Tallinna Vesi: Wastewater overhaul to safeguard against future flooding

Flooding in Tallinn.
Flooding in Tallinn. Source: Siim Lõvi /ERR

Long-running sewage and wastewater reconstruction in Tallinn should, once finished, help in avoiding further flooding of the capital's streets such as that seen on Tuesday night, Tallinna Vesi says.

Tallinna Vesi is a private sector firm which supplies not only Tallinn's drinking water, but is also responsible for sewage and wastewater disposal. As such, dealing with storm water run-off falls under its remit.

The second half of Tuesday this week saw over 80 percent of the usual, expected average rainfall for the whole of July arrive in one go, leading to extensive flooding in the capital, most notably along the relatively newly-built Reidi tee.

Tallinna Vesi spokesperson Marta-Magdaleen Kuningas told ERR that: "These types of situations can be alleviated in the future by restructuring the rainwater sewerage system in Central and North Tallinn into a separate flow system."

"These activities are also provided for in the next 12-year Tallinn public water supply and sewerage development plan, prepared this year in cooperation with the City of Tallinn," Kuningas went on.

This plan takes in the ongoing reconstruction of Jõe and Pronksi, in central Tallinn, the location of one part of the planned new split-flow rainwater system.

 "In the future, this will take the burden off collector No. 1 (Lasnamäe-Kesklinn-Pirita), controlled by the sewage treatment plant," Kuningas went on.

Currently, surface run-off in Tallinn mainly drains away either via common or separate wastewater outflows, which then reach the treatment plant .

A split-flow system would direct rainwater is directed directly into the sea, generally without treatment. 

Commenting on the flooding on the relatively recently completed Reidi road in Tallinn, Kuningas referred to the large volume of water that fell from around 1 p.m. to 3 a.m., Tuesday to Wednesday this week.

"Following the construction of the new rainwater collector in the Reidi tee aera, floods will have fallen significantly, but yesterday's volume of precipitation was truly exceptional," she said.

The sheer inundation Tuesday to Wednesday night meant that there was often nowhere for rainwater to go, hence the floods.

At the same time, Kuningas said, new sewage pipelines of too large a dimension would not fit in the capital's narrow streets and would not be effective either, requiring constant maintenance to keep going, she said.

Tallinna Vesi has, Kuningas added, been working on a split-system over a period of many years.

"The process time-consuming, but it yields positive results and means the number of flooding incidents will fall down the years."

Some other solutions already in use include drainage ponds and beds and special road surfaces which encourage surface run-off from the streets on to nearby patches of grass or earth, the spokesperson added.

Tallinn as by far the largest city in Estonia reported more severe repercussions from Tuesday's downpour than other settlements, even just outside the capital.

Most of Estonia's regional water supply is municipality-run, though there are some smaller private outfits in existence.

In more rural areas, obtaining drinking water, via use of a pump, from a well, is quite common.


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Editor: Andrew Whyte, Mait Ots

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