flanagaj

But we had to purchase Nitrate Mitigation credits. Said credits were calculated using Graf's certified value of 7.9mg/l and the Solido was 10mg/l No. But I will have a look. Thanks

The issue with the Graf, is the depth of the install. I am really liking the sound of the Rewatec Solido Smart. This is apparently super quiet and a shallow install. Only annoying problem. Our planning condition states we have to install the Graf One2Clean. Given the Graf has Ntot of 7.9mg/l and the Solido is 10mg/l, I'm sure any change will require me to shell out more ££ on their Nitrate mitigation taxes.

The architect specified a granite sett to the road, but I am unsure who can install this and whether it requires a drainage channel before the road. We live on a no through lane, but the council do appear to own a section back from the road edge (hence the not sure). There was nothing mentioned in our planning conditions and only the "hard and soft landscaping" condition might be relevant.

🙄

If they say you have too many and you have to remove some of them. Does that mean you have to resubmit to discharge the condition, or is it merely a negotiation process between you and the planning department?

My aim today is to try and create a report to discharge the condition below. "No external lighting shall be installed on site until details of any lighting have been submitted to and approved in writing by the Local Planning Authority. The equipment shall be installed before the development is first occupied/use commences and shall thereafter be operated and maintained in accordance with the approved scheme. REASON: Details are required prior to any lighting being installed because insufficient information has been submitted with the application in this regard, in the interests of the visual amenities of the area, in accordance with Policies EM1, EM10 and EM12 of the Basingstoke and Deane Local Plan 2011-2029." I am conscious that as we are in an AONB, any proposed lighting needs to be < 3000k and be directed downwards. I am concerned about fitting PIR lighting as I don't want it coming on when animals are in the vicinity. The only reason I thought about PIR was for when you arrive home late and it's dark, or you are going out and want the lights on until you get in your car. Are there wireless options for a key fob or a smart phone app that you can use. This would be ideal and you could then turn the outside lights on remotely and therefore negate having PIR sensors.

I am known to procrastinate!

A non extraction well next door has the water table depth at > 20 metres, so should be ok. But I take your point.

I am aware of that. But that is not what I am trying to ascertain.

Here are two different ways of installing a drainage field. The separate trenches requires considerably more space to create the same m2 field, when compared to the excavated rectangle. Question is. do they actually perform the same? I would hazard a guess and say that the separate trenches is a much better design to the other one.

I’m installing one shortly and as we are not in a high water table area, I’ll be backfilling with pea gravel. The concrete backfill is a terminal operation and cannot be undone.

The infiltration tunnels can store a large volume of treated water. I assume it then means the water can dissipate over night from the tanks, where as a conventional field can store a much smaller volume of water in the pipes. Maybe I’m talking nonsense, but I get your point.

Can I ask what the cost of the permit was? We are not in a SPZ1, but whilst I can fit a drainage field into the space. The logistics of excavating the area is going to be difficult and if I am honest, a right pain to remove so much spoil. Hence, my motivation to see whether I could instead use the infiltration tunnels.

Yes. It is the Graf infiltration tunnels as stated in the post you have linked to. I doubt they are BS 6297:2007 as that is the GBR. Which is why Graf are saying that some councils are ok with them being installed and others are not. Maybe said councils should be requiring a permit in all instances.

You can go shallower, but I think you need to cap the pipe with concrete.

Can anyone explain to me why you can design your drainage field in one of two ways. For example, say you have calculated your drainage field area at 24m2. You could go with one of the two options below. 1) 40m of trench at 600mm wide and create something like below. 2) Excavate a rectangle of 8m * 3m and fill the whole base with appropriate gravel before laying the pipework. Now option two will have a lot of gravel in the middle of the drainage area that is some distance from the pipework, where as option 1 does not have that. Maybe overthinking this, but I suspect that if you did field tests, you would get different results from the two options. I don't have the space for option 1 and option 2 is going to be difficult as I don't have a lot of space for moving the excavator around. I did speak with BC regarding infiltration tunnels, but they simply told me to apply for permission from the EA. Given it's > 2k to apply for a permit and it seems like a lot of work, i think I will just have to go with option 2. It's rather frustrating, as Graf told me that some councils are perfectly happy with the infiltration tunnels, so long as you are not in a source protection zone.

Can I ask a few questions. 1) What was the cost to apply for a permit to discharge via infiltration tunnels? 2) Do you have to pay an annual fee for the permit? Only reason I ask, is that I can fit a drainage field of the required size on our plot, but it is going to be a right pain moving the excavator around and digging the required trenches. An infiltration system requires much less excavation and will be a damn sight easier to install.

I love the look of metal sheet piles just as they are, but I suspect I'll struggle to find a company that will do them. I haven't ruled out RSJ with horizontal sleepers. They should be quick and easy to install too.

Yes, we are retaining the hedge. As a side can you tell me how the underground drainage works if you come directly through the outer and inner skin and then immediately go to vertical? Our floor make up is 100mm slab / Dpm / 200mm celotex / 50mm sand blinding / 150mm hardcore. If I add that all up, I get 500mm. If I then start my underground drainage with an invert of 610mm, I am already deep and with a 24m run to the STP, I'll be too deep. So I'm assuming that I can come into the house at a level higher than 500mm?

When you say reinforced concrete wall, do you mean hollow concrete blocks with vertical rebar, or a cast concrete wall using plywood forms? Depth of soil ranges from 300mm to less than 900mm We wanted to run the drainage down the back of the property, so unless we move the drainage to the front of the house, there isn't a great deal of width for wall footings. Width from back of house to boundary is 1.2m

I am investigating retaining wall options for a wall that will be tight up to the field boundary which currently has a hedge owned by the neighbour. Gov website clearly states that when it comes to hedging you can dig down and cut up vertically. So not worried about digging roots up to pour concrete footings. The main issue I have is that the wall needs to be as narrow as possible as we don't have much space down the back of the house. Sleepers are narrow, and won't last and a six inch block wall will take up considerably more width. As the wall is less than 900mm, I was contemplating pouring a cast concrete wall, but unsure how I'd go about designing it.

This link was very helpful and clearly details my question regarding drainage fields / infiltration tunnels for a STP. "Currently, written legislation has fallen behind the technology available, notably in Sewage Treatment Plants. Sewage Treatment Plants produce near clean water, thus the need for secondary treatment is redundant. A Septic Tank with a Drainage field is nearly always cheaper than a Sewage Treatment Plant with a Drainage Field. Written legislation allows you to build a slightly smaller drainage field but the impact is minimal. Essentially a rational economic person would not install a Sewage Treatment Plant with a discharge to ground and a Drainage Field. While explicit written standards have not caught up, building control and local authorities have. With consent, it is possible to install a series of Infiltration tunnels to discharge the treated effluent from a Sewage Treatment Plant. Again there are calculations to perform based on porosity etc to ensure an element of secondary treatment and adequate dispersal. A Sewage Treatment plant with an infiltration system is generally cheaper than a Septic Tank with Drainage Field. Further, an infiltration system can be installed in a far smaller area increasing flexibility and applicability. For instance, the majority of Septic Tanks currently do not have a Drainage field that meets the general binding rules. The Environment Agency is unlikely to check on your Drainage Field. However, when you come to sell your house or replace a failed Soakaway a Drainage Field will need to be installed. Drainage fields cover a large area, in most cases four to five times the surface area of a traditional Soakaway. Many properties with Septic Tanks do not have sufficient space to install a Drainage Field constructed in line with legislation. A Sewage Treatment plant with an infiltration tunnel system could be the only viable option."

This is where it gets confusing. My understanding is that a sewage treatment plant does primary and secondary treatment. That therefore negates the requirement for the aerobic treatment provided by the soil.

Correct. There are no water courses within the vicinity of the tank. Hence, discharging to ground.

So I am reading a lot of conflicting information regarding whether a STP needs a drainage field. If I am correct drainage fields are historically used for septic tanks, but if you read section 5.3 of NHBC-Standards-2025-Chapter-5-3-Drainage-below-ground.pdf you see that they mention discharging to a soakaway. Interestingly, they make no mention of a the percolation test draining away too quickly (like one of our trial holes). So what is the actual requirements for discharging from a STP if you cannot discharge to a water course? Ideally, I'd like to be able to use soakaway crates or the Graf infiltration tunnels. Our site is quite tight and excavating and installing a conventional drainage field will be tricky.