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Maintaining Venice's Canals

Canal maintenance photo, Venice

ABOVE: Wooden walkways give workers access to foundations along a drained canal. (Venice's buildings sit on foundations of Istrian stone--a type of white marble--which are supported by wooden pilings driven down through the mud to a layer of firm, solid clay.)

Robert Benchley, the humorist who wrote for The New Yorker, once arrived in Venice and sent a cable to his editor that said: "Streets full of water. Please advise."

That pretty much sums up the challenges facing the Venice public-works department. In most cities, repairing the streets is a straightforward process of tearing up the old pavement, grading the surface, and covering a base of dirt, gravel, or crushed rock with a fresh layer of concrete or asphalt. In Venice, however, the streets consist largely of canals--and before the streets can be repaired, somebody has to get rid of the water.

The first step in canal maintenance is to erect one or more cofferdams. These temporary walls seal off the canal from adjacent waterways such as the Grand Canal or the Venetian Lagoon.

Once the cofferdams are in place, the work crew uses pumps to drain the canal. Then comes the hard part: removing the thick, charcoal-grey layer of silt and sludge that may have accumulated over several decades.

At the dredging site, a canal worker uses a small dragline (i.e., a duty-cycle crane) to dig up the sludge and transfer it into a wheeled vehicle with a tilting hopper.

Each time the hopper fills up, the vehicle's driver backs along temporary rails until he reaches a barge. He tips the muck into the barge, then returns to the waiting dragline. This process is repeated hour after hour, day after day, until the canal is ready to be flooded and reopened. Shovels are also used when needed, to clean out whatever the dragline leaves behind.

Two factors make the job more complicated than it might appear at first glance:

  • Ancient pilings. Venice's palaces, churches, and other buildings are supported by thousands of wooden pilings that date back hundreds of years. As long as they're submerged, the pilings won't rot--but when they come in contact with the air, deterioration begins. This requires that exposed wooden pilings be protected during the cleaning of the canal.

  • Public utilities. Today's Venice has water mains, electric power lines, fiber-optic cables, and other utilities, just like any other city. Work crews must be careful to secure exposed utility lines and avoid damaging them while cleaning out the canals.

In The World of Venice, Jan Morris describes the stoical men who clean Venice's canals:

"Far down in the gulley of the empty waterway, beneath the ornate doorways and marble steps of the palaces, you may see the labourers toiling in the sludge....Their bodies, their clothes, their faces are all smeared with the stuff, and if you engage them in conversation their attitude is one of numbed but still mordant resignation."

As the saying goes, "It's a tough job, but someone's got to do it." That's reason enough to drink a toast of thanks to the canal workers of Venice as you sip Prosecco on your next gondola ride.

More photos:

Insula di San Felice

These photos show maintainance work on the San Felice Canal in Cannaregio, just north of the Strada Nova.

The project includes restoration of a bridge, pavement, and foundations in the insula of San Felice, Lotto 1. (Venice's historic center is divided into 40 "insulae," or districts, for integrated public-works projects.)

cofferdam and pumpspipes

The view above shows a cofferdam with pumps on top. The hoses in the drained canal were used to suck up water and discharge it on the other side of the dam (small photo).

public-works barge

A barge sits on the muddy bottom of the drained canal, with a small backhoe being used to excavate muck and sewage sludge, lift pilings into place, etc.

wooden pilings

Traditional wooden pilings are used to replace old pilings that have deteriorated after exposure to air during the renovation project.

Also see:
 Vintage Venice: Canal Maintenance (1999)
Canals of Venice: Canal Maintenance