Anatomy of Petrol Leakages

INCIDENT INVOLVING PETROLEUM SPIRIT TANKER WESTONING, BEDFORDSHIRE

a t On Sa call was day 11th September 1976, ur , eived at Bedfordshire Fire reC t 1 Kempston, at 0715 hours, Service Con "Something has blown the caller High Street - the whole up in Wes h t" The officer in charge st f o reet the is a . t flrs 19 . pliance despatched ap . en still t wo mlles to the incident, saw wh . a l arge pall of smoke and from Weston1ng . ' from the centre of the flames r1s1ng . t an asslstance message for village and sen f ' appliances and men. additional lre On . 1 arr1 va , he was confronted with a " serl0US f" lre S 1" tuation of a petroleum spirit tanker which had overturned blocking the road and burning fiercely. He described what he saw as a "fire ball". Houses and shops on both sides of the village s tree t were also involved in fire . Persons were reported as being missing from some of these premises and a search procedure for casualties was immediately put into hand by firemen wearing breathing apparatus. At 0749 hours the Cbief Fire Officer arrived and took command. Extinction was achieved by the use of high expans i on foam onto the tanker and six water jets on the premises involved. A water carrier was sent on to supplement water supplies .

Petroleum spirit vapour had entered utility service ducts and the surface water draining system. This was ignited and minor explosions lifted a number of inspection covers in the locality. Public utility services were quickly on the scene and assisted in locating the run of drains and cable ducts which Fire Service personnel, assisted by a petroleum officer from the County Consumer Protection Department, continuously monitored for any petroleum spirit vapours with combustible gas detectors, until the initial danger was passed. Further checks were carried out for a period of 36 hours. Over 100 persons were temporarily evacuated from their homes in view of this risk.

The unsafe condition of the firedamaged buildings made the search for casualties most hazardous and it was not until 1022 hours when the "stop message" was sent that it could be safely assumed that all persons who were known to be in the vicinity at the time of the incident were accounted for.

In the circumstances it was fortunate that the driver escaped from the vehicle was not incapacitated and was able to details of the tanker's loan 1mmediately Th to Police and Fir e S . erV1ce. o e tanker was loaded with 22,000 litres f petroleum spirit carried in 7 compartments. Due to weight restrictions on the tanker, three of these compartments were only partially loaded and one was empty. When the tanker overturned the rear compartment was fractured, allowing the petroleum spirit to leak on to the roadway. Within seconds the vapour was ignited . The resultant fierce fire heated up the empty and partially loaded compartments, causing an explosion within a few minutes. The whole of the load was consumed in the fire, which destroyed 80% of the aluminium shell of the carrying tank. Ten properties, including the three main shops of the village were involved; six were severely damaged by fire and 21 persons made homeless. A rest centre was set up in the village school and the homeless, and persons temporarily evacuated, found shelter until alternative arrangements could be made. Apart from the driver of the tanker, who was slightly injured, no other casualties resulted. A fire appliance on route to the fire overturned and two firemen received injuries which necessitated hospital treatment and a subsequent period off duty. The last fire appliance left the scene of the incident at 11-15 hours on Sunday the 12th September.

It is apparent that the vehicle turned on to its right (off) side and slid approximately 20 metres in that position. Heavy scoring of the shell of the end section of the carrying tank resulted from contact with the road surface The end compartment (No.7) was f;actured and allowed eum spirit to be released. ThiS 1S confirmed by a witness's account of the front petrol being sprayed on to of a house. Another witnesS whO waS travelling in his car towards the tanker, reported that the tanker ThiS stopped before flames were seen. is confirmed by the fact that th:iS driver had time to climb out of d ignite· cab before the vapour waS ble Having established that the prob a origin of the fire was the . tankerd' assume then the supposed cause 1S to be:the rts Heating of component pa . be tanker caused by frict10n of n twee ·t· g overturned tanker and roadway ig n1 1n petroleum spirit vapour .

ANATOMY OF PETROLEUM

LEAKAGES By P. Robinson, Senior Fire Prevention Officer Buckinghamshire Fire Brigade.

Whilst it can be said that in the main the Petroleum Officer's job is straightforward for 95% of the enforcement task for which he may be responsible, there is no doubt that on occasions the resources, facilities and the patience of the operatives concerned, can be more than taxed by t he periodic requirement ,to deal with situations which usually start with an innocuous report of "a smell of petrol". Two such occurrences have recently occupied Buckinghamshire Fire Authority who are the enforcing authority for the County, within weeks of each other. A detailed account of one of these incidents is recorded here, since this type of incident does give rise to an important question at the end, which Association Members may care to try and answer in subsequent editions of The Bulletin .

I ncident No . l - Elf Service Station, Chesham - Leakage into River Chess

Dur ing a routine visit to Greenhams Builder s, Miner al Lane, Chesham on 10th Febru ary , 1977, an interceptor in the dra inage of a pe trol eum installation was foun d by an Inspec t ing Officer , to be con taminated with a heavy non-spec i fied oil , t he inter cept or was adjacent to a river outfal l . On 14th February , 1977, a c all was r e ceived f r om Chiltern District Council, t o t he effect t hat they h ad recei ve d a c all f r om Messr s . Greenhams Limi ted compl aining of a str ong smell f e t rol ne ar the river at the rear of premises and their office. ThiS comp l aint was lnvest1gated by an Ins p of 2 t1 ·n e c % on g Of fice r who an MSA Mode l r e cor ded r eadings t he previous l y men t10ned r 1ver outfall at an A . d 1n furth the of er vis f ice of th it on t he . e buildi . foll owl n ng g d f a irm y . · W1 t pre h s e Supervisory a e of Petrole nc Off1cer . . um s p1rl . r e t vealed t he .. con t 1nu1ng i n thi s ar ea by both s mell, explosi meter con fi r mation . a . was s et up on 16th February between mee t1ng · B· ade Thames water Authori t y, F1r e r 1g , . · t . t Council an d Coun ty Councll D1S r1C . . Highways r e presentat1ves Slnce the re were s n 1 petroleum i evera e ar vicinity and s nsta urfa l c lations e drains i n t lea he di ng to the river outfall wer e known to be extended over a wide ar ea . The on-site investigations by membe rs of the above , led to the discovery that the drains which eventually connected to the river outfall, did not in fact connect. to the suspect oil filled interceptor but , in fact, ran parallel to it and had connecting spurs to Elf Service Station a warehouse and a tyre depot in to serving Greenhams. At this stage, a bulk delivery of petroleum spirit was by Messrs. Greenham, and this was stopped by the Petroleum Officer and a 24 hour nitrogen pressure test required to be carried out on Messrs . Greenhams s i ngle tank and suction line. In the meantime, further investigations were carr ied out into the connecting drain s purs and interceptors at Elf Service Sta tion and Fitches Gar age also in the near vicinity , all proving satisfactory until a manhole cover over a drain which passed under the sales ki osk office of Elf Service Station was lifted and a rich (over 100% LEL) pe troleum vapour reading obtained on the explosimeter. As a preli mi nary investory measure, t he Group Manager for Elf Oil (G. B. ) Ltd . , was advised to have i mmediate tests carried out on t he suction lines be t we en h is pumps and tanks and to t ake pump 3 out of acti on s i nce this was showing sign s of l eakage within the casing . The subs equent s ite i nvolvement fo r the Li cens ing Authori ty , i s s et out f r om her e on in chronologi cal order, s ince t his gives a bett er picture of the extent t o which the various Inspec tors who bec ame invol ve d in thi s ongoi ng pr oblem , f ound t heir time monopolised .

Thursday, 17th February, 1977 0900 Tank for Messrs. Greenhams Limited was put on 24 hour nitrogen pressure test. 0930 Explosimeter readings taken in office of Elf Service Station and at the river outfall - significant but low readings taken. 1145 Explosimeter readings again taken at office and river outflow. 1200 Discussion and enquiries pursued with

Elf Service Station employees revealed losses of up to 40 gallons of petroleum spirit reported in three tanks. Manhole covers to six tanks lifted and petrol vapours pronounced in tanks 1,2 and 3.

Friday, 18th February, 1977 0900 Tank and suction line at Messrs Greenham, Mineral Lane, Chesham found satisfactory after 24 hour nitrogen test. 1100 Pump Maintenance Engineer arrived on site to check suction lines at Elf Service Station. Safety measures taken, forecourt roped off, no smoking notices placed, extinguishers sited to be accessible.

Suction pipes to pump 3 were tested first, since this had shown in the pump Signs of leakage. Engineer commented that bolts connecting suction lines to pump, were only finger tight. Leakage also noted between suction lines.

Tank 2 suction line tested and satisfactory.

Tanks 4 and 1 suctl" I" " on lnes pre-surlsed and failed wet t " d " 'ests applle pressurlsed to 10 lbs " " fa "l d A . P.S.l and agaln 1 e . rea and Re " . g10nal Managers of Elf Servlce Station d " " " a vlsed of flndlngs and that site t "" 0 stay closed untl1 remedla"l action taken to replace suspect suctlon lines "

Saturday, 19th February, 1977 hou 0f no Explosimet r s, 1430 hou E. Greenham " " " slgnlf l cant er r eadin gs taken 0845 r s 1500 h ' ours . Offices checked w"th " 1 explos lme ter -reading not d e "

Sunday, 20th Febr uary, 1977

0900 Precautionar " y explos im t e e r " readlngs t aken - lnterCeptors a t Fitches Garage checked with explos i me t er _ nil reading. Monday, 21st February, 1977 0850 Inspector on site - interceptor at rear of Standard Tyre Depot inspected - no significant reading. Thames Water Authority visit site and confirm that high octane petroleum spirit found in sample of water taken from river and analysed, also bitumen, probably from tank. Partial use of site to be permitted using tanks 1 and 4 for sale of petroleum spirit. Tanks 2 and 3 isolated to public.

Tuesday, 22nd February, 1977 0900 Inspector on site. Pumps 1 and 4 in use since 0700 hours. Thames Water Authority representative on site - places dye in manhole of waterway in Elf kiosk/office. Dye subsequently enters river outflow. Water Authority suspect tank 4 since this had reacted peculiarly when water placed in manhole earlier in that water had bubbled as level dropped in manhole pit. Thames Water Authority wish tank 4 emptied through pumps then nitrogen pressure test to 10 lbs p.s.i applied. Matter discussed between Inspecting Officers and Elf Oil (G.B.) Ltd., Chief Engineer.

Wednesday, 23rd February, 1977 0900 Inspecting and Officer" Chief ttendance Engineer, Elf Oil, 1n a on site. petroleum 1000 Site closed for sale of spirit. W. Dunkerley & Co . T ddington , , e to effect Middlesex, in attendance h"ch had " lineS w 1 repairs to suctlon "neers SO . uS eng1 failed since prev10 that they h siteS committed on ot er "ority to were not able to give pr1

Elf problem.

Wednesday , 23rd Febr uary , 1977 taken i n Explosime ter readings . e "th off1C manhol e , manhole in line W1 D e placed i n 20% on 100% s c ale. Yl e in office . manho manhole , seen l n Authority water shortl y after. ge from " " " h s Gara ellml nate F1tc e h y have once t e s us pect l i s t Sl ction between ascertained no conne with current drains on Fitches leakage problem.