Sunday Times 2
Port City: Good site practice minimises particle pollution
We refer to the above article published in the Sunday Times of 19th November 2017, by Ms Carmel Corea, and draw your attention to the writer’s statement where she says, “No mention is made of the effect of the ambient toxic particulate matter PM10 and PM2.5 that would be produced during the 15-20 year project period”
At this point in time, the effect of these particles are purely academic where Port City is concerned because the current readings are within safety limits. However, we would like to point out that both the SEIA (Dec, 2015) and EIA (Oct, 2017) discuss the particulate matters under the relevant chapters on air quality. In particular, EIA (Oct, 2017), provides records on PM10 and PM2.5, which still comply with safety standards.
To quote from EIA, OCT 2017 Chapter 4, page 10: “According to Ambient Air Quality Standards stipulated by the Ministry of Environmental and Natural Resources of Sri Lanka, under the Extraordinary Gazette, No. 1562/22, August, 15, 2008, the Concentration of PM10 and PM2.5 over an average period of 24 hours, can only be at a maximum of 100(μg/m3) and 50 (μg/m3) respectively. While Ambient air quality measurements were done in the years 2014, 2015 and 2017 for 6 locations in the port city area, the concentrations of PM10 and PM2.5 always remained much less than the respective maximum permissible level.”
In general, air pollutants including particulate matters dispersion in the atmosphere from point, line, and area sources are mainly dependent upon the prevailing micrometeorological character of a region. Wind is an important factor which determines the dilution and dispersion of the pollutants. Since Colombo is situated on a flat terrain close to the sea, it helps disperse pollution over a larger area and this fact is well established in a number of scientific researches.
Many refer to the monitoring programme conducted by the CEA in proximity to the Colombo Fort Railway Station and conclude that the level of particulate matters (PM10) in Colombo City is higher compared to WHO guidelines and CEA standards for which the maximum permissible level is 50μg/m3. However, as described in the EIA of October 2017 (mentioned above), the air quality measurements conducted over the last 5 years at locations around the coastal area in Colombo City (particularly near the Port City project area) where dispersion can be expected, show that the concentrations of PM10 and PM2.5 always comply with the CEA standards.
During the construction phase of the Port City Project, air quality impacts including particulate matters will be minimized by adopting practical mitigation measures as proposed in the EIA, OCT 2017. Most of these measures just reflect good site practice, and will be the general norm for experienced contractors.
Principles and concepts on urban ventilation which will be directly linked with dispersion of air pollutants such as PM10 and PM2.5 are incorporated in the Port City Master Plan at city level, block and building level.
These concepts include orientation of urban grids, breezeway, non-building areas, waterfront sites, building heights and obstructions, which were studied, adapted and applied to the Port City project Master Plan. All these aspects are discussed in details in EIA, Oct 2017.
No industrial activities will be allowed within Port City. Therefore, the expected source for air pollution including particulate matters will be vehicular emissions. The identified main sources are; (a) increment in external traffic flow, especially in A2 road and (b) Lotus Road and additional internal traffic flow in internal transport network of the Colombo Port City. PM10 is mainly emitted from diesel powered vehicles, which constitutes light duty vehicles, buses etc.
We also wish to point out that the proposed Port City will have around 45 ha or 110 acres of public parks (an area 8 times larger than the 5.7 ha available at Galle Face Green.) and 125 ha or 300 acres for public use for recreation and water sports. Despite the initial impact on air quality during the construction phase, Port City will have street trees, courtyards and green roofs. Even the height of buildings are required to strategically decrease towards the direction of prevailing winds or water fronts for increased air circulation within the city.
As per the numerous statements made by Port City in the past, sand dredging is carried out in a completely sustainable manner at distances of over 7.5km from the shoreline, and at depths of 15m or more. The dredging has no impact on coastal erosion or livelihoods and the depth of dredging is limited to 3m from the surface of the seabed, and a thickness of sediment of at least 0.5m is maintained. It is a scientifically proven fact any qualified coastal engineer will confirm that any dredging beyond the dynamic coastal zone of around 2km from the shoreline and more than 8m in depth has no impact on coastal erosion. Port City was imposed limits of more than double this minimum standard. Also, all offshore sand mining sites used for dredging will comply with environmental regulations.
Also, the total quantity of rock material required for the development of marine structures has been estimated as 3.45 million m3. The total quantity of rock material that could be mined from the 11 quarries studied (out of 127 quarries in IML A,B and C category located in Gampaha, Colombo and Kalutara Districts) alone is 6.45 million m3 (information on the quarrying sites is given in table 2.12 page 41 of chapter 2 of the Dec 2015 SEIA.) Therefore, the needed amount of rock material is only about 44% of the total mineable quantity of these 11 quarries.
To study the percentage of national requirements, impacts on the country’s construction industry and the expected impacts due to demand for quarry materials for the construction of marine protection structures, a comparison of existing quarries, IML (A, B & C) category quarry details of Colombo, Kalutara and Gampaha Districts were obtained from the Geological Survey and Mines Bureau (GSMB). According to findings presented in section 4.3.5.of the SEIA, Dec 2015, (Refer: Table 4.21 – Details of Existing Quarries in Colombo, Gampaha and Kalutara Districts), only 7.0%, 2.3% of the quarry capacities of the quarries in Colombo and Gampaha respectively, is required to supply the total quarry material requirement of the project. Hence, the impact of this project on the national quarry material requirement would be in negligible proportion according to the GSMB-Technical Services findings presented in SEIA Dec 2015 Section 2.3.3.
The cumulative quarry rock requirement to build-up 5.6 million sq. m of building space over a 23 – year period is 1.7 million m3 (Note that for the ongoing reclamation works, under the approved SEIA Dec 2015, the quarry rock requirement is double this quantity or 3.5 million m3 to be used over a 3-4 year period. EIA, October 2017 Section 3.1.1). The annual quarry material requirement for the building construction of the Port City project; 0.075 million m3, is a trivial amount of the total quarry production in Western Province.
Bathymetry of the reclamation site and dredging sites of the proposed project are given in the SEIA, Dec 2015 (Chapter 3 section 3.1.1 and section 3.1.2). Coastal hydrodynamic pattern and the marine sensitiveness of the area were studied together with the sediment thickness (dredgable sand thickness) of the mining area. It should be noted that only 42% of the area was recommended by the SEIAs out of the three mining sites considered initially to provide the freedom for fisherman to do their fishing activities. Later on the request from the fishermen, dredging was further limited to the offshore area of site 2 (beyond the 7.5km from the shore), which lead to further reduction of dredgable area. Currently the approved dredging area is limited to the 50km2 and it is about 27% of the total studied area under the EIAs.
The dynamic coastal zone is limited to near shore area and all the coastal processes are happening within that region. Dredging is taking place in deep water, where the depth is more than 23m and the approved total dredging area is more than 50km2. To meet the total requirement of 65 million m3 of sand over the approved area, required dredging depth would be 1.3m. Change of morphology about 1.3m in deep water will not alter the wave patterns in the area. Wave conditions vary considerably from site to site, depending mainly on the wind climate of the area. Alteration of wave direction is only possible close to the proposed port city development area due to the reclamation and its associated structures but not possible in the dredging area as mentioned in the article. Therefore, it is possible to change the wave climate periodically with the influence of monsoonal winds, but not due to the small depth variation in the deep sea as mentioned in the article.
Hydrodynamic pattern in the area was studied in detail both during the planning and designing stages of the project and most appropriate orientation is proposed for the development with minimizing impacts to the surrounding environment.
Sediment transport from the south will be interrupted by the southern arm of the breakwater of the Colombo South Port, which will act as a groyne. Sediment by pass to the north will be minimum and it could be a cause of less sediment balance in the north. The proposed port city development and introduction of the curved offshore breakwater around it facilitate the sediment bypass to the north. This will create a positive impact on beach erosion which could be possible due to the south port breakwater alone.
After construction of the Port City, the wave condition north of the project site, including the Colombo South Port, is not expected to be affected.
Nihal Fernando
Project Director / Colombo Port City
Ministry of Megapolis & Western Development