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10.2 Characteristics and Quantity of Municipal
Solid Wastes (MSW)

It is very surprising that the EIA report fails to provide an analysis of the impacts of waste characteristics or the availability of waste quantity on the operation of the proposed WTE Plant. These are central issues for a WTE plant as they determine the sustainability of continuous production of electricity from MSW, the characteristics of the various waste by products generated during MSW incineration and the process stability during the operational phase.

Even though the obligations to provide the quantity and quality of MSW are those of the GoM as indicated previously, these do not relieve the Promoters in ensuring that their Project is sustainable.

Thus the EIA report has the obligations to carry out an assessment on the MSW
characteristics and their availability.

It is enlightening that the EIA report did make reference to the waste characteristics reported in the Carl Bro report and quotes the findings of the Carl Bro report extensively, yet it fails to address the numerous reservations made by Carl Bro on incineration of the local MSW.

The EIA report states further that the Plant will not accept asbestos, inert construction waste and hazardous waste29. Since MSW already contains a hazardous fraction let alone the industrial component, the EIA report does not indicate the methodology it will adopt to prevent the hazardous wastes from entering the furnaces. Under a worst case scenario, i.e. with hazardous waste, the EIA report should have provided analysis on the impacts of this hazardous component on the resultant incineration by products.

The issues pertaining to the predicted quantity of solid wastes available in Mauritius and their characteristics have been elaborated in the previous sections and these lead to the conclusion that the over optimism expressed in the EIA report on the no/minimal impacts of the associated activities are at best doubtful.

10.3 Gaseous Emissions from the Proposed WTE Plant

Air pollution is a central issue with waste incineration due to the formation and release of many toxic compounds and metals resulting from incineration. The concentrations of the various pollutants are strongly dependent on the waste characteristics.

While the dioxins and furans (PCDD/PCDF) are undoubtedly the best researched of the chemicals released from incinerators, they are not the only ones of significance as discussed previously.

In their assessment on gaseous emissions, the EIA report has made assumptions and statements that need to be refuted, these are:

o The EIA report assumes the Worst Case Scenario for gaseous emission to be when The WTE Facility operates under a full load situation with maximum allowable emission concentrations30.

o The EIA report states that for air pollution modelling purposes, the emission concentrations assumed31 the concentrations as stated in the EU Directive 200/76/EC Annex V as reproduced in their Table 4.5b.

o The EIA report states that the emission concentrations of various pollutants are expected to be considerably below the maximum allowable concentrations32

10.3.1 Worst Case Scenario

The worse case scenario certainly does not relate to the maximum allowable emissions concentrations as stated in the EU Directive and adopted by the Promoters.

The worst case scenario will be the emission concentrations that will occur when at full load condition the proposed air flue gas treatment systems are not operational (breakdown, lack of chemicals, etc.).

The report should have computed the concentrations of various pollutants on the basis of the waste characteristics described in the report and reported emission rates for each constituent. This would have constituted the uncontrolled emissions concentrations for the various pollutants and the impacts of these uncontrolled emission concentrations for the various pollutants on the environment assessed. The same assessment should be carried out using controlled emission data (i.e. after air pollution control).

Both SIDEC (1998) and Carl Bro (2005) estimated uncontrolled and controlled emissions rates for the various pollutants and justify the uncontrolled emission rates on the basis of the characteristics of the Municipal Solid Wastes33 and the factors that influence the characteristics. These data are reproduced below.

Table 10.3.1.1: Reported Uncontrolled and Controlled Emission Rates from MSW Incinerator

From the studies of SIDEC and Carl Bro, it is clear that on the basis of the local MSW characteristics and even using the state of the art in pollution control technology, there is strong doubt that the standards of the EU Directive is achievable as postulated in the EIA report . The maximum permissible limits for pollutants are given below.

Carl Bro is even more forceful in their analysis on the controlled emission after flue gas treatment as they concluded that given the likely variation in MSW fuel, in order to meet the EU Directive emission limits, the flue gas treatment will need to be designed to achieve an up to 99.9% capture of particulates, 99.3% capture of HCL and a 93% capture of SO2 38. Thus it is not surprising that Carl Bro concludes that the stringent EU Directive cannot be satisfied under local conditions and instead proposes less stringent emission limits for the various pollutants.

The EIA report mentions that the flue gas treatment system39 for the proposed
WTE Plant consists of:

��� SNCR using aqueous ammonia or urea for NOx removal
��� Dry or semi-dry scrubbing system using hydrated lime for Acid Gas removal;
��� Activated carbon injection for the removal of Volatile metals and Dioxins and Furans;
��� Bag house filters or electrostatic precipitators for Particulate removal

The EIA report provides a review on the removal efficiencies of the state of the art air pollution technology retained for the proposed WTE Plant and states that40:

• For particulate Removal
��� Bag house: 99%
��� ESP: 99%
• For Acids Removal
��� Semi-dry scrubber and dry scrubber: 80-95%

The above analysis brings the following conclusions:

• The types of efficiencies for acid removal in particular as proposed in the EIA
report will not be sufficient to meet the standards of the EU Directive
according to the assessment of Carl Bro.

• The statement in the EIA report that the emission concentrations of various pollutants are expected to be considerably below the maximum allowable concentrations41 must be taken with the uppermost reservations in the light of the studies of SIDEC and Carl Bro in particular. The more so as the EIA report provides neither a detailed assessment of the MSW nor detailed calculations to validate their over the board optimism on the pollutants level in the gaseous emissions.

10.3.2 Emissions Concentrations for Air Pollution Modelling

For the assessment of impacts of gaseous emissions the EIA report assumes that the proposed WTE plant will emit air pollutants at concentrations equivalent to the 24hr average air emission limits of the EU Directive.

In view of the analysis carried out in the previous sections and conclusions we have strong reservations on the above assumption particularly as the EIA report does not provide any scientific data to support their statement.

Furthermore we are convinced that the EU Directive would have specified upper limit concentration for various pollutants taking into consideration the dispersion/non-dispersion aspects and the subsequent impacts of such concentrations on the environment. Simply it means that it is highly unlikely that the maximum concentrations specified would represent a threat to the environment.

In consequence, without even using a dispersion model, one could anticipate that the impacts on the environment would have been virtually nil or minimal at the pollutants concentrations specified in the EU Directive. The scenario could be different if other sources of gaseous emissions were present in the near vicinity and contribution to the baseline air quality needs to be taken into account. However the dispersion model used cannot predict the cumulative air quality form various sources.

The EIA Report seems to indicate that the maximum limits set out in the EU Directives are stringent enough whereas Clause 13 of the said Directive clearly spells out that “Compliance with the emission limit laid down by this Directive should be regarded as a necessary but not sufficient condition for compliance42 with the requirements of Directive 96/61/EC. The Directive further states that “such compliance may involve more stringent emissions limit values for the pollutants envisaged by this Directive, emission limit values for other substances and other media, and other appropriate conditions”.

Finally it must be said that the emissions during start up, shut down and upset conditions when the greatest emissions are expected to occur whereas emissions
are generally measured under steady state conditions.

10.3.3 Impacts on Sensitive Ecological Areas such as
Corps de Garde Mountain

Although the EIA report recognises that the native rich Corps de Garde Nature Reserve is a few hundred metres to the south east of the study area (p8-13), yet it is not identified as an air sensitive receiver for gaseous emissions impact assessment.

Corps de Garde Mountain Nature Reserve is protected under the Forestry and Nature Reserves Act and covers 90.33 ha of the mountain.

Although highly degraded by introduced plant species, and at risk to fire, the cliffs and summit of Corps de Garde mountain provide an important refuge for the highly endangered plant biodiversity of Mauritius.

Plant biodiversity43:

The vegetation of Corps de Garde comprises an unusual mixture of species from the drier forests of the west, and species from moister mountain ridges. There are almost100 native plant species. Many of the species found on the mountain are threatened (such as the critically endangered Hibiscus fragilis and Syzygium guehoi), and some critically endangered endemic species are only found on Corps de Garde, these include:

• Trochetia parviflora (thought extinct, until rediscovered in 2001) – less than 30 adults on the SW flank;
• Barleria observatrix - less than 30 plants found on the NE cliffs of the mountain;
• Psiadia trilobata (through extinct, until rediscovered in 2005) – a small population in the same location as the Trochetia.

Active management: 1 hectare of the mountain is under active management to provide a habitat free of introduced species for the Trochetia parviflora and Psiadia trilobata, two endemics thought extinct until rediscovered in 2001 and 2005 respectively.

The impacts on Mountain St Pierre should also have been assessed.

Thus it can be concluded that the EIA report has failed to demonstrate that the gaseous emissions (controlled or uncontrolled) has not impacts whatsoever on the environment and that the well being of the population is not at risks.

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29 EIA report p3-3
30Bold and underline not from the text of the EIA report and presumably the EIA report is assuming the values of maximum concentrations of pollutants as stated in the EU Directive (p4-10).
31 Bold and underline not in the text of the EIA report (p4-14)
32 Bold and underline not in the text of the EIA report (p4-10 1st paragraph – Modelling scenario)
33 For Carl Bro the fuel feed to the incinerator consists of MSW only whereas in the study of Sidec, the fuel feed to the incinerator consist of a mixture of MSW, bagasse and charcoal
34 Carl Bro reports concentration of pollutants as a function of ash content of MSW. The lower values correspond to an ash content of 10% and the higher value of the range to an ash content of 20%.. Carl Bro further assumes that there is no removal of pollutants by the combustion ash but in practice removal takes place.
35 Without De Nox
36 Without De Nox
37 Annex V of EU Directive (2000/76/EC)- Please refer to the annex for the details such as sampling periods and others.
38 Carl Bro Report. Section 5.4.4
39 EIA report: Section 3.7.4 p3-19
40 EIA report: section 3.7.2 p3-17.
41 EIA report: p-4-10. Bold and underline not from the EIA report
42 Bold and underline for emphasis.
43 Personal Communication: Rachel Atkinson, Biologist.

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