5 anticipated environmental impacts and mitigation measures

138 Pages·2012·5.38 MB·English

EIA/EMP AND RA/DMP FOR DRILLING
OIL AND NATURAL GAS CORPORATION OPERATION OF EXPLORATORY WELLS IN ANTICIPATED ENVIRONMENTAL IMPACTS
LIMITED 30 BLOCKS AND MITIGATION MEASURES

5 ANTICIPATED ENVIRONMENTAL IMPACTS AND
MITIGATION MEASURES
5.1 Introduction
In this chapter, we:
 Identify project activities that could beneficially or adversely impact the environment
 Predict and assess the environmental impacts of the such activities
 Examine each environmental aspect-impact relationship in detail and identify its degree of
significance
 Identify possible mitigation measures for these project activities and select the most
appropriate mitigation measure, based on the reduction in significance achieved and
practicality in implementation
5.2 Impact Assessment Methodology
5.2.1 Key Definitions
Environmental Aspects
These are elements of an organization’s activities or products or services that can interact with the
environment. Environmental aspects could include activities that occur during normal, abnormal and
emergency operations.
Environmental aspects selected for further study should large enough for meaningful examination and
small enough to be easily understood.
Environmental Impacts
Environmental impacts are defined as any change to the environment, whether adverse or beneficial,
wholly or partially resulting from an organization’s environmental aspects.
Environmental Indices
The environment includes surroundings in which an organization operates such as air, water, land,
natural resources, flora, fauna, humans and their interrelation.
The environmental indices (or parts of the receiving environment on which impacts are being
assessed) include: Land use/land cover, air quality, noise quality, surface water environment, ground
water environment, soil, ecology and bio diversity, socio economics, occupational health, community
health and safety
After the identification of impacting activities, impacts require to be assessed based on subjective /
objective criteria to assess the impacting activities. This is done in the following steps.
5.2.2 Identification of Impacts
This entails employing a simple checklist method requiring:
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1. Listing of environmental aspects (i.e. activities or parts thereof that can cause environmental
impacts)
2. Identifying applicable components of the environment on which the environmental aspects
can cause an environmental impact
3. Making notes of the reason / possible inter-relationships that lead to environmental impact
creation
4. Listing the environmental components likely to receive impacts, along with the key impacting
activities on each component
5.2.3 Component Wise Environment Risk Assessment and Mitigation
A component wise approach to environmental risk assessment and mitigation is now applied. For each
environmental component this is carried through a series of steps as follows.
Step 1: Review and Assessment of the Specific Aspects Generating Environmental Risk
Several scientific techniques and methodologies are also used to predict impacts on the environment.
Mathematical models are useful tools (where applicable) to quantitatively describe the cause and
effect relationships between sources of pollution and different components of environment. In cases
where it is not possible to identify and validate a model for a particular situation, predictions have
been arrived at based on logical reasoning / consultation / extrapolation or overlay methods. In any
case, for each component of the environment, the methods used to arrive at the likely impacts require
to be described.
Step 2: Quantifying the Environmental Risk, Identifying Aspects Causing Unacceptable
Levels of Risk and Prioritizing Aspects Requiring Mitigation Measures
Once a general understanding of the impacts has been studied and understood, efforts are made to
compare different impacts so as to prioritize mitigation measures, focusing on those impacting
activities (i.e. aspects) that require urgent mitigation. For ease of comparision across different
activities, a summary environmental risk score is calculated. Two key elements are taken into
consideration based on standard environmental risk assessment methodologies:
 Severity / consequence: the resultant effect of an activity and its interaction with the physical,
biological and/or socio-economic environments
 Probability: the likelihood that an impact may occur due to the project activity/aspect
A combination of severity / consequence with probability gives a reasonable measure of environmental
risk, which aids in decision making. It must always be kept in mind that any scoring methodology
howsoever well defined is subjective and different persons can arrive at different impact risk scores
based on their understanding / opinion. Therefore end results should be evaluated against past
experience as well as professional judgment as well as project and activity specific conditions to
ensure adequacy and equity. Kadam has made an effort to ensure that the scoring does not change
significantly assuming that different evaluators are equally well informed on the project as well as
knowledgeable on the concerned issues. The steps in identifying environmental risk follow.
1. Scoring the Impact Severity / Consequence
The consequences on various environmental receptors have been ranked into 5 levels ranging from
insignificant to catastrophic consequence and are given in Table 5-1.
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Table 5-1: Impact Scoring System – Consequence Assessment
Impact and Score10
Environmental
S. Insignificant Major Catastrophic
Component Minor Consequence Moderate Consequence
No. Consequence Consequence Consequence
Impacted
(+/-) 2 points (+/-) 3 points
(+/-) 1 point (+/-) 4 points (+/-) 5 points
C1 C2 C3 C4 C5 C6 C7
Very short term (< 3 Short term (3 months – 1
Medium term (1 - 3 years) Long term (>3 years) Permanent and irreversible
Landuse / months) and reversible year) and reversible change
1 and reversible change in irreversible change in adverse change in landuse
Landcover change in landuse and / or in landuse and / or
landuse and / or landcover landuse and / or landcover and / or landcover
landcover landcover
Moderate environmental Unacceptable
Minor environmental impact Significant environmental
Temporary nuisance due to impact due to controlled / environmental impact due
due to controlled / impact due to release of air
controlled / uncontrolled uncontrolled release of air to release of air emissions,
uncontrolled release of air emissions, odor / dust or
2 Air Quality release of air emissions, emissions, odor / dust or odor / dust leading to
emissions, odor / dust or greenhouse gases leading
odor / dust or greenhouse greenhouse gases leading possibility of chronic / acute
greenhouse gases with no to exceedance of limits
gases to visual impacts, at health issues, injuries or
lasting detrimental effects specified in EP Rules’
significant nuisance levels fatalities
Background Noise Levels, with respect to Applicable Limit11 as per The Noise Pollution (Regulation and Control) Rules, 2000, as
Ambient Noise - Measured at Boundary of Relevant Noise Generating Unit
give the mean <10% or more Between <10 to <5% Between <5% or the limit Upto 5% above the limit >5% above the limit
score from the
Incremental Noise Levels, as Predicted at Boundary of Relevant Noise Generating Unit
3 three
1 dB(A) or less 1 dB(A) – 2 dB(A) 2 dB(A) – 3 dB(A) 3 dB(A) – 4 dB(A) 4 dB(A) or more
categories,
rounded to the Incremental Noise Levels, as Predicted at Boundary of Nearest Human Settlement / Sensitive Receptor from Boundary of Relevant
nearest decimal Noise Generating Unit
0.5 dB(A) or less 0.5 dB(A) – 1 dB(A) 1 dB(A) – 1.5 dB(A) 1.5 dB(A) – 2 dB(A) 2 dB(A) or more
1

10 In case none of the impacts are applicable, then Not Applicable (NA) is written in the appropriate cell.
11 For leq (day) or leq (night), whichever is higher.
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Impact and Score10
Environmental
S. Insignificant Major Catastrophic
Component Minor Consequence Moderate Consequence
No. Consequence Consequence Consequence
Impacted
(+/-) 2 points (+/-) 3 points
(+/-) 1 point (+/-) 4 points (+/-) 5 points
C1 C2 C3 C4 C5 C6 C7
Water Consumption (KL/D)
Surface Water - < 50 51 – 100 101 - 250 250 – 500 501 and more
give the mean
Water Consumption, Duration
score from the
4 three < 1 year 1 – 3 years 3 – 5 years 5 – 10 years 10 years or more
categories, Wastewater Discharge Quality
rounded to the Other discharge within Other discharge, outside
Discharge to an authorized,
nearest decimal No wastewater generation Zero Discharge12 limits specified by the EP limits specified by the EP
functional CETP
Rules Rules
Location of Drawl, as per CGWA / CGWB Regulations
Safe Semi-critical Critical Over-exploited Notified
Ground Water -
Water Drawl (KL/D)
give the mean
< 50 51 – 100 101 - 250 250 – 500 501 and more
score from the
Water Drawl, Duration
5 three
categories, < 1 year 1 – 3 years 3 – 5 years 5 – 10 years 10 years or more
rounded to the Wastewater Discharge Quality
nearest decimal
Other discharge within Other discharge, outside
Discharge to an authorized,
No wastewater generation Zero Discharge limits specified by the EP limits specified by the EP
functional CETP
Rules Rules
1

12 Meaning that any wastewater generated is recycled and any non-recycled water is disposed without discharge, through an appropriate means such as thermal destruction.
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Impact and Score10
Environmental
S. Insignificant Major Catastrophic
Component Minor Consequence Moderate Consequence
No. Consequence Consequence Consequence
Impacted
(+/-) 2 points (+/-) 3 points
(+/-) 1 point (+/-) 4 points (+/-) 5 points
C1 C2 C3 C4 C5 C6 C7
Loss of upto 80% topsoil, Loss of upto 100% topsoil,
Loss of upto 20% topsoil,
Loss of upto 40% topsoil, Loss of upto 60% topsoil, or actual or possible or actual or possible
or minor contamination of
or actual or possible or actual or possible contamination of soil contamination of soil
soil that can be easily
6 Soil Quality contamination of soil contamination of soil volume >25 m3 and above volume >25 m3 and above
restored close to original
volume <25 m3 but below volume <25 m3 but above Dutch Intervention Values, Dutch Intervention
condition for volume <10
Dutch Intervention Values Dutch Intervention Values but not deemed to require Values13, and deemed to
m3
urgent remediation require urgent remediation
Significant changes in flora/
fauna population and
habitat. Disruption to, or
some death of rare flora
Long term and significant
Minor impact on flora/fauna and fauna, but not resulting
Continuous and serious change in population or
and habitats, but no in eradication of
Insignificant Environmental damage by erosion or to habitat with negative
negative impacts on endangered species. Non
Ecology and Impact. Occasional damage flora or fauna. Major impact on ecosystem
ecosystem function. Limited persistent but possibly
7.1 Bio-diversity: by erosion, or of flora and disruption to or frequent function. Widespread
damage to minimal area of widespread damage to
Terrestrial fauna. Some disturbance to death of rare flora or fauna. destruction to a significant
land. Temporary damage land, damage that can be
flora and fauna habitats Major destruction of area of land, rare flora and
(< 1 month) to flora of remediated without long
ecosystem. fauna and/ or ground water
fauna habitats. term loss, localized
resources.
persistent damage; or
significant temporary
damage (< 1 year) to
ecosystem.
1

13 Source: Ministry of Housing Spatial Planning and the Environment, Netherlands; Soil Remediation Circular 2009, Annex A.
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Impact and Score10
Environmental
S. Insignificant Major Catastrophic
Component Minor Consequence Moderate Consequence
No. Consequence Consequence Consequence
Impacted
(+/-) 2 points (+/-) 3 points
(+/-) 1 point (+/-) 4 points (+/-) 5 points
C1 C2 C3 C4 C5 C6 C7
Damage to an extensive
Significant localized impacts
Minor impact on aquatic portion of aquatic
but without long term Significant widespread
Ecology and Occasional short term ecosystem, including flora, ecosystem resulting in
impact on aquatic impact on protected wildlife
7.2 Bio-diversity: impact and / or disruption fauna and habitat. No severe impacts on aquatic
ecosystem and/or short or aquatic ecosystem of
Aquatic to aquatic flora and fauna significant impact on water population and habitats and
term impacts on water moderate duration
resources. or long term impact on
resources.
water resources.
Possible Temporary or Permanent Migration, Persons as a % of Population of Study Area
Socio-economic
<0.5% <1% <1.5% <2% 2.5%
Environment:
Possible Change in Ethnicity, vis-à-vis Major Existing Ethnicities Present in Study Area
Social Aspects -
give the mean Not Likely Possible Limited Significant Severe
8.1
score from the Gender Imbalance, as a Proportion to Existing Sex-Ratio
categories,
Not Likely Possible Limited Significant Severe
rounded to the
Possibility of Return to Original Status in Terms of Any or All of the Above Changes
nearest decimal
<1 year <2 years <3 years <5 years Permanent Change
Socio-economic No of Jobs Gained or Lost
Environment: <50 Up to 75 Up to 100 Up to 250 Up to 500 or more
Economic Persons Having Loss or Gain in Income
Aspects - give
<50 100 250 500 1000 or more
8.2 the mean score
Land Losers
from the
categories, <10 <20 <50 <100 >100
rounded to the Losers of Homesteads
nearest decimal <5 <10 <25 <50 >50
Socio-economic Minor repairable damage to Moderate damage to Major damage to structures Irreparable damage to
Minor repairable damage to
8.3 Aspects: structures / items of structures/ items of cultural / items of cultural highly valued structures /
commonplace structures
Cultural cultural significance, or significance, or significant, significance, or major items / locations of cultural
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Impact and Score10
Environmental
S. Insignificant Major Catastrophic
Component Minor Consequence Moderate Consequence
No. Consequence Consequence Consequence
Impacted
(+/-) 2 points (+/-) 3 points
(+/-) 1 point (+/-) 4 points (+/-) 5 points
C1 C2 C3 C4 C5 C6 C7
minor infringements of infringement of cultural infringement of cultural significance or sacred value
cultural values values/ sacred location values / sacred locations
Occupational /
Community Minor complaints or Ongoing complaints from
Major ongoing long term
Health and exposure to community. community. Significant Extreme health risk-
Insignificant impact on health effects likely to
9.1 Safety: Maximum occurrence emission or discharge that potential for death in
surrounding communities surrounding communities
Community limited to two times per impacts on surrounding community
and workers
Health and year population
Safety
Occupational /
Near miss incident or trivial Serious injuries requiring off
Community Injuries requiring onsite
injuries, this may require site treatment by medical
Health and treatment by medical
self administered first aid. practitioner or immediate
9.2 Safety: practitioner. Personnel Single Fatality Multiple Fatality
Injured personnel can evacuation to hospital.
Occupational unable to continue to
continue to perform normal Potential long term or
Health and perform duties
duties permanent disabling effect
Safety

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2. Quantifying the Probability of Occurrence of the Impact
After identifying the consequence severity as shown in Table 5-1, the probability of occurrence also
needs to be estimated to arrive at a complete picture of environmental impact risk. Table 5-2
provides probability / likelihood ratings on a scale of 1-5. These ratings are used for estimating the
likelihood of each occurrence.
Table 5-2: Probability of Occurrence
Description Environment/Health and Safety Probability
Continues or will happen every time during the exploratory drilling
Frequent 5
program
Often Occur several times during the exploratory drilling program 4
Likely Might occur at least once during the exploratory drilling 3
Possible Might occur during the exploratory drilling 2
Rare Very rarely encountered in during the exploratory drilling 1
3. Quantifying Environmental Impact Risk
The level of environmental impact risk is calculated by multiplying the consequence score and the
probability of occurrence together. Thus
Significance of Impact = Consequence Score × Probability of Occurrence
The final score is in relative point score, rather than actual impact. The impact estimation is carried
out assuming a well managed exploratory program with the use of standard safety measures. Table
5-3 below assigns significance criteria, based on the scale of 1-25, used for prioritizing mitigation
measures for reducing the environmental impact risks and thereafter, formulating and implementing
Environmental Management Plans (EMPs).
To do this, environmental impact risk levels are first scored and identified as mentioned earlier and
then evaluated on the evaluation scale that follows in Table 5-3.
Table 5-3: Environmental Impact Significance Criteria
Consequence
Probability Insignificant Minor Moderate Major Catastrophic
(1) (2) (3) (4) (5)
Rare (1) 1 2 3 4 5
Possible (2) 2 4 6 8 10
Likely (3) 3 6 9 12 15
Often (4) 4 8 12 16 20
Certain (5) 5 10 15 20 25
4. Identifying Activities Causing Unacceptable Levels of Environmental Risk
Environmental risks are now clubbed into four levels from extreme risk to low risk activities. Extreme
risk activities are unacceptable and therefore need to be either stopped or modified such that they are
brought to a lower level of environmental risk.
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High and moderate risk activities, although acceptable, require being evaluated and mitigated in a
manner that their consequences / probabilities are lowered, with more focus on high risk activities vis-
à-vis moderate risk activities. Low risk activities do not require further mitigation. This is summarized
in Table 5-4.
Table 5-4: Environmental Risk Categorization
Score Type of Risk Action Required
15-25 Extreme Risk Activity should not proceed in current form
Activity should be modified to include remedial planning and actions and be subject
8-12 High Risk
to detailed EHS assessment
Moderate
4-6 Activity can operate subject to management and / or modification
Risk
1-3 Low Risk No action required unless escalation of risk is possible
Mitigation Measures
Mitigation measures require being formulated and implemented for all high risk and moderate risk
activities. A programme to implement all mitigation measures is then prepared and presented as an
Environmental Management Programme, presented in Chapter 9.
Impact Assessment for the Exploratory Drilling Programme of ONGC, based on the methodology
described here, is given in the next section.
5.3 Identification of Impacting Activities for the Proposed Project
As discussed earlier, environmental impacts have been identified based on an assessment of
environmental aspects associated with the project. The symbol ‘●’ indicates an adverse impact and ‘o’ 
indicates a beneficial impact.
Identified environmental impacts have been listed in Table 5-5.
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Table 5-5: Aspect – Impact Identification
Potential Environmental Impacts on Environment
over Q) n (NV) SW) GW) ersity (SE) alth, th & &S)
NSo. . Project Activities / Aspects Landuse/ Landc (LU/LC) Air Quality (A Noise and Vibratio Surface Water ( Ground Water ( Soil (S) Ecology & Bio-div (EB) Socio-Economic Occupational He Community Heal Safety (OH / CH Remarks
C1 C12
C1 C2 C3 C4 C7 C5 C9 C6 C8 C11
0
1 Site Selection
LU: Potential change in landuse / land cover; SE:
1.1 Land lease or purchase ● o
compensation to land owner against lease
2 Preparation of Site  
LC: Change in land cover; AQ / NV: air emissions,
noise and vibration from vehicles and road laying
Clearance of vegetation at site and
2.1 ● ● ● ● ● o ● equipment; S: soil erosion; EB: loss of green
preparation of approach roads
cover; SE: improved local roads; OH: risk of
occupational injuries
AQ / NV: air and noise emissions; SE: hiring of
Vehicle movement for transportation of vehicles and transport equipment / potential
2.2 ● ● o ● ●
rig, materials and equipment damage to village roads; OH/ CH&S: risk of
spillage of hazardous materials
LC: Change in land cover due to excavation;
AQ/NV: air emission and noise due excavation
operations; S: removal of topsoil; SE: Temporary
2.3 Excavation and paving of site ● ● ● ● o ●
job creation for excavation and site preparation
work; OH: Occupational risk due to excavation
work
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