Although the following topic is not directly a landfill CQA issue we thought that it would be of real interest to many of our readers.

Compulsory site waste management plans (SWMPs) for construction projects over £300,000 in value, have been a legal requirement in England since April 2008, and are therefore needed for landfill works contracts. The intention is that the plans will forecast all waste produced on site and how much will be recovered or disposed of.

The SWMP should help businesses manage construction waste as part of a project rather than an afterthought. By planning for construction waste much earlier than has been the practice it should be possible to do much better in managing construction waste. Early experience that has been reported has suggested that in building projects it has been possible to achieve substantial savings which exceed the costs of producing and updating the site waste management plan.

A landfill site lining development or surface restoration project is undeniably a construction project, and almost all will exceed the threshold cost. Therefore, each project will need a site waste management plan, which starts with the designer and becomes the responsibility of the principal contractors on commencement of the work on site.

The regulations set out a range of offences relating to the failure to produce or implement a plan, punishable by a fine of up to £50,000 on summary conviction, or an unlimited fine on conviction on indictment.

On these landfill projects there will be little if any construction waste produced at all, apart from possibly some spoilt or unsuitable material, and the usual site facilities wastes. As ever, these otherwise laudable regulations make little sense in some applications, and in landfill in our view, we have such an example.

So how does a landfill contractor set about writing his site waste management plan after being awarded the contract and receiving the client’s design stage plan, for a landfill project?

What should the SWMP contain?

According to NetRegs, the level of detail that your SWMP should contain depends on the estimated build cost, excluding VAT. Their summary suggests the following:-

For projects estimated at between £300,000 and £500,000 (excluding VAT) the SWMP should contain details of the:

• types of waste removed from the site
• identity of the person who removed the waste
• site that the waste is taken to.

For projects estimated at over £500,000 (excluding VAT) the SWMP should contain details of the:

• types of waste removed from the site
• identity of the person who removed the waste and their waste carrier registration number
• a description of the waste
• site that the waste was taken to
• environmental permit or exemption held by the site where the material is taken.

At the end of the project, you must review the plan and record the reasons for any differences between the plan and what actually happened.

The contractor, or anyone else exporting waste from the site must still comply with the duty of care for waste.  However, because it will now be necessary to record all waste movements in one document, having a SWMP will help the site contractor’s management to ensure they comply with the duty of care.

For help in preparing your SWMP see the video on the Site Waste Management Plan hub page, or  Landfill Site Waste Management Plan page.

The use of a Geosynthetic Clay Liner (GCL) as the low permeability layer in landfill lining systems and restoration caps can provide a cost effective and readily Construction Quality Controlled alternative to natural clay. In fact this material may be the only option in regions where the local geology is such that no clay of suitable quality is available.

A GCL uses Sodium Bentonite, a dehydrated clay that has long been recognised as an ideal impermeable barrier material, and which will expand once in the soil to six or more times its initial volume.
Claymat is an example of this type of product which comprises a sandwich of bentonite between two layers of geotextile. The result is a thin, flexible (it arrives in rolls, clean, easily transported and installed) lining system. Finesse Claymat is as manufactured by ABG of Meltham, and there are a number of other manufacturers.

Layers of sand or fine gravel (150 to 300 mm) are often placed on top and/or below the GCL as specified by the landfill capping system designer to protect it from damage during installation or thereafter.

The GCL membranes on the market have been tested to provide both an excellent self-healing capability, and chemical resistance, and are accepted by most environmental regulators. A paper available from Thomas Telford Journals shows that permeability can be compromised if suitable treatment is not applied at overlaps, so clearly the CQA Engineer will need to take care about ensuring good site procedures on this matter. (See “Forensic analysis of excessive leakage from lagoons lined with a composite GCL”, At Thomas Telford Journals.)

Assessments of the environmental protection afforded by a landfill liner require that all underlying soil and geosynthetics components are considered in landfill contaminant migration assessments. The results described in a 2004 paper provides published data for laboratory GCL diffusion and sorption coefficients, required to perform contaminant migration assessments for five VOC contaminants commonly found in municipal solid waste leachate. Assessment of diffusion coefficients and clay-leachate compatibility assessment is also deemed necessary to ensure acceptable long-term performance. In fact GCL membranes were shown to give permeabilities generally significantly lower than those reported in the literature for compacted clay liner materials.

Pozidrain ground water drainage membrane is also often used in conjunction with a Geosynthetic Clay Liner as when laid above the GCL it reduces the hydraulic head and stress on the geomembrane and it also provides additional physical protection against puncture.

A significant number of landfill sites have already utilised the benefits of Geosynthetic Clay Liners and many use Pozidrain and equivalent products within these systems.

SITA Cornwall  News (January 2008) - reports: Improvement in compliance… Landfill

SITA Cornwall’s two landfill sites play an important role in managing the county’s waste. A great deal of work was carried out in 2007 at the landfills and even more is planned for 2008.

It was a busy year in terms of engineering at United Mines Landfill in 2007, with the construction of a new landfill cell, the diversion of a sewer and surface water system and the capping of an area of 600m2. The leachate plants at both United Mines and Connon Bridge sites were refurbished which assisted the significant reduction of leachate levels.

Local residents and councillors have joined a community liaison group at United Mines to discuss issues around the site and preparations have begun for an open day in spring.

The aim to cap a large area of United Mines and Connon Bridge confirms that major landfill construction will continue in 2008.

2008 will also see the temporary closure of the Connon Bridge Landfill site. Work has already commenced to improve the visual impact, increase gas and odour control and further reduce leachate generation.

Efforts will also be concentrated on reducing the sites’ impacts both on the local and global environment, with the development of a strategy to reduce the sites’ water and energy use.

(Clearly there will be plenty of Landfill CQA work in the region this year - Ed.)

This summer was the second summer season, and the 4th stage of restoration capping at this Wexford County Council landfill during which Rowe Environmental provided capping construction quality assurance services.

The start of the works in June 2007 coincided with the uniqely heavy rainfall exprienced throughout the region that month. Although clay capping proceeded in between rain storms, problems arose with clay compaction due to the very waterlogged conditions on the landfill.

Civil Engineering Contractor Roadbridge used every opportunity to work whenever the site dried out in between rain showers, and the project was remarkable for not being not seriously delayed. This was despite the need for additional harrowing and recompaction of the clay over much of the site, in order to reduce the water content to acceptable levels, and the un-programmed addition of extra soils reinforcement to steep slopes within the restoration area.

The final stage of restoration capping at Killurin is programmed for next year when the recycling facilities and replacement residual waste landfill at the Council’s new Holmestown Landfill will be operational, and the Killurin Landfill closed.

The restoration capping works we completed this year
were similar to the Stage 3 of restoration which took place
through the summer of 2006.
Click on the image below to view
the Landfill Restoration slideshow for 2006:

Summer 2007 saw the environmental engineering consultants Enviros Consulting return to Wexford County Council’s Killurin Landfill Site, for further capping and restoration works.

This year sees the penultimate stage, of a 4 year involvement of Enviros with local authority Wexford County Council at this active domestic waste Landfill site.
Wexford originally commissioned Enviros back in 2004 to carry out extensive extension earthworks works to stabilise slopes and increase the existing landfill capacity. Over the following two years, further works were carried out to place the final cap on completed sections of the site, install surface water management systems, place restoration soils to a finished profile and grass seed the area .
Steve Last, Principal Engineer and Project Manager heads up the project, with Rowe Environmental providing CQA supervsion.

Outstanding Beauty
Killurin Landfill which has been operational since the early eighties lies some 8 miles outside of Wexford Town, and bordered by the River Slaney to its south, in what is a most outstandingly beautiful part of Southern Ireland.
The views across the surrounding areas, from within the site are extraordinarily beautiful.

Walking around the site again this year, you get a real feel for the necessity and value of the restoration works which were done last year, as the grass seeding is well established, it looks green and very natural, and fits in with the local existing environs.

The views across the River Slaney are undoubtedly superb.

2007 Capping and Restoration Programme
This year a further 10,000 sq,m of landfill area will be capped with clay restoration soils placed and hydro seeded.   Capping materials, being a locally won “marl” type clay, that meets specification limits on density and compaction, found within 1000 metres of the site, has been most fortunate indeed, given the scarcity of suitable materials.

A Geo-drainage layer is to be incorporated in the above-cap drainage system linked to a surface water collection system, along with the construction of surface water outfall points.

Erosion control matting will be veneered between the sub-soil and top-soil layer. Improvements to the gas management systems are also required.
An initial twelve week programme is on a two week break just now, but continues in the second week in August 2007 and all of works are hoped to be complete by mid- September. weather permitting…………………….. of course !!