tunnelling underground space MSc Tunnelling & Underground Space Environmental management on site part 2

tunnelling underground space Contents 1.Materials management a)Materials procurement b)Material resource efficiency c)Storing materials 2.Construction activities and environmental risks

tunnelling underground space Materials selection and procurement think about environmental, social and economic impacts of: –material production –delivery –use on site –waste management eventual maintenance/refurbishment/ demolition/reuse

tunnelling underground space Materials management materials selection and procurement: –timber –aggregates and cement replacements –plasterboard and gypsum –PVC –formaldehyde –hazardous materials materials storage

tunnelling underground space Timber certification provides assurance of origin and that timber is from a legal and sustainable source Forest Stewardship Council (FSC) Programme for Endorsement of Forest Certification (PEFC) a certified chain of custody should be seen as a minimum most contractors only procure certified timber from sustainable sources as a matter of policy

tunnelling underground space Aggregates and cement replacements use of recycled and ‘secondary’ materials reduces demand for virgin quarried material and can be a cost-effective alternative (Aggregates Levy Tax) recycled aggregates, crushed concrete, asphalt planings, spent rail ballast, recycled glass secondary materials can be by-products, e.g. microsilica, pulverised fuel ash, blastfurnace slag, bottom ash, used foundry sand secondary materials can be unwanted mine or quarry spoil, e.g. slate aggregate, colliery spoil or china clay sand

tunnelling underground space Examples use of 50:1 PFA:OPC mix to backfill a tunnel, rather than foam concrete use of crushed concrete aggregates to backfill a shaft PFA or microsilica as cement replacements can result in better long-term durability and strength for structural concrete recycled glass sand for lower road base material (A3 Hindhead)

tunnelling underground space Plasterboard and gypsum new plasterboard should be stored flat somewhere they won’t be damaged and away from water to avoid it becoming waste! organise a take-back scheme so damaged boards and off-cuts can be recycled by the supplier gypsum and other high-sulphate wastes that are from demolition, or if mixed with other non- biodegradable waste, must go to a separate landfill cell where no biodegradable waste is accepted* * because high-sulphate waste mixed with biodegradable waste produces hydrogen sulphide, which is toxic and odorous link to EA websitelink to EA website

tunnelling underground space PVC (polyvinylchloride) PVC is safe to handle, but vinyl chloride, a toxic and carcinogenic gas, is used in its production and is leached out in landfills containing PVC it also contains phthalates, cadmium, zinc, lead etc, which are all hazardous substances vinyl chloride is found in the air and in groundwater near waste disposal sites and PVC plants concentrations 1000 times the index dose (minimal risk) have been found in the atmosphere near landfills and PVC plants

tunnelling underground space PVC continued Environment Agency advice is it is better to avoid the use of PVC where possible although PVC is difficult to ignite, fire/incineration may release chemicals that are hazardous – this is a contentious issue

tunnelling underground space Formaldehyde used as a bonding material in chipboard, plywood and MDF (medium-density fibreboard) unsealed chipboard can release measurable quantities into the air when MDF is cut, a fine dust is created that if respired can expose you to formaldehyde Exposure to even low levels of formaldehyde through inhalation can cause irritation to the eyes, nose, throat, mucous membranes and skin Formaldehyde-free and low formaldehyde containing boards and products are increasingly available in the UK and should be specified wherever possible

tunnelling underground space Materials assessments preferred – with reduced social/environmental impacts (e.g. FSC timber) advisory – not banned, but clients may prefer it not to be used (e.g. PVC) prohibited – banned by law (e.g. asbestos) increasingly, life cycle assessments of materials from cradle to grave are used – if in doubt, ask your Environmental Advisor or Environmental Manager

tunnelling underground space Materials resource efficiency Site Waste Management Plan can be used as a tool to minimise waste by early identification of opportunities for reuse or recycling by focussing on how materials are ordered, delivered, stored and handled on site, ways to reduce waste may be found packaging – too little and products are damaged and hence waste, too much and there is lots of packaging waste!

tunnelling underground space Materials storage away from sensitive receptors unlikely to pollute (e.g. bunded) secure from theft and vandalism protected from the elements not subject to double-handling easily accessible don’t stockpile more than you need – space is usually at a premium, and have dedicated areas for particular materials make sure containers are labelled clearly

tunnelling underground space Oil and fuel storage Oils Storage Regs (2001 & 2006) – all storage vessels must have secondary containment, i.e. –drip tray –bund –diesel bowsers usually double-skinned the secondary containment must be 110% of the capacity of the largest storage vessel or 25% of total volume, whichever is greater oils must be stored away from any watercourses (>10m) also >2m from any building or boundary

tunnelling underground space Construction activities and environmental risks 1.concrete batching 2.concrete pour 3.excavation of a shaft 4.new tunnel construction - general 5.repairs to a 200 year old canal tunnel

tunnelling underground space References CIRIA (2010). Environmental good practice on site. CIRIA Report C692 (Audus, I., Charles, P. & Evans, S. eds). London: CIRIA.