BYTNAR - TALKS
EPISODE 024 - APPROVED DOCUMENT H - DRAINAGE AND WASTE DISPOSAL
This episode is for people who want to know more about Approved Document Part H – Drainage and Waste Disposal.
You should like this episode if you ask yourself questions like:
What are the key requirements for foul water drainage systems according to Requirement H1 in Approved Document H?
How can blockages, leaks, and foul air ingress be prevented in a building's drainage system?
What standards and guidelines apply to wastewater treatment systems and cesspools as specified in Requirement H2?
How should rainwater drainage systems be designed and maintained to comply with Requirement H3?
What are the best practices for rainwater management, including the use of soakaways, watercourses, and sewer discharge?
What considerations are necessary when building over existing sewers to avoid affecting drainage systems (Requirement H4)?
Why is it important to have separate systems for surface and foul water drainage, and how should these be designed as per Requirement H5?
What are the rules for combining surface and foul water drainage, and how should this be agreed with the local authority?
How should solid waste storage be planned to be vermin-proof, weather-resistant, and hygienic in compliance with Requirement H6?
This is Bytnar Talks the Engineer Takes on Construction Episode 24 hi I'm Piotr Bytnar each day I help my clients plan and design building projects through Bytnar Limited a Consulting Chartered Structural Engineers practice my biggest passion and the corner stone on which I've built my business is finding clever solutions for construction projects I am a chartered structural engineer and a bing software developer so you can rest assured that I will strive to talk about the best practices and the use of new technologies in the industry and if you're embarking on a construction project or are involved in planning designing and building the world around us you'll find this podcast useful approv document H drainage and where [Music] disposal hi and welcome to bitnar talks your favorite podcast on all matters of architecture engineering and construction it is Saturday the 13th of July 20124 and I'm here back with you with the 24th Episode and information on approved document H drainage and waste disposal as however before I go to covering material of this episode let's have a look at what was covered last week in the last episode I talked about the approved document G sanitation hot water safety water efficiency every single time I like to reiterate that the primary primary responsibility for compliance with building regulations lies with the building owner followed by those involved in the initiation design and execution of the work including principle designers and contractors on domestic projects this will be mainly principal designers and contractors though as we cannot expect the homeowner to know all all nitty-gritty about the building safety act and and other but we should do all parties must be competent and the building owner must enable proper coordination generally and in light of Regulation 8 emphasis is put on a health and safety but here requirement G2 deals with another subject with a subject of water conservation exemptions from building regulation are detailed in schedule 2 and regulation 9 of the building regulations key coverage points of the last episodes are the requirement G1 that deals with a reliable supply of wholesome cold water with adequate flow and pressure avoiding waste and contamination allowing for Alternatives like like rain water or gray water to be used in the property if properly installed and designed requirement G2 focuses on water efficiency setting a standard of 125 L per person per day for the property or a little bit less of 110 lit per person a day under optional requirements that are being put as a condition of planning application requiring calculations for total net water use of the order the limitation on fittings approach so two ways of of dealing with how much water the building uses G3 is a requirement that addresses hot water supply ensuring safe Heating and Delivery Systems must have safety measures including thermostats and relief valves larger hot water containers vessels systems over 500 L or 45 kilow require design by qualified engineers and notification to building control if unvented requirement G4 stipulates adequate sanitary conveniences with hand washing facilities considering the building type and uses houses and flats need at least one water closet with nearby hand washing separated from food preparation area and located at the story of Entry to the building G5 requirement requires a buff room with a fixed buff or shower and a wash basin in houses and flats and compliant water discharge and if you do not know on which side you should have your hot water tub it is left it is left side once and for all so if your plumber says otherwise well he might have made a mistake so direct him back to G5 requirements of this approved document requirement G6 mandates a SN in food preparation area with discharge through proper systems as ever additional hand washing facilities may be required in regulated Food hygiene areas all installations must adhere to approv standards ensuring safety efficiency and compliancy in any water system in a building in this episode I will move to the approved document H and the considerations of drainage and waste disposal so without Ado let's dive into this not so much palatable approved document [Music] H in this episode I'll talk about the statutory guidance contained within the approved document G sanitation hot water safety and water efficiency this episode will follow its standard format for the material talking about the approved documents I will first read you the text of the actual regulation and then we'll go Section by section dealing with with what's required the document contains guidance for the discharge of requirement H in Parts H1 to H6 so let's get into the nitty-gritty of this approved document shall we starting with the text of the legislation and this one is pretty long longer than the trip to a bathroom that's for sure so brace yourself cuz here we go foul water drainage requirement h1.1 an adequate system of drainage shall be provided to carry foul water from appliances within the building to one of the following listed in order of priority a a public sewer or that is not reasonably practicable b a private sewer communicating with a public sewer or that is not reasonably practicable C either a septic tank which has an appropriate form of secondary treatment or another wastewater treatment system or where that is not reasonably practicable the as pool point two in this part fowl water means waste water which comprises or includes udes a waste from a sanitary convenience bday or Appliance used for washing receptacles for f waste or B water which has been used for food preparation cooking or washing requirement H1 does not apply to the diversion of water which has been used for personal washing or for the washing of clothes linen or other articles to collection systems for reuse requirement H2 wastewater treatment system and sesss point one any septic tongue and its form of secondary treatment or the wastewater treatment system or Cesspool shall be so cited and constructed that a it is not prejudicial to the health of any person B it will not contaminate any water cause underground water or water supply C there are adequate means of access for emptying and maintenance and D were relevant it will function to a sufficient standard for the protection of Health in the event of a power failure point two any seting tank or holding tank which is part of a wastewater treatment system or SES shall be a of adequate capacity B so constructed that it is impermeable to liquids and C adequately ventilated point three where a power water drainage systems form from a building discharges to a septic tank wastewater treatment system or sesp a durable notice shall be affixed in a suitable place in the building containing information on any continuing maintenance required to avoid risks to health requirement H3 rainwater drainage point one adequate provision shall be made for rain water to be carried from the roof of the building two paved areas around the building shall be so constructed as to be adequately drained point three rainwater from a system provided pursuant to sub paragraph 1 or2 shall drainage to one of the following listed in order of priority a an adequate sway or more other the adequate infation system or that is not reasonably practicable a water course or where that is not reasonably practicable a sewer requirement h3.2 applies only to paved areas a which provide access to the building person to requirement M1 access in use or M1 access to and use of buildings Ed in dwellings requirement M2 access to extensions to buildings or the dwellings or requirement m4.0i access to and use of dwellings point B which provide access to or from a place of storage person1 to requirement H 6.2 Solid Waste storage or C in any passage given access to the building where this is intended to be used in common by the occupiers of one or more other buildings requirement h3.3 does not apply to the Gathering of Rainwater for reuse requirement H4 building over sewers point1 the erection or extension of a building or work involving the underpinning of a building shall be carried out in a way that is not detrimental to the building or building extension or to the continued maintenance of the drain sewer or disposal main point two in this paragraph disposal main means any pipe tunnel or conduit used for the con conveyance of affluent to or from a sewage disposal Works which is not a public sewer point three in this paragraph and paragraph H5 map of sewers means any records kept by a seage Undertaker under section 199 of the water industry act 1991 requirement H4 applies only to work carried out a over a drain sewer or disposal main which is shown on a map of sewers or B on any side or in such a manner as may result in interference with the use of or obstruction of the axis of any person to any drain sewer or disposal main which is shown on any map of sewers requirement H5 separate systems of drainage and a system for discharging water to sewer which is provided persuant to paragraph H3 shall be separate from that provided for the convenience of foul water from the building requirement H5 applies only to a system provided in connection with the erection or extension of a building where it is reasonably practicable for the system to discharge direct directly or indirect directly to a sewer for the separate convenience of surface water which is shown on a map of sewers or be under construction either by the sewage Undertaker or by some other person where the sewer is the subject of an agreement to make a declaration of vesting persu to section 104 of of the water industry act 1991 requirement H6 Solid Waste storage1 adequate provision shall be made for storage of solid waste two adequate means of access shall be provided Point 2 a for people in the building to the place of storage and B from the place of storage to a collection point where one has been specified by the waste collection Authority under Section 46 household waste or section 47 commercial waste of the Environmental Protection act 1990 or to a street where no collection Point has been specified so this is it are you still here excellent let's move on to what does all that mean to Secretary of State like with all the other requirements following regulation 8 nothing more needs to be done than assuring reasonable standards of health and safety in all requirements that deal with such issues however paragraph H2 is excluded as it deals with the prevention of the contamination of water it really goes without saying but I will repeat that anyhow the quality of workmanship should follow the current St standards and the due consideration for the health and safety of people laying the drains or working in confined spaces this this this matter should be fully addressed before the work commences or during the work so now off to the requirement H1 that deals with foul water drainage in section one of the document we will find out what the expectations are for the system the secretary of state is Happy the requirement is met as long as the outfall of the water is addressed properly the system is so designed to minimize blockages leaks floodings and can be cleared of blockages and the Ingress of Power air into the building is prevented the system should have sufficient capacity which will depend on the size of the pipes used and the gradient and the document provides the minimum requirements the reading of the document deals with the domestic building and small non-domestic buildings appendix H H appendix a deals with larger buildings but for complex situations outside of the scope of this document we are referenced to use guidance of British standard European Norm 12056 the information here provided assumes that the periodically that there will be at least five liters of water flush through the system the document requires all discharge points to be fitted with a serviceable trap to prevent foul air from entering the house the retained Water Seal should be at least 25 mm but it is Gally high in line with the document and increases in value at the with the diameter of the Trap so for toilets or rather trap diameters of 65 mm and over that it's the Trap is the water Ser is 50 mm and below that it's 75 mm there are some except exemptions and easing of the requirement if there is another trap along the way like a gley the limitation on the location of the branch pipe discharges in terms of discharging into open Hoppers otherwise discharge into another Branch pipe gy stock or drain is perfectly okay in case of the direct drain connection such needs to be from ground floor appliances and the water closet and water closet floor cannot be higher than 1.3 met above the invert level of the drain Branch pipes should not cause a cross flow to happen connection of Branch pipes to stacks on opposite sides at the same level is prohibited and the minimum offset Dimension is given in the document the offsets are taken by Center Line of all drainage run so and are between 110 to 250 mm depending on the branch pipe diameter and the stock diameter Solid Waste Branch pipe manifolds can be used instead it should be noted that a branch pipe connecting at the lowest point needs to be at least 450 mm above the invert level of the drain at the bent tail for buildings under three story height 75050 mm up to five stories for taller buildings or where the minimum cannot be achieved the discharge should be either direct through it its own stack or to a galley interestingly similar provision will need to be put on the discharge from first floor appliances in buildings over 20 stories in height Branch pipes can discharge the Sub Stop stock and the condensate from the boiler can also discharge through a sanitary pipe work but needs to be washed over by discharge from other appliances due to the lower pH of water that can otherwise damage the pipe so either directly into an internal stock or Downstream of the sink size length gradient connection angle and the number of appliances possibly connected to a branch pipe is covered in a document and it accounts for not breaking the water seal due to suction in advented branch which happens when the whole block of water passes through the through the pipe causing a void causing a being a seal sucking everything sucking all of the air behind it as as that's that part of water passes through the pipe vented branches can service longer lens but problems with sedimentation or noisy runoff may become an issue ventilation should be provided maximum 750 mm down the drain runoff and to a higher level than a possible speed over level if the ventilation goes outdors it should extend at least 900 mm above any opening within 3 m radius when it comes to Stacks all should discharge to a drain with a bottom radius as large as possible but not less than 200 mm at the center line offsets or in other words bends in wet portion of the stacks are discouraged but if needed then in buildings up to three story any branch connected any Branch connection needs to be minimum 750 mm away from the offset in taller buildings the offset may need ventilation at its top and bottom Stacks in taller building should be kept inside the building Stacks should be ventilated and of the right size stop Stacks are allowed observing the maximum toilet connection height from the drain tail and the maximum height of the highest Branch Center Line to the drain or Conn ction Center Line of 2 m the termination of the ventilation stock should be 900 mm above any opening within 3 m radius and protected with a termination cage the stack should be serviceable and have roding ice roding access where necessary many different materials can be used for the provision of dischar piping but the choice should be well conceived and installation done properly capable of withstanding in an air tightness test simulating a pressure of at least 38 mm on the water gauge for at least 3 minutes whilst all traps need to maintain the 25 mm Water Seal going into section two which covers drainage outside of the building but before it meets its further destination you no public sewer sespo or wastewater treatment system the house drainage can be separated for foul water and rainwater all combined the fowl drainage should be connected to the public system whenever possible and when it is Within Reach no more than 30 m away from a small development we should rely on the gravity to do the work for us but pumping May sometimes be required larger developments may require to go some distance in order to connect the de the development to the building Undertaker which may mean going through the curtilage of other lands the developer May re requisition the sewer from the undertaken Undertaker who has the power to construct sewage over private land if possible it should be attempted to connect to the existing private sewer that in turns connects to the public system in any case three weeks prior notice to the day of the intent intent for connection should be given to the local Undertaker if there is no possibility of conne connection to the public sewer a sful or water treatment system may be required combined and rainwater drainage is designed to S surcharge and may flood your house especially at low Ling sites or where the basement is below the level of the drainage to mitigate on the possible foul water flooding of your house it is required that in the low risk areas a provision of no return valve is considered flood flood water can discharge through a galley that is at the level lower than the house or that the drainage from that area of the house prone to flooding or entire house is pumped the non return valve should be suitable of a double valve type capable of being locked manually and the house occupants should know of its location and how to operate it the drainage unaffected by a search charge should bypass the protective measures on discharge by gravity layout of the drain system should be simple as straight as possible ventilated and maintainable and the access points provided where the blockages cannot be cleared otherwise connections to other runs should be made oblique or in the direction of the flow using prefabricated components no duct type magic please change of gradient will require an access point access points will also be required close to the bend or at the band location the drain itself Ser in commercial Hot Food Kitchen should be fitted with a grease separator or otherwise capable of removing grease measures controlling rodent movements may be necessary in the system drainage can run under the building if it is laid in at least 100 mm of granula of flexible material and should not be suitable to the forces excerted by the house on the ground as well as due to settlement movement of the house wherever pipes go through structures use rocket pipes both sides of the structure with flexible joints and will provide at least 50 mm of space around the pipe so that the building can move without breaking the pipe naturally all such perforations need to be sealed if the drainage needs to be lower than the foundation formation level and within the meter of it it should be concreted into the level of the foundation's formation otherwise to the level below the formation level of the distance minus 150 mm basically As you move away from the foundation but not to go past the 45° angle minus 150 mm you will not need to concrete in your pipes if we need to account for loading on pipes for whatever reason we are guided to seek help elsewhere there are no special Provisions for the depth of the the pipe cover but whatever it is the pipe needs to be protected it also needs to be at a certain gradient to service the load it is being subjected to between 1 in 10 to 1 in 150 but usually kept within in between 1 in 40 to 1 in 80 so per every meter is either 25 or 12.5 mm drop you know inch and a half inch in old money the size of the sewer should be at least 100 mm up to 10 dwellings and 150 mm above for drainage of all but the foul water the pipe can be as small as 75 mm however if the system is combined we also need to account for the rainfall in sizing of the pipe whenever we need to use pumping installation we are referenced to bn1 1205 Wastewater lifting plants for buildings and sites principles of construction and testing bn1 12056 gravity drainage system inside buildings and BN 752 drain and sewer systems outside building when we use the pumping the chamber receiving the fluent needs to be capable of receiving 24 hours of inflow at the minimum of 150 L per person per per per day it follows the water usage cup and then some all types of pipes can be used underground including and all-time favorite vitrified clay but also concrete gray iron ductor iron as well as the flexible types made of plastic this should be flexibly jointed and in no case protrude into the flow of sewage the beding and back feeling will depend on the depth of excavation size and strength of the pipe local Undertakers generally concrete their installations in but we can go lighter on our installations concrete installation will require a movement joined with compressive board formed at Junctions the bedding and back filling material for pipes follows the mitigation of pressure points on the pipe that could break it so uniform material with no vegetation Stone larger than 40 mm lamps of clay over 100 mm of Frozen material is generally considered good enough in most cases however ever you'll find this laid on some type of granular material either single size or graded from 5 mm to 40 mm depending on the diameter of the pipe 10 mm for 100 mm pipes to maximum Dimension use for pipes over 600 mm diameter minimum and maximum ground cover for different size pipes of different types in different situations is given in the document starting a minimum 600 mm for fields and 1.2 2 m otherwise for rigid pipes and slightly lower 0.9 M for thermoplastics pipes late as shallower depths will require a bridging slab over them with a layer of compressible material between the pipe and the slab to maintain and service drains access points drain access points need to be introduced in the system and the guidance interprets the reasonable spacing and placements of such roding eyes access fittings inspection Chambers and man holes are typical points that could allow roding the guidance considers roding in the direction of flow only the placement of such needs to be considered at head of the drain run Bend change of gradient change of pipe size and Junction if it can be roded from one side only type and spacing of these access features is Guided by the document and depends on the depth of the invert level and the size of the pipe spacing of the AIS points between 12 and 200 M depending on the type of axis used 12 M from the start of the drain to 200 M between man entry size drains and sewers the material used for the formation of access points follows the material used for the pipes themselves the junction of pipes in the inspection chamber should follow the direction of flow covers to access features should be appropriate for the location airtight and durable may need to be lockable also the guidance requires metal steps in deep manholes however current practice prefer steps to be brought with the Plummer due to the possible corrosion of the fixed steps and surprised fall of the personel the work of lying the pipes connections and forming inspection Chambers or man holes should be of the appropriate quality if piling takes place close to the pipes the pipes may need to be exposed temporarily and piling should not take place too close to pipes meaning a minimum of two times the diameter of the pile pipe to the nearest diameter of the pile to the nearest pipe the gravity drain and private sewer systems should be tested following the construction we are allowed to choose between a water or air Test air test for pipes up to 300 mm diameter will be loading the system with the pressure of 110 mm on the water gauge for 5 minutes with an addition of 100 mm of pressure for the next 7 minutes max drop of pressure being 25 mm of water water test and tast filling the system with water to a level of Maximum 5 M over the lowest in level but to minimum of 1 M over the highest invert level such field system is then left for an hour to Prime the system then topped up to be within 100 mm of the required level the system is fine if the loss per square meter of surface area does not exceed 0.15 L for pipes only 0.2 L for pipes and manholes and 0.5 for manholes only the gu guidance further references as to Alternatives of b191 vacuum sewer systems outside buildings or bn1 1671 pressure sewer systems outside buildings both standards are now are now withdrawn now although there are no building regulations requirements to maintain the drains the local Authority and The Undertakers have far more reaching rights that may include inspection of your drainage system and order for repair sealing of old drainage or its removal similarly with the repair and alteration to drains a on day notice needs to be given to the local Authority unless it's an emergency another important thing to keep in mind is the adoption of sewers basically under water industry act 1991 section 104 agreements to adopt sewer or sewer disposal works at Future take you build the infrastructure for the Undertaker to take care of certain standards of work needs to be met but these are generally available and can be agreed upon with the Undertaker single dwellings to do not fall under the consideration requisition of sewage section 98 from the undertaken may be the only way to connect your development of the building sewer when other C cartilage stands between you and them under Section 102 existing drainage may be adopted if it meets the criteria and the adoption May proceed from the developers inquiry or on the Undertaker Undertaker on Vol volition section 106 gives the right for the connection to public sewer with a 21-day notice upon agreeing on the technical details of such connection section 107 gives rights do the Undertaker to carry out work or choose to supervise the developer's work second section 112 means the undertaken can request the manner in which the seage is constructed for the G General system of drainage reimbursing the developer for the extra cost drainage may be also adopted by Highway Authority Under Highway Act 1980 it is possible by discretionary that the highway drainage becomes part of the building surface water drainage the requirement H2 deals with wastewater treatment systems and sess pools the secretary of state is happy if the systems are of the right capacity to do the job and be seated so not to cause nuisance or health hazards pollute control Waters or water sources or be in flat prown area they should have enough ventilation and not allow groundwater Ingress or allow groundw to overload the system information on maintenance should be available in all service buildings the diic cause of action prior to the specification of the wastewater treatment system is the permission of the environment agency typically as a part of the planning permission process the guidance makes reference to BS 6297 code of practice for the design and installation of drainage fields for use in wastewater treatment for the detailed design of these septic tanks or septic tanks with secondary treatment in drainage Fields Mount or wetlands are typical solutions for one to several dwellings the basic idea is for the solids to settle in the tank and the water to soak into the ground and any bacteria to decompose in the irrated soil package treatment works do what they say on the team same with the septic tanks with secondary treatment but in a compacted version allowing direct discharge to the Water Co economic for larger developments cesspools are just storage vessels for sew so will generally not be permitted unless no other way is feasible now septic tanks need to be positioned at least 7 m away from any habitable parts of buildings and be readily available for emptying meaning not further than 30 m from the vehic AIS for septic tanks with an invert level not Deeper Than 3 m the tank needs to be at least 2.7 cubed meter of capacity under the inlet for four four users and addition 180 L per person tanks can either come from the manufacturer but can also be constructed in engineering brick using 1 in free cmon to sand ration water or 150 mm of thick concrete at least 25 n per mm Square strength ventilation further requirements for the avoidance of settlement or scam disturbance controlling the amount of inflow and access for testing of inflow and outlow as well as for emptying the access for emptying should be secured and durable the information for the type of sewage treatment and maintenance requirements should be fixed within the building a Drainage Field should be at least 10 m away from the Water Co or per permeable drains 50 m away from points of groundwater absor abstraction all Zone one groundwater protection Zone minimum 50 m from any building and away from other drainage features further expectations are put put on the location and quality of the ground conditions and its capacity to soak in water so a percolation test will be required at least three times within at least two within at least two trial holes the design generally follows the spread within perforated pipes over a bed of granular material material similarly with the mount to calculate the floor area of the drainage fields we need to multiply the number of people using the system by the percolation value in seconds per mm divided by four read beds are also a possibility for the secondary or tertiary treatment system and will be and will be of two types either horizontal spreading the water in one plane or vertical allowing the water to permeate evenly through the layer of the re bed the document refers to BR good building guide number 42 for the design and construction of re bed treatment systems in the area of nutrient neutrality influence the Reed beds may be one of only possible alternatives for the development according to the document package treatment works should be in accordance with BS 7781 which is now withdrawn this charge from the plant should be at least 10 m away from water courses or buildings and it should work even in case of a power outage for up to 6 hours at least cpols limits are similar to limits of septic tanks but capacity needs to be much greater at least 18 cubic M for two users with an additional 6.8 cubic meter for every additional person gray water and rainwater storage tanks for reuse in the house should be contained and isolated from the Ingress of groundwater and protect from back flowing of sewage into the tank through the outflow similarly with the previous requirement local authorities and Undertakers have overcharging overreaching rights to make sure the systems are safe and well maintained and our waterways are not polluted it is however an entirely different matter if they are using these rights or not the requirement H3 deals with rainwater drainage for the Secretary of State it is enough to car the water properly away from all the roofs and pav areas making sure the system can be cre of blockages and so it does not damage the foundations of buildings or structures the preference of the outflow given to soak away then water cses then sewers the sizing of the rainwater system will depend on the area of the drained surface and the and Visage rainfall and can follow the prescription of the approved document or to be in line with BN 120 056 Gravity Drainage Systems inside buildings the flat area will be treated as a tributary as it is but inclined planes will have a factor applied to planner area that takes in consideration driving rain so for 30° pitch roof the factor will be 1.29 of the plane area for 45 degree roof the factor is 1.5 and for 60° roof the factor is 1.85 walls are treated as 50% of the elevation areas and walls are considered any PLS inclin more than 70° the sizing of rainwater Goods then follows an assumption of level gutters of half round nature with the max run length at one Outlet of no more than 50 times the water depth G size start at 75 mm and Outlet at 50 mm for the effective area of 6 M squared and end up with 103 mm squ for 150 mm half round G with 89 mm Outlet flow rate 0.38 to 2.16 L per second in between these two sets rainfall intensity can be taken from map for Kent being at Circa 0.02 L per second in other words less than half a teaspoon a second rain waterer pipes can discharge to another gutter or Surface but ideally to a drain or a galley if it drains on the roof or pavement a shoe should divert the water away from the building and and if the discharge is of more than 25 M squared the water should be distributed so as Not to cause a waterfall due to the overflowing gutter of the lower roof Sy syonic roof drainage should be considered using auxiliary standards with special care taken due to possible Downstream S charge and time delay for the syphoning action possibly requiring overflow Arrangement the guidance references use of high hydraulic research limited report Sr 463 as an assistance and directs us to bn1 12056 for further information if drop system is allowed provided due considerations to the effect of falling water and harvesting system when introduced should be clearly marked material for use in rainwater Goods should be suitable water tied and firmly supported but allowed to expand and contract due to temperature changes for pavement drainage up to 4,000 m Square we are directed to the following Guidance the waterfall considered is lower than that for roofs and now in caned at 0.016 l/s per M square around third of the teaspoon the map gives values for different parts of the country the surface should be graded towards outfalls and away from buildings gradient of at least one in 60 in general and Max of one in 40 across a path should be used naturally outside of the simple directions we are guided to bsen 752 whenever possible the paved area should be draining free to perious areas it is being encouraged that a pre perious Paving is used wherever possible the design of such will follow similar consideration to that of soqu if the ground beneath the paving is imperious the granular layer or or cre system can be used as an attenuation tank for more detail we are being sent to Syria c522 report sustainable Urban Drainage Systems designed manual for England and Wales for areas that cannot soak the water in drainage should incorporate GES with appropriate cat pits for seals and position so as to accommodate the settlement of pavement guidance says 5 mm below the pavement the pavement drainage CTS within the document is for the area large ler than 2 hectar that is 20,000 M Square as however is practic practicable Outlets should lead to so way water cause or sewer with the last result in connecting to combined sewer but in any case the capacity needs to fit the combined flow charge the capacity charge is given in the document relevant to the size of the pipe and its gradient contaminated runoff will require separate drainages and the runoff for from petrol stations and car Parks should be provided with oil interceptors Syria report6 INF infiltration drainage Manual of good practice b752 and bread digest 365 sway design are the references for dealing with the infiltration systems but some simple directions are given for small area runoffs in addition swailes infiltration basins filter drains and detention detention pwns are encouraged the requirement H4 deals with building over seers in the gist to satisfy the requirement in the eyes of the Secretary of State the proposed work as of during the construction and as standing cannot damage the existing drainage system or obstruct access to its inspection points theu structure should be so built to not obstruct future replacement Works usually meaning at least 500 mm away from the walls in case of shallow drains moreover the building should not be S susceptible to drainage failures which in practice often means bring bringing the depth of the foundation formation level to that of the drainage system this requirement is valid for building work at 3 m distance from the center line of the drainage drainage is identified on The Undertaker's asset Maps but often when it comes to lateral disposal Mains these are not on maps however the provisions of this guidance will still be valid and gaining the local Undertaker approval for the proposed work necessary the local Undertaker will likely need to confirm the condition of the existing sewer for reasons of possible need for replacement and to make sure the work do not damage the drains the guidance points our attention to theine granular soil which may settle due to the washing away of fine grains into the sewer in case of damage to the drains and groundwater infiltration which will carry these fine particles away we are also reminded of a possible collapse of drains and the impact it may have on our buildings internal inspection Chambers for more than one property are a no no as the access for maintenance needs to be readily a available an alternative external provision approved by the drainage owner typically a local Undertaker would be a way forward a satisfactory diversion possibility needs to be allowed for such that can allow a reconstruction of a sewer without affecting the building the Secretary of State claims free meter of the building to be the right distance and requires mechanical excavator access for drains below 1.5 M deep that could be ex excavated using such machines the guidance limits the length of the build over sewer to 6 M however other agreements can be reached with the owner of the system another 3M limit exists on buildings nearby or overd drainage system that is more than 3 m deep or greater than 225 mm mm in diameter as however speak to the own Fest as other agreements can be agreed on during The Works near all over the drain line should minimize the impact on the drain and piling cannot be done closer than two times the pile diameter of the pile and if the piling takes place within a meter of the drainage sh such should be exposed settlement of the building should be addressed in the drainage construction allowing for differential movements excavation for drain trenches should not undermine existing foundation and if the drain is deep enough according to guidance 2 m to the e invert level then the foundation should form a lentil over the drain with 1 and 1/2 M span either side of the drain and designed so no load is transmitted onto the drain or sewer the requirement H5 deals with separate systems of drainage there's not much here to convey really the foul or great water should not mix with rain water for one the sewage treatment work does not need that extra water from rain and poop floating on our streets due to the flooding is not an ideal scenario the rain can be either soaked in the ground locally or discharge to the local waterways instead when there is work taking place splitting the combined system systems the new development training system should be separate and accommodate the future connection to the separate system to deal with contaminated run of agreement with the local Undertaker needs to be made first the requirement HS 60s with solid waste storage in the Secretary of State opinion as long as the storage is safe and not prejudicial to amenities and agreed with the collection authority to the size and placement the requirement is satisfied a few General points to consider here storage space for storage containers needs to be provided containers of 250 L 0.25 cubic meter capacity per per dwelling per week for domestic developments up to four story access to two separate movable containers in line with the local requirements needs to be provided for separate storage areas per dwelling an area of 1.2 time 1.2 M should be sufficient communal storage areas will require consultations with the local waste collection Authority in high-rise domestic buildings up to four story dwellings can have separate storage areas and the rest can have a shoot fed system in place or another another suitable Arrangement the distance the householder has to travel to get to the storage area should not exceed 30 m horizontally and the waste collectors 25 M for containers up to 250 L up to three steps on the way to the collection Point are allowed and slope should not exceed 1 in 12 external storage areas should be away from wind windows and ventilators preferably in shade and under shelter NH HBC Foundation report nf60 gives some Fair guidance storage enclosur should allow 150 mm movement around the container be ventilated top and bottom on a paved surface and high enough to open the lead for filling minimum 2 m high for communal storage and should be protected from Vermin areas should be washable and capable of receiving po Ed affluent with a trap prolonging sealing in dry periods storage rooms should be separated for recyclable waste storage shoots should be ventilated at least 450 mm in diameter with closed access fitting at each story and its surface should be smooth and non-absorbent we are also told that BS 596 code of practice for Waste Management in buildings is valid alter native approach abiding by the requirement it usually means consultations with the local waste collection authority to establish their requirements and to be on the right side of the Environmental Protection act 1990 especially when the circumstances are more complex and the waste is more hazardous than it than is the typical domestic case so do it right and segregate your waste as required whether you are a homeowner or run a commercial gig [Music] so this is it folks the approved document H drainage and waste disposal let's sum it up the Secretary of State expects that the standards for health and safety are reasonably met this responsibility excludes paragraph H2 which pertains to water contamination prevention ention in summary requirement H4 to H6 emphasizes the importance of not only meeting technical specifications for drainage and waste storage but also ensuring the systems are safe accessible and environmentally sound collaboration with local authorities and adherence to guidance and standards are essential components of compliance requirement H1 for water drainage designs needs to ensure the proper capacity of outflow minimize blockages leaks and flooding and prevent of foul air Ingress into Buildings systems must pass an air tightness test simulating the pressure of at least 38 mm on the water gauge for a minimum of 3 minutes requirement H2 that deals with wastewater treatment system and SES energ systems must be of the right capacity and location to avoid nuisance health hazards and pollution have adequate ventilation and prevention of groundwater Ingress following guidance from the environment agency and adance to BS stus for design and installation is a good idea clear information on maintenance requirements should be available systems must be periodically monitored and maintained to prevent pollution and health risks requirement hre rainwater drainage means that systems must carry water away from roofs and paved areas preference for outflows should be given to soakaways then water courses and lastly sewers correct sizing is based on drainage surface area rainfall expectations and the rate of infiltration system should be simple maintainable and allow for adequate access points for clearing blockages requirement H4 deals with buildings over sewers we need to ensure that new building Works do not adversely affect existing drainage system abstract access for maintenance or create future problems for building stability due to drainage failures an agreement with the owner of the drainage system will be needed requirement H5 separate systems for drainage the drainage of surface water and F water drainage should be kept separate to prevent contamination and facilitate effective drainage management new developments should have separate systems for surface water and fou water drainage surface water should ideally be directed to Sock WS water courses or surface water sewers local Authority approval is required when using combined systems ensuring that public health and environmental standards are met requirement H6 Solid Waste storage is in place to ensure the buildings are provided with adequate facilities for storing Solid Waste before it is collected preventing health hazards and maintaining hygiene building must have suitable and sufficient space for storing waste containers beans bags Etc based on the building size and use waste storage areas must be easily accessible for both occupants and waste collectors storage areas should be located to prevent health hazards and nuisance ensuring they are not placed too close to habitable areas wa storage facilities should be designed to be verment proof and weather resistant adequate ventilation and cleaniness must be ensured to prevent unpleasant orders and past infestation in the next episode we will move to approve document J combustion appliances and fuel storage [Music] system I hope you enjoyed this episode and that the consideration of the approved document hedge drain and W waste disposal makes more sense to you it's been a long one but I decided not to split this one in Parts I think in this in this circumstance it's better to have it all in one place if you have any questions reach out to me on LinkedIn or send me an email I am more than happy to help you out in BNA we deal with planning designing and managing of your projects and we are always glad to facilitate a free initial consultation to steer you in the right Direction visit www.b now.co and reach out to us whether your question is if we can help you with your project or what should I do we will be able to give you a piece of non obligatory advice at bitna we help our clients design and execute their dream homes or Investments if your building is falling apart we can also help investigate the reasons behind it and to provide you an appropriate strategy design and specifications for the repair thank you again for listening please voice up your opinions I'm waiting for you on LinkedIn and I want to hear from you see you next week but remember Bytnar Designs The World Around You, Toodloo!
Piotr Bytnar BEng (Hons) MSc CEng MIStructE
Chartered Structural Engineer who deals with the Architecture of buildings. His Master's Studies led him to an in-depth understanding of risk and contract arrangements in construction as well as specialist knowledge in soil mechanics.
He and his team help homeowners and property developers to design and deliver construction projects reducing waste in time and the cost. He believes that the construction project is an iterative process that can be well managed and it is best managed if all the aspects of the project definition and management are dealt with in-house or coordinated by one organisation. His team works to all stages of RIBA and ISTRUCTE stages of work and enables contractors to deliver projects on-site providing risk evaluations, methodologies for execution of works and temporary works designs.
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