The ground it’s dug into should be lower than the building if. Topography, soil characteristics and composition of the effluent should be examined. The soils treated are Organic silt, Varved silts and clays, soft clay, Dredged material The design considerations which should be made are bearing capacity, Slope stability, Degree of consolidation. Country. You should place an impervious layer on top of the. It should be noted that soakaways rarely work on heavy clay soils. This material holds water very well and is easy to find at any local garden store. Country. 60 100 6. #1. The average pH value in natural organic soil amendments ranges from 6. Alternately, gardeners can build berms in the landscape to lift plants out of poor-draining clay. Use water butts to collect rainfall. Dig Out the SiteDig out a 600mm x 600mm patch of ground, about 3-4 inch below the height of your grass. Fill around the sides and top of crate soakaways with a good, compact layer of sand or gravel, before backfilling with soil. if your ground is relatively free draining then building control will insist upon a soakaway if practical. 87 40 2. And that’s just one example of how different soil types can affect land. A traditional soakaway will have a ratio at the higher end of scale where it drains a road or several houses. In a clay soil it’s going to take a long time for any soakaway or finger drains to empty so you need to size them accordingly. Soakaway Size. The first thing to consider when choosing a suitable site for a soakaway is the water table. Step 1. Hierarchy for surface water drainage is soakaway, surface water drain, foul drain. Be sure not to overdo it with peat moss as it is important to add sand or perlite when using peat moss for it. Instead, the water will collect in the soakaway hole and begin to seep back out into the soil around your property. Put 2cm of soil in a large jar filled with water, screw on the lid and shake. However, the consolidation of the soils is time dependent, delaying construction projects making it a non-feasible alternative. With nowhere for the water to go to it just fills up and sits there. Due to its nature, vermiculite prevents mould. Soakaway won't work - what alternatives do I have? Temmy; 15 Sep 2021; Roofing and Guttering;. The soil in which the soakaway is placed must be granular with good drainage properties. Fill the hole up to about 100mm (4in) of the top with. This is the saturation line or upper level of groundwater within the soil or bedrock, which can rise during rainy seasons and fall during dry spells. This is due to the voids within the soil becoming blocked by fines and sediment. 5 metres from a boundary etc. Heavy clay soils, like black cotton soils and soils prone to surface sealing, hold moisture for long periods, meaning they become waterlogged easily. A soakaway is something you can build yourself, but there are a couple of things to be aware of before you get underway. Soak Away Testing. 25 Mar 2015. Log In. While we recommend your groundworker conducts a soil percolation test and creates a set of calculations, there is an alternative method that will give you a rough idea of the soakaway size you’ll need: If your soil type is not too heavy/clay, you can assume that one crate (1000mm L x 500mm W x 400mm H) will be sufficient for ten sq. I dug a channel out and have begun to dig a soakaway in the corner of the garden and am down about 1 metre so far, just gone past blue clay. Regrading the garden slightly to have the water run down to one side. Country. put soil, sand or similar material on the driveway that will block the surface and stop water soaking in. A traditional soakaway will have a ratio at the higher end of scale where it drains a road or several houses. A soakaway is basically a deep hole filled with rubble. For this reason homogenous clays are generally unsuited to soakaways as they can have very low infiltration rates. DON’T install a soakaway in heavy clay soil, the water cannot drain through this so it won’t work if this is in your garden. If above ground the condensate pipe must be protected with a waterproof lagging. Log In. All clay soils become easier to work with if you add organic material. The rate of this silting depends on several factor but principally the following. It allows water to filter through it, and literally soak into the ground ( away ). pH value of natural organic soil amendments. While digging the hole, look out for changes in soil characteristics. Log In. How deep should a soakaway be in clay soil? 1. To work, it must extend below the clay and be at least 1. A lot of sites say that adding sand to clay soils means the clay aggregates around the sand and sets like concrete. A soakaway is a hole that’s dug in the ground and filled with coarse stone, rubble or plastic crates (also known as soakaway crates ). Infiltrator Water Technologies is a market leader within the onsite wastewater treatment industry, Infiltrator manufactures a variety of revolutionary products and innovative, environmentally friendly alternatives to traditional stone and pipe leachfield and concrete septic wastewater system components. If it takes one to two hours for the. The correct fabric for wrapping soakaway crates is a high-quality, non-woven geotextile, such as Draintex from the Product That Works range of professional landscaping products. 49 50 3. 1,009. The first step in designing a soakaway is to conduct a percolation test. Chapter 3 1994 8. Alternatives for Heavy Clay Soil. Figure 5 shows contours of the interface between the Upper Chalk and the overlying Clay with Flints at a site in east Kent. Fill the test hole with water to a depth of at least 300mm. Based on. tomfe. Aug 6, 2014. Once wetted by winter rains, clay soils often cannot be worked or walked on until mid-spring. Where digging is required, it is traditional in wet regions to dig clay into narrow ridges to. The ideal garden drainage solution depends. * You can't stop it raining, * You can't pipe it out of the garden. you can go as close as is practical to the hedge. Vegetation – Dense vegetation on a rural surface can intercept and store a significant amount of rainfall, thereby reducing the catchment runoff. 20 for sewage treatment systems. Value proposition. you are now not allowed to run storm water in to fowel drains. The permeability of the soil is akin to the size of outlet in the system I proposed above. These fibers are an excellent material since they help orchids grow strong roots that can hold the plant together. Using a pothole digger or soil auger dig a hole four feet deep. Other than that it depends on how much water the soakaway will be processing and the perculation rate of the surrounding soil – i. If you need to do a percolation test then: 1. 8m deep. P = the maximum number of persons that the treatment system/tank is designed to serve. They consist of a perforated pipe surrounded by gravel to facilitate water movement. I'll be doing that and if I get a positive result, pressing on with purchasing the rainwater crate. Materials that compost quickly include well-rotted manure, leaf mold, and green plants. 5m deep in a lower part of your garden and preferably at the bottom of a slope. Also not every garden has the facility for a soakaway, some are paved over, concreted or whatever. 8m deep. To do so, we’d recommend using sand or shingle material. When wet conditions cause clay minerals to expand wastewater. Is your septic tank and soakaway in clay soil? Are you installaing a septic tank and soakaway into clay soil? Would you like free help and advice about installing septic tanks and soakaways in clay soil? Then watch this video. Pre-settled effluent from a collection and storage/treatment or (semi-) centralized treatment technology is discharged to the underground chamber from which it infiltrates into the surrounding soil. orCalcium-based binders, such as ordinary Portland cement (OPC) and lime (CaO), are the most common artificial cementitious materials used worldwide for concrete and soil improvement. Paving reduces or stops rainfall getting into the ground. Digging in a 1m3 soakaway using a soakaway crate near the centre back of the garden (at least 5m away from the house and 2. A soakaway is a common drainage solution for many properties in the UK. The pipes or chambers are laid in trenches or gravel beds and covered with soil, ensuring proper drainage and permeability. 5m away from the garden wall). Can be used independently or as part of a larger system to collect and detain stormwater, allowing for groundwater recharge. If the water clears within half an hour, you have adequate amounts of gypsum. It promotes the rapid growth of roots and plants in general. The side drains join the main drain at a 45 degrees angle and are spaced at 10 ft intervals for clay soil and 25 ft intervals for loamy soil. What are your options if you have a septic tank in clay soil? Unless you have another area within your property's boundary which does not have clay soil, then a soakaway system or drainage field is unlikely to work. If you are hoping to create a soakaway to alleviate waterlogging in a garden, you may well be disappointed by what follows. dustmaker said: building regulations state that a new soak a way has to be at least 5. When used with other mediums, it increases the retention of nutrients. We have heavy clay soil so the soakaway gets full and floods in heavy rain. - Dispose of wastewater in a soakaway pit, an evapotranspiration area or an irrigated garden (see relevent technical briefs). 4. 0m can become difficult and more expensive to build. septic tank soakaway clay soil - septic tank soakaway clay soilyour septic tank and soakaway in clay soil?Are you installaing. Pre-settled effluent from a collection and storage/treatment or (semi-) centralized treatment technology is discharged to the underground chamber from which it infiltrates into the surrounding soil. One of the drains at the front of the house leads to a soakaway which was quite old and flooded when the rain came. A Soakaway must be at least 5 metres from any habitable building, by local authority regulations. Soakaways and alternatives. Dig a series of parallel trenches every 3-6m across the garden, sloping towards the ditch or soakaway. 3 Improve drainage in heavy soil. pinenot. This option is super popular for crafty hydroponic gardeners on a budget. Water-loving plants like swamp milkweed ( Asclepias incarnata; pictured) or cardinal flower ( Lobelia cardinalis) both beautify and improve poorly draining areas. line the hole with geo fabric. Add a gradient. This can cause wastewater to flood the surface of your property. Put 2cm of soil in a large jar filled with water, screw on the lid and shake. If you're going for traditional concrete or another hard surface for your driveway, it will need to be built on a slight gradient. 4m deep (hit rock) As you can see from the pictures, it looks like clay and certainly acts like clay. approx 1800L per day like some technique to send the water into earth or is there. If the sediments entering the soakaway are the same size or larger than the pores in the infiltration medium then the sediments do not significantly affect the infiltration rate through the soakaway. A soakaway may well be pointless in heavy clay and therefore your only other option would be to run the water off the surface and round a corner to a bed or lawn etc, depending on the surface area being drained this may not be suitable but for a small drive it would probably be ok. I'm trying to come up with a. Soakaway crates · June 30, 2020 · · June 30, 2020 ·newcastle phill. These types of soakaway are useful where a very good infiltration medium underlies a deep layer of poor infiltration material, such as gravels underlying a deep. The reasons for septic tank and soakaway drainage field failure 1. So the two are totally different and adding sand to clay doesn’t mean it will set like. Settlement of the Made Ground could result in settlement of the inlet pipe into the soakaway, opening of joints and water leakage. The way to determine the type of soil and how porous it would be is through a percolation test. Once the back, side and top is covered with 150mm of pea shingle, then you can add the top soil – usually a minimum of 400mm. Dig a hole 300mm square to a depth 300mm below the proposed invert level of the incoming pipe. A soakaway is basically a deep hole filled with rubble. wcavanagh. Garden or driveway soakaways are usually much smaller than. NB: Due to size constraints, developments in urban areas are sometimes not large enough to use a soakaway. The pipe which runs to your soakaway/crates will either come. Normal soakaway drainfields will not be able to soak wastewater away into clay or clay-based soils because of their porous nature. bark as final layer. Fill with water to depth of 300mm. 5: Other Soil Amendments: Use With Caution. This will help to keep the crates in a secure and stable position, but it will also help to allow the water to soak out of the soakaway drain. And it could be right if we consider that concrete has sand in it. 5 metres is just from the building in any direction, it doestn have to be away from the sides. This includes the top and the bottom! If your soakaway is covered by soil or lawn you will need at least 200mm of topsoil on top. A cone of influence of 450 from the discharge points in a soakaway surrounded by soil with similar vertical and horizontal permeability can be used to provide an initial assessment of the zone of impact of a soakaway. I think with the soakaway as specified you will end up having to land drain the field anyway and there will always be a soft spot over and around the soakaway hole. Finding alternatives to natural resources is important for a sustainable future and is essential to infrastructure projects. If the water table is too high, then a soakaway simply won’t work there. The downpipe runs vertically from the fascia for. Save time and money with one of the UKs leading soakaway and site investigation experts. The excavation can proceed in a similar manner to any deep drainage excavation. 5%. Soakaway Nightmare, Clay Soil. changed your discharge from surface water to ground. soakaway. If the soakaway has been constructed in non-permeable soils such as sandy clay, silt clay and clay then the effluent from the septic tank cannot filter away through the soakaway then flooding of the septic tank will occur causing it to overflow, causing a health hazard. Required storage volume in the soakaway, SSoil organic carbon dynamics: Impact of land use changes and management practices: A review. dustmaker said: building regulations state that a new soak a way has to be at least 5. In other words, 1 crate should be used for every 10-12m2 of. #2. Log In. Dig. e. 0m deep. Cut pool noodles: A cut pool noodle can also be used as an alternative to hydroton. Dig a series of parallel trenches across the garden every 3-6 meters, sloping toward the ditch or soakaway. Calcium-based binders, such as ordinary Portland cement (OPC) and lime (CaO), are the most common artificial cementitious materials used worldwide for concrete and soil improvement. To perform a perc test, pick a spot along the path of your planned drainage system where you hope to locate a drywell anyway . This is most common if the membrane is broken, the crates are the wrong size or capacity, or the pipes have. As an alternative to using gravel consider the prefabricated crates below. Some septic system options for expanding clay soils include. The best garden drainage solutions usually consist of a french drain system leading into a pump station which redirects water into a surface drain. The two determining factors for soakaway success are the size of the area (or volume of water) to be drained and the percolation rate of the soil/sub-soil. Soakaway Nightmare, Clay Soil. Soils with a clay/silt content greater than 40% are. A soakaway is part of the Sustainable Drainage Design. If a soakaway is impossible to achieve, you may be able to discharge the water into a local watercourse if you live next to one. The volume of water being put into the soakaway: If a soakaway can't handle the water quickly enough then it will silt up at the bottom and eventually the sides will collapse. See more of Septic Tank Soakaway Kit on Facebook. We provide National coverage. As well as the back and side fill, a layer is also required on top of the soakaway crate, before the hole can be re-covered with soil and any other finishing. In a clay soil it’s going to take a long time for any soakaway or finger drains to empty so you need to size them accordingly. Beg some plastic milk or beer bottle crates, wire them together to form a cube, wrap it in horticultural ground cover fabric and bury it in a pit, running a rainwater pipe from the middle of the crates to the outlet of the drainage channel. Till or loosen your clay soil to a depth of six to 12 inches, then spread a four-inch layer of perlite across the top. Thangavel Ramesh,. We share our downpipe with our neighbours so we are taking a lot of the rainfall. Crates measures 800x500x540mm = 0. 2. Make sure the topsoil is set to one side and the poorer draining material is discarded. Digging with a sturdy spade is the best way, but using a rotavator works OK too. Note that sometimes, especially after heavy rainfall, accumulated surface water may not drain as fast as usual. Fill your soakaway. A soakaway system is an online system whereby all storm water flows into the crate structure and infiltrates into the surrounding ground as and when saturation allows, until the crate structure is completely empty. 4) Dig up the entire garden and mix the soil. mix concrete on the driveway. A soakaway is essentially a point feature; it does not have a channel. 262 months. Soil that is mixed with peat is much less dense. 2m (4ft x 4ft x 4ft). Because your soil is clay a traditional rubble filled hole will not be an adequate soakaway. It behaves like lignin (decomposed wood cellulose). soils that are prone to swelling and shrinking) can cause structural damage to underground septic systems, which may require costly repairs. This excess water will eventually soak into the ground well. There are not many options to clean or clear a blocked soakaway if you are planning on carrying out the work yourself. The pre-fabricated soakaway system offers an alternative to gravel when installing a French drain garden drainage system. Essentially, the poorer the drainage, the bigger and deeper the hole needs to be. Too much pressure put on the garden with all rain surface water going in it from all the rain and surface water. This is a more complex project, and the extra costs reflect the difficulty in lifting sections of a driveway and the deeper hole. How do I install a soakaway in my garden? Follow these 6 simple steps to install soakaway crates – both quickly and correctly: Step 1 – Create space. It is worth mentioning that certain soil types like heavy clay will be unlikely to allow sufficient water drainage for a soakaway, while sand, chalk and limestone based soils are likely to be suitable. bennno. Allow the top of the soil in the pot to protrude 1 inch above the soil line. Soakaway crates take run-off water and allow it to slowly percolate. This is best done using shingle or sand, which needs at least 6 inches to be placed around the sides as well as on the top of your crates, before (for gardens) at least another six inches of any soil which was removed to make space for the crates is added back on top and. Soakaways are viable for clay soils but normally need to be be another size up- (greater storage for later attenuation), for instance I know Aquacell quote numbers of. Installing a channel drain starts with a narrow trench cut into the concrete or asphalt. It’s most commonly used as an alternative to perlite for its. Use coconut fiber (fibers extracted from the outer part of coconut) to custom make an orchid mix. 0151 515 1415; hello@spudulica. filled the hole at 1820, and by 2217 it had possibly (possibly) moved 2cm, but I suspect. at least 5 metres from a building or 2. Quote 2 involves lifting sections of a driveway and path, installing the soakaway to a deeper level to bypass the clay soil and finishing off by re-laying the sections of the driveway. clay lumps and friable particles. Soils with a clay content of more than 20% are generally unsuitable for infiltration. Soakaways are used to manage surface water at its source, and serve as an alternative option to draining off surface water via a stream or sewer system. septic tank soakaway clay soil - septic tank soakaway clay soilyour septic tank and soakaway in clay soil?Are you installaing. It strengthens root anchorage. 3. A soakaway is best installed away from the house, but it may only last a few years. Luckily, there are a variety of solutions for improving drainage in heavy clay soil. Consequently,can you have a soakaway in clay soil? The excavation for the soakaway is usually done by mechanical diggers. 3m deep and 1m x 1m. Well if you have a shallow clay cap on an otherwise free dining soil that might well work. Step 3 – Prepare the base. The deeper the soakaway is the better its infiltration performance and storage capacity. Water-loving plants like swamp milkweed ( Asclepias incarnata; pictured) or cardinal flower ( Lobelia cardinalis) both beautify and improve poorly draining areas. 06 (i. this has lead to storm and in some cases sewer drains being overwhelmed. Staffordshire. The Infiltration Rate of Soils also tends to decrease over time. 5m deep in a lower part of your garden and preferably at the bottom of a slope. Among these replacements is the use of coffee waste as soil stabilizers. Here is a statement from Trent Water: Mound systems work well as alternatives to septic tanks when the soil around your home or building is too dense or too shallow or when the water table is too high. Refill the hole and time how long the water takes to seep away from the 75% point to the 25% point (this is 150mm). To determine. The above Infiltration Rate of Soils values will be suitable for an initial or feasibility design, but detailed design must always take place based on site testing. Like a trench drain, a swale is a surface water drainage device. 45 mm. Make sure your pipe slopes towards the soakaway. Beg some plastic milk or beer bottle crates, wire them together to form a cube, wrap it in horticultural ground cover fabric and bury it in a pit, running a rainwater pipe from the middle of the crates to the outlet of the drainage channel. The water the soakaway collects will drain into the soil below the layer of hard clay. The soil was available in powder form with particles smaller than 75 µm. They put plastic based fences all the way round and laid turf. That said & having read the main site & some of the forum posts, I have some questions about soakaway alternatives for our garden. In many cases, sites with a high water table or a heavy clay content will also not be suitable. It should be noted that soakaways rarely work on heavy clay soils. Work the compost into the soil down to the top six inches to one foot by hand with a garden fork or a spade, or you can use a tiller. It should be noted that soakaways rarely work on heavy clay soils. Drainage trenches can be particularly useful in clay soils which are easily compacted. Country. #1. Start by digging the standard 1m x 1m x 1m trench, increasing the size if necessary,. While there are a great many organic soil amendments, for improving clay soil, you will want to use compost or materials that. Similarly some silts are also largely unsuitable, though this depends on the particle size. Do not use fine-grained sand as it will just. 9. A Soakaway is a pit or trench where surface water is allowed to collect and slowly soak into the surrounding soil or rock. Installing a soakaway involves careful planning and adherence to local regulations. Water in camps of Displaced people 1994. uk; Order In Next To Get It On Sep 14A soakaway works by encouraging rainwater to flow quickly through the soil into a hole or pit created. The crates feature voids, allowing large volumes of water sufficient surface area to seep back into the ground. A soakaway system enables you to collect water and then slowly disperse it into nearby soil without creating excessive runoff and overwhelming the underground drainage systems, which is particularly important in areas with higher than average rainfall, hard ground or steep sloping ground. Septic tanks must always be subjected to a percolation test before they may be. I'd have thought once you removed all the top soil and roots etc down to the sub soil and get 100+ mm of well compacted hardcore, it doesn't matter how soft the underneath is. The pipe end entering the soakaway must be at a depth of 25mm minimum and the end of the pipe cut at 45°The current study aimed first to examine the mobility characteristics of Cu, Zn, and Pb through soil and soakaway sediment using an integrated analytical approach for column leaching with. Ello, I've been trying to sort out the rainwater drainage at the back of our house. Put bag of clay in bucket. 74 70 4. 50m from water abstraction points, boreholes, springs. A soakaway crate is used as part of a full drainage system in areas that experience high levels of surface water or run-off. The soil in which the soak away is. If there’s a lot of water and it doesn’t drain too quickly, then it should be bigger. Plastic chamber leach fields are great alternative septic systems for small lots and properties with high or variable groundwater tables. #2. Nature of the soil and its effect on the soakaway drainage field performance It is impossible to soak effluent away into a clay or clay-based soil in a normal soakaway drainage field. Ground where water soaks away too quickly (e. Soil sodicity. These husks also improve moisture retention but help in draining it quickly. The diagram below is not to scale. In our first spring season, we noticed the garden was very waterlogged and pestered the builder who eventually installed a soakaway in the garden approx 1 metre from the back of the house. As an alternative to using gravel consider the prefabricated crates below. It takes approximately 5. A deep bore soakaway is a special type of rainwater soakaway consisting of a conventional chamber and a narrow bore perforated liner extending to the infiltration medium. It's also soft rather than scratchy underfoot, unlike edible thyme varieties. How to Build a Soakaway in Clay Soil? A soakaway is basically a deep hole filled with rubble. 28 Mar 2008. Free call for quote on. Peat Moss. T. See more of Cesspit on Facebook. Dig a large hole in the ground, line the sides with heavy-duty landscaping fabric, to keep the earth from over time clogging up the gravel. This can be an expensive and arduous effort but is generally fool proof and really the only option if you are trying to grow on pure clay. ”. I know we have a lot of rain lately, but the garden is. As sodium salts are leached through the soil, some sodium remains bound to clay particles—displacing other cations. When used with other mediums, it increases the retention of nutrients. Sodicity in soil is the presence of a high proportion of sodium ions relative to other cations. This leads to aerobic digestion and effectively treats the effluent. If the ground is unsuitable, like clay soils are, localised flooding can occur due to waterlogging. Soakaway problems have a range of causes, many of which can be hard to diagnose without thorough investigation, training and. some clay soils) may not be suitable. Typically developments situated on soils with a high clay content tend not to be. In Australia, a soakwell is a large underground plastic or concrete tank that connects to your roof drainage system. On sloping ground soakaway trenches should be constructed at a constant depth along one or more contours. Hole 300mm square to depth of 300mm below where pipe will go into the soakaway. For this purpose, soil (n = 2), “soakaway” sediment deposited in the artificial infiltration facilities (AIF) (n = 4), and road dust (n = 2) were sampled from Tokyo metropolitan. Rainwater soakaways are usually made from gravel or stone or even plastic soakaway crates. 4. septic tank soakaway clay soil - septic tank soakaway clay soilyour septic tank and soakaway in clay soil?Are you. Alternately, gardeners can build berms in the landscape to lift plants out of poor-draining clay. However, if you are interested in trying to retain that water or have it distribute into the soil without muddying everything, you can create a soakaway pit to collect water. In contrast, clay soils and hard-packed or rocky soils are. This is useful if the soils are clayey and do not drain very well. Step 2. As an aid, mark a stick 300mm from one end, place in the hole and fill up to the mark. When it comes to the hardcore infill, it should totally surround the pipe and rise to around 100mm above it. This year, for the first time in about 40 years my parents garden flooded. allow the garden. When rainwater floods into the same area time and again, a little light geoengineering may be the solution. See full list on gardendoctor. How a French Drain Works - in Clay Soil. The test procedure is outlined here. Consult your local planning department. Soakaways in impermeable soils are unlikely to function because they just fill up with water, so an alternative method of disposal is required. Is there an alternative to a soakaway? If a soakaway is impossible to achieve, you may be able to discharge the water into a local watercourse if you live next to one. soakaway. g. land drain and soakaway details sd 8-2-307 march 2020 11 1:20 on a1 9 drawing title: drawing number:. #10. Again though, not sure if these would likely just fill with water like a pond and leave puddles in the garden and how effect the water would feed into them. Whether you’re using crates or stones for your soakaway pit, be careful not to spill soil inside your geotextile lining as it won’t work effectively. Clay soil, constantly wet from a soakaway will become a quagmire and make the feild close to unusable for much of the year. Soak pits are appropriate for rural and semi-urban settlements. The Plant Company often uses a mini-excavator to complete this task as the bigger the hole, the. ALL parts of the soakaway drainage field are required to be a minimum of: 10m from a watercourse or ditch. As part of my building extension planning proposal I intended to create a soakaway to accomodate the extra surface water. If using proprietary compost mixtures, follow the instructions on the package carefully. #1. option 2. When is a soakaway possible? A soakaway is possible when: The ground infiltration rate is greater than 1×10-6m/s. Its all to do with the tiny gaps between the particles in the sub soils through which the waste water passes. Dig a series of parallel trenches every 3-6m across the garden, sloping towards the ditch or soakaway. The required volume of the soakaway and the volume of the storm surge attenuator are calculated in similar ways.