London school closed by sinkholes linked to disused mine workings.

A school in northwest London has been forced to close after a series of sinkholes that opened up in its grounds were found to be linked to disused mineworkings running beneath the site. The first hole appeared in a car park at Pinner Wood School in Harrow appeared in the summer of 2015, prompting Harrow Council to commission an investigation into the site by geotechnical consultants Peter Brett Associates. This survey used laser survey borehole equipment to determine the structure of the ground beneath the school and discovered a series of tunnels, believed to be abandoned early nineteenth century mineworkings, running through a chalk layer 20 m below the surface. These tunnels appear to be beginning to collapse, raising concerns about the safety of structures above them, which has caused Harrow Council to close the school indefinitely while attempts are made to remedy the situation. Lessons will be held at other education facilities in the borough for the time being; it is not yet certain when (or if) it will be possible for the school to reopen.

Digital model of the tunnels below Pinner Wood School. Harow Council.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

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Seven hospitalized after acid spill at New Jersey school.

Six students and a teacher have been hospitalized following an acid spill at Union High School in Union City, New Jersey, on Wednesday 20 December 2016. About four litres of acetic acid was spilled in the incident, some of which splashed onto the teacher, who was taken to hospital as a precaution, as were six of the 25 students in the classroom at the time of the incident, the others being assessed by a Union Fire Department hazmat team at the scene before being discharged.

Hazmat response vehicle at Union High School following the 20 December 2016 chemical spil. ABC7.

Acetic acid (or ethanoic acid, CH₃CO₂H) is the principle ingredient in vinagar, but at high concentrations is corrosive, and can cause severe burns. It also gives off irretant fumes that can aggrivate the eyes nose and throat, or at high enough concentrations cause damage to the lungs and respiratory system. 

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Series of controlled explosions carried out at UK schools.

A series of controlled explosions have been carried out by bomb disposal experts at schools in England and Wales over the past 24 hours after concerns were raised about the storage of a potentially explosive chemical, 2,4-­‐dinitrophenylhydrazine (or Brady's Reagent), which is used in some A-level experiments. The chemical is both flammable and an oxidising agent, and can become an explosive under some circumstances if not stored correctly, which has resulted in advice from the Department for Education to destroy any unsafely stored chemical on-site rather than risk transporting it for disposal.

The structure of 2,4-­‐dinitrophenylhydrazine. Wikimedia Commons.

2,4-­‐dinitrophenylhydrazine is only dangerous when dry, and for this reason CLEAPSS (The body which provides advice on laboratory safety to UK schools) advises that the substance be stored wet, inside a container which is placed within an outer container that also contains water. Schools are currently being asked to check the storage of any 2,4-­‐dinitrophenylhydrazine they hold and to contact CLEAPSS for advice if the outer container is dry, and under no circumstances to attempt to open an improperly stored container (2,4-­‐dinitrophenylhydrazine is a friction explosive, and any dry dust caught in a screw top could potentially ignite like a match).

A number of residents living in areas close to schools have complained about explosions being carried out without warning. More seriously, concerns have been raised that these incidents may reflect lowering safety standards in UK schools as part of the government's academies program, which aims to give schools more autonomy and control over areas such as budgets and syllabuses. Services provided by CLEAPSS were formerly provided free to all schools, but now have to be purchased in, and it is not clear what proportion of schools are now doing this (although advice on 2,4-­‐dinitrophenylhydrazine is currently available to all schools for free on the CLEAPSS website), At the same time concerns have been raised that many schools with leadership drawn from outside the science sphere may be cutting back on support in science departments, lowering the pool of available advice in areas such as chemical storage.

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