Period Pump

[mattice]

18 months in and it appears our septic tank can't handle the strain of a growing family. Tanks are not large enough, drainage field clogged, and too much clay in the ground.... and no doubt we're using too much water etc. Net result - unhappy neighbours.

Unlike many of you I suspect, we have the option to connect to mains, or so we thought. The manhole is several (more than 5) meters deep and it seems we would need 2-3 of that to remain gravity fed. The contractors don't seem comfortable digging this deep and then having to punch a hole in the side of the chamber.

Unsurprisingly the few (one) contractor I've found willing to connect to the mains is struggling to come up with a solution let alone one not requiring a remortgage. The most likely option at the moment is a pumping station to pump it up the hill (2m head) into a neighbours connection in the road. He''s described dropping a pump into the septic tank with a float switch and essentially having a spare pump on standby... this sounds like a botch, but perhaps out of necessity.

Does anyone have any experience of pumping stations? I'll do my research, I think I've eliminated my other alternatives, purely down to the fact that any treatment system will still have to dispose of the water which my soil conditions have been deemed unsuitable for.

Thanks,

Mattice

PS I was about to post some updates on progress before the above minor distraction, you never know the next project could be a composting toilet

 

[Flyfisher]

How often are you having to empty the septic tank? We try to remember to have it done once a year but tend to forget but it still seems OK for two years. We do have very free-draining soil though.

I would favour a simple gravity system over one requiring pumps, with all the attendant power and servicing requirements, so it's disappointing that your contractor is not comfortable about the necessary digging work. Have they explained why? I would be asking if they are the right sort of contractor because a 3m hole and drilling through some concrete doesn't seem like an overly complex job to me. Not simple, admittedly, but hardly rocket science for a properly equipped groundworks contractor.

We have a large surface water drain running under our land with a manhole about 2m deep. I connected our surface water drains about 1m below ground into the chamber by core-drilling through the concrete wall. It was fairly straightforward once I had dug a large enough hole outside the chamber to drill a pilot hole and then core-drilled the final hole from within the chamber.

I imagine that a 5m+ foul-drainage chamber might require breathing apparatus but I'm sure that any competent groundworks contractors would know about the H&S requirements. As for the external trench for the new sewer pipe, 3m is quite deep and perhaps the contractor is concerned about subsidence, but if the drilling work can be done from within the chamber then it should only be necessary to dig the external trench and not actually work in it (I'm assuming there is access room for a suitable mini-digger). The pipes come in 6m lengths so should easily be able to be laid and pushed through the new chamber hole from above ground, so no risk to any workers from subsidence. Even if the ground is not very stable, shoring up should not be too difficult as long as no one is working at depth. A few scaffold planks would be ideal.

But that's easy speculation when I have no knowledge of the ground and access conditions around the manhole. I would be looking for some other contractors though before completely giving up the gravity option.

I'm not sure about the rules for connecting into the public sewage system but is it possible that the relevant water company could recommend a suitable contractor for such work? When we had a pumped sewage pipe burst under our land, the water company very quickly sent out their preferred contractors to repair it. Talking to their people (very nice chaps who were only too willing to use their 6-ton digger to dig up some large tree stumps and various other bits of heavy clearance for me!), they seemed to work full time on repairing the water and sewage pipe networks and seemed well-equipped for every eventuality.

Perhaps you've already exhausted these avenues but I thought they were worth mentioning anyway.

 

[mattice]

Thanks Flyfisher, some very useful points there and at least allows me to sound more informed. We're emptying the tank annually, it really does look like it can't handle the volume of water passing through due to poor drainage conditions.

I've found some contractors who specialise in deep holes from further afield who will hopefully be more accommodating. Having spoken to them they will need to excavate to the bottom of the chamber and as you say drill through from the inside. We'll see what they come up with.

The water company will not provide a list of preferred contractors, but do seem to want to approve our suggested contractor. Aside from the cost, enjoying the conundrum and I've not given up on gravity as a result of your note!

 

[Feltwell]

I agree with FF. A 2-3m trench should be nothing of concern to any half decent ground works contractor, I've been in far deeper ones. The important bit is that you either need to have enough space to batten the excavation back properly, I.e. so the sides of the trench are at 45 degrees, or if there's not enough room ensure that the trench is properly supported against collapse. It would be incredibly dangerous to go into a trench that deep with vertical sides that was not properly supported.

 

[Flyfisher]

I've found some contractors who specialise in deep holes from further afield who will hopefully be more accommodating. Having spoken to them they will need to excavate to the bottom of the chamber and as you say drill through from the inside. We'll see what they come up with.

If the chamber is large enough to work from the inside and the required drop is only about 3m, why do they need to excavate right to the 5m bottom of the outside of the chamber? I'm not saying there might not be a good reason but it's a question I'd be asking them. But it sounds promising that you have found another potential contractor. I find it's usually possible to gauge whether they are competent by asking lots of questions (which I'm boringly good at :lol: ), many of which may be daft but it's their answers that count. I usually find things work along the lines of 'can you do it this way, no because of xyz, but we could do this instead, that sounds good but what if abc, ah well in that case . . . . ' and both sides home in on a suitable solution. You know what you want but don't necessarily know how to do it while they (should) know how to do things but won't be clear about what exactly you want. A good, knowledgeable contractor will be able to work with you to find a practical solution.

Aside from the cost, enjoying the conundrum and I've not given up on gravity as a result of your note!

At least you're enjoying the challenge - that's half the battle won already

Given that drainage seem to be the basic problem (and I guess the clay soil doesn't help), would it help to build some additional temporary water storage? Effectively a third tank I suppose, or increase the size of the existing one. This would still require that your drainage field to be able to drain all your water usage on average, but it would allow more time. I can't think of a particularly easy way to measure the rate of drainage of the present system though and without knowing that and your average water usage per day, it would be a bit of a gamble to dig additional buffer storage.

Hmm. Perhaps a pump may not be such a bad idea. Or even forget about the septic tank altogether and use something like this:
http://www.drainage-systems-online.co.uk/acatalog/Domestic_Sewage_Pumping_Station.html?gclid=CNCjyura5sACFRHLtAodUl0AeA

The sizing would have to be carefully selected but there must be guidelines about such things. There seems to be plenty of choice.

 

[a twig]

Our neighbours have just gone down the pump route as they hadn't considered the location of the mains sewage connection point when they built their extension.

They've only been back in a month or so - no long term reports but they seem happy so far. Pump was ~£2k, for a ~5m uphill flow. The groundwork delayed their extension build by 3 months though.

 

[mattice]

Thanks all, since, I've been in touch with the water authority and they have agreed I can connect into the backdrop of a neighbours connection providing we also provide a vertical rodding point. Interestingly they almost invited me to put rain water down the sewer as well providing I had a letter from building control. This would really help with my plot and remaining stubborn damp patches, so I'm beginning to see some upside.


The second set of contractors ( a big corporation), were in and out in 15 minutes, didn't even measure the levels, saw the depth of the chamber and felt it was deep enough! Having approval to access an existing backdrop is going to help with the cost, but as you suggested were more than happy digging if they had to. It's amazing how a little bit of reading and some period advice totally change the experience.

The third and final contractor is coming around on Friday. He seemed pretty relaxed on the phone and is somewhere between the other two in terms of size of firm. Let's see what the quotes come in at.

Regarding extending the tank with a third. I was heading down this route earlier in the week and spoke to a 'water engineer' at the local authority planning department. Incredibly helpful, he knew the locality well and had helped out a relative in the same village with the same problems. He advised me to give up the battle and connect. In his words the ground in our village is impermeable and the area is known for its complex network of land drains and random springs. He went on to provide a whole page of advice - I was blown away, I was expecting the SUDS police rather than a totally practical and sympathetic response. My faith is restored - well almost, I've just found out the fees for a few traffic cones

Now drawing my new surface/storm water management plan

 

[mattice]

... and thanks for the pump link, I've been searching for the wrong thing... it's good that we have a fall back plan and sounds better than dropping a pump into the septic tank

 

[Flyfisher]

That all sounds like positive news though, as you say, wait for the quotes to come in.

I suppose that 'dropping a pump into the septic tank' is the same functional solution as that link I found, though if you did go that route then you would be able to disconnect completely from your septic tank and decommission it. That may or may not be a useful consideration in the grand scheme of things.

It sounds like you 'struck gold' with the water engineer chappie. I've had a few dealings with various utilities over the past few years and each time after some initial frustration dealing with people who didn't really understand what I was trying to do, or perhaps were unable to help because the option wasn't on their computer screen ( :roll: ), I've eventually managed to connect with someone who not only immediately understands but also knows how to work 'the system' to make things happen. In every case they've been wonderfully helpful, thoroughly nice people and a pleasure to deal with, reaffirming my basic faith in people and my basic distrust of corporations with systems that impede rather than empower.

Interesting that the water authority encouraged you to use the sewer for surface water. I though they were discouraging that sort of thing these days because of flooding concerns. Perhaps it's because they can then charge you more :wink:

Might be worth checking if this has an implication for either of the pumped solutions as surface water flows probably have very different characteristics than foul drainage. Depending on your roof and other run off areas, flow rates during heavy rainfall could be very high indeed so any pump would have to be suitably sized to cope for the maximum (both in capacity and duty cycle) in order to avoid overflows and local flooding. I'm sure it won't be a practical problem but there will be the inevitable price/performance considerations.

Good luck with the Friday contractor visit.

 

[mattice]

There is now a hole large enough to swallow a couple of cars at the front of the house. The water authority changed its mind once ground was broken and insisted we connect to the bottom of the 5m sewer. Mrs matice said that the digger driver came in for a cup of tea once he'd finished, they were pleased to get the shoring in place :shock: . It's somewhat frustrating to be hostage to the water authority who seem to base their decisions on which side of bed they get out of....

Nevertheless, it's good to get work underway, and a good feeling to get it done 'properly' despite the additional cost. I'm sure there will be more surprises, but at least they will be covered under contract.

It's quite interesting how many neighbours have popped by with tales of underground pipes, springs, water courses, dew ponds. I guess the watery name of the cottage should have been a hint :lol:

 

[mattice]

After many failed attempts to find an old land drain of unknown origin, the digger man found it by chance, where it crosses my boundary, having drained presumably a good acre of the neighbours lawn up the hill first. Isn't it amazing that these old constructions still function so well? I got a camera up it 20m or so and it's clean as a whistle.

I spent the weekend hand digging along the pipe and unexpectedly it made a collision course for the house, made a rapid change of direction and followed along the external wall for a few metres, only a couple of inches underground, before diving off underground to the outlet which constantly pours water under my house somewhere - suspected cause of other damp patches.

I can't explain how much of a relief this is. It's mostly butted clay ware pipe, poorly assembled, so it's no wonder the wall is damp, let alone the fact it's pouring under my house. It's now diverted and I've left the original pipe in-situ in case it was actually performing a function.

Drainage works nearly complete, it's been quite serious with many trenches a good 2m deep as you would expect from my original post. It's going to be interesting if this 2m+ trench around the house, filled with pea gravel, forms an unintentional french drain improving matters further.

I think I've said this before, but this continuous battle against damp is quite satisfying. Time will tell, and I'm looking forward to seeing the tidemarks on the walls recede....one can only hope

 

[Feltwell]

Sounds like good progress! I wouldn't be too disappointed if you don't see much damp improvement until the spring weather arrives.

I wonder why they laid a land drain heading under your house? Unless it's older than the house!

 

[Flyfisher]

I agree. Good progress, but patience needed to see the results.

 

[mattice]

Feltwell, exactly! The land drain is under the 70's extension... They have tapped it into an even older land drain before covering with rubble and then concrete base. It also seems many of our neighbours are 'tapped' into this criss cross network of land drains so we need to keep the flow flowing!

I've been walking the trenches tonight, there's something quite satisfying about drainage