Private Pumping Station Problems
Comments
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But adoption will be Thames Water? If so, what are you working to with regard specification and design?
The pumping station is a standard bit of kit, a Vortex packaged system. We are bypassing it altogether and connecting straight to the gravity sewer. A heck of a lot of groundworks involved. We of course already connect to the same sewer anyway - albeit via the pumping station at the minute.
There are mixed professional views on whether it is over capacity or not and how many properties it could serve - but I expect it is roughly twice as big as it needed to be from my maths and quotations on similar systems0 -
I don't understand the conclusion arrived at by Environmental Health, nor the solution currently being implemented. You say "In short the pumping station does not pump out frequently enough in order operate efficiently, causing a build-up of odors affecting neighboring properties." If this is a pure pumping station, rather than a packaged treatment plant, then the obvious solution to the infrequent pumping is either to alter the control system so the pumps cycle on a more frequent basis, or reduce the capacity of the wet well. It shouldn't be costing multiple-thousands of pounds to fix the problem (which may come up as an issue if any legal action is taken).
The effect of the wet well being over capacity would be the foul discharge from your properties would sit in the wet well for a period of time before being pumped out. do you know how long this is? Unless you and your neighbours have some serious health issues, the far greater percentage of the content of the wet well would be 'clean' water (i.e. drainage from baths, showers, washing machine etc) the soap and detergent content of which typically has a 'nice' smell. I would expect the contents of the wet well for up to four or five days to have very little unpleasant odour. It is also strange that the neighbours are aware of the problem and not you.
Pumping stations are normally designed to either operate on a timed basis, or a level basis. The timed approach means the pump(s) are switched on after a specific amount of time after the last cycle - most likely to be used where a relatively large catchment produces a reasonably steady flow. Level switched pumping simply means the pumps start when a specific trigger level is reached. Your description makes it sound like the latter is being used and the claimed problem is it is taking too long for the trigger level to be reached.
In terms of solutions, the easiest (and I assume not feasible) is to adjust the trigger level so the pumps operate when a smaller volume of water has collected. The second best approach is to modify the control system so the pumps are operated after a certain period of time even if the trigger level hasn't been reached. If the manufacturer cannot or will not supply such modifications, then a competent electrician should be able to make the necessary changes, but this would impact on the manufacturer's support (if any).
The third option, possibly the one of least cost, is to reduce the capacity of the wet well. There are a variety of ways of doing this, but the simplest would be to (carefully!) lower some concrete blocks into the wet well. This in principle is no different to the toilet flush volume reducers which replace some of the space in the cistern/wet well with a semi-permanent object.
But the thing that interests me is the comment about the existing property's waste traps. That indicates the source of the smell is via the connecting sewer, not above ground. Even poor quality waste traps should still prevent smells coming back up into the house from the sewer.
The thing I would have looked into is whether the problem is the pumping station causing a rush of air through the rising main (the pipe connecting the pumps to the gravity sewer) and that this air is not being vented properly and is causing the water seal in the neighbour's traps to be broken allowing the smell out. This should be extremely unlikely as the neighbour's drainage system should have at least some external ventilation preventing an air pressure build up - but I've seen many strange drainage problems and assuming things have been done correctly is never a good idea. If this was the actual cause of the problem then the simple solution would have been to add a vent pipe to the rising main discharge manhole, which at most shouldn't have cost more than a few hundred pounds.
It sounds like it is too late to stop the work to replace the pumping station with a gravity connection. But if it was me I would want a lot more detail about the problem and why I was being expected to carry out expensive work to solve what should have been a relatively simple issue. Presumably a pumping station was originally installed because it was cheaper to do that with a shallow rising main, rather than laying a gravity pipe in deep excavations?"In the future, everyone will be rich for 15 minutes"0 -
I don't understand the conclusion arrived at by Environmental Health, nor the solution currently being implemented. You say "In short the pumping station does not pump out frequently enough in order operate efficiently, causing a build-up of odors affecting neighboring properties." If this is a pure pumping station, rather than a packaged treatment plant, then the obvious solution to the infrequent pumping is either to alter the control system so the pumps cycle on a more frequent basis, or reduce the capacity of the wet well. It shouldn't be costing multiple-thousands of pounds to fix the problem (which may come up as an issue if any legal action is taken).
The effect of the wet well being over capacity would be the foul discharge from your properties would sit in the wet well for a period of time before being pumped out. do you know how long this is? Unless you and your neighbours have some serious health issues, the far greater percentage of the content of the wet well would be 'clean' water (i.e. drainage from baths, showers, washing machine etc) the soap and detergent content of which typically has a 'nice' smell. I would expect the contents of the wet well for up to four or five days to have very little unpleasant odour. It is also strange that the neighbours are aware of the problem and not you.
Pumping stations are normally designed to either operate on a timed basis, or a level basis. The timed approach means the pump(s) are switched on after a specific amount of time after the last cycle - most likely to be used where a relatively large catchment produces a reasonably steady flow. Level switched pumping simply means the pumps start when a specific trigger level is reached. Your description makes it sound like the latter is being used and the claimed problem is it is taking too long for the trigger level to be reached.
In terms of solutions, the easiest (and I assume not feasible) is to adjust the trigger level so the pumps operate when a smaller volume of water has collected. The second best approach is to modify the control system so the pumps are operated after a certain period of time even if the trigger level hasn't been reached. If the manufacturer cannot or will not supply such modifications, then a competent electrician should be able to make the necessary changes, but this would impact on the manufacturer's support (if any).
The third option, possibly the one of least cost, is to reduce the capacity of the wet well. There are a variety of ways of doing this, but the simplest would be to (carefully!) lower some concrete blocks into the wet well. This in principle is no different to the toilet flush volume reducers which replace some of the space in the cistern/wet well with a semi-permanent object.
But the thing that interests me is the comment about the existing property's waste traps. That indicates the source of the smell is via the connecting sewer, not above ground. Even poor quality waste traps should still prevent smells coming back up into the house from the sewer.
The thing I would have looked into is whether the problem is the pumping station causing a rush of air through the rising main (the pipe connecting the pumps to the gravity sewer) and that this air is not being vented properly and is causing the water seal in the neighbour's traps to be broken allowing the smell out. This should be extremely unlikely as the neighbour's drainage system should have at least some external ventilation preventing an air pressure build up - but I've seen many strange drainage problems and assuming things have been done correctly is never a good idea. If this was the actual cause of the problem then the simple solution would have been to add a vent pipe to the rising main discharge manhole, which at most shouldn't have cost more than a few hundred pounds.
It sounds like it is too late to stop the work to replace the pumping station with a gravity connection. But if it was me I would want a lot more detail about the problem and why I was being expected to carry out expensive work to solve what should have been a relatively simple issue. Presumably a pumping station was originally installed because it was cheaper to do that with a shallow rising main, rather than laying a gravity pipe in deep excavations?
You make so many good points and correct assumptions it is hard to know where to start, I will try bullet pointing some answers.
1. Yes the current system operates on a float level and they are set as low as they can be. The report claims that septicity occurs after 6 hours and the pumps are only operating twice in a 24 hour period.
2. The system is not vented - much to our surprise.
3. There are apparent 'Flat spits' where sediment accumulates and dangerous gases build up which are disrupted when pumps are activated.
4. We toyed with the idea of reducing capacity with concrete but this was still a reasonably expensive option and there were no guarantees it would solve the problem - what's more we would still have a pumping station and all the ongoing maintenance costs and no idea of any future adoption terms.
5. The report was actually very comprehensive and carried out via an external firm RWC Plc . It detailed numerous options many covered by yourself above, but ultimately the best solution was deemed to be to connect to gravity if possible.
6. The other properties have also had some work carried out at their own cost. Not all properties were affected in the first place indicating sub standard drainage seals and internal plumbing although the main properties affected were nearest where the pumping station joined the gravity.0 -
As an aside I would also add that what with possession being 9/10ths of the law, our names on the management company and the urgency to fix immediately (as we have done twice when capacitors have failed) that it is extremely difficult to pass the buck after the event. Add to this the 5 years since construction and the response very much seems to be that of 'your problem'0
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Taking your points in a slightly different order... yes a pumping station does have ongoing maintenance and running costs and a gravity solution is almost always* the preferable option if economically and practically viable. (*the main exception being where the discharge sewer is subject to flooding)
I don't have all the facts and it isn't an area I'd claim expertise in, but 6 hours to septicity does sound very fast. There are other solutions to septicity, and one is to add an aeration/circulating pump which as you already have a power supply in the pumping station is not usually difficult or expensive.
I guess it is 'flat spots' - either in the rising main or in the wet well. That could be a problem if the rising main is excessively large, but again in either case the problem could be solved relatively cheaply.
Reducing the capacity of the wet well with concrete shouldn't be that expensive, concrete is a relatively cheap material after all.
At the end of the day, if you are happy with a solution that means a reduced maintenance cost gravity connection then you have a fair outcome. But I would be very wary of trying to recover the costs of the work off anybody else involved with the pumping station design and construction, including the developer of the properties. Any legal action would hinge on whether the costs you have incurred are reasonable and whilst you have a technical report giving you one set of opinions, any party you take legal action against would obtain their own technical report which is likely to contain different opinions."In the future, everyone will be rich for 15 minutes"0 -
T
At the end of the day, if you are happy with a solution that means a reduced maintenance cost gravity connection then you have a fair outcome. But I would be very wary of trying to recover the costs of the work off anybody else involved with the pumping station design and construction, including the developer of the properties. Any legal action would hinge on whether the costs you have incurred are reasonable and whilst you have a technical report giving you one set of opinions, any party you take legal action against would obtain their own technical report which is likely to contain different opinions.
My thoughts much like this. I believe you should have gone after NHBC. Their default position is to contest anything so one has to be prepared for a fight. There are clear design requirements here, and design is part of the Technical Standards. However, they will not be a route now because you have commenced work. So they have been let off the hook.
My intuition is the 2011 adoption date is a red herring. Thames Water were never going to adopt a pumping station that was not working correctly. To do so would mean they were funding repairs that were not their liability. This is no different to roads and sewers. They go through a maintenance period as part of the adoption process.0 -
My thoughts much like this. I believe you should have gone after NHBC. Their default position is to contest anything so one has to be prepared for a fight. There are clear design requirements here, and design is part of the Technical Standards. However, they will not be a route now because you have commenced work. So they have been let off the hook.
My intuition is the 2011 adoption date is a red herring. Thames Water were never going to adopt a pumping station that was not working correctly. To do so would mean they were funding repairs that were not their liability. This is no different to roads and sewers. They go through a maintenance period as part of the adoption process.
Furts whilst I value your comment - I'm afraid you are wrong. This has been an ongoing case for some years, every avenue has been explored (perhaps not as rigorously as it could have been) and I reject that the NHBC has been 'let off'. I didn't accept their first response and the case was referred internally. I am copying their response below :
Thank you for providing us with a copy of the report.
To explain, the cover NHBC provides in years 3-10 is for physical damage caused by building defects found in load bearing elements of the home and also below ground drainage that is the responsibility of the homeowner.
It is our investigator’s understanding from the report that the pumping station is not the correct size for the amount of properties that it is serving and as such is not operating frequently enough to be efficient. However this is not due to an installation or construction defect that is causing physical damage and would not be suitable for a claim under Section 3 of our policy.
Approvals given by the Authority that signed off the design and installation confirm the specification and therefore should bear the liability.
Remedial options should be discussed between the builder and the Control body that approved the system.
To clarify on the Thames Water adoption, details of the pumping station and its whereabouts were submitted to Thames Water long before any action was taken on the operation. The eligibility criteria is not met due to the date of commission, not the operation.
As for work commencing now, we dragged this out as long as possible but remedial action has to be taken as insructed by the council and environmental health. The pumping station was condemned over a year ago. Believe me when I say we have not taken this lightly.0
This discussion has been closed.
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