End of the cam?

Valve actuatorI spotted an article recently about moving away from mechanical cam-driven valves on engines to computer controlled rapid acting “electro-hydraulic-pneumatic actuators” permitting far more precise control of valve movements without the “part open / part closed” stage of their mechanical counterparts. Why is this innovation important? Simple – it appears to offer a 16-17% improvement in fuel efficiency at a stroke – or to put it another way, a potential 16-17% reduction in CO2 emissions from transport (and any other engine-driven process) if it was adopted worldwide.

Steam engineWhich reminded me about “cams” and changing technology- especially as I have one on my desk as I write this! In my youth (well, for my Engineering Workshop Theory and Practice A-Level) I made a vertical D-slide double acting steam engine which uses a cam to control which side of the piston receives the steam, and which side is open to atmosphere. Because of this, the piston drives in both directions, rather than requiring the flywheel to drive the piston back to the top for older single-acting cylinders – at the time a major improvement in steam engine technology. And, in time, this very simple mechanical gizmo made its way into petrol & oil engines as a simple way to control valve movements, and now, for the first time in literally hundreds of years, we’re now seeing a step-change on the technology.

And made me wonder. Given that a move from a simple but commonly used mechanical system to a precise electronic system can radically alter the fuel consumption of the engines of potentially every car, lorry, bus, boat, ship … etc in use on the planet, where else could a bit of lateral thinking make big changes to our efficiencies, resource use, waste, and emissions whilst permitting us to continue to enjoy our tech-rich lifestyles?

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UKCG Environmental Training Standard

The UKCG Environmental Training Standard  was published in July 2015, and recognises the leadership role that UK Contractors Group member companies play in driving best practice within the construction sector. It sets down the minimum training expected for individuals to undertake their roles on member’s sites to be able to demonstrate their competency through formal environmental training, including the CITB SEATS course.

This document sets down the standard of environmental training applicable to those who manage, supervise or undertake construction related activities as follows:

Site Managers (including those employed by supply chains):

  1. CITB SEATS+ Course (SEATS plus additional management modules); or
  2. A comparable external course approved by the UKCG Environmental Training Task Group; or
  3. An internally developed course that can demonstrate training outcomes comparable to 1 and 2 above.

The training must last a minimum of TWO DAYS, include a form of assessment, and a completion certificate. Refresher training must be carried out at intervals not exceeding five years.

Site Supervisors (including those employed by supply chains)

  1.  CITB SEATS Course; or
  2. A comparable external course approved by the UKCG Environmental Training Task Group; or
  3. An internally developed course that can demonstrate training outcomes comparable to 1 and 2 above.

The training must last a minimum of ONE DAY, include a form of assessment, and a completion certificate. Refresher training must be carried out at intervals not exceeding five years.

Site Operatives (including those employed by supply chains)

A relevant competency scheme card including the CITB Health Safety & Environment Test where required, and renewed as necessary.

Note – in July 2015, the UKCG and NSCC (National Specialist Contractor’s Council) merged to form Build UK. A list of the members of the new body can be found here

Polymer flocculation

Discharging turbid water with excessive levels of suspended solids is a serious problem for construction sites, particularly if it enters stormwater drains or a natural water body as it can seriously degrade the habitat of fish and other aquatic life, or cause silting and increase flood risk. As a result, to do so is an offense under UK legislation. However, whilst coarser particles can be readily removed by filtration or sedimentation, finer particles will often remain in suspension with the slightest water movement making them very difficult to remove without treatment.

Turbidity in water is measured using a nephelometer, which passes a light beam through a sample of water, and measuring the scattering at a detector set at 90 degrees to the source, reported as “Nephelometric Turbidity Units” or NTUs.

Flocculation is the process of using chemical agents (flocculants) to bind together small soil particles into larger ones (flocs) that are heavy enough to settle to the bottom of the liquid for removal. Introduction of positively charged (cationic) polymer macromolecules into turbid water attracts the naturally negatively charged clay particles, clumping into a floc having sufficient mass to sink to the bottom of the liquid. However, although cationic flocculants are highly effective in isolated systems, their positive charges make them toxic to aquatic organisms when dissolved in water, and they should NOT be used when runoff could enter stormwater drains or open-water bodies.

Anionic polymer flocHowever, anionic polymers, which carry a negative charge (like clay particles) are not toxic, and if added to stormwater together with positive calcium ions (Ca++) to form ionic bridges, anionic polymer flocculation will take place, reducing the turbidity of the treated water without harming aquatic life. Once the flocs have formed, provided the flow rate is sufficiently low, they should settle to the bottom of the water body ready for removal.

For polymer flocculation to be effective on site, three fundamental process must take place: chemical binding, settlement, and floc removal. To bind particles, polymers can be applied directly to soil surfaces, to water flowing in a collection channel, or into a settling pond, either through impregnated jute mats, hand or mechanical spreading of dry polymers, or direct application of liquid polymers. Following treatment, the objective is then to reduce the velocity and erosive force of the water by allowing it to spread out over a relatively level area, aided by perpendicular wattles, silt fences, and impregnated jute matting. Once settled, the sediment can be removed for reuse or disposal, and the now-clear water discharged to stormwater systems or open-water bodies.

Concretesock News – Laing O’Rourke

Concretesock Laing

Browsing through Laing O’Rourke’s Annual Review 2015, I came across this interesting little snippet on page 80:

“We have successfully implemented ‘concrete socks’ on a number of projects. These fit over the ends of concrete wagon chutes and negate the need for wash-out facilities on site. This not only saves money but significantly reduces the risk of environmental incidents. We will now look to extend usage across the business”

A little birdie also tells me that 19 socks are also successfully in use by Lafarge to service a major ISG contract in Sinfin, Derby …

Looks like this brilliant but simple idea I’ve been writing about for a couple of years is finally finding it’s feet.

Earlier articles by me on Concretesocks:

Bosch Cordless Metal Saw

Bosch metal sawBosch have introduced their first professional cordless metal saw – the GKM LI 18v Professional, which, thanks to a new “Standard for Steel” saw blade, cuts steel with speed, precision and virtually no sparks. Looking at the video, you can’t help but think that this is streets ahead of grinder-type cutters in terms of environmental and H&S impacts. According to the makers, the 2.7 kg saw has a 4Ah battery and can make in excess of 300 cuts in a 20mm pipe on a single charge.

Disposal of composite cladding panels

Composite metal-faced insulated foam cladding panels, also known as “sandwich panels” or “engineered panels” have become a common construction product since their introduction for cold stores over 40 years ago, and are now used extensively as external cladding systems for a wide range of buildings. With a design life of 30 years or more, many early panels (and buildings)EPIC cover 600 will be reaching the end of their useful life, and are likely to be subjected to extensive refurbishment and / or alteration, resulting in the need to dispose of unwanted panels.

However, this is not as straightforward as it may at first seem, as many early panels used CFCs and later HCFCs as blowing agents for the foams – gases which damage the ozone layer if released into the atmosphere (Ozone Depleting Substances, or ODS) – and as a consequence their release is strictly controlled by legislation; for example, the requirement that domestic fridges are recycled in an inert atmosphere and their ODS recovered for destruction. And in exactly the same way, those construction insulation foams that contain these same gases are also “Hazardous Waste” if the proportion of ODS exceeds the 0.1% threshold (see below) and must also be disposed of in a similarly controlled manner.

There is an industry guide to help identify and correctly dispose of metal faced composite foam panels (click on the image to go to the website where you can download the pdf guide) but here are a few simple rules to help identify foam insulation panels containing ODS:

  • If the insulation foam is polystyrene (PS) of any date, it does NOT contain ODS

For other insulation foams, such as polyurethane (PUR), polyisocyanurate (PIR) and phenolic resin foams (PF)

  • If the foam panel was manufactured before 1990, it almost certainly DOES contain ODS
  • If the foam panel was manufactured between 1990 and 2004, it MAY contain ODS
  • If the foam panel was manufactured after 2004, it does NOT contain ODS

If in doubt, the blowing agent can be identified by laboratory testing. However, even the newer (flammable) hydrocarbon blowing agents such as pentane are not free from problems as a recent EA report demonstrated, and since December 2012, all wastes containing hydrocarbon blown insulation foam must be consigned as Hazardous Waste to minimise the risk of explosions and fires at metal processing facilities.

For the relatively small number of ODS panels that have been discarded to date, the normal method of disposal has been to cut the panels up with a reciprocating saw into maximum 2m x 1m sections and dispose of them in one of the four domestic refrigerator recycling plants in the UK. However, with the commissioning of a new industrial-scale panel recycling facility capable of safely processing both ODS and pentane-containing foams, the need to carry out this labour-intensive operation has now been removed, and any panel that can be fit inside a 40-yard roll-on roll-off container can now be processed directly without size reduction.

The determination of ODS-containing foams as Hazardous Waste

Regulation (EC) 1005/2009 on substances that deplete the ozone layer sets down in Annex 1 substances that deplete the ozone layer, including a wide range of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Regulation (27) specifically states:

“Directive 2006/12/EC … and 91/689/EEC … provide for measures on the environmentally sound disposal and recovery of waste and controls on hazardous waste. In this regard, special attention should be paid to ODS in construction and demolition waste (my highlighting) and in equipment falling within the scope of Directive 2002/96/EC on waste electronic and electrical equipment (WEEE).”

This has been directly incorporated within the List of Wastes Regulations for WEEE waste with a specific entry in section 16 02 “wastes from electrical and electronic equipment” :

“16 02 11* discarded equipment containing chlorofluorocarbons, HCFC, HFC”

but no similar entry exists for construction wastes other than generalised references to “dangerous substances”. Reference to EA Guide WM2 “Hazardous Waste. Interpretation of the definition and classification of hazardous waste” indicates that on p.20, Risk Phrase R59 “Dangerous for the ozone layer” applies to substances that appear in Annex 1 to Regulation (EC) 1005/2009, ie a wide range of CFCs and HCFCs – the common blowing agents for earlier foams – and sets a Hazardous Waste Threshold Level of 0.1%. The waste type is therefore a “mirror entry” waste, and should the threshold be exceeded in a construction foam, the Hazardous Waste entry should be used when consigning waste. This guidance is repeated in Appendix C14 of EA Guide WM3 “Guidance on the classification and assessment of waste” against Hazard Statement H420 “Harms public health and the environment by destroying ozone in the upper atmosphere” with a similar 0.1% threshold.

For such materials, my choice of LOW code and expanded description for unstripped (whole) insulation panels containing threshold-exceeding ODS or hydrocarbon blowing agents would be:

  • 17 04 09* metal waste contaminated with dangerous substances (ODS or Hydrocarbons in foam)

and for stripped panels where only the threshold-exceeding ODS / hydrocarbon-blown insulation is consigned:

  • 17 06 03* other insulation materials consisting of or containing dangerous substances (ODS or Hydrocarbons)

Acoustic barriers

Echo Barrier 02Acoustic barriers are often seen as something to be used in town centre locations, positioned around the site perimeters to protect passers-by from noise pollution and minimise nuisance to neighbours. But, using such barriers within the site also reduces the risk of hearing  damage to operatives, and the need to wear bulky and uncomfortable hearing protection in hot weather. Many Echo Barrier 01systems are panellised and can be used to shield noisy items of plant and equipment within a site, preventing noise breakout, and resulting in a quieter and more comfortable working environment.

Use of such equipment away from town centres can also be beneficial for wildlife, reducing the risk of disturbance of protected species when working on sensitive sites, including nesting birds in early summer.

(Click on an image to visit the company’s website)

Chemical dust suppression

Dust suppression c1Dust on construction sites is a common cause of nuisance to neighbours. To reduce this, many sites damp down dusty surfaces during dry weather using large quantities of (normally) tapwater, which rapidly evaporates in warm, dry weather and needs to be replaced to be effective – often at a time when there may be increased stress on mains water supplies.

However, by adding small quantities of relatively harmless chemicals to the mix. the need to respray can be dramatically reduced. These chemicals fall into two main groups – hydroscopic minerals that both hold and reabsorb moisture, and chemical “glues” that bind particles together into larger clumps, making them less likely to become airborne.

Hydroscopic minerals such as calcium chloride are mixed with water during spraying, and if applied to previously damped surfaces, or after rain, rapidly penetrate 7-10cm into the ground. By absorbing moisture in the surface layers, they maintain moisture content, increasing the shear strength of the surface reducing dust and surface wear. In dry weather, the mineral will dry out to some extent during the day, but will reabsorb moisture at night. In wet weather, heavy rain drives the mineral deeper into the soil, but as the surface dries, capillary action will return the mineral to the surface, maintaining it’s effectiveness in variable weather. The product has been used by the quarry industry for a number of years, and has shown to be effective on heavily used haul roads for in excess of four weeks. In addition to it’s moisture retaining properties, calcium chloride is also a mild weed suppressant, but unless used at excessive concentrations, has little impact on local wildlife and ecology.

Chemical “glues” such as calcium magnesium acetate (CMA) are normally applied “waterless” by spreading with a modified grit spreader onto a clean surface. Rather than binding the soil surface to prevent dusting, they instead bind individual fine dust particles (such as PM10, and to a certain extent PM2.5) into larger clumps that are more resistant to airborne suspension, remaining on the road surface for dispersal on vehicle wheels or removal by road sweepers. Clearly, the effectiveness of such chemicals will reduce with time (depending upon the level of dusting present and the rate of dispersal on vehicle wheels) requiring regular reapplication to control dust in the longer term. CMAs have been trialled extensively by Transport for London since 2011 in attempts to reduce PM10 pollution in the capital, and with regard to environmental impacts in their report they state: “The TfL report stresses that CMA is non-toxic, presents no significant risk of corrosion and is harmless to plants and water supplies. The calcium and magnesium components, the report says, can ‘benefit’ soil, just as liming a garden improves permeability, while the acetate portion biodegrades naturally.

Clearly the two systems act in different ways, and understanding their effect would determine exactly which might be most useful on construction sites. However, as a rule of thumb, hydroscopic minerals such as calcium chloride appear to work well on absorbent surfaces such as haul roads by maintaining a damp surface and minimising surface breakdown, whilst chemical glues are effective on hard, relatively clean, infrequently swept surfaces subject to light residual dusting from vehicle movement such as tarmac access roads.

Prosecution – Statutory nuisance, Noise

On 7th November 2014 at Eastbourne Magistrates Court, the contractor working on the conversion of the old Co-op building on London Road in Brighton into student accomodation was found guilty of four charges of breaching Section 61 of the Control of Pollution Act 1974 and fined a total of £6000 with court costs of £3511.48 and victim surcharge of £120.00, a total of £9631.48.

Following earlier compliants, the council had limited working hours to 8.00am – 6.00pm Monday to Friday and 9.00am to 1.00pm on Saturdays. Despite this, residents complained of noise throughout the weekends, early mornings and late into the night, citing removal of skips at 6.30am, use of nail guns and saws running throughout Saturdays, and generators left on until 10pm at night. The chair of council’s environmental committee was quoted as saying “This company has given residents no respite, with noise from the site seven days a week causing considerable stress and disturbance. We had no hesitation in taking legal action to protect residents.” The company pleaded guilty to the offence but did not attend court.

The company was also convicted of two similar charges on the same site last year, with fines totalling £2900.

(This Case Study was abstracted from a Construction Index article published on 10 November 2014)

Dirtbags

Dirtbag 1There are times when you have no option but to pump out silty water, leaving you with no alternative but to treat it to remove the silt before you discharge it to a watercourse or sewer (with the relevant consents or permits, of course!). If your need is large enough, you can use settlement lagoons, or pieces of specialist plant, but sometimes what you need to do will be so minor that it doesn’t really warrant the expense and effort. Dirtbags offer a simple filtration solution that takes very little space – a large geotextile envelope that you pump the water through, leaving the suspended solids in the bag. The standard bag is 1.5m square, and according to the manufacturers, it can handle flow rates up to 4600 litres per minute. As the bags are manufactured in the UK, Dirtbags can be custom-made to suit site conditions or flow rates.

In my mind, they are a really useful primary control technique, removing the easily filtered particles, but secondary treatment (settlement, flocculation, etc) may be necessary to improve the water sufficiently to meet any suspended solids requirements of an offsite discharge consent. (The manufacturers have a separate webpage showing Dirtbags in use for primary filtration inside standard settlement tanks) They’re also really useful where you’re discharging to elsewhere on your site as part of a general silt management strategy to help you keep the discharge area clear of mud.

UtilityBagAnd if you’re in the utilities business, and you regularly face the challenge of dewatering ducts full of silty water before you can carry out your work, Dirtbags also make “Utilitybags” – a smaller sausage-shaped Dirtbag to fit over the end of the discharge hose to at least take out the larger solids before discharge to a road gully.

(To visit the Dirtbags website, click on any image)