Types of drainage works can at times be like waiting for a bus….

In my many years of being involved with inspection surveys, I can count on one hand the number of times I have been involved in surveying the amazingly engineered brick-egg sewers; low and behold two ARROWFLOW  projects requiring the specialist Crawler stabiliser (helpfully provided by DCR Inspection Systems Ltd) over 2 weeks.

This attachment is mounted to our Minicam CRP140 Crawler; with its electronic raise and auxiliary lighting system; the unique shape of the brick-egg means the Crawler rides atop the lower brickwork (usually the Crawler would travel in the invert of a circular drain or sewer).

Further amazingly (on the second project) the entire (battery powered system) system was mounted on the back of a 4×4, due to the difficult access.

On both projects, some fantastic footage was gained of these amazing feats of engineering.

In the mid-1800s, during the Industrial Revolution, London faced a sanitation crisis known as the “Great Stink.”

Engineer Joseph William Bazalgette took on the monumental task of designing a solution. His innovative sewer network transformed the city’s sanitation infrastructure.

Why the Egg Shape?
The sewers of that era were constructed using bricks. To withstand the weight of the city above and effectively transport waste, Bazalgette needed a robust design.
The egg shape became the solution. When turned upside-down, it closely resembled a V-shaped channel. This unique shape provided several advantages:
·  Strength: The egg shape is inherently strong under compression.
·  Velocity Enhancement: Water velocity increased at low flow rates, aiding in the removal of solids.
·  Efficiency: Unlike circular sewers, the egg shape prevented debris from accumulating.

Bazalgette’s innovative approach not only addressed the immediate crisis but also laid the foundation for modern urban sanitation systems. The egg-shaped sewer design remains a testament to the engineering ingenuity and practicality of the 19th century.