Dr Ivan Stoianov, water systems engineering expert from Imperial College, provides technical evidence on water provision and use during the Grenfell fire. His analysis reveals critical failures in water flow rates to firefighting equipment.
00:00:29 good morning everyone welcome to today's hearing uh today we're going to hear some expert evidence on the provision of water uh for firefighting purposes yes mr
00:00:40 uh for firefighting purposes yes mr clear so my call dr ivan stoyanov thank you
00:00:52 good morning dr stone enough i gather you're going to take the eggs is that right that's right there should be a testament there would you take it in your right hand please and read the words on the screen thank you i swear by
00:01:04 words on the screen thank you i swear by almighty god that the evidence i shall give shall be the truth the whole truth and nothing but the truth thank you very much and please sit down and make yourself comfortable thank you
00:01:18 all right yes mr cleveland thanks sir would you please confirm your name for the record yes my full name is yvonne the jordan to janov
00:01:26 janov good morning dr estellanov thank you very much for attending to give evidence this morning it's much appreciated now my questions are intended to be short and simple sometimes it doesn't
00:01:37 short and simple sometimes it doesn't play out that way if they are in any way unclear please say so and i'll rephrase them
00:01:42 them secondly if at any stage during the giving of your evidence you require a break please say so that's not a problem and thirdly could you please remember that the stenographer is trying to
00:01:53 that the stenographer is trying to capture everything you say and everything you say accurately so if you could
00:01:57 could go at her pace that would be much appreciated and also please where you mean to indicate yes or no say yes or no rather than nod or shake your head as the case may be
00:02:09 shake your head as the case may be now you've provided two reports to the inquiry uh your report entitled the provision and use of water for firefighting the fire for fighting the fire at grenfell tower on the 14th of
00:02:21 fire at grenfell tower on the 14th of june 2017
00:02:23 june 2017 dated the 20th of july 2021 can be found at is trp quadruple zero trouble zero one
00:02:34 is that your report that's correct yes and you provided a supplementary report dated the 29th of march 2022 which can be found at i s t r p s
00:02:45 which can be found at i s t r p s quadruple zero treble zero one yes correct and that's your supplemental report yes uh can you confirm that the facts and matters set out in those two reports are
00:02:57 matters set out in those two reports are true to the best of your knowledge and belief yes i confirm so and is it correct that you've provided the reports in the same way that you would have provided an expert report to a court yes correct
00:03:10 a court yes correct and do your report set out your opinions on the matters that are relevant to this inquiry
00:03:15 inquiry yes correct now if we can go to i s t r p quadruple zero treble zero one forward slash six
00:03:28 uh we see here at section 1.2 you set out your expertise if i could briefly just go through some of those matters
00:03:37 matters first of all you hold a diploma a batch of engineering and an msc in civil engineering from the faculty of hydrotechnics at the university of architecture civil engineering and
00:03:49 architecture civil engineering and geodesy in sofia bulgaria and those degrees were awarded in 1995 is that right that's correct and in 1998 you're awarded an msc in environmental
00:04:01 you're awarded an msc in environmental engineering by the imperial college of science technology medicine here in london is that right correct and in 2003 you were awarded a phd in civil and
00:04:12 you were awarded a phd in civil and environmental engineering by imperial college is that also right correct can you help us what was the subject of your doctoral research my work was very much focused on
00:04:24 my work was very much focused on a phenomena in water supply networks known as pressure transients so the the work was based on
00:04:33 based on mathematical modelling of these phenomena and also an extensive experimental work and part of that work was
00:04:40 was in collaboration with them's water at the time thank you is it right that you are currently a reader in water systems engineering at imperial and you hold a five-year fellowship in water systems engineering
00:04:52 fellowship in water systems engineering from the engineering and physical sciences research council correct now if we look at the bottom of page 6 at line 28 you say that your expertise covers four
00:05:05 you say that your expertise covers four things and i quote first the design operation and control of water distribution systems two applied and fundamental research in the hydraulic modeling pressure control
00:05:16 the hydraulic modeling pressure control and optimization methods for water distribution networks three pressure transients analysis in water distribution networks and turning over the page four
00:05:27 four experimental research in water distribution networks that combines laboratory experiments and field studies in complex networks is that a first summary of your expertise yes it is
00:05:39 summary of your expertise yes it is you also lead a research group at imperial called infrasense labs that's i-n-f-r-a-s-e-n-s-e
00:05:48 labs which you founded in 2009 which focuses on the design optimization and control of water supply networks is that right that's right am i right that you have no expertise in
00:06:00 am i right that you have no expertise in relation to firefighting emergency planning or instant response correct thank you
00:06:07 thank you now if we could go to i s t r p quadruple zero trouble zero one forward slash five
00:06:18 we see midway down the page at line 13 section 1.1.2 where we find the heading my instructions there you describe the questions which
00:06:29 there you describe the questions which you are asked to address in your report and i'll read them into the record so that they are known to everyone one how much water did london fire brigade lfb used during the
00:06:40 london fire brigade lfb used during the grenfell tower fire both internally and externally including a the type of equipment available the flow rate needed for optimal operation of each piece of equipment and the
00:06:51 each piece of equipment and the difficulties encountered in achieving the necessary flow rate b the number of water jets c their time of use d the duration of use
00:07:02 d the duration of use two what were the locations of fire hydrants from which lfb supplied water for fire fighting their flow rate excuse me discharge characteristics and conditions
00:07:13 conditions excuse me were there alternative water sources that might have been utilized by lfb
00:07:18 lfb three based on evidence gathered in the context of questions one and two and using simulations created using that evidence what was the water flow and pressure in thames water
00:07:29 pressure in thames water twul's water supply network on the
00:07:33 on the night of the 14th of june 2017 was operational pressure consistent with the minimum pressure requirements four what was the response of twul and was it effective is that a complete
00:07:46 was it effective is that a complete summary of your instructions yes it is your supplementary report addresses two particular matters first your understanding of a meaning of a british standards document referred to
00:07:58 a british standards document referred to in your main report and secondly the conclusions of an lfb report testing some of its equipment in broad terms is that right that's right now it's clear from these instructions
00:08:11 now it's clear from these instructions and it will become clear throughout your evidence that your report inevitably touches upon actions taken by and decisions made by the lfb on the 14th of june 2017. is it right that while your report
00:08:22 is it right that while your report comments and draws conclusions about the brigade's actions from a water or hydraulic perspective you do not seek to draw conclusions on matters of operational firefighting or strategy as
00:08:33 operational firefighting or strategy as these are outside your expertise and so outside the scope of your instructions that is correct i i made observations uh but uh as you as you pointed out these
00:08:44 but uh as you as you pointed out these observations are by no means conclusions on on the necessary actions for firefighting could we go to ist rp quadruple zero trouble zero two forward
00:08:55 quadruple zero trouble zero two forward slash five and line twenty four
00:09:04 you see there you say this where relevant to my instructions investigation conclusions i have commented on the actions and statements of a number of individuals including lfe firefighters and officers
00:09:16 including lfe firefighters and officers network service technicians and other twul employees none of this analysis is intended nor should it be taken as personal criticism of the individuals concerned i have no
00:09:28 of the individuals concerned i have no doubt that they acted to the best of their ability in extremely difficult circumstances on 14th of june 2017. am i right in understanding that's a point you'd particularly wish to emphasize before starting your evidence
00:09:40 emphasize before starting your evidence that that's correct
00:09:44 could we stay
00:09:47 stay on this page and we see in section 2.2 at the foot you summarize there the various materials that you relied upon for the purposes of producing your report
00:10:00 purposes of producing your report i won't go through everything but is it right to say that the materials identified in section 2.2 which starts at page five and goes over to page six um is the accurate summary
00:10:11 to page six um is the accurate summary of the evidence you've considered in reaching the conclusion set out in your report
00:10:16 report yes it is
00:10:19 now those preliminaries are dealt with uh dr stonoff can i turn to deal with some basics that we probably need to establish before we turn to more of the detail and
00:10:30 before we turn to more of the detail and the first element of the basics i'd like to discuss with you today is the water distribution network itself yes now um if we can go to i s t r p
00:10:41 yes now um if we can go to i s t r p quadruple zero treble zero three forward slash five
00:10:50 now in this chapter in broad terms you describe the water distribution network and its functions now in summary is the water distribution system a complex network of pipes and
00:11:03 system a complex network of pipes and valves used to transport water from storage such as reservoirs and water towers to customers and hydrants either by force of gravity and or with the assistance of pumps
00:11:15 assistance of pumps yes it is it is a complex system and the emphasis on the word complex correct
00:11:20 correct and system as well secondly the water distribution network's purpose is to provide water in an appropriate quantity at the appropriate pressure and of the
00:11:31 appropriate pressure and of the appropriate quality with mineral water leakage is that again a fair summary of its purpose uh we yes absolutely with a slight correction at minimum cost clearly leakage is part of these
00:11:43 clearly leakage is part of these components of wastage we are trying to minimize but generally the provision of these key variables needs to be done at minimum cost and finally your report refers variously
00:11:54 and finally your report refers variously to the water distribution network to the water distribution system and to the water supply system am i right in understanding those to be interchangeable terms meaning the same
00:12:05 interchangeable terms meaning the same thing
00:12:06 thing not not entirely because we have a certain hierarchical structure within these systems these systems include the bulk transmission of water for example from
00:12:17 transmission of water for example from reservoirs to treatment works to [Music]
00:12:21 [Music] certain kind of service reservoirs we call this water transmission network we then from the water transmission networks the the pipes go into the streets to to deliver
00:12:32 streets to to deliver water to individual customers so this is what we refer generally as water distribution and then we have the supply pumps which goes to the to the individual customers so water supply system is the overarching term which
00:12:45 system is the overarching term which combines both the transmission and the distribution thank you now
00:12:50 now in this chapter of your report but go to page eight
00:12:56 and we see at the top of that page figure 3-2 and in broad terms this illustrates how water is delivered from the water distribution system to a
00:13:07 from the water distribution system to a fire brigade during a fire in broad terms is that a correct summary yes it is
00:13:13 yes it is now if we can first identify the various components of this diagram the blue
00:13:19 the blue symbol to the left is a water tank or reservoir i.e the water source is that right
00:13:25 right correct and the water source could also be a pumping station is that right that's right the blue lines represent the water pipes or mains is that right that's right
00:13:37 or mains is that right that's right the black symbol with a red dot at its center is a fire hydrant correct we can see the red pumping appliance which
00:13:45 which people would ordinarily know as the fire engine is that right that's right and to the top right we can see a building a building with a
00:13:56 a building with a dry rising main through which water is made available for internal fire fighting is that right that's right and finally we can see in the bottom right
00:14:06 right a firefighter holding a handheld firefighting jet which is known as a branch is that right correct
00:14:12 correct now again this is an example and you might instead have depicted for example an aerial appliance or a ground monitor which we'll come on to discuss later in your evidence
00:14:24 to discuss later in your evidence absolutely the purpose of this diagram schematic was very very broad just to highlight the different uh uh appliances and as you said branches can be fed
00:14:35 and as you said branches can be fed from the pump appliance thank you now in simple terms and apologies if if this is too simplistic water travels from the source through the system of pipes to a hydrant
00:14:46 the system of pipes to a hydrant the fire brigade can then use hoses to supply water from the hydrant to that pumping appliance from which the water can then be pumped on through further hoses to fire fighting equipment is that
00:14:57 hoses to fire fighting equipment is that a fair summary correct now you describe the water distribution network at grenfell in chapter six of your principal report um for that
00:15:08 your principal report um for that purpose could we go to r istrp quadruple zero treble zero eight forward slash eight and look at line seventeen
00:15:20 now there you say this grenfell tower is located within the barrow hill zone which is part of the london water resources zone operated by
00:15:31 london water resources zone operated by thames water utilities limited twul twul is the statutory water undertaker for a large geographic region which
00:15:41 which includes the whole of central and greater london first of all does that remain a correct summary that's right now if we can stay in this chapter but go to page 10.
00:15:55 we can see there in the top part of that page
00:15:59 page you list five sources of water which can supply water to the barrow hill zone in which the tower was found
00:16:08 was found we have the barrow hill reservoir the wilsdon reservoir the hammersmith pumping station the holland park shaft and the barrow hill shaft
00:16:19 hill shaft now is it right that the two reservoirs supply water by gravity in other words they store water at a higher altitude than the buildings and customers they supply so there is no pumping
00:16:30 supply so there is no pumping arrangement required yes
00:16:34 yes the setup is a little bit more complex and i have another figure which explains this the way this setup operates is in that particular system is uh water is pumped from uh our pumping stations in
00:16:48 pumped from uh our pumping stations in uh hammersmith uh from there it supplies water during the day uh both in terms of a very well large set of water transmission mains and distribution mains and during
00:17:00 and distribution mains and during periods of low demands the reservoir balances that supply and demand so it could be that sometimes it's pumped water so it's pressurized it could be that at nighttime when the
00:17:12 could be that at nighttime when the pumps are turned off then the actual water from the reservoirs is fed by gravity into the same distribution networks so there is this notion of flow reversals across this water transmission maze depends on balancing to get that
00:17:25 maze depends on balancing to get that supply and demand apologies again i may be making matters too crudely simple but in essence the hammersmith pumping station the holland park shaft and the barrow hill
00:17:36 holland park shaft and the barrow hill shaft supply water by pumping it from the thames water ring main is that essentially correct yes and again a slight sort of
00:17:47 yes and again a slight sort of distinction here i know these are small technical details probably but uh the actual hammersmith pumping station can feed water from the london ring main but equally directly through a set of transmission mains from the pumping
00:17:59 transmission mains from the pumping station in the west of london now could i turn on to the three key factors for the provision of water for fire fighting and to that end could we go to is trp quadruple zero trouble zero
00:18:13 go to is trp quadruple zero trouble zero three forward slash seventeen
00:18:19 and we can see at section three point one point four uh you say that from a hydraulic perspective there are three key factors which affect the provision of water for firefighting
00:18:32 the provision of water for firefighting is it right that you include the qualification from a hydraulic perspective because there may well be other factors outside your knowledge and expertise which are relevant for a fire service from an operational perspective
00:18:45 from an operational perspective correct
00:18:46 correct whereas here you focus strictly on the physical requirements for the supply of water is that right that's right yes there are other factors which as you as you highlight it is beyond the hydraulic
00:18:57 you highlight it is beyond the hydraulic control thank you now the first key factor you identify for this purpose is at point one and it is the available quantity of water
00:19:07 water put bluntly the amount of water that is stored in tanks or elevated reservoirs within the water distribution network accessible through hydrants again essentially is that correct that's right
00:19:19 essentially is that correct that's right now you've mentioned water from tanks and reservoirs here but presumably that would also include water available from pumping stations that's right i mean it's uh it's a
00:19:31 that's right i mean it's uh it's a complex system of all these storage uh facilities such as reservoirs service reservoirs etc but equally they're they're supplied by uh pumping stations
00:19:42 they're supplied by uh pumping stations treatment works etc so it's part of this large complex system and
00:19:47 and again at its simplest in relation to the water distribution system at grenfell this would include water available from all the sources we've been discussing barrow hill and wilson reservoirs
00:19:58 barrow hill and wilson reservoirs hammersmith pumping station on the holland park and barrow hill shafts is that right that's right and is it right that the available quantity of water is fundamental because
00:20:09 quantity of water is fundamental because in plain terms if there's not enough water
00:20:12 water available that diminishes the adequacy of firefighting efforts that's right it's one of the components is the availability clearly as we see there is other components
00:20:23 as we see there is other components later probably in the discussion but yeah availability is number one when we're talking about quantity available here are we really looking at the total volume of water in the system
00:20:34 the total volume of water in the system so so generally we um we try to
00:20:38 we try to satisfy particular physical laws and this physical laws for us is the conservation of mass so i need to have a certain volume of water which i need to use the second question is can i use it
00:20:49 use the second question is can i use it at the right time at the right place but it's far as the storage is concerned that system had infinitely larger storage than it was required for firefighting well that's
00:21:01 required for firefighting well that's rather what i had in mind but all right well you've explained that thank you very much now the second key factor that we've identified there at point two on page 17 is the water flow rate delivered from
00:21:13 is the water flow rate delivered from fire hydrants to pump appliances now in layman's terms when we talk about flow rate from a hydrant
00:21:20 hydrant we're referring to how much and how quickly that hydrant can supply water to the pump appliance is that right correct and if we stay
00:21:32 on page 17 you highlight three particular things to which on which the flow rate from a hydrant to a pump appliance depends and we can see little a starting at line 17
00:21:44 we can see little a starting at line 17 there
00:21:45 there first of all the water pressure in the pipe which supplies the hydrant can you help us what is the difference between water flow rate and water pressure
00:21:55 pressure well these are fundamentally different variables
00:21:59 variables so pressure in our case this is the force which the water would apply on the pipe wall
00:22:05 pipe wall and
00:22:06 and that force we we generally we define as as as water pressure we can express water pressure in different terms in different units uh flow rate will be the volume of water going across
00:22:19 will be the volume of water going across a section over a certain period of time so if i
00:22:22 so if i uh in a very simplistic term if i open pres a tap at home to have a shower the flow rate will be let's say 100 liters per minute or so uh and and that is the
00:22:33 per minute or so uh and and that is the the kind of the volumetric flow going over particular time over that particular cross section so these are two fundamentally different variables well presumably you can have
00:22:44 variables well presumably you can have a high pressure and the very low flow rate as when you puncture a garden hose
00:22:52 let me explain with these bottle for example if i squeeze this bottle i will increase the pressure into the bottle if i have a very tiny hole into that bottle i will get a very little flow rate
00:23:03 i will get a very little flow rate irrespective of how much i squeeze this so the actual flow discharge whether it's through a fire hydrant whether it's through a branch whether it's through a leak they're all governed by the same
00:23:15 leak they're all governed by the same physical phenomena which is discharged through an orifice and that discharge to an orifice depends on the characteristic the discharge characteristics of the authorities and the differential
00:23:26 authorities and the differential pressure so in other words if i'm discharging to the atmosphere that will depend at the pressured inlet to that nozzle or pipe or fire hydrants etc thank you thank you i believe the top
00:23:38 thank you thank you i believe the top was on your bottle as you demonstrated yeah i made sure that that's the case um the higher the water pressure and the pipe serving the hydrant the higher the flow rate from the
00:23:49 the higher the flow rate from the hydrant is that too simple or is it for present purposes correct um it is correct the second point to identify point 2 b line 19
00:24:00 line 19 is the flow coefficient of the hydrant we'll return to flow coefficients in detail later on but in layman's terms is it right to say that a hydrant's flow
00:24:11 it right to say that a hydrant's flow coefficient is a measure of how great a flow rate the hydrant can provide given the pressure of water it receives correct this is very much as i just mentioned about this fundamental
00:24:22 mentioned about this fundamental principles of flow discharge through an orifice it depends on the characteristics of this orifice which in this case will be expressed by the flow coefficient and uh and the differential
00:24:33 coefficient and uh and the differential pressure across that orifice and again just as a fl flow from that point forward a bit of phrase the flow coefficient is important because if a hydrogen has a very low
00:24:44 because if a hydrogen has a very low flow coefficient and even if it is provided with good water pressure it will provide a low water rate in essence is that right that is correct i mean if you look at the flow
00:24:55 the flow discharge
00:24:57 discharge across an orifice we would have this kind of flow coefficient multiplied by the square root of this differential pressure or the pressure that means that in very simple mathematical terms if i
00:25:10 in very simple mathematical terms if i increase the pressure twice that will be the square root of this number two which would be sorry gives me 40 increase in the flow rate across that orifice so consequently
00:25:21 consequently the flow coefficient is a very key part for me to reach the final objective reaching particular discharge across that hydrant or a branch or whatever thank you
00:25:32 a branch or whatever thank you and the third point we see at point c at line 21 is the energy or pressure losses between the hydrant and the pump appliance and pressure losses can be caused
00:25:42 caused for example by kinked hoses due to increased friction is that right correct i mean the other phenomena as i earlier stated you know water is uh water in a conduit or a flow in a
00:25:53 water in a conduit or a flow in a conduit will be governed by certain physical laws and part of it is this kind of a notion of pressure loss or pressure head loss uh that that is due to a lot to to do with the conditions of
00:26:06 to a lot to to do with the conditions of the pipe and the conduit uh there will be a lot to do with a certain additional uh turbulence that might be occurring so in the example we just highlight it is for example king causes or even causes
00:26:17 for example king causes or even causes with a lot of a larger length with a lot of interconnections couplings that can introduce additional hat loss into that particular system
00:26:28 hat loss into that particular system thank you and if we could stay in this chapter but go to page 20
00:26:35 at the top of the page at section 3.2.5 you explain the concept of continuity of flow
00:26:42 flow in lay terms the flow rate delivered from the hydrant to the pump appliance is important because if it is not high enough to maintain continuity of flow the pump's tank will gradually empty
00:26:53 the pump's tank will gradually empty which means that the water supply to firefighting equipment will be paused whilst waiting for the tank to refill again is that a fair summary yes i mean water is not compressible so as a result of that whatever we get into
00:27:05 as a result of that whatever we get into that tank that's the same volume we'll we'll be able to get out of that tank and and the actual pump appliance has a storage tank which is not very large it's only about
00:27:16 it's only about roughly 1.4 cubic meters of water so it's about 1 400 liters storage capacity and you have to balance whatever comes into that tank needs to be equal or
00:27:27 into that tank needs to be equal or greater to whatever comes out of that tank which goes through the centrifugal pump installed on the pump appliance thank you if we go back to page 17
00:27:39 and we see at line 25 the third key factor that you identify which is the provision of water for fire firefighting is the flow and rate sorry is the flow rate and pressure at the
00:27:52 is the flow rate and pressure at the branch nozzle monitor error appliance or dry rising main again in simple terms that means the flow rate and pressure at the end piece the firefighting equipment in
00:28:03 piece the firefighting equipment in other words whatever it is that actually projects the jet of water is that right that's right and the higher the pressure and the higher the flow rate of the water going
00:28:14 higher the flow rate of the water going into a piece of equipment the higher the volume and or distance of water it can project again in its basics is that right
00:28:21 right it is i mean the water jet ultimately we need to we need to kind of transform certain kinetic energy into that water jets and that kinetic energy will be a function of the mass the volumetric
00:28:32 function of the mass the volumetric muscle over certain confined volume and equally the velocity of that flow rate so that's why any any forms of branch or nozzle has this optimal operational
00:28:44 nozzle has this optimal operational specifications and this operational specification takes this
00:28:49 this trade-off between safety safe operation of that nozzle and equally maximizing flow rate and reach of that of the of the jet projected from that nurse thank you i now want to turn to the second
00:29:01 you i now want to turn to the second part um of the examination today which is water deployment on the 14th of june 2017.
00:29:07 2017. now this
00:29:09 now this subject is addressed in chapter 5 of your report where you set out a detailed chronology of the deployment of water jets at grenfell tower from the first arrival of
00:29:21 grenfell tower from the first arrival of lfb cruise at 0 0 59 to approximately 1 o'clock in the afternoon is that right that's right now if we can go to istrp quadruple zero
00:29:32 quadruple zero treble zero six forward slash three
00:29:42 now here you explain that your report identifies first of all paragraph 1a the equipment used and available to lfb to project those jets secondly at paragraph 1b
00:29:56 those jets secondly at paragraph 1b the timing duration of their use along with their estimated vertical reach thirdly at paragraph 1c the location and status of the hydrants and pump appliances used to supply the water
00:30:09 appliances used to supply the water d
00:30:09 d at paragraph two the utilization of the equipment in relation to their rated water pressure and flow rate now looking at paragraph two
00:30:21 now looking at paragraph two you say here from the end of the second line this
00:30:25 line this rated water flow rate or rated pressure is the maximum flow rate or pressure for which a branch a monitor nozzle and the complete water supply setup
00:30:38 and the complete water supply setup a pump appliance fire hoses fittings and a branch or a monitor can be safely operated
00:30:44 operated is that correct that's right so put in layman's terms each piece of equipment will have a pressure rating and a flow rating which describe the maximum water pressure and the maximum
00:30:57 maximum water pressure and the maximum flow rate which the equipment can be safely used is that right in its essentials it is right because that balances the the notion of the effective maximum effectiveness of the use of that
00:31:08 effectiveness of the use of that equipment and its safe operation where do the rated pressure and flow figures come from what's the source of that information so generally that the source of that
00:31:20 so generally that the source of that information is based on the manufacturer's specifications ultimately the manufacturer is their obligation to be able to
00:31:29 able to identify through testing and validation uh the balance of these trade-offs and and that and probably there will be some safety factors so in other words uh these figures might not fully represent
00:31:41 these figures might not fully represent the actual capabilities of this equipment because they they need to allocate for some unsafe potential use of that equipment and
00:31:50 and that safety factors take into account that particular conditions is it right that the rated flow of pressure figures are also sometimes referred to as the nominal or optimal
00:32:01 referred to as the nominal or optimal flow or pressure figures that's the general uh using in the engineering language and
00:32:11 kind of applications but i have not been able to identify that into the lfb documents
00:32:17 documents now in your report you calculate the utilization rate of firefighting equipment by comparing the flow rate that the equipment received on the night with its rated flow figure is that right
00:32:29 with its rated flow figure is that right correct so i i strongly believe in this sort of notion of cumulative gains so in other words if you want to the the final outcome which is to project water jets at its maximum reach
00:32:42 project water jets at its maximum reach and its maximum flow rate because that will be the best chance to offset particular heat release rate that means that that equipment needs to be operated as close as possible to these specified
00:32:54 as close as possible to these specified rated values so just giving a practical example in layman's terms of the point you've made if a particular piece of firefighting equipment brunch had a rated flow of say
00:33:06 equipment brunch had a rated flow of say a thousand liters per minute but received an actual flow rate of 500 liters per minute you would describe that handheld branch as being 50 utilized or as having received 50 of its
00:33:19 utilized or as having received 50 of its rated flow is that a practical example of what you're the point you're making it is because that will have ultimately the impact on the reach which that water jets can
00:33:30 jets can can reach and equally uh it will have an impact on the ability to stop certain heat flux occurring on a particular ignited surface
00:33:41 particular ignited surface now if we can go back to the page on the screen which is page 3 and we see at line 22 paragraph 3 you there identified difficulties encountered in supplying water for
00:33:52 encountered in supplying water for firefighting from the water distribution network and finally a paragraph four you deal with alternative water supply sources that might have been used by the
00:34:03 sources that might have been used by the lfb
00:34:04 lfb is that a fair summary of the structure of chapter five um that's right search in chapter five i try to
00:34:11 try to uh systematically look at the utilization of water jets as a first instance so we i had access to a number of visuals sorry to introduce yeah we'll
00:34:22 visuals sorry to introduce yeah we'll come on to that but apologize really inviting you just to confirm that was the structure i confirmed yes okay and if we can go to um istrp quadruple zero trouble zero six forward
00:34:34 quadruple zero trouble zero six forward slash four which over the page
00:34:40 uh the report uh states and i think this is the point you were coming on to um the evidence presented in this chapter has been gathered from sources including witness statements video footage
00:34:51 witness statements video footage provided by the national police air service video footage from body worn cameras provided by the metropolitan police service and other sources as referenced in the report is that a first
00:35:03 referenced in the report is that a first summary of the materials you've relied upon
00:35:05 upon correct and that material provides very high granularity in terms of time on the utilization of the world now you refer to other sources in addition to those listed here those other sources include documents
00:35:17 those other sources include documents disclosure from the lfb and from manufacturers relating to firefighting equipment is that right correct and you also refer to evidence given by firefighters during phase one of this
00:35:28 firefighters during phase one of this inquiry is that right correct and is it right that there are also some limited instances where you've relied upon photographs of the tower taken by members of the public or press
00:35:40 members of the public or press on the day of the fire during and which have been published online correct now taking those sources together with those listed at the top of
00:35:51 those listed at the top of page four of chapter five does that represent a comprehensive summary of all the sources you reviewed for these purposes it does now if we can go
00:36:02 now if we can go to stay in this chapter but go to page 7
00:36:08 we can see starting at line 16 onwards you list the external jets which you've labeled jets a through to j which were deployed by the lfb on the
00:36:20 which were deployed by the lfb on the 14th of june from the first arrival of the brigade until about one o'clock in the afternoon is that right that's correct now what i'll do dr stone off i'll go through each of these jets uh with you okay
00:36:33 each of these jets uh with you okay first of all jet a which was a handheld branch on the east side of the tower which was first projected at 0 1 15 hours now a handheld branch has simply won
00:36:46 now a handheld branch has simply won what one
00:36:47 what one might describe as a handheld firefighting hose is that right that's right now we can see an example in your report of
00:36:56 of handheld branches used and before we look at that i should say that there is a trigger warning for people in the room and who are watching we're about to see some still images which
00:37:07 about to see some still images which show the file and exterior of the tower so anybody who feels uncomfortable about that should take steps to leave the room or the live stream now or otherwise protect themselves i will wait a few
00:37:18 protect themselves i will wait a few moments to allow people to do that if needed
00:37:25 so if we can go to figure 5-17 on page
00:37:29 on page 27 of this chapter which is page 37 with the opus reference we can see in figure c there is a green oval
00:37:42 there is a green oval symbol at the bottom right of that and that is a photograph of a handheld branch being held by two firefighters is that right correct
00:37:52 and this is what you refer to as jet a correct
00:37:57 correct if we can turn over the page to page 38 we find figure 5 19
00:38:05 19 which is the second set of images on that page and here we see three types of handheld branch used by the brigade is that right correct the video and any evidence i've
00:38:16 correct the video and any evidence i've i have come across very much in the case the first two branches i have not seen any
00:38:22 any any
00:38:23 any evidence that the third one delta attack 400 s pro has been used thank you now if we could go back to page seven and the list of jets you helpfully provided
00:38:36 we see it little b at line 17 jet b
00:38:40 jet b which you describe as the alpha 2 1 3 turntable ladder east was utilized continuously between 0 147 hours and 0 205 hours
00:38:52 hours and 0 205 hours with about 60 percent of its rated water flow of 2 000 liters per minute now am i right in understanding that this was the first of the three aerial
00:39:03 this was the first of the three aerial appliances deployed by the lfb at grenfell
00:39:06 grenfell uh correct again we need to be careful uh by stating three because at the secondary appliance 8245 actually was never deployed as a uh the monitor of
00:39:18 never deployed as a uh the monitor of that radio appliance was not deployed there was a high pressure hose uh stuck to that particular appliance so so just to
00:39:26 to just for the kind of be very accurate with that statement i would say out of the probably two deployed a lot of platforms
00:39:35 platforms now
00:39:36 now again just dealing with basics aerial appliances are fire engines with a ladder or a cage which is capable of being extended is that right correct now you noted here that alpha 213
00:39:47 now you noted here that alpha 213 received only approximately 60 percent of its rated flow we'll come on to that later but i just want to put a place marker for that particular point here now next jet c
00:39:59 next jet c which you describe as a ground monitor on grenfell walk which you note is to the south and east of the tower which was used intermittently between to 41 hours 11 30 hours
00:40:12 to 41 hours 11 30 hours now just looking at basics for these purposes at the moment dr stonov a ground monitor is a water nozzle which sits in a frame enabling it to be placed on the ground and aimed in a particular
00:40:24 on the ground and aimed in a particular direction without the need for firefighters to hold it as if they were holding a normal firefighting branch is that an accurate description correct and we can see
00:40:35 and we can see an illustration of a ground monitor to remind people which is at page 21 in this chapter at figure 5.6
00:40:45 thank you and that's what we're referring to here yes just for clarity that ground monitor can be used with different nozzles and that sort of figure also indicates the use of these different nozzles one of
00:40:57 use of these different nozzles one of them is the mercury adjustable flow nozzle and the other one is the plain deluge tip or what we refer normally is a smooth ball thank you awesome could we go back to page seven
00:41:12 and if we could look at little d which is at line 22 you identify jet d d for delta and you describe it thus
00:41:24 and you describe it thus alpha 245 aerial ladder platform on the east side of the tower was utilized for less than one minute at zero to 13 hours and then continuously
00:41:35 zero to 13 hours and then continuously between 0 3 28 hours and 0 9 45 hours with a pause between 0 6 57 hours and 0 7 14 hours aerial ladder platform or alp 245
00:41:49 aerial ladder platform or alp 245 was i think the second of the three aerial appliances deployed and if you could bear with me in saying there were three deployed just for the sake of clarity and establishing basics first before going into detail
00:42:00 before going into detail is that right uh correct now at the bottom of page seven uh paragraph one e says this jet e
00:42:09 jet e which was sierra one three alpha one the surrey aerial ladder platform on the east side of the tower was utilized after 10 47 hours
00:42:20 after 10 47 hours now jet e
00:42:21 now jet e is i think another aerial appliance which you refer to as the surrey aerial appliance is that right correct and if we turn over the page to page eight
00:42:32 line three we have jets as in the plural f multiple handheld branches for extinguishing burning debris on the east side utilized intermittently
00:42:45 side utilized intermittently and here again apologies for asking you about what may be the obvious but burning debris refers to ignited material that was falling from the tower to the ground is that right that's right and so these jets were aimed not at the
00:42:57 and so these jets were aimed not at the tower as such but burning debris on the ground surrounding the tower is that right correct we have next jet g a handheld branch for burning debris on
00:43:08 a handheld branch for burning debris on the south side we then have going down at the page to line 11 jet h a covering water jet from a handheld branch
00:43:19 water jet from a handheld branch initially which was later sometime after zero five hours 100 hours replaced with a grand monitor north west corner the water jet was projected intermittently between approximately 0
00:43:32 intermittently between approximately 0 to 43 hours and 10 52 hours can you help us hear what do you mean by a water by a covering water jet um so uh that that's a water jet which
00:43:45 um so uh that that's a water jet which was projected from the ground monitor onto the tower um and that specific one it's the waterjets on the northwest corner
00:43:56 the waterjets on the northwest corner and next jet eye which is dealt with at 9 15 a covering water jet from a handheld branch west side the water jet was projected intermittently between
00:44:08 was projected intermittently between about zero to 45 hours and zero three 45 hours is that right correct and finally jet j a covering water jet from a handheld branch west side again the
00:44:19 handheld branch west side again the water jet was projected intermittently between zero three twenty hours and ten fifty two hours is that
00:44:26 is that all the jets that you've identified for the purpose of the report correct and and just to say i i believe i have high confidence into that list based on the
00:44:37 confidence into that list based on the very high granularity of the of the visual data which uh was provided to me now these 10 jets a through to j describe all of the external water jets
00:44:49 describe all of the external water jets deployed at grenfell from the start of the fire until about one in the afternoon is that right correct and just going back to basics so we know what we're dealing with in this chapter this chapter also describes the supply
00:45:00 this chapter also describes the supply of water to the dry rising main as we can see at page eight point k
00:45:07 point k a hose you refer to as supply k which was also used to supply water to the inside of the tower is it right though that the focus of your analysis is water jets deployed to the exterior
00:45:19 is water jets deployed to the exterior of the tower uh great um so
00:45:23 so supply k i think we have to uh this was particular emphasis was the north and west sides of grenfell tower uh clearly the supply of the dry riser main was
00:45:34 the supply of the dry riser main was done uh through the south side where the actual breaching valve was placed so that's not explicitly mentioned into this list
00:45:45 this list now each of the jets deployed at grenfell whether a handheld branch a grand monitor or aerial appliance was supplied by a pump appliance is that right correct now we don't need to go to
00:45:56 right correct now we don't need to go to them but at pages 10 through to 11 of this chapter you identify the six pump appliances which were used to
00:46:05 to supply the jets deployed and they were pumped
00:46:08 pumped golf 271
00:46:10 golf 271 golf 272
00:46:12 golf 272 alpha 241
00:46:14 alpha 241 sierra 1 3 police one hotel 421 and alpha 431 is that a first summary that's right and those pump appliances were in turn
00:46:25 and those pump appliances were in turn supplied with water from a total of four hydrants is that first of all let's deal with the basics is that right yes it is now if we can stay in this chapter but
00:46:36 now if we can stay in this chapter but go to page six
00:46:40 and if the map could be expanded that is a
00:46:45 that is a map of the area immediately surrounding grenfell tower and the tower itself is the bright green box labeled gt is that right correct
00:46:56 right correct the four larger circles highlighted in yellow
00:46:59 yellow show the four hydrants used to supply water on the night is that right correct and if we can take these in turn first of all h1
00:47:10 h1 is a fire hydrant located to the south east of the tower under grenfell walk is that right correct
00:47:17 correct h3
00:47:18 h3 is a fire hydrant located on the intersection of grenfell and beaumore roads is that right that's right
00:47:27 h8 is a fire hydrant located on bramley road is that right that's right and hydrant w0h5 seen here to the right of the tower
00:47:40 w0h5 seen here to the right of the tower is located next to the kensington leisure center is that right that's right it's between the classic and leisure center and the aldrich academy and just so people understand
00:47:52 and just so people understand the letters w o are important here and we'll discuss their importance later but w o stands for washout is that right that's right and finally this figure also shows with
00:48:04 and finally this figure also shows with the smaller red and blue circles other fire hydrants in red and wash out hydrants which are in blue situated in the vicinity of grenfell tower but which were not used on the
00:48:17 tower but which were not used on the night is that right that's right
00:48:22 now just going one apologize one extra thing here just wanted to emphasize is the private hydrant which is uh in close proximity to h1
00:48:33 proximity to h1 that private hydrant was labeled the most appropriate hydrant in the urd for the predetermined attendance specification thank you we'll come on to these matters
00:48:44 thank you we'll come on to these matters in due course can we first though before we come on to those other topics low flow rates and i'd like to turn in particular to your conclusions about that topic uh and
00:48:56 your conclusions about that topic uh and the flow rates delivered to aerial appliances and ground monitors on the 14th of june now if we can go to page in this chapter but go to page two three six
00:49:09 at point two you conclude as follows of the three aerial appliances and two ground monitors which projected water jets onto grenfell tower on the 14th of
00:49:21 jets onto grenfell tower on the 14th of june 2017
00:49:23 june 2017 none were supplied with their rated water flow rate and if we
00:49:29 and if we go on further between pages 236 and 238 you would go on to describe the specific details of each aerial appliance and ground monitor's rated flow figure compared with the flow rates which you
00:49:41 compared with the flow rates which you estimate that they received on the night we don't need to go through all of that detail which is set out on the next three pages but can i summarize that content and see whether you agree with
00:49:53 content and see whether you agree with the summary or not first of all alpha213 received about 60 percent of its rated flow is that right correct alpha 245 received between 16 and 20
00:50:08 alpha 245 received between 16 and 20 of its rated flow is that right that's right
00:50:12 right thirdly
00:50:13 thirdly sierra 1 3 alpha 1 received between 12 and 19 of its flow of its rated flow correct but for sierra 1301 we should
00:50:25 correct but for sierra 1301 we should also bear in mind that the actual monitor has a minimum flow rate and that minimum flow rate was not reached so although i can provide a value of
00:50:36 although i can provide a value of whatever percentage was delivered we should bear in mind that the actual flow rate was below the operational minimum threshold for that particular appliance the ground monitor on the south and east
00:50:48 the ground monitor on the south and east sides received between 63 and 86 of its rate of flow is that right correct
00:50:55 correct and the ground monitor deployed from the northwest corner received between 21 and 37
00:51:01 37 of its rated flow correct again another thing probably i might be jumping here a little bit is about the timeliness of this if
00:51:10 if if we can just deal with what i'm trying to do first of all is establish basics so there's a clear figure in people's mind and then if we can get into some of the detail later on
00:51:21 can get into some of the detail later on where it's necessary and relevant thank you now
00:51:24 you now what i'd like to deal with next is how you calculated the flow rate figures now
00:51:32 now first of all the mathematical model was provided by thames water which you then validated with practical testing carried out in 2018 and with data available from
00:51:43 out in 2018 and with data available from the night of the fire to ensure that it could accurately predict the flow and pressure conditions in the network at different times and locations during the fire
00:51:51 fire that in turn allowed you to estimate the flow rates delivered to the various pieces of firefighting equipment now that's high level but is that in its essence a correct summary of the
00:52:02 essence a correct summary of the approach you took it is and you just want to add to that that's clearly these mathematical models as we call them hydraulic models we have very high confidence into these models these are not just some abstract
00:52:14 these are not just some abstract highly uncertain we have common we commonly use them in a number of incident management and it's commonly used by the by the uk war industry as a whole modeling has its critics
00:52:27 modeling has its critics can you briefly emphasize the word briefly describe why you think the results are reliable or at least tolerably reliable because in terms of the actual model i
00:52:40 because in terms of the actual model i have taken a very robust approach towards the validation to use a lot of experimental work so i have very high confidence in the model in the hydraulic model and equally
00:52:52 model in the hydraulic model and equally through the testing of the flow coefficients of the hydrants i have now very good understanding about their discharge characteristics and in combination with understanding of the pressure and flow within the network and
00:53:04 pressure and flow within the network and the flow coefficients of the hydrants i can i can derive very re pretty accurate estimates of the flow rates coming out of this hydrogens now can i turn on to the next topic
00:53:16 now can i turn on to the next topic which is the consequences of low flow rates
00:53:20 rates now your report describes three consequences of low flow rates delivered to the aero appliances and the ground monitors and i just want to identify them at the start dr stonov and
00:53:31 identify them at the start dr stonov and then we'll come to deal the detail in due course first of all they limited the vertical reach of the jets projected onto the tower is that right correct
00:53:42 tower is that right correct secondly the low flow rates caused interruptions to the jets is that right correct so the jets were not consistent thirdly the low flow rates meant that some equipment could not be deployed as
00:53:54 some equipment could not be deployed as intended is that correct correct can i deal with the first one of those consequences which is limited vertical reach
00:54:05 now as you've confirmed the low flow rates limited the vertical reach of jets now before we go any further again dealing with basics vertical reach simply refers to the maximum height
00:54:18 simply refers to the maximum height reached by the projected water jet is that right correct your analysis identified that the three aerial appliances deployed at grenfell tower i use that phrase advisedly but
00:54:29 tower i use that phrase advisedly but for the sake of clarity which were able to reach higher than any other jets achieve maximum vertical reach of approximately 35 meters which is the 13th floor 47 meters the 17th
00:54:41 is the 13th floor 47 meters the 17th floor and 52 meters the 19th floor respectively is that right that was on the night of the fire yes as used
00:54:50 used now if we can go to page 238 and look at paragraph three
00:54:58 you conclude this alpha-213
00:55:02 alpha-213 turntable ladder offer 245
00:55:05 offer 245 aerial ladder platform and sierra 1 3 alpha 1 aerial ladder platform were capable of projecting water jets to the full height of the tower which was 65.4 meters if supplied
00:55:19 tower which was 65.4 meters if supplied with their rated flow and nozzle pressure from the pump appliances now if we turn back to page 52 in this chapter
00:55:32 we find at figure 5-2-9
00:55:37 5-2-9 an annotated graph and this graph is provided by the manufacturer of one of the aerial appliances i think alpha two on three and you've added
00:55:49 and you've added the writing in blue are those points correct
00:55:55 now we don't need to go through the graph in detail but i'd like to look in particular your blue markings and comments on the graph now you note that the graph shows that
00:56:07 now you note that the graph shows that when provided with the correct flow rate of 2000 liters per minute this appliance can project water to a maximum height of 35 meters from the nozzle
00:56:18 nozzle and adding that the maximum height of 30 meters at which the nozzle can be positioned using the appliance's cage that comes through a total of approximately 65 meters and that is the
00:56:31 approximately 65 meters and that is the basis for your conclusion that this particular aerial appliance alpha 213 had a maximum possible vertical reach of 65 meters which you note is to the top
00:56:42 65 meters which you note is to the top or thereabouts of grenfell tower is that a first summary of your conclusion annotated there correct
00:56:52 now grenfell ter is 65.4 meters high slightly more than 65 meters is it right put differently and in lay terms that the maximum vertical reach
00:57:04 terms that the maximum vertical reach of alpha 213 is there or thereabouts the total height of the tower correct
00:57:11 correct just to add to that clearly is that the manufacturer provides what they call the effective reach clearly and that effective reach is based on specific um again specific consideration about
00:57:23 again specific consideration about safety and etc that that's an orifice discharge so if if we can actually provide 10 and a half 11 bars even a very small deviation on that particular
00:57:37 appliance or that particular monitor that can even reach a little bit higher the other thing is that that water jet will be affected by environmental conditions we know that on the night of the fire the wind was very
00:57:48 the night of the fire the wind was very low we have the information from the weather stations so to as far as the environmental conditions go uh my my assumption is my hypothesis is that they had very little impact so in summary yes
00:58:02 had very little impact so in summary yes uh 65 meter is my estimate but um that's sort of a 40 centimeters you're referring to here it's it's certainly probably within the the maximum reach not the effective reach the effective
00:58:14 not the effective reach the effective reach is normally about 10 percent of the maximum reach and just picking up the variables that are in play here that achieving the maximum possible height depends not just on supplying the
00:58:26 height depends not just on supplying the appliance with the rated flow rate but also on the jet itself being projected at the optimal angle is that right
00:58:33 right that's correct yes and and equally um i'm sure we'll touch later but the actual experimental results which i'll be provided very much substantiate these results and just looking at this graph
00:58:45 results and just looking at this graph what we see is the tallest blue line rather i think this is what it shows is for a jet aimed at a 30 degree angle but if the jet is pitched at a shallower angle for example 40 degrees
00:58:57 angle for example 40 degrees the green line on this graph the maximum height reached by the jet falls at least the a so the lay eye quite significantly is that right correct okay can we just make sure we've
00:59:08 okay can we just make sure we've understood this correctly um
00:59:13 the angle of attack is the angle at which you are directing the jet is that right correct and
00:59:20 and it looks to me as though the blue line uh is an angle of attack at 75 degrees is that right well it depends how we measure the angle
00:59:31 well it depends how we measure the angle but yeah so so i think uh you're absolutely right the angle of attack here on the blue line will be 75 degrees so so you've got to point it as high as possible
00:59:42 as high as possible correct to get that extent of
00:59:46 extent of jet reach in a vertical plane that's right but uh when you look at uh just very basic trigonometry here in terms of angle distance where the actual area of appliance was positioned i don't think
00:59:58 appliance was positioned i don't think that was an obstacle to project that water jet at that particular angle well that
01:00:05 well that you may well be right i i just wanted to ensure that we'd understood the colors correctly but since i'm now broken into mr canoe's line of questioning i might ask one
01:00:17 line of questioning i might ask one further question um
01:00:19 um the horizontal reach shown on the graph yes
01:00:23 yes what is that telling us that so
01:00:26 that so clearly um that shows us what is the the furthest away reach which a jet can can outreach so if if let's say this this
01:00:37 outreach so if if let's say this this monitor is deployed in a situation where uh potentially the objective is to uh to outreach a fire on a on a industrial state or whatever you probably want to
01:00:48 state or whatever you probably want to be at a safe distance but have that outreach in terms of horizontal distance and consider that horizontal distance so that's the variations between the uh the
01:00:59 that's the variations between the uh the angle of projection and also the reach and the trajectory of that water jet and um is this graph telling us that in order to project a jet
01:01:12 to project a jet uh
01:01:12 uh 35 let's say meters above the nozzle yes you've got to be only 20 meters horizontally from the point at which you
01:01:23 horizontally from the point at which you want that to be achieved is it telling us that
01:01:27 us that not no no this this is no so it's uh so if if you want to project it as uh so that's what i'm saying it's a very basic trigonometry so if you take a triangle and i want to project that and i have
01:01:39 and i want to project that and i have the angle and i have the distance i can very much sort of the calculations in that particular case is probably about eight to nine meters distance uh in answer to your question i can achieve from the object where i want
01:01:51 can achieve from the object where i want to project it i'll be able to achieve that
01:01:54 that well
01:01:54 well let me ask my question in a slightly more um practical way how close to the building would you need to be in order to project a jet 35 meters
01:02:05 meters from the top of the ladder about 8 meters but equally if you bear in mind that the way 8213 was positioned it was positioned very close to the building but equally the
01:02:17 to the building but equally the projection was not done in that direction most of the time the projection was done along the building so in other words we didn't have that exact constraint uh the actual ladder could have been even
01:02:29 the actual ladder could have been even pulled a little bit more along the side and again the projection could reach to the top of the building without these constraints and equally eight two four five in terms of distance was the ideal distance to to achieve that projection
01:02:41 distance to to achieve that projection yeah that's helpful thank you very much yes mr clear just flowing from uh the chairman's question can we go to lfb double zero one two three six seven two
01:02:56 as we can see on the screen this is a report prepared by the lfb dated the 12th of november 2021 entitled flow tests conducted on aerial appliances types used at grenfell tower
01:03:08 appliances types used at grenfell tower fire if we go to page two of this document
01:03:13 we see in the third paragraph the report says this the flow tests summarized within this report were designed to assess the operational capability and performance of lfb equipment within the optimal
01:03:26 of lfb equipment within the optimal working parameters as provided within the dr stonoff report to ascertain whether the calculated provision of water could be achieved in an optimized working environment with equipment in
01:03:38 working environment with equipment in service at the time of the grenfell tower fire now in simple terms the report seeks to test whether your theoretical estimates uh for the maximum vertical reach of the
01:03:49 uh for the maximum vertical reach of the aerial appliances could be achieved in practice
01:03:53 practice was that your understanding of the overall point of the lfb's tests correct
01:03:58 correct now if we can go to the final paragraph of this introduction on page two which is immediately above the emboldened heading turntable ladder and monitor
01:04:10 heading turntable ladder and monitor it explains that the testing was carried out on the 25th of august and the 6th of september 2021 and looking at the middle of the second line of that paragraph and i quote
01:04:22 line of that paragraph and i quote all of the equipment assessed as part of the performance tests was produced by the same manufacturer and of the same model as that which attended the grenfell tower fire on the 14th of june 2017
01:04:34 2017 and we can see from the bottom of page 2 that the lfb tested a turntable ladder and if we go to page three
01:04:47 what's described there is an aerial lift platform
01:04:50 platform sometimes always described as an aerial ladder platform as well and an akron mercury quick attack monitor
01:04:58 monitor otherwise known as a ground monitor is that right correct the only thing i would like to add to this yes all of this equipment is described
01:05:08 described the the report does not explicitly specify the serial numbers of the monitors and the nozzles used into these tests and why is that important well generally we can even further
01:05:20 well generally we can even further validate with the manufacturer whether the specific serial numbers and have gone through the kind of testing which the manufacturer provides and that gives us additional reassurance it also
01:05:32 gives us additional reassurance it also it's important for us to really cross-reference that the tests which lfb have done which i think implicitly the statement is the assumption is that
01:05:43 the statement is the assumption is that these are exactly the same equipment of very similar equipment the similar branches is used on during the grandfather fire i would have liked to see the serial numbers of the equipment used on the grandfather fire and the
01:05:56 used on the grandfather fire and the serial numbers and exact models of the equipment of branches and nozzles used into these particular tests thank you now can we go to page 16 which sets out the results of the tests under the
01:06:08 the results of the tests under the heading conclusion roughly a third of the way down that page
01:06:13 page it sets out that the maximum jet height that was achieved for each piece of equipment tested which for the aerial appliances were 49 60 and 62.3 meters
01:06:24 appliances were 49 60 and 62.3 meters respectively the report then concludes in the paragraph below in the following terms for all of the flow tests undertaken within optimized practical working
01:06:35 within optimized practical working conditions the maximum throw of water achieved using equipment available at the time of the grenfell tower instant it was not possible to exceed 62.3 meters in
01:06:46 possible to exceed 62.3 meters in vertical water throw now
01:06:50 now put
01:06:52 put differently the lfb concludes that the lfb aerial appliances theoretical maximum vertical reach figures were not achievable in practice and that those aerial appliances were not capable of
01:07:04 aerial appliances were not capable of reaching the top of the tower now before we turn to your response was that your understanding of the lfb conclusions in this report that's very much my understanding of what will be
01:07:16 much my understanding of what will be concluded yes now you address the lfb's testing in page 21 of your supplementary report which we can find at is trps quadruple zero trouble zero one
01:07:31 trps quadruple zero trouble zero one forward slash 21
01:07:35 and we can see a paragraph 47 which is in the bottom third of that page you conclude thus
01:07:42 thus safe for performance test 3b which we don't need to go into for present purposes
01:07:47 purposes i do not agree that the lfb test results above are representative of the maximum achievable vertical reach of a projected water jet for the equipment tested in
01:07:59 water jet for the equipment tested in relation to performance tests one two and three a the lfb did not supply the tested monitors nozzles with their rated inlet pressure and or flow rate
01:08:11 pressure and or flow rate consequently the vertical reach of projected water jets observed by lfb in those performance tests is lower than the maximum achievable vertical reach of
01:08:22 the maximum achievable vertical reach of the tested monitors nozzles
01:08:25 nozzles now you say at the beginning of that paragraph say for performance 3b just so people know that was one of the lfb's tests of the grant monitor is that right
01:08:35 right that's right and just to note the ground monitor here has achieved 41.2 meters vertical reach which is actually exceeds my
01:08:44 my conservative estimates of about 35 meters
01:08:47 meters and you've excluded performance test 3b from your conclusion because that is the only test which you say did actually supply the correct pressure and flow rate
01:08:58 rate correct yes
01:09:01 now if we can put that ground monitor test to one side is it right that you do not accept the lfb's conclusions in relation to the aerial appliances because the appliances and i put this in
01:09:13 because the appliances and i put this in lay terms weren't supplied with the correct water pressure and flow rate that would have allowed them to achieve their maximum jet height that's correct and this to me was very
01:09:24 that's correct and this to me was very surprising given the fact that lfb had my recommendations in place now could we stay in this report but go to page 22.
01:09:38 we can see and we don't need to go through it in detail now but at pages from 22 through to 25 you set out your detailed analysis about why
01:09:51 out your detailed analysis about why the correct pressure flow wasn't provided
01:09:54 provided to the aerial appliances can you help the panel in brief what is your essential conclusion on that point why the correct pressure and
01:10:05 that point why the correct pressure and flow wasn't provided to the alps well as you said the most critical variables here is the nozzle inlet pressure and the flow rate for which this uh monitors and nozzles needs to be
01:10:17 this uh monitors and nozzles needs to be provided and this northwind pressure will depend on the pump discharge pressure and also the pressure head losses across the connections the the hoses the
01:10:29 the connections the the hoses the the different connections for these hoses so consequently if one does not have the right set of hoses which we would expect lfp to to take this into a
01:10:40 would expect lfp to to take this into a place and
01:10:43 place and there's no way they can provide the actual the nozzle inlet pressure required to perform this test which achieves that rated nozzle inlet pressure the other thing uh my view is that uh we do a lot of experimental
01:10:55 that uh we do a lot of experimental research and experimental research it's extremely critical to be able to go in a systematic way to validate your measurement equipment make sure that specific measurement is put in place and
01:11:06 specific measurement is put in place and and to my view lfb uh did not follow even basic standards in performing experimental tests for example uh one very simple approach would have been as i highlighted my response is to just
01:11:18 i highlighted my response is to just measure the nozzle inlet pressure at that particular point and that would have given us a lot of confidence in the repeatability and analysis of these tests and that was not done
01:11:29 tests and that was not done so to put it simply is it your view that uh to put this rather crudely i suppose lfb use the wrong nozzles uh no the uh that's not the case they
01:11:41 uh no the uh that's not the case they use the right nozzles because the nozzle is the actual part of the monitor but what they did is they didn't supply the nozzle inlet pressure which i specified in my recommendation which is part of this rated nozzle inlet pressure so in
01:11:53 this rated nozzle inlet pressure so in other words the pressure at the inlet to that nozzle was significantly lower and now i've kind of justified that they should have provided for for the purpose of these tests so they use the right nozzle but
01:12:05 tests so they use the right nozzle but without the maximum input pressure correct to that nozzle i see so to me i wasn't
01:12:12 wasn't i can't say whether this is it's it's really puzzling from my perspective whether that was lack of basic knowledge in pipe hydraulics or there were other factors in place and for that reason
01:12:23 and for that reason the contents of the lfb's testing does not cause you to doubt or qualify or amend the conclusions you reached not at all even if i look at the ground monitor if you go back to
01:12:35 if you go back to the lfb results and if you look at the specifically the ground monitor the ground monitor with the mercury uh mercury nozzle even though it doesn't get the nozzle inlet pressure has a much higher
01:12:46 inlet pressure has a much higher performance than the actual performance test 1a which is coming from the lfp and and broadly they are very similar nozzles and that sort of very clearly indicates to me
01:12:57 indicates to me again reaffirms my hypothesis that simply they didn't provide the correct nozzle pressure
01:13:06 just to give people a bite-sized summary okay you don't agree because the lfb testing failed to account for various pressure losses due to friction and gravity which occurred
01:13:17 to friction and gravity which occurred between the pump and the appliance where the lfb monitored the pressure and flow rate and the nozzle of the error appliance being tested correct and to me that has a big impact on any policies lfp can drive from these
01:13:30 on any policies lfp can drive from these tests secondly the lfb didn't use state-of-the-art equipment to monitor pressure or flow and instead relied on physically looking at mechanical gauges and manual recording correct thirdly the
01:13:43 and manual recording correct thirdly the testing was carried out using a single fire hydrant as a water source with a flow rate of 2 000 liters per minute which was less than the required flow rate of 2
01:13:54 rate of 2 400 liters per minute is that right correct
01:14:00 don't want to take this too crudely or simplistically but those are three principal reasons uh why you are not persuaded by the results the lfe gathered as a result of that testing that's right
01:14:12 that's right can we look at matters slightly differently from a different perspective now and look at the uh
01:14:18 uh the issues that arise out of your own estimates of the jets vertical reach i'd like really to discuss and identify the limitations of your own estimates now first of all your estimates are just
01:14:30 now first of all your estimates are just that they're estimates um based on desktop calculations uh which have not been replicated in the practical real-life situations is that a fair point to make it is a fair point
01:14:43 point to make it is a fair point secondly there could be other factors which are not included in your calculations and which may lie outside your expertise but which may affect an aerial appliances achievable vertical reach again is that
01:14:55 achievable vertical reach again is that a fair generic observation i i i would like to know what uh how we describe this other factor so we should be able to agree well let's go through them because there are some of the ones
01:15:06 them because there are some of the ones you identified earlier in your evidence first of all weather conditions correct but again as as stated uh uh we cross i cross reference the weather
01:15:17 cross i cross reference the weather conditions from the meteorological office stations and equally that was done by other experts such as professor luke bisby on uh and the impact on the weather conditions in
01:15:28 the impact on the weather conditions in wind on let's say the fire spread and their conclusions is that with minimum and equally the same conclusion i can draw for the the projection of the water dr stonov could i ask you to take
01:15:40 dr stonov could i ask you to take matters
01:15:41 matters more slowly okay stenographers finding it difficult just to keep up thank you another factor which may need to be put into the balance here is the performance of the appliance itself which may have declined
01:15:54 appliance itself which may have declined to some extent since factory conditions due to continuing use is that a legitimate point to bear in mind as well
01:16:05 um
01:16:08 so one so we have several factors here clearly we have the pump discharge pressure and i specifically asked for all maintenance records for the centrifugal pumps to be
01:16:20 records for the centrifugal pumps to be made available to me and these maintenance records indicate that the performance of these pumps were well within the expected specifications of these pumps so any other equipment that
01:16:31 these pumps so any other equipment that might deteriorate somehow is the actual nozzle geometry or some of the components of the nozzle but but again i would find that difficult to believe so so my
01:16:42 so my my assumption is that actually this this equipment should have performed to its operational specification but perhaps as your answer indicates performance of the appliance and the
01:16:54 performance of the appliance and the various
01:16:55 various uh
01:16:56 uh supplemental bits of equipment are is a legitimate factor to bear in mind when considering maximum vertical reach it is there may also be
01:17:07 there may also be operational fire fighting reasons which factor into decisions about the use placement or projection angle of an aerial appliance at a firefighting instance
01:17:16 instance give a practical example burning debris falling off a building and having to avoid that uh correct that's uh i thought i fully agree but equally we see the example of
01:17:29 agree but equally we see the example of alpha 245
01:17:31 alpha 245 which clearly was at a distance to the building we don't necessarily have to go to it but
01:17:39 but the lfb report noted that water at the highest peak of the maximum jet height fell very sharply downwards and created a significantly wider more dispersed cone of water with reduced energy
01:17:52 cone of water with reduced energy that in the report author's professional judgment as a firefighter would have significantly reduced effect on firefighting operations uh due to the dispersed nature of water at that height
01:18:04 dispersed nature of water at that height that is a legitimate consideration to bear in mind would you accept that proposition yes i would however again it's uh it's probably
01:18:15 however again it's uh it's probably that will go beyond the scope of my uh of my investigation but it seems that we do have evidence to suggest that even small amounts of water can very
01:18:27 small amounts of water can very effectively deal with the heat flux on these specific acm panels so that is the end of my questions on the first consequence of low flow rate which is probably a reasonable place to
01:18:39 which is probably a reasonable place to stop if i think it is yes well dr stone enough we have a break during the morning in any event and this is a good time to take it so we'll stop there we'll resume please at 25 to 12
01:18:50 at 25 to 12 and i have to ask you while you're out of the room not to discuss your evidence or anything relating to it with anyone else thank you thank you very much would you go with the usher please thank you
01:19:08 thank you very much 25 to 12.
01:35:40 would you ask just oil enough to come back in please thank you
01:35:55 all right ready to carry on hi thank you good thank you very much yes mr canada just uh mr kenya before we continue may i just revisit your question uh before the break uh with regards to the uncertainties
01:36:07 uh with regards to the uncertainties associated yes i would just again on the reflection i mean absolutely i think all these uncertainties you've identified the rightfully they should be raised but
01:36:18 rightfully they should be raised but this is again the reason why this experimental validation is supposed to address these uncertainties and bring better clarification uh and and the examples with let's say temps water we run this
01:36:31 with let's say temps water we run this experiment jointly we we had an agreed protocol of how to run the experiments on collecting hydraulic data from the network
01:36:39 network on the basis of which we can have the discussion with unfortunately with lfb we did not have that interactions in terms of running the test and agreeing on processes procedures and measurements so in the
01:36:51 procedures and measurements so in the end of the day it's very difficult for me to use these validation results to to really address some of the uncertainties you mentioned plea please don't worry dr stone off you've made your your point
01:37:02 stone off you've made your your point very clear and you've re-emphasized it now thank you so can i now turn to the second consequence of the low flow rate you identified in your report and that was in broad terms interruption to jets
01:37:14 was in broad terms interruption to jets and if we can go to istrp quadruple zero trouble zero six forward slash two three six
01:37:27 now this sets out some of your conclusions from chapter five of your report and if we could look at the end of line 10 in paragraph 2 you say this the insufficient flow rates into the
01:37:39 the insufficient flow rates into the on-board tanks or pump appliances also resulted in frequently stopping the operation of the on-board centrifugal pumps to allow the tanks of the supplying pump appliances to be refilled
01:37:52 supplying pump appliances to be refilled managing the water deficit between the inlet flow rate into an onboard water tank of a pump appliance and the outlet flow for a projected water jet resulted
01:38:03 flow for a projected water jet resulted in continuous variations in the jet's flow and reach now earlier we discussed the concept of continuity of flow and that is what was essentially lacking
01:38:14 and that is what was essentially lacking here in broad terms is that the point in a nutshell yes less water was going into some pump appliance tanks than was being pumped out of them to firefighting equipment so
01:38:26 out of them to firefighting equipment so the tanks would repeatedly empty the jets had to be stopped to allow refilling and then to start up again and that's the essence of the problem correct and i i believe we we have very good
01:38:39 i i believe we we have very good cross-reference of this by firefighters on the night in their witness statements now in some cases jets could be deployed for less than a minute before the pump tank ran out requiring the jet to be
01:38:51 tank ran out requiring the jet to be paused for 20 seconds or so before the tank refilled and the jet could be restarted is that right correct
01:39:00 one partial solution which firefighters were able to improvise
01:39:05 improvise to prevent these interruptions was to turn down the pump settings so that less water was pumped out to the firefighting equipment to match the limited flow of water coming into the tank
01:39:17 water coming into the tank it's right that that's what was attempted on the night wasn't it that's right and we can look very closely at the pump characteristics to see that behavior in the moment you start reducing the flow rate you're reducing
01:39:29 reducing the flow rate you're reducing the pump discharge pressure and that has an impact on the nozzle inlet pressure that's the that's the big downside to that particular approach isn't it because
01:39:39 because in order to ensure continuous or near continuous supply of water you'd have a much weaker diminished jet of water correct
01:39:47 correct and this is very much these are variable speed pumps the pump appliances have very powerful variable speed pumps and that's the relationship between pressure pump discharge pressure and flow rate is
01:39:59 pump discharge pressure and flow rate is very well represented there can we now turn to the third consequence of low flow rate that you identified which was in essence that some equipment could not be deployed
01:40:10 could not be deployed now
01:40:12 now as you identified in earlier evidence and i said we'd come on to
01:40:17 the there were problems with alpha 245 and aerial appliance in that the water flow rate it received was insufficient effectively to project a jet of water from its higher capacity nozzle in a
01:40:30 from its higher capacity nozzle in a nutshell is that right correct and again to use a horticultural analogy it's a bit like a large garden hose receiving only a small stream of water
01:40:42 receiving only a small stream of water such that the water just dribbles out and isn't projected any distance from the hose i agree although i would like to use a more scientific explanation yes in essence that's the problem that's
01:40:53 in essence that's the problem that's right
01:40:55 right firefighters again had to improvise which they did by strapping a lower capacity fire hose to the cage of aerial appliance to produce a jet which could reach the tower is
01:41:06 a jet which could reach the tower is that a first summary of what was attempted on the night that's right again apologies for using the garden hose
01:41:13 hose analogy
01:41:14 analogy but that's equivalent to pinching the opening of the hose with your thumb to produce the longer but necessarily narrower stream of water correct
01:41:24 having identified those consequences can we now turn to the
01:41:29 the topic of the causes and
01:41:33 and for that purpose can we stay in chapter 5 but go to page 238
01:41:39 and in particular could we look at paragraph 6
01:41:44 and here you provide a neat summary of the causes for us and you said this the reasons for the low flow rate extracted from the hydrants at grenfell tower include a
01:41:55 tower include a the low flow discharge coefficient of the used hydrants b
01:42:01 b in the case of alpha 245 alp and sierra 1 3 alpha 1 alp the use of a washout hydrant h5 which was wrongly labeled fire hydrant a
01:42:14 which was wrongly labeled fire hydrant a washout hydrant is not designed for the supply of water for fire fighting c
01:42:20 c lack of coordination between lfb and twul this also included the continued pressure reduction in the water distribution system by twul
01:42:32 twul d
01:42:33 d pressure losses between the hydrants and the pump appliances now what i'd like to do dr storinov is go through each of those causes with you and first of all can we deal with the
01:42:44 and first of all can we deal with the hydrants low flow coefficients which will necessarily bring in a question of interpretation of the relevant british standard now if we can go to istrp
01:42:57 now if we can go to istrp quadruple zero treble zero eight forward slash seven two
01:43:08 now at lines 19 to 20 on page 72 you explain that the low sorry that the flow coefficient of a hydrant is a measure of
01:43:20 coefficient of a hydrant is a measure of the flow rate of the hydrogen can provide in relation to the pressure at that point in the distribution network close quotes now in layman's terms is the flow coefficient essentially a
01:43:32 is the flow coefficient essentially a measure of how efficient the hydrant is in that it measures how good a flow rate the hydrant can supply given the pressure of the water the hydrant receives from the network
01:43:44 hydrant receives from the network good act
01:43:46 good act so the higher the flow coefficient of a hydrant the better absolutely i mean if you scroll up that page um we can it's no more than gcse maths here but if
01:43:59 it's no more than gcse maths here but if you scroll up that page you would very much see the uh the flow discharge equation from an orifice and clearly if that coefficient is higher
01:44:10 is higher so this is equation 6.2 for example um this is the actual calculation of the flow coefficient but equally don't know if i don't think we need to go in okay
01:44:21 if i don't think we need to go in okay possibly to save my blushes about gcse maths but just for the conveying the essential of the consequence we need here that's fine i think we agree i shall follow your advice
01:44:32 advice um your report sometimes refers to the flow discharge coefficient of hydrants um is that because the terms flow coefficient and discharge coefficient
01:44:43 coefficient and discharge coefficient are both used and are interchangeable at least in this context that's right now your report distinguishes between the flow coefficient of a standalone hydrant and i'd like to emphasize that
01:44:55 hydrant and i'd like to emphasize that word stand alone and the composite flow efficient of a hydrant
01:45:02 hydrant in lay terms can you explain for us the difference between the two so the difference between the two is that um
01:45:10 that um one is
01:45:11 one is the
01:45:12 the if one looks at the flow coefficient of discharge of a hydrant uh one could imagine that this just correlates to the hydrant in isolation so in other words i can take a
01:45:24 isolation so in other words i can take a hydrogen put it on a pipe brick at imperial and i can test this hydrant and look at specific flow coefficient or discharge characteristics of that fire hydrant now if i take this fire hydrant
01:45:37 hydrant now if i take this fire hydrant and install it in an operational network the connecting pipeline or the connecting piping around that hydrant might significantly differ than these kind of ideal piping arrangements under
01:45:50 kind of ideal piping arrangements under which i've tested that particular fire hydrant and that becomes very important in in urban environment where you know when you dig a street to install a fire hydrant there is a whole sets of different infrastructure and in order to
01:46:02 different infrastructure and in order to avoid that infrastructure and i've shown pictures of actually excavation of hydrants in london you might have a number of elbows different connecting pipe and etc so suddenly that hydrant which performed
01:46:15 suddenly that hydrant which performed extremely well in my lab when i actually put it in real operational conditions because of the connecting pipe work might have very different performance characteristic as a whole and ultimately
01:46:27 characteristic as a whole and ultimately that impacts the outcome of how much flow i can discharge so so that's why i sort of make that difference between uh the kind of almost standalone hydrant versus that sort of a composite flow
01:46:39 versus that sort of a composite flow coefficient so composite flow coefficient is the flow coefficient of an installed hydrant including the pipes and bends which connect that hydrant to the rest of the network correct
01:46:51 the rest of the network correct whereas a standalone coefficient is just that the clues in the title the flow coefficient of only the hydrant tested in factory settings without the
01:47:02 tested in factory settings without the connecting pipe work so
01:47:04 so in general yes but again as we saw in my response even the testing of these hydrants under any forms of standard includes a small section of conducting
01:47:15 includes a small section of conducting pipe work and they are explicitly taken into account so we're not just testing the
01:47:20 the the hydrant as a hydrant that tests even according to british standards they include certain connecting pipe work and that's very explicitly described can we say that a hydrants composite
01:47:32 can we say that a hydrants composite coefficient is likely to be lower than its standalone coefficient due to inevitable pressure losses introduced by pipes and bends connecting the hydrant to the rest
01:47:43 bends connecting the hydrant to the rest of the network correct it will be equal or less
01:47:47 or less now you touched in your answer and i touched in the introduction to british standard 750 2012 which is entitled specification for
01:47:58 2012 which is entitled specification for underground fire hydrants and surface box frames and covers we find that standard bsi quadruple 0-1767
01:48:14 can we go to paragraph 10.2 which is on page 13 1 3.
01:48:23 and we'll see here under the subheading hydraulic characteristics paragraph 10.2 stipulates that and i quote when fitted with a standard round thread outlet
01:48:36 with a standard round thread outlet the fire hydrant shall have a kv value of not less than 92 now the reference to kv value here is shorthand for cl for flow
01:48:47 here is shorthand for cl for flow coefficient is that right correct now
01:48:52 now you say in chapter four of your report and might be useful to go to it istp quadruple zero five forward slash nineteen
01:49:11 thank you if we could look at line nine
01:49:16 bearing in mind that kv value you said this
01:49:19 this it is not entirely clear whether the 92 units flow coefficient requirement in bs 750 2012
01:49:28 750 2012 refers to the hydrant as a standalone valve or when installed in a water distribution network in other words it is not entirely clear whether the 92 requirement relates to
01:49:40 whether the 92 requirement relates to the standalone flow coefficient or the composite flow coefficient of a hydrant is that
01:49:48 is that the essential query you're raising here correct
01:49:51 correct and you go on to say that your view is that it refers to the composite flow coefficient is that right that's right now
01:50:00 now if we can just look at the british standard because it's a topic which you considered in your supplemental report can we go to that report i s t r p s
01:50:12 can we go to that report i s t r p s quadruple zero treble zero one forward slash six
01:50:20 and if we look at paragraph seventeen you set out here your belief that the 92 requirement in the standard refers to the installed
01:50:31 the standard refers to the installed hydrant with connecting pipe work in other words to the composite flow coefficient for four reasons and you go through these reasons at length over the
01:50:42 these reasons at length over the uh the next 15 pages we i don't want to go through those points in detail but could i summarize them and see whether you agree that i've summarized them correctly
01:50:54 summarized them correctly the four reasons you rely upon for your interpretation the standard are these first
01:50:59 first it follows an integral principle in systems engineering i.e
01:51:05 i.e that in engineering you're less concerned with individual performance of an isolated part of a system and you are more concerned with the performance of the system as a whole is
01:51:16 performance of the system as a whole is that a first summary of that reason yes it is
01:51:19 it is secondly you refer to bs en 60534-2-1
01:51:26 which is a related standard which describes the process of testing and certifying the flow coefficient that's the kv value of a valve a hydrogen's a valve
01:51:37 a hydrogen's a valve includes the connected pipe work is that the second reason you rely upon for your interpretation correct thirdly you note that evidence from relevant stakeholders suggests a common
01:51:48 relevant stakeholders suggests a common understanding that the kv requirement of 92 refers to uninstalled hydrant and connecting pipe work again is that a fair summary of the third reason you rely upon
01:51:59 rely upon that's right because a lot of these stakeholders they refer to a particular pressure and particular flow rate for a hydrant on the basis of which we can then refer back to that value of 92
01:52:11 then refer back to that value of 92 and finally you refer to the absence of a meaningful standard if an alternative view is taken again have i summarized at least the essence of that correctly
01:52:24 essence of that correctly that's
01:52:25 that's true because if we don't have that understanding of the composite values and that needs to be interpreted by a professionally uh someone a professional who understands these pitfalls and ambiguity of the standards
01:52:38 pitfalls and ambiguity of the standards then we have no alternative i can i can connect that hydrant with a garden hose using your example and i would still pass all the british standards now can i examine your reasoning in more
01:52:49 now can i examine your reasoning in more detail of that latter that fourth point and it's something you set out in detail at page 15 of your supplemental report and if we could go to that
01:53:04 in essence what you say is that if the 92 requirement refers to a standalone hydrant in factory conditions there would be no standard or requirement governing the performance of an
01:53:15 governing the performance of an installed hydrant and hydrants could therefore be installed very poorly without breaching any relevant standards i put that crudely but is that the essence of what you're saying yes
01:53:27 you're saying yes now your supplemental report acknowledges factors which may be read as pointing in the opposite direction and for an alternative interpretation of the standard and to
01:53:38 interpretation of the standard and to this end can we go to turn over the page to page 16 and look at paragraphs 38 and 39
01:53:45 39 dr stone off it's probably easier if i read these out paragraph 38 reads thus i have described above my reasons for adopting what in my judgment appears to be the most appropriate interpretation
01:53:57 be the most appropriate interpretation of the requirement that it relates to an installed hydrant with connecting pipework in a water distribution network i've also explained that the alternative standalone manufacturing only
01:54:08 standalone manufacturing only interpretation would lead to a surprising absence of legal requirements relating to the installation and real-world efficiency of hydrants paragraph 39
01:54:20 paragraph 39 however
01:54:21 however given the ambiguity in the wording of bs 750 i cannot go so far as to say that the standalone interpretation is a wholly unreasonable interpretation of
01:54:32 wholly unreasonable interpretation of bs750
01:54:34 bs750 elements of the wording of bs 750 may be taken to lend some support to that interpretation the scope section of bs 750 states that this british standard applies to
01:54:45 this british standard applies to underground fire hydrants to be installed in a water supply system following the description of the k value requirement of 92
01:54:56 requirement of 92 bs750 adds the k value kv value of the fire hydrant shall be specified in the manufacturer's literature and there are a number of other references to the manufacturer
01:55:08 references to the manufacturer these references may be taken to mean that the standard applies to standalone hydrants in manufacturing or factory conditions now bearing in mind what you say there
01:55:19 now bearing in mind what you say there would you also agree that the absence of a minimum standard relating to a hydrants flow coefficient which would exist if the standalone interpretation of bs750 is adopted
01:55:30 interpretation of bs750 is adopted well perhaps unsatisfactory does not mean that we should read british standard 750 in such a way to bridge that gap um i i agree it's um
01:55:42 um i i agree it's um yeah i if i if i look at it scrutinized from very as you said legal perspective yeah the description is very ambiguous if i look at it from from the perspective of a hydraulic engineer i
01:55:55 perspective of a hydraulic engineer i would have sufficient knowledge to recognize that ambiguity and take it into account looking at what you say in paragraph 39 and where you say that the standalone
01:56:07 and where you say that the standalone interpretation
01:56:11 is not a wholly unreasonable interpretation of that standard could we look at it slightly differently ignore the double negative and accept that the standalone interpretation
01:56:22 that the standalone interpretation is a reasonable one albeit one with which you don't agree
01:56:31 well as i said if i'm not technically competent i would find this is a reasonable explanation
01:56:41 thank you can we now look at a separate topic which is the flow coefficients of the hydrants at grenfell town and as a part of your investigation into
01:56:52 and as a part of your investigation into the water supply to the tower you carried out testing in july and september 2018 which enabled you to calculate the composite flow coefficients of some of the hydrants at the tower including those that were used
01:57:04 the tower including those that were used to supply firefighting efforts on the night is that correct correct we can see the detailed results of those calculations at i s t r p
01:57:17 at i s t r p quadruple zero treble zero eight forward slash one double zero
01:57:26 and if that table could be slightly expanded
01:57:32 hydrogen h1 had a flow coefficient of 74 is that right correct h3 had a flow coefficient of 50 is that right correct
01:57:44 right correct wash out hydrant h5 had a flow coefficient of 31 is that right correct and hydrant h8 had a flow coefficient of 50. is that correct correct
01:57:56 50. is that correct correct now if your preferred interpretation of bs 750 is adopted those hydrants should have a composite flow coefficient of no less than 92
01:58:08 flow coefficient of no less than 92 so that each of the four on these figures fell well short of that standard would that be right that's right
01:58:15 right however
01:58:16 however if the alternative interpretation is adopted but the 92 requirement refers only to the standalone hydrant is it right to say that you wouldn't be able to conclude from your testing that
01:58:28 able to conclude from your testing that the hydrants fell short of that standard because you were only able to test their composite flow coefficient that's right but the ultimate goal here is to deliver water for firefighting so
01:58:40 is to deliver water for firefighting so i
01:58:41 i you know having a coefficient of a hydrant which delivers no water is of no use to anyone can we go back to your supplemental report i s t r p s
01:58:53 report i s t r p s quadruple zero treble zero one forward slash sixteen
01:59:01 and we can see it paragraph 40 which is the very foot of that page you say this and it just flows from the point you've made
01:59:09 made even if the alternative view were adopted
01:59:12 adopted that the kv flow coefficient standard of 92 and bs750
01:59:18 bs750 relates to a standalone hydrant one would expect the installation of hydrants to be carried out in such a way that the kv the flow
01:59:29 in such a way that the kv the flow coefficient of the hydrant installed in the water distribution network remains as close as possible to or exceeds 92 by minimizing any possible performance
01:59:40 by minimizing any possible performance loss from the installation setup and connected
01:59:44 connected pipe work
01:59:46 pipe work now mindful of what you've said there regardless of which interpretation of the british standard is preferred would you have expected the flow coefficients of the hydrants installed
01:59:58 coefficients of the hydrants installed at grenfell to be higher than they turned out to be on the basis of the figures you've identified this is correct because again that has an implication on the flow rate which
02:00:09 an implication on the flow rate which can be delivered to the london fire brigade to perform their duties i think what
02:00:14 what we would find it helpful to know and i think this is the thrust of mr clear's question is if we look at the figures we've got in the table we had up a little earlier are they
02:00:25 are they in your experience typical uh
02:00:29 uh well
02:00:30 well it's um so let me step take a step back the only way we can identify whether it's a typical or not by doing float test of hydrants and float tests of hydrons are not carried out by the water
02:00:42 hydrons are not carried out by the water utilities or by the london fire brigade i would like to refer to our paper which was published a year before um
02:00:51 um grandfather fire which was by a firefighter in in southwest london he did carry out something along the lines of 600 tests of fire flow test fire hydrants in southwest london and his
02:01:04 hydrants in southwest london and his conclusion was that about 20 percent of these tests almost were inoperable and a very large percentage almost like over 30 percent i believe based on memory had flow rates less than 500 liters per
02:01:17 flow rates less than 500 liters per minute so in answer to your question it seems to be uh you know my sample is not representative out of these five hydrants to draw exact conclusion
02:01:28 hydrants to draw exact conclusion although all these results show a much lower values but if i extrapolate this to the kind of publications of an active firefighter who has gone and done that test it seems that this is a
02:01:40 done that test it seems that this is a very representative sample of what what's happening in london that most of these fire hydrants do not have this discharge characteristics which we expect them to have and
02:01:51 have and is it possible to say whether the discrepancies between the standalone coefficients and the composite coefficients are likely to be due to
02:02:05 coefficients are likely to be due to the the
02:02:06 the the state of the pipe work it's the installation conditions of this and and because we do not you know there's no obligation to flow test these fire hydrants once these are commissioned we have no information and
02:02:19 commissioned we have no information and the regular testing of these fire hydrants of london fire brigade does not include flow testing of these fire hydrants
02:02:25 hydrants it's a lottery we don't know what that discharge correct fissions and characteristics would be until lfb have to deliver the required flow rates
02:02:37 to deliver the required flow rates one of the things that seems to me to come out of this possibly relates to the construction of the british standard that you were referring to a moment ago
02:02:48 that you were referring to a moment ago because
02:02:51 unless there are factors at work which we're not aware of if you look at these figures
02:02:56 figures it suggests that there can be a difference of almost 50 between the rated
02:03:02 rated flow rate so to speak correct and the actual flow rate correct now um i don't know how you can accommodate that within a standard setting
02:03:14 within a standard setting document
02:03:15 document because if the operational conditions can have that degree of influence over performance
02:03:27 performance then um
02:03:29 then um how are you going to know whether you've got
02:03:31 got uh hydrants which will which have a coefficient of 92 you won't win that was the right point you wouldn't unless you test them you wouldn't know you could but you've got to test
02:03:42 to test all of them in operation because they've got to have the connected pipe work correct and that's one of my points i made in chapter four that a lot of countries around the world
02:03:53 that a lot of countries around the world fire rescue services have this periodic flow test full flow test of hydrants because it's not just about the installation conditions but over a period of time these things can deteriorate and that's why this periodic
02:04:06 deteriorate and that's why this periodic flow test of hydrants becomes extremely important and as i pointed out in my results if i know the flow discharge characteristics of fire hydrants for example i point out that in france they do them every five years or three years
02:04:18 do them every five years or three years depend on certain conditions and i know the hydraulic conditions of this system i can be very definite in the kind of flow rates the water utility can provide to uh to
02:04:30 the water utility can provide to uh to the fire rescue service but this might in turn have a an implication for how one reads the british standard cute yes because well it may be very
02:04:42 cute yes because well it may be very it may be more doubtful that the pretty standard institution is setting out to prescribe minimum requirements which themselves are dependent on operating conditions do you see what i mean
02:04:55 conditions do you see what i mean this is where i in my response i try to track back the kind of where these values are coming from and and if you start seeing these kind of variations of british standards i think the overall
02:05:06 british standards i think the overall meaning was lost so clearly we need to define that that component has certain specifications but that we also need to recognize that that component as part of the whole system needs to preserve these
02:05:18 the whole system needs to preserve these specifications because ultimately a firefighter expects let's say 2000 liters per minute to come out of fire hydrant in london and that's the ultimate goal we need to deliver
02:05:29 ultimate goal we need to deliver but of course if i mean the british standard refers to the flow rate being stated by the manufacturer now the manufacturer cannot possibly
02:05:40 now the manufacturer cannot possibly state a flow rate which is dependent on operational circumstances can he
02:05:46 can he no he can't but uh that's why i was kind of going back to the notion of performance of components yeah so that's uh a very much component performance but then the person who put that component
02:05:58 then the person who put that component into the system needs to be qualified and technically knowledgeable to recognize the pitfalls what might happen with that particular component and that's why ultimately we
02:06:11 component and that's why ultimately we also need to have this flow test so once that hydrant is installed and commissioned we didn't need to understand what actually happened out there because there's all sorts of other human factors
02:06:22 there's all sorts of other human factors i mean a lot of these installations are done by subcontractors probably with very low level of supervision and i've seen
02:06:29 seen many examples of horrendous installations in that respect well that's helpful thank you very much i'm sorry i've been responsible for a bit of a digression there but no thank you no it's useful thank you
02:06:40 it's useful thank you um can i now turn to another reason for the low flow rate which was the use of a washout hydrant it's a topic we've touched upon earlier but i'd like now to turn to it in more detail and to this
02:06:52 turn to it in more detail and to this end can we go to istrp
02:06:56 istrp quadruple zero trouble zero six forward slash two three eight and paragraph six
02:07:05 this is what we looked at slightly earlier but just to sort of reorientate yourself in your report the second reason you identified for low flow rates was and i quote in the case of alpha 245 alp and sierra one three
02:07:19 of alpha 245 alp and sierra one three alpha one alp the use of a washout hydrant h5 which was wrongly labeled fire hydrant a washout hydrant is not designed for the supply of water
02:07:30 supply of water for fire fighting if we can stay in this or rather go to chapter six of your report which we find at a i s t r p quadruple zero trouble zero eight
02:07:43 quadruple zero trouble zero eight forward slash seven nine
02:07:48 uh we find at the beginning of line ten some more detailed explanation of a washout hydrant and its differences from a fire hydrant and you say this
02:08:01 from a fire hydrant and you say this h5 is a washout hydrant which is a which is different from a fire hydrant as explained in chapter 4 washout hydrants are used for operational and maintenance purposes
02:08:13 maintenance purposes and enable water companies to flush sediments and stagnant water from specific locations the flushing is generally done at flow rates significantly lower than the flow
02:08:24 rates significantly lower than the flow rates expected from fire hydrants for fire fighting washout hydrants are not aimed and installed supply water for fire fighting washout hydrants look identical to fire hydrants and should be clearly marked eg
02:08:37 hydrants and should be clearly marked eg with a w
02:08:39 with a w to distinguish them now although they have a different purpose to fire hydrants a washout hydrant may be structurally the same as a fire hydrant and connected to the water network in exactly the same way as
02:08:52 water network in exactly the same way as a fire hydrant is that right correct
02:08:56 correct if we go
02:08:57 if we go to the table at page 100 of chapter 6 which we find at istrp quadruple zero trouble zero eight forward slash one hundred
02:09:25 thank you we see if we look for h5 which is at column five and we can see that it has the lowest composite flow efficient of all the
02:09:36 composite flow efficient of all the hydrants you tested that's presumably something you'd have expected due to its different function and design could actually i've demonstrated a photograph which shows the installation
02:09:48 photograph which shows the installation of hydrants and washer hydrants and we can visually observe the different pipework associations
02:09:57 so um are you looking for the photograph uh yes sorry i don't have the document in front of me so i my memories i don't have the reference to turn expectantly
02:10:08 have the reference to turn expectantly to someone behind me i don't have that reference immediately to mind but okay if we can just maybe just move on with some text before we find that photograph if we can go back to page 79 of chapter six which is
02:10:21 back to page 79 of chapter six which is istrp quadruple zero trouble zero eight forward seven nine
02:10:30 and if we can see in the next paragraph from line 16 onwards you say this washout h5 is owned by thames water and it was installed in february 2014.
02:10:43 it was installed in february 2014. as i detailed in chapter 5 washout hydrant h5 was mistakenly labeled fh fire hydrant on the metal lid of the hydrant chamber
02:10:54 hydrant chamber firefighters would not have known that they were connecting a pump appliance to a washout hydrant on the 14th of june 2017.
02:11:01 2017. however the digital maps of the twul's network service technicians had the information that wash out hydrant h5 is a washout hydrant
02:11:13 hydrant h5 is a washout hydrant now having been mislabeled fh and as washout hydrants and fire hydrants otherwise look identical was there any way for firefighters to identify that h5 was a washout not a
02:11:25 identify that h5 was a washout not a fire hydrant not really um it's i mean there was a number of factors which were identified through the witness statements first of all the
02:11:36 witness statements first of all the mobile data terminal of the pump appliance in close proximity was not working
02:11:42 working secondly uh we have witness statements which demonstrated they tried to attach a
02:11:49 attach a standpipe to one of the nearby fire hydrants which i've also identified was inoperable and then probably in the night my my assumption is that they just stumbled across this additional hydrant
02:12:00 stumbled across this additional hydrant which was labeled fire hydrant so in the urge of the situation it would be extremely difficult i would imagine is to
02:12:08 to extensively test that this was actually not a fire hydrant but a washout hydrant which wasn't practical it was not practical that's right going back to your earlier request if we can stay in this chapter and go forward
02:12:20 can stay in this chapter and go forward to page 81
02:12:28 this is a series of photographs of h5 the washout hydrant was this what you had in mind uh correct i mean that during my experimental tests i noticed
02:12:40 during my experimental tests i noticed that
02:12:41 that the we sort of went through all the kind of hydrants in the area and i noticed that clearly from the evidence that this was the hydrant used by uh london fire brigade on the 14th of june
02:12:53 brigade on the 14th of june and i noticed that that was labeled fire hydrant while my records in the in the gis provided by temps water that was labeled as a washout hydrant and the other impact of that is that clearly lfb
02:13:04 other impact of that is that clearly lfb would not have been doing any tests on that fire hydrant even the very basic mechanical test they were doing that sort of brings me to the other hypothesis that is we know that
02:13:16 hypothesis that is we know that london fire brigade had problems opening that fire hydrant that hydrant fully and the network service technicians opened that hydrant fully at about 5 30 and even then the flow rate was very low so
02:13:29 even then the flow rate was very low so my interpretation of that is because of these miscaps of labeling that hydrant it was not just the issue of the the flow rate but also was the issue that there were certain mechanical potential
02:13:40 there were certain mechanical potential issues with the stamp of that particular hydrant thank you now
02:13:47 and so just to kind of apologize just to add up so i i i kind of notify because times water was on site they were overseeing my work and
02:13:58 on site they were overseeing my work and overshot and shadowing my work i've notified them that this should be a washout hydrant and it seems shortly afterwards that was replaced with a w plate thank you
02:14:10 a w plate thank you we're going to come on later um to the involvement of thames water but could i turn to um a further reason for low flow rate and that was pressure losses between the hydrants and the
02:14:23 losses between the hydrants and the pump appliances if i can just start off with something basic so we know what we're talking about here are you referring to pressure losses caused by friction in the hoses
02:14:34 losses caused by friction in the hoses used to transport water from the hydrant to the pump appliance that's right now is it right that some degree of pressure loss is inevitable but this can be exacerbated by longer
02:14:46 but this can be exacerbated by longer hose distances and by bends and kinks in the hoses themselves correct to what extent did the long distance between some of the hydrants and the tower add to
02:14:57 the hydrants and the tower add to pressure loss on the night of the fire are you able to answer that scientifically if i can put it that way okay i mean it's clearly as you said there is a length of hose which uh it
02:15:09 there is a length of hose which uh it certainly impacts the the pressure head losses into that system and therefore it's extremely important to to set up like
02:15:16 like a tandem of pumping in other words you're boosting your pressure you have one appliance very close to the source of water to the hydrant which then pumps to another appliance and that was done on the northwest side but it wasn't done
02:15:29 on the northwest side but it wasn't done on
02:15:30 on on the east side on the on the hydrant h3 which was on granville road and bomber road uh until very late into the incident and that had a significant impact i mean uh the empirical evidence
02:15:42 impact i mean uh the empirical evidence for us is that this probably for that particular uh uh had an impact of probably another two three hundred um liters per minute flow rate into the pump appliance
02:15:53 pump appliance now
02:15:54 now we can see just to give a bit of a practical example if we turn to chapter five of your report which we can find at istrp
02:16:03 istrp quadruple zero trouble zero six forward slash twenty one
02:16:10 uh we can see at a line seven onwards uh a section describing the deployment of the ground monitor on grenfell walk and if we turn over the page to page 22
02:16:23 and if we turn over the page to page 22 and beginning at line 17 you say this and what i think is a practical illustration the point you've just made
02:16:30 just made but what your report says is this as with alpha 213 tl this low flow rate was because of the flow discharge characteristics of the fire hydrant and the long length about
02:16:42 fire hydrant and the long length about 115 meters of fire hoses between fire hydrant h3 and pump golf 272 the pressure losses in the long length of fire hoses between fire hydrant h3
02:16:55 of fire hoses between fire hydrant h3 and pump golf 272 reduce the flow into the tank of pump golf 272 by around 20 of the available flow rate from fire hydrant h3
02:17:08 hydrant h3 consequently the setup of a pump relay between fire hydrant h3 and pump golf 272 at around 0-600 hours increase the flow rate in the tank of
02:17:20 increase the flow rate in the tank of pump golf 272 from about 1200 liters per minute that's 20 liters per second to approximately 1500 liters per minute
02:17:32 approximately 1500 liters per minute 25 liters per second or
02:17:35 or about
02:17:36 about 86 percent of the ground monitors rated flow rate of 1750 liters per minute or 29 liters per second
02:17:46 second now there's a lot of technical detail in that quote but is the key point that the long length of hose needed to correct the hydrant of the pump appliance over 100 meters away had the effect of
02:17:57 100 meters away had the effect of reducing the flow rate by about 20 percent or so correct
02:18:02 correct and you also note in this paragraph that at about 0 600 hours the lfb was able to mitigate these losses by setting up a pump relay and first of all what is a
02:18:13 pump relay and first of all what is a pump relay it's a way to push the pressure within that sort of system of delivering the water for firefighting so pump relay will be
02:18:24 firefighting so pump relay will be you have multiple pumps which might be uh for example in series on parallel depending whether you want to boost your pressure or flow rate in that particular case uh
02:18:34 case uh so if i want to boost my pressure to negate the impact of these pressure head losses you will be setting up this operation of pumps in series so you have the first pump pumping into that
02:18:45 the first pump pumping into that particular case in the reservoir of the second pump and that guarantees a higher flow rate into the second pump to then deliver the pump discharge pressure so it's a boost between the hydrant and the
02:18:56 it's a boost between the hydrant and the primary pump appliance that's right now the first three reasons you identified for the low flow rates relate to low flow rates extracted from hydrants
02:19:07 hydrants whereas this fourth one relates to losses in pressure between hydrants and pump appliances correct that's a fair summary isn't it correct is it a first summary of your analysis
02:19:18 is it a first summary of your analysis to say that while these losses between the hydrants and pump appliances were also a significant factor the principal cause of the low flow rates was the low flow rates extracted from hydrants
02:19:30 flow rates extracted from hydrants that's right thank you
02:19:34 thank you i'd now like to move away uh from some of these technical matters and to look at the role of thames water itself now chapter seven of your report gives a
02:19:45 now chapter seven of your report gives a detailed chronology of the actions taken by thames water and its employees throughout the incident including communications and other interactions between thames water and the lfb is that
02:19:57 between thames water and the lfb is that a first summary of chapter seven correct that
02:20:02 that chapter
02:20:03 chapter was based on your review of evidence including statements and documents provided to the inquiry by thames wharton the lfb and transcripts of calls between thames water and lfb personnel
02:20:14 between thames water and lfb personnel is that right correct now the lfb first made contact with thames water by telephone at 0-128 is that right that's right
02:20:25 that right that's right and we can see an extract of the transcript of that particular call at i s t r p
02:20:32 s t r p quadruple zero trouble zero nine forward slash nine
02:20:41 and we can see it line seven to 10 of the table in the top half of that page that the lfb made a request for a water technician to attend
02:20:52 technician to attend and for thames water remotely to increase the pressure is that a fair summary that's right and if we stay in this chapter but turn to page 95
02:21:05 we can see at paragraph 25 that before 11 a.m thames water deployed a total of six network service technicians nsts
02:21:18 technicians nsts to attend the instant ground at grenfell is that a fair summary that's right and you refer to the first two
02:21:25 two as nst1l
02:21:28 as nst1l and
02:21:29 and nst2d for delta who arrived at 0 to 15 hours
02:21:35 hours nst 4n n for november and nst 3a who arrived later at about zero four fifteen and finally nst5m for mother and
02:21:48 nst5m for mother and nst-6r who arrived at about zero seven thirty hours is that right that's right now can i
02:21:56 now can i next turn to control interventions affected by thames water and if we can stay in this chapter but go to page 85 and in particular section 7.8.1
02:22:09 and in particular section 7.8.1 of your report now you say in subparagraph 1 that thames water carried out two control interventions on the night
02:22:20 the night first of all so we understand basic terms
02:22:23 terms what
02:22:24 what is your understanding of a control intervention
02:22:30 this is a very broad term but in that particular case means the opening of a valve and these are specifically manually operated gate valves
02:22:41 valves now you identify two control interventions first of all the opening of district boundary valve dbv214263
02:22:53 which connected pressure reduced area pbarht08
02:22:59 with a neighboring pressure reduced area pbar
02:23:04 pbar ht07
02:23:06 ht07 through a hundred millimeter pipe at about zero three zero nine hours and the second intervention was and i quote the opening of district boundary valve dbv214521
02:23:21 which provided an additional hydraulic connection within pressure reduced area pbar ht08
02:23:28 pbar ht08 through a 100 millimeter pipe at 1105 hours
02:23:33 hours now
02:23:34 now a district boundary valve is a valve which connects two different areas of the water network essentially is that correct
02:23:42 correct this is correct and i think it will be really helpful if we can bring some of the schematics i have in in chapter six if we can take it really visualize this i think if we just take it stage by
02:23:53 i think if we just take it stage by stage doctor stolen off for these purposes
02:23:55 purposes now is the rationale for opening boundary valves between different areas to increase the pressure and or reduce the energy losses in the target area by connecting it to another
02:24:07 target area by connecting it to another part of the water network which has its own inlet from water sources thereby spreading pressure losses uh more broadly across a larger area that's the intuition but this is just an
02:24:19 that's the intuition but this is just an intuition in in reality that decision cannot be made just by eyeballing a valve and making that decision that decision is to be made based on a more rigorous hydraulic analysis on the operation of the network
02:24:33 analysis on the operation of the network now
02:24:34 now it's really flowing from that point if we can take things again stage by stage can we go
02:24:39 can we go stay on this page page 85 and look at line 22
02:24:47 and you say this the hydraulic analysis carried out in chapter 6
02:24:52 chapter 6 indicates that the opening of the two district boundary valves by twul had minimal
02:24:58 minimal no material impact on increasing the pressure of washout hydrant location h5 and consequently the opening of the two district boundary valves had minimal no
02:25:09 district boundary valves had minimal no material impact on increasing the flow rate from washout hydrogen h5 into the onboard tanks of the connected pump appliances namely pump alpha 241 and
02:25:21 appliances namely pump alpha 241 and later in the instant pump sierra one three polo one
02:25:27 polo one both of these interventions by twul were made in response to requests by lfb for an increase in the flow rate from washout hydrogen h5 the same conclusion can be extended to
02:25:38 the same conclusion can be extended to all four hydrants used by lfb to provide water for fighting the fire namely that the interventions by twl eg the opening of the two boundary
02:25:49 eg the opening of the two boundary valves by twul had minimal no material impact on increasing the flow rates from the four hydrants used by lfb into the onboard tanks of the connected pump
02:26:00 onboard tanks of the connected pump appliances now in layman's terms you conclude that thames waters actions on the 14th of june resulted in no material improvement in the water supply
02:26:13 material improvement in the water supply provided to the lfb's firefighting equipment as a lay summary would you accept that i do and that is based on the analysis you carried out using the mathematical model of the water distribution network which
02:26:25 of the water distribution network which we discussed earlier in your evidence that's right now can we look at other actions taken by thames water and in particular the actions taken by the network service technicians i'm going to call them nsts
02:26:39 technicians i'm going to call them nsts now if we can turn over the page to go to page 86 of your report and if we could look at paragraph 4 which is at the head of that page
02:26:50 page there you describe two further actions taken by the nsts during the incident a between approximately zero six hours and zero six thirty hours four nsts
02:27:03 and zero six thirty hours four nsts assisted with cleaning drains which were causing flooding around grenfell tower and preventing lfb firefighters from gaining safe access to the building and b
02:27:13 b at approximately zero six thirty nst four n n for november fully operated a hydrant in use by lfb most likely wash out hydrant h5 after noticing it had
02:27:25 out hydrant h5 after noticing it had only been opened half a turn this action increased the flow rate from around 380 liters per minute the flow rate reported by watch manager beel
02:27:37 rate reported by watch manager beel to a flow rate of 450 liters per minute to 500 liters per minute the flow rate reported by station manager payton
02:27:49 manager payton now
02:27:50 now again in lay terms does that mean that the washout hydrant was like a half open tap with a reduced amount of water coming out of it before the nst noticed it and fully opened it
02:28:02 it and fully opened it correct and i refer to my previous comment it's because that hydrant was not inspected by lfb was not what we called exercised etc most likely the stem of that valve
02:28:14 stem of that valve uh couldn't couldn't operate fully uh might have jammed at that point and that was noticed later by the network service technicians we'd open it a little bit more nevertheless the total flow
02:28:25 more nevertheless the total flow coefficient of this hydrant remains very low
02:28:29 low now
02:28:31 now given your conclusion about the minimal impact of opening the boundary valves is it right to say that this action by nst 4n was likely the most effective intervention by thames
02:28:43 most effective intervention by thames water in your view during the incident in terms of increasing the flow rate
02:28:52 i i mean this is where i i really struggle to to drive a conclusion without referring back to the hydraulic model you know these are actions taken by the
02:29:04 you know these are actions taken by the network service technicians without understanding the hydraulics of the system and that's that's not something we expect from them to know in great detail that's the kind of the roads of
02:29:15 detail that's the kind of the roads of the network management center and we've seen from these examples that they received no feedback and guidance from the network management center to run these what if scenarios and provide a
02:29:26 these what if scenarios and provide a competent engineering knowledge of these control actions so in the end of the day the control action was pure improvisation on on on behalf of this network service
02:29:37 on behalf of this network service technician uh to the best of his knowledge but that improvisation was uh had no impact and secondly um he would have no knowledge to to judge what
02:29:49 have no knowledge to to judge what impact that would have had can we leave that topic and come on to a separate one which is the communications between lfb and thames water it's linked to the points um you've made
02:30:01 you've made now
02:30:02 now i put this broadly in chapter seven you criticize the quality and substance of the communication between the nfb and thames water
02:30:10 water the summary of your point can possibly be most usefully found at page 93. in this chapter
02:30:25 if we look at paragraph 21
02:30:30 you say this and forgive me for reading it out but it's possibly quite useful to bearing in mind what you've said communication between lfb and twl's nsts
02:30:41 and twl's nsts occurred on an ad hoc basis and consequently the communication was qualitative imprecise and lack technical rigor
02:30:50 rigor lfb control instant command did not articulate quantify and communicate their water supply and flow rate needs to the twl's nmc so network management
02:31:01 to the twl's nmc so network management center that you referred to earlier such quantitative requests could have included
02:31:07 included a
02:31:08 a a clear statement about the required flow rate for a particular appliance eg the aerial appliance of the east side requires a flow rate of 2 400 liters per minute 40 liters per
02:31:20 2 400 liters per minute 40 liters per second
02:31:21 second how can this be achieved and then if we can turn over the page looking at little the first little b at the top of that page
02:31:32 page you say lfb request could also include the following periodic updates by the lfb control to twul's network management center
02:31:43 to twul's network management center as the mobilization of appliances with significant water flow requirements progressed such updates could have included the required water flow rate on the instant ground eg lfb requires x liters per
02:31:56 ground eg lfb requires x liters per minute in this area and this includes an aerial appliance on the east side of grenfell tower 2400 liters per minute a gram monitor on the south side about 1900 limited liters per minute
02:32:08 1900 limited liters per minute a water supply to the dry fire main
02:32:11 fire main between about 1600 to 2000 liters per minute these are the approximate locations of the mobilized appliances and equipment can this flow rate be achieved and how paragraph 22
02:32:25 achieved and how paragraph 22 furthermore excuse me twl's nsts do not appear to have requested clear quantitative indications of lfb water supply and flow needs which if not forthcoming from lfb
02:32:39 needs which if not forthcoming from lfb nsts could have proactively requested themselves now having set that out um would you agree that your suggestions here amount to a council of perfection
02:32:52 here amount to a council of perfection and you cannot safely comment on whether it was operationally feasible for the brigade or indeed thames water to have detailed quantitative discussions given everything that was going on on the far
02:33:04 everything that was going on on the far ground
02:33:05 ground i disagree with that assessment i mean we know very well from for example watch manager bill and a lot of the statements first of all they had
02:33:16 of the statements first of all they had very good understanding of the flow requirements for their appliances they also knew exactly where they're connected certainly they could describe that so that information presents an
02:33:29 that so that information presents an opportunity to really kind of have the kind of dialogue i'm describing that on the other hand it's very common uh i mean i work with many water utilities in england
02:33:41 water utilities in england their incident management procedures include the hydraulic modular that's hydraulic modularism standby for that purpose to be able to simulate particular demand conditions on the
02:33:52 particular demand conditions on the network and very quickly provide a guidance
02:33:55 guidance and that guidance is also taken into account fire incidents such as this one in that particular case i see no examples that any forms of hydraulic modelling has been carried out from
02:34:06 modelling has been carried out from these discussions and any consideration of any data available to temps water to that telemetry system was taken into account so um so i don't uh i don't
02:34:17 account so um so i don't uh i don't agree with that assessment pushing it slightly further obviously you've made a number of observations on the effectiveness and efficiency of the communication and
02:34:28 and efficiency of the communication and coordination between the the brigade and twul
02:34:33 twul now
02:34:34 now would you accept that those are largely matters of operational and organizational competence for those bodies which don't obviously fall within the scope of your own experience and expertise
02:34:46 experience and expertise uh yes i broadly agree with that statement
02:34:49 statement however we also cannot decouple the car of the hydraulics what we observe without taking into account some of these human factory interactions and uh as someone who has work uh both
02:35:03 and uh as someone who has work uh both as an academic and researcher and practitioner into the war industry in the uk for over 20 years i find this highly inadequate to have that level of discussion to define key requirements
02:35:15 discussion to define key requirements for
02:35:16 for making incident-based decisions but the points you raise are points which you would actively encourage both the lfb and thames water to consider carefully
02:35:28 consider carefully i think they're absolutely essential if both of this organization needs to provide safe and secure supply of water for firefighting yes now can we turn to page 102
02:35:39 page 102 of this chapter
02:35:43 where you discuss alternative control options that were potentially available to thames water on the 14th of june and you set out four in particular at paragraph 45
02:35:54 particular at paragraph 45 they include the following increasing the pressure in pbar-ht08 by switching on the hammersmith pumps and turning off the pressure reduction control
02:36:05 control for pb ar ht08 i would call that just 0 8 just for clarity increasing the pressure in 0 8 by turning off the pressure reduction
02:36:17 turning off the pressure reduction control for example bypassing the pressure reducing valves or fully opening these valves c
02:36:24 c opening boxed closed inlets such as dm that's delta mother 18631 d the utilization of multiple hydrants to provide
02:36:35 to provide water for fire fighting now could we go through each of those four options briefly in turn
02:36:42 in turn first you refer to the option of switching on the hammersmith pumps now
02:36:46 now just remind those following we saw earlier that the hammersmith pumping station was one of the available sources of water um in the barrow hill zone uh the water network area in which the
02:36:58 the water network area in which the tower was
02:37:00 tower was was found is that right that's good act would i would appreciate if you can keep to one of these figures because
02:37:08 because it can tell fully the picture what i'm trying to convey okay we just go through so
02:37:13 so deal with the basics first now if we look at paragraph 46 on this page the normal cycle in june 2017 which was also followed on june on the 14th of
02:37:25 also followed on june on the 14th of june was that these pumps operated during the day but were automatically turned off at some point between zero zero thirty hours and zero zero forty five hours
02:37:37 hours and zero zero forty five hours before being automatically turned on again at zero five thirty hours is that right correct now in layman's terms can you help us why would turning the hammersmith pumps back on
02:37:48 back on during that time have increased the water supply to the lfb because again we are we are discussing here marginal gains cumulative gains into the
02:37:59 into the increasing the pressure into the network and that as we discussed might have a small impact on the on the discharge of water into the into
02:38:10 on the discharge of water into the into from the fire hydrants but nevertheless we need to put that into the context if that discharge of additional three four five hundred liters per minute on a ground monitor allows us to reach another three floors
02:38:22 another three floors that have a a significant impact on the night now that's why is the the reason why i'm trying to raise this issue is that uh the system continued to be pressure reduced throughout the incident
02:38:34 pressure reduced throughout the incident and in my view there is absolutely no justification for that pressure reduction to continue during that particular incident bear in mind your reference in answer there to marginal gains yes
02:38:47 there to marginal gains yes are you able to say how significant a difference turning on the hammersmith pumps would have made to the flow rates delivered from the four hydrants to the firefighting equipment i would i would be able to
02:38:59 i would be able to based on the figures which i present to demonstrate what the pressure at the inlet to these pressure managed areas is and would be that certainly i can do that and equally
02:39:10 that certainly i can do that and equally by turning off the pressure reduction
02:39:14 reduction system in place we can quantify how much extra pressure there will be at this particular hydrants and then with regards to the impact of pressure and discharge i would be able to tell you
02:39:26 discharge i would be able to tell you how much additional flow rate we can get from these hydrants by doing that particular control intervention bearing in mind your reference to marginal gains can we look at mata's adjectively is it
02:39:38 can we look at mata's adjectively is it fair to say that any increase would have been modest at best that's right that's a fair assessment it'll be modest but another 10 meter of pressure hat would have
02:39:50 10 meter of pressure hat would have increased as i said again the flow rate with the current with with the existing use of hydrons but another two three uh liters per minute and again if that means that marginal gain refers to
02:40:03 means that marginal gain refers to another two or three floors of impeding the spread of fire to me that was the price worth paying can we look at the second option you refer to in paragraph 45 on page 102
02:40:16 refer to in paragraph 45 on page 102 and that was switching off the pressure reduction in control pressure reduction control which was in place at the time now if i can just deal with some basic propositions first doctor sternoff first
02:40:27 propositions first doctor sternoff first of all the tower was situated within the pressure managed area is that right that's right so there normally if we just take that's right that's right good secondly a pressure managed area is an
02:40:39 secondly a pressure managed area is an area of the water network in which water companies reduce the water pressure to reduce the risk of water leaks and pipe bursts is that right they don't reduce the risk they reduce the leaks because it's again or if it's
02:40:51 the leaks because it's again or if it's discharged thank you and if we could go to istrp quadruple zero treble zero eight forward slash two three one
02:41:08 we can see at the end of line 11 going through to line 13 you concluded that the pressure reduction scheme in operation during the grenfell tower fire resulted in a
02:41:19 grenfell tower fire resulted in a reduction of pressure of between 7 to 13 meters
02:41:23 meters or differently 0.7 to 1.3 bar throughout the incident is that correct correct
02:41:33 is that the basis for your conclusion which we touched on earlier that one of the reasons for the low flow rate extracted from hydrants was quotes the continued pressure reduction in the water distribution system by thames
02:41:45 water distribution system by thames water
02:41:47 water correct but again this is the marginal gas that was relatively you know even that sort of 1.3 bar has a small impact but then if you take a small impact from the
02:41:58 you take a small impact from the pressure reduction plus small impact increasing the pumps and etc that marginal game suddenly becomes more more tangible and more beneficial for the fire brigade particularly in a situation when you're trying to really
02:42:10 situation when you're trying to really maximize both your equipment resources outreach etc i think
02:42:17 i think you've impliedly given the answer to this question but i'll ask it explicitly to
02:42:21 to get the benefit your evidence does it follow that turning off the pressure reduction control during the incident would have resulted in a corresponding increase of 7 to 13 meters or 0.7 to 1.3
02:42:33 increase of 7 to 13 meters or 0.7 to 1.3 bar and pressure that's my estimate yes
02:42:38 again you've been very fair in saying we're looking here at marginal increases again would that increase in pressure have been at the modest end
02:42:50 in pressure have been at the modest end of the spectrum that's right but
02:42:54 but you have to take that into into two particular directions one of them is the use of the hydrants is used by london fire brigade and the other one i say demonstrate it if
02:43:05 i say demonstrate it if london fire brigade with the guidance of times water we started using multiple hydrants that would have had much bigger impact now in relation to each of these two
02:43:16 now in relation to each of these two options we've been discussing turning on hammer sift pumps and turning off the pressure reduction control you observed in your report that thames water did not follow those options
02:43:28 water did not follow those options because of concerns that the resulting increase in pressure could lead to pipe bursts and we don't need to go to it but it's istrp quadruple zero trouble zero nine four slash 101.
02:43:40 nine four slash 101. now
02:43:41 now if we can go and look at that may i just say that there were two conflicting if we can weigh statements if you can just wait rather wait for the question rather than giving the answer to a question
02:43:52 than giving the answer to a question that
02:43:53 that hasn't yet been asked can we go to istrp quadruple zero trouble zero nine forward slash one zero
02:44:02 six and if we could look at section 7.8.7
02:44:09 which as you see is under the emboldened headline the risk of pipe breaks from turning on the hammersmith pumps and or turning off the pressure reduction control
02:44:19 control you conclude if we look at line seven there was a minimal risk of pipe breaks from turning the pumps on at hammersmith pumping
02:44:30 the pumps on at hammersmith pumping station and turning off the pressure reduction control in zero eight this is the pressure uh managed and so oh wait that's the pressure managed area in which grenfell tower is found is that
02:44:41 in which grenfell tower is found is that right
02:44:43 right that's right yes sorry that's the point i should have put to you earlier um just so we absolutely clear about terms that have been used here pipe breaks and pipe bursts are
02:44:54 are synonymous terms aren't they they're describing the same thing yes now your reasoning to support this conclusion is found in the next paragraph
02:45:04 paragraph and essentially to summarize the position and please disagree if i've not done this fairly or completely a the pipes have been in place for a number of years before the pressure
02:45:16 number of years before the pressure reduction areas were introduced meaning they already had a track record of operating successfully without pressure reduction secondly that the increased pressure would still have been within the rated
02:45:29 would still have been within the rated or recommended levels for those pipes 82 percent of which were relatively new have i fairly summarized your reasons for the conclusion which we've just looked at
02:45:40 which we've just looked at that's right i mean the network is was fairly new it was part of the uh victorian um renovation mains program temps water has been running for a while uh and that's
02:45:52 been running for a while uh and that's very unique in a way we had on we had pipes uh high-tested quality polyethylene pipes with age less than 10
02:46:03 polyethylene pipes with age less than 10 years so they were certainly uh within the
02:46:07 the very much the pressure rating within the pressure operating there but the other thing is that the pressure managed scheme was only implemented in april 2017 or two months before the actual
02:46:18 2017 or two months before the actual incident so uh if if the pipes have been operated under this conditions for good eight ten years there's no reason certainly to believe that by turning back to the to the
02:46:31 that by turning back to the to the pressure management conditions which were in place just two months ago suddenly will increase the the risk of pipe values now bearing that in mind would you agree that increased pressure in the neck in
02:46:42 that increased pressure in the neck in the network that would have resulted from turning on the hammersmith pumps or turning off the pressure reduction control
02:46:49 control would have increased the stress experienced by pipes in the network which brought a risk even if small of causing a burst in the more vulnerable parts of the network which had older unreplaced pipes
02:47:03 again i'm just referring that clearly these pipes were subjected to this kind of stress just two months before the fire and the other things you have to bear in mind that uh one phenomenon
02:47:15 to bear in mind that uh one phenomenon which haven't accounted for is during the pumping the operation of these pumps as we discussed they were continuously on and off that certain discharge was creating a huge level of pressure
02:47:26 creating a huge level of pressure transients into the system itself so so as a result of that we these pipes had already been subjected to quite a lot of stress and my engineering judgment having dealt with a lot of pipe failures
02:47:37 having dealt with a lot of pipe failures is that would be that the risk is actually minimal to to go back to a pressure management scheme which was in place just two months ago just bearing in mind the question that you were asked
02:47:49 you were asked um would you accept that the increased pressure from turning on hammersmith pumps turning off pressure reduction control would have brought a risk even if small of causing a burst in the more
02:48:00 if small of causing a burst in the more vulnerable parts could i have an answer to the question uh yeah how can we quantify this well i think it was put to you as small would you accept that yes
02:48:12 would you agree that a burst in one of the distribution pipes could have led to the loss of substantial volumes of water and wider spread at depressurization of the surrounding network
02:48:24 the surrounding network yes
02:48:25 yes and would you agree that such an event occurring on the night of the fire would have put at risk the entire water supply to the tower correct
02:48:36 now the third alternative intervention option
02:48:39 option you identified at page 102 and if we could go back to that page please
02:48:47 apologies for jumping around to start enough
02:48:50 enough and you identified there we can see it line 10
02:48:54 line 10 little c
02:48:55 little c opening boxed closed inlets such as dm18631
02:49:01 again a technical term but is the opening of a boxed closed inlet similar to the opening of a district boundary valve which we discussed earlier with the key difference that while the
02:49:12 the key difference that while the boundary valves opened by thames water simply connected the water network at the tower to other areas which are also undergoing pressure reduction and here you refer to the opening of a valve or
02:49:23 you refer to the opening of a valve or inlet which would have helped to bypass the pressure reduction that's right but can i just again point out that
02:49:32 that in my uh correspondence with times water and questioning times water we receive two contradictory statements one of the statements was very clearly
02:49:43 statements was very clearly identified by times water that pumps could have been turned on and pressure reduction could have been turned off but the request for that was not received so it seems that
02:49:55 that was not received so it seems that temps water contradicts its own assessment post grantfold that one of the responses yes we could have done it we just didn't get the request and the second request is second version of
02:50:07 second request is second version of events or
02:50:09 events or explanation was supporting the log book on the night of the fire which basically says we pursue uh perceive a higher risk of pipe burst if we actually implement this control
02:50:21 we actually implement this control operation in place so even from a point of view of thames water it seems that there is a lot of contradiction and again these are issues which we very difficult for us to assess i don't think anyone could really assess small risk in
02:50:33 anyone could really assess small risk in that space that's possibly a matter for the paneling due course now the final option you refer to in paragraph 45 on page 102 is the utilization of multiple hydrants
02:50:44 is the utilization of multiple hydrants to provide water for firefighting now that refers to the use of more than one hydrant to supply a single pump appliance uh to maximize the flow rate delivered from the network to the pump
02:50:56 delivered from the network to the pump appliance am i right about that correct would you accept that thames water staff aren't experts in operational firefighting presumably you do absolutely
02:51:07 absolutely would you accept that thames water staff
02:51:11 don't have detailed knowledge the workings and setup of pump appliances and other firefighting equipment can i just again the caveat is probably not i would not expect the network service technicians to have that
02:51:22 service technicians to have that knowledge but i would expect the network management control center to actually have that knowledge or at least have some understanding of how this provision of water for firefighting can be done
02:51:33 of water for firefighting can be done with the utilization of multiple hydrants
02:51:38 and when you say some understanding yeah i mean the request is to extract large volumes of water from your water distribution network and
02:51:49 distribution network and that's a subject to a again running a hydraulic model with a specific loading condition and and it's a very computationally efficient way to do it one can do it literally within a few minutes
02:52:01 few minutes would you accept just looking at it slightly differently that thames water are not well placed to advise a fire and rescue service on what equipment to use how to deploy it
02:52:12 what equipment to use how to deploy it etc
02:52:14 etc uh i i
02:52:16 uh i i so yes and i totally agree with the overall gist of that message but equally as an operator if you get a request for increase in pressure etc my engineering
02:52:28 increase in pressure etc my engineering kind of
02:52:29 kind of training would would prompt me to ask questions what exactly do you want how much do you want what flow rate do you want and etc these are very basic engineering questions to ask to quantify
02:52:41 engineering questions to ask to quantify so that i can assess to what extent my system can respond to that and advise you accordingly and really your criticism's focused on asking those basic questions isn't it and nothing more than that that's right
02:52:53 more than that that's right can i turn now on to a separate um topic which is
02:52:57 which is an assessment of higher flow rates and whether they could have been achieved and to this end can we go to istrp
02:53:07 istrp quadruple zero trouble zero eight forward slash two one six
02:53:19 and if we can look at line eight explain
02:53:25 explain your assessment in the following terms this assessment investigates whether a higher water flow rate could have been provided from the water distribution network based on the mathematical modeling of pressure and flow in the water distribution network
02:53:38 water distribution network using the validated hydraulic model of the water described in this chat the analysis for this assessment includes the formulation of an optimization problem which selects an
02:53:49 optimization problem which selects an optimum number of fire hydrants for lfb to connect to in order to deliver target water flow rates from the water distribution network to efficiently 100
02:54:00 100 utilize firefighting appliances and equipment
02:54:04 equipment the formulated optimization problem considers the hydraulic flow and pressure conditions in the water distribution network the available fire hydrant locations the discharge characteristics
02:54:16 the discharge characteristics flow coefficients together with the control settings of pressure reducing valves
02:54:21 valves prvs
02:54:23 prvs at the inlets of the water distribution network as decision variables now the rest of sections 6.8 explains in far greater detail how you carried out the assessment in
02:54:34 how you carried out the assessment in broad term how you carried out the assessment in broad terms is it right to say that the assessment used mathematical modelling to calculate whether given the hydraulic conditions on the night of the
02:54:46 hydraulic conditions on the night of the fire there was an optimum combination of hydrants that could have delivered greater flow rates to fire fighting equipment that's right now
02:54:56 now the results of the assessment are set out at the top of page 226 in this chapter which i'd be grateful if we could go to
02:55:07 and we can see at the top of the page you say this starting at line three one
02:55:13 one it was possible to achieve a flow rate of
02:55:16 of 7460 liters per minute that's 124 liters per second without changing the control settings for the pressure reduction scheme on the 14th of june 2017
02:55:29 scheme on the 14th of june 2017 providing that lfb utilized multiple hydrants for eg fire hydrants 1 3 8
02:55:37 8 4 and 7.
02:55:40 4 and 7. 2.
02:55:41 2. it was possible to achieve a flow rate of 12 000 liters per minute that's 200 liters per second by changing the control settings for the pressure reduction scheme on the 14th of
02:55:52 pressure reduction scheme on the 14th of june 2017 and providing that lfb utilized multiple hydrants eg fire hydrants 1 2
02:56:01 2 3
02:56:02 3 4
02:56:03 4 5
02:56:04 5 7
02:56:05 7 8
02:56:06 8 11
02:56:07 11 13
02:56:08 13 and 14.
02:56:10 and 14. now taking the step back from that that seems to show and please say if this is not a correct summary that your modelling showed that a total
02:56:21 that your modelling showed that a total flow rate of 7 400 liters per minute could theoretically have been achieved without turning off the pressure reduction in the network or alternatively 12 000 liters per
02:56:33 or alternatively 12 000 liters per minute if the pressure reduction had been turned off is that fair that's right and for context the peak flow rate actually delivered on the 14th of june 2017
02:56:45 the 14th of june 2017 was about
02:56:48 was about 4320 liters per minute is that correct that's right could we go to page 218 in this chapter please two one eight uh mr canoe can i just ask you we've got
02:57:00 uh mr canoe can i just ask you we've got sorry on the page we've just left um
02:57:05 it suggested that the lfb could have used what
02:57:10 used what 10 hydrants yes that's right um how far away would they be from the site of the fire would it be worth looking at the little diagram i'm trying
02:57:21 looking at the little diagram i'm trying to find if i can be given the reference to the map of the area
02:57:26 so so uh just for contacts clearly here what we've done we use the mathematical model which simulates the distribution of flow and pressure and also the formulation of this optimization problem
02:57:37 formulation of this optimization problem to say
02:57:39 to say find
02:57:40 find given the flow coefficient we assume that we know the flow coefficient of hydrogens that's why it's so important given the flow coefficient of hydrogens extract that maximum flow rate with a minimum
02:57:52 maximum flow rate with a minimum distance to hydrants so that was the formulation of the optimization right but equally one does not need to run that more sophisticated optimization problem one can go and just
02:58:03 optimization problem one can go and just pick up hydrants and say i'm going to fully open that hydrant and if i get these things what impact does it have and that's the kind of the importance of having this technical knowledge and analysis available in almost near real
02:58:16 analysis available in almost near real time which i see no reason why thames water couldn't have performed that duty the other option is what happened on the night where as i highlight in chapter 7 there is this complete mismatch of communication
02:58:29 this complete mismatch of communication you know you have a representative than the london fire brigade says give me more pressure and at the same time you have a technician of from
02:58:39 from thames water who looks in in their mindset pressure in the network it's it's pretty good and they say we can't deliver any more and then the intuition of making the decision on the behalf of
02:58:50 of making the decision on the behalf of the fire rescue services we can't get any more flow so let's just keep whatever we're doing could i go to the diagram just before the break if it would help you so well i'd just be interested to see it to be honest um could we go to istrp
02:59:03 honest um could we go to istrp quadruple zero trouble zero six forward slash six
02:59:08 slash six which should give us figure 5-2 and if that could be expanded um if it's more helpful i have the solution of this specifically with the diagram of hydrants which were
02:59:19 diagram of hydrants which were identified into i don't have the report in front of me but certainly there was a diagram well it might be given the time sir if we could see the particular diagram we
02:59:30 we could see the particular diagram we can find the diagram to which dr sonoff's referring and maybe draw it up uh when we return it to yes would that be convenient yes all right well dr strong enough we'll look at the diagram but after lunch all right
02:59:42 at the diagram but after lunch all right so we'll stop there we'll resume please at two o'clock and again while you're out of the room please don't talk to anyone about your evidence or anything relating to it all right very much thank you very much
03:00:02 thank you mr claire two o'clock thanks