Interview on soil issues surrounding Richmond tunnel gets cut off
The following is a transcript of an interview that was cut short between CTV's Daryl Newcombe and a consultant with the City of London on the issue of sandy soil and groundwater at the site of the proposed Richmond Street BRT tunnel.
A geotechnical report confirms sandy soil conditions, and groundwater at a depth at the tunnel site that could cause problems for construction.
The interview was abruptly broken off by the City's new Manager of Communications for Rapid Transit, Nathan MacDonald, when questions turned to whether removing ground water would trigger land seettlement beneath adjacent buildings.
You can read the full exhange belowor click on the video.
Daryl Newcombe speaking with Eric Peissel, consultant for the City of London with WSP:
NEWCOMBE: Talk to me first of all.. the geotechnical report was received and posted recently. Its very technical (lives up to the name geo"technical"). How should the lay person or average Londoner interpret that report? In simplified terms what are the actual findings?
PEISSEL: The actual finding of the report, it actually demonstrates there are two feasible techniques to build the tunnel as currently recommended as part of this transportation master plan.
NEWCOMBE: What kind of challenges does the sand in the soil, I know there's sand and then sandy gravel below it, what kind of specific challenges might those create if any?
PEISSEL: The report itself makes clear recommendations on exactly how to handle those sorts of soils, including the construction techniques including the mitigation measures. So that is exactly why we have this sort of report, is to inform this sort of decision making.
NEWCOMBE: Talk to me about the groundwater level too. Would you consider it high, average, what we expect in downtown London given our past experience?
PEISSEL:As the report noted it's in fact very variable and it gives exactly how to handle the situations with that, including the type of dewatering required and the mitigation measures and as the report states its very similar to the conditions that is encountered in that part of London.
NEWCOMBE: Speak to me because, a lot of construction projects specifically high rises, that has limited how deep they can go with their underground parking, it is often at planning committee meetings a real significant factor. How does this tunnel deal with that ground water level which in some areas could be at tunnel depth?
PEISSEL: Well, I don't really want to get into the specific details but in fact in the geotechnical report it indicates the depths, this is a shallow tunnel and the mitigation measures are clearly outlined.
NEWCOMBE: Talk to me about settlement of adjacent properties if we do dewater that area?
PEISSEL: Well, once again proper mitigation measures, tie backs and everything, are within the report itself, I don't want to get in the technicalities of all of this here.
NEWCOMBE: What happens if we dewater, we can't dewater a specific area, we dewater an area larger than the actual tunnel, what....
PEISSEL: We, we really don't want to get into all of the, the technical aspects at this point in terms of this interview. All of this will be examined in detail as we move forward in the project.
NEWCOMBE: Should business owners alongside the tunnel or property owners alongside where the tunnel intends to be going, should they have concerns about settlement? Or are those
PEISSEL: That will all be addressed in the engineering phase so as I said I don't want to be speculating on any of that.
NEWCOMBE: Is there a compromise to buildings if settlement happens? What, what does settlement do to a building?
PEISSEL: Once, once again its exactly the same answer I've been giving you before, you are kind of asking the same question over again, so.
At this point Nathan MacDonald steps in.
MACDONALD: Alright we're good.
PEISSEL: We're good?
MACDONALD: Okay, done.
NEWCOMBE: So you don't want to answer any more questions?
MACDONALD: He's been very clear, the fact that it is feasible to build. And that's all we have to say about it at this time.