Extreme Weather Event, Extreme Weather Event, Go Away…

Now, we’re told, we have a new reason to fear climate change: Record rainfalls are straining the capacity of combined-sewer overflow (CSO) systems in Richmond, Lynchburg and Alexandria. In heavy rains, the antiquated systems, which combine stormwater runoff and wastewater, release untreated wastewater into the river.

“We’re on the frontlines dealing with climate change,” Grace LeRose, program manager for the Richmond public utilities, told The Virginia Mercury. “We’re seeing bigger and more frequent storms that are going to tax our system even more.”

In  May and June the city experienced 23 inches of rain, the highest ever recorded. That year, contends the Virginia Mercury, was indicative of a longer-term trend. There was a 33% increase in the number of heavy rainstorms in Virginia, and an 11% increase from the largest storms between 1948 and 2011.

Of course, you can make statistics say anything you want them to, so I thought I’d do some checking.

I consulted the weather.com rainfall database for Richmond. One set of tables displays a Top 10 list of monthly precipitation broken down by month. I arrayed the Top 10 months by year on a spreadsheet. You can see the results in the table above. It is readily apparent that years with months of heavy rainfall occur in clusters. There is a cluster around 1890, another in the mid-1930s, another in the late 1950s, another in the late 1970s, another in the early 2000s, and another in the last few years.

These heavy rainfall clusters do appear to be increasing in frequency, which is consistent with the idea that heavy rainfall events are increasing in intensity — although it’s also consistent with the idea that we’re just having more rainy days as opposed to more heavy rains.

It is also worth noting that the Top 10 month for rainfall in Richmond for all recorded time occurred in July 1945. That month saw 18.87 inches of rain. The next wettest month, Sept. 1999, experienced 16.6 inches, followed by Aug. 2004 with 16.3 inches.

May and June 2018 set a two-month record of 23.67 inches, as the Virginia Mercury points out. But June 2018 had only 13.32 inches.

If you’re cherry picking multiple-month periods for comparison, 1889 saw a four-month wet period with 39.96 inches of precipitation. That was 130 years ago in the pre-Global Warming days.

I also wonder why 1948 was selected as a base year. That year didn’t see a single Top 10 rainfall month. Would Virginia have seen a 33% increase in the number of heavy rainstorms if the base-line had been 1938 or 1958? Is there something magical about looking back 70 years, as opposed to any other number of years?

The question of how best to measure trends in the intensity of rainfall is not one easily resolved. But I don’t know that it matters. The fact is, Richmond, Lynchburg and Alexandria need to overhaul their ancient stormwater/sewer systems today, regardless of how precipitation has increased over the past century or how much it will continue to increase over the next century. CSOs have been prone to overflowing since they were built, and that reality hasn’t changed.

Perhaps a more useful question is to ask how Virginia’s older cities can cope with extreme weather events. Is it a better investment of scarce resources to build water treatment facilities with bigger capacity or to “soften” the city’s infrastructure of roofs, sidewalks, roads and streets to make them capable of filtering, storing, and slowing the release of rainwater? Richmond went through a flurry of building “rain gardens” a few years back. The rain gardens were looking pretty forlorn and neglected the last time I looked.

It’s probably easier (if not more cost effective) just to apply for state and federal grants, issue some bonds, and engineer a massive hard infrastructure project. That’s what Richmond is doing. The city is in the process of upgrading its wastewater plant, adding 65 million gallons per day over its existing 75 million gallons per day. I hope it’s worth the investment.

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18 responses to “Extreme Weather Event, Extreme Weather Event, Go Away…

  1. Careful….somebody might figure out that water vapor is far more important in explaining any greenhouse gas effect than CO2. But even the truest of true believers cannot designate water vapor as “pollution.” Well, on second thought, they might try…..

    You are on to a key point – the real issue is to be ready for that long-overdue major hurricane event in VA, and those explain most of those heavy rainfall records in the past you cite. I don’t need to accept the Climate Chicken Little hypothesis to expect a big hurricane and know we aren’t ready in most places.

  2. https://youtu.be/mqejXs7XgsU

    The Wattsupwiththat website is such fun. I know, Heartland Institute, so I’m supposed to know all those four guys are hopelessly corrupted….

  3. The clusters of heavy rainfall had clusters of drought years in between too. Was 1948 selected as a starting point because the 1930-32 drought was one of the most severe droughts recorded in Virginia? Other drought periods were 1938-42, 1962-71, 1980-82, according to a post at https://www.loudounhistory.org/history/drought-1930-history/ drought.gov has a graph for Drought in Virginia from 2000-2019 from the U.S. Drought Monitor that started in 2000. It says Va’s longest drought was 103 weeks from May 1, 2007-April 14, 2009, with the greatest intensity in 2002. Va started a drought monitoring task force because of the 2002 drought. That monitoring has been discontinued because of all the precipitation. What would have made more sense is renaming it Precipitation Monitoring and tracking the amount of precipitation without all the stream monitoring, but that would mean we’d have to look at the whole picture and not alarmist snapshots of selected data. It’d be interesting to see the drought chart at https://www.drought.gov/drought/states/virginia overlaid on the precipitation chart in the post above.

    • I think the 1948 start date for a lot of meteorologic data has more to do with the significant expansion of Weather Bureau support for civil aviation after WWII, as a part of which, record-keeping was increased widely. There are of course exceptions where the data goes way back.

  4. Here we go: Palmer Drought Severity Index for Virginia by NOAA showing precipitation cycles from 1895 to 2019. https://www.ncdc.noaa.gov/cag/statewide/time-series/44/pdsi/all/0/1895-2019

  5. Heads, I win. Tails, you lose. Warm weather is caused by climate change. Cold weather is caused by climate change. Dry weather is caused by climate change. Wet weather is caused by climate change. More hurricanes is caused by climate change. Fewer hurricanes are caused by climate change. More taxpayer dollars are caused by climate change.

    Researchers have discovered remains of a homo sapiens-related person in the Philippines that was at least 50,000 years old. Several scientists said this discovery will force us to rethink much of what we know about human existence. We are constantly learning in every field of science except “climate science.” We already know everything there is to know in that field. And, of course, unlike other sciences, where people are caught falsifying their research, no one in climate science does this.

    https://www.nytimes.com/2015/06/01/opinion/scientists-who-cheat.html

  6. Climate change is real. The polar ice is melting. The sea level is rising. Dominion is still burning coal.

    C’mon boys … time to stop denying and start looking for solutions. Virginia, the US and the world may not be able to move as fast as our liberal friends would like but we need to get started.

    • I don’t claim climate change is not real. But I do claim some data are being manipulated; falsification of data and results are ignored; and no one looks beyond the shibboleth – Climate Change – for every conceivable WEATHER event.

      I will take things a lot more seriously when we start taxing those property owners on floodable land for at least some of the costs for reducing emissions and taking remedial actions. Talk about a transfer of wealth from those who have less to those who have more. Who has more money? Those whose property has water frontage or those who do not?

  7. I HAVE noticed in the last few years what seems to be a marked increase in smaller bridges and culverts being washed away and then VDOT taking weeks/months to fix them.

    If there actually is an increase in culvert failures due to rain events, that might mean higher intensity rainfall as opposed to more rain overall – but spread out more evenly.

    We’ve always had bigger watershed floods over the decades.

    Richmond has a massive flood wall that was put in after one of those floods but I cannot recall the last time it was sealed to ward off flooding.

  8. Climate change is.

    Just stop it there, because the changes have been going on since the BoT (beginning of time….) Is human activity having an impact? Sure. How do we fix that? Three billion fewer humans (ouch)…..Does that mean we don’t worry about coal pollution, etc? Of course not, stupid to burn coal with so many cleaner alternatives. But one of those is natural gas and the other is nuclear, driving the Left to distraction….

    Larry, look up the effect of the remnant of tropical storm Gaston on downtown Richmond and that will explain why they are very slow to close those gates now. Idiots trapped the water on the wrong side and flooded everything downtown….

  9. Larry: Pipe failures occur during rain events. The cause is VDOT’s long term failure to maintain its infrastructure, do required annual inspections, and plan replacements for failing structures before they washout or collapse. Preventive maintenance is a VDOT oxymoron.

  10. For me, the most pressing question arising from the Virginia Mercury article is not the one of record rainfalls and their relationship to climate change, but what is Richmond doing about its combined sewer overflow system. And, I am confused by what I read.

    Richmond, Lynchburg, and Alexandria have old combined sewer overflow systems. In these systems, storm water flows into the same pipes that take wastewater to the sewage plant for treatment. That leads to several problems. First, it is wasteful and inefficient. They are using a lot of expensive chemicals and other treatment processes to treat water that does not need treatment. Second, when there are heavy rains, the sewage treatment plant becomes overloaded with the flow and dumps raw sewage into the nearby river (the James for Richmond and Lynchburg).

    The answer is to separate the systems that collect the stormwater and the wastewater. The stormwater goes to the river; the wastewater goes to the sewage treatment plant. That is an expensive proposition. For several years, the localities have been working to separate the systems. The state has provided significant financial assistance. I have not taken the time to go through all the relevant Appropriation Acts to calculate the total amount, but, for example, the 2013 Appropriation Act provided $75 million–$30 million for Lynchburg and $45 million for Richmond—to help reconstruct the CSO systems. After a couple of false starts, Alexandria got some help, $25 million, from the 2019 session.

    Jim asked which is the better approach: invest a lot to increase treatment capacity or soften the city’s infrastructure in order to filter, store, and slow stormwater. The answer is that both need to be done. Once the stormwater is separated from the sewer flow, it cannot be ignored. Unimpeded, surges of stormwater can result in flooding, silt deposits, and washing of pollutants from streets and yards into rivers. Therefore, reducing a city’s impermeable surface area is important, but a separate issue from that of treatment capacity.

    Here is where my confusion sets in. In a 2017 RTD article linked to in the Virginia Mercury article, there is this statement: “Though all of the separation of lines that will take place is complete, the city is still working to build capacity to process more wastewater during heavy rain.” The Virginia Mercury reports that Richmond is working to almost double its wastewater treatment capacity. These statements imply that not all of the stormwater collection system has been separated from the sewage collection system and there is no plan for complete separation. Thus, some stormwater will continue to be sent to the sewage treatment plant, with resulting overflows, although fewer than in the past. These implications lead to the following questions:

    1. Is it a fact that not all stormwater lines will be separated from the sewer system?
    2. If this is true, why?
    3. If this is true, what percentage of the stormwater system will be connected to the sewage system?
    4. If at least some of the stormwater is being separated from the sewage system, why is it necessary to double the capacity of the sewage treatment plant?

    • Excellent questions. Better than the questions I posed.

    • In answer to your questions, Dick, I don’t think ANY of the three cities you name or the many smaller jurisdictions with 19th century sewer infrastructure in some portions of town are EVER going to be 100% separated. It’s horribly expensive to dig every one of those streets up to lay (and connect all the street drains and house downspouts to) parallel storm sewer pipes alongside the old sanitary sewer lines right up to every house and every business on the street. And even if you do, there’s the problem of separation at the source. Arlington, for example, has separate systems but still struggles with the storm runoff from older houses whose roofs (and some driveways) dump directly into the sanitary sewage pipe serving the house. In every case there’s a point of diminishing returns. I don’t know how those criteria are evaluated but somebody reading this may know more about it.

  11. Thanks Dick – and yes… good questions not delved into enough so that we can be better informed.

    One caveat – Storm water while not sewage is still a nasty brew of pollutants to include stuff like animal poop, fertilizers, weed killers, anti-freeze and oil, etc. Just “separating” it and then letting it flow into the waterways is also a problem.

    In fact, there is debate that at least some – already separated storm runoff that is captured in modern day storm ponds – needs to be treated before released. I’d suggest for anyone who doubts this to take the time to go inspect a storm pond that has been around for 5-10 years and you’ll see a pile of floating debris that typically has to be removed but what you don’t see that is also there from the same runoff is fecal matter, antifreeze, oil, etc.. that more often than not is not treated and just goes directly into the receiving waters when large rain events occur and the storm pond overflows.

    • Larry, I realized that this subject is more complex than I was setting it out. I suspect that some of the problems with storm water that you raised may be the explanation for the city’s approach. I’m interested enough that I may follow up with the city. If I do, I will let BR readers know what I find out.

  12. Fairfax County requires Tysons developers to retain the first inch of rain on the property through infiltration, evapotranspiration and/or reuse.

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