How do ‘infiltration’ fixes impact on home owners?

LETTER

A very interesting article from Gordon Webb on May 12th, re stormwater and sewage treatment options.

To reveal my ignorance, which doesn’t take much, I would like to ask a question. We were told in March that it only took four properties in Kaiti, diverting stormwater into the sewerage system, to “overwhelm” it. This was said to be some 95 percent of the problem. I also understood that properties were being progressively “smoke tested” and investigated to see if they were contributing to the infiltration problem.

What I want to know is, if they are found to have inadequately-protected gully traps or other problems which allow significant (overwhelming) infiltration, what happens? Are the owners then required to make these problems good? And if they are, what sort of time frames or other measures are available?

Ron Taylor

Response from GDC management:

Four properties with downpipes going into the gully trap will overwhelm the sewer in that catchment, which in turn can affect everyone. Just two properties with surface water flowing into their gully traps can do the same.

Ninety-five percent of stormwater getting into the wastewater system is coming from downpipes going into gully traps and also flooding on private property getting into the wastewater system.

Smoke testing is one part of our property inspections — we fill the wastewater system with special smoke, then see where it comes out to identify where there are stormwater connections into the system.

During inspections, our DrainWise team are doing basic sealing of gully traps, but if the gully trap needs raising, renewing or we find problems where a plumber or drainlayer is required, the property owner is responsible to rectify them.

Initially we give them 30 days to fix the issues, but will work with them where they cannot meet that.

A very interesting article from Gordon Webb on May 12th, re stormwater and sewage treatment options.

To reveal my ignorance, which doesn’t take much, I would like to ask a question. We were told in March that it only took four properties in Kaiti, diverting stormwater into the sewerage system, to “overwhelm” it. This was said to be some 95 percent of the problem. I also understood that properties were being progressively “smoke tested” and investigated to see if they were contributing to the infiltration problem.

What I want to know is, if they are found to have inadequately-protected gully traps or other problems which allow significant (overwhelming) infiltration, what happens? Are the owners then required to make these problems good? And if they are, what sort of time frames or other measures are available?

Ron Taylor

Response from GDC management:

Four properties with downpipes going into the gully trap will overwhelm the sewer in that catchment, which in turn can affect everyone. Just two properties with surface water flowing into their gully traps can do the same.

Ninety-five percent of stormwater getting into the wastewater system is coming from downpipes going into gully traps and also flooding on private property getting into the wastewater system.

Smoke testing is one part of our property inspections — we fill the wastewater system with special smoke, then see where it comes out to identify where there are stormwater connections into the system.

During inspections, our DrainWise team are doing basic sealing of gully traps, but if the gully trap needs raising, renewing or we find problems where a plumber or drainlayer is required, the property owner is responsible to rectify them.

Initially we give them 30 days to fix the issues, but will work with them where they cannot meet that.

Your email address will not be published. Comments will display after being approved by a staff member. Comments may be edited for clarity.

Wiki Gerrard - 10 days ago
GDC Management, put a name to your response so we know who is in charge of this area!

Manu Caddie - 10 days ago
Can GDC please point us to the evidence for their claim that 95 percent of infiltration comes from residential downpipes and surface water on private property?
It would be great to see a street-by-street map or chart showing how many properties have been identified as still allowing stormwater to enter the city sewage system and how many have gone beyond the 30 days to fix the issues.
It would also be useful to see a diagram of all the publicly-owned pipes that are cracked and allowing water to infiltrate, and some more information on how many pump stations are still inadequate to handle the normal flow of sewage given the high proportion of discharges that occur outside of any high rainfall event.

Peter Wooding - 10 days ago
Isn't it the case that gully "traps" are indeed traps, i.e. there is an 'S' bend or 'P' bend that traps water and prevents emission of nasty smells from the sewage pipe? If so, how does the 'special smoke' get out?

Poll

  • Voting please wait...
    Your vote has been cast. Reloading page...
    How do you rate National’s election-year Budget?