eh?

 

More On Flint Water

Flint Water

Flint Water

The tragedy of Flint, Michigan water continues.  Most people in our country take water for granted.  Turn the handle and clean, safe water comes out.  There is a bill to pay every quarter or month, but it is not very expensive.  If you are having paying, the water provider will work with you. 

When a Flint resident turns the handle, red, turbid water high in lead comes out.  It is not safe to drink and is dangerous for bathing and dishwashing.  When it is water bill time, Flint has the highest water rates in the country.  People are paying a lot of money to damage their brains. 

There was a Legionnaires Disease outbreak which killed nine people and sickened many others.   Legionnaires Disease is waterborne, usually from the aerosol from showers in buildings  using a recirculating warm water system using cooling towers or rooftop storage tanks.  The bacterium is often present in drinking water along with other bacteria and viruses in low numbers.  

Disinfection in water treatment is intended to kill pathogenic organisms in the water.  It does not sterilize the water.  Given proper conditions, those organisms can multiply enough to pose a public health problem.     The big ones are the cooling towers and storage tanks.  Another potential source are the rusty accumulations called tubercles in old cast iron pipes.  This is usually not a big problem because the bacteria are contained in the tubercles.   

Water Main Tubercles

Water Main Tubercles

When the water chemistry changes, making the water more corrosive, the tubercles break down, making red water and releasing the accumulated pathogens.  The water leaving the treatment plant is safe, but corrosive conditions in the distribution system release lead from old lead service lines running to houses that have lost their protective coating;  and pathogens are released from tubercules breaking down in the water mains. 

The potable water industry is highly regulated.  The utility itself is mandated to treat and test the water to insure its safety.  This includes testing water from individual taps in the distribution system.  County health departments also regularly test drinking water.  State Health Departments are also equipped to monitor water quality, although normally they rely on reports from the providers.  All this is overseen by EPA under the Safe Drinking Water Act.  The Centers For Disease Control also respond when unusual outbreaks occur. 

This is a lot of regulation and a lot of bureaucracy.  Usually the agencies work well together, as they share the same mission, assuring the water is safe.  The system broke down in Michigan when the state government assumed control of local cities facing a budget crisis.  The emphasis shifted from providing safe water to saving money.  The money savers were not water people and tended to ignore those reporting the unsafe water.  Instead of interagency cooperation, distrust arose.   

Flint is a city in crisis.  It once was a General Motors town, with lots of good paying jobs.  Many of those jobs are gone, the people who could afford to moved away.  Those left are poor and mostly black, with little political influence.  A toxic governmental situation created a toxic water situation.   

A main role of government is to protect the health and safety of the people.  It seems the Michigan state government avoided responsibility in order to save money.  There seems to be a large movement in our country to reduce the size of government.  This cost saving often comes at the expense of infrastructure.  As the roads, bridges, water and sewer systems, schools, police and fire departments decay, the quality of life of the citizens also decays.  All this did not seem to matter in Flint or the rest of Michigan, because the citizens affected tended to be poor and black.

Engineers

Tacoma Narrows Bridge Collapse, 1940. The engineer commited suicide.

Tacoma Narrows Bridge Collapse, 1940. The engineer commited suicide.

Engineers design things.  It may be lines of code for a computer application or the Golden Gate Bridge.  They have been at it for a long time.  Stonehenge, the pyramids, Petra, Roman roads, bridges, and aqueducts; all started as an idea in someone’s mind.  He then added the details to make the thing work.   

The details.  You can conceive of a bridge over a stream, but it has to be assembled, stay in one piece, support the loads going over it, and hold back the flood.  It would be nice if it looks good.  In addition it should not cost more than is necessary.  That is asking a lot, and in most cases the product is good at its job.  Think of it, are the stream banks solid rock or mud?  How deep is it, how do you support the bridge as it is being built?  What material to use?  Stone, wood, steel, iron?  What about the approaches?  How do you get the rainwater or snow off?   

Roman Aqueduct

Roman Aqueduct

There are lots of questions to be asked, and the answers have to be backed up by the numbers.    Stress, load, vibration, weather, wind, soil characteristics, and myriad other details have to be calculated.  Calculations can be avoided only if the thing is so overbuilt that little harm can come to it.  It is hard to do stress analysis with Roman numerals, thus things were overbuilt enough that they are still in service today.   

Currently, overbuilding is not an option due to cost considerations.  The thing has to do its job, last for its design life, be easy to work with, and not cost too much.  I spent thirty years in the water treatment business, and everything in the business has engineering behind it.  Most of the time everything works fine.  But, engineers make mistakes.  Walls collapse, processes don’t work, the power to a pump shorts out, the concrete leaks.  When you turn the new thing on, the software may not work.  All the engineering is critical, because the water has to go down the pipe to the customer, safely. 

For thirty years, I treated water using the engineers products.  Sometimes the product was faulty, but we had to make it work anyway.  The net result of this is that after working with the mistakes for so long, I have a deep, strong, profound anti-engineer bias.  In addition, engineers tend to be serious nerds.  They often are weak in social skills, and have difficulty communicating with others.  Lots of them know they are right, and refuse to listen to input from others who are not engineers.  Mistakes get perpetuated.  I must concede, however, that their stuff mostly works. 

The problems can be minor, like not putting the drains in the low spot to forgetting to account for water hammer in a piping system and pipes separate, flooding things.  A big problem we had to deal with was leaking concrete.  Denver Water has been pouring concrete since about 1900.  A lot of experience is in the specifications provided to the contractor building a new plant.  The contractor failed to follow those specifications and water poured out of the filter walls.  Water also came up through the floor from the channel bringing water into the plant.  It was necessary to take the plant out of service, drain the tanks, clean the walls, and coat them with epoxy.  That epoxy will not last as long as the concrete. 

There was one major exception to my dislike for engineers.  The plant where I worked had elements dating back to the 1920s as well as new construction.  Part of the new project was automating the entire plant.  There are lots of valves, motors, pumps, blowers, and other equipment, all interdependent.   

The software developers worked for months writing the programs to run everything.  There were twelve foot diameter valves, 400 horsepower motors, sensors monitoring every process, and it all had to work.

Water Plant Control Room With My Doppleganger

Water Plant Control Room With My Doppleganger

When we turned the plant on for the first time, it worked.  Everything did what it was supposed to.  This in a three hundred million gallons per day water plant.  In contrast, I started up a 10 MGD plant that just barely worked.  The biggest design flaw was a tank that was supposed to even out the water flow coming from the watershed to the water demand of the plant, which tended to fluctuate.  There were valves at the intake up the mountain, at the tank outlet, and at the plant.  The tank was too small to handle the fluctuations.  The plant was either starved for water or the tank was spilling.  There was software to sense tank level and flows, but it could not keep up.  The tank should have been at least twice the size.   

Don’t get me wrong, the work was challenging, interesting, and sometimes even fun.  There was enough variety to keep boredom at bay, and those engineering mistakes added to the challenge.  What the engineers did right, we just took for granted.