Expert hydraulic engineer Dr. Sternoff testifies on water supply capacity at Grenfell Tower, revealing that the network could have delivered far higher flow rates than were achieved on the night. Evidence shows LFB lacked up-to-date knowledge of hydrant operational status.
00:00:26 would you ask dr stern enough to come back in please you
00:00:42 all right doctor still enough ready to carry on yes thank you thank you very much yes mr king yeah thank you um before the break uh doctor we were searching for a diagram which showed all the hydrants uh
00:00:53 diagram which showed all the hydrants uh we think we found the diagram to which you were referring and so could we look at uh i s t r p quadruple zero trouble zero eight forward slash two one nine
00:01:08 and if the diagram figure 6-114 could be expanded
00:01:32 so
00:01:45 sometimes these things take time don't worry
00:01:48 worry i appreciate this
00:01:52 thank you that shows i think the hydrants which we were discussing before
00:01:58 before lunch and i think in the center we see fh1 and immediately below that um is a circle with two um
00:02:08 um bits coming off it that's the private hydrant is that right uh correct just um first of all bought these
00:02:15 these figure shelves is the hydrants which within the area of grand fall tower all the hydrants which i considered in my analysis are within 300 meters from
00:02:26 analysis are within 300 meters from grenfell tower on this diagram and the assumption was that these hydrants could be accessed with a pump relay with a single pump relay very
00:02:37 pump relay with a single pump relay very much as uh lfb has done just a little bit more context to this diagram and the analysis clearly the diagram also assumes that and the analysis also assumes that
00:02:51 and the analysis also assumes that we have
00:02:52 we have some estimates about the flow coefficients of hydrogens which normally should be a regular practice of flow testing so that's one aspect and the second
00:03:03 so that's one aspect and the second aspect what it does it runs the analysis for
00:03:06 for um
00:03:08 um for loading conditions or for demand which first of all take into account the standard pda procedure of lab you know predetermined uh attendance procedure which includes a
00:03:20 uh attendance procedure which includes a single area of appliance for high-rise buildings so in other words what i assume for these 7 500 liters per minute is that i have one area of appliance of about 2 400 liters
00:03:32 area of appliance of about 2 400 liters per minute let's assume that they have to deploy also a ground monitor of about 1 600 liters per minute then there needs to be about 1 500 liters per minute for internal fire fighting so this is very
00:03:45 internal fire fighting so this is very much i would imagine uh a reasonable assumption to to us to assume that if a pda includes that appliances we need to
00:03:56 pda includes that appliances we need to have sufficient flow rate to fully deploy these appliances and that's why the 7 500 liters per minute come from for this first analysis the second thought
00:04:06 thought of my question some time ago now simply to confirm the diagram it is thank you
00:04:12 thank you can we i want us to return back to where we were uh doctor and deal with excuse me the assessment of whether higher flow rates could have been achieved i think some of the points you're adverting to now we can better
00:04:25 you're adverting to now we can better address in a more focused way as we go through that particular topic now could we go back to ist rp quadruple zero treble zero eight forward
00:04:37 quadruple zero treble zero eight forward slash two one eight
00:04:43 now this
00:04:45 this is an extract from your report and it sets out some points which are relevant to the assumptions that you made in the assessment which we were discussing before the break which you've been
00:04:56 before the break which you've been touching upon again
00:04:58 again and what
00:04:59 and what it sets out there under the heading 6.8.12 assessment two assumptions is this
00:05:08 this it is important to note the limitations for this assessment the estimated flow figures scenarios above the flow rates of 7 400 and 12 000 which the assessment tested are for
00:05:20 which the assessment tested are for illustrative purposes only to assess from the perspective of the water distribution network whether it would have been possible to supply those flow rates given the hydraulic conditions in the network
00:05:31 the network none of the above should be interpreted as any suggestion on my part as to which appliances or equipment lfb could or should have deployed on the night of the fire those being questions for beyond
00:05:43 fire those being questions for beyond far beyond my expertise and the scope of this report the assessment further relies on the following factors 1. lfb having up-to-date knowledge of the operational status and flow discharge
00:05:55 operational status and flow discharge characteristics of fire hydrants based on flow tests of fire hydrants this does not appear to have been the case at grenfell tower two
00:06:05 two lfb using multiple fire hydrants to supply water to individual aerial appliances eg lfb setting up pump relays as done for fire hydrant h8
00:06:17 as done for fire hydrant h8 three
00:06:17 three thames water twul providing expert engineering guidance and support to lfb including the use of a hydraulic model and near real-time
00:06:28 a hydraulic model and near real-time hydraulic telemetry data now in addition to the factors and assumptions listed there is it also important to make clear that you don't know about
00:06:39 you don't know about and cannot comment on whether it would have been logistically possible or operationally feasible for the lfb to have used the specific optimum combination of the specific ten
00:06:50 optimum combination of the specific ten hydrants identified by this assessment in order to achieve those flow figures correct
00:06:57 correct so for example some of the hydrants identified may not have been in operationally suitable locations due to access problems or other difficulties which are understandably beyond your knowledge and expertise
00:07:09 beyond your knowledge and expertise correct as i said this is an illustrative example of a process that analytics that could have been deployed this assessment was calculated using a complex mathematical model which you
00:07:21 complex mathematical model which you validated and refined following physical testing carried out after the fire is that right that is correct but i also have expectations that uh water utilities
00:07:32 expectations that uh water utilities should
00:07:32 should and and they do that sort of level of analysis on a regular basis now the mathematical modeling um you used also factored in the flow coefficients of the hydrants at
00:07:43 coefficients of the hydrants at near the tower which you were able to calculate following a series of tests you carried out in 2008 is that right 2018 18 saw apologies yes
00:07:54 2018 18 saw apologies yes and that data of course wasn't available to anyone on the 14th of june 2017. no but um that's absolutely correct but as an engineering judgment i can make a
00:08:05 an engineering judgment i can make a certain assumptions about these flow coefficients if i'm faced with with the need to run that sort of level of analysis
00:08:12 analysis whatever data was available at the time of the fire for quite proper reasons you're not in a position to comment on whether it would have been practically possible for thames water to carry out these kind of complex mathematical modeling and
00:08:24 complex mathematical modeling and hydrogen optimization calculations in real time in the midst of the incident in the early hours of the 14th of june 2017. would you agree with that proposition not entirely no
00:08:36 not entirely no let's take in stage what do you agree with then i agreed that running probably a complex
00:08:43 a complex optim formulating this is an optimization problem might have been beyond the scope and knowledge of thames water on the night of the fire but equally the problem what i'm describing could have been enumerated manually in
00:08:56 could have been enumerated manually in other words stamps water had access to a hydraulic model they had access to a near time telemetry coming from their system and that would have been sufficient to run the hydraulic model
00:09:07 sufficient to run the hydraulic model and manually almost pick up hydrants and demonstrate that larger flow rates could have been extracted they might not have been
00:09:15 been optimal
00:09:16 optimal as optimal defined in mathematical terms but they would have been far greater than what was achieved on the night of the fire
00:09:28 if thames water had been able for example to carry out an exercise in mathematical modelling and hydrant optimization calculations in real time in the middle of the instant
00:09:41 real time in the middle of the instant and we're indeed able to communicate the ideal combination of hydrogens to the lfb
00:09:48 that would likely have required the lfb to completely reorganize its water supply setup midway through the incident uh which obviously of itself would have caused disruption and delay again would
00:09:59 caused disruption and delay again would you agree with that proposition i i i agree that that would have required a bit to change their operational strategies but um i wouldn't
00:10:10 operational strategies but um i wouldn't go as far as stating that this would delay
00:10:13 delay activities so i don't know how that conclusion can be drawn that this would delay activities because if we looked and i'm just observing facts here by no means this is part of my competence but
00:10:26 means this is part of my competence but if i look at the statements based by insulin commander row and locklin
00:10:32 locklin they completely dismissed the row of the use of water in the firefighting operations but
00:10:38 but is it fair to say that looking at the assumptions you yourself have set out in the report and the limitations you've you've fairly concede there the answers you've again fairly given to
00:10:49 the answers you've again fairly given to the points i've put you just now that the results of the assessment about flow rates are what was theoretically could have been delivered from the water
00:11:00 could have been delivered from the water distribution network in optimum hydraulic conditions and they don't allow us to draw any safe conclusions about what flow rates the lfb and thames water could or should have achieved on
00:11:12 water could or should have achieved on the night
00:11:15 the night i guess yes
00:11:18 can i now turn to a separate topic just before we move away can i just also note that the analysis i carried out was carried out for peak demand that prompted me because the network
00:11:30 prompted me because the network management center of thames water raised cereals concerned that as demand picks up
00:11:35 up they will have significant problems so i i run that analysis on the worst case scenario which was the morning peak demand 8 o'clock in the morning thank you
00:11:47 thank you the next excuse me section i'd like to turn to is whether regulatory standards relating to the supply of water were met and
00:11:58 and for this purpose if we could turn to istrp quadruple zero treble zero five forward slash four eight
00:12:10 uh in this part of your report you provide uh usefully an overview of the relevant statutory and regulatory standards that apply to the provision of water i'd
00:12:21 that apply to the provision of water i'd like to go through those standards that apply to various aspects such as water pressure flow rate and the rest of it turning first though to water pressure you set out a paragraph two which starts
00:12:34 you set out a paragraph two which starts at line seven on that page this
00:12:37 this the water supply and sewerage services customer service standards regulations 2008 the gss regulations require a minimum pressure of 7 meters
00:12:48 require a minimum pressure of 7 meters 0.7 bar static head pressure in the communication pipe supplying premises with water off what
00:12:56 off what the water regulator also refers to quotes a reference level of service close quotes of 10 meter pressure
00:13:04 pressure on the customer's side of the main stop tap
00:13:09 tap due to the practical difficulties of measuring pressure there othwot suggests that water companies instead use a surrogate measure of 15 meter pressure head in the adjacent distribution main
00:13:22 head in the adjacent distribution main and this is common industry practice and if we could go to page 234 of chapter 6 which we find at istrp
00:13:34 istrp quadruple zero treble zero eight forward slash two three four
00:13:43 a paragraph uh six point nine point six you set out your conclusions in relation to the pressure levels on the 14th of june 2017 and we can see a paragraph 29 at the foot of that page this
00:13:55 at the foot of that page this i mathematically simulated the pressure heads at each hydrant used by lfb to supply water for firefighting on the 14th of june 2017. the lowest estimated pressure head is 25
00:14:08 the lowest estimated pressure head is 25 meters 2.5 bar for the fire hydrant h8 the pressure head at hydrants h1 a fire hydrant h3 a fire hydrant and h5 a washout hydrant
00:14:21 a fire hydrant and h5 a washout hydrant varied between 29.4 meters and 8 35.8 meters pressure head that's 2.9 bar to 3.5 bar and you go on to say these minimum pressure figures on
00:14:32 to say these minimum pressure figures on the 14th of june exceeded indeed comfortably exceeded both the 0.7 bar and the 1.5 bar regulatory standards is that a first summary of your position it
00:14:43 that a first summary of your position it is thank you can i now turn to water flow rate and for this purpose can we go to ist rp quadruple zero trouble zero five
00:14:54 ist rp quadruple zero trouble zero five forward slash four eight and if we could look at paragraph three in particular i don't think that's what we need
00:15:05 at the reference is trp thank you
00:15:10 thank you if we could look at paragraph three uh you note there that section 38 subsection one of the foreign rescue services act 2004
00:15:21 foreign rescue services act 2004 states that quotes a fire and rescue authority must take all reasonable measures for securing that an adequate supply of water will be available for the authority's use in the event of fire
00:15:33 the authority's use in the event of fire elsewhere in this chapter you note that and i quote the statute provides no further detail on what constitutes an adequate supply and there is no minimum flow rate figure
00:15:44 and there is no minimum flow rate figure explicitly stipulated in the fire and rescue services act 2004. now
00:15:51 now there is guidance i think you identify in your report and if we look and continue in paragraph three on the page that's on the screen we see at the end of line 21 you say this
00:16:03 end of line 21 you say this the national guidance document on the provision of water for firefighting recommends a flow rate of 20 liters per second to 35 liters per second that's 1200 liters per minute to 2100 liters
00:16:16 1200 liters per minute to 2100 liters per minute for multi-occupied housing developments of more than two floors such as grenfell tower now that's a long run up to a question which is looking at flow rate that was
00:16:28 which is looking at flow rate that was actually delivered to the tower we referred to this briefly and earlier in your evidence and can we go to page 231 of chapter six which is istrp
00:16:39 231 of chapter six which is istrp quadruple zero trouble zero eight forward slash two three one
00:16:46 and we can see at paragraph 14 you state that and i quote the estimated peak fire flow used on wednesday the 14th of june 2017 was approximately 72
00:16:58 14th of june 2017 was approximately 72 liters per second 4 320 liters per minute
00:17:04 minute apologies for a very long run up but necessary to this question the flow rate at grenfell comfortably exceeded the recommended flow rate in the national guidance document is that a fair conclusion
00:17:17 conclusion yes with a lot of caveats but yes but essentially yes yes now if we can go that sounded like a rather guarded reply you say with a lot of caveats what do
00:17:28 you say with a lot of caveats what do you
00:17:29 you i think perhaps possibly we ought to know what you say about that i i mean i find um a lot of these um documents there there first of all they're not not regulatory documents
00:17:41 they're not not regulatory documents they're they just provide recommendations in that respect and they have
00:17:48 have they have there's a lot of ambiguity between these numbers so if i take the number of uh the national guideline document for the provision of water first of all i've identified a number of limitations
00:18:00 i've identified a number of limitations gives a certain flow rate between 1200 to 2400
00:18:08 liters per minute so this is a very wide range at the same time that wide range it doesn't really seems to match the predetermined attendance again going back to my point that if the london fire
00:18:19 back to my point that if the london fire brigade has predetermined tenders to to deploy an aerial and as we learned from the press very recently they've purchased a whole set of new aerial other platforms does that mean that
00:18:31 other platforms does that mean that you're
00:18:31 you're you're purchasing a rolls royce and you're driving this rolls-royce in the first gear because purely you don't have the capacity to utilize that equipment uh and that's the kind of uh uh that's
00:18:43 uh and that's the kind of uh uh that's the caveats i want to put around there are these numbers but actually the meaning of these numbers it's hugely questionable right i was going to draw you now to the points which you
00:18:55 draw you now to the points which you would want to caveat that with so i was kind of looking into those questions now if we can go to is trp
00:19:03 is trp quadruple zero trouble zero five forward slash 14
00:19:07 slash 14 i think really i want to take you through the issues which you say the guidance document doesn't take account of but it should in order to provide i think a more satisfactory or tolerably reliable figure
00:19:19 tolerably reliable figure and
00:19:21 and in essence we can see from the the underlying subheadings on that page the facts and matters which you think ought to
00:19:30 ought to be
00:19:31 be accounted for which aren't first of all the size of the building secondly the building materials used and the extent of compliance with building regulations thirdly the presence of fire protection systems such as sprinklers and finally
00:19:43 systems such as sprinklers and finally whether or not an aerial appliance is required are those the points that the particular points which you feel the national guidance document ought to consider but it doesn't correct
00:19:56 the final matter i'd like to take you to is the quantity of water and compliance with regulatory standards in that regard and to this end can we stay in this particular chapter but go to page 48
00:20:12 and if we look at paragraph 4 at line 28 on that page dealing here as the subheading indicates with quantity of water is it right to say that quantitative
00:20:24 is it right to say that quantitative water is simply about there being enough in the system so it's not going to run out whereas flow rate is about how much water can be delivered at any particular given time correct
00:20:35 given time correct now your report addresses the available quality of sorry quantity of water on the 14th of june on page 229 of chapter 6 which we find at ist rp quadruple zero
00:20:47 6 which we find at ist rp quadruple zero trouble zero eight forward slash two two nine
00:20:53 and if we look at paragraph two the report lists the sources of water which supply the barrow hill zone uh in which the tower is found and a paragraph three further down the
00:21:05 and a paragraph three further down the page
00:21:07 page you say this the average daily demand for the barrow hill zone in 2017 was estimated at 116.58
00:21:18 116.58 megaliters per day or the equivalent of 80 958 liters per minute 1349 liters per second in comparison the maximum flow rate used
00:21:31 in comparison the maximum flow rate used by lfb for firefighting on the 14th of june 2017 did not exceed 4 320 liters per minute about 72 liters per second and this water flow rate for fire
00:21:43 and this water flow rate for fire fighting peaked at hours of minimum water consumption then if we go slightly further down the page to paragraph five you concluded thus the barrow hill zone had no water
00:21:55 the barrow hill zone had no water storage and or water availability constraints to be able to meet and significantly exceed the water demand for fighting the fire at grenfell tower now in your view therefore
00:22:06 now in your view therefore is it safe to say that the quantity of water available for firefighting was more than adequate yes definitely dr sternoff those are all the questions i have for you now um sir might i ask
00:22:19 i have for you now um sir might i ask for the usual break of say yes a quarter of an hour to see whether i've missed anything or to see whether any particular points that anyone else would like me to raise yes very well well dr stone enough when we get to this stage
00:22:30 stone enough when we get to this stage and council thinks he's asked all the questions he ought to ask we always have a short break to give him a chance to check that he's not overlooked anything and also to give other people who are following
00:22:40 following the proceedings from elsewhere the chance to suggest questions which perhaps ought to be put to you so we're going to break now we'll resume it 20 to 3 please
00:22:50 3 please and at 23 we'll see if there are any more questions for you okay all right thank you very much thank you
00:23:06 thank you very much mr canoe 20 to 3.
00:41:12 would you ask dr stone enough to come back in please
00:41:25 all right doctor still not let's see if there's any more questions for you shall we yes mr kinnear sir thank you for the further time i have no further questions for you dr stern officer it just leads me to say thank you very much for providing such a comprehensive report
00:41:37 providing such a comprehensive report and indeed a further supplemental report and pretending to give evidence today it's very very much appreciated thank you yes and he's right that i should say thank you as well dr stone on behalf of
00:41:48 thank you as well dr stone on behalf of three members of the panel you've done an awful lot of work on this matter with great care as we can tell from your report
00:41:55 report and it's been very interesting to have the chance to hear you in person as well so thank you very much we've benefited greatly from your evidence and we're very grateful to you for coming to give it so thank you very much for the
00:42:06 it so thank you very much for the opportunity as well thank you you're free to go thank you bye
00:42:15 yes mr kenya well that's all we have for today is that right that's right sir so we uh we shall finish at that point but tomorrow we have another expert witness coming to
00:42:28 another expert witness coming to give us his evidence and we should look forward to seeing uh him i think it is dr bisbee isn't it it is excessively professional yes tomorrow good and we'll do that at 10 o'clock tomorrow
00:42:39 and we'll do that at 10 o'clock tomorrow morning thank you thank you very much 10 o'clock tomorrow thank you
00:42:53 you