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DPF guidance from the CPA

The Greater London Authority issued its “London Best Practice Guide Control of Dust and Emissions from Construction and Demolition” on the 21st November 2006.

This includes the requirement to retro-fit diesel particulate filters (DPFs) on certain types of construction equipment if it is to be allowed on to "high risk" construction sites in London, including the Olympic and Thames Gateway projects.

Other large UK cities are currently considering establishing similar requirements.

Powered access equipment and telehandlers are exempt while mobile cranes will require expensive 'active' particulate filters while crawler cranes will need 'passive' filtration.

The CPA has published a guidance note (the key points of which we publish below) to help those crane companies that want to work on these sites, deal with the issue.

The fitting of DPFs is complex and the guidance outlines the predicted practical problems, gives advice on approaching the suppliers of DPFs, outlines the technical differences of DPFs and the commercial pitfalls that need to be considered.

The guidance also lists the categories of equipment that will require DPFs. However, this list is still subject to change. The CPA is challenging the list on the basis that the retro-fitting of some categories is either too costly, too impractical or just not commercially feasible.

The list will be revised and published on the Energy Savings Trust's website by the end of January or possibly later.

CPA Guidance - Practical and Commercial Issues of Fitting Diesel Particulate Filters to Construction Plant


1. The Greater London Authority issued a London Best Practice Guide Control of Dust and Emissions from Construction
and Demolition on the 21st November 2006. This has three requirements in Section 5.2 that affect construction plant
used on selected sites in London. The requirements in this BPG are:
• some non-road mobile machinery (NRMM) with power outputs of over 37kW should be fitted with diesel
particulate filters (DPFs) conforming to a defined and demonstrated filtration efficiency;
• where a bunkered fuel supply is available, all NRMM should use fuel equivalent to ultra-low sulphur diesel
• all NRMM should comply with either the current or previous EU staged emission standards. Current standards
for engines 130 - 560kW are at Stage IIIA (or Euro IIIA). Engines 75 - 130kW are currently at Stage II and will
move to Stage IIIA from 1st Jan 2007. Engines 37 – 75kW will move from Stage II to Stage IIIA from 1st Jan

2. The BPG classifies sites as low, medium and high risk with different requirements for each:
• Low Risk - NRMM must use ULSD where available.
• Medium Risk - NRMM must use ULSD where available.
• High Risk - as for low and medium risk;
- exhausts must be fitted with DPFs;
- engines must conform to Stage II or Stage IIIA.

3. It will be up to each individual London Local Authority to decide whether they want to apply the requirements of the
BPG or not.

4. The CPA and its members, like everyone else, want clean exhaust emissions. However, we have argued against the
requirement to retro-fit DPFs on plant at this time mainly because, in London, the heavy costs far out way the
miniscule improvements in air quality that can be achieved where sites are surrounded by London traffic. We also
have argued that it is the wrong time to introduce DPFs since there is new and improved technology being developed
and coming on to the market. Since DPFs are being introduced on a piecemeal basis in London only, the problems for
plant hire companies are far greater than if the DPFs were introduced at the same time as the rest of Europe when
Stage IIIB is implemented from 2011 onwards.

5. Despite making our case in the strongest possible terms and supporting it with evidence from independent reports and
studies, the GLA has decided to keep the three above requirements in their BPG. The GLA has monitored London
traffic over a long period of time and proved conclusively that there are high levels of carbon particulates generated by
London traffic. They have monitored only one London construction site for a brief period of time and even this, their
own study, indicated that emissions from the plant on that site had an imperceptible affect on the overall particulates in
the area of the site.

6. The GLA’s have made their decisions despite the serious concerns of plant hire companies, contractors and plant and
engine manufacturers. CPA members now have to accept DPFs are required on “high risk” sites in London. Other
large cities are already considering introducing similar requirements in the very near future. It is therefore necessary
for each plant hire company to decide whether it is commercially feasible for them to supply plant to these London
sites at this particular time. This document is to help CPA members start this process. It may also help when
considering future purchases of plant and equipment.
Guidance on the Practicalities of Retro-fitting DPFs

1. As from 21st November 2006 onwards, tenders submitted for the hire of plant on selected “high risk” sites in London
need to include the retro-fitting of DPFs. The period between the tender stage and work starting on site is estimated
to be about 9 months or more, so plant hire companies will receive enquiries for retro-fitted plant to be delivery to high
risk London sites in late 2007 or early 2008.

2. There are two types of “wall flow” DPFs, active and passive. Passive DPFs can be fitted to any exhaust that achieves
a sufficiently high temperature to burn off the carbon particles as they are trapped on the filter.

3. If the plant has a variable work cycle and/or long periods of idling, the exhaust temperature may not be sufficiently high
enough to burn off the particulates trapped on the filters. Carbon particles will build up quickly and back pressure
increases which can lead to damage to the engine. To overcome this problem “active” wallflow DPFs must be fitted.

4. Active systems need to be “regenerated” from time to time as the carbon particles build up. Regeneration is carried
out using electric heaters or raw fuel heaters to burn off the particles. If regeneration is not carried out at the right
time, engines will be damaged. All plant can be fitted with active wallflow DPFs but they are much more expensive
than passive systems.

5. Many DPFs can be supplied with catalysts that are added to lower the burning temperature of the carbon particles.

6. Most passive wallflow DPFs can only operate efficiently when the engine is fuelled by ULSD. The main contractors
will be responsible for supplying and storing ULSD on the construction site. They must be made aware that, if this fuel
runs out, most plant with DPFs will not be able to continue to operate on ordinary red diesel.

7. It will initially be very difficult to obtain red ULSD on any other sites in London or outside the London area. However,
white ULSD will be mandatory across the country from 2008 and red ULSD will probably be more widely available at
that time as the refineries get geared up.

8. When active DPF systems have to be fitted in hired plant, automatic and continuous regeneration systems will almost
certainly be required. Without automatic regeneration the driver or operator must stop the machine to regenerate the
DPF at the required time. Often, the driver will not be the employee of the plant hire company. Furthermore, the driver
is always supervised by the contractor who demands high productivity. The driver therefore cannot always be relied
upon to regenerate at the appropriate time.

9. Deliveries to site of retro-fitted plant will have to be planned well in advance. In the case of emergencies, it will be
difficult for plant hire companies to be flexible and to deliver quickly to sites and contractors should be made aware of
this. Some DPF suppliers (but not all) say that their systems must be designed specifically for each make and model
of plant. It will probably take a week at the very least to get the system designed, to get it deliver it to a depot, to retrofit
it and deliver the machine to a site.

10. Some DPF suppliers will only deal directly with the original plant manufacturers when requested to fit systems, rather
than through the plant owner. This ensures that any warrantees will not be compromised.

11. Wallflow DPF systems are very expensive costing anything from £2000 to £10,000 to purchase and retro-fit depending
on the size of the engine, (see more details in “Commercial Considerations” below).

12. There is a new British electrostatic technology for removing particulates from exhausts that overcomes many of the
problems associated with wallflow DPFs. The manufacturer (Per-Tec, Manchester) of these “particulate matter
reduction devices” claims that, potentially, they could be fitted to all plant. They also say that they are much cheaper,
smaller, work with any fuel, do not cause back pressure in exhaust systems and do not rely on a hot exhausts to work.
They have been fitted successfully to buses, taxis and forklifts. Testing has only recently been started on construction
plant and the technology appears to be very suitable.