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.

Filtration Rolls and Wattles

Tensar Sedi-maxFiltration rolls and wattles offer a good alternative to straw bales for silt and erosion control on construction projects by intercepting and retaining suspended solids, and slowing water flow across a slope. Generally speaking the rolls are laid in shallow trenches, and are staked in place. As most products appear to be fully biodegradable, they can be incorporated into permanent works, and I noticed an interesting variation on this where the stakes were “living wood” (I assume willow) which subsequently sprouted as the rolls degraded.

Filtration rolls are more intended for permanent works, whilst straw wattles are more cost effective options for temporary works. Both of the Tensar products (SediMax-FRTM Filtration Rolls and SediMax-SWTM Straw Wattles) are fully biodegradable – the rolls filled with a straw/coconut fibre mix with a biodegradable netting cover, and the wattles with compressed straw cyclinders wrapped in a photo-degradable netting. Wattles are light and manhandle-able and easily staked along contours of disturbed slopes, wrapped around inlets and drains, along the banks of watercourses – in fact, across anywhere water is likely to flow on a construction site – a practical, controlled, and more long-lasting alternative to straw bales

(Click on the image above to go to the SediMax page on the Tensar site)

Silt Fencing

Silt Fence - HytexSilt management on UK construction sites is frequently limited to providing a wheel-wash at the site exit, but controlling silt movement on site can keep haul roads and access areas cleaner, minimising the need for such facilities. A useful tool in a silt management strategy for sites is the installation of silt fences in vulnerable areas to prevent silt running off sloping land onto areas you want to keep clean.

Silt fences are generally constructed of woven geotextiles, which are “heeled” into the ground to seal the bottom, and supported on timber stakes to hold them upright. Under heavy rainfall, silt-laden water is retained and filtered by the fence, keeping the silt in place whilst allowing substantially cleaner water to drain away. Once the rainy period has ended, the retained silt can be returned to the land from which it originated, and the silt fence is once again ready for the next period of wet weather.

Silt Fence DWInstallation can be by hand for shorter lengths, but on larger sites, mechanical installation is more practical, with attachments available for commonly used machinery.

Whilst silt fences are frequently employed to control silt run-off from open land in other sectors (such as forestry) as well as in construction, they are also useful for controlling dust-laden run-off from demolition operations, and around stockpiles of crushed materials.

(Click on any image to go to the relevant pages of the manufacturers’ website)