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Subsidence

Subsidence

FromLet's Know Things


Subsidence

FromLet's Know Things

ratings:
Length:
20 minutes
Released:
Jan 9, 2024
Format:
Podcast episode

Description

This week we talk about the raising of Chicago, Jakarta, and sea level rise.We also discuss groundwater, flooding, and insurance.Recommended Book: Once Upon a Tome by Oliver DarkshireTranscriptIn the mid-19th century, the city of Chicago, its many sidewalks and buildings and other infrastructure, were hoisted using jackscrews, which are kind of like heavy-duty versions of the jacks you might use to lift your car to replace a tire.The impetus for this undertaking, which was substantial and paid for with a combination of city and private funds, was Chicago's persistent drainage issues: the city was located at about the same altitude as neighboring Lake Michigan, and the ground upon which it was constructed was consequently pretty swampy to begin with, but became even more so as all those sidewalks and buildings and other human-made environmental objects were installed, putting downward pressure on that swampy soil, which led to widespread and persistent pools of standing water throughout the city.All this standing water led to the spread of diseases like dysentery and typhoid fever—the sorts of issues that tend to arise when there's opportunity for pathogenic beasties to hang out and spread and come into contact with drinking water sources, not to mention essentially every surface in a city, and in 1854 there was an outbreak of cholera—which is also caused by bacteria getting into peoples' bodies, usually from infected water sources—that killed about 6% of Chicago's total population.So this was an area that was already prone to what's called subsidence—the sinking of land that can be both natural and sparked or amplified by human activity in various ways—and Chicago's development into a city sped up that process, causing it to sink even further, quite rapidly, and that led to a collection of mostly but not exclusively water-related issues, which at this moment in history, the mid-19th century, meant a lot of disease-spread due to insufficient water sanitation efforts and infrastructure, and a very hit-or-miss understanding of the mechanisms of the diseases that were carried by that insufficiently treated water.The first brick building to be hoisted in this way was elevated in January of 1858 and required about 200 jackscrews to lift it six feet and 2 inches higher than its previous altitude, and that kicked-off a period of remarkably rapid and successful elevations throughout the city, including all sorts of huge, heavy, at times quite wide and cumbersome buildings of all heights and material composition, installing elements of the city's new sewage systems around the existing buildings, then covering all that up with soil, pouring or reinstalling roads and sidewalks atop that soil at the new height, and then raising all the buildings, filling the space beneath them with soil as they were slowly cranked up to that new baseline.This wasn't a straightforward effort, and there were several false-starts, initial problems that had to be solved, and quite a few pieces of the old city that either couldn't be elevated, and thus had to be buried and rebuilt, or that were moved to new locations, placed on rollers and shifted to areas, mostly on the outskirts of the city, which kept them aloft without having to raise them using the jackscrew method.Interestingly, some of the elevated buildings, like the Tremont House hotel, continued to function even as they were raised; guests continued to frequent the hotel, and some of them apparently didn't even realize it was in the process of being elevated while they were staying there.This process was largely completed in the 1960s, and much of the city, as it existed at the time, was raised by 4 and 14 feet—and that provided space for the new sewage system that would help with all those water and water-borne illness issues, while also establishing a new baseline altitude for future developments, which would be able to use that same sewer system while also being lifted up high enough that flooding
Released:
Jan 9, 2024
Format:
Podcast episode

Titles in the series (100)

Author and analytic journalist Colin Wright puts the news into context.