Utility systems have fascinated me my entire career. Water, wastewater, stormwater drainage, electric, gas. Roadways are usually not referred to as a utility system, but they actually are part of utility family as I view it. All of them are expensive investments. Ginormous to use a word from my grandchildren’s vocabulary. A huge part of these assets are visible. However, the majority are not. They are underground. Even a roadway is thought to be visible, but it is the base material and conditions beneath the surface that is where the problems usually start.
The Water System.
There are two numbers I have been urging cities to place in the primary financial disclosure documents, mainly the Comprehensive Annual Financial Reports (CAFRs), for many years. The first is the Water Loss & Unaccounted For. This sounds like an awkward label and bad grammar. It is actually an officially recognized description by the American Water Works Association.
The “Loss” part is mainly referring to leaks in the water system. You can often pinpoint a leak with clarity. That is when the water is spewing 50 feet high from a breakage, and the news cameras are out for the photo-op. Or when water is leaking underground and creating rivulets that call your attention to a leak. Like a sprinkler system leaking, although usually larger. However, there are many leaks where the hole is on the bottom of the big water line creating a cavity that may not be detected until the street cracks open to reveal a huge cavern has been created over time and has swallowed a car.
The “Unaccounted For” includes many of the gallons of true lost water. But it is a bigger and more complicated issues. Water is brought into a city in huge transmission lines. The entry point is usually metered. However, the meter must be checked for accuracy and re-calibrated at times. McKinney receives about 25.3 million gallons every single day from the North Texas Municipal Water District to serve 51,636 connections. Those are published numbers available online.
Interestingly, the numbers not published are the ones most important to me – and they should be to you. The average per water customer use per day is 490 gpd. To put it in context, ten years ago that metric was 673 gpd. What can we make of it? Conservation? Inaccurate data? Actually, to be totally fair, we just start with that number, fill in the middle years and examine more closely to see the trends. There are many significant weather factors that can wreck those numbers. The water intake meters from NTMWD are read on the first of the month. The consumer meters are read on a cycle throughout the month, so one has to do a computation to get a good estimate of the water metered to the customer that matches the calendar month.
But the missing number is this: what is the Water Loss & Unaccounted For number?
It does not get published annually and for all to see. It is the most revealing number I can think of to grasp an understanding of the condition of the water distribution system. A newspaper account reports the City had a 28% loss in 2014. Are you kidding me? That would be about 2.5 billion gallons! That’s 12,500 elevated storage tanks the size on Virginia near Hardin!
Hold on. Let’s try to get a perspective. What was that WL&UF number over the last 10 years. Hmm! We don’t know. If it is calculated, it is not published in a report I can find online. It is generally believed that about the best that value can get for a city is about 7%. The paper reports 12% is the norm.
It depends on the age of the system, soil conditions and, of course, weather conditions. There can be unmetered water for street medians or even ballfields. In most cases, cities have either metered or have good estimating measures for those. Tell me the size of the meter and the water pressure, and I can tell you how many gallons per minute can go through the line. All I need is the hours the sprinklers have been on for the month.
There can be theft. However, I feel quite confident that this 2.5 billion gallons is not about theft. I do know that residential water meters tend to start under-reading when they get into the range of 7-10 years of age or about a million gallons. It would be nice to know the average age of the 51,636 connections. Let’s usage 12 years as an average to be generous. We would be fairly safe in expecting that about 4,300 meters per year are being replaced if we are keeping up with the necessary life-cycle plan. Is that happening?
In fact, what is the average age of 826 miles of water lines, 628 miles of sewer lines and 430 miles of storm drainage system? Most of those items last about 20-35 years, but do the math. Gee, “brand new” Stonebridge, at least the early sections of the 6,250 acres, is in that zone now. Infrastructure deterioration is an exponential curve, not a straight line.
Wastewater.
The key metric here is Inflow & Infiltration. (I&I). Inflow is when manhole covers have popped off from water just pouring into the sewer system. Infiltration is when roots and breaks underground are causing underground water to seep in. Together they make up millions of gallons (gee, I hope it is not billions of gallons!) that McKinney pays to treat that unnecessary part of rainwater. Same same factors discussed apply as with water except wastewater is not metered for all but the largest commercial customers as well as the city as a whole. It is an estimate based on the water usage. But even with estimates, it can be calculated with a fair degree of accuracy.
What we can guess is that the condition of the sewer system tends to be worse than the water system due to the content of the flow and the fact the flow is by gravity more than a forced flow under pressure. Roots don’t generally get into a pressurized water line and could get detected if they did. There are 51,636 checkers of the water quality as we turn on our faucets every day. Not so with the sewer system.
Conclusion.
I’m going to save roadways and other components of the infrastructure for future blogs.
I have a real problem with cities not showing these key statistics on a 10-year trend:
Water Loss & Unaccounted For.
Wastewater Inflow & Infiltration.
Average Age of Roadway Street Miles; Water and Sewer miles; and Water Meters.
In the name of transparency, I challenge the City of McKinney to publish these vital statistics in their next CAFR. Also, the CAFR will have 10-years of annual data. The Web site should show these calculations on a monthly basis as well as the linear feet of replacement or breakage repairs.
No business would operate a $Billion enterprise and not know these numbers and the trends. LFM
Let's Talk About It, Lewis! 