flanagaj

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.

At our recent committee hearing, there was an application for a solar car port. Recommended for refusal by planning officer, but applicant spoke along with his local councillor. The result was that the committee voted in favour and overruled the planning officer.

Is there a minimum distance that you need from a gate to the edge of the highway. I vaguely remember that you must be able to position your vehicle off the highway to enable you to open the gate? As all vehicles differ in length, I am unsure what the rules are around this.

FYI - It's a bit far for you to travel, but I used a company called Salisbury Training Solutions (North Dorset). He did a 3 day 1 on 1 course for me for £1400. It was basically 3 days tailored for a self-builder and avoided all of the red tape for getting your certificate. We practiced digging a soakaway, footings, hard standing and also bank work. Not cheap, but I got to dig holes in his ground and it gave me the confidence to rent a machine, knowing I knew what I was doing.

I am looking at buying one of these. If nothing else, you could use it to simply practice pulling the bucket in level through thin air just off the ground.

So can I assume that as no FFL was specified in the planning application that I can choose the FFL (within reason)? The topographic has a +/- 10cm, eg 122.90 and 123.00. I personally would like to go with 123.00 as it means less excavation. Given that nothing has been specified, what is the legal basis here? By going with 123.00 I do raise the house and remove the possibility of water running towards the house from the adjacent slope.

I thought to myself "What a fantastic idea!", but then realised that the theory only holds if the ground behind is level.

Very useful info. The part regarding tree protection, weeding and mulching is very helpful.

As the fee for discharging conditions is £298, I have decided to try and discharge all of the conditions in one hit. I want to know how vague I can be with the scheme. Our plans showed the general layout, eg, driveway, patio and a few extra trees planted on site. I don't want to employ and ****** consultants and just want to know whether I can simply stick to the approved plans, and detail the driveway surface, material for entrance gates, sandstone patio and make up the tree species. The fact that they want species names, spacing detail .... is all rather ludicrous, especially when most people evolve their gardens over time.

I did an excavator course and I still was unable to grade well. When the material you are grading is loose, eg hardcore or topsoil then it's very difficult. If you are grading an oversite where the ground is compacted, your control inputs are felt more and you can ease off when it starts to bite. A good exercise is to think about what is happening to the boom, dipper and bucket as it moves towards the cab. To keep the bucket teeth in the correct position and level, you need to concentrate on where the dipper arm is in relation to the vertical. As you swing it through on it's arc, you need to be raising the boom. As you pass through the vertical, the process is reversed and you need to lower the boom. All the time you are continually opening the bucket. There is a lot going on and I spoke to an operator who owns a 14 tonne machine and he said he cannot grade at all on a small 1.5 / 3 T machine. Probably because the action on a larger machine is just more controlled and the arc of the dipper is much longer.

We are in the process of trying to find a quality brick layer in Hampshire, but to get a quote we need to decide on what brick bond to use. I think having simply stretcher might look a bit too much like an estate style property and wondered if anyone has some resources or how you go about deciding this. Not sure whether this was the architects job, or whether it is something you decide after you have been granted planning.

One of the conditions of planning is that we have to purchase Nitrate mitigation credits from Eastleigh Borough Council. All I can say, is that I have never had to deal with such a woeful organisation in my life. One woman in the council runs the operation and she does not have a contact number, won't take calls and only corresponds via email (which she never replies too). It took an age to get the credits secured and now we want to purchase them, she has gone AWOL again. It's holding us up, discharging our pre-commencement conditions. I just do not understand, how these individuals remain employed. I work in an industry where responses are done within an hour or two. Has anyone else had to go the process of buying these Nitrate mitigation taxes. Sorry, I meant credits.