Sanitation

The water goes first. Flushing takes water somebody has to spare, and after a major earthquake nobody has water to spare. Why the water stops, and for how long, is set out there.

A house has a garden, a bucket, and somewhere to dig. A unit on the twentieth floor has a bathroom, and when the water stops the bathroom stops with it.

PreparedBC tells residents to store four litres per person per day, for drinking and sanitation. [2] Vancouver’s Rain City Strategy sets that against ordinary use: it “falls short of normal daily water use by more than 300 L per day, and provides the bare minimum for drinking and hygiene”. [3]

Four litres covers drinking and washing. There is nothing in it for a toilet.

“Disruption to water and wastewater systems are expected for many months following the event.” [1] That is the Provincial Earthquake Immediate Response Strategy, the province’s own plan, and wastewater is named in it.

The province wrote it for its shallow crustal M7 planning scenario, and has published nothing equivalent for the megathrust. It covers the whole affected region, with no municipality broken out. Water and wastewater are merged into one sentence, so it does not say whether one returns before the other, and it does not separate the treatment plants from the pipes.

The province publishes shorter intervals for drinking water. They measure how long it takes to truck bulk water to people, which is a different question from when a sewer works again, and they are set out with water.

Possible is the province’s word, not likely and not expected.

Inadequate disposal is the step between a collection service that has stopped and a risk to health, and it is the one link in the chain a household can act on.

Waste collection is the garbage as well as the sewage, and a garbage truck needs roads and fuel like every other repair in this section. Shelters are where the province names the risk, because that is where people are gathered together.

The 2011 earthquake in Christchurch, New Zealand, shows what a failed collection system does to ordinary life. Chemical toilets were provided for about 30,000 residents and 1,141 portaloos were delivered. [4] Temporary toilets stayed in use for weeks. [5] Sewer repairs were projected to take more than a couple of years, [4] and a later council estimate put full network restoration at up to 30 years. [6] The last two figures are about rebuilding a network, not about how long anyone used a portaloo. All of them describe Christchurch, and none of them says anything about how long Richmond’s or Delta’s sewers would be out.

Metro Vancouver lists what it has built or designed to a post-disaster standard, which means a structure the building code expects to keep working after the earthquake. The list includes the Annacis Island plant’s Stage 5 expansion, the North Shore secondary treatment plant, the new Hollyburn pump station, and the Sperling and Sapperton pump stations, which were under construction with seismic upgrades. [7]

The work goes one plant and one pump station at a time. A pump station needs power to run, too. Sewage reaches those plants through pipes, and the sewers are the part whose assessed condition is not public.

Annacis Island serves about 1.25 million people across 14 municipalities, and its remaining stage-gate approvals run from 2027 to 2030, with all components anticipated by 2035. [8] Iona Island was built in 1963, serves about 750,000 people, and is being rebuilt for secondary treatment with seismic and flood-resilient design for its position on the delta. [9]

The City of Vancouver’s Engineering Design Manual has a section headed Seismic Design Standards inside its sanitary sewer part, with a parallel one for storm drainage. [11] A designer choosing pipe material and replacement strategy has to work from a risk assessment: how important the pipe is, how susceptible the soil is to shaking, and its potential for permanent ground deformation, which is ground that moves and does not move back. [11] The strategies are named too, among them routing mains outside liquefaction zones, where saturated soil loses its strength and behaves like a liquid while the ground shakes. [11]

“Minimize seismic risk to sewage and drainage services” is objective 3.4 of the City’s Healthy Waters Plan. [12] Progress against it is measured on a rating scale of 1 to 5 by expert judgement. [12]

Nothing published says how the network already under the streets would perform, and nothing says the replacement pipe performs better or worse than what it replaces. Nobody has measured it.