Rainwater Harvesting Systems: A Sustainable Solution for Water Conservation
Explore our comprehensive FAQs portal dedicated to rainwater harvesting systems, an innovative approach to water conservation. Discover how these systems collect and store rainwater from rooftops, enabling you to reduce your reliance on traditional water sources. Learn about the various components involved, including storage tanks, filtration systems, and distribution methods. Gain valuable insights into the benefits of rainwater harvesting, such as reduced water bills, improved landscape irrigation, and mitigating stormwater runoff. Whether you’re a homeowner or a business owner, this guide will equip you with the knowledge to implement a sustainable water management strategy for a greener future.
An aboveground rainwater harvesting tank is easier to install and maintain, and it may be more cost-effective. However, there are advantages to burying the tank underground. Firstly, being underground provides a controlled environment that minimises UV exposure and temperature fluctuations, preventing the growth of microorganisms. Secondly, an underground tank saves space as it can be installed discreetly in a garden or driveway, allowing other uses like parking. It offers a more integrated solution. Additionally, the maintenance of underground tanks, like the ECO-Plus system, can be facilitated by external control elements. It’s essential to consider all options and choose a rainwater harvesting solution that best suits your specific requirements and desired applications. Proper understanding and consideration will lead to a more suitable and satisfactory choice.
When it comes to the maximum distance a pump can be located from the property, it depends on the type of pump being used.
For submersible pumps that are installed within an underground tank, they typically have good pressure and flow rates. Most domestic submersible pumps can handle 4,000 litres per hour or more, which is about one to one and a half litres per second. With a 40-meter head of pressure, you can generally expect a range of up to 40 meters vertically or 400 meters horizontally, although there may be some variations due to pipe work.
For most domestic rainwater harvesting systems, a submersible pump is sufficient to supply water over considerable distances. However, it’s important to note that if multiple outlet connections are open simultaneously, there may be a slight drop in pressure and flow rate, favouring the closest outlet.
Considering typical property heights and the possibility of pumping water back into the property for different applications, it is feasible to have a property located around 300 meters away from the underground tank.
It’s worth mentioning that if you have a wall-mounted pump console inside the property, the underground tank should be located closer to the console. This is because the pump console relies on sufficient power to draw water from the underground tank. The 40-metre head of pressure provided by the pump can still push the water over long distances, but the proximity between the tank and the wall-mounted console needs to be considered more carefully.
No, rainwater harvesting is not illegal in the UK. In fact, it is encouraged by councils and there are regulations in place to ensure its safe and proper usage. However, it’s important to consider health and safety aspects such as preventing cross-contamination between rainwater and mains water. Labelling rainwater outlets is recommended, especially in internal systems where accidental consumption by children may occur. It’s worth noting that while rainwater harvesting is legal in the UK, there may be misconceptions due to certain US states where it is restricted or prohibited. But in the UK, you can confidently pursue rainwater harvesting without any legal issues.
With the Graf system, accessing the water in your underground tank for the garden is made easy. You have multiple options for external connection points, such as plumbing for outside bib taps, internal hose connection points, tap pillars, and even connections to fountains. The pump in the tank operates when there’s a demand for water, and you can connect multiple outlets simultaneously, considering the flow rates. The design of your project will determine the placement of outlet points, whether it’s at the front, back, or even remote locations in the garden. The standard garden comfort package includes an internal hose connection box, and there’s also the option for an external hose connection box placed farther down the garden. These accessories can be added on to suit your specific needs. Tap pillars are available in plastic and stainless steel, offering a wide range of choices to extract water from your tank easily.
Yes, the underground tank can be connected to an external tap. The primary application for rainwater harvest systems is outside irrigation, allowing you to easily water your plants with rainwater. Installing an outside bib tap is straightforward, with a feed line connected to the pump in the underground tank. When you turn on the tap, water is supplied, and when you turn it off, the system shuts off. This setup is not only useful for garden irrigation but can also be used for tasks like washing your car or cleaning external surfaces. It’s a convenient and effective solution for various external water needs.
Yes, the rainwater tank can be connected to a garden irrigation system. This is a common and desirable application for rainwater systems. The irrigation system can include automatic drip feeders and pop-up sprinklers, regulated by a timer box. When the timer activates the irrigation system, the submersible pump in the underground tank detects the drop in pressure, turns on, and supplies water until the timer switches off. The pump operates under pressure, similar to other household appliances. It’s an automatic process that provides water for garden irrigation. It’s important to note that if using drip feeder pipes, additional pressure reducing valves may be needed to ensure the system functions as intended.
Yes, surface water can be collected in a rainwater harvesting tank, but there are considerations to keep in mind. It is important to determine if the rainwater collected from the roof alone is sufficient for your needs. If it is, there is no need to collect surface water. However, if additional volume is required, surface water can be considered.
When collecting surface water, it is crucial to treat and filter it, as it may contain mixed fuels, oils, or other contaminants. This is especially important if the surface water comes from areas like car parks or driveways. Collecting water from pavement areas or back gardens might be safer as they are less likely to contain vehicle-related pollutants.
Before channeling surface water into your rainwater harvesting tank, carefully assess its source and potential contaminants. Consider the purpose of the water and the amount of rainwater you truly need to harvest. Generally, it is encouraged to rely on roof areas only unless additional volume is necessary.
Yes, rainwater harvesting can be a valuable resource during droughts. In a drought, when there is a prolonged lack of rainfall, any water collected through rainwater harvesting becomes an extra supply that would not have been available otherwise. It can help supplement water needs during these dry periods. So, yes, rainwater harvesting can indeed assist during droughts.
The overflow from a rainwater harvesting tank can be directed to different places depending on the situation. The two primary options are a soakaway or a storm drain. If the soil has good permeability and there is enough space available, it’s preferable to discharge to a soakaway. However, if the ground conditions are poor or there is no suitable percolation rate, the overflow can be directed to a storm drain.
Graf systems offer specific filters based on the discharge destination. For a soakaway, a basket filter is used to retain leaves and debris. For a storm drain or alternative option, a self-cleaning filter is used to wash the water over the top and prevent leaves and debris from entering the soakaway. The choice of filter depends on the specific discharge destination.
The type of filter you need for your rainwater harvesting system depends on your specific needs and usage. If you’re using the system for gardening purposes only, a basket filter is recommended for efficient filtration and capturing debris. For a household system with higher water demand, a self-cleaning filter is more suitable to ensure continuous filtration. If you’re discharging water into the ground through a soakaway, a basket filter is preferred to retain leaves and debris. The size of the filter is determined by the pipe diameter, which is based on the catchment area. Consider these factors when selecting a filter for your system.
When installing the tank, there are two types of backfill to consider: pea shingle and granular backfill. Pea shingle, with a size of 8 to 16 millimetres, is commonly used and provides good compaction without voids. In the UK, 10 to 20 millimetres is acceptable. Granular backfill is suitable if you have well-draining soil and offers more flexibility in the installation process. Another option is a lean dry mix concrete backfill, which is recommended for challenging soil conditions. The excavation size should allow for working room around the tank, typically 250 to 500 millimetres. If you need advice on available backfill materials in your area, we’re here to help. Stone is preferable, but concrete is also a suitable option if necessary.
During periods of no rainfall, if the rainwater tank runs out of water, there are options to ensure a continuous water supply. The system is designed to prevent running out of water, but if it does happen, there is a mains water top-up supply available. This can be achieved through a gravity-fed mains water supply to the underground tank, a direct mains water supply to a loft tank (in the case of a header tank installation), or a modern pump kiosk with a float switch. These mechanisms detect the water level and automatically redirect mains water to the appliances until the underground tank is refilled during the next rainfall event. So, even during periods without rainfall, there is a backup solution in place to provide water to the appliances.
Firefighter water tanks are mandatory for certain types of projects in the UK. These tanks are essential for providing access to water in case of a fire emergency. Whether it’s a school, supermarket, or hotel complex, there should always be a fire hydrant access point as part of the site’s risk assessment. GRAF offers their own firefighting tanks, which are marked and known to the fire service. Even smaller domestic projects may require an access point for fire engine top-up facilities. The presence of these tanks ensures that there is a readily available water supply for firefighting purposes. While the requirement for firefighter water tanks depends on the project and the availability of a mains water supply, it is important to consider them during the design phase to meet regulatory standards.
The float switch works in conjunction with a direct feed system to ensure a continuous water supply to the appliances. When the tank has sufficient rainwater, the float switch remains in a vertical position, signaling that rainwater can be supplied on demand. However, if the rainwater level in the tank decreases, the float switch drops, triggering a response. This response varies depending on the system setup, such as a wall-mounted pump kiosk or a submersible pump solution with a mains water top-up unit.
In either case, the float switch controls the automatic flow of rainwater or mains water to ensure a consistent water source for the appliances. It acts as a control mechanism, allowing the customer to always have water available for their needs.
To identify if a water outlet has a mains water or rainwater connection, there are specific labelling and colour codes to look for. Rainwater outlets should be labeled and marked with black and green colours. For underground pipes, it will typically be a black pipe with a green stripe. Outside taps should have a plaque indicating that it is a non-drinking water source, usually green with black text.
It’s important to note that most mains water taps won’t have any labelling. If there’s no label, it’s likely a mains water connection. However, it’s always a good idea to confirm with the owner or building authority to be sure. When ordering a rainwater harvesting system, there should be sticker kits or labelling packs available to mark the outlets correctly. If these are not provided, you can contact the manufacturer to obtain them. It’s essential to label outlets, especially if there are children living in the property, to prevent accidental consumption of rainwater.
Yes, it is possible to install a rainwater harvesting system underneath a driveway. With Graf tanks and many other systems available, they are designed to support light-duty traffic loads. It’s important to ensure adequate cover levels over the tank to distribute the load and upgrade the tank cover accordingly.
For light-duty traffic, a vehicle loading lid can be used, while for heavier loads such as HGVs, a specialist installation practice is required. This may involve recessing one of the lids and placing a suitable manhole cover and frame, such as a T400 or higher grade, over it. On domestic properties, installing for light-duty traffic is relatively straightforward. However, for larger construction sites, it may be necessary to grade the system and use a bespoke manhole cover.
Overall, it is feasible to install a rainwater harvesting system under a driveway, but the specific requirements will depend on the load capacity needed and the installation practices followed.
To learn more about rainwater harvesting and find answers to your questions, you can visit our website grafuk.co.uk. Our blog page contains various articles that cover topics such as what rainwater harvesting is, different types of systems (direct or indirect), and more. Additionally, we have a YouTube channel where you can watch videos showcasing how our systems work and gain a better understanding of their benefits and applications. Whether you’re interested in sizing the system, choosing between direct or indirect systems, or simply using rainwater for garden irrigation, our resources will provide you with valuable information to help you make informed decisions.
Looking in accordance with the British Standard regulation, you would use the harvested rainwater for toilets, washing machine, outside cleaning, and irrigation. These are the primary uses. You can further treat the water to disinfect it with carbon filters, UV and micro filters. By taking out any impurities in the water, you can reuse it for other possible appliances such as the dishwasher or showers.
Here in the UK, we have the technology to improve on making the water quality better. If we compare it to outside the UK, where they are not so advanced in the more rural locations of the world. Rainwater is most likely the cleanest source of water they can get a hold of, so in their case they will drink it.
This depends on the technical package you have. Most systems will run off an automatic pressure-sensitive pump, which will pump water on demand to the application by opening and closing of a valve. The pump will sense the opening of that valve and it will pump water on demand until the valve closes, then it will shut off.
With more advanced systems, we can supply a control panel to give you a bit more in-depth detail of what is going on in terms of the use of the rainwater versus how much mains water you are potentially saving. It can also detect the level of water in the ground tank as well as opening and controlling solenoid valves for automatic cleaning of the filters.
For standard systems, it would be the submersible pump options. Whereas with more advanced systems, you can have a lot more technology with the control system to get a better idea of how efficiently your system is working.
With control systems, whether this is a pump console or submersible pump, we would supply power to that 24 hours a day. But it is the operation of the pump, so it turns on via a float sensor built into the pump when the valve is opened. So, the pump is only running whenever you have water running to an outlet. The power is only consumed when the system is in operation, so it is an automatic process. Once the system is turned on, the pump will pump on demand and then will shut off once the valve is closed.
There are two types of filters commonly used in rainwater harvesting systems. If the tank discharges into the ground via a soakaway, a basket filter is typically used. Homeowners are advised to open the manhole cover, remove the basket filter, empty the debris into a compost bin, and then replace it back into the tank. It is generally recommended to clean the basket filter every two months, but the frequency may vary depending on the property’s location and surrounding trees.
For stainless steel self-cleaning filters, which are connected to a storm network rather than a soakaway, the buildup is not as long. It is usually recommended to clean these filters every six months. However, homeowners will gain an understanding of the specific cleaning frequency based on their system’s performance over time.
It is also recommended to visually check the filter once a month to ensure its proper functioning. This can be done by opening the manhole cover and inspecting the water levels and the cleanliness of the filter. If cleaning is required, the filter can be easily accessed and lifted using the handle on top.
Yes, you can use a rainwater harvesting system for agricultural purposes. Agriculture has significant water demands, including irrigation, livestock watering, vehicle cleaning, washdown, and even some refining processes. Rainwater harvesting provides a great opportunity for farmers to supplement their water needs and achieve substantial savings.
While domestic rainwater harvesting can save up to 50% of water usage, in agriculture, the savings can reach even higher, up to 80-90%. Considering the large amount of water used in agricultural operations compared to households, the potential water savings are highly significant. Implementing rainwater harvesting in agriculture is a beneficial and practical solution to meet water demands efficiently.
To determine the size of water butt you need, a good rule of thumb is to aim for at least a hundred days’ worth of water supply, which is a little over three months. To calculate this, consider the size of your watering can and how many times you water your garden each day. For example, if you use a 1-litre watering can and water your garden three times a day, you would need a 300-litre water butt to provide a hundred days’ worth of water.
It’s important to choose a container size that suits your needs. While rainwater harvesting can quickly fill a water butt with just one rainfall event, consider where you will place the container. If you prefer a discreet location, ensure you have enough space to accommodate the size and shape of the water butt. Additionally, think about whether you want a decorative style or a container that can be hidden away when not in use.
One popular option is the Slim Stone Wall tank, which holds 300 litres of water. Despite its slim design, it can fit in tight spaces, allowing you to capture a high yield of rainwater for garden use.
Yes, you can retrofit a rainwater harvesting system to an existing building. If you only plan to use the harvested rainwater for outside irrigation and cleaning, it’s a straightforward installation. You connect the rainwater tank to an outside tap or extraction point.
However, if you want to use the rainwater for appliances like toilets or washing machines, retrofitting is more complex. You need to consider preventing cross-contamination between rainwater and mains water. It’s possible to connect the rainwater system to an outside toilet or garage washing machine, isolating the mains water supply.
Rainwater harvesting systems prioritize the use of rainwater first, with a mains water backup supply activated through a flow sensor from the tank.
Even with a small tank, retrofitting can supplement approximately 25-30% of your mains water usage, providing significant environmental benefits and potentially reducing your mains water bill.
Rainwater is beneficial for plants compared to mains water. It contains natural nitrogen absorbed from the air, which enhances plant growth. In contrast, mains water is chemically treated and contains chlorine and minerals that may not be as good for plants. Rainwater, being closer to nature, provides plants with compounds that are beneficial for their development. So, when it comes to watering plants, rainwater is a better choice.
To collect rainwater cheaply, there are a few simple options. One way is to use a water butt, an aboveground tank available in different sizes and colors, costing around £25-£300. This allows you to store rainwater for years and use it for watering plants or outdoor cleaning with the help of a pump. Another option is to incorporate rainwater collection into sustainable urban drainage systems (SUDs) required for flood prevention in cities. By adding storage capacity to these systems, rainwater can be retained and reused to support green areas. Whether using a water butt or integrating with existing solutions like SUDs, collecting rainwater is an affordable and eco-friendly approach.
Using rainwater for showers can be a bit complicated. While some countries allow it with specific standards, in the UK, it’s generally advised to filter and purify the water before using it. Rainwater runoff from roofs can contain contaminants like moss, so it’s important to cleanse the water. Filtration systems can remove impurities, and UV purification can further enhance water quality. For uses like showering and sinks that involve direct contact with the skin, deionisation to remove minerals and disinfection are recommended. It’s achievable to use rainwater for showers, but upgrading a standard rainwater harvesting system in the UK ensures better water quality.
Wastewater treatment systems require regular maintenance, which can be divided into two areas: servicing and de-sludging. For domestic systems, we recommend an annual servicing visit by an engineer to check the treatment process and component health. Commercial systems may require a minimum of two visits per year due to their larger size and more components. Additional modules, such as phosphorus mitigation, may require three to four visits to ensure compliance with discharge parameters.
The de-sludging interval is determined by the size of the primary catchment chamber. Domestic systems typically require de-sludging every 12 months, while commercial systems may need it every six months or even more frequently. It’s important to conduct the servicing before de-sludging to assess the treatment plant’s performance accurately.
By maintaining a regular servicing schedule and adhering to de-sludging intervals, you can ensure optimal performance and longevity of your treatment plant.
Discolouration is to do with the introduction of impurities into the tank. So with the collection of rainwater off a roof, or potentially if you’re collecting rainwater off a surface, like a patio or pavement, you are channeling that water down into the collection device. Now, depending on how clean that surface is, you’re introducing impurities. It could just be dirt and grits. It could be oil if it’s coming off a car park. With the introduction of these impurities, you are going to discolour the water in the tank. The tank itself, the water that’s in there, should remain clean if the catchment area is clean. So it’s only by introduction of the catchment area that water will become discoloured in the tank.
There are two types of filters we would normally offer or see within the market of rainwater harvesting. We would normally use a basket filter if the tank were discharged into the ground via a soakaway. A basket filter will capture all the leaves and debris that runs in from the downpipes into this basket. The buildup of more solid debris in that basket will quickly accumulate. We advise the homeowner to open the manhole cover, lift the basket out and empty it into the compost bin. Replace it back into the tank, ready for the system process to continue. With a basket filter, we recommend anything for up to two months. It depends on where your house is found versus the number of trees, so the buildup on your property might be faster than potentially another homeowner.
If you are looking at one of the stainless-steel self-cleaning filters, these are designed for water to wash over the top and take leaves and debris out of the outflow. It is important with this filter that you connect it to a storm network and not into a soakaway. If it goes to a soakaway, those leaves and debris would block the soakaway every time. This is something to pay attention to. But with the self-cleaning filter, the buildup is not so often and recommend checking every 6 months. But once the customer gets an understanding of how long their system has been in place, they will get an idea of how often it needs to be done.
However, we do recommend a visual check once a month of the filter to be taken out, lifted. The cover is relatively easy to lift off. If you’ve got one of the pedestrians covers, it opens with a torque wrench and then you are able to carry out a visual inspection into the top of the tank. Check water levels and the cleanliness of the filter, if it does need to be washed down, it can be easily reached via the handle on the top of the filter to be taken out and lifted and cleaned.
Rainwater harvesting has different meanings globally. In areas without access to mains water, rainwater is a vital resource. In the UK, where mains water is available, rainwater can be used to supplement our water consumption as urban development strains existing systems.
Rainwater harvesting can substitute up to 25% of mains water usage, reducing demand and associated costs. It also helps with mitigating droughts, managing floods, and reducing carbon footprint. Water companies utilize significant energy to treat mains water, resulting in a large carbon footprint. Utilizing rainwater locally can make a substantial difference and contribute to environmental protection.
Rainwater harvesting is a step towards sustainability. While government goals are set for the future, it is important to remember that local actions matter. Each individual’s choice to use rainwater instead of relying solely on mains water has an impact.
Addressing the strain on existing water systems and protecting the environment is crucial. Rainwater harvesting and wastewater treatment solutions can have a positive global impact and contribute to a more sustainable future.
Rainwater harvesting has several environmental impacts that are worth noting. Firstly, it helps reduce the speed and volume of stormwater runoff, which aids in flood prevention and minimizes erosion. This is particularly important in urban areas with high levels of pavement and concrete. Secondly, rainwater harvesting is beneficial during droughts, as it provides a local water source that eases the strain on reservoirs and supports ecosystems. Thirdly, implementing rainwater harvesting systems in urban areas creates green spaces, promoting habitats for various species and contributing to biodiversity. Additionally, rainwater harvesting significantly reduces mains water demand, resulting in a substantial decrease in the carbon footprint associated with water treatment and supply. By substituting rainwater for mains water, both the manufacturing process and the energy consumption of water firms are reduced. Overall, rainwater harvesting has a positive environmental impact by conserving water resources, mitigating flooding, supporting ecosystems, and reducing carbon emissions.
Water neutrality is a new legislation introduced by Natural England to ensure that new buildings do not strain existing water resources. The goal is to minimise the impact on the environment and maintain water consumption levels from before the development. This involves reducing water usage, reusing water through methods like rainwater harvesting and water recycling, and offsetting by supporting other water-efficient projects. Reduction can be achieved through mindful water usage and the implementation of water-efficient appliances. Reuse involves capturing rainwater or treating wastewater for irrigation purposes. Offset refers to supporting external projects that reduce water demand. Water neutrality aims to protect water resources and promote sustainable development for future generations.
Sewage Treatment Plants, Cesspools, and Septic Tanks FAQs: Your Comprehensive Guide
Welcome to our FAQs portal, where you’ll find answers to all your questions about sewage treatment plants, cesspools, and septic tanks. Whether you’re a homeowner, an installer , or simply curious about these systems, we’ve got you covered. Discover valuable information, expert advice, and solutions to common issues related to wastewater management. Explore our comprehensive guide today and gain a deeper understanding of how these systems work, their maintenance requirements, environmental impact, and more. Get informed and make well-informed decisions for a cleaner and healthier future.
When it comes to waste from a septic tank, there are two paths. The treated effluent water is discharged into the ground through a drainage field. This is the water at the top of the tank. The solid waste, or sludge, remains in the tank and needs to be emptied by a de-sludging company. They will take it to a municipal treatment works where it is further treated. Most wastewater that is connected to the sewage network follows this route. However, it’s important to note that recent changes to regulations prohibit septic tank discharge into water courses. In such cases, options include implementing a drainage field for ground discharge or upgrading to a wastewater treatment plant, which still complies with regulations and allows discharge to water courses with improved effluent quality.
Maintaining a sewage treatment plant involves two main aspects. Firstly, it’s important to adhere to the desludging schedule provided by the manufacturer. This means arranging for the tank to be emptied at the recommended interval, which can range from six months to two years depending on the system. This ensures the continuous operation and effectiveness of the treatment process.
Secondly, engaging the services of a qualified engineer to regularly service the system is crucial. During the service, the engineer will assess the system’s performance, including the quality of effluent discharge and the functioning of components. It’s essential to understand that a treatment plant supports the biological process by increasing oxygen levels, which is vital for the system’s success.
Having an understanding of how the treatment plant operates is valuable for homeowners, as it enables them to take an active role in maintaining their system. For commercial applications, maintenance is typically handled by the responsible authority. Regardless of the setting, comprehending the biological process and its purpose in promoting water quality is important to protect the environment.
By following these maintenance practices and ensuring an adequate oxygen supply, sewage treatment plants can effectively treat wastewater and discharge high-quality effluent to safeguard the environment.
There are three ways water can be moved out of a tank. For septic tanks, gravity is commonly used, where the water level remains static. In systems like our Graf treatment plants, we use airlifts to lift the water out of the tank, similar to pumping. This allows for a lift to the same level as the inflow or even higher for raised discharge.
The second option is an electronic pump. This can be incorporated into the septic tank or treatment plant itself, using a pump on a float switch inside the tank or an external pump chamber. A pump is necessary when the water needs to be lifted to a higher location, such as a garden or a car park.
While pump solutions are available, manufacturers generally try to avoid them due to the reliance on electronic elements. Power cuts can cause issues with pump operation. It is recommended to minimise the use of electronic pumping elements when possible. For treatment plants with pump solutions, external pump stations are preferable for easier access, maintenance, and servicing.
Considering the specific needs and circumstances, customers should carefully weigh the options and choose the most suitable method for their situation.
In general, septic tanks and treatment plants are designed to be underground, providing natural insulation from frost. The soil acts as a protective layer to prevent the water in the tank from freezing. When wastewater is discharged from the property, it is relatively warm compared to freezing temperatures in the ground. This helps maintain a higher water temperature within the treatment plant.
For the biological processes in the tank to work effectively, the water temperature needs to be above 12 degrees Celsius. If the water level is nearing freezing, it indicates a serious problem with the biological process. In such cases, insulation options should be considered to protect the tank.
Customers may also want to consider shallow dig septic tanks, which are closer to ground level. However, this can make the tank more susceptible to colder temperatures. Nevertheless, in the UK, it is unlikely that temperatures will drop low enough for the water inside the tank to freeze. If customers have concerns, opting for a deeper installation can provide added assurance.
The purpose of a sewage treatment plant is to protect the environment by improving the conditions for bacteria inside the tank. These bacteria break down the incoming wastewater, resulting in high-quality effluent that can be safely discharged. The main goal is to ensure the effective treatment of wastewater and minimise its impact on the environment.
It’s important to be mindful of what you flush down the toilet if you have a wastewater tank. Avoid pouring fats, oils, and greases down the sink as they can cause issues. Use cleaning products in moderation, especially avoiding chlorine-based ones. Certain items like wet wipes, cotton buds, sanitary towels, razor blades, and non-biodegradable materials should not be flushed. Hair can also wrap around components and hinder the system’s operation. Even if it’s not the homeowner’s doing, such as during renovations, substances like paint and thinners should be kept away from the treatment plant. Being responsible with what goes into the tank helps maintain its effectiveness.
Bleach and detergents can be used with a septic tank, but it’s important to use them in moderation. Regular household use is generally fine, but excessive use or introducing aggressive cleaning products from holiday home cleaning can disrupt the tank’s biological process. Consistency is key, and using washing detergents that are more friendly to the tank’s bacteria is recommended. It’s best to avoid chlorine-based products as they can be harsh on the tank’s ecosystem.
When it comes to tank positioning, it’s important to consider the guidelines in building regulations. Ideally, the tank should be installed seven meters away from the property. However, if that’s not possible, you can find the best alternative. Keep in mind the access for the de-sludging vehicle that will empty the tank. They typically use 30-meter-long suction lines. While it’s possible to install a tank at the front of your property, it’s important to be mindful of potential odours if the tank isn’t functioning properly. Placing it near windows or patios may result in noticeable smells. Consider the optimal position for your project, whether it’s at the front or elsewhere, and make sure it’s convenient for the de-sludging process.
To clean a wastewater tank, a desludging company needs access to the tank. They can either use a shaft or open the main manhole cover. The company will empty the tank based on the manufacturer’s guidelines and the sludge storage volume. They will suction the waste and transport it to a municipal treatment plant for offsite treatment.
A septic tank is a holding tank for wastewater. It separates the sludge through baffle walls and allows the settled sludge to remain in different chambers. The liquid waste is discharged through an outlet into a drainage field, following the code of practice. Upgrading from a septic tank that discharges into a watercourse is recommended. The treatment process primarily involves the settlement of sludge and extracting water while preventing solids and scum from reaching the drainage field. This helps maintain the drainage field’s lifespan and keeps the sludge inside the tank.
To calculate the size of a septic tank, start with a minimum base volume of 2,000 liters. Then, consider the source of waste and refer to the Flows and Loads guide from British Water. It provides the liters discharged per person per day for different types of properties. For example, a standard residential dwelling may have 150 liters per person per day. Multiply this by the population to get the daily volume. Add it to the base volume to determine the required storage volume.
For instance, a five-person household would be 5 x 150 = 750 liters per day. Adding this to the base volume of 2,000 liters gives a required storage volume of 2,750 liters. It’s important to choose a tank with a volume equal to or larger than this.
Consider the specific requirements of your property. For example, in an office building with 10 full-time staff members, if each person generates 90 liters per day, the calculation would be 10 x 90 = 900 liters per day. Adding this to the base volume gives a required storage volume of 2,900 liters.
Keep in mind that the desludging interval will depend on the tank manufacturer and may vary. It’s essential to gather this information from the customer before making a decision.
Determining the level of sludge in your tank depends on whether you have a septic tank or a wastewater treatment plant. For septic tanks, you can use a simple method. Insert a stick into the tank, lift it up, and measure the marking on the stick to determine the sludge level. This can be compared to the recommended maximum level provided by the manufacturer.
For wastewater treatment plants, a Sludge Volume 30 (SV30) test is commonly performed. This involves taking a sample of sludge from the plant and allowing it to settle in a measuring cylinder for 30 minutes. The volume of settled sludge at the bottom compared to the liquid layer on top indicates the sludge percentage in the tank.
For accurate results, it’s recommended to have a professional service provider perform the SV30 test. They can also carry out other checks on the system components during the same visit. Performing the SV30 test at the beginning of the service allows the settling process to occur while other checks are conducted.
It’s important to know the sludge volume in your tank to plan for necessary maintenance, such as tank emptying. Consulting the manufacturer’s guidelines and working with a professional servicing company can help you determine the sludge volume and maintain your system effectively.
Septic tanks are like old technology. You will see septic tanks built from many years ago. That is all dependent on what the tank is made from. Some older generation buildings, they have got brick tanks and those tanks will start to degrade over time. If you were to pump them out, you will just see that the surface walls of the tank starting to wear over time. More recently, we are looking at plastic tanks but still can get some concrete tanks.
Lifetimes on these tanks could range based on the quality of the plastic like reinforced plastic or HDP, which we use. It could be anything from 15 to 25 years, and then service life could go beyond that. There is not reason why it can’t go beyond if it is installed as per the manufacturer’s installation instructions. However, there are some limiting factors, especially in the UK in terms of ground conditions. You might need to ask the manufacturer’s advice if you have got challenging circumstances you need to overcome. The surface like can be anything from up to 25 years on a plastic tank.
Yes, a sewage treatment plant requires a discharge point for the treated water. Traditionally, septic tanks would use a soakaway or drainage field, and treatment plants can also utilise these options. However, treatment plants offer the additional possibility of discharging into a water course. It’s important to consider the permitted flow limits when discharging to a water course and obtain the necessary permits if exceeding those limits. Regardless of project size, discharge options need to be carefully evaluated when using treatment plants.
A treatment plant itself does not typically cause odour issues. However, sudden changes in the system’s environment, such as increased flows or the use of different cleaning products, can lead to smells generated by the treatment process. To prevent odours from entering the house, it’s important to have proper ventilation and water traps installed in the discharge pipes of sinks and showers. Consistency in the use of cleaning products and maintaining a stable environment in the treatment plant helps keep the biological process balanced and odour-free. Implementing effective ventilation systems and directing foul air away from living areas is essential. Proper design and installation of the wastewater treatment system can prevent odour-related disturbances for homeowners.
It is generally preferred to have a septic tank installed in a way that allows for gravity discharge rather than uphill installation. When a septic tank needs to be installed uphill, a pump station or chamber is required to push the water uphill. This adds additional cost and maintenance as the mechanical pump in the chamber needs to be serviced and monitored. If the pump fails, there can be a backup of foul water. Most manufacturers offer pumping station options, but it’s important to consider the ongoing maintenance and servicing requirements.
It is advisable to keep rainwater away from septic tanks and foul water treatment plants. Rainwater can disrupt the biological process within these systems. As the future trend is shifting towards treatment plants, it is important to divert rainwater from foul water discharge. Connecting rainwater to septic tanks can cause flooding during heavy rainfall. It is recommended to size tanks properly and consider expected foul water flows and storm events. Keeping rainwater and stormwater separate from foul water discharge is good practice to avoid potential issues.
The maintenance schedule for treatment plants can vary based on whether it’s a domestic or commercial system. For domestic systems, we recommend that homeowners have a general understanding of how the system works and perform regular checks. It’s also advisable to have a professional service provider inspect the system once a year to ensure it’s working properly and the effluent quality meets standards.
Commercial systems, on the other hand, typically require ongoing maintenance and have designated personnel responsible for their care. These individuals should have a good understanding of the system, its operation, and troubleshooting procedures. Commercial treatment plants usually undergo maintenance twice a year, and if additional modules are present for phosphorus removal, maintenance may be required more frequently, potentially three to four times a year.
Maintenance also includes the desludging of the tank, which has a designated volume specified in the technical data sheets. The interval for desludging can range from 6 to 12 months, depending on factors such as the number of people served and the size of the treatment plant.
It’s important to consider these maintenance requirements to ensure the optimal performance and longevity of the treatment plant.
Our treatment plants operate using a sequence batch reactor (SBR) technology, which sets them apart from competitor systems. While power is supplied to the treatment plant continuously, the control technology regulates its operation. Our systems follow an interval-based biological process, where power is directed to the compressor and valves at specific times throughout the day.
In total, the compressor typically runs for about 12 hours a day, unlike competitor systems that may run continuously. Although domestic compressors consume minimal energy, those concerned about energy consumption may find the SBR option appealing, as it runs the system for less time, potentially resulting in energy savings.
It’s important to note that SBR systems utilise airlifts and intermittent aeration for different stages of the treatment process, such as organic material breakdown and nitrification. Therefore, it’s crucial to maintain continuous operation to ensure the effectiveness of the biological process. Turning off the system during the night is not recommended.
When considering the installation of a wastewater treatment system, it’s advisable to place the compressor in an area where noise and vibration won’t cause disturbance to you or your neighbours. Being mindful of these factors will contribute to a smooth implementation of the system.
With Graf systems, we have a control panel that supports the operation of the system. If there is a fault or warning, a red light and possibly an audible sound will indicate the issue. For the biological process, it’s important to only introduce domestic waste and water into the tank. When non-biodegradable substances or high volumes of bleach are added or there are inconsistent fluctuations in waste input, it can disrupt the biological process. This disruption can lead to odours generated by bacteria. Smells coming from the system indicate that something may be wrong underground. Good treatment performance should not produce any smells.
For holiday homes or properties with irregular usage, installing a ventilation system can help redirect any foul water smells away from the property. It’s crucial to be mindful of evaporating water from sinks and showers in unoccupied periods, as this can lead to odours flowing back into the property. However, if the treatment plant is functioning well, there should be no cause for concern. Smell is often the initial indicator of any issues with the vital process or control panel operation.
Venting a septic tank is essential to ensure proper airflow and prevent potential odours. It involves incorporating both a low level vent and a high level vent in the system.
The low level vent is placed after the septic tank, treatment plant, or cesspool. It allows air to be drawn in from the surrounding area. The high level vent is located at the inflow point and serves as an outlet for the air.
Depending on the site conditions, you may have spinning cowls, one-way valves, or fans integrated into the ventilation system to promote airflow. In areas with good wind flow, natural ventilation is often sufficient. However, in enclosed spaces, additional measures may be needed to encourage airflow.
For modern developments with internal soil stacks, it’s beneficial to include an external high level vent that extends above the roof or another suitable location, such as a shed or garage.
By incorporating both low level and high level vents, a septic tank can be properly vented, allowing for the flow of air and preventing any potential odour issues.
When it comes to discharging into a watercourse, it’s important to refer to the code of practice, specifically 12566-3, which applies to wastewater treatments. For our wastewater treatment systems, if the volume of treated water being discharged is less than five cubic meters, it can go directly into a watercourse without permits. However, if the volume exceeds this, a discharge permit is required to assess the potential environmental impact.
The code of practice sets guidelines for certain effluent parameters, including BOD (biochemical oxygen demand), suspended solids, and ammonia. The standard rule is to achieve 20 milligrams per litre for BOD, 30 milligrams per litre for suspended solids, and 20 milligrams per litre for ammonia. These parameters may vary depending on factors such as protected areas or specific project requirements.
Some projects may have stricter effluent parameters or additional treatment requirements, such as nitrogen and phosphorus removal. In such cases, additional modules can be added to the treatment system to target and reduce these levels further. However, for most cases, meeting the 20, 30, 20 parameters and discharging less than five cubic meters per day is sufficient for direct discharge into a watercourse.
When you purchase a treatment plant system from us, the supply includes two separate pallets. The first pallet contains the tank itself, fully assembled and ready for installation. It includes components such as the diffuser, airlift, sump, and chamber. The second pallet contains accessories and controls for the system. This includes lids, air hoses for the airlift and diffuser, as well as the control panel and compressor. For advanced systems, additional components like pumps, dosing equipment, and remote modems are included on the accessory pallet. We also offer housing cabinets for both internal and external installations.
The running costs of the GRAF One2Clean sewage treatment system are generally very low. The system utilizes sequence batch reactors (SBR) and runs the compressor for only 8 to 12 hours a day, compared to other systems that run 24/7. This reduces energy consumption by up to 50% or more. The exact cost of running the system will depend on the size of the treatment plant and the homeowner’s electricity rates. On average, for a 5-person system, it is estimated to be around 46 kWh per person per year, which is relatively minimal. For specific cost calculations, further information from the customer is required. Please reach out to us with any direct questions about running costs.
The likely failures of a wastewater treatment system are typically related to electrical issues and improper understanding or care of the system. It’s important to remember that the treatment system relies on a working biological process, so it’s crucial to only allow biodegradable items into the tank and avoid introducing plastics, rubber, cans, and excessive amounts of cleaning products that can disrupt the biological process. Achieving a balance in the tank is essential for optimal performance.
The system’s components will also experience wear over time. Compressors, such as diaphragm, piston, or rotary vane compressors, have specific maintenance requirements outlined in the installation instructions. This may include regular cleaning or replacement of air filters and blades. It’s recommended to consult the service manual provided by the manufacturer for a better understanding of the maintenance procedures.
If you have concerns or want to learn more about your system, it’s advisable to seek the assistance of a competent service engineer who can provide maintenance services and offer on-site advice. At Graf, we offer flexible options for sending engineers to help you understand and optimise your system’s performance.
The benefits of using Graf systems over competitor systems are centered around adaptability and control. The control panel in Graf systems allows for flexible adjustment of oxygen levels within the tank, optimising the breakdown of organic material and enabling effective treatment of nitrogen compounds. This results in a higher quality discharge. Compared to other systems that run compressors 24/7, Graf systems offer greater control and targeted treatment.
Installation is also more convenient with Graf systems. Instead of requiring concrete backfill, a gravel base can be used, providing flexibility and saving time during installation. Additionally, the absence of moving components within the underground tank simplifies servicing and maintenance. The controls and software are located separately, allowing easy access for system checks and troubleshooting without the need to enter the tank.
In case of any issues, the control panel and compressor provide a clear indication of the system’s performance, minimising the need to enter the tank for troubleshooting purposes.
If you need help sizing your wastewater treatment plant requirements and you’re interested in a GRAF system, simply contact us. You can start by downloading the Flows and Loads guide from the British Water website to get an understanding of the parameters involved. Then, reach out to us, and we’ll guide you through the process, discussing your project requirements. Together, we’ll determine the appropriate system size for your needs. Once you’re satisfied, we can design and implement the system accordingly. So, if you want a GRAF treatment plant and assistance with sizing, give us a call. We’ll be there to help you every step of the way.
Wastewater treatment systems require regular maintenance, which can be divided into two areas: servicing and de-sludging. For domestic systems, we recommend an annual servicing visit by an engineer to check the treatment process and component health. Commercial systems may require a minimum of two visits per year due to their larger size and more components. Additional modules, such as phosphorus mitigation, may require three to four visits to ensure compliance with discharge parameters.
The de-sludging interval is determined by the size of the primary catchment chamber. Domestic systems typically require de-sludging every 12 months, while commercial systems may need it every six months or even more frequently. It’s important to conduct the servicing before de-sludging to assess the treatment plant’s performance accurately.
By maintaining a regular servicing schedule and adhering to de-sludging intervals, you can ensure optimal performance and longevity of your treatment plant.
The water discharged from a wastewater treatment plant is not drinkable, despite some claims in the industry. However, the water is generally very clean with only slight coloration due to suspended solids. The treatment process aims to meet quality parameters set by regulatory standards. These include limits for BOD (biological oxygen demand), suspended solids, and ammonia. Most treatment plants exceed these standards. It’s important to note that pathogens and microorganisms may still be present in the water. Future technologies like disinfection with UV or chlorine may further improve water quality, potentially allowing for reuse in gardens. However, there is currently no certification in the UK for drinking treated wastewater. So, while the water is of high quality, it is not suitable for drinking.
Treatment plants and septic tanks generally don’t produce smells if they are working properly. To maintain a good environment for the bacteria inside the tank, it’s important to avoid introducing non-biodegradable items like wet wipes and plastic. Sudden changes in the tank’s conditions, such as emptying the tank, can also cause temporary smells, but ventilation systems can help disperse them. It’s advisable to avoid sudden changes in chemical usage, like using excessive bleach or doing multiple loads of laundry in a short period, as this can disrupt the bacteria’s environment and lead to odours. Proper ventilation and spacing out activities that may affect the tank’s conditions can help minimise or eliminate smells.
For smaller systems, a 220-240V supply with a 13 amp main socket is typically needed. It’s recommended to have a dedicated supply from the fuse board for easier maintenance. Commercial applications may require three-phase power, which requires an electrician to handle the connections. We design control cabinets based on specific site requirements for commercial setups. However, for residential applications, a simple mains socket with a 13 amp capacity is sufficient for the system.
For domestic applications, it’s generally recommended to leave the system running even when going on holiday. The energy consumption is low, similar to a light bulb, and keeping the system working maintains its optimal performance. However, for larger commercial systems, a holiday mode can be beneficial to reduce energy usage and maintenance requirements. In such cases, the system control panel allows for selecting holiday mode to adjust compressor runtime, and it can be restored upon return.
If the homeowners will individually own the sewage treatment systems, it is generally recommended to install separate systems for each property. This helps to avoid potential conflicts and maintains good relationships between neighbours. Each homeowner will be responsible for the maintenance and servicing of their own system.
However, if the local council will handle the maintenance and servicing of the systems, it may be more feasible to install a larger treatment plant that can serve multiple properties. In this case, the council will take care of the system’s upkeep, servicing, and emptying. This helps prevent any disagreements among neighbours regarding the cost and responsibility of maintenance.
It’s worth noting that local authorities often encourage the installation of larger systems when feasible. Homeowners should consider these factors when deciding whether to install separate systems or a shared treatment plant.
To determine the size of a wastewater treatment system, you can refer to the Flows and Loads guide available on the British Water website. This guide provides information on different sources of waste and their corresponding flow rates, organic material (BOD) concentration, and ammonia levels. Based on these parameters, you select a system that can handle the highest concentration among the three.
For small domestic applications, you can consider the number of bedrooms in the property and add a certain number to determine the system size. For larger projects or commercial applications, it’s best to seek advice from experienced professionals who can assist in selecting the appropriate system size.
Manufacturers are familiar with the Flows and Loads guide and can provide guidance and support in determining the right system size for your specific needs.
When considering the need for an external cabinet for your wastewater treatment system, there are a few factors to consider. Firstly, there is usually a recommended distance between the control panel and compressor and the underground tank, typically within 20 meters, to ensure optimal airflow for system operation.
An external cabinet provides several benefits. It allows you to locate the control cabinet in a more convenient or suitable location. Additionally, it helps reduce the sound and vibration generated by the working compressor, improving overall system comfort.
Furthermore, it is recommended to have your wastewater treatment system serviced and maintained regularly. Having an external cabinet provides easier accessibility for maintenance and servicing by engineers.
Considering these factors, an external cabinet can be beneficial for optimising system performance, convenience, and maintenance.
Determining when a septic tank needs to be emptied can be done in a few ways. First, you can check the designed storage level provided by the manufacturer and consider the tank’s volume and the number of people using it. If the tank is designed for more occupants than you have, it will likely last longer before needing to be emptied. Typically, septic tanks can last anywhere from six months to a year before requiring pumping.
For a more accurate measurement, sludge level pipettes can be used. These dipsticks can gauge the amount of sludge volume in the tank, and the manufacturer will provide the maximum volume before it needs to be discharged. However, this measurement is often carried out by a service engineer, especially for treatment plants.
While septic tanks require less monitoring, it’s still important to consider the sludge levels and the recommended frequency for emptying to ensure proper maintenance.
The purpose of a treatment plant is to reduce the concentration of ammonia in waste water, rather than producing ammonia. However, in certain cases, if you want to extract ammonia for other applications, it would need to be done at the source. For example, in a commercial or domestic building with urinals, urine can be collected separately and taken off-site for alternative use. But generally, the goal of a treatment plant is to minimise the ammonia concentration in the tank to minimise its impact when discharged into the environment.
The main difference between our one-screen system and our advanced wastewater treatment systems lies in the level of technology and targeted treatment they offer. The one-screen system is a standardised option that effectively breaks down components like BOD, suspended solids, and ammonia according to industry guidelines. It is designed to deliver high-quality effluent for domestic applications.
On the other hand, our advanced systems, such as the Klaro systems, utilise more sophisticated technology. These systems incorporate features like dosing pumps, chlorine reaction chambers, and UV treatments, allowing for targeted treatment of specific parameters. They are capable of achieving exceptional effluent quality and are particularly useful in projects that require nitrogen and phosphorus reduction.
In summary, the one-screen system is a reliable choice for domestic needs, while our advanced systems provide enhanced control and customisation to meet specific customer requirements.
In general, it’s recommended to install a sewage treatment plant at least seven meters away from a property. This helps prevent any potential odor issues and ensures the system functions properly. However, not everyone has enough space for this distance or access to a suitable drainage field located 15 meters away. In such cases, it’s important to consult with the building authority responsible for approving the project to find the best possible solution that meets the regulations and requirements of the specific situation. Working together, a compromise can be reached to ensure an appropriate installation.
To determine if your septic tank is full, it’s best to take a proactive approach. Find out the size of your tank and consult the manufacturer’s guidelines on storage capacity, which can vary based on tank size and usage. Another method is to lift the tank cover and use a stick to measure the amount of solid waste present. This gives an accurate assessment of tank fullness. Reactive indicators of a full tank include foul odors emanating from the tank and potential backups in drains. Additionally, if your lawn is unusually lush near the drainage field, it may suggest an excess of nutrients, but it’s worth investigating if the system is backed up. It’s important to be mindful of both proactive and reactive signs to understand the status of your septic tank.
The frequency of emptying a sewage treatment plant is typically recommended by the manufacturer. For domestic systems serving a single dwelling, it is often advised to have the system emptied once a year. It is good practice to leave some activated sludge in the tank during emptying to maintain the performance of the bacteria. The size of the system and the number of people using it should also be considered. Systems are usually oversized, providing a buffer and potential for longer intervals between emptying if there is low loading. Additional factors to consider are whether homeowners are using feeders or reducers to improve performance and reduce sludge accumulation. Feeders introduce bacteria-enhancing substances, while reducers help maintain an optimal sludge level of around 40 to 60%. The use of such products can extend the time between emptying. Commercial systems may require more frequent emptying, typically two to four times a year, depending on the application and waste volume.
When it comes to sewage treatment plant discharge, the quality of water is better compared to septic tanks. However, there may still be some biological processes and microbes escaping, which can impact the environment. According to the general binding rules, the discharge should go into the ground or a flowing water course to prevent nutrient retention on the site. The allowed discharge volumes are up to 2 cubic meters per day for underground discharge and 5 cubic meters per day for watercourse discharge, based on population size. If the discharge exceeds these volumes, a permit is required. The permit allows different discharge options, including the possibility of discharging into a pond under specific conditions. To obtain a permit, individuals should contact the local Environment Agency, which will provide guidelines and requirements for the discharge, including the desired quality of effluent. It is important to adhere to the general binding rules, and any exceptions will require a permit for discharge.
Cesspools and septic tanks are both used to collect and treat foul water runoff, but they have significant differences.
A cesspool retains all the liquid waste, including greywater and blackwater, in a tank. When it becomes full, it must be emptied by a tanker. Cesspools require suitable conditions for installation, especially in areas with high groundwater. They need to be sized according to the number of people using them, and they require frequent emptying.
On the other hand, a septic tank is more advanced. It has dividing walls and an outflow. It retains solid waste while allowing liquid waste to discharge into a drainage field, where it undergoes additional treatment as it percolates into the ground. Septic tanks require good soil for percolation and have volume restrictions for domestic use. They need less frequent emptying compared to cesspools.
Septic tanks have a slight environmental impact due to discharging into the environment, but with a properly sized drainage solution, the impact can be reduced. The sludge waste from septic tanks is typically taken to a foul water treatment plant, incurring costs for homeowners. Cesspools have a larger volume capacity and require more frequent emptying, making them less favorable compared to septic tanks.
Ideally, wastewater treatment plants should be considered first, followed by septic tanks. Connecting to the mains water network is the best solution if available. Cesspools are generally used as a last resort.
To determine if a wastewater treatment system is operating correctly, homeowners should have a general understanding of how their specific system works. This knowledge helps identify any issues that may arise. For example, if there are strong odors or problems with the drainage system, it could indicate a full sludge tank or other issues.
Performing daily checks, such as monitoring the system control panel, is essential for homeowners. Additionally, scheduling regular servicing by a knowledgeable engineer is recommended. Different treatment plants have variations, but understanding the working components and knowing what to look for is crucial.
During a service, key parameters like ammonia, BOD, and suspended solids are examined. Additional tests for phosphate concentration, nitrogen, and BOD can be done if required for environmentally sensitive areas. Checking system operation, back pressure on compressors, diffusers, and sludge levels are also part of a comprehensive service.
For GRAF system users, contacting GRAF or their network of service providers is the best option. GRAF offers onsite training and can connect homeowners with qualified service providers throughout the UK to ensure proper system maintenance.
When a sewage treatment plant is overloaded, there are immediate and long-term problems. Treatment systems have a buffer to handle additional short-term loads, but beyond that, issues arise. Smells from the system and compromised treatment performance are immediate signs that something is wrong.
Long-term overloading can lead to problems with drainage solutions, whether it’s going to the ground or a watercourse. This has a significant environmental impact and can result in costly repairs for homeowners. Discharging through a watercourse without proper treatment can even lead to penalty fines.
To avoid these problems, it’s crucial to ensure that the system is sized correctly from the start. Proper sizing and adherence to manufacturer’s recommendations are essential to protect the environment effectively.
Cleaning a septic tank is a crucial task to maintain its functionality and protect the environment. When a septic tank becomes full, it can cause blockages and harm the drainage system. To clean a septic tank, it’s best to hire a specialised company with the necessary equipment. They will empty the tank, removing the water and sludge. After cleaning, it’s advisable to refill the tank with mains water to maintain stability and prevent external pressures. This cleaning process ensures the longevity and effectiveness of the septic tank system.
Let’s clarify the term “septic tank” first. A septic tank is a non-electrical system that separates incoming and outgoing waste through split chambers. The treatment occurs within the tank using dividing walls, and the liquid waste is then discharged into a drainage field for further treatment as it percolates through the ground. Generally, septic tanks do not require electricity.
However, when we mention the use of electricity, we are referring to wastewater treatment systems or package treatment plants. These systems incorporate biological processes to optimise the breakdown of foul water before it is discharged into the environment. So, septic tanks do not use electricity, but wastewater treatment systems do.
There are a few important considerations for maintaining a sewage treatment system:
- Be mindful of what you flush down the toilet. Non-biodegradable items like plastics, metals, rubbers, wipes, and cigarette butts can cause blockages in the system.
- Keep the tank regularly emptied to prevent it from becoming too full. An overflowing tank can block incoming and outgoing pipelines.
- When discharging treated water into the environment, be aware of potential flooding in watercourses or high groundwater levels. These conditions can lead to blockages. Prior research on soil conditions is crucial to ensure the system can handle different weather conditions throughout the year.
By avoiding non-biodegradable items, maintaining the tank, and considering environmental factors, you can prevent blockages and maintain an effective sewage treatment system.
A sewage treatment plant aims to improve the breakdown of foul water that enters the tank. Bacteria are introduced into the tank through the black water from toilets, and they break down the water. To enhance bacteria’s efficiency, different types of treatment plants use various methods.
Most treatment plants have a dividing wall that separates the chambers and retains solids in the tank. Water is moved between chambers using pumps or airlifters. Some plants use plastic material called media to increase the surface area for bacteria growth. Filters separate waste and remove impurities. Aeration, the most important process, introduces oxygen into the water, creating a better environment for bacteria to break down the water effectively.
The goal is to achieve high-quality treatment. Each sewage treatment plant improves the living environment, separates waste, and retains it within the tank. Bacteria need food from incoming blackwater and greywater, and we provide oxygen to help them work efficiently.
The treatment process breaks down various compounds present in the foul water, reducing their levels. Treatment efficiency is a measure of how effective a wastewater treatment system is. Different technologies and system types determine how the treatment plant operates.
GRAF systems use dividing walls and aeration processes. Other manufacturers may employ additional components like media, filters, and pumps to optimise treatment performance and achieve desired water quality.
Nutrient neutrality aims to reduce the runoff of domestic foul water from developments to protect the environment. It involves reducing the nutrient runoff on-site and offsetting it through off-site measures. Incorporating an onsite wastewater treatment plant is an effective way to reduce nutrient runoff. However, additional measures are often needed to offset the remaining impact. This can include purchasing land for forestry growth or upgrading other systems that discharge into the same water network. Nutrient neutrality is crucial for preventing algal blooms and preserving aquatic ecosystems. It is a response to the increasing awareness of the environmental impacts caused by nutrient runoff from human activities. Achieving nutrient neutrality requires a combination of reduction and offsetting efforts, such as improving treatment plant efficiency and implementing tertiary treatments like wetlands or reed beds.
If you need help sizing your wastewater treatment plant requirements and are interested in a GRAF system, simply contact us. You can also refer to the British Water website and download their Flows and Loads guide version 4 for more information. Once you have an understanding of your needs, we can discuss your project requirements and guide you towards the right system size. We’ll work together to design and implement the system that suits your needs.
Stormwater Attenuation and Soakaway Tanks: Effective Solutions for Flood Prevention
Welcome to our FAQs portal, dedicated to stormwater attenuation and soakaway tanks—key components in flood prevention and water management systems. Discover how these tanks play a vital role in controlling stormwater runoff, reducing the risk of flooding, and maintaining sustainable drainage systems. Gain a deeper understanding of their design, installation, and maintenance, as well as the environmental benefits they offer. Whether you’re a developer, engineer, or homeowner, this guide will provide you with valuable insights and practical answers to your questions about stormwater attenuation and soakaway tanks. Take a step towards effective flood prevention and sustainable water management with our comprehensive resource.
All of the calculations are based on using a well graded gravel material to backfill with. Non regular pea gravel or shingle is ideal, between eight and sixteen millimetres thick. Ten is usually the most commonly available size. The tank should be graded around the sides and also a hundred-millimetre underneath, on top you can use added material or SXF2 or type one. But all size touching the tank should be in a well graded, roughly 10-millimetre pea shingle.
It is to provide a facility so that the storm system is not overwhelmed. It is a facility to catch water and store it and will be released at a controlled rate, rather than the extra storm water just going down the pipe at one time. It is a way to hold, store and release water at a controlled rate to not overwhelm drainage systems.
There is no one answer, it depends on the size of the plant and the size of the load. It is not just the weight of the plant itself, it is the weight of the material they could be carrying. The amount of cover will vary depending on the size and loads of the vehicles. With tracked plant, it does tend to be slightly larger surface area in contact with the tank, which means a bigger boot space.
It can be reduced, probably an equivalent weight the load vehicle cover. You can reduce it slightly with track plant because of the larger surface area in contact with the tank. However, there isn’t one area we would do this. If you have a particular machine in mind you can send us the specifications, our technical team help and give you the cover levels or what spreader plates are needed. We can calculate all this for you.
Unlike a soakaway system, they can be much closer to a building. The main thing is that the building load or the foundation load should have no effect on the tank. If you were to draw a 45-degree angle from the foundation, that line should not cross your tank. This as well depends on the tank depths. But they can be close to the building.
Like any drainage, it will need maintenance. However, it is no different or more arduous than any drainage. The majority of drainage systems will require periodic flushing or some maintenance. Therefore, should form part of your regular maintenance plan.
There are two main types of branches attenuation: inspectable tanks and non-inspectable. For non-inspectable tanks, the maintenance usually involves a good silt trap before the tank.
This is so the maintenance would be emptying out the silt trap periodically and after any large storm event, which may form part of your facilities management plan. If it’s an adoptable tank, it might form part of your water board’s responsibility.
Inspectable tanks though are available for if you need that extra level of maintenance, if you expect it to be a heavy site, it is going to see a lot of silt and a lot of debris. The maintenance can be putting a jet periodically through the run of the tank and giving it a proper flush. Camera inspections are available for inspectable tanks.
Maintenance will be required for all stormwater tanks but the level of such will depend on the type of tank you have and who’s looking after it as well. Whether it is been adopted by your water board, it tends to be a bit stricter than a private company looking after it.
The main tests which need to be carried out are carried out tests up to CIRIA guidelines. CIRIA who writes the SuDS manual. It is a guidance for sustainable drainage systems. We test in accordance with CIRIA guidelines by independent test facilities. We test short-term compressive strengths, long-term peak. Long-term peak is the amount that these tanks are affected over their life, this is to make sure that we design all of our tanks with an excess of 50-year design life. Long-term peak tests are carried out over about 10,000 hours, to make sure that we are confident in the results that are done by independent test facilities. Compression and peak are two of the main tests which most customers would have heard of. We test up to CIRIA guidelines and also have full BBA approval on the majority of the EcoBloc range, we are also testing up to BBA standards as well, and that’s independently verified by the British Board of Agreement.
Void ratio is the volume of water that can be stored in the tank. There are two types of volume, gross volume, and net volume. If you think you have attenuation create the 1m x 1m x 1m. That is the area of volume of that space is 1m cubed, most attenuation creates for structural stability have something in the middle. For example with a couplet max system, you have an area inside the system that’s going to be taking up plastic. That is essentially the area within that 1m cubed, as an example, which won’t store water, because a percentage of that area will be taken up by the plastic. Void ratio is basically the percentage of empty space, therefore the percentage of water that can be held. Most crate systems are about 5% plastic inside, so for every 1m cubed of water, 1m cubed of space would hold 950 litres of water rather than 1000 litres of water. That is a 95% void ratio. Graf EcoBloc Maxx holds 96% void ratio, so we can hold 960 litres of water for every meter cubed of space. Our flex and light systems can go up to 97, depending on circumstances, which is a good void ratio. This can help mass plan the design of tanks. If it’s a level 22 tank, that’s not going to make a big difference, but if you have a tank which is designed at a 95% void ratio, which is 1000 cubed or 1500 cubed. Because of our improved void ratio, we can shave quite a bit. We can hold the same amount of water in less space, in less crates. Which is, of course, saving. But there are lots of positive elements in the higher void ratio. Void ratio is basically the volume of water that can be held. Gross volume is the area, and in terms of basic length, width, by height. Volume ratio is the actual amount of water that can be stored in that space.
If you design the tank with access, then you can. We have a system called EcoBloc Flex Inspect, which is an acute system which has channels down the middle to allow access. It can be combined with a Maxx system or it can be just EcoBloc Flex Inspect, which means that the tank is accessible. You could do this by installing integrated access chambers under the tank. These are called video shafts, which can be seen as manholes within the tank. Rather than being outside the tank, you have a mini-manhole inside the tank to instantly access these inspection channels and drainage channels. You can also buy external inspection chambers if you would rather have that option. Would like the more inspectable piece, but would rather access it either via one of the manholes that’s already there or an external inspection manhole. This all means little extra covers, extra excavation and extra manholes at that one site. But it depends on the design.
They are not suitable for man entry. The covers and access chambers are not big enough to send people into the tank for maintenance, but they are big enough for JN CCTV inspection, for regular maintenance you would need for a stormwater tank.
This is something we see frequently in design and for drainage. Permeable paving and gravel above the tanks forms part of the in-water quality element in SuDS. When the water then filters through, rather than coming into the tank with your pipes, if water comes into the tank for your permeable paving and gravel layers, then this gravel will pick up potential pollutants. The water going into the tank is then cleaner and will be cleaner when it’s discharged from the tanks.
It just means a slight change to the install, and means leaving the top of the attenuation tank. You just don’t put an impermeable membrane on the top, you put permeable tanks down and you bring the membrane up to the surface. But it is something we see very often.
We don’t do this as standard as we have inspectable crates that can run through as an alternative to this, but there might be some systems that need this gravel and pipe. For example, our crates are a lot more open so they don’t get silted up, if you have some people that have crates that aren’t as open, they might get a buildup of dirt coming in which can block them up so it defeats the object of them, they will have to have the pipe and stone so that the water is going in and dirt can’t get in the rest of the tank. If they need to inspect the pipe, there are lots of different alternatives to using this. It is a method that some engineers are more familiar with, whereas we have been in the market for over 10 years but the inspection run is something that we still push rather than this option, because it is a lot easier to install.
Deflection is a short term deformation on crates when they are subjected to a vehicle loading on the ground above, which means every time a vehicle. A lorry or a car goes over the tank, the load that goes over the wheel load is a concentrated load on the tank. This can cause it to deflect (dip).
Where you get this is when we are looking at minimal cover.
A lot of the time the minimum cover will be, the minimum cover, because this is where it would fail.
It has to be below a certain figure. We produce calculations in accordance with something called CIRIA-E-680, which is a set of SuDS guidelines. You must keep it below a certain figure to make sure that the ground doesn’t dip or defect, which is more of an issue with tarmac surfaces, hard surfaces, because if they start to dip and slope, it will cause issues. Whereas if it was a grassed area, it is not as much of an issue.
What we do is when we have the drawings, we would look at the cover level and make sure that they are getting the cover needed for the loading.
We have different crate options. Our go-to would be either our EcoBloc Maxx or our EcoBloc light, both of which are not inspectable. What we would then do is install our EcoBloc flex inspect, which you can inspect. It allows a different setup of the crate. You can either get a jet or a camera through. Our EcoBloc flex inspect, you can have internal inspection shafts, what we call Vario shafts, which is included in the volume. You can have internal chambers where you can get access into the system without having any need for an external manhole. This helps to reduce the amount of connections and debris into the tank.
This isn’t something we offer as standard. But can be done. The things that we would have to look at is if we have put on this alternative forward, or where the pipe is situated. When it comes to install, if it is in the middle, the pipe and stone runs along the middle of the tank and you have the pressure from the crates either side and the backfill. This keeps the pipe and stone in place when you are wrapping up the tank. Whereas, if it was to be situated towards the edge of the tank, that is when you have not got that pressure coming in from either side. There can be delays on the install if anything were to happen or if it is not keeping it in place. The best thing to do is send us over the drainage drawings and we can then have a look to see what we would put forward and what the best solution is. In short term, yes, it can be done.
You can have internal corners. It is something that we try to avoid. If we have drainage drawings, we will always try and look whether we can go deeper to avoid them. But they can be done. It just creates weaker points, if they can be avoided, then it’s best to. However, with our heat weld engineers, they can still make sure that it’s heat welded and watertight.
In terms of how flexible tanks are constructed using geocellular crates, you can have any design. Obviously, the regular shapes are a lot easier for the contractors to excavate, because there’s nothing worse when you have different shaped tanks with lot of internal corners. We understand sometimes it has to be done, with all the new works that are going on, especially when they’re in crowded areas, you have to avoid certain things and pile caps. When that happens, you don’t have any option. We will always try and put forward the best design, but they have dimensions that you have to stick to, you cannot cut crates. We would always put forward an alternative to what’s been specified. But, there is no limit, it’s just whether we can make it a better solution or not.
The advantage of installing an underground storage tank for attenuation purposes is that it maximises land utilisation. Unlike ponds or swales, which take up valuable surface area, an underground tank allows for the use of space above it for essential amenities such as car parks, roadways, green spaces, and even parks. This is especially beneficial in densely populated areas where land is limited but development is necessary.
By placing the tank underground, the space is not lost or wasted. It remains available for various purposes while fulfilling the attenuation function. Underground tanks can be designed to be either light duty or heavy duty, depending on the specific requirements and location.
The alternative of using ponds or swales often results in empty spaces that serve their purpose only during storm events. They can appear as grassy holes or reed-filled areas, providing little value or wildlife habitat most of the time.
In many cases, people may not even realise that attenuation tanks are present beneath their back gardens or even in park spaces. These tanks can be seamlessly integrated into various locations, including roundabouts, without compromising valuable surface space.
The key advantage of underground storage tanks is the efficient use of available land, ensuring that no space is wasted and that development can proceed without sacrificing essential amenities.
When sizing our tanks, we don’t specifically include a buffer volume like you would with a wastewater tank for accommodating extra visitors. It’s a different process. Our engineers take various factors into account. They calculate the current runoff rate from the site, the amount of non-absorbable runoff, and consider the downstream system. They also consider Climate Change by applying a safety factor of around 30-50% to account for anticipated increased rainfall.
The tanks are designed to handle rare storm events, such as one in 30 or one in 50-year storms, and accommodate the projected changes in weather patterns. So while there may be some additional volume in the tank, it’s not a buffer in the traditional sense. Our goal is to match the tank size as closely as possible to the drainage plan we receive, considering all these factors beforehand.
The purpose of flow control in an attenuation tank is to store water and prevent overwhelming storm sewers and drains. It slows down the flow of water exiting the tank, ensuring it is slower than the incoming flow. This gives the tank time to drain gradually and prevents flooding or backup issues downstream.
Flow control devices come in different types. For smaller tanks, a simple orifice plate with a smaller hole than the incoming pipe can be used. Larger tanks may utilize bespoke vortex flow controls designed to match the tank’s dimensions and flow rates. These devices create a swirling motion to slow down the water, and their size is determined to match the capacity of the downstream system.
Overall, flow controls are crucial in regulating the water flow and ensuring it doesn’t exceed the capacity of the drainage system.
A percolation test measures how well the soil drains and determines its suitability for a soakaway or an attenuation tank. The test involves digging a trial trench of specific dimensions and timing the water as it drains. The pit is filled to the expected tank level, and the time it takes for 25% and 75% of the water to disappear, as well as the emptying time, is recorded. The test is repeated three times for consistency, and the average of the results is taken.
For tank lengths exceeding 10 meters, the process is repeated at intervals to ensure consistent infiltration rates. Calculations are then done using the recorded values to determine the median value and the soakaway area. It involves working out volumes, surface areas, and timing calculations, which can be facilitated with provided documents.
The key is to conduct the test accurately, record measurements diligently, and consult with a qualified professional for further assistance in the calculations.
To size a stormwater attenuation or soakaway tank, we need specific information. It’s not just about the volume needed; the dimensions are crucial. Length, width, and height are the key factors to determine the appropriate base plates, end plates, and ventilation services required. Providing a drainage drawing is the best option as it gives us a comprehensive understanding of the project. It allows us to calculate the necessary components and provide an accurate price.
Additionally, knowing the location of the tank is important. Whether it will be situated under a park, green space, driveways with light car loading, or more heavily trafficked areas like roads or car parks, helps us design the right plate system to meet your requirements.
If a drainage drawing is not available, providing the length, width, and height of the tank is crucial. This information allows us to propose a suitable solution based on the available space. However, if more detailed calculations are required, we may request additional information during the order stage.
In summary, the dimensions of the tank, along with the location and a drainage drawing if possible, are the key pieces of information we need to properly size and propose an appropriate stormwater attenuation or soakaway tank.
Stackable crates offer several benefits when installed. Firstly, they significantly reduce installation time as workers can quickly feed the crates into place. The system is designed to be user-friendly, making it easy to handle and install. Additionally, crate systems can be tailored to fit into unique spaces, including odd shapes or L-shaped configurations. This customisation ensures optimal use of available space. By using stackable crates, you can save time, energy, and reduce the carbon footprint associated with the installation process. The simplicity of the system, with its convenient 90-degree turn, makes it straightforward to use and eliminates the risk of errors. Overall, stackable crates provide an efficient and time-saving solution for stormwater management installations.
There can be a build-up of silt at the bottom of the tank when using blocks or crates, but it depends on the design and maintenance plan. A properly sized silt trap installed before the tank can catch most of the silt. Regular maintenance, including emptying the silt trap, is crucial. For adoptable tanks or situations with a high possibility of silt accumulation, an inspection or jetting channel can be designed into the tank. This allows for periodic high-powered jets to flush out the silt. The level of silt accumulation will vary based on the effectiveness of the maintenance plan and the quality of the silt trap. Some tank designs also incorporate inspection chambers or integrated shafts to facilitate easier maintenance. Overall, a well-designed maintenance plan and the inclusion of proper silt traps can help manage and reduce silt build-up in the tank over time.
To ensure a successful installation of the tank, there are specific requirements for the excavation. First, we need the excavation to be dug according to our provided drawings, with a 500-millimetre working border around the edges. This space allows our team to access the sides and install the tank effectively.
The excavation should be graded, stepped, or leveled to provide a safe entry and exit. It’s crucial to prepare the bottom of the excavation with a layer of shingle or gravel, ideally 50 to 100 millimetre thick. The preferred material is pea gravel or pea shingle, around 10 millimetre in size. This material compacts well and doesn’t contain excessive fines that could wash away or create voids under the tank.
If pea gravel is not available, alternative materials may be considered, but our technical team will need to review photos to determine their suitability. It’s essential that the material is non-angular to prevent any damage to the tank’s membrane or textile, as these tanks are designed to store water. Materials like sharp sand or 6F2 are not suitable for the base of the excavation.
In summary, providing the required working space, grading the excavation, and using the appropriate non-angular shingle or gravel will ensure a proper foundation for the tank installation.
The recommended material for the base and backfill of a stormwater tank is non-angular pea gravel or shingle. It’s crucial that the material is non-angular and doesn’t contain excessive fines or sharp objects. Typically, a size range between 8mm and 16mm is suitable, and non-angular options are commonly used.
The minimum amount of cover you can have on top of a tank is 250 millimeters, suitable for pedestrian-only access without any vehicle loading. The maximum amount of cover depends on the type of crates used. Light-duty crates require less cover, while heavy-duty crates can accommodate greater loads. The maximum recommended cover above the tank is 2.75 metres. For specific projects, site-specific calculations can be done to determine the optimal amount of cover based on loading requirements. The information regarding minimum and maximum cover will be provided in the spec sheets or can be obtained through site-specific calculations based on the drainage drawing.
The main tool we use for welding the tanks is called a wedge welder. It is used to overlap the membrane sections and seal them together. We also use a heat gun for sealing the plastic on adaptor plates. The wedge welder is a specialist equipment that provides superior welds compared to tape. It is the best tool for the job and ensures high-quality results, which is why we offer a guarantee on our welding.
When it comes to attaching side plates or end plates to an attenuation tank, it’s a straightforward process. With the Max system, you don’t need side plates for every crate. You simply build the tank to its final shape and then attach the side plates along the outer edges for stability and to prevent backfill pressure on the membrane. It’s as simple as clipping them onto the tank.
For the Reflect system, which includes the eco block flex crates with two solid sides, you need to turn the crates as you go. For example, if a crate is on a corner, you turn it so that the solid sides align with the tank’s edge, and then you add plates to the corners.
If you need further clarification or assistance, we are available for one-on-one discussions, phone calls, or video calls to guide you through the process.
Yes, construction vehicles can drive over the tank once it’s installed, but it’s important to ensure that the site provides sufficient cover to support the weight of heavy vehicles. This consideration is crucial, especially during the construction phase when vehicles may be driving over the tank. If there are cranes or heavy equipment involved, we need to assess the specifications and possibly use spreader plates to distribute the weight appropriately. Each case is unique, so we need specific information to provide the right guidance.
The proximity of an attenuation tank to a building depends on its depth, ground cover, and foundation design. Shallow tanks with minimal cover can be placed closer to buildings, while deeper tanks typically need to be located further away. The critical factor is that the tank should not bear any structural load from the building’s foundations. To determine the suitable placement, imagine drawing a 45-degree line from both sides of the building’s foundation. This line should not intersect with any part of the attenuation tank. In some cases, tanks can be directly beneath buildings, such as in parking structures where space is limited. However, careful design ensures that the tank does not affect the support columns or foundations. The specific placement will vary depending on the tank shape and building’s foundation design.
It very much depends on the crate type. We have a rain bloc crate, which is a traditional one-piece crate, which can go as far as 7 meters underground, but it will depend on the soil type essentially. Heavier clay soils have more of a lateral loading and more loading on the tank, and so couldn’t go as deep.
But in perfect conditions, a rain bloc crate can go as far as 7 meters underground. Graf EcoBloc Maxx, a maximum of 5 meters for the soils that we deal with. But again, quite often the actual loading, where we put in the figures and the cover labels and everything, it’s more like somewhere between 1.5 – 2.5. It is very site specific. But the absolute maximum, I would say, for an EcoBloc range is about 5 meters underground. But often the surrounding conditions won’t support that. Again, we have to do calculations for every site, which we will do, but that is your maximum labels.
Yes, they command what we would call the water quantity part of SuDS. SuDS has four elements; bioimmunity, biodiversity, water quality and water quantity. And so water quantity is where the SuDS element with attenuation tanks comes in just because essentially it’s dealing with that quantity of water. An attenuation tank does not constitute a SuDS system, it’s part of a SuDS system. A SuDS system is a entire holistic design to now protect them in the same biodiversity of the site and now for future generations. But an attenuation tank is a very important part of SuDS to cope with that water quantity.
I mean, it’s really, there’s a few components. The first thing you do is when you’ve excavated a nice, level flat base now, so the tank can sit nicely on the surface. You would start with a layer of geotextile. We’d use like 300 gram geotextile, which would protect the tank from any potential sharp stones or anything like that in the soil when it’s back-filled.
Then you would put down a layer of impermeable geomembrane on the base, which is the black plastic liner which essentially makes the tank a tank. And then, that’s when you start adding the crates. So the crates would be installed in the format of the design, which has been specified, has been approved from a contractor. So as the crates are in the required shape, essentially, it’s almost like wrapping a big present. The black plastic is brought up the sides and a lid piece is put on, and then is welded shut, to create a sealed tank system.
Obviously, before that final seal, we’d add things like pipe connections in, so that water can enter in and go out the tanks, whereas kind of in stubs, black pipe stubs put on, so that the tank can be joined into a single pipework. Then once it’s all been sealed up, once the black membrane has been sealed, usually using something like a wedge welder, which creates a nice double seam, tight double seam on the top of the tank, then we put a final layer over the top and right down the sides of that geotextile material. Again, to protect the top and sides also, from sharp stones and things like that.
Then it’s back-filled essentially, so it’s a very simple process, but hard to explain. One of those things you probably need to see.
It’s really not recommended. No. I mean, I’d say, probably, the basic answer is no. But we’ll never say never. If you had a big enough soakaway, and a clay with poor soil, well then theoretically, you could. But before any soakaway, a soakaway is always the preferable option with designers. Essentially, it’s always looked at first, and there will be a percolation test done on the soil, to see whether it’s practical.
But also, if you have to have a massive attenuation tank to soak away a small amount of water, then it’s really not a practical solution, because the soil is just not permeable enough, to drain it. So an attenuation tank becomes the best solution, to essentially carry the water down, and dispose of it through other water courses, or through the storm sewer system.
Fairly simple, really that so these tanks should sit empty majority of the time, or at least not completely full. So, the air which is in the tank, half the time does fill up or there’s a storm event if it’s not filling up the entire tank and the air which is contained within the structure needs to escape. So, you’ve got a vent pipe up to the surface and usually run, the customer will run a vent pipe from the top of the tank to the surface and usually, at a safe area, like (?0.37) or with a grated cover. So that when water enters the tank, the air has somewhere to escape to. And that is as simple as that essentially, so as not to compromise the tank welding or anything like that or the cover. So, when water comes in, it needs to leave and so the vent pipe allows it to do that.
Well, I’m going to just start by expressing first the differences and the nations of the UK, like the three main nations that’s in Northern Ireland as a completely different set of bodies and everything. But in Scotland, SUDS are a legal requirement for new development, except for single dwellings, small single dwellings and things like that, so there is a framework there. But it just says that you have to incorporate it into your development.
Wales, it’s also mandatory, but again, it goes slightly further again where you have to have your SUDS plan approved by the national approving body and before construction can begin, has to be in before construction can begin, and it must meet the specific Wales national standards. England is the only the [inaudible 00:01:32] it’s kind of recommended. The guidance states that it’s mandatory for… It’s not mandatory, sorry, for planning applications, but they highly recommend it for large developments unless it’s inappropriate to do so.
Again, that is a bit wooly essentially, as what is inappropriate. That will vary per council area potentially, that could vary per developer, whether you could put cases for when something’s appropriate when it isn’t. Is that cost, is it space? It’s a bit of a gray area. So I mean also, England being the largest nation of the UK, to get back to the question, if it was to become mandatory, it would mean that every new site essentially then it would have to have a SUDS system designed and in place and it would have to be considered at the early stage of development. And SUDS [inaudible 00:02:25] best when it’s considered early, designed early. Have be better prepared, contractors have to be better prepared, sites have be better prepared.
Everything would have to go in as per the planning application without deviation. It would also be much and have a fantastic effect on the water quality, quantity, et cetera going forward. Every site would need to consider the runoff, but it could potentially… It’s one of those until it happens, we don’t know. But it could cause delays potentially in state statin. Would the planning bodies have enough gear adopted and all these extra applications coming in? Could some sites not be approved? Who knows, potentially. That’s the kind of downside. But really the upside is massive if we were to put SUDS in every development.
We suggest to say, as we’ve talked about the four elements of SUDS before, the water quality element, which is environmentally conscious people, water quality should be in everybody’s mind. Water quantity to reduce flood risk for pre-existing developments and people living in pre-existing development where SUDS was a thing, putting in a development should not increase the risk of flood to other people already living in the area. And the amenity in biodiversity, which just makes the spaces better for the people in the environment.
It’s one of the impact will gain, like everything, with upon the impact it’ll have in the construction industry. It will depend on the amount of planning if for work done by the governing bodies before they make the regulation if they choose to do so. Actually, it’s only under review at the minute, but the environmental uptick could be massive going forward.
Because I guess what it would mean is most kind of projects now usually look at probably maybe the quantity side in England. Obviously in Scotland and Wales, it’s all mandatory anyways, there’s not much difference there. Especially in England, from the sounds it’s just the runoff that’s thought about, not kind of the quality biodiversity immunity. It’s more we just need to deal with the runoff to make sure there’s no flooding, but they don’t think about the other aspects to SUDS.
Very true, and I must say that as much, as I said, it’s a bit of a silly legislation, majority of sites and developers in these days are thinking about a SUDS system. They’re already considering it, whether it becomes [inaudible 00:05:06] to get them approved, if the regulation changes might be the consideration. But most systems, most large developments certainly are considering SUDS at the moment as you see.
I don’t want anyone to think watching this that the water quality in England is off the chart bad. It’s not. And I don’t know that for fact, so I don’t know the testing, but in majority of the time it has been considered anyway just as good practice. But the fact it’s just been in every development, even your smaller developers, singled, dwellings, et cetera, would need to consider potentially a SUDS system. And as you said, the quality that they’re considering, the quality, the immunity, the biodiversity, it’s all about the future. It’s protecting these spaces for the future, protecting them for other people.
So key considerations are things like… Also, you just mentioned the soil type, other things would be things like rainfall, local rainfall for the area, climate change considerations, the size of the [inaudible 00:00:23] the size of your development. Discharge rate, allowable discharge rate into the local storm sewer system, and the slower the discharge rate allowed… The less the storm drains can cope with, the larger your tank has to be to because it has to be released more, whether it’s released more slowly. You have to consider if there’s groundwater in the area. You have to consider also the later use of the crates, what will it be under? Will it be under a landscaped area? Will it be under a really heavily trafficked area? There’s quite a lot of different considerations to take in for design of your tank, but there are the main ones.
They can quite significantly impact. So the first impact really is, is it an attenuation system or a soak away? So, your type of soil will impact which solution, essentially, you need to think about. Well draining soils will drain, which are with very little groundwater are usually suitable for soak away systems. Obviously, you have to do our testing to test that. So that’s the first way it will affect your system, but assuming it is an attenuation tank that is required, different soils can affect the tank longterm.
So thinking about something like heavy clay soil will put additional lateral loading and weightbearing on the tank over the course of its life. We design tanks for a minimum and SuDS guidance is that we should design tanks for a minimum design life of 50 years. So the heavier the soil, think about 50 years worth of potential pressure on the tank from heavy clay soils means that you have to think about the crate type that you’re using. You have to think about the crate type you’re using, you have to think about the depth of the tanks, the amount of loading for the cover and everything on top of it, that kind of thing.
So it will potentially, can have an impact for the longterm life of the crate. And you have to think about the backfill, obviously you should never really put [inaudible 00:01:37] material directly around the tank, it should be well created gravel material originally backfilling the tank. So it will have been affecting that kind of thing as well.
Yes, stormwater attenuation systems can be retrofitted to existing buildings if there is enough space available and the existing drainage levels can be matched. It can be a bit challenging because the drainage infrastructure is already in place, and you need to ensure that the system can hold an adequate volume within the available space. Planning and forethought are required for successful retrofitting. Additionally, other stormwater management elements like rainwater harvesting systems for irrigation or tree pits can also be added at a later stage. However, it’s important to consider practical limitations and feasibility during the planning process. In summary, retrofitting stormwater attenuation systems is possible but requires careful consideration and planning.
An attenuation tank can potentially cause flooding if it’s not properly maintained. Regular silt removal and flushing of the tank are important to prevent blockages. After a large storm, clearing silt traps, gullies, and channel drains is crucial. In rare cases, pipe blockages could cause surface water flooding.
However, extreme storm events are infrequent, such as one in 100 or one in 200-year events. These are rare occurrences, and most people would never experience them in their lifetime. Even in these rare cases, an attenuation tank can significantly reduce the impact of flooding compared to having no tank at all.
While Mother Nature can sometimes bring unpredictable and extraordinary events, the frequency of such occurrences is very low. Safeguarding against these rare events is challenging, but attenuation tanks provide valuable protection against typical storm events in most cases. The massive storm events seen in places like the US are unlikely to occur in the British Channel or North Sea regions.
An attenuation tank is a simple system used to hold excess water. It receives water through multiple inlets, which can include pipes and channel drains, and usually has one outlet. The tank acts as a void to allow the water to build up and prevent overwhelming downstream drains during heavy storms. The outlet typically contains a flow control device, such as an orifice plate or vortex flow control, to regulate the water’s discharge rate. The tank size is designed based on factors like rainfall, surface area, and climate change considerations. If designed properly, the tank should always have the capacity to cope with the site’s water volume. Offline attenuation tanks are less common and have a single inlet and outlet at the bottom, filling and draining during significant flow events. It’s crucial to position the outlet at the tank’s base to ensure complete drainage. Failure to do so may turn the tank into a retention tank, which can lead to lost capacity and increased flood risk.
