Environmental impact assessment for the proposed multi-storey building at H. Blue Haven Malé City, Maldives

Abstract

This report discusses the findings of an Environmental Impact Assessment (EIA) carried out for the proposed 13-storey building at H. Blue Haven, Malé. The project is proposed by the Ministry of Housing and Infrastructure. EIA is required for buildings with basements or foundations that are laid below 1.8m from the ground, as per the EIA Regulations of the Maldives and all amendments to it up to date. The main objective of the EIA is to identify potential impacts of excavation, construction of foundation and dewatering and consider mitigation measures that may be adopted. In addition, the EIA would also consider other construction phase and operational phase activities such as waste management, energy and water supply although they are not directly related to the scope of the EIA. Demolition of the existing single storey building has been completed, and demolition impacts have not been covered in the EIA in detail. The project is to commence as soon as the EIA is approved and the duration of the project is estimated to be 716 days with the project completion targeted to end of Feb 2018. Substructure works, which is considered to be the most sensitive component (socially and environmentally), is expected to be completed within two months. The critical elements of excavation and dewatering are expected to be completed within 80 days. Therefore, the project has a critical impact timeframe of less than 4 months. Environmental assessment for building construction in Malé City was enforced following incidents of cracks in neighbouring buildings and vibration and noise-related inconveniences which occurred when deep piling was undertaken for the construction of the 15-storey building in Athireege-aage. Based on this incident, deep piling is considered unsuitable for the congested Malé. Therefore, the most commonly adopted method of raft foundation will be adopted in the construction of the proposed multi-storey building at H. Blue Haven. This method distributes the load from a structure over a large area, minimizing the pressure on the base. This method of foundation is ideal for loose soils with low bearing capacity. However, since the soil of Malé with well-compacted heterogeneous material provides very good base for such foundations, there would be minimal disruption to adjoining structures. It is believed that Blue Haven is on the original natural land of Malé, however even if it were on reclaimed land, the foundation will be the on the original seabed and naturally compact conditions would prevail. The proposed depth of the foundation for H. Blue Haven is at 2.65m below the existing ground level or road level. This depth is not considered to have major adverse impacts due to excavation given that the soil has good bearing capacity. The main concern in excavating to this depth is the safety of the adjacent structures. However, there are no structures adjoining the proposed building or plot and roads surround the entire plot. Furthermore, adequate space is left between the proposed building and the roadside providing a wide walkway. Therefore, there may not be a need for foundation protection for adjacent buildings. Nonetheless, foundation protection would be provided as required and care will be taken during excavation and dewatering, especially during rainy season. For dewatering, there are two options: (1) Malé Water and Sewerage Company (MWSC) installs a purpose built catchpit connecting to the main sewerage network and the Contractor pumps effluent from the dewatering process into this catchpit using multiple pumps at designated locations, or (2) Maldives Roads Corporation (MRDC) lays a pipeline to the harbour or sea through which the dewatering effluent is pumped to sea. In the latter case, the effluent discharge to sea can be easily visible if discharged into the harbour but may not be so if discharged to sea off the harbour. Therefore, if this option were to be chosen, the discharge shall be off the harbour into the sea. Since dewatering is required throughout the process of laying the foundation, it will be continuous and irrespective of tide. In fact, tidal influence on the groundwater table has been seen to be very little or negligible in most of the larger islands. General construction machinery including a small excavator, hydraulic crane, lorry, fork lift, dump truck, and backhoe loader would be used in addition to concrete machines and other tools and machinery. Excavator, lorry and backhoe loader would be used mainly during the excavation stage while the hydraulic crane would be used for laying concrete works on the top floors. In Malé, this is carried out during the night to minimize disturbance to day time activities and traffic flow. However, there would be some degree of noise disturbance to neighbouring residential buildings, which would be less given that most of the buildings in the vicinity are for institutional use. During excavation, excavators and lorries will work inside Blue Haven plot except for some minor works on the roadside. Soil that is excavated is expected to be mainly fine sand free from debris and soil would be segregated and debris and contaminants removed for use in backfilling. Demolition has been completed quite some time ago. The plot has been vacant for quite some time. Demolition is not within the scope of this EIA. Cement dust during concrete works is expected to be less of an issue compared to demolition dust and dust during sanding of walls. All these dust-prone activities are expected to be carried out with caution to minimize dust levels in the area. During concrete works, concrete machine and mobile telescopic crane will work from the road and appropriate road blocks, safety and traffic diversion measures will be implemented according to the requirements/recommendations of Ministry of Housing and Infrastructure/Malé City Council and Traffic Police. Safety measures within and outside the premises will be ensured during demolition of existing building until the end of construction phase. The project plot is one entire block and does not have any other buildings in the block. On the west is Sosun Magu, which is a wide road and another wide road on the north (Ameer Ahmed Magu) and two narrow roads namely Roashanee Magu and Roashanee Hingun on the south and east respectively. The block on the east of the plot followed by Roashanee Hingun is the most congested block with a complex array of single and multi-storey buildings. Similar congestion occurs on all sides although there is a mosque on the north and a school opposite the northwest. Previously, the Blue Haven plot was a recreational center for government emplyees named as Sarukaaru Muvazzafunge Naadhee and the place is often referred to as Naadhee. There was a two storey building and large open space for badmington and other outdoor sports activities. There are several large trees, which have been kept when the building was demolished and plot cleared in preparation for the proposed building. Due to the congested nature of Malé and the area surrounding the project site, the condition of neighbouring houses was considered including condition of the structures, condition of groundwater (if groundwater is used) and living conditions to some extent. It has been identified that most of the buildings are old, single-storey or two-storey buildings and have several cracks due to ageing and settlement (mainly on the ground floor in high rise buildings) but could not have been subjected to vibration impacts in the past. There is no structural damage in the existing multi-storey buildings. Traffic in the area was considered important and was assessed to be similar to other areas of Malé. Traffic and pedestrian numbers increases in the evening after 1600hrs because people are usually out during the evening to cool off. Furthermore, traffic is also a concern in the areas due to the institutional nature including Majeedhiyya School, the mosque and the Maldives Islamic Bank Head Office opposite the northeast corner. The two main road on the north and west are two-way roads while those on the south and east are one-way roads. The one-way roads may make traffic diversions during the construction phase easier. All parking spaces are nearly full throughout the day mostly with parked motor cycles. Private cars are becoming increasingly common in Malé today, therefore, getting parking space on the road is also becoming increasingly difficult. In terms of living conditions in the vicinity of the project site, most of the houses have congested living conditions except for some multistorey buildings. Groundwater is still quite commonly used in households for washing, flushing and other non-potable uses. Noise levels in the area are much higher than expected and average noise levels during day time as well as night time surpasses acceptable international standards for residential areas. There are also noise sources in the vicinity such as the busy harbour which add to the background noise levels of the area. While the project is primarily targeted at middle to high income category housing needs, the primary objective of the development is to meet the housing needs of an ever-increasing population of Malé, provide adequate and affordable housing and to improve living conditions in Malé. The living environment in Malé is in grave condition with building after building without any space except public spaces and roads. Most of the single storey houses and some of the multi-storey buildings have congested living spaces. With a population density of 18,000persons/square kilometer of land area, and thousands of vehicles, Malé needs vertical growth and with increasing land value multi-storey buildings with adequate parking spaces in the building is an important aspect of development in Malé. Furthermore, the project also aims to meet election pledges as well as to provide luxury apartments to meet the growing demand for luxury apartments. The overall environmental and social impacts of the projects have been assessed and impacts are considered to be low magnitude and of minor significance. The negative environmental and social impacts of the development are also mainly short-term while the positive socioeconomic impacts of the project are long-term. Therefore, the overall impact of the proposed projects is greatly positive resulting mainly from improved living spaces and economic benefits, both direct and indirect. There would also be direct and indirect employment opportunities in the planning/design phase, construction phase as well as operational phase of the project. The socio-economic benefits of the project can be considered to outweigh the negative impacts of the project. The main potential impact of building projects in Malé would be possible damage to neighbouring structures due to vibration and weakness to substructure caused by soil movement due to deep excavation and dewatering. However, in this project, these impacts are negligible since the building footprint and subsequent excavation area is at a considerable distance from the road and especially any structures in the vicinity. Disturbances to neighbours is an inevitable impact that will have to be minimized by taking appropriate measures to minimize nuisances such as noise and controlling dust and taking safety precautions. The construction staff needs to know about the importance of minimizing noise and dust and neighbours shall be made aware of the nature of works and potential disturbances. A grievance redress mechanism would have to be in place and made known to neighbours. Such a mechanism has been proposed in the report. Impacts due to dewatering is not expected to be felt on adjacent buildings since the buildings are at a considerable distance and vertical movement in soil would be small during excavation. Impacts of excavation and dewatering include loosening of subsoil and reduction in bearing capacity of the soil. This would generally occur in loose soil but not in compact sandy soil, as found in the project site, which is considered to be part of the original island of Malé. Sand particles have irregular shapes and sizes, therefore, it is well locked in place giving it a good load bearing capacity. Since the excavation is not too deep (less than 3m from the ground surface), excavation would not have major impacts on the adjoining structures/buildings. The drawdown caused by dewatering on the water table is not expected to cause any loosening of subsoil in the area, since dewatering occurs at a shallow depth from the water table. However, there may be an impact on neighbouring wells. The superficial groundwater lens will become saline due to drawdown. The current practice of using several small pumps instead of small number of large pumps minimizes such drawdown and there would be minimal impact on neighbours’ use of groundwater. However, this has to be monitored for the adjoining wells and provisions made to compensate for any drawdown effects. There are a few freshwater dependent trees in the area, which are at a distance from the project and would not be adversely affected due to salinization of the water lens. Yet, appropriate mitigation of the impact by watering the trees including salt tolerant trees such as Burmese rosewood (ofi eley) trees and banyan tree in the project site regularly during the course of the dewatering works has been recommended. Atmospheric pollution due to concrete mixing works on site, cutting tiles, grinding and sanding of walls and timber works are of concern. Often only interior walls undergo smoothing by sanding and this process occurs within confined space. Carpentry works on site would be limited. Yet, it is often the case in Malé that interior finishing works are undertaken at night and with current regulations allowing noisy operations until midnight, there are certain disturbances that has to be minimized, especially given that the project happens in a mixed residential area. Other mitigation measures for the proposed project would be to design for maximum natural ventilation and light, design for optimal efficiency of building while minimizing on losses such as excess concrete as in some of the recent buildings, minimizing and taking care in dusty operations, taking heed of noise during school hours and prayer times as well as night time and keeping the work areas safe and clean. The overall impacts of the proposed project are largely positive with some minor negative impacts. Yet, environmental monitoring has been proposed in order to ensure the effectiveness of the proposed impact management and mitigation measures. The proposed monitoring programme considers engineering inspection during foundation works, groundwater quality changes and availability during dewatering (if necessary), dust and noise during construction, complaints/grievances, waste management measures including management of excavated sand, and provision of personal protective equipment as well as incidents/accidents at site. In conclusion, it appears justified from a socio-economic and environmental point of view, to carry out the proposed project.