A More Pleasant Day on the Thames

Cities in the US aren’t the only ones facing problems from undersized sewers and combined sewer overflows. Few of our sewer systems, though—outdated though some are—are quite as antiquated or located in as picturesque a place as the one in London that’s now getting a makeover.

Much of London’s sewer system dates from the 1860s, and it’s not nearly large enough to handle the city’s current population of eight million. Overflow is dumped into the Thames River, and during rainstorms the problem is much worse. As this article notes, overflows used to happen just a few times a year during storms but now occur almost weekly, even in dry weather, with a total of about 40 million tons of untreated sewage a year flowing into the Thames. The Thames is a tidal river, and it can take months for the action of the tides to move the sewage out to sea.

Cities in the US aren’t the only ones facing problems from undersized sewers and combined sewer overflows. Few of our sewer systems, though—outdated though some are—are quite as antiquated or located in as picturesque a place as the one in London that’s now getting a makeover. Much of London’s sewer system dates from the 1860s, and it’s not nearly large enough to handle the city’s current population of eight million. Overflow is dumped into the Thames River, and during rainstorms the problem is much worse. As this article notes, overflows used to happen just a few times a year during storms but now occur almost weekly, even in dry weather, with a total of about 40 million tons of untreated sewage a year flowing into the Thames. The Thames is a tidal river, and it can take months for the action of the tides to move the sewage out to sea. [text_ad] The Thames Tideway Tunnel, just now getting underway and expected to take about seven years to complete at a cost of 4.2 billion British pounds (about US $6.3 billion), will take some of the pressure off the city’s sewer system by channeling much of the raw sewage into a tunnel 65 meters below the riverbed. The tunnel will run for 25 miles along the Thames and eventually deliver the sewage to another tunnel, which will take it to a treatment plant. That treatment plant, incidentally, is undergoing an upgrade of its own to handle the additional volume. When the upgrade is completed in 2021, the Beckton Sewage Treatment Works should be able to treat 60% more wastewater than it does today. That upgrade is expected to cost 190 million British pounds, or about US $288 million. If you are in an area that has combined sewers and occasional or frequent CSOs, has anything similar to this been considered? Are wastewater treatment plant upgrades on the horizon, or are volume reduction measures—including green infrastructure—being used instead?