Introduction

The rapid strides of economic development, particularly in urban areas, need intensive use of natural resources, that affects the environment leading to ecological problems.

The compilation of environmental baseline data is essential to assess the impact on environment due to the project activities. The environment includes water, land, air, ecology, noise, socio-economic issues etc.

General Environment

The average elevation of Delhi plains is around 198-200m above MSL. River Yamuna flows across the eastern flank of the city. Many small water courses intersect the terrain, causing a variation in relief. However, average gradient of terrain is gentle, of the order of 1 to 3m/km. The area has mature topography with isolated hillocks.

Water and Soil

The water and soil samples had been tested for chemical analysis. Total dissolved solids, and flouride in the water sample are on higher side and need treatment if used for drinking. Most of the other parameters are within the permissible limits.

Composition of soil shows predominance of sand over silt and clay. PH of the soil sample indicates that soil is alkaline in nature. Based on this data, it could be concluded that sub-soil and underground water are unlikely to undergo any deteriorating effect due to proposed Metro structures and foundation

Flora of the Project Area

Tree survey was carried out along the proposed alignment. Trees are to be cut on the land where the stations are proposed and on the land that will be permanently acquired at station locations. The main species along the alignment are Pipal, Neem, Kikar, Eucalyptus, Ashok, Ficus and Bakaan, etc. No rare or endangered species of trees had been noticed during field studies. About 14 trees exist on the proposed alignment.

Air Quality

As a part of this study, ambient air quality monitoring (AAQM) had been carried out by setting up ambient air quality monitoring station at Dwarka area for the parameters SPM, CO, SO2, and NOx. The ambient air quality data indicates much higher value of suspended particulate matter than the prescribed limits established by CPCB at the monitoring station. However, the values of SO2, NOx and CO are within the permissible limits.

Seismicity & Noise Levels

Noise levels were measured at Dwarka area at 2.0 m away from source as per standard practice. It could be concluded that the noise levels recorded are higher than the prescribed permissible levels of 65dBA (day) and 55dBA (night). Since the project area falls in Zone IV of Seismic Zoning Map of India, this necessitates the need to be considered for design purpose for civil engineering structures and while finishing civil designs.

Positive Environmental ImpactsPositive environmental impacts identified and discussed are (a) traffic congestion reduction, (b) quick service and safety, (c) less fuel consumption, (d) reduction in air pollution, (e) better roads, and (f) employment opportunities.
Negative Environmental Impact)

1) Impacts Due to Project Location

i) Change of land use: The alignment changes from underground to elevated section. For different components of this corridor 3375 sqm of DDA land shall be acquired. The cost of land is already incorporated in the project.

ii) Loss of trees: Due to the proposed Metro construction, approximately 14 trees are likely to be lost. The total value of these trees is Rs 9800. As per the Department of Forests stipulations, about 140 plants are required to be planted; their total cost works out to be Rs 31000.

2) Impacts Due to Project Construction

i) Soil Erosion and Health Risk at Construction Site:

a) Run off from unprotected excavated areas, and underground tunnel faces can result in excessive soil erosion, especially when the erodability of soil is high. Mitigation measures include careful planning, timing of cut and fill operations and revegetation. In general, construction works are stopped during monsoon season.

b) Problems could arise from dumping of construction spoils. It is proposed to have readymade mix at site directly from batching plant for use at site; materials like steel etc will be housed in a fenced area.

c) Health risks include disease hazards due to lack of sanitation facilities. Mitigation measures include proper water supply, sanitation, drainage, healthcare and human waste disposal facilities.

d) Traffic diversions and risk to existing buildings during construction: Minimum traffic diversions on roads will be required as the stretch is very small, as the grade and elevated section is mostly on barren land. In underground portion, the building line is considerably away from the proposed cut and cover and tunnels. Hence, no risk is foreseen to adjacent buildings.

e) Impact on water quality: Construction activities may have an adverse impact on water bodies due to disposal of waste. The waste could be due to the spillage of construction materials. Contamination of ground water can take place, if the dump containing above substances gets leached and percolates into the groundwater table. This is not the case with the present project, as the activity does not involve usage of any harmful ingredients.

f) Disposal of soil during construction of underground Metro projects is a specialized and complex task. Owing to paucity of space in the busy cities and for safety reasons, surplus earth would have to be transported to the nearby site of DMRC requiring earth filling. During construction, about 8476 m3 of soil is likely to be excavated. Out of this, 848m3 (10%) is likely to be reutilized in filling. The balance 7628m3 (90%) will be disposed of.

3) Impacts Due to Project Operation

i) Oil Pollution: Oil spillage during change of lubricants, cleaning and repair processes, in the maintenance of rolling stock, is very common. The spilled oil should be trapped in grit chamber for settling of suspended matter. The collected oil should either be auctioned or incinerated, so as to avoid any underground water contamination.

ii) Noise: The main sources of noise from the operation of trains include: engine noise, cooling fan noise, wheel rail interaction, electric generator and miscellaneous noises like passenger’s chatting. The operation of metro will however reduce the noise level by about 7-9%.

iii) Accidental Hazards: In view of the hazards potential involved due to failure of system and accident, the onsite and off site emergency measures have been formulated and will be implemented.

iv) Metro Station’s Water Supply and Refuse: Public Health facilities, such as water supply, sanitation and toilets are very much needed at the stations. An amount of 45 litres per day water supply to persons working at stations has been recommended by CPHEEO. As also water for fire emergency is required. This works out to about 1,30,000 litres/day. Also the refuse will be very little to the tune of 3g/day/person. Both these have already been considered in CP - Dwarka section and New Delhi-IGI airport section. respectively.

v) Visual Impact: The construction of the above corridor will bring about a change in visual look of the streets through which it will operate. An architecturally well designed structure, could be aesthetically pleasing and able to reduce impact due to visual disfiguration.

vi) Vibration Control: Vibration emanates from rail wheel B interaction and the same can be reduced by minimizing surface irregularities of wheels and rail, improving track geometry, providing elastic fastenings, and separation of rail seat assembly from the concrete plinth with insertion of resilient and shock absorbing pad.

Environmental Management System

The Environmental Management System constitutes provision of an Environmental Division, which should be staffed by an Environmental Engineer/Officer, an Environmental Assistant and two other assistants (miscellaneous works). The task assigned should include supervision and coordination of studies, monitoring and implementation of environmental mitigation measures. An Environmental Adviser shall review progress of the division every year. Cost of such an establishment is attributable to another system of the entire metro. The Environment Management Plan should be implemented in phases, so that optimum benefit could be achieved and it should be synchronized with the construction schedules.